Spray-deposition and photopolymerization of organic-inorganic thiol-ene resins for fabrication of superamphiphobic surfaces.

PubMed

Xiong, Li; Kendrick, Laken L; Heusser, Hannele; Webb, Jamie C; Sparks, Bradley J; Goetz, James T; Guo, Wei; Stafford, Christopher M; Blanton, Michael D; Nazarenko, Sergei; Patton, Derek L

2014-07-09

Superamphiphobic surfaces, exhibiting high contact angles and low contact angle hysteresis to both water and low surface tension liquids, have attracted a great deal attention in recent years because of the potential of these materials in practical applications such as liquid-resistant textiles, self-cleaning surfaces, and antifouling/anticorrosion coatings. In this work, we present a simple strategy for fabricating of superamphiphobic coatings based on photopolymerization of hybrid thiol-ene resins. Spray-deposition and UV photopolymerization of thiol-ene resins containing hydrophobic silica nanoparticles and perfluorinated thiols provide a multiscale topography and low-energy surface that endows the surface with superamphiphobicity. The wettability and chemical composition of the surfaces were characterized by contact-angle goniometry and X-ray photoelectron spectroscopy, respectively. The hierarchical roughness features of the thiol-ene surfaces were investigated with field-emission scanning electron microscopy. Droplet impact and sandpaper abrasion tests indicate the coatings respectively possess a robust antiwetting behavior and good mechanical durability.

Synthesis of Single-walled Carbon Nanotubes Coated with Thiol-reactive Gel via Emulsion Polymerization.

PubMed

Nagai, Yukiko; Tsutsumi, Yusuke; Nakashima, Naotoshi; Fujigaya, Tsuyohiko

2018-06-15

Single-walled carbon nanotubes (SWNTs) have unique near-infrared absorption and photoemission properties that are attractive for in vivo biological applications such as photothermal cancer treatment and bioimaging. Therefore, a smart functionalization strategy for SWNTs to create biocompatible surfaces and introduce various ligands to target active cancer cells without losing the unique optical properties of the SWNTs is strongly desired. This paper reports the de-sign and synthesis of a SWNT/gel hybrid containing maleimide groups, which react with various thiol compounds through Michael addition reactions. In this hybrid, the method called carbon nanotube micelle polymerization was used to non-covalently modify the surface of SWNTs with a cross-linked polymer gel layer. This method can form an extremely stable gel layer on SWNTs; such stability is essential for in vivo biological applications. The monomer used to form the gel layer contained a maleimide group, which was protected with furan in endo-form. The resulting hybrid was treated in water to induce deprotection via retro Diels-Alder reaction and then functionalized with thiol com-pounds through Michael addition. The functionalization of the hybrid was explored using a thiol-containing fluores-cent dye as a model thiol and the formation of the SWNT-dye conjugate was confirmed by energy transfer from the dye to SWNTs. Our strategy offers a promising SWNT-based platform for biological functionalization for cancer targeting, imaging, and treatment.

Designing a Binding Interface for Control of Cancer Cell Adhesion via 3D Topography and Metabolic Oligosaccharide Engineering

PubMed Central

Du, Jian; Che, Pao-Lin; Wang, Zhi-Yun; Aich, Udayanath; Yarema, Kevin J.

2011-01-01

This study combines metabolic oligosaccharide engineering (MOE), a technology where the glycocalyx of living cells is endowed with chemical features not normally found in sugars, with custom-designed three dimensional biomaterial substrates to enhance the adhesion of cancer cells and control their morphology and gene expression. Specifically, Ac5ManNTGc, a thiol-bearing analogue of N-acetyl-d-mannosamine (ManNAc) was used to introduce thiolated sialic acids into the glycocalyx of human Jurkat T-lymphoma derived cells. In parallel 2D films and 3D electrospun nanofibrous scaffolds were prepared from polyethersulfone (PES) and (as controls) left unmodified or aminated. Alternately, the materials were malemided or gold-coated to provide bioorthogonal binding partners for the thiol groups newly expressed on the cell surface. Cell attachment was modulated by both the topography of the substrate surface and by the chemical compatibility of the binding interface between the cell and the substrate; a substantial increase in binding for normally non-adhesive Jurkat line for 3D scaffold compared to 2D surfaces with an added degree of adhesion resulting from chemoselective binding to malemidede-derivatived or gold-coated surfaces. In addition, the morphology of the cells attached to the 3D scaffolds via MOE-mediated adhesion was dramatically altered and the expression of genes involved in cell adhesion changed in a time-dependent manner. This study showed that cell adhesion could be enhanced, gene expression modulated, and cell fate controlled by introducing the 3D topograhical cues into the growth substrate and by creating a glycoengineered binding interface where the chemistry of both the cell surface and biomaterials scaffold was controlled to facilitate a new mode of carbohydrate-mediated adhesion. PMID:21549424

Proteomic detection of oxidized and reduced thiol proteins in cultured cells.

PubMed

Cuddihy, Sarah L; Baty, James W; Brown, Kristin K; Winterbourn, Christine C; Hampton, Mark B

2009-01-01

The oxidation and reduction of cysteine residues is emerging as an important post-translational control of protein function. We describe a method for fluorescent labelling of either reduced or oxidized thiols in combination with two-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (2DE) to detect changes in the redox proteome of cultured cells. Reduced thiols are labelled with the fluorescent compound 5-iodoacetamidofluorescein. To monitor oxidized thiols, the reduced thiols are first blocked with N-ethyl-maleimide, then the oxidized thiols reduced with dithiothreitol and labelled with 5-iodoacetamidofluorescein. The method is illustrated by treating Jurkat T-lymphoma cells with hydrogen peroxide and monitoring increased labelling of oxidized thiol proteins. A decrease in labelling can also be detected, and this is attributed to the formation of higher oxidation states of cysteine that are not reduced by dithiothreitol.

Photogenerated Lectin Sensors Produced by Thiol-Ene/Yne Photo-Click Chemistry in Aqueous Solution

PubMed Central

Norberg, Oscar; Lee, Irene H.; Aastrup, Teodor; Yan, Mingdi; Ramström, Olof

2012-01-01

The photoinitiated radical reactions between thiols and alkenes/alkynes (thiol-ene and thiol-yne chemistry) have been applied to a functionalization methodology to produce carbohydrate-presenting surfaces for analyses of biomolecular interactions. Polymer-coated quartz surfaces were functionalized with alkenes or alkynes in a straightforward photochemical procedure utilizing perfluorophenylazide (PFPA) chemistry. The alkene/alkyne surfaces were subsequently allowed to react with carbohydrate thiols in water under UV-irradiation. The reaction can be carried out in a drop of water directly on the surface without photoinitiator and any disulfide side products were easily washed away after the functionalization process. The resulting carbohydrate-presenting surfaces were evaluated in real-time studies of protein-carbohydrate interactions using a quartz crystal microbalance flow-through system with recurring injections of selected lectins with intermediate regeneration steps using low pH buffer. The resulting methodology proved fast, efficient and scalable to high-throughput analysis formats, and the produced surfaces showed significant protein binding with expected selectivities of the lectins used in the study. PMID:22341757

Mercury reduction and cell-surface adsorption by Geobacter sulfurreducens PCA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Haiyan; Lin, Hui; Zheng, Wang

2013-01-01

Both reduction and surface adsorption of mercuric mercury [Hg(II)] are found to occur simultaneously on G. sulfurreducens PCA cells under dark, anaerobic conditions. Reduction of Hg(II) to elemental Hg(0) initially follows a pseudo-first order kinetics with a half-life of < 2 h in the presence of 50 nM Hg(II) and 1011 cells L-1 in a phosphate buffer (pH 7.4). Multiple gene deletions of the outer membrane cytochromes in this organism resulted in decrease in reduction rate from ~ 0.3 to 0.05 h-1, and reduction was nearly absent with heat-killed cells or in the cell filtrate. Adsorption of Hg(II) by cellsmore » is found to compete with, and thus inhibit, Hg(II) reduction. Depending on the Hg to cell ratio, maximum Hg(II) reduction was observed at about 5 10-19 mol Hg cell-1, but reduction terminated at a low Hg to cell ratio (< 10-20 mol Hg cell-1). This inhibitory effect is attributed to strong binding between Hg(II) and the thiol ( SH) functional groups on cells and validated by experiments in which the sorbed Hg(II) was readily exchanged by thiols (e.g., glutathione) but not by carboxylic ligands such as ethylenediaminetetraacetate (EDTA). We suggest that coupled Hg(II)-cell interactions, i.e., reduction and surface binding, could be important in controlling Hg species transformation and bioavailability and should therefore be considered in microbial Hg(II) uptake and methylation studies.« less

Mitochondrial thiol modification by a targeted electrophile inhibits metabolism in breast adenocarcinoma cells by inhibiting enzyme activity and protein levels.

PubMed

Smith, M Ryan; Vayalil, Praveen K; Zhou, Fen; Benavides, Gloria A; Beggs, Reena R; Golzarian, Hafez; Nijampatnam, Bhavitavya; Oliver, Patsy G; Smith, Robin A J; Murphy, Michael P; Velu, Sadanandan E; Landar, Aimee

2016-08-01

Many cancer cells follow an aberrant metabolic program to maintain energy for rapid cell proliferation. Metabolic reprogramming often involves the upregulation of glutaminolysis to generate reducing equivalents for the electron transport chain and amino acids for protein synthesis. Critical enzymes involved in metabolism possess a reactive thiolate group, which can be modified by certain oxidants. In the current study, we show that modification of mitochondrial protein thiols by a model compound, iodobutyl triphenylphosphonium (IBTP), decreased mitochondrial metabolism and ATP in MDA-MB 231 (MB231) breast adenocarcinoma cells up to 6 days after an initial 24h treatment. Mitochondrial thiol modification also depressed oxygen consumption rates (OCR) in a dose-dependent manner to a greater extent than a non-thiol modifying analog, suggesting that thiol reactivity is an important factor in the inhibition of cancer cell metabolism. In non-tumorigenic MCF-10A cells, IBTP also decreased OCR; however the extracellular acidification rate was significantly increased at all but the highest concentration (10µM) of IBTP indicating that thiol modification can have significantly different effects on bioenergetics in tumorigenic versus non-tumorigenic cells. ATP and other adenonucleotide levels were also decreased by thiol modification up to 6 days post-treatment, indicating a decreased overall energetic state in MB231 cells. Cellular proliferation of MB231 cells was also inhibited up to 6 days post-treatment with little change to cell viability. Targeted metabolomic analyses revealed that thiol modification caused depletion of both Krebs cycle and glutaminolysis intermediates. Further experiments revealed that the activity of the Krebs cycle enzyme, aconitase, was attenuated in response to thiol modification. Additionally, the inhibition of glutaminolysis corresponded to decreased glutaminase C (GAC) protein levels, although other protein levels were unaffected. This study demonstrates for the first time that mitochondrial thiol modification inhibits metabolism via inhibition of both aconitase and GAC in a breast cancer cell model. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Expedient generation of patterned surface aldehydes by microfluidic oxidation for chemoselective immobilization of ligands and cells.

PubMed

Westcott, Nathan P; Pulsipher, Abigail; Lamb, Brian M; Yousaf, Muhammad N

2008-09-02

An expedient and inexpensive method to generate patterned aldehydes on self-assembled monolayers (SAMs) of alkanethiolates on gold with control of density for subsequent chemoselective immobilization from commercially available starting materials has been developed. Utilizing microfluidic cassettes, primary alcohol oxidation of tetra(ethylene glycol) undecane thiol and 11-mercapto-1-undecanol SAMs was performed directly on the surface generating patterned aldehyde groups with pyridinium chlorochromate. The precise density of surface aldehydes generated can be controlled and characterized by electrochemistry. For biological applications, fibroblast cells were seeded on patterned surfaces presenting biospecifc cell adhesive (Arg-Glyc-Asp) RGD peptides.

Size-controlled synthesis, surface functionalization, and biological applications of thiol-organosilica particles.

PubMed

Nakamura, Michihiro; Ozaki, Shuji; Abe, Masahiro; Doi, Hiroyuki; Matsumoto, Toshio; Ishimura, Kazunori

2010-08-01

Thiol-organosilica particles of a narrow size distribution, made from 3-mercaptopropyltrimethoxysilane (MPMS), were prepared by means of a one-pot synthesis. We examined three synthetic conditions at high temperature (100 degrees C), including the Stöber synthesis and two entirely aqueous syntheses. Under all conditions, the sizes of MPMS particles were well controlled, and the average of the coefficient of variation for the size distribution was less than 20%. The incubation times required for formation of MPMS particles were shorter at high temperature than at low temperature. MPMS particles internally functionalized with fluorescent dye were also prepared by means of the same one-pot synthesis. On flow cytometry analysis these MPMS particles showed distinct peaks of scattering due to well-controlled sizes of particles as well as due to fluorescence signals. Real-time observation of interaction between fluorescent MPMPS particles and cultured cells could be observed under fluorescent microscopy with bright light. The surface of the as-prepared MPMS particles contained exposed mercaptopropyl residues, and the ability to adsorb proteins was at least 6 times higher than that of gold nanopaticles. In addition, fluorescein-labeled proteins adsorbed to the surface of the particles were quantitatively detected at the pg/ml level by flow cytometry. MPMS particles surface functionalized with anti-CD20 antibody using adsorption could bind with lymphoma cells expressing CD20 specifically. In this paper, we demonstrated the possibility of size-controlled thiol-organosilica particles for wild range of biological applications. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Detection of intracellular glutathione using ThiolTracker violet stain and fluorescence microscopy.

PubMed

Mandavilli, Bhaskar S; Janes, Michael S

2010-07-01

Glutathione plays an important role in protecting mammalian cells from oxidative stress and cell death. Because reduced glutathione (GSH) represents the large majority of intracellular free thiols, cell-permeant, thiol-reactive fluorescent probes represent potentially useful indicators of intracellular GSH. The ThiolTracker Violet stain (a registered trademark of Invitrogen) is a bright fluorescent probe that is highly reactive to thiols and can be used as a convenient and effective indicator of intracellular GSH and general redox status by a variety of detection modalities. While this probe has been validated in flow cytometry and microplate fluorimetry assays, the following method will describe details on the use of the ThiolTracker Violet dye in traditional fluorescence microscopy, as well as high-content imaging and analysis.

Thiol-reactive amphiphilic block copolymer for coating gold nanoparticles with neutral and functionable surfaces

PubMed Central

Chen, Hongwei; Zou, Hao; Paholak, Hayley J.; Ito, Masayuki; Qian, Wei; Che, Yong; Sun, Duxin

2014-01-01

Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups, such as –COOH and –NH2, to conjugate targeting ligands or drugs. However, introducing highly charged surfaces promotes binding of the nanoparticles to biomolecules in biological systems through ionic interactions, causing the nanoparticles to aggregate in biological environments and consequently undergo strong non-specific binding to off-target cells and tissues. Developing a unique polymer with neutral surfaces that can be further functionalized directly would be critical to develop suitable nanomaterials for nanomedicine. Here, we report a thiol-reactive amphiphilic block copolymer poly(ethylene oxide)-block-poly(pyridyldisulfide ethylmeth acrylate) (PEO-b-PPDSM) for coating gold nanoparticles (AuNPs). The resultant polymer-coated AuNPs have almost neutral surfaces with slightly negative zeta potentials from -10 to 0 mV over a wide pH range from 2 to 12. Although the zeta potential is close to zero we show that the PEO-b-PPDSM copolymer-coated AuNPs have both good stability in various physiological conditions and reduced non-specific adsorption of proteins/biomolecules. Because of the multiple pyridyldisulfide groups on the PPDSM block, these individually dispersed nanocomplexes with an overall hydrodynamic size around 43.8 nm can be directly functionalized via disulfide-thiol exchange chemistry. PMID:24729795

Thiols decrease cytokine levels and down-regulate the expression of CD30 on human allergen-specific T helper (Th) 0 and Th2 cells

PubMed Central

Bengtsson, Å; Lundberg, M; Avila-Cariño, J; Jacobsson, G; Holmgren, A; Scheynius, A

2001-01-01

The thiol antioxidant N-acetyl-l-cysteine (NAC), known as a precursor of glutathione (GSH), is used in AIDS treatment trials, as a chemoprotectant in cancer chemotherapy and in treatment of chronic bronchitis. In vitro, GSH and NAC are known to enhance T cell proliferation, production of IL-2 and up-regulation of the IL-2 receptor. The 120-kD CD30 surface antigen belongs to the tumour necrosis factor (TNF) receptor superfamily. It is expressed by activated T helper (Th) cells and its expression is sustained in Th2 cells. We have analysed the effect of GSH and NAC on the cytokine profile and CD30 expression on human allergen-specific T cell clones (TCC). TCC were stimulated with anti-CD3 antibodies in the presence of different concentrations of GSH and NAC. Both thiols caused a dose dependent down-regulation of IL-4, IL-5 and IFN-γ levels in Th0 and Th2 clones, with the most pronounced decrease of IL-4. Furthermore, they down-regulated the surface expression of CD30, and the levels of soluble CD30 (sCD30) in the culture supernatants were decreased. In contrast, the surface expression of CD28 or CD40 ligand (CD40L) was not significantly changed after treatment with 20 mm NAC. These results indicate that GSH and NAC favour a Th1 response by a preferential down-regulation of IL-4. In addition, the expression of CD30 was down regulated by GSH and NAC, suggesting that CD30 expression is dependent on IL-4, or modified by NAC. In the likely event that CD30 and its soluble counterpart prove to contribute to the pathogenesis in Th2 related diseases such as allergy, NAC may be considered as a future therapeutic agent in the treatment of these diseases. PMID:11298119

Surface thiolation of silicon for antifouling application.

PubMed

Zhang, Xiaoning; Gao, Pei; Hollimon, Valerie; Brodus, DaShan; Johnson, Arion; Hu, Hongmei

2018-02-07

Thiol groups grafted silicon surface was prepared as previously described. 1H,1H,2H,2H-perfluorodecanethiol (PFDT) molecules were then immobilized on such a surface through disulfide bonds formation. To investigate the contribution of PFDT coating to antifouling, the adhesion behaviors of Botryococcus braunii (B. braunii) and Escherichia coli (E. coli) were studied through biofouling assays in the laboratory. The representative microscope images suggest reduced B. braunii and E. coli accumulation densities on PFDT integrated silicon substrate. However, the antifouling performance of PFDT integrated silicon substrate decreased over time. By incubating the aged substrate in 10 mM TCEP·HCl solution for 1 h, the fouled PFDT coating could be removed as the disulfide bonds were cleaved, resulting in reduced absorption of algal cells and exposure of non-fouled silicon substrate surface. Our results indicate that the thiol-terminated substrate can be potentially useful for restoring the fouled surface, as well as maximizing the effective usage of the substrate.

Toposelective electrochemical desorption of thiol SAMs from neighboring polycrystalline gold surfaces.

PubMed

Tencer, Michal; Berini, Pierre

2008-11-04

We describe a method for the selective desorption of thiol self-assembled monolayers from gold surfaces having micrometer-scale separations on a substrate. In an electrolyte solution, the electrical resistance between the adjacent areas can be much lower than the resistance between a surface and the counter electrode. Also, both reductive and oxidative thiol desorption may occur. Therefore, the potentials of the surfaces must be independently controlled with a multichannel potentiostat and operating windows for a given thiol/electrolyte system must be established. In this study operating windows were established for 1-dodecanethiol-based SAMs in phosphate buffer, phosphate-buffered saline, and sodium hydroxide solution, and selective SAM removal was successfully performed in a four-electrode configuration.

Simulation studies on structural and thermal properties of alkane thiol capped gold nanoparticles.

PubMed

Devi, J Meena

2017-06-01

The structural and thermal properties of the passivated gold nanoparticles were explored employing molecular dynamics simulation for the different surface coverage densities of the self-assembled monolayer (SAM) of alkane thiol. The structural properties of the monolayer protected gold nanoparticles such us overall shape, organization and conformation of the capping alkane thiol chains were found to be influenced by the capping density. The structural order of the thiol capped gold nanoparticles enhances with the increase in the surface coverage density. The specific heat capacity of the alkane thiol capped gold nanoparticles was found to increase linearly with the thiol coverage density. This may be attributed to the enhancement in the lattice vibrational energy. The present simulation results suggest, that the structural and thermal properties of the alkane thiol capped gold nanoparticles may be modified by the suitable selection of the SAM coverage density. Copyright © 2017 Elsevier Inc. All rights reserved.

Protein disulfide isomerase and Nox: new partners in redox signaling.

PubMed

Trevelin, Silvia Cellone; Lopes, Lucia Rossetti

2015-01-01

Reactive oxygen species (ROS) contribute to the pathogenesis of cardiovascular disease, including hypertension, atherosclerosis, cardiac hypertrophy, heart failure and restenosis. Thiol proteins and thiol oxidoreductases are key players in cell signaling, and their altered expression and/or activity has been associated with a disrupture in cardiac and vascular homeostasis. Protein disulfide isomerase (PDI) is a thiol oxidoreductase member of the thioredoxin family that has multiple roles in cellular function. Originally discovered in the endoplasmic reticulum (ER), PDI is essential for protein folding. However, it can also be found in the cytosol and closely associated with the surface of platelets, smooth muscle cells, neutrophils and endothelial cells. On the cell surface, PDI is imperative for platelet aggregation and transnitrosation, which are related to thrombosis and control of vascular tone by nitric oxide, respectively. Furthermore, PDI signaling contributes to redox-dependent events such as smooth muscle cell migration induced by PDGF and TNFα-dependent angiogenesis. Studies from our group have shown that intracellular PDI regulates the expression and activity of the NADPH oxidase family of proteins (Nox), which are enzymes dedicated to ROS generation. PDI acts as a new organizer of leukocyte Nox2 by redox dependently associating with p47phox and controlling its recruitment to the plasma membrane, an essential step for assembly of the active enzyme. Such multiple effects of PDI suggest that specific targeting of this oxidoreductase could represent a new approach in the treatment of vascular disease. In this review, we present a novel role for PDI as an adaptor protein involved in redox processes and Nox signaling and propose PDI as a potential therapeutic target in the treatment of atherosclerosis, thrombosis and hypertension.

Methods of measuring Protein Disulfide Isomerase activity: a critical overview

NASA Astrophysics Data System (ADS)

Watanabe, Monica; Laurindo, Francisco; Fernandes, Denise

2014-09-01

Protein disulfide isomerase is an essential redox chaperone from the endoplasmic reticulum (ER) and is responsible for correct disulfide bond formation in nascent proteins. PDI is also found in other cellular locations in the cell, particularly the cell surface. Overall, PDI contributes to ER and global cell redox homeostasis and signaling. The knowledge about PDI structure and function progressed substantially based on in vitro studies using recombinant PDI and chimeric proteins. In these experimental scenarios, PDI reductase and chaperone activities are readily approachable. In contrast, assays to measure PDI isomerase activity, the hallmark of PDI family, are more complex. Assessment of PDI roles in cells and tissues mainly relies on gain- or loss-of-function studies. However, there is limited information regarding correlation of experimental readouts with the distinct types of PDI activities. In this mini-review, we evaluate the main methods described for measuring the different kinds of PDI activity: thiol reductase, thiol oxidase, thiol isomerase and chaperone. We emphasize the need to use appropriate controls and the role of critical interferents (e.g., detergent, presence of reducing agents). We also discuss the translation of results from in vitro studies with purified recombinant PDI to cellular and tissue samples, with critical comments on the interpretation of results.

Diamond surface functionalization with biomimicry - Amine surface tether and thiol moiety for electrochemical sensors

NASA Astrophysics Data System (ADS)

Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.

2014-05-01

The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen-oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

Surface modification of model hydrogel contact lenses with hyaluronic acid via thiol-ene "click" chemistry for enhancing surface characteristics.

PubMed

Korogiannaki, Myrto; Zhang, Jianfeng; Sheardown, Heather

2017-10-01

Discontinuation of contact lens wear as a result of ocular dryness and discomfort is extremely common; as many as 26% of contact lens wearers discontinue use within the first year. While patients are generally satisfied with conventional hydrogel lenses, improving on-eye comfort continues to remain a goal. Surface modification with a biomimetic, ocular friendly hydrophilic layer of a wetting agent is hypothesized to improve the interfacial interactions of the contact lens with the ocular surface. In this work, the synthesis and characterization of poly(2-hydroxyethyl methacrylate) surfaces grafted with a hydrophilic layer of hyaluronic acid are described. The immobilization reaction involved the covalent attachment of thiolated hyaluronic acid (20 kDa) on acrylated poly(2-hydroxyethyl methacrylate) via nucleophile-initiated Michael addition thiol-ene "click" chemistry. The surface chemistry of the modified surfaces was analyzed by Fourier transform infrared spectroscopy-attenuated total reflectance and X-ray photoelectron spectroscopy. The appearance of N (1s) and S (2p) peaks on the low resolution X-ray photoelectron spectroscopy spectra confirmed successful immobilization of hyaluronic acid. Grafting hyaluronic acid to the poly(2-hydroxyethyl methacrylate) surfaces decreased the contact angle, the dehydration rate, and the amount of nonspecific sorption of lysozyme and albumin in comparison to pristine hydrogel materials, suggesting the development of more wettable surfaces with improved water-retentive and antifouling properties, while maintaining optical transparency (>92%). In vitro testing also showed excellent viability of human corneal epithelial cells with the hyaluronic acid-grafted poly(2-hydroxyethyl methacrylate) surfaces. Hence, surface modification with hyaluronic acid via thiol-ene "click" chemistry could be useful in improving contact lens surface properties, potentially alleviating symptoms of contact lens related dryness and discomfort during wear.

Thiol-redox signaling, dopaminergic cell death, and Parkinson's disease.

PubMed

Garcia-Garcia, Aracely; Zavala-Flores, Laura; Rodriguez-Rocha, Humberto; Franco, Rodrigo

2012-12-15

Parkinson's disease (PD) is characterized by the selective loss of dopaminergic neurons of the substantia nigra pars compacta, which has been widely associated with oxidative stress. However, the mechanisms by which redox signaling regulates cell death progression remain elusive. Early studies demonstrated that depletion of glutathione (GSH), the most abundant low-molecular-weight thiol and major antioxidant defense in cells, is one of the earliest biochemical events associated with PD, prompting researchers to determine the role of oxidative stress in dopaminergic cell death. Since then, the concept of oxidative stress has evolved into redox signaling, and its complexity is highlighted by the discovery of a variety of thiol-based redox-dependent processes regulating not only oxidative damage, but also the activation of a myriad of signaling/enzymatic mechanisms. GSH and GSH-based antioxidant systems are important regulators of neurodegeneration associated with PD. In addition, thiol-based redox systems, such as peroxiredoxins, thioredoxins, metallothioneins, methionine sulfoxide reductases, transcription factors, as well as oxidative modifications in protein thiols (cysteines), including cysteine hydroxylation, glutathionylation, and nitrosylation, have been demonstrated to regulate dopaminergic cell loss. In this review, we summarize major advances in the understanding of the role of thiol-redox signaling in dopaminergic cell death in experimental PD. Future research is still required to clearly understand how integrated thiol-redox signaling regulates the activation of the cell death machinery, and the knowledge generated should open new avenues for the design of novel therapeutic approaches against PD.

Mechanistic investigation of Fe(III) oxide reduction by low molecular weight organic sulfur species

NASA Astrophysics Data System (ADS)

Eitel, Eryn M.; Taillefert, Martial

2017-10-01

Low molecular weight organic sulfur species, often referred to as thiols, are known to be ubiquitous in aquatic environments and represent important chemical reductants of Fe(III) oxides. Thiols are excellent electron shuttles used during dissimilatory iron reduction, and in this capacity could indirectly affect the redox state of sediments, release adsorbed contaminants via reductive dissolution, and influence the carbon cycle through alteration of bacterial respiration processes. Interestingly, the reduction of Fe(III) oxides by thiols has not been previously investigated in environmentally relevant conditions, likely due to analytical limitations associated with the detection of thiols and their oxidized products. In this study, a novel electrochemical method was developed to simultaneously determine thiol/disulfide pair concentrations in situ during the reduction of ferrihydrite in batch reactors. First order rate laws with respect to initial thiol concentration were confirmed for Fe(III) oxyhydroxide reduction by four common thiols: cysteine, homocysteine, cysteamine, and glutathione. Zero order was determined for both Fe(III) oxyhydroxide and proton concentration at circumneutral pH. A kinetic model detailing the molecular mechanism of the reaction was optimized with proposed intermediate surface structures. Although metal oxide overall reduction rate constants were inversely proportional to the complexity of the thiol structure, the extent of metal reduction increased with structure complexity, indicating that surface complexes play a significant role in the ability of these thiols to reduce iron. Taken together, these results demonstrate the importance of considering the molecular reaction mechanism at the iron oxide surface when investigating the potential for thiols to act as electron shuttles during dissimilatory iron reduction in natural environments.

Bisphosphonate-coated BSA nanoparticles lack bone targeting after systemic administration.

PubMed

Wang, Guilin; Kucharski, Cezary; Lin, Xiaoyue; Uludağ, Hasan

2010-09-01

A polymeric conjugate of polyethyleneimine-graft-poly(ethylene glycol) and 2-(3-mercaptopropylsulfanyl)-ethyl-1,1-bisphosphonic acid (PEI-PEG-thiolBP) was prepared and used for surface coating of bovine serum albumin (BSA) nanoparticles (NPs) designed for bone-specific delivery of bone morphogenetic protein-2 (BMP-2). The NP coating was achieved with a dialysis and an evaporation method, and the obtained NPs were characterized by particle size, zeta-potential, morphology, and cytotoxicity in vitro. The particle size and surface charge of the NPs could be effectively tuned by the PEG and thiolBP substitution ratios of the conjugate, the coating method, and the polymer concentration used for coating. The PEG modification on PEI reduced the toxicity of PEI and the coated NPs, based on in vitro assessment with human C2C12 cells and rat bone marrow stromal cells. On the basis of an alkaline phosphatase (ALP) induction assay, the NP-encapsulated BMP-2 displayed full retention of its bioactivity, except for BMP-2 in PEI-coated NPs. By encapsulating (125)I-labeled BMP-2, the polymer-coated NPs were assessed for hydroxyapatite (HA) affinity; all NP-encapsulated BMP-2 showed significant affinity to HA as compared with free BMP-2 in vitro, and the PEI-PEG-thiolBP coated NPs improved the in vivo retention of BMP-2 compared with uncoated NPs. However, the biodistribution of NPs after intravenous injection in a rat model indicated no beneficial effects of thiolBP-coated NPs for bone targeting. Our results suggested that the BP-conjugated NPs are useful for localized delivery of BMP-2 in bone repair and regeneration, but they are not effective for bone targeting after intravenous administration.

Gold nanorods coupled with upconverting nanophosphors for targeted thermal ablation and imaging of bladder cancer cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cho, Suehyun K.; Su, Lih-Jen; Flaig, Thomas W.; Park, Wounjhang

2016-09-01

NaYF4:Yb3+,Er3+ upconverting nanophosphors (UCNPs) are robust and stable nanoparticles that absorb near-infrared (NIR) photons and emit green and red visible photons through energy transfer upconversion. This mechanism provides UCNPs several advantages as a bioimaging agent over traditional fluorescence imaging agent in that NIR excitation allows high-contrast imaging without autofluorescence and that they can be used for deep-tissue imaging. However, additional surface modification of UCNPs is necessary for them to be biocompatible. We use an amphiphilic polymer (poly(maleic anhydride-alt-octadecene) (PMAO) and a hetero-functional polyethylene glycol with amine and thiol ends (NH2-PEG-SH)) to make the UCNPs water-soluble. This reaction yields a carboxylic group that allows functionalization with anti-epidermal growth factor receptor (aEGFR), which provides specific binding of UCNPs to EGFR-expressing bladder cancer cells. Additionally, the thiol ends of the PEGylated UCNPs are able to bind with gold nanorods (AuNRs) to create UCNP-AuNR complexes. The localized surface plasmon of the AuNR then allow localized heating of HTB9 bladder cancer cells, enabling in situ cell killing upon detection by UCNP fluorescence. Here, we report a successful synthesis, surface modification and conjugation of aEGFR functionalized UCNP-AuNR complexes and in vitro imaging and thermal ablation studies using them. Synthesis and surface modification of UCNP-AuNR complexes are confirmed by electron microscopy. Then, a combination of brightfield, NIR confocal fluorescence, and darkfield microscopy on the UCNP-AuNR treated bladder cancer cells revealed successful cancer targeting and imaging capabilities of the complex. Finally, cell viability assay showed that NIR irradiation of UCNP-AuNR conjugated cells resulted highly selective cell killing.

Protein covalent immobilization via its scarce thiol versus abundant amine groups: Effect on orientation, cell binding domain exposure and conformational lability.

PubMed

Ba, O M; Hindie, M; Marmey, P; Gallet, O; Anselme, K; Ponche, A; Duncan, A C

2015-10-01

Quantity, orientation, conformation and covalent linkage of naturally cell adhesive proteins adsorbed or covalently linked to a surface, are known to influence the preservation of their subsequent long term cell adhesion properties and bioactivity. In the present work, we explore two different strategies for the covalent linking of plasma fibronectin (pFN) - used as a cell adhesive model protein, onto a polystyrene (PS) surface. One is aimed at tethering the protein to the surface in a semi-oriented fashion (via one of the 4 free thiol reactive groups on the protein) with a heterofunctional coupling agent (SSMPB method). The other aims to immobilize the protein in a more random fashion by reaction between the abundant pendant primary amine bearing amino acids of the pFN and activated carboxylic surface functions obtained after glutaric anhydride surface treatment (GA method). The overall goal will be to verify the hypothesis of a correlation between covalent immobilization of a model cell adhesive protein to a PS surface in a semi-oriented configuration (versus randomly oriented) with promotion of enhanced exposure of the protein's cell binding domain. This in turn would lead to enhanced cell adhesion. Ideally the goal is to elaborate substrates exhibiting a long term stable protein monolayer with preserved cell adhesive properties and bioactivity for biomaterial and/or cell adhesion commercial plate applications. However, the initial restrictive objective of this paper is to first quantitatively and qualitatively investigate the reversibly (merely adsorbed) versus covalently irreversibly bound protein to the surface after the immobilization procedure. Although immobilized surface amounts were similar (close to the monolayer range) for all immobilization approaches, covalent grafting showed improved retention and stronger "tethering" of the pFN protein to the surface (roughly 40%) after SDS rinsing compared to that for mere adsorption (0%) suggesting an added value to the covalent grafting immobilization methods. However no differences in exposure of the cell binding domains were observed (ELISA results) before SDS rinsing, suggesting that pFN protein grafting to the surface is initially kinetically driven be a stochastic random adsorption phenomenon. Covalent grafting acts in the final stage as a process that simply tethers and stabilizes (or freezes) the initial conformation/orientation of the adsorbed protein on the surface. In addition covalent linkage via the SSMPB approach is likely favored by surface-induce exposure of one of the normally hidden free thiol group pair, thus optimizing covalent linkage to the surface. However after SDS rinsing, this "tethering"/"freezing" effect was significantly more prominent for the GA grafting approach (due to greater number of potential covalent links between the protein and the surface) compared to that for the SSMPB approach. This hypothesis was buttressed by the improved resistance to denaturation (smaller conformational lability) for the GA compared to the SMPB approach and improved exposure of the cell binding domain for the former (>50%) even after SDS rinsing. These results are promising in that they suggest covalent tethering of fibronectin to PS substrate in a monolayer range, with significantly improved irreversible protein surface bonding via both approaches (compared to that for mere adsorption). The latter are likely applicable to a wide range of proteins. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrangea-like magneto-fluorescent nanoparticles through thiol-inducing assembly

NASA Astrophysics Data System (ADS)

Chen, Shun; Zhang, Junjun; Song, Shaokun; Xiong, Chuanxi; Dong, Lijie

2017-01-01

Magneto-fluorescent nanoparticles (NPs), recognized as an emerging class of materials, have drawn much attention because of their potential applications. Due to surface functionalization and thiol-metal bonds, a simple method has been put forward for fabricating hydrangea-like magneto-fluorescent Fe3O4-SH@QD NPs, through assembling thiol-modified Fe3O4 NPs with sub-size multi-layer core/shell CdSe/CdS/ZnS QDs. After a refined but controllable silane hydrolysis process, thiol-modified Fe3O4 was fabricated, resulting in Fe3O4-SH@QD NPs with QDs, while preventing the quenching of the QDs. As a result, the core Fe3O4 NPs were 18 nm in diameter, while the scattered CdSe/CdS/ZnS QDs were 7 nm in diameter. The resultant magneto-fluorescent Fe3O4-SH@QD NPs exhibit efficient fluorescence, superparamagnetism at room temperature, and rapid response to the external field, which make them ideal candidates for difunctional probes in MRI and bio-labels, targeting and photodynamic therapy, and cell tracking and separation.

Micelle Delivery of Parthenolide to Acute Myeloid Leukemia Cells

PubMed Central

Baranello, Michael P.; Bauer, Louisa; Jordan, Craig T.; Benoit, Danielle S. W.

2018-01-01

Parthenolide (PTL) has shown great promise as a novel anti-leukemia agent as it selectively eliminates acute myeloid leukemia (AML) blast cells and leukemia stem cells (LSCs) while sparing normal hematopoietic cells. This success has not yet translated to the clinical setting because PTL is rapidly cleared from blood due to its hydrophobicity. To increase the aqueous solubility of PTL, we previously developed micelles formed from predominantly hydrophobic amphiphilic diblock copolymers of poly(styrene-alt-maleic anhydride)-b-poly(styrene) (e.g., PSMA100-b-PS258) that exhibit robust PTL loading (75%efficiency, 11% w/w capacity) and release PTL over 24 h. Here, PTL-loaded PSMA-b-PS micelles were thoroughly characterized in vitro for PTL delivery to MV4-11 AML cells. Additionally, the mechanisms governing micelle-mediated cytotoxicity were examined in comparison to free PTL. PSMA-b-PS micelles were taken up by MV4-11 cells as evidenced by transmission electron microscopy and flow cytometry. Specifically, MV4-11 cells relied on clathrin-mediated endocytosis, rather than caveolae-mediated endocytosis and macropinocytosis. In addition, PTL-loaded PSMA-b-PS micelles exhibited a dose-dependent cytotoxicity towards AML cells and were capable of reducing cell viability by 75% at 10 μM PTL, while unloaded micelles were nontoxic. At 10 μM PTL, the cytotoxicity of PTL-loaded micelles increased gradually over 24 h while free PTL achieved maximal cytotoxicity between 2 and 4 h, demonstrating micelle-mediated delivery of PTL to AML cells and stability of the drug-loaded micelle even in the presence of cells. Both free PTL and PTL-loaded micelles induced NF-κB inhibition at 10 μM PTL doses, demonstrating some mechanistic similarities in cytotoxicity. However, free PTL relied more heavily on exofacial free thiol interactions to induce cytotoxicity than PTL-loaded micelles; free PTL cytotoxicity was reduced by over twofold when cell surface free thiols were depleted, where PTL-loaded micelle doses were unaffected by cell surface thiol modulation. The physical properties, stability, and efficacy of PTL-loaded PSMA-b-PS micelles support further development of a leukemia therapeutic with greater bioavailability and the potential to eliminate LSCs. PMID:29552235

Visible light-initiated interfacial thiol-norbornene photopolymerization for forming islet surface conformal coating

PubMed Central

Shih, Han; Mirmira, Raghavendra G.; Lin, Chien-Chi

2015-01-01

A cytocompatible visible light-mediated interfacial thiol-norbornene photopolymerization scheme was developed for creating hydrogel conformal coating on pancreatic islets. The step-growth thiol-norbornene reaction affords high consistency and tunability in gel coating thickness. Furthermore, isolated islets coated with thiol-norbornene gel maintained their viability and function in vitro. PMID:26509035

Depletion of intracellular GSH and NPSH by buthionine sulfoximine and diethyl maleate: factors that influence enhancement of aerobic radiation response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varnes, M.E.; Biaglow, J.E.; Roizin-Towle, L.

1984-08-01

Many investigators have observed aerobic sensitization of V79, CHO and A549 (human lung carcinoma) cells upon depletion of GSH using buthionine sulfoximine (BSO). Recently the authors discovered that this aerobic sensitization can be reversed if WR-2721 or N-acetylcysteine is added to the cells just prior to irradiation. Reversal requires that the exogenous thiols be present during the time of irradiation. One possible explanation was that these thiols entered the cells and either increased the pool of cellular nonprotein thiols or reversed the thiol-depleted state by stimulation of GSH synthesis. Cells treated with BSO do not readily regenerate intracellular GSH becausemore » this agent irreversibly inhibits ..gamma..-glutamyl synthetase. They found that addition of WR-2721 or N-acetylcysteine to BSO-treated cells did not affect the rate of regeneration of intracellular GSH. Thus, reversal of the aerobic sensitization of A549 cells by BSO cannot be explained on the basis of intracellular thiol levels alone, or by rapid reversal of BSO inhibition. In addition, diethylmaleate (DEM)-treated cells are considerably different from BSO-treated cells with respect to the ability to regenerate GSH.« less

Surface functionalization of gold nanoparticles using hetero-bifunctional poly(ethylene glycol) spacer for intracellular tracking and delivery

PubMed Central

Shenoy, Dinesh; Fu, Wei; Li, Jane; Crasto, Curtis; Jones, Graham; DiMarzio, Charles; Sridhar, Srinivas; Amiji, Mansoor

2006-01-01

For the development of surface-functionalized gold nanoparticles as cellular probes and delivery agents, we have synthesized hetero-bifunctional poly(ethylene glycol) (PEG, MW 1500) having a thiol group on one terminus and a reactive functional group on the other for use as a flexible spacer. Coumarin, a model fluorescent dye, was conjugated to one end of the PEG spacer and gold nanoparticles were modified with coumarin-PEG-thiol. Surface attachment of coumarin through the PEG spacer decreased the fluorescence quenching effect of gold nanoparticles. The results of cellular cytotoxicity and fluorescence confocal analyses showed that the PEG spacer-modified nanoparticles were essentially non-toxic and could be efficiently internalized in the cells within 1 hour of incubation. Intracellular particle tracking using a Keck 3-D Fusion Microscope System showed that the functionalized gold nanoparticles were rapidly internalized in the cells and localized in the peri-nuclear region. Using the PEG spacer, the gold nano-platform can be conjugated with a variety of biologically relevant ligands such as fluorescent dyes, antibodies, etc in order to target, probe, and induce a stimulus at the target site. PMID:16467923

Thiols in the alphaIIbbeta3 integrin are necessary for platelet aggregation.

PubMed

Manickam, Nagaraj; Sun, Xiuhua; Hakala, Kevin W; Weintraub, Susan T; Essex, David W

2008-07-01

Sulfhydryl groups of platelet surface proteins are important in platelet aggregation. While p-chloromercuribenzene sulphonate (pCMBS) has been used in most studies on platelet surface thiols, the specific thiol-proteins that pCMBS reacts with to inhibit aggregation have not been well defined. Since the thiol-containing P2Y(12) ADP receptor is involved in most types of platelet aggregation, we used the ADP scavenger apyrase and the P2Y(12) receptor antagonist 2-MeSAMP to examine thiol-dependent reactions in the absence of contributions from this receptor. We provide evidence for a non-P2Y(12) thiol-dependent reaction near the final alphaIIbbeta3-dependent events of aggregation. We then used 3-(N-maleimidylpropionyl)biocytin (MPB) and pCMBS to study thiols in alphaIIbbeta3. As previously reported, disruption of the receptor was required to obtain labelling of thiols with MPB. Specificity of labelling for thiols in the alphaIIb and beta3 subunits was confirmed by identification of the purified proteins by mass spectrometry and by inhibition of labelling with 5,5'-dithiobis-(2-nitrobenzoic acid). In contrast to MPB, pCMBS preferentially reacted with thiols in alphaIIbbeta3 and blocked aggregation under physiological conditions. Similarly, pCMBS preferentially inhibited signalling-independent activation of alphaIIbbeta3 by Mn(2+). Our results suggest that the thiols in alphaIIbbeta3 that are blocked by pCMBS are important in the activation of this integrin.

Exploring the core level shift origin of sulfur and thiolates on Pd(111) surfaces.

PubMed

Salvarezza, Roberto Carlos; Carro, Pilar

2015-10-07

Thiol molecules on planar metal surfaces are widely used for building sensing and electronic devices and also as capping agents to protect and to control the size and shape of nanoparticles. In the case of Pd the thiol molecules exhibit a complex behavior because C-S bond scission is possible, resulting in a significant amount of co-adsorbed S. Therefore identification of these species on Pd is a key point for many applications, a task that is usually achieved by XPS. Here we show, from DFT calculations, that the core level shift (CLS) of the S 2p binding energy (BE) of thiol and sulfur on different thiol-Pd(111) surface models strongly depends on the adsorbed or subsurface state of sulfur atoms. Our results reflect the complexity of S 2p BE behavior and contribute to understanding and reanalyzing the experimental data of thiolated Pd surfaces.

Galectin-9 binds to O-glycans on protein disulfide isomerase.

PubMed

Schaefer, Katrin; Webb, Nicholas E; Pang, Mabel; Hernandez-Davies, Jenny E; Lee, Katharine P; Gonzalez, Pascual; Douglass, Martin V; Lee, Benhur; Baum, Linda G

2017-09-01

Changes in the T cell surface redox environment regulate critical cell functions, such as cell migration, viral entry and cytokine production. Cell surface protein disulfide isomerase (PDI) contributes to the regulation of T cell surface redox status. Cell surface PDI can be released into the extracellular milieu or can be internalized by T cells. We have found that galectin-9, a soluble lectin expressed by T cells, endothelial cells and dendritic cells, binds to and retains PDI on the cell surface. While endogenous galectin-9 is not required for basal cell surface PDI expression, exogenous galectin-9 mediated retention of cell surface PDI shifted the disulfide/thiol equilibrium on the T cell surface. O-glycans on PDI are required for galectin-9 binding, and PDI recognition appears to be specific for galectin-9, as galectin-1 and galectin-3 do not bind PDI. Galectin-9 is widely expressed by immune and endothelial cells in inflamed tissues, suggesting that T cells would be exposed to abundant galectin-9, in cis and in trans, in infectious or autoimmune conditions. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Protein Disulfide Isomerase Directly Interacts with β-Actin Cys374 and Regulates Cytoskeleton Reorganization*

PubMed Central

Sobierajska, Katarzyna; Skurzynski, Szymon; Stasiak, Marta; Kryczka, Jakub; Cierniewski, Czeslaw S.; Swiatkowska, Maria

2014-01-01

Recent studies support the role of cysteine oxidation in actin cytoskeleton reorganization during cell adhesion. The aim of this study was to explain whether protein disulfide isomerase (PDI) is responsible for the thiol-disulfide rearrangement in the β-actin molecule of adhering cells. First, we showed that PDI forms a disulfide-bonded complex with β-actin with a molecular mass of 110 kDa. Specific interaction of both proteins was demonstrated by a solid phase binding assay, surface plasmon resonance analysis, and immunoprecipitation experiments. Second, using confocal microscopy, we found that both proteins colocalized when spreading MEG-01 cells on fibronectin. Colocalization of PDI and β-actin could be abolished by the membrane-permeable sulfhydryl blocker, N-ethylmaleimide, by the RGD peptide, and by anti-αIIbβ3 antibodies. Consequently, down-regulation of PDI expression by antisense oligonucleotides impaired the spreading of cells and initiated reorganization of the cytoskeleton. Third, because of transfection experiments followed by immunoprecipitation and confocal analysis, we provided evidence that PDI binds to the β-actin Cys374 thiol. Formation of the β-actin-PDI complex was mediated by integrin-dependent signaling in response to the adhesion of cells to the extracellular matrix. Our data suggest that PDI is released from subcellular compartments to the cytosol and translocated toward the periphery of the cell, where it forms a disulfide bond with β-actin when MEG-01 cells adhere via the αIIbβ3 integrin to fibronectin. Thus, PDI appears to regulate cytoskeletal reorganization by the thiol-disulfide exchange in β-actin via a redox-dependent mechanism. PMID:24415753

High-Yield Synthesis and Applications of Anisotropic Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Vigderman, Leonid

This work will describe research directed towards the synthesis of anisotropic gold nanoparticles as well as their functionalization and biological applications. The thesis will begin by describing a new technique for the high-yield synthesis of gold nanorods using hydroquinone as a reducing agent. This addresses important limitations of the traditional nanorod synthesis including low yield of gold ions conversion to metallic form and inability to produce rods with longitudinal surface plasmon peak above 850 nm. The use of hydroquinone was also found to improve the synthesis of gold nanowires via the nanorod-seed mediated procedure developed in our lab. The thesis will next present the synthesis of novel starfruitshaped nanorods, mesorods, and nanowires using a modified nanorod-seed mediated procedure. The starfruit particles displayed increased activity as surfaceenhanced Raman spectroscopy (SERS) substrates as compared to smooth structures. Next, a method for the functionalization of gold nanorods using a cationic thiol, 16-mercaptohexadecyltrimethylammonium bromide (MTAB), will be described. By using this thiol, we were able to demonstrate the complete removal of toxic surfactant from the nanorods and were also able to precisely quantify the grafting density of thiol molecules on the nanorod surface through a combination of several analytical techniques. Finally, this thesis will show that MTABfunctionalized nanorods are nontoxic and can be taken up in extremely high numbers into cancer cells. The thesis will conclude by describing the surprising uptake of larger mesorods and nanowires functionalized with MTAB into cells in high quantities.

Oriented and covalent immobilization of target molecules to solid supports: synthesis and application of a light-activatable and thiol-reactive cross-linking reagent.

PubMed

Collioud, A; Clémence, J F; Sänger, M; Sigrist, H

1993-01-01

Light-dependent oriented and covalent immobilization of target molecules has been achieved by combining two modification procedures: light-dependent coupling of target molecules to inert surfaces and thiol-selective reactions occurring at macromolecule or substrate surfaces. For immobilization purposes the heterobifunctional reagent N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl]-4-maleimidobutyr amide was synthesized and chemically characterized. The photosensitivity of the carbene-generating reagent and its reactivity toward thiols were ascertained. Light-induced cross-linking properties of the reagent were documented (i) by reacting first the maleimide function with a thiolated surface, followed by carbene insertion into applied target molecules, (ii) by photochemical coupling of the reagent to an inert support followed by thermochemical reactions with thiol functions, and (iii) by thermochemical modification of target molecules prior to carbene-mediated insertion into surface materials. Procedures mentioned led to light-dependent covalent immobilization of target molecules including amino acids, a synthetic peptide, and antibody-derived F(ab') fragments. Topically selective, light-dependent immobilization was attained with the bifunctional reagent by irradiation of coated surfaces through patterned masks. Glass and polystyrene served as substrates. Molecular orientation is asserted by inherently available or selectively introduced terminal thiol functions in F(ab') fragments and synthetic polypeptides, respectively.

Thiol-ene immobilisation of carbohydrates onto glass slides as a simple alternative to gold-thiol monolayers, amines or lipid binding.

PubMed

Biggs, Caroline I; Edmondson, Steve; Gibson, Matthew I

2015-01-01

Carbohydrate arrays are a vital tool in studying infection, probing the mechanisms of bacterial, viral and toxin adhesion and the development of new treatments, by mimicking the structure of the glycocalyx. Current methods rely on the formation of monolayers of carbohydrates that have been chemically modified with a linker to enable interaction with a functionalised surface. This includes amines, biotin, lipids or thiols. Thiol-addition to gold to form self-assembled monolayers is perhaps the simplest method for immobilisation as thiolated glycans are readily accessible from reducing carbohydrates in a single step, but are limited to gold surfaces. Here we have developed a quick and versatile methodology which enables the use of thiolated carbohydrates to be immobilised as monolayers directly onto acrylate-functional glass slides via a 'thiol-ene'/Michael-type reaction. By combining the ease of thiol chemistry with glass slides, which are compatible with microarray scanners this offers a cost effective, but also useful method to assemble arrays.

Heavy metal ion removal by thiol functionalized aluminum oxide hydroxide nanowhiskers

NASA Astrophysics Data System (ADS)

Xia, Zhiyong; Baird, Lance; Zimmerman, Natasha; Yeager, Matthew

2017-09-01

In this study, we developed a cost effective method of using thiol functionalized γ-aluminum oxide hydroxide (γ-AlOOH) filters for removing three key heavy metals from water: mercury, lead, and cadmium under non-concomitant conditions. Compared to non-thiol treated γ-AlOOH filters, the introduction of thiol functional groups greatly improved the heavy metal removal efficiency under both static and dynamic filtration conditions. The adsorption kinetics of thiol functionalized γ-AlOOH were investigated using the Lagergren first order and pseudo-second order kinetics models; whereas the isothermal adsorption behavior of these membranes was revealed through the Langmuir and Freundlich models. Heavy metal concentration was quantified by Inductively Coupled Plasma-Mass Spectroscopy, and the thiol level on γ-AlOOH surface was measured by a colorimetric assay using Ellman's reagent. X-ray photoelectron spectroscopy was used to further address the surface sulfur state on the membranes after heavy metal exposure. Mechanisms for heavy metal adsorption were also discussed.

Modifying surface resistivity and liquid moisture management property of keratin fibers through thiol-ene click reactions.

PubMed

Yu, Dan; Cai, Jackie Y; Church, Jeffrey S; Wang, Lijing

2014-01-22

This paper reports on a new method for improving the antistatic and liquid moisture management properties of keratinous materials. The method involves the generation of thiols by controlled reduction of cystine disulfide bonds in keratin with tris(2-carboxyethyl) phosphine hydrochloride and subsequent grafting of hydrophilic groups onto the reduced keratin by reaction with an acrylate sulfonate or acrylamide sulfonate through thiol-ene click chemistry. The modified substrates were characterized with Raman spectroscopy and scanning electron microscopy and evaluated for their performance changes in liquid moisture management, surface resistivity, and wet burst strength. The results have revealed that the thiol-acrylate reaction is more efficient than the thiol-acrylamide reaction, and the keratinous substrate modified with an acrylate sulfonate salt exhibits significantly improved antistatic and liquid moisture management properties.

A chromenoquinoline-based fluorescent off-on thiol probe for bioimaging.

PubMed

Kand, Dnyaneshwar; Kalle, Arunasree Marasanapalli; Varma, Sreejith Jayasree; Talukdar, Pinaki

2012-03-11

A new chromenoquinoline-based fluorescent off-on thiol probe 2 is reported. In aqueous buffer solutions at physiological pH, the probe exhibited 223-fold enhancement in fluorescence intensity by a Michael addition of cysteine to the maleimide appended to a chromenoquinoline. Cell permeability and live cell imaging of thiols are also demonstrated. This journal is © The Royal Society of Chemistry 2012

A lysosome-targetable turn-on fluorescent probe for the detection of thiols in living cells based on a 1,8-naphthalimide derivative

NASA Astrophysics Data System (ADS)

Liang, Beibei; Wang, Baiyan; Ma, Qiujuan; Xie, Caixia; Li, Xian; Wang, Suiping

2018-03-01

Biological thiols, like cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), play crucial roles in biological systems and in lysosomal processes. Highly selective probes for detecting biological thiols in lysomes of living cells are rare. In this work, a lysosome-targetable turn-on fluorescent probe for the detection of thiols in living cells was designed and synthesized based on a 1,8-naphthalimide derivative. The probe has a 4-(2-aminoethyl)morpholine unit as a lysosome-targetable group and an acrylate group as the thiol recognition unit as well as a fluorescence quencher. In the absence of biothiols, the probe displayed weak fluorescence due to the photoinduced electron transfer (PET) process. Upon the addition of biothiols, the probe exhibited an enhanced fluorescence emission centered at 550 nm due to cleavage of the acrylate moiety. The probe had high selectivity toward biothiols. Moreover, the probe features fast response time, excitation in the visible region and ability of working in a wide pH range. The linear response range covers a concentration range of Cys from 1.5 × 10- 7 to 1.0 × 10- 5 mol·L- 1 and the detection limit is 6.9 × 10- 8 mol·L- 1 for Cys. The probe has been successfully applied to the confocal imaging of biothiols in lysosomes of A549 cells with low cell toxicity. Furthermore, the method was successfully applied to the determination of thiols in a complex multicomponent mixture such as human serum, which suggests our proposed method has great potential for diagnostic purposes. All of such good properties prove it can be used to monitor biothiols in lysosomes of living cells and to be a good fluorescent probe for the selective detection of thiols.

Modification of Ag nanoparticles with mixed thiols for improved SERS detection of poorly adsorbing target molecules: detection of MDMA.

PubMed

Stewart, Alan; Bell, Steven E J

2011-04-21

Here we report an example of a mixed thiol monolayer on the surface of Ag nanoparticles which promotes adsorption and quantitative SERS detection of 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy"); the thiols in the mixed monolayers act synergistically since MDMA does not adsorb onto colloids modified with either of the thiols separately. © The Royal Society of Chemistry 2011

Necrotic and apoptotic cell death induced by Captan on Saccharomyces cerevisiae.

PubMed

Scariot, Fernando J; Jahn, Luciane; Delamare, Ana Paula L; Echeverrigaray, Sergio

2017-08-01

Captan is one of the most widely used broad-spectrum fungicide applied to control several early and late diseases of grapes, apples, and other fruits and vegetables, and as other phthalimide fungicides is defined as a multisite compound with thiol-reactivity. Captan can affect non-target organisms as yeasts, modifying microbial populations and fermentation processes. In this study, we asked whether Captan thiol-reactivity and other mechanisms are involved in acute Captan-induced cell death on aerobic growing Saccharomyces cerevisiae. Thus for, we analyze cellular protein and non-protein thiols, cell membrane integrity, reactive oxygen species accumulation, phosphatidylserine externalization, and apoptotic mutants behavior. The results showed that when submitted to acute Captan treatment most cells lost their membrane integrity and died by necrosis due to Captan reaction with thiols. However, part of the cells, even maintaining their membrane integrity, lost their culture ability. These cells showed an apoptotic behavior that may be the result of non-protein thiol depletion and consequent increase of reactive oxygen species (ROS). ROS accumulation triggers a metacaspase-dependent apoptotic cascade, as shown by the higher viability of the yca1-deleted mutant. Together, necrosis and apoptosis are responsible for the high mortality detected after acute Captan treatment of aerobically growing cells of S. cerevisiae.

Functional thiols as repair and doping agents of defective MoS2 monolayers

NASA Astrophysics Data System (ADS)

Förster, Anja; Gemming, Sibylle; Seifert, Gotthard

2018-06-01

Recent experimental and theoretical studies indicate that thiols (R-SH) can be used to repair sulfur vacancy defects in MoS2 monolayers (MLs). This density functional theory study investigates how the thiol repair mechanism process can be used to dope MoS2 MLs. Fluorinated thiols as well as amine-containing ones are used to p- and n-dope the MoS2 ML, respectively. It is shown that functional groups are only physisorbed on the repaired MoS2 surface. This explains the reversible doping with fluorinated thiols.

Programmable Liquid Crystal Elastomers Prepared by Thiol-Ene Photopolymerization (Postprint)

DTIC Science & Technology

2015-08-17

defect forms a 2D wrinkling pattern that leads to an areal contraction (Figure 4c,d). Both of these films return to a largely flat state on cooling...photopolymerization. ■ MATERIALS AND METHODS RM82 (1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylben- zene) was purchased from Synthon Chemicals. 1,2...noted. Liquid crystal cells were prepared using methods described elsewhere.10 Briefly for cells patterned using rubbed surfaces, Elvamide was

Nitroolefin-based BODIPY as a novel water-soluble ratiometric fluorescent probe for detection of endogenous thiols

NASA Astrophysics Data System (ADS)

Kang, Jin; Huo, Fangjun; Chao, Jianbin; Yin, Caixia

2018-04-01

Small molecule biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play many crucial roles in physiological processes. In this work, we have prepared a nitroolefin-based BODIPY fluorescent probe with excellent water solubility for detection thiols, which displayed ratiometric fluorescent signal for thiols. Incorporation of a nitroolefin unit to the BODIPY dye would transform it into a strong Michael acceptor, which would be highly susceptible to sulfhydryl nucleophiles. This probe shows an obvious ratio change upon response with thiols, an increase of the emission at 517 nm along with a concomitant decrease of fluorescence peak at 573 nm. Moreover, these successes of intracellular imaging experiments in A549 cells indicated that this probe is suitable for imaging of ex-/endogenous thiols in living cells.

Reversal to cisplatin sensitivity in recurrent human ovarian cancer cells by NCX-4016, a nitro derivative of aspirin

PubMed Central

Bratasz, Anna; Weir, Nathan M.; Parinandi, Narasimham L.; Zweier, Jay L.; Sridhar, Rajagopalan; Ignarro, Louis J.; Kuppusamy, Periannan

2006-01-01

Ovarian cancer is a gynecological malignancy that is commonly treated by cytoreductive surgery followed by cisplatin treatment. However, the cisplatin treatment, although successful initially, is not effective in the treatment of the recurrent disease that invariably surfaces within a few months of the initial treatment. The refractory behavior is attributed to the increased levels of cellular thiols apparently caused by the cisplatin treatment. This observation prompted us to choose a cytotoxic drug whose activity is potentiated by cellular thiols with enhanced specificity toward the thiol-rich cisplatin-resistant cells. We used NCX-4016 [2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester], a derivative of aspirin containing a nitro group that releases nitric oxide in a sustained fashion for several hours in cells and in vivo, and we studied its cytotoxic efficacy against human ovarian cancer cells (HOCCs). Cisplatin-sensitive and cisplatin-resistant (CR) HOCCs were treated with 100 μM NCX-4016 for 6 h, and/or 0.5 μg/ml cisplatin for 1 h and assayed for clonogenecity. NCX-4016 significantly reduced the surviving fractions of cisplatin-sensitive (63 ± 6%) and CR (70 ± 10%) HOCCs. NCX-4016 also caused a 50% reduction in the levels of cellular glutathione in CR HOCCs. Treatment of cells with NCX-4016 followed by cisplatin showed a significantly greater extent of toxicity when compared with treatment of cells with NCX-4016 or cisplatin alone. In conclusion, this study showed that NCX-4016 is a potential inhibitor of the proliferation of CR HOCCs and thus might specifically kill cisplatin-refractory cancer cells in patients with recurrent ovarian cancer. PMID:16497833

“Turn-on” fluorescence probe integrated polymer nanoparticles for sensing biological thiol molecules

NASA Astrophysics Data System (ADS)

Ang, Chung Yen; Tan, Si Yu; Lu, Yunpeng; Bai, Linyi; Li, Menghuan; Li, Peizhou; Zhang, Quan; Selvan, Subramanian Tamil; Zhao, Yanli

2014-11-01

A ``turn-on'' thiol-responsive fluorescence probe was synthesized and integrated into polymeric nanoparticles for sensing intracellular thiols. There is a photo-induced electron transfer process in the off state of the probe, and this process is terminated upon the reaction with thiol compounds. Configuration interaction singles (CIS) calculation was performed to confirm the mechanism of this process. A series of sensing studies were carried out, showing that the probe-integrated nanoparticles were highly selective towards biological thiol compounds over non-thiolated amino acids. Kinetic studies were also performed to investigate the relative reaction rate between the probe and the thiolated amino acids. Subsequently, the Gibbs free energy of the reactions was explored by means of the electrochemical method. Finally, the detection system was employed for sensing intracellular thiols in cancer cells, and the sensing selectivity could be further enhanced with the use of a cancer cell-targeting ligand in the nanoparticles. This development paves a path for the sensing and detection of biological thiols, serving as a potential diagnostic tool in the future.

Method of making gold thiolate and photochemically functionalized microcantilevers

DOEpatents

Boiadjiev, Vassil I [Knoxville, TN; Brown, Gilbert M [Knoxville, TN; Pinnaduwage, Lal A [Knoxville, TN; Thundat, Thomas G [Knoxville, TN; Bonnesen, Peter V [Knoxville, TN; Goretzki, Gudrun [Nottingham, GB

2009-08-25

Highly sensitive sensor platforms for the detection of specific reagents, such as chromate, gasoline and biological species, using microcantilevers and other microelectromechanical systems (MEMS) whose surfaces have been modified with photochemically attached organic monolayers, such as self-assembled monolayers (SAM), or gold-thiol surface linkage are taught. The microcantilever sensors use photochemical hydrosilylation to modify silicon surfaces and gold-thiol chemistry to modify metallic surfaces thereby enabling individual microcantilevers in multicantilever array chips to be modified separately. Terminal vinyl substituted hydrocarbons with a variety of molecular recognition sites can be attached to the surface of silicon via the photochemical hydrosilylation process. By focusing the activating UV light sequentially on selected silicon or silicon nitride hydrogen terminated surfaces and soaking or spotting selected metallic surfaces with organic thiols, sulfides, or disulfides, the microcantilevers are functionalized. The device and photochemical method are intended to be integrated into systems for detecting specific agents including chromate groundwater contamination, gasoline, and biological species.

Modification of porous silicon rugate filters through thiol-yne photochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soeriyadi, Alexander H., E-mail: alexander.soeriyadi@unsw.edu.au; Zhu, Ying, E-mail: alexander.soeriyadi@unsw.edu.au; Gooding, J. Justin, E-mail: justin.gooding@unsw.edu.au

2014-02-24

Porous silicon (PSi) has a considerable potential as biosensor platform. In particular, the ability to modify the surface chemistry of porous silicon is of interest. Here we present a generic method to modify the surface of porous silicon through thiol-yne photochemistry initiated by a radical initiator. Firstly, a freshly etched porous silicon substrate is modified through thermal hydrosilylation with 1,8-nonadiyne to passivate the surface and introduce alkyne functionalities. The alkyne functional surface could then be further reacted with thiol species in the presence of a radical initiator and UV light. Functionalization of the PSi rugate filter is followed with opticalmore » reflectivity measurements as well as high resolution X-ray photoelectron spectroscopy (XPS)« less

The application of polythiol molecules for protein immobilisation on sensor surfaces.

PubMed

Kyprianou, Dimitris; Guerreiro, Antonio R; Nirschl, Martin; Chianella, Iva; Subrahmanyam, Sreenath; Turner, Anthony P F; Piletsky, Sergey

2010-01-15

The immobilisation of bio-receptors on transducer surfaces is a key step in the development of biosensors. The immobilisation needs to be fast, cheap and most importantly should not affect the biorecognition activity of the immobilised receptor. The development of a protocol for biomolecule immobilisation onto a surface plasmon resonance (SPR) sensor surface using inexpensive polythiol compounds is presented here. The method used here is based on the reaction between primary amines and thioacetal groups, formed upon reaction of o-phthaldialdehyde (OPA) and thiol compounds. The self-assembled thiol monolayers were characterised using contact angle and XPS. The possibility to immobilise proteins on monolayers was assessed by employing BSA as a model protein. For the polythiol layers exhibiting the best performance, a general protocol was optimised suitable for the immobilisation of enzymes and antibodies such as anti-prostate specific antigen (anti-PSA) and anti Salmonella typhimurium. The kinetic data was obtained for PSA binding to anti-PSA and for S. typhimurium cells with a detection limit of 5x10(6) cells mL(-1) with minimal non-specific binding of other biomolecules. These findings make this technique a very promising alternative for amine coupling compared to peptide bond formation. Additionally, it offers opportunity for immobilising proteins (even those with low isoelectric point) on neutral polythiol layers without any activation step. Copyright 2009 Elsevier B.V. All rights reserved.

A Novel Oxidative Stress Mediator in Acute Appendicitis: Thiol/Disulphide Homeostasis

PubMed Central

Turan, Umit; Kuvvetli, Adnan; Kilavuz, Huseyin; Karakaya, Burak; Ozaltun, Pınar; Alısık, Murat; Erel, Ozcan

2016-01-01

Aim. To investigate the role of a novel oxidative stress marker, thiol/disulphide homeostasis, in patients diagnosed with acute appendicitis (AA). Methods. In this study, seventy-one (43 male and 28 female) patients diagnosed with AA and 71 (30 male and 41 female) healthy volunteers were included. Age, gender, body mass index (BMI), haemoglobin (Hb), white blood cell (WBC), c-reactive protein (CRP), and thiol/disulphide homeostasis parameters (native thiol, total thiol, disulphide, disulphide/native thiol, native thiol/total thiol, and disulphide/total thiol ratios) were compared between the groups. Thiol/disulphide homeostasis was determined by a newly developed method by Erel and Neselioglu. Results. The native thiol, total thiol, and the native thiol/total thiol ratio levels were statistically significantly decreased in the AA compared with the control group (p < 0.001). Disulphide level and the ratios of disulphide/native thiol and disulphide/total thiol were higher in the AA group than in the control group (p < 0.001). There was a negative correlation of CRP with native thiol, total thiol, and native thiol/total thiol ratio while there was a positive correlation of CRP with disulphide/native thiol and disulphide/total thiol in the AA group. In the stepwise regression model, risk factors as disulphide/native thiol (OR = 1.368; p = 0.018) and CRP (OR = 1.635; p = 0.003) were determined as predictors of perforated appendicitis compared to the nonperforated group. Conclusion. This is the first study examining the thiol/disulphide homeostasis as a diagnostic aid in AA and establishing thiol/disulphide homeostatis balance shifted towards the disulphide formation due to thiol oxidation. Further studies are needed to optimize the use of this novel oxidative stress marker in AA. PMID:27642237

Thiol-ene mediated neoglycosylation of collagen patches: a preliminary study.

PubMed

Russo, Laura; Battocchio, Chiara; Secchi, Valeria; Magnano, Elena; Nappini, Silvia; Taraballi, Francesca; Gabrielli, Luca; Comelli, Francesca; Papagni, Antonio; Costa, Barbara; Polzonetti, Giovanni; Nicotra, Francesco; Natalello, Antonino; Doglia, Silvia M; Cipolla, Laura

2014-02-11

Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the covalent surface modification of collagen-based matrices with small carbohydrate epitopes has been scarcely investigated. We report thereby the development of an efficient procedure for the chemoselective neoglycosylation of collagen matrices (patches) via a thiol-ene approach, between alkene-derived monosaccharides and the thiol-functionalized material surface. Synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), Fourier transform-infrared (FT-IR), and enzyme-linked lectin assay (ELLA) confirmed the effectiveness of the collagen neoglycosylation. Preliminary biological evaluation in osteoarthritic models is reported. The proposed methodology can be extended to any thiolated surface for the development of smart biomaterials for innovative approaches in regenerative medicine.

A periodic mixed gaussians-plane waves DFT study on simple thiols on Au(111): adsorbate species, surface reconstruction, and thiols functionalization.

PubMed

Rajaraman, Gopalan; Caneschi, Andrea; Gatteschi, Dante; Totti, Federico

2011-03-07

Here we present DFT calculations based on a periodic mixed gaussians/plane waves approach to study the energetics, structure, bonding of SAMs of simple thiols on Au(111). Several open issues such as structure, bonding and the nature of adsorbate are taken into account. We started with methyl thiols (MeSH) on Au(111) to establish the nature of the adsorbate. We have considered several structural models embracing the reconstructed surface scenario along with the MeS˙-Au(ad)-MeS˙ type motif put forward in recent years. Our calculations suggest a clear preference for the homolytic cleavage of the S-H bond leading to a stable MeS˙ on a gold surface. In agreement with the recent literature studies, the reconstructed models of the MeS˙ species are found to be energetically preferred over unreconstructed models. Besides, our calculations reveal that the model with 1:2 Au(ad)/thiols ratio, i.e. MeS˙-Au(ad)-MeS˙, is energetically preferred compared to the clean and 1:1 ratio models, in agreement with the experimental and theoretical evidences. We have also performed Molecular Orbital/Natural Bond Orbital, MO/NBO, analysis to understand the electronic structure and bonding in different structural motifs and many useful insights have been gained. Finally, the studies have then been extended to alkyl thiols of the RSR' (R, R' = Me, Et and Ph) type and here our calculations again reveal a preference for the RS˙ type species adsorption for clean as well as for reconstructed 1:2 Au(ad)/thiols ratio models.

A lysosome-targetable turn-on fluorescent probe for the detection of thiols in living cells based on a 1,8-naphthalimide derivative.

PubMed

Liang, Beibei; Wang, Baiyan; Ma, Qiujuan; Xie, Caixia; Li, Xian; Wang, Suiping

2018-03-05

Biological thiols, like cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), play crucial roles in biological systems and in lysosomal processes. Highly selective probes for detecting biological thiols in lysomes of living cells are rare. In this work, a lysosome-targetable turn-on fluorescent probe for the detection of thiols in living cells was designed and synthesized based on a 1,8-naphthalimide derivative. The probe has a 4-(2-aminoethyl)morpholine unit as a lysosome-targetable group and an acrylate group as the thiol recognition unit as well as a fluorescence quencher. In the absence of biothiols, the probe displayed weak fluorescence due to the photoinduced electron transfer (PET) process. Upon the addition of biothiols, the probe exhibited an enhanced fluorescence emission centered at 550nm due to cleavage of the acrylate moiety. The probe had high selectivity toward biothiols. Moreover, the probe features fast response time, excitation in the visible region and ability of working in a wide pH range. The linear response range covers a concentration range of Cys from 1.5×10 -7 to 1.0×10 -5 mol·L -1 and the detection limit is 6.9×10 -8 mol·L -1 for Cys. The probe has been successfully applied to the confocal imaging of biothiols in lysosomes of A549 cells with low cell toxicity. Furthermore, the method was successfully applied to the determination of thiols in a complex multicomponent mixture such as human serum, which suggests our proposed method has great potential for diagnostic purposes. All of such good properties prove it can be used to monitor biothiols in lysosomes of living cells and to be a good fluorescent probe for the selective detection of thiols. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of Self-Assembled Monolayers of Different Wettabilities To Study Surface Selection and Primary Adhesion Processes of Green Algal (Enteromorpha) Zoospores

PubMed Central

Callow, Maureen E.; Callow, J. A.; Ista, Linnea K.; Coleman, Sarah E.; Nolasco, Aleece C.; López, Gabriel P.

2000-01-01

We investigated surface selection and adhesion of motile zoospores of a green, macrofouling alga (Enteromorpha) to self-assembled monolayers (SAMs) having a range of wettabilities. The SAMs were formed from alkyl thiols terminated with methyl (CH3) or hydroxyl (OH) groups or mixtures of CH3- and OH-terminated alkyl thiols and were characterized by measuring the advancing contact angles and by X-ray photoelectron spectroscopy. There was a positive correlation between the number of spores that attached to the SAMs and increasing contact angle (hydrophobicity). Moreover, the sizes of the spore groups (adjacent spores touching) were larger on the hydrophobic SAMs. Video microscopy of a patterned arrangement of SAMs showed that more zoospores were engaged in swimming and “searching” above the hydrophobic sectors than above the hydrophilic sectors, suggesting that the cells were able to “sense” that the hydrophobic surfaces were more favorable for settlement. The results are discussed in relation to the attachment of microorganisms to substrata having different wettabilities. PMID:10919777

Cancer cell-selective killing polymer/copper combination.

PubMed

He, Huacheng; Altomare, Diego; Ozer, Ufuk; Xu, Hanwen; Creek, Kim; Chen, Hexin; Xu, Peisheng

2016-01-01

Chemotherapy has been adopted for cancer treatment for decades. However, its efficacy and safety are frequently compromised by the multidrug-resistance of cancer cells and the poor cancer cell selectivity of anticancer drugs. Hereby, we report a combination of a pyridine-2-thiol containing polymer and copper which can effectively kill a wide spectrum of cancer cells, including drug resistant cancer cells, while sparing normal cells. The polymer nanoparticle enters cells via an exofacial thiol facilitated route, and releases active pyridine-2-thiol with the help of intracellularly elevated glutathione (GSH). Due to their high GSH level, cancer cells are more vulnerable to the polymer/copper combination. In addition, RNA microarray analysis revealed that the treatment can reverse cancer cells' upregulated oncogenes (CIRBP and STMN1) and downregulated tumor suppressor genes (CDKN1C and GADD45B) to further enhance the selectivity for cancer cells.

Implementation of molecularly imprinted polymer beads for surface enhanced Raman detection.

PubMed

Kamra, Tripta; Zhou, Tongchang; Montelius, Lars; Schnadt, Joachim; Ye, Lei

2015-01-01

Molecularly imprinted polymers (MIPs) have a predesigned molecular recognition capability that can be used to build robust chemical sensors. MIP-based chemical sensors allow label-free detection and are particularly interesting due to their simple operation. In this work we report the use of thiol-terminated MIP microspheres to construct surfaces for detection of a model organic analyte, nicotine, by surface enhanced Raman scattering (SERS). The nicotine-imprinted microspheres are synthesized by RAFT precipitation polymerization and converted into thiol-terminated microspheres through aminolysis. The thiol groups on the MIP surface allow the microspheres to be immobilized on a gold-coated substrate. Three different strategies are investigated to achieve surface enhanced Raman scattering in the vicinity of the imprinted sites: (1) direct sputtering of gold nanoparticles, (2) immobilization of gold colloids through the MIP's thiol groups, and (3) trapping of the MIP microspheres in a patterned SERS substrate. For the first time we show that large MIP microspheres can be turned into selective SERS surfaces through the three different approaches of assembly. The MIP-based sensing surfaces are used to detect nicotine to demonstrate the proof of concept. As synthesis and surface functionalization of MIP microspheres and nanoparticles are well established, the methods reported in this work are handy and efficient for constructing label-free chemical sensors, in particular for those based on SERS detection.

Mechanism of protein decarbonylation.

PubMed

Wong, Chi-Ming; Marcocci, Lucia; Das, Dividutta; Wang, Xinhong; Luo, Haibei; Zungu-Edmondson, Makhosazane; Suzuki, Yuichiro J

2013-12-01

Ligand/receptor stimulation of cells promotes protein carbonylation that is followed by the decarbonylation process, which might involve thiol-dependent reduction (C.M. Wong et al., Circ. Res. 102:301-318; 2008). This study further investigated the properties of this protein decarbonylation mechanism. We found that the thiol-mediated reduction of protein carbonyls is dependent on heat-labile biologic components. Cysteine and glutathione were efficient substrates for decarbonylation. Thiols decreased the protein carbonyl content, as detected by 2,4-dinitrophenylhydrazine, but not the levels of malondialdehyde or 4-hydroxynonenal protein adducts. Mass spectrometry identified proteins that undergo thiol-dependent decarbonylation, which include peroxiredoxins. Peroxiredoxin-2 and -6 were carbonylated and subsequently decarbonylated in response to the ligand/receptor stimulation of cells. siRNA knockdown of glutaredoxin inhibited the decarbonylation of peroxiredoxin. These results strengthen the concept that thiol-dependent decarbonylation defines the kinetics of protein carbonylation signaling. © 2013 Elsevier Inc. All rights reserved.

Mechanism of protein decarbonylation

PubMed Central

Wong, Chi-Ming; Marcocci, Lucia; Das, Dividutta; Wang, Xinhong; Luo, Haibei; Zungu-Edmondson, Makhosazane; Suzuki, Yuichiro J.

2013-01-01

Ligand/receptor-stimulation of cells promotes protein carbonylation that is followed by the decarbonylation process, which might involve thiol-dependent reduction (Wong et al., Circ. Res. 102 301-318, 2008). The present study further investigated the properties of this protein decarbonylation mechanism. We found that the thiol-mediated reduction of protein carbonyls is dependent on heat-labile biologic components. Cysteine and glutathione were found to be efficient substrates for decarbonylation. Thiols decreased the protein carbonyl content, as detected by 2,4-dinitrophenylhydrazine, but not the levels of malondialdehyde or 4-hydroxynonenal protein adducts. Mass spectrometry identified proteins that undergo thiol-dependent decarbonylation, which include peroxiredoxins. Peroxiredoxins-2 and -6 were found to be carbonylated and subsequent decarbonylated in response to the ligand/receptor-stimulation of cells. siRNA knockdown of glutaredoxin inhibited the decarbonylation of peroxiredoxin. These results strengthen the concept that thiol-dependent decarbonylation defines the kinetics of protein carbonylation signaling. PMID:24044890

Thiol trapping and metabolic redistribution of sulfur metabolites enable cells to overcome cysteine overload

PubMed Central

Deshpande, Anup Arunrao; Bhatia, Muskan; Laxman, Sunil; Bachhawat, Anand Kumar

2017-01-01

Cysteine is an essential requirement in living organisms. However, due to its reactive thiol side chain, elevated levels of intracellular cysteine can be toxic and therefore need to be rapidly eliminated from the cellular milieu. In mammals and many other organisms, excess cysteine is believed to be primarily eliminated by the cysteine dioxygenase dependent oxidative degradation of cysteine, followed by the removal of the oxidative products. However, other mechanisms of tackling excess cysteine are also likely to exist, but have not thus far been explored. In this study, we use Saccharomyces cerevisiae, which naturally lacks a cysteine dioxygenase, to investigate mechanisms for tackling cysteine overload. Overexpressing the high affinity cysteine transporter, YCT1, enabled yeast cells to rapidly accumulate high levels of intracellular cysteine. Using targeted metabolite analysis, we observe that cysteine is initially rapidly interconverted to non-reactive cystine in vivo. A time course revealed that cells systematically convert excess cysteine to inert thiol forms; initially to cystine, and subsequently to cystathionine, S-Adenosyl-L-homocysteine (SAH) and S-Adenosyl L-methionine (SAM), in addition to eventually accumulating glutathione (GSH) and polyamines. Microarray based gene expression studies revealed the upregulation of arginine/ornithine biosynthesis a few hours after the cysteine overload, and suggest that the non-toxic, non-reactive thiol based metabolic products are eventually utilized for amino acid and polyamine biogenesis, thereby enabling cell growth. Thus, cells can handle potentially toxic amounts of cysteine by a combination of thiol trapping, metabolic redistribution to non-reactive thiols and subsequent consumption for anabolism. PMID:28435838

Cell adhesion pattern created by OSTE polymers.

PubMed

Liu, Wenjia; Li, Yiyang; Ding, Xianting

2017-04-24

Engineering surfaces with functional polymers is a crucial issue in the field of micro/nanofabrication and cell-material interface studies. For many applications of surface patterning, it does not need cells to attach on the whole surface. Herein, we introduce a novel polymer fabrication protocol of off-stoichiometry thiol-ene (OSTE) polymers to create heterogeneity on the surface by utilizing 3D printing and soft-lithography. By choosing two OSTE polymers with different functional groups, we create a pattern where only parts of the surface can facilitate cell adhesion. We also study the hydrophilic property of OSTE polymers by mixing poly(ethylene glycol) (PEG) directly with pre-polymers and plasma treatments afterwards. Moreover, we investigate the effect of functional groups' excess ratio and hydrophilic property on the cell adhesion ability of OSTE polymers. The results show that the cell adhesion ability of OSTE materials can be tuned within a wide range by the coupling effect of functional groups' excess ratio and hydrophilic property. Meanwhile, by mixing PEG with pre-polymers and undergoing oxygen plasma treatment afterward can significantly improve the hydrophilic property of OSTE polymers.

Enhancing the biocompatibility of the polyurethane methacrylate and off-stoichiometry thiol-ene polymers by argon and nitrogen plasma treatment.

PubMed

Chen, Tiam Foo; Siow, Kim Shyong; Ng, Pei Yuen; Majlis, Burhanuddin Yeop

2017-10-01

Our studies focused on improving the biocompatibility properties of two microfluidic prototyping substrates i.e. polyurethane methacrylate (PUMA) and off-stoichiometry thiol-ene (OSTE-80) polymer by Ar and N 2 plasma treatment. The contact angle (CA) measurement showed that both plasma treatments inserted oxygen and nitrogen moieties increased the surface energy and hydrophilicity of PUMA and OSTE-80 polymer which corresponded to an increase of nitrogen to carbon ratios (N/C), as measured by XPS, to provide a conducive environment for cell attachments and proliferation. Under the SEM observation, the surface topography of PUMA and OSTE-80 polymer showed minimal changes after the plasma treatments. Furthermore, ageing studies showed that plasma-treated PUMA and OSTE-80 polymer had stable hydrophilicity and nitrogen composition during storage in ambient air for 15days. After in vitro cell culture of human umbilical vein endothelial cells (HUVECs) on these surfaces for 24h and 72h, both trypan blue and alamar blue assays indicated that PUMA and OSTE-80 polymer treated with N 2 plasma had the highest viability and proliferation. The polar nitrogen moieties, specifically amide groups, encouraged the HUVECs adhesion on the plasma-treated PUMA and OSTE-80 surfaces. Interestingly, PUMA polymer treated with Ar and N 2 plasma showed different HUVECs morphology which was spindle and cobblestone-shaped respectively after 72h of incubation. On the contrary, a monolayer of well-spread HUVECs formed on the Ar and N 2 plasma-treated OSTE-80 polymers. These variable morphologies observed can be ascribed to the adherence HUVECs on the different elastic moduli of these surfaces whereby further investigation might be needed. Overall, Ar and N 2 plasma treatment had successfully altered the surface properties of PUMA and OSTE-80 polymer by increasing its surface energy, hydrophilicity and chemical functionalities to create a biocompatible surface for HUVECs adhesion and proliferation. Copyright © 2017 Elsevier B.V. All rights reserved.

TOXICOLOGICAL HIGHLIGHT (REDOX REDUX: A CLOSER LOOK AT CONCEPTAL LOW MOLECULAR WEIGHT THIOLS)

EPA Science Inventory

Glutathione (GSH) is present as the most abundant low molecular weight thiol (LMWT) in virtually all mitochondria-bearing eucaryotic cells, often at millimolar concentrations (Meister, 1988). Functions of GSH include roles in DNA and protein synthesis, maintenance of cell membra...

Factors affecting the presence of dissolved glutathione in estuarine waters.

PubMed

Tang, Degui; Shafer, Martin M; Karner, Dawn A; Overdier, Joel; Armstrong, David E

2004-08-15

We investigated factors influencing the presence of the thiol glutathione (GSH) in estuarine waters. Our study addressed thiol phase-association, the biological release from algal cultures, and the role of copper in both thiol release and preservation. Our measurements in three diverse estuaries in the continental United States (San Diego Bay, Cape Fear Estuary, and Norfolk Estuary) show that dissolved GSH, present at sub-nanomolar levels, is preferentially partitioned into the ultra-filtrate fraction (<1 kDa) in comparison with dissolved organic carbon (DOC). Concentrations of GSH generally increased with increases in total copper (Cu)levels, although large variability was observed among estuaries. In 30-h exposure experiments, release of dissolved GSH from the diatom Thalassiosira weissflogii into organic ligand-free experimental media was a strong function of added Cu concentration. The released GSH increased from about 0.02 to 0.27 fmol/cell as Cu was increased from the background level (0.5 nM) to 310 nM in the modified Aquil media. However, excretion of GSH was lower (up to 0.13 fmol/cell) when cells were grown in surface waters of San Diego Bay, despite much higher total Cu concentrations. Experiments conducted in-situ in San Diego Bay water indicated that high concentrations of added Cu destabilized GSH, while both Mn(II) and natural colloids promoted GSH stability. In contrast, laboratory experiments in synthetic media indicated that moderate levels of added Cu enhanced GSH stability.

Poly(allyl methacrylate) functionalized hydroxyapatite nanocrystals via the combination of surface-initiated RAFT polymerization and thiol-ene protocol: a potential anticancer drug nanocarrier.

PubMed

Bach, Long Giang; Islam, Md Rafiqul; Vo, Thanh-Sang; Kim, Se-Kwon; Lim, Kwon Taek

2013-03-15

Hydroxyapatite nanocrystals (HAP NCs) were encapsulated by poly(allyl methacrylate) (PolyAMA) employing controlled surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization of allyl methacrylate to afford HAP-PolyAMA nanohybrids. The subsequent thiol-ene coupling of nanohybrids with 2-mercaptosuccinic acid resulted HAP-Poly(AMA-COOH) possessing multicarboxyl group. The formation of the nanohybrids was confirmed by FT-IR and EDS analyses. The TGA and FE-SEM investigation were further suggested the grafting of PolyAMA onto HAP NCs. The utility of the HAP-PolyAMA nanohybrid as drug carrier was also explored. The pendant carboxyl groups on the external layers of nanohybrids were conjugated with anticancer drug cisplatin to afford HAP-Poly(AMA-COOH)/Pt complex. The formation of the complex was confirmed by FT-IR, XPS, and FE-SEM. In vitro evaluation of the synthesized complex as nanomedicine revealed its potential chemotherapeutic efficacy against cancer cell lines. Copyright © 2012 Elsevier Inc. All rights reserved.

Development of multifunctional nanoparticles towards applications in non-invasive magnetic resonance imaging and axonal tracing.

PubMed

Du, Yan; Qin, Yubo; Li, Zizhen; Yang, Xiuying; Zhang, Jingchang; Westwick, Harrison; Tsai, Eve; Cao, Xudong

2017-12-01

A multifunctional nanobiomaterial has been developed by deliberately combining functions of superparamagnetism, fluorescence, and axonal tracing into one material. Superparamagnetic iron oxide nanoparticles were first synthesized and coated with a silica layer to prevent emission quenching through core-dye interactions; a fluorescent molecule, fluorescein isothiocyanate, was doped inside second layer of silica shell to improve photo-stability and to enable further thiol functionalization. Subsequently, biotinylated dextran amine, a sensitive axonal tracing reagent, was immobilized on the thiol-functionalized nanoparticle surfaces. The resulting nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, magnetic resonance imaging and fluorescence confocal microscopy. In vitro cell experiments using both undifferentiated and differentiated Neuro-2a cells showed that the cells were able to take up the nanoparticles intracellularly and that the nanoparticles showed good biocompatibilities. In summary, this new material demonstrated promising performances for both optical and magnetic resonance imaging modalities, suggesting its promising potentials in applications such as in non-invasive imaging, particularly in neuronal tracing.

Au-thiol interaction chemistry to influence the structural transformation of semiconductor nanocrystals and formation of giant nanostructures.

PubMed

Bose, Riya; Manna, Goutam; Pradhan, Narayan

2014-04-09

Giant nanostructures which are difficult to design by the classical growth process can be fabricated in a facilitated and well programmed surface ligand removal protocol employing the thiol-gold strong interaction chemistry. When thiol capped small ZnSe seed nanocrystals are treated with amine capped gold particles, gold snatches the thiol ligands from ZnSe and forces them to agglomerate leading to the giant crystalline ZnSe nanostructures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compact and highly stable quantum dots through optimized aqueous phase transfer

NASA Astrophysics Data System (ADS)

Tamang, Sudarsan; Beaune, Grégory; Poillot, Cathy; De Waard, Michel; Texier-Nogues, Isabelle; Reiss, Peter

2011-03-01

A large number of different approaches for the aqueous phase transfer of quantum dots have been proposed. Surface ligand exchange with small hydrophilic thiols, such as L-cysteine, yields the lowest particle hydrodynamic diameter. However, cysteine is prone to dimer formation, which limits colloidal stability. We demonstrate that precise pH control during aqueous phase transfer dramatically increases the colloidal stability of InP/ZnS quantum dots. Various bifunctional thiols have been applied. The formation of disulfides, strongly diminishing the fluorescence QY has been prevented through addition of appropriate reducing agents. Bright InP/ZnS quantum dots with a hydrodynamic diameter <10 nm and long-term stability have been obtained. Finally we present in vitro studies of the quantum dots functionalized with the cell-penetrating peptide maurocalcine.

Selenite induces posttranscriptional blockade of HLA-E expression and sensitizes tumor cells to CD94/NKG2A-positive NK cells.

PubMed

Enqvist, Monika; Nilsonne, Gustav; Hammarfjord, Oscar; Wallin, Robert P A; Björkström, Niklas K; Björnstedt, Mikael; Hjerpe, Anders; Ljunggren, Hans-Gustaf; Dobra, Katalin; Malmberg, Karl-Johan; Carlsten, Mattias

2011-10-01

CD94/NKG2A is an inhibitory receptor that controls the activity of a large proportion of human NK cells following interactions with the nonclassical HLA class Ib molecule HLA-E expressed on target cells. In this study, we show that selenite (SeO(3)(2-)), an inorganic selenium compound, induces an almost complete loss of cell surface expression of HLA-E on tumor cells of various origins. Selenite abrogated the HLA-E expression at a posttranscriptional level, since selenite exposure led to a dose-dependent decrease in cellular HLA-E protein expression whereas the mRNA levels remained intact. The loss of HLA-E expression following selenite treatment was associated with decreased levels of intracellular free thiols in the tumor cells, suggesting that the reduced HLA-E protein synthesis was caused by oxidative stress. Indeed, HLA-E expression and the level of free thiols remained intact following treatment with selenomethionine, a selenium compound that does not generate oxidative stress. Loss of HLA-E expression, but not of total HLA class I expression, on tumor cells resulted in increased susceptibility to CD94/NK group 2A-positive NK cells. Our results suggest that selenite may be used to potentiate the anti-tumor cytotoxicity in settings of NK cell-based immunotherapies.

Superhydrophobic and Slippery Lubricant-Infused Flexible Transparent Nanocellulose Films by Photoinduced Thiol-Ene Functionalization.

PubMed

Guo, Jiaqi; Fang, Wenwen; Welle, Alexander; Feng, Wenqian; Filpponen, Ilari; Rojas, Orlando J; Levkin, Pavel A

2016-12-14

Films comprising nanofibrillated cellulose (NFC) are suitable substrates for flexible devices in analytical, sensor, diagnostic, and display technologies. However, some major challenges in such developments include their high moisture sensitivity and the complexity of current methods available for functionalization and patterning. In this work, we present a facile process for tailoring the surface wettability and functionality of NFC films by a fast and versatile approach. First, the NFC films were coated with a layer of reactive nanoporous silicone nanofilament by polycondensation of trichlorovinylsilane (TCVS). The TCVS afforded reactive vinyl groups, thereby enabling simple UV-induced functionalization of NFC films with various thiol-containing molecules via the photo "click" thiol-ene reaction. Modification with perfluoroalkyl thiols resulted in robust superhydrophobic surfaces, which could then be further transformed into transparent slippery lubricant-infused NFC films that displayed repellency against both aqueous and organic liquids with surface tensions as low as 18 mN·m -1 . Finally, transparent and flexible NFC films incorporated hydrophilic micropatterns by modification with OH, NH 2 , or COOH surface groups, enabling space-resolved superhydrophobic-hydrophilic domains. Flexibility, transparency, patternability, and perfect superhydrophobicity of the produced nanocellulose substrates warrants their application in biosensing, display protection, and biomedical and diagnostics devices.

Metal Halide Solid-State Surface Treatment for High Efficiency PbS and PbSe QD Solar Cells

PubMed Central

Crisp, Ryan W.; Kroupa, Daniel M.; Marshall, Ashley R.; Miller, Elisa M.; Zhang, Jianbing; Beard, Matthew C.; Luther, Joseph M.

2015-01-01

We developed a layer-by-layer method of preparing PbE (E = S or Se) quantum dot (QD) solar cells using metal halide (PbI2, PbCl2, CdI2, or CdCl2) salts dissolved in dimethylformamide to displace oleate surface ligands and form conductive QD solids. The resulting QD solids have a significant reduction in the carbon content compared to films treated with thiols and organic halides. We find that the PbI2 treatment is the most successful in removing alkyl surface ligands and also replaces most surface bound Cl- with I-. The treatment protocol results in PbS QD films exhibiting a deeper work function and band positions than other ligand exchanges reported previously. The method developed here produces solar cells that perform well even at film thicknesses approaching a micron, indicating improved carrier transport in the QD films. We demonstrate QD solar cells based on PbI2 with power conversion efficiencies above 7%. PMID:25910183

Metal halide solid-state surface treatment for high efficiency PbS and PbSe QD solar cells.

PubMed

Crisp, Ryan W; Kroupa, Daniel M; Marshall, Ashley R; Miller, Elisa M; Zhang, Jianbing; Beard, Matthew C; Luther, Joseph M

2015-04-24

We developed a layer-by-layer method of preparing PbE (E = S or Se) quantum dot (QD) solar cells using metal halide (PbI2, PbCl2, CdI2, or CdCl2) salts dissolved in dimethylformamide to displace oleate surface ligands and form conductive QD solids. The resulting QD solids have a significant reduction in the carbon content compared to films treated with thiols and organic halides. We find that the PbI2 treatment is the most successful in removing alkyl surface ligands and also replaces most surface bound Cl(-) with I(-). The treatment protocol results in PbS QD films exhibiting a deeper work function and band positions than other ligand exchanges reported previously. The method developed here produces solar cells that perform well even at film thicknesses approaching a micron, indicating improved carrier transport in the QD films. We demonstrate QD solar cells based on PbI2 with power conversion efficiencies above 7%.

Metal Halide Solid-State Surface Treatment for High Efficiency PbS and PbSe QD Solar Cells

DOE PAGES

Crisp, R. W.; Kroupa, D. M.; Marshall, A. R.; ...

2015-04-24

We developed a layer-by-layer method of preparing PbE (E = S or Se) quantum dot (QD) solar cells using metal halide (PbI 2, PbCl 2, CdI 2, or CdCl 2) salts dissolved in dimethylformamide to displace oleate surface ligands and form conductive QD solids. The resulting QD solids have a significant reduction in the carbon content compared to films treated with thiols and organic halides. We find that the PbI 2 treatment is the most successful in removing alkyl surface ligands and also replaces most surface bound Cl- with I-. The treatment protocol results in PbS QD films exhibiting amore » deeper work function and band positions than other ligand exchanges reported previously. The method developed here produces solar cells that perform well even at film thicknesses approaching a micron, indicating improved carrier transport in the QD films. We demonstrate QD solar cells based on PbI 2 with power conversion efficiencies above 7%.« less

Patchy micelles based on coassembly of block copolymer chains and block copolymer brushes on silica particles.

PubMed

Zhu, Shuzhe; Li, Zhan-Wei; Zhao, Hanying

2015-04-14

Patchy particles are a type of colloidal particles with one or more well-defined patches on the surfaces. The patchy particles with multiple compositions and functionalities have found wide applications from the fundamental studies to practical uses. In this research patchy micelles with thiol groups in the patches were prepared based on coassembly of free block copolymer chains and block copolymer brushes on silica particles. Thiol-terminated and cyanoisopropyl-capped polystyrene-block-poly(N-isopropylacrylamide) block copolymers (PS-b-PNIPAM-SH and PS-b-PNIPAM-CIP) were synthesized by reversible addition-fragmentation chain transfer polymerization and chemical modifications. Pyridyl disulfide-functionalized silica particles (SiO2-SS-Py) were prepared by four-step surface chemical reactions. PS-b-PNIPAM brushes on silica particles were prepared by thiol-disulfide exchange reaction between PS-b-PNIPAM-SH and SiO2-SS-Py. Surface micelles on silica particles were prepared by coassembly of PS-b-PNIPAM-CIP and block copolymer brushes. Upon cleavage of the surface micelles from silica particles, patchy micelles with thiol groups in the patches were obtained. Dynamic light scattering, transmission electron microscopy, and zeta-potential measurements demonstrate the preparation of patchy micelles. Gold nanoparticles can be anchored onto the patchy micelles through S-Au bonds, and asymmetric hybrid structures are formed. The thiol groups can be oxidized to disulfides, which results in directional assembly of the patchy micelles. The self-assembly behavior of the patchy micelles was studied experimentally and by computer simulation.

Surface-modified gold nanorods for specific cell targeting

NASA Astrophysics Data System (ADS)

Wang, Chan-Ung; Arai, Yoshie; Kim, Insun; Jang, Wonhee; Lee, Seonghyun; Hafner, Jason H.; Jeoung, Eunhee; Jung, Deokho; Kwon, Youngeun

2012-05-01

Gold nanoparticles (GNPs) have unique properties that make them highly attractive materials for developing functional reagents for various biomedical applications including photothermal therapy, targeted drug delivery, and molecular imaging. For in vivo applications, GNPs need to be prepared with very little or negligible cytotoxicitiy. Most GNPs are, however, prepared using growth-directing surfactants such as cetyl trimethylammonium bromide (CTAB), which are known to have considerable cytotoxicity. In this paper, we describe an approach to remove CTAB to a non-toxic concentration. We optimized the conditions for surface modification with methoxypolyethylene glycol thiol (mPEG), which replaced CTAB and formed a protective layer on the surface of gold nanorods (GNRs). The cytotoxicities of pristine and surface-modified GNRs were measured in primary human umbilical vein endothelial cells and human cell lines derived from hepatic carcinoma cells, embryonic kidney cells, and thyroid papillary carcinoma cells. Cytotoxicity assays revealed that treating cells with GNRs did not significantly affect cell viability except for thyroid papillary carcinoma cells. Thyroid cancer cells were more susceptible to residual CTAB, so CTAB had to be further removed by dialysis in order to use GNRs for thyroid cell targeting. PEGylated GNRs are further modified to present monoclonal antibodies that recognize a specific surface marker, Na-I symporter, for thyroid cells. Antibody-conjugated GNRs specifically targeted human thyroid cells in vitro.

Thiol functionalized polymethacrylic acid-based hydrogel microparticles for oral insulin delivery.

PubMed

Sajeesh, S; Vauthier, C; Gueutin, C; Ponchel, G; Sharma, Chandra P

2010-08-01

In the present study thiol functionalized polymethacrylic acid-polyethylene glycol-chitosan (PCP)-based hydrogel microparticles were utilized to develop an oral insulin delivery system. Thiol modification was achieved by grafting cysteine to the activated surface carboxyl groups of PCP hydrogels (Cys-PCP). Swelling and insulin loading/release experiments were conducted on these particles. The ability of these particles to inhibit protease enzymes was evaluated under in vitro experimental conditions. Insulin transport experiments were performed on Caco-2 cell monolayers and excised intestinal tissue with an Ussing chamber set-up. Finally, the efficacy of insulin-loaded particles in reducing the blood glucose level in streptozotocin-induced diabetic rats was investigated. Thiolated hydrogel microparticles showed less swelling and had a lower insulin encapsulation efficiency as compared with unmodified PCP particles. PCP and Cys-PCP microparticles were able to inhibit protease enzymes under in vitro conditions. Thiolation was an effective strategy to improve insulin absorption across Caco-2 cell monolayers, however, the effect was reduced in the experiments using excised rat intestinal tissue. Nevertheless, functionalized microparticles were more effective in eliciting a pharmacological response in diabetic animal, as compared with unmodified PCP microparticles. From these studies thiolation of hydrogel microparticles seems to be a promising approach to improve oral delivery of proteins/peptides. Copyright 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A repeatable assembling and disassembling electrochemical aptamer cytosensor for ultrasensitive and highly selective detection of human liver cancer cells.

PubMed

Sun, Duanping; Lu, Jing; Chen, Zuanguang; Yu, Yanyan; Mo, Manni

2015-07-23

In this work, a repeatable assembling and disassembling electrochemical aptamer cytosensor was proposed for the sensitive detection of human liver hepatocellular carcinoma cells (HepG2) based on a dual recognition and signal amplification strategy. A high-affinity thiolated TLS11a aptamer, covalently attached to a gold electrode through Au-thiol interactions, was adopted to recognize and capture the target HepG2 cells. Meanwhile, the G-quadruplex/hemin/aptamer and horseradish peroxidase (HRP) modified gold nanoparticles (G-quadruplex/hemin/aptamer-AuNPs-HRP) nanoprobe was designed. It could be used for electrochemical cytosensing with specific recognition and enzymatic signal amplification of HRP and G-quadruplex/hemin HRP-mimicking DNAzyme. With the nanoprobes as recognizing probes, the HepG2 cancer cells were captured to fabricate an aptamer-cell-nanoprobes sandwich-like superstructure on a gold electrode surface. The proposed electrochemical cytosensor delivered a wide detection range from 1×10(2) to 1×10(7) cells mL(-1) and high sensitivity with a low detection limit of 30 cells mL(-1). Furthermore, after the electrochemical detection, the activation potential of -0.9 to -1.7V was performed to break Au-thiol bond and regenerate a bare gold electrode surface, while maintaining the good characteristic of being used repeatedly. The changes of gold electrode behavior after assembling and desorption processes were investigated by electrochemical impedance spectroscopy and cyclic voltammetry techniques. These results indicate that the cytosensor has great potential in disease diagnostic of cancers and opens new insight into the reusable gold electrode with repeatable assembling and disassembling in the electrochemical sensing. Copyright © 2015 Elsevier B.V. All rights reserved.

Superhydrophobic hybrid inorganic-organic thiol-ene surfaces fabricated via spray-deposition and photopolymerization.

PubMed

Sparks, Bradley J; Hoff, Ethan F T; Xiong, Li; Goetz, James T; Patton, Derek L

2013-03-13

We report a simple and versatile method for the fabrication of superhydrophobic inorganic-organic thiol-ene coatings via sequential spray-deposition and photopolymerization under ambient conditions. The coatings are obtained by spray-deposition of UV-curable hybrid inorganic-organic thiol-ene resins consisting of pentaerythritol tetra(3-mercaptopropionate) (PETMP), triallyl isocyanurate (TTT), 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (TMTVSi), and hydrophobic fumed silica nanoparticles. The spray-deposition process and nanoparticle agglomeration/dispersion provide surfaces with hierarchical morphologies exhibiting both micro- and nanoscale roughness. The wetting behavior, dependent on the concentration of TMTVSi and hydrophobic silica nanoparticles, can be varied over a broad range to ultimately provide coatings with high static water contact angles (>150°), low contact angle hysteresis, and low roll off angles (<5°). The cross-linked thiol-ene coatings are solvent resistant, stable at low and high pH, and maintain superhydrophobic wetting behavior after extended exposure to elevated temperatures. We demonstrate the versatility of the spray-deposition and UV-cure process on a variety of substrate surfaces including glass, paper, stone, and cotton fabric.

Endothelin-1 receptor antagonists regulate cell surface-associated protein disulfide isomerase in sickle cell disease

PubMed Central

Prado, Gregory N.; Romero, Jose R.; Rivera, Alicia

2013-01-01

Increased endothelin-1 (ET-1) levels, disordered thiol protein status, and erythrocyte hydration status play important roles in sickle cell disease (SCD) through unresolved mechanisms. Protein disulfide isomerase (PDI) is an oxidoreductase that mediates thiol/disulfide interchange reactions. We provide evidence that PDI is present in human and mouse erythrocyte membranes and that selective blockade with monoclonal antibodies against PDI leads to reduced Gardos channel activity (1.6±0.03 to 0.56±0.02 mmol·1013 cell−1·min−1, P<0.001) and density of sickle erythrocytes (D50: 1.115±0.001 to 1.104±0.001 g/ml, P=0.012) with an IC50 of 4 ng/ml. We observed that erythrocyte associated-PDI activity was increased in the presence of ET-1 (3.1±0.2 to 5.6±0.4%, P<0.0001) through a mechanism that includes casein kinase II. Consistent with these results, in vivo treatment of BERK sickle transgenic mice with ET-1 receptor antagonists lowered circulating and erythrocyte associated-PDI activity (7.1±0.3 to 5.2±0.2%, P<0.0001) while improving hematological parameters and Gardos channel activity. Thus, our results suggest that PDI is a novel target in SCD that regulates erythrocyte volume and oxidative stress and may contribute to cellular adhesion and endothelial activation leading to vasoocclusion as observed in SCD.—Prado, G. N., Romero, J. R., Rivera, A. Endothelin-1 receptor antagonists regulate cell surface-associated protein disulfide isomerase in sickle cell disease. PMID:23913858

Thiol redox transitions in cell signaling: a lesson from N-acetylcysteine.

PubMed

Parasassi, Tiziana; Brunelli, Roberto; Costa, Graziella; De Spirito, Marco; Krasnowska, Ewa; Lundeberg, Thomas; Pittaluga, Eugenia; Ursini, Fulvio

2010-06-29

The functional status of cells is under the control of external stimuli affecting the function of critical proteins and eventually gene expression. Signal sensing and transduction by messengers to specific effectors operate by post-translational modification of proteins, among which thiol redox switches play a fundamental role that is just beginning to be understood. The maintenance of the redox status is, indeed, crucial for cellular homeostasis and its dysregulation towards a more oxidized intracellular environment is associated with aberrant proliferation, ultimately related to diseases such as cancer, cardiovascular disease, and diabetes. Redox transitions occur in sensitive cysteine residues of regulatory proteins relevant to signaling, their evolution to metastable disulfides accounting for the functional redox switch. N-acetylcysteine (NAC) is a thiol-containing compound that is able to interfere with redox transitions of thiols and, thus, in principle, able to modulate redox signaling. We here review the redox chemistry of NAC, then screen possible mechanisms to explain the effects observed in NAC-treated normal and cancer cells; such effects involve a modification of global gene expression, thus of functions and morphology, with a leitmotif of a switch from proliferation to terminal differentiation. The regulation of thiol redox transitions in cell signaling is, therefore, proposed as a new tool, holding promise not only for a deeper explanation of mechanisms, but indeed for innovative pharmacological interventions.

One-step fabrication of PEGylated fluorescent nanodiamonds through the thiol-ene click reaction and their potential for biological imaging

NASA Astrophysics Data System (ADS)

Huang, Hongye; Liu, Meiying; Tuo, Xun; Chen, Junyu; Mao, Liucheng; Wen, Yuanqing; Tian, Jianwen; Zhou, Naigen; Zhang, Xiaoyong; Wei, Yen

2018-05-01

Over the past years, fluorescent carbon nanoparticles have got growing interest for biological imaging. Fluorescent nanodiamonds (FNDs) are novel fluorescent carbon nanoparticles with multitudinous useful properties, including remarkable fluorescence properties, extremely low toxicity and high refractive index. However, facile preparation of FNDs with designable properties and functions from non-fluorescent detonation nanodiamonds (DNDs) has demonstrated to be challengeable. In this work, we reported for the first time that preparation of Polyethylene glycol (PEG) functionalized FNDs through a one-step thiol-ene click reaction using thiol containing PEG (PEG-SH) as the coating agent. Based on the characterization results, we demonstrated that PEG-SH could be efficiently introduced on DNDs to obtain FNDs through the thiol-ene click chemistry. The resultant FND-PEG composites showed high water dispersibility, strong fluorescence and low cytotoxicity. Moreover, FND-PEG composites could be internalized by cells and displayed good cell dyeing performance. All of these features implied that FND-PEG composites are of great potential for biological imaging. Taken together, a facile one-step strategy based on the one-step thiol-ene click reaction has been developed for efficient preparation of FND-PEG composites from non-fluorescent DNDs. The strategy should be also useful for fabrication of many other functional FNDs via using different thiol containing compounds for the universality of thiol-ene click reaction.

Evolution of thiol protective systems in prokaryotes

NASA Technical Reports Server (NTRS)

Fahey, R. C.; Newton, G. L.

1986-01-01

Biological thiols are essential elements in most aspects of cell function but undergo rapid oxidation to disulfides in the presence of oxygen. The evolution of systems to protect against such oxygen toxicity was essential to the emergence of aerobic life. The protection system used by eukaryotes is based upon glutathione (GSH) and GSH-dependent enzymes but many bacteria lack GSH and apparently use other mechanisms. The objective of this research is to elaborate the thiol protective mechanisms employed by prokaryotes of widely divergent evolutionary origin and to understand why GSH became the central thiol employed in essentially all higher organisms. Thiol-selective fluorescent labeling and HPLC analysis has been used to determine key monothiol components.

Facile fabrication of redox-responsive thiol-containing drug delivery system via RAFT polymerization.

PubMed

Zhuang, Yuanyuan; Su, Yue; Peng, Yu; Wang, Dali; Deng, Hongping; Xi, Xiaodong; Zhu, Xinyuan; Lu, Yunfeng

2014-04-14

A novel kind of redox-responsive polymeric drug delivery system has been designed and prepared successfully through the coupling of the multithiol branched polymers and thiol-containing drugs. The branched poly((S-(4-vinyl) benzyl S'-propyltrithiocarbonate)-co-(poly(ethylene glycol) methacrylate)) (poly(VBPT-co-PEGMA)) was synthesized by one-pot reaction via reversible addition-fragmentation chain transfer (RAFT) copolymerization. Subsequently, the hydrophobic thiol-containing anticancer drug 6-mercaptopurine (MP) was conjugated to poly(VBPT-co-PEGMA) by thiol-disulfide exchange reaction, resulting in the formation of poly(VBPT-co-PEGMA)-S-S-MP conjugate. Due to its amphiphilicity, poly(VBPT-co-PEGMA)-S-S-MP conjugate self-assembled into amphiphilic micelles in aqueous solution. Under a reductive environment, the disassembly of polymeric micelles resulted in the MP release. Flow cytometry and confocal laser scanning microscopy (CLSM) measurements demonstrated that the poly(VBPT-co-PEGMA)-S-S-MP micelles could be taken up by Raji cells (a Burkitt lymphoma cell line). The viability of the Raji cells incubated with the glutathione (GSH) mediated poly(VBPT-co-PEGMA)-S-S-MP micelles was investigated by Cell Counting Kit-8 (CCK-8) assay. The experimental results showed that the viability of the glutathione monoester (GSH-OEt) pretreated cells was lower than that without pretreatment, while the viability of the buthionine sulfoximine (BSO) pretreated cells was higher than that without pretreatment. The poly(VBPT-co-PEGMA)-S-S-MP micelles could induce the apoptosis of Raji cells, and the apoptosis behavior was dose-dependent. This redox-responsive polymer-drug conjugate provides a promising platform for the delivery of thiol-containing biological molecules.

Self-Assembled N-Heterocyclic Carbene-Based Carboxymethylated Dextran Monolayers on Gold as a Tunable Platform for Designing Affinity-Capture Biosensor Surfaces.

PubMed

Li, Zhijun; Munro, Kim; Narouz, Mina R; Lau, Andrew; Hao, Hongxia; Crudden, Cathleen M; Horton, J Hugh

2018-05-30

Sensor surfaces play a predominant role in the development of optical biosensor technologies for the analysis of biomolecular interactions. Thiol-based self-assembled monolayers (SAMs) on gold have been widely used as linker layers for sensor surfaces. However, the degradation of the thiol-gold bond can limit the performance and durability of such surfaces, directly impacting their performance and cost-effectiveness. To this end, a new family of materials based on N-heterocyclic carbenes (NHCs) has emerged as an alternative for surface modification, capable of self-assembling onto a gold surface with higher affinity and superior stability as compared to the thiol-based systems. Here we demonstrate three applications of NHC SAMs supporting a dextran layer as a tunable platform for developing various affinity-capture biosensor surfaces. We describe the development and testing of NHC-based dextran biosensor surfaces modified with each of streptavidin, nitrilotriacetic acid, and recombinant Protein A. These affinity-capture sensor surfaces enable oriented binding of ligands for optimal performance in biomolecular assays. Together, the intrinsic high stability and flexible design of the NHC biosensing platforms show great promise and open up exciting possibilities for future biosensing applications.

Attaching Thiolated Superconductor Grains on Gold Surfaces for Nanoelectronics Applications

NASA Astrophysics Data System (ADS)

De Los Santos Valladares, Luis; Bustamante Dominguez, Angel; Llandro, Justin; Suzuki, Seiichi; Mitrelias, Thanos; Bellido Quispe, Richard; Barnes, Crispin H. W.; Majima, Yutaka

2010-09-01

We report that the high critical temperature superconductor (HTCS) LaCaBaCu3O7 in the form of nanograins can be linked to Au(111) surfaces through self assembled monolayers (SAMs) of HS-C8H16-HS [octane (di)thiol]. We show that La1113 particles (100 nm mean diameter) can be functionalized by octane (di)thiol without affecting their superconducting critical temperature (TC=80 K). X-ray photoemission spectroscopy (XPS) analysis reveals that the thiol functional heads link the superconducting grain surfaces creating sulfonates and we deduce that bonding between the S atoms and Cu(1) atoms of the La1113 structure would be formed. We suggest a design for a superconducting transistor fabricated by immobilized La1113 nanograins in between two gold electrodes which could be controlled by an external magnetic field gate.

N-Acetylcysteine Amide Protects Against Oxidative Stress–Induced Microparticle Release From Human Retinal Pigment Epithelial Cells

PubMed Central

Carver, Kyle A.; Yang, Dongli

2016-01-01

Purpose Oxidative stress is a major factor involved in retinal pigment epithelium (RPE) apoptosis that underlies AMD. Drusen, extracellular lipid- and protein-containing deposits, are strongly associated with the development of AMD. Cell-derived microparticles (MPs) are small membrane-bound vesicles shed from cells. The purpose of this study was to determine if oxidative stress drives MP release from RPE cells, to assess whether these MPs carry membrane complement regulatory proteins (mCRPs: CD46, CD55, and CD59), and to evaluate the effects of a thiol antioxidant on oxidative stress–induced MP release. Methods Retinal pigment epithelium cells isolated from human donor eyes were cultured and treated with hydrogen peroxide (H2O2) to induce oxidative stress. Isolated MPs were fixed for transmission electron microscopy or processed for component analysis by flow cytometry, Western blot analysis, and confocal microscopy. Results Transmission electron microscopy showed that MPs ranged in diameter from 100 to 1000 nm. H2O2 treatment led to time- and dose-dependent elevations in MPs with externalized phosphatidylserine and phosphatidylethanolamine, known markers of MPs. These increases were strongly correlated to RPE apoptosis. Oxidative stress significantly increased the release of mCRP-positive MPs, which were prevented by a thiol antioxidant, N-acetylcysteine amide (NACA). Conclusions This is the first evidence that oxidative stress induces cultured human RPE cells to release MPs that carry mCRPs on their surface. The levels of released MPs are strongly correlated with RPE apoptosis. N-acetylcysteine amide prevents oxidative stress–induced effects. Our findings indicate that oxidative stress reduces mCRPs on the RPE surface through releasing MPs. PMID:26842754

Are free radicals involved in thiol-based redox signaling?

PubMed

Winterbourn, Christine C

2015-03-01

Cells respond to many stimuli by transmitting signals through redox-regulated pathways. It is generally accepted that in many instances signal transduction is via reversible oxidation of thiol proteins, although there is uncertainty about the specific redox transformations involved. The prevailing view is that thiol oxidation occurs by a two electron mechanism, most commonly involving hydrogen peroxide. Free radicals, on the other hand, are considered as damaging species and not generally regarded as important in cell signaling. This paper examines whether it is justified to dismiss radicals or whether they could have a signaling role. Although there is no direct evidence that radicals are involved in transmitting thiol-based redox signals, evidence is presented that they are generated in cells when these signaling pathways are activated. Radicals produce the same thiol oxidation products as two electron oxidants, although by a different mechanism, and at this point radical-mediated pathways should not be dismissed. There are unresolved issues about how radical mechanisms could achieve sufficient selectivity, but this could be possible through colocalization of radical-generating and signal-transducing proteins. Colocalization is also likely to be important for nonradical signaling mechanisms and identification of such associations should be a priority for advancing the field. Copyright © 2014 Elsevier Inc. All rights reserved.

Simultaneous LC/MS/MS determination of thiols and disulfides in urine samples based on differential labeling with ferrocene-based maleimides.

PubMed

Seiwert, Bettina; Karst, Uwe

2007-09-15

A method for the simultaneous determination of a series of thiols and disulfides in urine samples has been developed based on the sequential labeling of free and bound thiol functionalities with two ferrocene-based maleimide reagents. The sample is first exposed to N-(2-ferroceneethyl)maleimide, thus leading to the derivatization of free thiol groups in the sample. After quantitative reaction and subsequent reduction of the disulfide-bound thiols by tris(2-carboxyethyl)phosphine, the newly formed thiol functionalities are reacted with ferrocenecarboxylic acid-(2-maleimidoyl)ethylamide. The reaction products are determined by LC/MS/MS in the multiple reaction mode, and precursor ion scan as well as neutral loss scan is applied to detect unknown further thiols. The method was successfully applied to the analysis of free and disulfide-bound thiols in urine samples. Limits of detection are 30 to 110 nM, and the linear range comprises two decades of concentration, thus covering the relevant concentration range of thiols in urine samples. The thiol and disulfide concentrations were referred to the creatinine content to compensate for different sample volumes. As some calibration standards for the disulfides are not commercially available, they were synthesized in an electrochemical flow-through cell. This allowed the synthesis of hetero- and homodimeric disulfides.

Influence of amine and thiol modifications at the 3' ends of single stranded DNA molecules on their adsorption on gold surface and the efficiency of their hybridization.

PubMed

Jaworska, Aleksandra; Jablonska, Anna; Wilanowski, Tomasz; Palys, Barbara; Sek, Slawomir; Kudelski, Andrzej

2018-05-24

Adsorption of molecules of DNA (deoxyribonucleic acid) or modified DNA on gold surfaces is often the first step in construction of many various biosensors, including biosensors for detection of DNA with a particular sequence. In this work we study the influence of amine and thiol modifications at the 3' ends of single stranded DNA (ssDNA) molecules on their adsorption on the surface of gold substrates and on the efficiency of hybridization of immobilized DNA with the complementary single stranded DNA. The characterization of formed layers has been carried out using infrared spectroscopy and atomic force microscopy. As model single stranded DNA we used DNA containing 20 adenine bases, whereas the complementary DNA contained 20 thymine bases. We found that the bands in polarization modulation-infrared reflection-adsorption spectroscopy (PM-IRRAS) spectra of layers formed from thiol-modified DNA are significantly narrower and sharper, indicating their higher regularity in the orientation of DNA on gold surface when using thiol linker. Also, hybridization of the layer of thiol-modified DNA containing 20 adenine bases with the respective DNA containing thymine bases leads to formation of much more organized structures than in the case of unmodified DNA or DNA with the amine linker. We conclude that the thiol-modified ssDNA is more promising for the preparation of biosensors, in comparison with the amine-modified or unmodified ssDNA. We have also found that the above-mentioned modifications at the 3' end of ssDNA significantly influence the IR spectrum (and hence the structure) of polycrystalline films formed from such compounds, even though adsorbed fragments contain less than 5% of the DNA chain. This effect should be taken into account when comparing IR spectra of various polycrystalline films formed from modified and unmodified DNA. Copyright © 2018. Published by Elsevier B.V.

Surface charge fine tuning of reversed-phase/weak anion-exchange type mixed-mode stationary phases for milder elution conditions.

PubMed

Zimmermann, Aleksandra; Horak, Jeannie; Sánchez-Muñoz, Orlando L; Lämmerhofer, Michael

2015-08-28

A series of new mixed-mode reversed-phase/weak anion-exchange (RP/WAX) phases have been synthesized by immobilization of N-undecenyl-3-α-aminotropane onto thiol-modified silica gel by thiol-ene click chemistry and subsequent introduction of acidic thiol-endcapping functionalities of different type and surface densities. Click chemistry allowed to adjust a controlled surface concentration of the RP/WAX ligand in such a way that a sufficient quantity of residual thiols remained unmodified which have been capped by thiol click with either 3-butenoic acid or allylsulfonic acid as co-ligands. In another embodiment, performic acid oxidation of N-undecenyl-3-α-aminotropane-derivatized thiol-modified silica gave a RP/WAX phase with high density of sulfonic acid end-capping groups. ζ-Potential determinations confirmed the fine-tuned pI of these mixed-mode stationary phases which was shifted from 9.5 to 8.2, 7.8, and 6.5 with 3-butenoic acid and allylsulfonic acid end-capping as well as performic acid oxidation. For acidic solutes, the co-ionic endcapping leads to strongly reduced retention times and clearly allowed elution of these analytes under lower ionic strength thus milder elution conditions. In spite of the acidic endcapping, the new mixed-mode phases maintained their hydrophobic and anion-exchange selectivity as well as their multimodal nature featuring RP and HILIC elution domains at acetonitrile percentages below and above 50%, respectively. Column classification by principal component analysis of an extended retention map in comparison to a set of polar commercial and in-house synthesized stationary phases confirmed complementarity of the new mixed-mode phases with respect to HILIC, polar RP, amino and commercial mixed-mode phases. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly Reactive Thiol-Norbornene Photo-Click Hydrogels: Toward Improved Processability.

PubMed

Van Hoorick, Jasper; Gruber, Peter; Markovic, Marica; Rollot, Mélanie; Graulus, Geert-Jan; Vagenende, Maxime; Tromayer, Maximilian; Van Erps, Jürgen; Thienpont, Hugo; Martins, José C; Baudis, Stefan; Ovsianikov, Aleksandr; Dubruel, Peter; Van Vlierberghe, Sandra

2018-06-10

In the present work, gelatin type B is modified with highly reactive norbornene functionalities (Gel-NB) following a one-pot synthesis approach to enable subsequent thiol-ene photo-click crosslinking. The modification strategy displays close control over the amount of introduced functionalities. Additionally, Gel-NB exhibits considerably improved processing capabilities in terms of two-photon polymerization when benchmarked to earlier-reported crosslinkable gelatin derivatives (e.g., gelatin-methacrylamide (Gel-MOD) and gelatin-methacrylamide-aminoethylmethacrylate (Gel-MOD-AEMA)). The improvement is especially apparent in terms of minimally required laser power (20 mW vs ≥60 mW (Gel-MOD) vs ≥40 mW (Gel-MOD-AEMA) at 100 mm s -1 scan speed) and processable concentration range (≥5 w/v% vs ≥10 w/v% (Gel-MOD/Gel-MOD-AEMA)). Furthermore, the proposed functionalization scheme maintains the excellent biocompatibility and cell interactivity of gelatin. Additionally, the norbornene functionalities have potential for straightforward postprocessing "thiol-ene" surface grafting of active molecules. As a consequence, a very promising material toward tissue engineering applications and more specifically, biofabrication, is presented. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Acid-Activatable Michael-Type Fluorescent Probes for Thiols and for Labeling Lysosomes in Live Cells.

PubMed

Dai, Chun-Guang; Du, Xiao-Jiao; Song, Qin-Hua

2015-12-18

A Michael addition is usually taken as a base-catalyzed reaction. Most fluorescent probes have been designed to detect thiols in slightly alkaline solutions (pH 7-9). The sensing reactions of almost all Michael-type fluorescent probes for thiols are faster in a high pH solution than in a low pH solution. In this work, we synthesized a series of 7-substituted 2-(quinolin-2-ylmethylene)malonic acids (QMAs, substituents: NEt2, OH, H, Cl, or NO2) and their ethyl esters (QMEs) as Michael-type fluorescent probes for thiols. The sensing reactions of QMAs and QMEs occur in distinct pH ranges, pH < 7 for QMAs and pH > 7 for QMEs. On the basis of experimental and theoretic studies, we have clarified the distinct pH effects on the sensing reactivity between QMAs and QMEs and demonstrated that two QMAs (NEt2, OH) are highly sensitive and selective fluorescent probes for thiols in acidic solutions (pH < 7) and promising dyes that can label lysosomes in live cells.

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Bhoopesh; Shoenfelt, Elizabeth; Yu, Qiang

We have examined the speciation of Hg(II) complexed with intact cell suspensions (1013 cells L- 1) of Bacillus subtilis, a common gram-positive soil bacterium, Shewanella oneidensis MR-1, a facultative gram-negative aquatic organism, and Geobacter sulfurreducens, a gram-negative anaerobic bacterium capable of Hg-methylation at Hg(II) loadings spanning four orders of magnitude (120 nM to 350 μM) at pH 5.5 (± 0.2). The coordination environments of Hg on bacterial cells were analyzed using synchrotron based X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Hg LIII edge. The abundance of thiols on intact cells wasmore » determined by a fluorescence-spectroscopy based method using a soluble bromobimane, monobromo(trimethylammonio)bimane (qBBr) to block thiol sites, and potentiometric titrations of biomass with and without qBBr treatment. The chemical forms of S on intact bacterial cells were determined using S k-edge XANES spectroscopy.« less

Conserved Cysteine Residues Provide a Protein-Protein Interaction Surface in Dual Oxidase (DUOX) Proteins*

PubMed Central

Meitzler, Jennifer L.; Hinde, Sara; Bánfi, Botond; Nauseef, William M.; Ortiz de Montellano, Paul R.

2013-01-01

Intramolecular disulfide bond formation is promoted in oxidizing extracellular and endoplasmic reticulum compartments and often contributes to protein stability and function. DUOX1 and DUOX2 are distinguished from other members of the NOX protein family by the presence of a unique extracellular N-terminal region. These peroxidase-like domains lack the conserved cysteines that confer structural stability to mammalian peroxidases. Sequence-based structure predictions suggest that the thiol groups present are solvent-exposed on a single protein surface and are too distant to support intramolecular disulfide bond formation. To investigate the role of these thiol residues, we introduced four individual cysteine to glycine mutations in the peroxidase-like domains of both human DUOXs and purified the recombinant proteins. The mutations caused little change in the stabilities of the monomeric proteins, supporting the hypothesis that the thiol residues are solvent-exposed and not involved in disulfide bonds that are critical for structural integrity. However, the ability of the isolated hDUOX1 peroxidase-like domain to dimerize was altered, suggesting a role for these cysteines in protein-protein interactions that could facilitate homodimerization of the peroxidase-like domain or, in the full-length protein, heterodimeric interactions with a maturation protein. When full-length hDUOX1 was expressed in HEK293 cells, the mutations resulted in decreased H2O2 production that correlated with a decreased amount of the enzyme localized to the membrane surface rather than with a loss of activity or with a failure to synthesize the mutant proteins. These results support a role for the cysteine residues in intermolecular disulfide bond formation with the DUOX maturation factor DUOXA1. PMID:23362256

Investigation of a thiolated polymer in gene delivery

NASA Astrophysics Data System (ADS)

Bacalocostantis, Irene

Thiol-containing bioreducible polymers show significant potential as delivery vectors in gene therapy, a rapidly growing field which seeks to treat genetic-based disorders by delivering functional synthetic genes to diseased cells. Studies have shown that thiolated polymers exhibit improved biodegradability and prolonged in vivo circulation times over non-thiolated polymers. However, the extent to which thiol concentrations impact the carrier's delivery potential has not been well explored. The aim of this dissertation is to investigate how relative concentrations of free thiols and disulfide crosslinks impact a polymeric carriers delivery performance with respect to DNA packaging, complex stability, cargo protection, gene release, internalization efficiency and cytotoxicity. To accomplish this goal, several fluorescent polymers containing varying concentrations of thiol groups were synthesized by conjugating thiol-pendant chains onto the primary amines of cationic poly(allylamine). In vitro delivery assays and characterization techniques were employed to assess the effect of thiols in gene delivery.

Mucoadhesive nanoparticles made of thiolated quaternary chitosan crosslinked with hyaluronan.

PubMed

Zambito, Ylenia; Felice, Francesca; Fabiano, Angela; Di Stefano, Rossella; Di Colo, Giacomo

2013-01-30

Mucoadhesive polymeric nanoparticles intended for drug transport across the gastrointestinal mucosa were prepared from quaternary ammonium-chitosan conjugates synthesised from reduced-MW chitosan (32 kDa). Conjugates contained pendant moieties of 2-4 adjacent diethyl-dimethylene-ammonium groups substituted on repeating units (26-55%). Conjugates were thiolated via amide bonds with thioglycolic acid to yield products with thiol content in the 35-87 μmol/g range. Nanoparticles with mean size in the 270-370 nm range and positive zeta-potential (+3.7 to +12.5 mV) resulted from ionotropic gelation of the thiolated conjugates with de-polymerised hyaluronic acid (470 kDa). The nanoparticles were fairly stable in size and thiol content and showed a significant mucoadhesivity, matching and even exceeding that of the constituent polymers. Nanoparticles were internalised by endothelial progenitor cells in direct relation to their surface charge intensity. Nanoparticle uptake significantly improved cell viability and resistance to oxidation. The lyophilised nanoparticles were re-dispersible and could make a manageable formulation for oral use. Copyright © 2012 Elsevier Ltd. All rights reserved.

Selective chromogenic detection of thiol-containing biomolecules using carbonaceous nanospheres loaded with silver nanoparticles as carrier.

PubMed

Hu, Bo; Zhao, Yang; Zhu, Hai-Zhou; Yu, Shu-Hong

2011-04-26

Thiol-containing biomolecules show strong affinity with noble metal nanostructures and could not only stably protect them but also control the self-assembly process of these special nanostructures. A highly selective and sensitive chromogenic detection method has been designed for the low and high molecular weight thiol-containing biomolecules, including cysteine, glutathione, dithiothreitol, and bovine serum albumin, using a new type of carbonaceous nanospheres loaded with silver nanoparticles (Ag NPs) as carrier. This strategy relies upon the place-exchange process between the reporter dyes on the surface of Ag NPs and the thiol groups of thiol-containing biomolecules. The concentration of biomolecules can be determined by monitoring with the fluorescence intensity of reporter dyes dispersed in solution. This new chromogenic assay method could selectively detect these biomolecules in the presence of various other amino acids and monosaccharides and even sensitively detect the thiol-containing biomolecules with different molecular weight, even including proteins.

Monoclonal antibody to a cancer-specific and drug-responsive hydroquinone (NADH) oxidase from the sera of cancer patients

NASA Technical Reports Server (NTRS)

Cho, NaMi; Chueh, Pin-Ju; Kim, Chinpal; Caldwell, Sara; Morre, Dorothy M.; Morre, D. James

2002-01-01

Monoclonal antibodies were generated in mice to a 34-kDa circulating form of a drug-responsive hydroquinone (NADH) oxidase with a protein disulfide-thiol interchange activity specific to the surface of cancer cells and the sera of cancer patients. Screening used Western blots with purified 34-kDa tNOX from HeLa cells and the sera of cancer patients. Epitopes were sought that inhibited the drug-responsive oxidation of NADH with the sera of cancer patients, but which had no effect on NADH oxidation with the sera of healthy volunteers. Two such antisera were generated. One, designated monoclonal antibody (mAb) 12.1, was characterized extensively. The NADH oxidase activity inhibited by mAb 12.1 also was inhibited by the quinone site inhibitor capsaicin (8-methyl- N-vanillyl-6-noneamide). The inhibition was competitive for the drug-responsive protein disulfide-thiol interchange activity assayed either by restoration of activity to scrambled RNase or by cleavage of a dithiodipyridine substrate, and was uncompetitive for NADH oxidation. Both the mAb 12.1 and the postimmune antisera immunoprecipitated drug-responsive NOX activity and identified the same 34-kDa tNOX protein in the sera of cancer patients that was absent from sera of healthy volunteers, and was utilized as immunogen. Preimmune sera from the same mouse as the postimmune antisera was without effect. Both mouse ascites containing mAb 12.1 and postimmune sera (but not preimmune sera) slowed the growth of human cancer cell lines in culture, but did not affect the growth of non-cancerous cell lines. Immunocytochemical and histochemical findings showed that mAb 12.1 reacted with the surface membranes of human carcinoma cells and tissues.

A Multifunctional Surface That Simultaneously Balances Hydrophilic Enzyme Catalysis and Hydrophobic Water Repellency.

PubMed

Lawton, Timothy J; Uzarski, Joshua R; Filocamo, Shaun F

2016-08-16

The compatibility of multiple functions at a single interface is difficult to achieve, but is even more challenging when the functions directly counteract one another. This study provides insight into the creation of a simultaneously multifunctional surface formed by balancing two orthogonal functions; water repellency and enzyme catalysis. A partially fluorinated thiol is used to impart bulk hydrophobicity on the surface, and an N-hydroxysuccinimide ester-terminated thiol provides a specific anchoring sites for the covalent enzyme attachment. Different ratios of the two thiols are mixed together to form amphiphilic self-assembled monolayers, which are characterized with polarization-modulation infrared reflection-absorption spectroscopy and contact angle goniometry. The enzyme activity is measured by a fluorescence assay. With the results collected here, specific surface compositions are identified at which the orthogonal functions of water repellency and enzyme catalysis are balanced and exist simultaneously. An understanding of how to effectively balance orthogonal functions at surfaces can be extended to a number of higher-scale applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functionalization of gold and graphene electrodes by p-maleimido-phenyl towards thiol-sensing systems investigated by EQCM and IR ellipsometric spectroscopy

NASA Astrophysics Data System (ADS)

Neubert, Tilmann J.; Rösicke, Felix; Sun, Guoguang; Janietz, Silvia; Gluba, Marc A.; Hinrichs, Karsten; Nickel, Norbert H.; Rappich, Jörg

2017-11-01

Electrografting of gold and graphene surfaces by functional p-(N-maleimido)phenyl groups was performed by reduction of p-(N-maleimido)phenyldiazonium tetrafluoroborate. The reduction was carried out using cyclic voltammetry coupled with micro-gravimetric measurements by means of electrochemical quartz crystal microbalance (EQCM). The overall deposited mass on gold was higher than on graphene. However, the Faradaic efficiency was lower on Au (14%) compared to graphene (22%) after the first potential scan. Subsequently, the maleimide functional groups have been tested for immobilization of terminal thiols using (4-nitrobenzyl)mercaptan for the functionalized graphene surface and a cysteine-modified peptide for the functionalized gold surface. The functionalization by p-(N-maleimido)phenyl groups and the following thiol coupling of the particular surface was proven by infrared spectroscopic ellipsometry (IRSE). In addition, the interaction of the tetrabutylammonium and tetrafluoroborate ions present in the electrolyte with the Au and graphene electrodes was investigated by EQCM and revealed less electrostatic interaction of graphene with these ions in solution compared to the metal (Au) surface.

Interfacial preparation and optical transmission surface plasmon resonance of Janus metamaterials membrane

NASA Astrophysics Data System (ADS)

Du, Yixuan; Zhang, Xiaowei; Li, Yunbo

2018-01-01

Janus metamaterials membrane had been fabricated using self-assembly strategy at the oil/water interface with thiol-terminated polymers. Janus metamaterials membrane exhibits a characteristic surface plasmon absorption band, in which the peak position is sensitive to the addition of polymer. The optical transmission surface plasmon resonance (T-SPR) peak has a blue shift at the visible region with addition of thiol-terminated polystyrene (PS-SH). With thiol-terminated poly (ethylene glycol) (PEG-SH) attachment onto the surface side of gold nanoparticles (AuNPs), the T-SPR band has a successive blue shift. One surprising thing is that it has a flat terrace on T-SPR band from 580 to 740 nm. In addition, The T-SPR of Janus metamaterials membrane dramatically changed with the addition PS-SH when the PEG-SH was capped on the opposite side. The morphologies of AuNPs membrane and Janus metamaterials membrane support the above mentioned result of SPR. In virtue of tunable SPR band, the Janus metamaterials membrane has great potential application in science-based design of optical sensing sensors and surface-enhanced optic sensitive detection.

Thiol-Based Probe for Electrophilic Natural Products Reveals That Most of the Ammosamides Are Artifacts.

PubMed

Reimer, Daniela; Hughes, Chambers C

2017-01-27

To date, 16 members of the ammosamide family of natural products have been discovered, and except for ammosamide D each of these metabolites is characterized by an unusual chlorinated pyrrolo[4,3,2-de]quinoline skeleton. Several ammosamides have been shown to inhibit quinone reductase 2, a flavoenzyme responsible for quelling toxic oxidative species in cells or for killing cancer cells outright. Treatment of the extract from an ammosamide-producing culture (Streptomyces strain CNR-698) with a thiol-based reagent designed to label electrophilic natural products produced an ammosamide C-thiol adduct. This observation led us to hypothesize, and then demonstrate through experimentation, that all of the other ammosamides are derived from ammosamide C via nonenzymatic processes involving exposure to nucleophiles, air, and light. Like many established electrophilic natural products, reaction with the thiol probe suggests that ammosamide C is itself an electrophilic natural product. Although ammosamide C did not show substantial cytotoxicity against cancer cells, its activity against a marine Bacillus bacterial strain may reflect its ecological role.

Strengthening injectable thermo-sensitive NIPAAm-g-chitosan hydrogels using chemical cross-linking of disulfide bonds as scaffolds for tissue engineering.

PubMed

Wu, Shu-Wei; Liu, Xifeng; Miller, A Lee; Cheng, Yu-Shiuan; Yeh, Ming-Long; Lu, Lichun

2018-07-15

In the present study, we fabricated non-toxic, injectable, and thermo-sensitive NIPAAm-g-chitosan (NC) hydrogels with thiol modification for introduction of disulfide cross-linking strategy. Previously, NIPAAm and chitosan copolymer has been proven to have excellent biocompatibility, biodegradability and rapid phase transition after injection, suitable to serve as cell carriers or implanted scaffolds. However, weak mechanical properties significantly limit their potential for biomedical fields. In order to overcome this issue, we incorporated thiol side chains into chitosan by covalently conjugating N-acetyl-cysteine (NAC) with carbodiimide chemistry to strengthen mechanical properties. After oxidation of thiols into disulfide bonds, modified NC hydrogels did improve the compressive modulus over 9 folds (11.4 kPa). Oscillatory frequency sweep showed a positive correlation between storage modulus and cross-liking density as well. Additionally, there was no cytotoxicity observed to mesenchymal stem cells, fibroblasts and osteoblasts. We suggested that the thiol-modified thermo-sensitive polysaccharide hydrogels are promising to be a cell-laden biomaterial for tissue regeneration. Copyright © 2018 Elsevier Ltd. All rights reserved.

S-allyl derivatives of 6-mercaptopurine are highly potent drugs against human B-CLL through synergism between 6-mercaptopurine and allicin.

PubMed

Miron, Talia; Wilchek, Meir; Shvidel, Lev; Berrebi, Alain; Arditti, Fabian D

2012-12-01

S-allylthio-6-mercaptopurine and its ribose derivative were tested for anti-leukemic activity, using a human- mouse B-CLL model. The novel prodrugs contain two components, a purine analog, which interferes with DNA synthesis, and an S-allylthio, readily engaging in thiol-disulfide exchange reactions. The latter component targets the redox homeostasis which is more sensitive in leukemic cells, than in normal B-cells. Upon administration, the prodrug permeates cells, instantly reacts with free thiol, forming S-allyl mixed disulfides and releasing purine. Several cycles of thiol-disulfide exchange reactions occur, thus extending the duration of the prodrug effects. The concerted action of 2 components, as compared with purine alone, boosted in vitro apoptotis in B-CLL cells from 10% to 38%, and decreased in vivo engraftment of B-CLL from 30% to 0.7%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nanoporous Gold: Fabrication, Characterization, and Applications

PubMed Central

Seker, Erkin; Reed, Michael L.; Begley, Matthew R.

2009-01-01

Nanoporous gold (np-Au) has intriguing material properties that offer potential benefits for many applications due to its high specific surface area, well-characterized thiol-gold surface chemistry, high electrical conductivity, and reduced stiffness. The research on np-Au has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here, we provide a review of the recent advances in np-Au research, with special emphasis on microfabrication and characterization techniques. We conclude the paper with a brief outline of challenges to overcome in the study of nanoporous metals.

Molecular beacon modified sensor chips for oligonucleotide detection with optical readout.

PubMed

Su, Qiang; Wesner, Daniel; Schönherr, Holger; Nöll, Gilbert

2014-12-02

Three different surface bound molecular beacons (MBs) were investigated using surface plasmon fluorescence spectroscopy (SPFS) as an optical readout technique. While MB1 and MB2, both consisting of 36 bases, differed only in the length of the linker for surface attachment, the significantly longer MB3, consisting of 56 bases, comprised an entirely different sequence. For sensor chip preparation, the MBs were chemisorbed on gold via thiol anchors together with different thiol spacers. The influence of important parameters, such as the length of the MBs, the length of the linker between the MBs and the gold surface, the length and nature of the thiol spacers, and the ratio between the MBs and the thiol spacers was studied. After hybridization with the target, the fluorophore of the longer MB3 was oriented close to the surface, and the shorter MBs were standing more or less upright, leading to a larger increase in fluorescence intensity. Fluorescence microscopy revealed a homogeneous distribution of the MBs on the surface. The sensor chips could be used for simple and fast detection of target molecules with a limit of detection in the larger picomolar range. The response time was between 5 and 20 min. Furthermore, it was possible to distinguish between fully complementary and singly mismatched targets. While rinsing with buffer solution after hybridization with target did not result in any signal decrease, complete dehybridization could be carried out by intense rinsing with pure water. The MB modified sensor chips could be prepared in a repeatable manner and reused many times without significant decrease in performance.

Surface Functionalization of Diamond Films by Photoreaction of Elemental Sulfur and Their Surface Properties

NASA Astrophysics Data System (ADS)

Nakamura, Takako; Ohana, Tsuguyori

2012-08-01

A useful method for direct sulfurization of diamond film surfaces by photoreaction of elemental sulfur was developed. The introduction of thiol groups onto the diamond films was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM) analyses. The sulfur-modified diamond films attached to gold nanoparticles by self-assembly. The degrees of thiol group introduction and gold attachment were found to depend on photoirradiation time by monitoring by XPS. The gold-modified diamond film was observed to act as a surface-enhanced Raman scattering substrate for measurement of picric acid.

Effect of adsorbate electrophilicity and spiky uneven surfaces on single gold nanourchin-based localized surface plasmon resonance sensors

NASA Astrophysics Data System (ADS)

Kim, Geun Wan; Ha, Ji Won

2018-04-01

We present single particle studies on gold nanourchins (AuNUs) for their use as localized surface plasmon resonance (LSPR) biosensors under dark-field (DF) microscopy. First, the LSPR wavelength of single AuNUs was red-shifted as thiol molecules were attached onto the surface. AuNUs with sharp tips showed higher sensitivity for detecting thiol molecules than gold nanospheres (AuNSs) of similar size. Second, the degree of red shift was affected by the electrophilicity of adsorbate molecules on the nanoparticle surface. Last, real-time monitoring of molecular binding events on single AuNUs was achieved with introducing 1 μM of 4-aminothiophenol.

A Novel method for the preparation of fluorescent C60 poly(amino acid) composites and their biological imaging.

PubMed

Xu, Dazhuang; Liu, Meiying; Huang, Qiang; Chen, Junyu; Huang, Hongye; Deng, Fengjie; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2018-04-15

Recently, fullerene (C 60 ) and its derivatives have been widely explored for many applications owing to their enriched physical and chemical properties. Specifically, the synthesis and biomedical applications of fluorescent C 60 have been extensively investigated previously. However, the preparation of polymer-functionalized fluorescent C 60 has not been reported thus far. In this study, water-dispersible fluorescent C 60 polymer composites were successfully synthesized through the combination of the thiol-ene click reaction and subsequent ring-opening polymerization. First, 2-aminoethanethiol was introduced on the surface of C 60 by the thiol-ene click reaction. The surface of amino group-functionalized C 60 (C 60 -NH 2 ) was further modified with poly(amino acid)s via ring-open polymerization of GluEG N-carboxyanhydrides (NCAs). The morphology, functional groups, optical properties and biocompatibility were examined by a number of characterization equipment and assays in detail. We demonstrated that the resultant fluorescent C 60 poly(amino acid) (C 60 -GluEG) composites have a small size (about 5 nm), high water dispersibility, intense fluorescence and high photostability. Cell viability results implied that the C 60 -GluEG composites possess low cytotoxicity. Moreover, these C 60 -GluEG composites can easily penetrate into live cells, indicating their great potential for biological imaging applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Highly Stable Bonding of Thiol Monolayers to Hydrogen-Terminated Si via Supercritical Carbon Dioxide: Toward a Super Hydrophobic and Bioresistant Surface.

PubMed

Bhartia, Bhavesh; Puniredd, Sreenivasa Reddy; Jayaraman, Sundaramurthy; Gandhimathi, Chinnasamy; Sharma, Mohit; Kuo, Yen-Chien; Chen, Chia-Hao; Reddy, Venugopal Jayarama; Troadec, Cedric; Srinivasan, Madapusi Palavedu

2016-09-21

Oxide-free silicon chemistry has been widely studied using wet-chemistry methods, but for emerging applications such as molecular electronics on silicon, nanowire-based sensors, and biochips, these methods may not be suitable as they can give rise to defects due to surface contamination, residual solvents, which in turn can affect the grafted monolayer devices for practical applications. Therefore, there is a need for a cleaner, reproducible, scalable, and environmentally benign monolayer grafting process. In this work, monolayers of alkylthiols were deposited on oxide-free semiconductor surfaces using supercritical carbon dioxide (SCCO2) as a carrier fluid owing to its favorable physical properties. The identity of grafted monolayers was monitored with Fourier transform infrared (FTIR) spectroscopy, high-resolution X-ray photoelectron spectroscopy (HRXPS), XPS, atomic force microscopy (AFM), contact angle measurements, and ellipsometry. Monolayers on oxide-free silicon were able to passivate the surface for more than 50 days (10 times than the conventional methods) without any oxide formation in ambient atmosphere. Application of the SCCO2 process was further extended by depositing alkylthiol monolayers on fragile and brittle 1D silicon nanowires (SiNWs) and 2D germanium substrates. With the recent interest in SiNWs for biological applications, the thiol-passivated oxide-free silicon nanowire surfaces were also studied for their biological response. Alkylthiol-functionalized SiNWs showed a significant decrease in cell proliferation owing to their superhydrophobicity combined with the rough surface morphology. Furthermore, tribological studies showed a sharp decrease in the coefficient of friction, which was found to be dependent on the alkyl chain length and surface bond. These studies can be used for the development of cost-effective and highly stable monolayers for practical applications such as solar cells, biosensors, molecular electronics, micro- and nano- electromechanical systems, antifouling agents, and drug delivery.

Labeling Thiols on Proteins, Living Cells, and Tissues with Enhanced Emission Induced by FRET

PubMed Central

Yuan, Yue; Wang, Xijun; Mei, Bin; Zhang, Dongxin; Tang, Anming; An, Linna; He, Xiaoxiao; Jiang, Jun; Liang, Gaolin

2013-01-01

Using N-(2-Aminoethyl)maleimide-cysteine(StBu) (Mal-Cys) as a medium, protein thiols were converted into N-terminal cysteines. After a biocompatible condensation reaction between the N-terminal cysteine and fluorescent probe 2-cyanobenzothiazole-Gly-Gly-Gly-fluorescein isothiocyanate (CBT-GGG-FITC), a new fluorogenic structure Luciferin-GGG-FITC was obtained. The latter exhibits near one order of magnitude (7 folds) enhanced fluorescence emission compared to the precursor moiety due to fluorescence resonance energy transfer (FRET) effect between the newly formed luciferin structure and the FITC motif. Theoretical investigations revealed the underlying mechanism that satisfactorily explained the experimental results. With this method, enhanced fluorescence imaging of thiols on proteins, outer membranes of living cells, translocation of membrane proteins, and endothelial cell layers of small arteries was successfully achieved. PMID:24343586

Labeling Thiols on Proteins, Living Cells, and Tissues with Enhanced Emission Induced by FRET

NASA Astrophysics Data System (ADS)

Yuan, Yue; Wang, Xijun; Mei, Bin; Zhang, Dongxin; Tang, Anming; An, Linna; He, Xiaoxiao; Jiang, Jun; Liang, Gaolin

2013-12-01

Using N-(2-Aminoethyl)maleimide-cysteine(StBu) (Mal-Cys) as a medium, protein thiols were converted into N-terminal cysteines. After a biocompatible condensation reaction between the N-terminal cysteine and fluorescent probe 2-cyanobenzothiazole-Gly-Gly-Gly-fluorescein isothiocyanate (CBT-GGG-FITC), a new fluorogenic structure Luciferin-GGG-FITC was obtained. The latter exhibits near one order of magnitude (7 folds) enhanced fluorescence emission compared to the precursor moiety due to fluorescence resonance energy transfer (FRET) effect between the newly formed luciferin structure and the FITC motif. Theoretical investigations revealed the underlying mechanism that satisfactorily explained the experimental results. With this method, enhanced fluorescence imaging of thiols on proteins, outer membranes of living cells, translocation of membrane proteins, and endothelial cell layers of small arteries was successfully achieved.

Thiol/disulfide redox states in signaling and sensing

PubMed Central

Go, Young-Mi; Jones, Dean P.

2015-01-01

Rapid advances in redox systems biology are creating new opportunities to understand complexities of human disease and contributions of environmental exposures. New understanding of thiol-disulfide systems have occurred during the past decade as a consequence of the discoveries that thiol and disulfide systems are maintained in kinetically controlled steady-states displaced from thermodynamic equilibrium, that a widely distributed family of NADPH oxidases produces oxidants that function in cell signaling, and that a family of peroxiredoxins utilize thioredoxin as a reductant to complement the well-studied glutathione antioxidant system for peroxide elimination and redox regulation. This review focuses on thiol/disulfide redox state in biologic systems and the knowledge base available to support development of integrated redox systems biology models to better understand the function and dysfunction of thiol-disulfide redox systems. In particular, central principles have emerged concerning redox compartmentalization and utility of thiol/disulfide redox measures as indicators of physiologic function. Advances in redox proteomics show that, in addition to functioning in protein active sites and cell signaling, cysteine residues also serve as redox sensors to integrate biologic functions. These advances provide a framework for translation of redox systems biology concepts to practical use in understanding and treating human disease. Biological responses to cadmium, a widespread environmental agent, are used to illustrate the utility of these advances to the understanding of complex pleiotropic toxicities. PMID:23356510

Immobilisation of a thrombopoietin peptidic mimic by self-assembled monolayers for culture of CD34+ cells.

PubMed

Lee, Eun-Ju; Be, Cheang Ly; Vinson, Andrew R; Riches, Andrew G; Fehr, Friederike; Gardiner, James; Gengenbach, Thomas R; Winkler, David A; Haylock, David

2015-01-01

Compared to soluble cytokines, surface-tethered ligands can deliver biological signalling with precise control of spatial positioning and concentration. A strategy that immobilises ligand molecules on a surface in a uniform orientation using non-cleavable linkages under physiological conditions would enhance the specific and systemic delivery of signalling in the local environment. We used mixed self-assembled monolayers (SAMs) of oxyamine- and oligo(ethylene glycol)-terminated thiols on gold to covalently install aldehyde- or ketone-functionalised ligands via oxime conjugation. Characterisation by electrochemistry and X-ray photoelectron spectroscopy showed quantitative immobilisation of the ligands on SAM surfaces. The thrombopoietin mimetic peptide, RILL, was immobilised on SAMs and the bioactivity of the substrate was demonstrated by culturing factor-dependent cells. We also optimised the immobilisation and wash conditions so that the peptide was not released into the culture medium and the immobilised RILL could be re-used for consecutive cell cultures. The surface also supported the growth of haematopoietic CD34+ cells comparable to the standard thrombopoietin-supplemented culture. Furthermore, the RILL-immobilised SAM surface was as effective in expanding uncommitted CD34+ cells as standard culture. The stimulatory effect of surface-tethered ligands in haematopoietic stem cell expansion supports the use of ligand immobilisation strategies to replicate the haematopoietic stem cell niche. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Adaptive aneuploidy protects against thiol peroxidase deficiency by increasing respiration via key mitochondrial proteins.

PubMed

Kaya, Alaattin; Gerashchenko, Maxim V; Seim, Inge; Labarre, Jean; Toledano, Michel B; Gladyshev, Vadim N

2015-08-25

Aerobic respiration is a fundamental energy-generating process; however, there is cost associated with living in an oxygen-rich environment, because partially reduced oxygen species can damage cellular components. Organisms evolved enzymes that alleviate this damage and protect the intracellular milieu, most notably thiol peroxidases, which are abundant and conserved enzymes that mediate hydrogen peroxide signaling and act as the first line of defense against oxidants in nearly all living organisms. Deletion of all eight thiol peroxidase genes in yeast (∆8 strain) is not lethal, but results in slow growth and a high mutation rate. Here we characterized mechanisms that allow yeast cells to survive under conditions of thiol peroxidase deficiency. Two independent ∆8 strains increased mitochondrial content, altered mitochondrial distribution, and became dependent on respiration for growth but they were not hypersensitive to H2O2. In addition, both strains independently acquired a second copy of chromosome XI and increased expression of genes encoded by it. Survival of ∆8 cells was dependent on mitochondrial cytochrome-c peroxidase (CCP1) and UTH1, present on chromosome XI. Coexpression of these genes in ∆8 cells led to the elimination of the extra copy of chromosome XI and improved cell growth, whereas deletion of either gene was lethal. Thus, thiol peroxidase deficiency requires dosage compensation of CCP1 and UTH1 via chromosome XI aneuploidy, wherein these proteins support hydroperoxide removal with the reducing equivalents generated by the electron transport chain. To our knowledge, this is the first evidence of adaptive aneuploidy counteracting oxidative stress.

A quantitative metabolomics peek into planarian regeneration.

PubMed

Natarajan, Nivedita; Ramakrishnan, Padma; Lakshmanan, Vairavan; Palakodeti, Dasaradhi; Rangiah, Kannan

2015-05-21

The fresh water planarian species Schmidtea mediterranea is an emerging stem cell model because of its capability to regenerate a whole animal from a small piece of tissue. It is one of the best model systems to address the basic mechanisms essential for regeneration. Here, we are interested in studying the roles of various amines, thiols and nucleotides in planarian regeneration, stem cell function and growth. We developed mass spectrometry based quantitative methods and validated the differential enrichment of 35 amines, 7 thiol metabolites and 4 nucleotides from both intact and regenerating planarians. Among the amines, alanine in sexual and asparagine in asexual are the highest (>1000 ng/mg) in the intact planarians. The levels of thiols such as cysteine and GSH are 651 and 1107 ng mg(-1) in planarians. Among the nucleotides, the level of cGMP is the lowest (0.03 ng mg(-1)) and the level of AMP is the highest (187 ng mg(-1)) in both of the planarian strains. We also noticed increasing levels of amines in both anterior and posterior regenerating planarians. The blastema from day 3 regenerating planarians also showed higher amounts of many amines. Interestingly, the thiol (cysteine and GSH) levels are well maintained during planarian regeneration. This suggests an inherent and effective mechanism to control induced oxidative stress because of the robust regeneration and stem cell proliferation. Like in intact planarians, the level of cGMP is also very low in regenerating planarians. Surprisingly, the levels of amines and thiols in head regenerating blastemas are ∼3 times higher compared to those for tail regenerating blastemas. Thus our results strongly indicate the potential roles of amines, thiols and nucleotides in planarian regeneration.

Study of Highly Selective and Efficient Thiol Derivatization using Selenium Reagents by Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Kehua; Zhang, Yun W.; Tang, Bo

2010-08-15

Biological thiols are critical physiological components and their detection often involves derivatization. This paper reports a systemic mass spectrometry (MS) investigation of the cleavage of Se-N bond by thiol to form a new Se-S bond, the new selenium chemistry for thiol labeling. Our data shows that the reaction is highly selective, rapid, reversible and efficient. For instance, among twenty amino acids, only cysteine was found to be reactive with Se-N containing reagents and the reaction takes place in seconds. By adding dithiothreitol (DTT), the newly formed Se-S bond of peptides/proteins can be reduced back to free thiol. The high selectivitymore » and excellent reversibility of the reaction provide potential of using this chemistry for selective identification of thiol compounds or enriching and purifying thiol peptides/proteins. In addition, the derivatized thiol peptides have interesting dissociation behavior, which is tunable using different selenium reagents. For example, by introducing an adjacent nucleophilic group into the selenium reagent in the case of using ebselen, the reaction product of ebselen with glutathione (GSH) is easy to lose the selenium tag upon collision-induced dissociation (CID), which is useful to "fish out" those peptides containing free cysteine residues by precursor ion scan. By contrast, the selenium tag of N-(phenylseleno) phthalimide reagent can be stable and survive in CID process, which would be of value in pinpointing thiol location using a top-down proteomic approach. Also, the high conversion yield of the reaction allows the counting of total number of thiol in proteins. We believe that ebselen or N-(phenylseleno) phthalimide as tagging thiol-protein reagents will have important applications in both qualitative and quantitative analysis of different thiol-proteins derived from living cells by MS method.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yu-Rong; Lu, Xia; Zhao, Linduo

Microbial conversion of inorganic mercury (IHg) to methylmercury (MeHg) is a significant environmental concern because of the bioaccumulation and biomagnification of toxic MeHg in the food web. Laboratory incubation studies have shown that, despite the presence of large quantities of IHg in cell cultures, MeHg biosynthesis often reaches a plateau or a maximum within hours or a day by an as yet unexplained mechanism. In this paper, we report that mercuric Hg(II) can be taken up rapidly by cells of Desulfovibrio desulfuricans ND132, but a large fraction of the Hg(II) is unavailable for methylation because of strong cellular sorption. Thiols,more » such as cysteine, glutathione, and penicillamine, added either simultaneously with Hg(II) or after cells have been exposed to Hg(II), effectively desorb or mobilize the bound Hg(II), leading to a substantial increase in MeHg production. The amount of thiol-desorbed Hg(II) is strongly correlated to the amount of MeHg produced (r = 0.98). Furthermore, cells do not preferentially take up Hg(II)–thiol complexes, but Hg(II)–ligand exchange between these complexes and the cell-associated proteins likely constrains Hg(II) uptake and methylation. Finally, we suggest that, aside from aqueous chemical speciation of Hg(II), binding and exchange of Hg(II) between cells and complexing ligands such as thiols and naturally dissolved organics in solution is an important controlling mechanism of Hg(II) bioavailability, which should be considered when predicting MeHg production in the environment.« less

A novel strategy for global analysis of the dynamic thiol redox proteome.

PubMed

Martínez-Acedo, Pablo; Núñez, Estefanía; Gómez, Francisco J Sánchez; Moreno, Margoth; Ramos, Elena; Izquierdo-Álvarez, Alicia; Miró-Casas, Elisabet; Mesa, Raquel; Rodriguez, Patricia; Martínez-Ruiz, Antonio; Dorado, David Garcia; Lamas, Santiago; Vázquez, Jesús

2012-09-01

Nitroxidative stress in cells occurs mainly through the action of reactive nitrogen and oxygen species (RNOS) on protein thiol groups. Reactive nitrogen and oxygen species-mediated protein modifications are associated with pathophysiological states, but can also convey physiological signals. Identification of Cys residues that are modified by oxidative stimuli still poses technical challenges and these changes have never been statistically analyzed from a proteome-wide perspective. Here we show that GELSILOX, a method that combines a robust proteomics protocol with a new computational approach that analyzes variance at the peptide level, allows a simultaneous analysis of dynamic alterations in the redox state of Cys sites and of protein abundance. GELSILOX permits the characterization of the major endothelial redox targets of hydrogen peroxide in endothelial cells and reveals that hypoxia induces a significant increase in the status of oxidized thiols. GELSILOX also detected thiols that are redox-modified by ischemia-reperfusion in heart mitochondria and demonstrated that these alterations are abolished in ischemia-preconditioned animals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toriello, Nicholas M.; Douglas, Erik S.; Mathies, Richard A.

A microchip that performs directed capture and chemical activation of surface-modified single-cells has been developed. The cell-capture system is comprised of interdigitated gold electrodes microfabricated on a glass substrate within PDMS channels. The cell surface is labeled with thiol functional groups using endogenous RGD receptors and adhesion to exposed gold pads on the electrodes is directed by applying a driving electric potential. Multiple cell types can thus be sequentially and selectively captured on desired electrodes. Single-cell capture efficiency is optimized by varying the duration of field application. Maximum single-cell capture is attained for the 10 min trial, with 63+-9 percentmore » (n=30) of the electrode pad rows having a single cell. In activation studies, single M1WT3 CHO cells loaded with the calcium-sensitive dye fluo-4 AM were captured; exposure to the muscarinic agonist carbachol increased the fluorescence to 220+-74percent (n=79) of the original intensity. These results demonstrate the ability to direct the adhesion of selected living single cells on electrodes in a microfluidic device and to analyze their response to chemical stimuli.« less

Is Oxidized Thioredoxin a Major Trigger for Cysteine Oxidation? Clues from a Redox Proteomics Approach

PubMed Central

García-Santamarina, Sarela; Boronat, Susanna; Calvo, Isabel A.; Rodríguez-Gabriel, Miguel; Ayté, José; Molina, Henrik

2013-01-01

Abstract Cysteine oxidation mediates oxidative stress toxicity and signaling. It has been long proposed that the thioredoxin (Trx) system, which consists of Trx and thioredoxin reductase (Trr), is not only involved in recycling classical Trx substrates, such as ribonucleotide reductase, but it also regulates general cytoplasmic thiol homeostasis. To investigate such a role, we have performed a proteome-wide analysis of cells expressing or not the two components of the Trx system. We have compared the reversibly oxidized thiol proteomes of wild-type Schizosaccharomyces pombe cells with mutants lacking Trx or Trr. Specific Trx substrates are reversibly-oxidized in both strain backgrounds; however, in the absence of Trr, Trx can weakly recycle its substrates at the expense of an alternative electron donor. A massive thiol oxidation occurs only in cells lacking Trr, with 30% of all cysteine-containing peptides being reversibly oxidized; this oxidized cysteine proteome depends on the presence of Trxs. Our observations lead to the hypothesis that, in the absence of its reductase, the natural electron donor Trx becomes a powerful oxidant and triggers general thiol oxidation. Antioxid. Redox Signal. 18, 1549–1556. PMID:23121505

Facile thiol-ene thermal crosslinking reaction facilitated hole-transporting layer for highly efficient and stable perovskite solar cells

DOE PAGES

Li, Zhong'an; Zhu, Zonglong; Chueh, Chu -Chen; ...

2016-08-08

A crosslinked organic hole-transporting layer (HTL) is developed to realize highly efficient and stable perovskite solar cells via a facile thiol-ene thermal reaction. This crosslinked HTL not only facilitates hole extraction from perovskites, but also functions as an effective protective barrier. Lastly, a high-performance (power conversion efficiency: 18.3%) device is demonstrated to show respectable photo and thermal stability without encapsulation.

N-acetylcysteine potentiates platelet inhibition by endothelium-derived relaxing factor.

PubMed

Stamler, J; Mendelsohn, M E; Amarante, P; Smick, D; Andon, N; Davies, P F; Cooke, J P; Loscalzo, J

1989-09-01

Recent evidence suggests that endothelium-derived relaxing factor exhibits properties of nitric oxide. Like nitric oxide, it inhibits platelet function and mediates its effects by elevating intracellular cyclic GMP. In this study we have investigated the role of reduced thiol in the mechanism of action of endothelium-derived relaxing factor on platelets. Bovine aortic endothelial cells were grown on microcarrier beads and pretreated with aspirin before use. Endothelial cells stimulated with bradykinin or exposed to stirred medium expressed a dose-dependent inhibition of platelet aggregation that was potentiated by the reduced thiol, N-acetylcysteine. Endothelial cell-mediated platelet inhibition was attenuated by methylene blue. Inhibition of platelet aggregation by endothelial cells was associated with a rise in platelet intracellular cyclic GMP, an effect that was enhanced by N-acetylcysteine. These data show that 1) the reduced thiol N-acetylcysteine potentiates platelet inhibition by endothelium-derived relaxing factor and 2) this effect is associated with increasing intracellular platelet cyclic GMP levels.

Thermodynamics of Alkanethiol Self-Assembled Monolayer Assembly on Pd Surfaces.

PubMed

Kumar, Gaurav; Van Cleve, Timothy; Park, Jiyun; van Duin, Adri; Medlin, J Will; Janik, Michael J

2018-06-05

We investigate the structure and binding energy of alkanethiolate self-assembled monolayers (SAMs) on Pd (111), Pd (100), and Pd (110) facets at different coverages. Dispersion-corrected density functional theory calculations are used to correlate the binding energy of alkanethiolates with alkyl chain length and coverage. The equilibrium coverage of thiolate layers strongly prefers 1/3 monolayer (ML) on the Pd (111) surface. The coverage of thiolates varies with chemical potential on Pd (100) and Pd (110), increasing from 1/3 to 1/2 ML on (100) and from 1/4 to 1/2 ML on (110) as the thiol chemical potential is increased. Higher coverages are driven by attractive dispersion interactions between the extended alkyl chains, such that transitions to higher coverages occur at lower thiol chemical potentials for longer chain thiolates. Stronger adsorption to the Pd (100) surface causes the equilibrium Wulff construction of Pd particles to take on a cubic shape upon saturation with thiols. The binding of H, O, and CO adsorbates is weakened as the thiolate coverage is increased, with saturation coverages causing unfavorable binding of O and CO on Pd (100) and weakened binding on other facets. Temperature-dependent CO diffuse reflectance infrared Fourier transform spectroscopy experiments are used to corroborate the weakened binding of CO in the presence of thiolate SAMs of varying surface density. Preliminary results of multiscale modeling efforts on the Pd-thiol system using a reactive force field, ReaxFF, are also discussed.

A noticeable phenomenon: thiol terminal PEG enhances the immunogenicity of PEGylated emulsions injected intravenously or subcutaneously into rats.

PubMed

Wang, Chunling; Cheng, Xiaobo; Sui, Yue; Luo, Xiang; Jiang, Gongping; Wang, Yu; Huang, Zhenjun; She, Zhennan; Deng, Yihui

2013-11-01

Repeated intravenous injection of long-circulating methoxy-polyethylene glycol (PEG)-liposomes alters the pharmacokinetics and biodistribution of the second administration, regarded as the "accelerated blood clearance (ABC) phenomenon." Nevertheless, the effect of terminal groups of distearoylphosphatidylethanolamine-polyethylene glycol (DSPE-PEG) on the induction of the ABC phenomenon had not been reported previously. In this study, rats were injected intravenously or subcutaneously with PEG coated emulsions (DE) which were prepared using PEG terminated with either the methoxyl (OCH3), hydroxyl (OH), amino (NH2), carboxyl (COOH), or thiol (SH) group. DE-OCH3 demonstrated the longest prolonged half-life in vivo after a single intravenous injection, followed by DE-SH and DE-COOH. In contrast, DE-OH was rapidly removed from the blood circulation, as was DE-NH2. Moreover, we observed a strong positive relationship between the circulation time of initially injected PEGylated emulsions and the extent to which the ABC phenomenon was induced, but a exception of DE-SH increasing the ABC effect. Furthermore, the present study suggested that thiols might stimulate the proliferation and differentiation of B cells to induce the fastest clearance of the second intravenous administration by inducing the synthesis of the cell membrane and cytosolic proteins or reacting with follicular dendritic cells. The results strongly suggested that thiol groups played a stimulatory role in the immune response and provided a considerable implication for multiple drug therapy of thiol groups. Copyright © 2013 Elsevier B.V. All rights reserved.

Deficient expression of aldehyde dehydrogenase 1A1 is consistent with increased sensitivity of Gorlin syndrome patients to radiation carcinogenesis

DOE PAGES

Wright, Aaron T.; Magnaldo, Thierry; Sontag, Ryan L.; ...

2013-11-27

Human phenotypes that are highly susceptible to radiation carcinogenesis have been identified. Sensitive phenotypes often display robust regulation of molecular features that modify biological response, which can facilitate identification of relevant pathways/networks. Here we interrogate primary dermal fibroblasts isolated from Gorlin syndrome patients (GDFs), who display a pronounced tumorigenic response to radiation, in comparison to normal human dermal fibroblasts (NHDFs). Our approach exploits newly developed thiol-reactive probes with a flexible click chemistry functional group to define changes in protein thiol profiles in live cell studies, which minimizes artifacts associated with cell lysis. We observe qualitative differences in protein thiol profilesmore » by SDS-PAGE analysis when detection by iodoacetamide vs maleimide probe chemistries are compared, and pretreatment of cells with hydrogen peroxide eliminates detection of the majority of SDS-PAGE bands. Redox probes revealed deficient expression of an apparent 55 kDa protein thiol in GDFs from independent donors, compared with NHDFs. Proteomics tentatively identified this protein as aldehyde dehydrogenase 1A1 (ALDH1A1), a key enzyme regulating retinoic acid synthesis, and this deficiency was confirmed by Western blot. Redox probes revealed additional protein thiol differences between GDFs and NHDFs, including radiation responsive annexin family members. Our results indicate a multifactorial basis for the unusual sensitivity of Gorlin syndrome to radiation carcinogenesis, and the pathways identified have plausible implications for radiation health effects.« less

Deficient expression of aldehyde dehydrogenase 1A1 is consistent with increased sensitivity of Gorlin syndrome patients to radiation carcinogenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, Aaron T.; Magnaldo, Thierry; Sontag, Ryan L.

Human phenotypes that are highly susceptible to radiation carcinogenesis have been identified. Sensitive phenotypes often display robust regulation of molecular features that modify biological response, which can facilitate identification of relevant pathways/networks. Here we interrogate primary dermal fibroblasts isolated from Gorlin syndrome patients (GDFs), who display a pronounced tumorigenic response to radiation, in comparison to normal human dermal fibroblasts (NHDFs). Our approach exploits newly developed thiol-reactive probes with a flexible click chemistry functional group to define changes in protein thiol profiles in live cell studies, which minimizes artifacts associated with cell lysis. We observe qualitative differences in protein thiol profilesmore » by SDS-PAGE analysis when detection by iodoacetamide vs maleimide probe chemistries are compared, and pretreatment of cells with hydrogen peroxide eliminates detection of the majority of SDS-PAGE bands. Redox probes revealed deficient expression of an apparent 55 kDa protein thiol in GDFs from independent donors, compared with NHDFs. Proteomics tentatively identified this protein as aldehyde dehydrogenase 1A1 (ALDH1A1), a key enzyme regulating retinoic acid synthesis, and this deficiency was confirmed by Western blot. Redox probes revealed additional protein thiol differences between GDFs and NHDFs, including radiation responsive annexin family members. Our results indicate a multifactorial basis for the unusual sensitivity of Gorlin syndrome to radiation carcinogenesis, and the pathways identified have plausible implications for radiation health effects.« less

Kinetics and mechanisms of thiol-disulfide exchange covering direct substitution and thiol oxidation-mediated pathways.

PubMed

Nagy, Péter

2013-05-01

Disulfides are important building blocks in the secondary and tertiary structures of proteins, serving as inter- and intra-subunit cross links. Disulfides are also the major products of thiol oxidation, a process that has primary roles in defense mechanisms against oxidative stress and in redox regulation of cell signaling. Although disulfides are relatively stable, their reduction, isomerisation, and interconversion as well as their production reactions are catalyzed by delicate enzyme machineries, providing a dynamic system in biology. Redox homeostasis, a thermodynamic parameter that determines which reactions can occur in cellular compartments, is also balanced by the thiol-disulfide pool. However, it is the kinetic properties of the reactions that best represent cell dynamics, because the partitioning of the possible reactions depends on kinetic parameters. This review is focused on the kinetics and mechanisms of thiol-disulfide substitution and redox reactions. It summarizes the challenges and advances that are associated with kinetic investigations in small molecular and enzymatic systems from a rigorous chemical perspective using biological examples. The most important parameters that influence reaction rates are discussed in detail. Kinetic studies of proteins are more challenging than small molecules, and quite often investigators are forced to sacrifice the rigor of the experimental approach to obtain the important kinetic and mechanistic information. However, recent technological advances allow a more comprehensive analysis of enzymatic systems via using the systematic kinetics apparatus that was developed for small molecule reactions, which is expected to provide further insight into the cell's machinery.

Localized gene delivery using antibody tethered adenovirus from polyurethane heart valve cusps and intra-aortic implants.

PubMed

Stachelek, S J; Song, C; Alferiev, I; Defelice, S; Cui, X; Connolly, J M; Bianco, R W; Levy, R J

2004-01-01

The present study investigated a novel approach for gene therapy of heart valve disease and vascular disorders. We formulated and characterized implantable polyurethane films that could also function as gene delivery systems through the surface attachment of replication defective adenoviruses using an anti-adenovirus antibody tethering mechanism. Our hypothesis was that we could achieve site-specific gene delivery to cells interacting with these polyurethane implants, and thereby demonstrate the potential for intravascular devices that could also function as gene delivery platforms for therapeutic vectors. Previous research by our group has demonstrated that polyurethane elastomers can be derivatized post-polymerization through a series of chemical reactions activating the hard segment amide groups with alkyl bromine residues, which can enable a wide variety of subsequent chemical modifications. Furthermore, prior research by our group investigating gene delivery intravascular stents has shown that collagen-coated balloon expandable stents can be configured with anti-adenovirus antibodies via thiol-based chemistry, and can then tether adenoviral vectors at doses that lead to high levels of localized arterial neointima expression, but with virtually no distal spread of vector. Thus, we sought to create two-device configurations for our investigations building on this previous research. (1) Polyurethane films coated with Type I collagen were thiol activated to permit covalent attachment of anti-adenovirus antibodies to enable gene delivery via vector tethering. (2) We also formulated polyurethane films with direct covalent attachment of anti-adenovirus antibodies to polyurethane hard segments derivatized with alkyl-thiol groups, thereby also enabling tethering of replication-defective adenoviruses. Both formulations demonstrated highly localized and efficient transduction in cell culture studies with rat arterial smooth muscle cells. In vivo experiments with collagen-coated polyurethane films investigated an abdominal aorta implant model in pigs using a button configuration that simulated the blood contacting environment of a vascular graft. One week explants of the collagen-coated polyurethane films demonstrated 14.3+/-2.5% of neointimal cells on the surface of the implant transduced with green fluorescent protein - adenovirus (AdGFP) vector loadings of 1 x 10(8) PFU. PCR studies demonstrated no detectable vector DNA in blood or distal organs. Similarly, polyurethane films with direct attachment of antivector antibodies to the surface were used in sheep pulmonary valve leaflet replacement studies, simulating the blood contacting environment of a prosthetic heart valve cusp. Polyurethane films with antibody tethered AdGFP vector (10(8) PFU) demonstrated 25.1+/-5.7% of attached cells transduced in these 1 week studies, with no detectable vector DNA in blood or distal organs. In vivo GFP expression was confirmed with immunohistochemistry. It is concluded that site-specific intravascular delivery of adenoviral vectors for gene therapy can be achieved with polyurethane implants utilizing the antivector antibody tethering mechanism.

Novel photonic technique creates micrometer resolution protein arrays and provides a new approach to coupling of genes, peptide hormones and drugs to nanoparticle carriers

NASA Astrophysics Data System (ADS)

Duroux, M.; Duroux, L.; Neves-Petersen, M. T.; Skovsen, E.; Petersen, S. B.

2007-07-01

We demonstrate that ultraviolet light can be used to make sterically oriented covalent immobilization of a large variety of protein molecules onto either thiolated quartz, gold or silicon. The reaction mechanism behind the reported new technology involves light-induced breakage of disulphide bridges in proteins upon UV illumination of nearby aromatic amino acids, resulting in the formation of free, reactive thiol groups that will form covalent bonds with thiol reactive surfaces. In general, the protein molecules retain their function. The size of the immobilization spot is limited to the focal point of illumination being as small as a few micrometers. This new technology allows for dense packing of different bio-molecules on a surface, allowing the creation of multi-potent functionalised new materials, such as nano-biosensors. We have developed the necessary technology for preparing large protein arrays of enzymes and fragments of monoclonal antibodies. Dedicated image processing software has been developed for making quality assessment of the protein arrays. This novel technology is ideal to couple drugs and other bio-molecules to nanoparticles which can be used as carriers into cells for therapeutic purposes.

Selenite Protection of Tellurite Toxicity Toward Escherichia coli

PubMed Central

Vrionis, Helen A.; Wang, Siyuan; Haslam, Bronwyn; Turner, Raymond J.

2015-01-01

In this work the influence of selenite on metal resistance in Escherichia coli was examined. Both synergistic and antagonistic resistance and toxicities were found upon co exposure with selenite. In wild type cells co-exposure to selenite had little effect on arsenic resistance, decreased resistance to cadmium and mercury but led to a dramatically increased resistance to tellurite of 32-fold. Due to the potential importance of thiol chemistry in metal biochemistry, deletion strains in γ-glutamylcysteine synthetase (key step in glutathione biosynthesis, encoded by gshA), thioredoxin (trxA), glutaredoxin (grxA), glutathione oxidoreductase (gor), and the periplasmic glutathione transporter (cydD) were also evaluated for resistance to various metals in the presence of selenite. The protective effect of selenite on tellurite toxicity was seen in several of the mutants and was pronounced in the gshA mutant were resistance to tellurite was increased up to 1000-fold relative to growth in the absence of selenite. Thiol oxidation studies revealed a faster rate of loss of reduced thiol content in the cell with selenite than with tellurite, indicating differential thiol reactivity. Selenite addition resulted in reactive oxygen species (ROS) production equivalent to levels associated with H2O2 addition. Tellurite addition resulted in considerably lower ROS generation while vanadate and chromate treatment did not increase ROS production above that of background. This work shows increased resistance toward most oxyanions in mutants of thiol redox suggesting that metalloid reaction with thiol components such as glutathione actually enhances toxicity of some metalloids. PMID:26732755

Surface plasmon resonance based spectrophotometric determination of medicinally important thiol compounds using unmodified silver nanoparticles

NASA Astrophysics Data System (ADS)

Vaishnav, Sandeep K.; Patel, Kuleshwar; Chandraker, Kumudini; Korram, Jyoti; Nagwanshi, Rekha; Ghosh, Kallol K.; Satnami, Manmohan L.

2017-05-01

The determination of thiol based biological molecules and drugs, such as cysteine (Cys) (I), α-lipoic acid (II), and sodium 2-sulfanylethane sulphonate (Mesna (III)) in human plasma are becoming progressively more important due to the growing body of knowledge about their essential role in numerous biological pathways. Herein we demonstrate a sensitive colorimetric sensor for the determination of medicinally important thiol drugs based on aggregation of the citrate capped silver nanoparticles (Ag NPs). This approach exploited the high affinity of thiols towards the Ag NPs surface which could tempt replacement of the citrate shell by the thiolate shell of target molecules, resulting in aggregation of the NPs through intermolecular electrostatic interaction or hydrogen-bonding. Because of aggregation, the plasmon band at around 400 nm decreases gradually, along with the appearance of a new band connoting a red shift. The calibration curves are derived from the intensity ratios of A530/A400, which display a linear relation in the range of 1 μM-150 μM, 5 μM-200 μM and 10 μM-130 μM, respectively. The obtained detection limits (3σ) were found to be 1.5 μM, 5.6 μM and 10.2 μM for compound I-III, respectively. The proposed method has been successfully applied for the detection of thiol compounds in real samples.

Proteome-wide detection and quantitative analysis of irreversible cysteine oxidation using long column UPLC-pSRM.

PubMed

Lee, Chia-Fang; Paull, Tanya T; Person, Maria D

2013-10-04

Reactive oxygen species (ROS) play an important role in normal biological functions and pathological processes. ROS is one of the driving forces for oxidizing proteins, especially on cysteine thiols. The labile, transient, and dynamic nature of oxidative modifications poses enormous technical challenges for both accurate modification site determination and quantitation of cysteine thiols. The present study describes a mass spectrometry-based approach that allows effective discovery and quantification of irreversible cysteine modifications. The utilization of a long reverse phase column provides high-resolution chromatography to separate different forms of modified cysteine thiols from protein complexes or cell lysates. This Fourier transform mass spectrometry (FT-MS) approach enabled detection and quantitation of ataxia telangiectasia mutated (ATM) complex cysteine sulfoxidation states using Skyline MS1 filtering. When we applied the long column ultra high pressure liquid chromatography (UPLC)-MS/MS analysis, 61 and 44 peptides from cell lysates and cells were identified with cysteine modifications in response to in vitro and in vivo H2O2 oxidation, respectively. Long column ultra high pressure liquid chromatography pseudo selected reaction monitoring (UPLC-pSRM) was then developed to monitor the oxidative level of cysteine thiols in cell lysate under varying concentrations of H2O2 treatment. From UPLC-pSRM analysis, the dynamic conversion of sulfinic (S-O2H) and sulfonic acid (S-O3H) was observed within nucleoside diphosphate kinase (Nm23-H1) and heat shock 70 kDa protein 8 (Hsc70). These methods are suitable for proteome-wide studies, providing a highly sensitive, straightforward approach to identify proteins containing redox-sensitive cysteine thiols in biological systems.

Functionalized boron nitride nanotubes

DOEpatents

Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

2014-04-22

A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

Photoactivatable protein labeling by singlet oxygen mediated reactions.

PubMed

To, Tsz-Leung; Medzihradszky, Katalin F; Burlingame, Alma L; DeGrado, William F; Jo, Hyunil; Shu, Xiaokun

2016-07-15

Protein-protein interactions regulate many biological processes. Identification of interacting proteins is thus an important step toward molecular understanding of cell signaling. The aim of this study was to investigate the use of photo-generated singlet oxygen and a small molecule for proximity labeling of interacting proteins in cellular environment. The protein of interest (POI) was fused with a small singlet oxygen photosensitizer (miniSOG), which generates singlet oxygen ((1)O2) upon irradiation. The locally generated singlet oxygen then activated a biotin-conjugated thiol molecule to form a covalent bond with the proteins nearby. The labeled proteins can then be separated and subsequently identified by mass spectrometry. To demonstrate the applicability of this labeling technology, we fused the miniSOG to Skp2, an F-box protein of the SCF ubiquitin ligase, and expressed the fusion protein in mammalian cells and identified that the surface cysteine of its interacting partner Skp1 was labeled by the biotin-thiol molecule. This photoactivatable protein labeling method may find important applications including identification of weak and transient protein-protein interactions in the native cellular context, as well as spatial and temporal control of protein labeling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Current status of the thiol redox model for the regulation of hexose transport by insulin.

PubMed

Czech, M P

1976-12-01

Data obtained over the last two years pertinent to the thiol redox model for the modulation of hexose transport activity by insulin is summarized. The model proposes that activation of hexose transport in fat cells involves sulfhydryl oxidation to the disulfide form in a key protein component of the fat cell surface membrane. Theoretically, the rapid activation of transport by insulin may involve either the conversion of inactive membrane carriers to the active form as originally proposed, or the conversion of a low Vmax transport system to a high Vmax form. The present experiments showed that the percent inhibition of insulin-activated transport rates by submaximal levels of cytochalasin B was decreased compared to its effects on basal transport. Treatment of fat cells with N-ethylmaleimide inhibited cytochalasin B action but not transport activity. When insulin or the oxidant vitamin K5 was added to cells 5 minutes before the N-ethylmaleimide, the elevated transport activity was also resistant to the sulfhydryl reagent, but cytochalasin B retained its potent inhibitory effect on transport. The data demonstrate that unique properties characterize basal versus insulin-activated transport activity with respect to the sensitivity of cytochalasin B action to sulfhydryl blockade in isolated fat cells. The data are consistent with the concept that activation of transport activity reflects the conversion of a reduced (sulfhydryl) system characterized by a low Vmax to an oxidized (disulfide), high Vmax transport system.

Effects of cellular sorption on mercury bioavailability and methylmercury production by Desulfovibrio desulfuricans ND132

DOE PAGES

Liu, Yu-Rong; Lu, Xia; Zhao, Linduo; ...

2016-11-14

Microbial conversion of inorganic mercury (IHg) to methylmercury (MeHg) is a significant environmental concern because of the bioaccumulation and biomagnification of toxic MeHg in the food web. Laboratory incubation studies have shown that, despite the presence of large quantities of IHg in cell cultures, MeHg biosynthesis often reaches a plateau or a maximum within hours or a day by an as yet unexplained mechanism. In this paper, we report that mercuric Hg(II) can be taken up rapidly by cells of Desulfovibrio desulfuricans ND132, but a large fraction of the Hg(II) is unavailable for methylation because of strong cellular sorption. Thiols,more » such as cysteine, glutathione, and penicillamine, added either simultaneously with Hg(II) or after cells have been exposed to Hg(II), effectively desorb or mobilize the bound Hg(II), leading to a substantial increase in MeHg production. The amount of thiol-desorbed Hg(II) is strongly correlated to the amount of MeHg produced (r = 0.98). Furthermore, cells do not preferentially take up Hg(II)–thiol complexes, but Hg(II)–ligand exchange between these complexes and the cell-associated proteins likely constrains Hg(II) uptake and methylation. Finally, we suggest that, aside from aqueous chemical speciation of Hg(II), binding and exchange of Hg(II) between cells and complexing ligands such as thiols and naturally dissolved organics in solution is an important controlling mechanism of Hg(II) bioavailability, which should be considered when predicting MeHg production in the environment.« less

EPR Characterization of Dinitrosyl Iron Complexes with Thiol-Containing Ligands as an Approach to Their Identification in Biological Objects: An Overview.

PubMed

Vanin, Anatoly F

2018-06-01

The overview demonstrates how the use of only one physico-chemical approach, viz., the electron paramagnetic resonance method, allowed detection and identification of dinitrosyl iron complexes with thiol-containing ligands in various animal and bacterial cells. These complexes are formed in biological objects in the paramagnetic (electron paramagnetic resonance-active) mononuclear and diamagnetic (electron paramagnetic resonance-silent) binuclear forms and control the activity of nitrogen monoxide, one of the most universal regulators of metabolic processes in the organism. The analysis of electronic and spatial structures of dinitrosyl iron complex sheds additional light on the mechanism whereby dinitrosyl iron complex with thiol-containing ligands function in human and animal cells as donors of nitrogen monoxide and its ionized form, viz., nitrosonium ions (NO + ).

Thiol peroxidases mediate specific genome-wide regulation of gene expression in response to hydrogen peroxide

PubMed Central

Fomenko, Dmitri E.; Koc, Ahmet; Agisheva, Natalia; Jacobsen, Michael; Kaya, Alaattin; Malinouski, Mikalai; Rutherford, Julian C.; Siu, Kam-Leung; Jin, Dong-Yan; Winge, Dennis R.; Gladyshev, Vadim N.

2011-01-01

Hydrogen peroxide is thought to regulate cellular processes by direct oxidation of numerous cellular proteins, whereas antioxidants, most notably thiol peroxidases, are thought to reduce peroxides and inhibit H2O2 response. However, thiol peroxidases have also been implicated in activation of transcription factors and signaling. It remains unclear if these enzymes stimulate or inhibit redox regulation and whether this regulation is widespread or limited to a few cellular components. Herein, we found that Saccharomyces cerevisiae cells lacking all eight thiol peroxidases were viable and withstood redox stresses. They transcriptionally responded to various redox treatments, but were unable to activate and repress gene expression in response to H2O2. Further studies involving redox transcription factors suggested that thiol peroxidases are major regulators of global gene expression in response to H2O2. The data suggest that thiol peroxidases sense and transfer oxidative signals to the signaling proteins and regulate transcription, whereas a direct interaction between H2O2 and other cellular proteins plays a secondary role. PMID:21282621

Irreversible bonding of polyimide and polydimethylsiloxane (PDMS) based on a thiol-epoxy click reaction

NASA Astrophysics Data System (ADS)

Hoang, Michelle V.; Chung, Hyun-Joong; Elias, Anastasia L.

2016-10-01

Polyimide is one of the most popular substrate materials for the microfabrication of flexible electronics, while polydimethylsiloxane (PDMS) is the most widely used stretchable substrate/encapsulant material. These two polymers are essential in fabricating devices for microfluidics, bioelectronics, and the internet of things; bonding these materials together is a crucial challenge. In this work, we employ click chemistry at room temperature to irreversibly bond polyimide and PDMS through thiol-epoxy bonds using two different methods. In the first method, we functionalize the surfaces of the PDMS and polyimide substrates with mercaptosilanes and epoxysilanes, respectively, for the formation of a thiol-epoxy bond in the click reaction. In the second method, we functionalize one or both surfaces with mercaptosilane and introduce an epoxy adhesive layer between the two surfaces. When the surfaces are bonded using the epoxy adhesive without any surface functionalization, an extremely small peel strength (<0.01 N mm-1) is measured with a peel test, and adhesive failure occurs at the PDMS surface. With surface functionalization, however, remarkably higher peel strengths of ~0.2 N mm-1 (method 1) and  >0.3 N mm-1 (method 2) are observed, and failure occurs by tearing of the PDMS layer. We envision that the novel processing route employing click chemistry can be utilized in various cases of stretchable and flexible device fabrication.

A site-directed mutagenesis analysis of tNOX functional domains

NASA Technical Reports Server (NTRS)

Chueh, Pin-Ju; Morre, Dorothy M.; Morre, D. James

2002-01-01

Constitutive NADH oxidase proteins of the mammalian cell surface exhibit two different activities, oxidation of hydroquinones (or NADH) and protein disulfide-thiol interchange which alternate to yield oscillatory patterns with period lengths of 24 min. A drug-responsive tNOX (tumor-associated NADH oxidase) has a period length of about 22 min. The tNOX cDNA has been cloned and expressed. These two proteins are representative of cycling oxidase proteins of the plant and animal cell surface. In this report, we describe a series of eight amino acid replacements in tNOX which, when expressed in Escherichia coli, were analyzed for enzymatic activity, drug response and period length. Replacement sites selected include six cysteines that lie within the processed plasma membrane (34 kDa) form of the protein, and amino acids located in putative drug and adenine nucleotide (NADH) binding domains. The latter, plus two of the cysteine replacements, resulted in a loss of enzymatic activity. The recombinant tNOX with the modified drug binding site retained activity but the activity was no longer drug-responsive. The four remaining cysteine replacements were of interest in that both activity and drug response were retained but the period length for both NADH oxidation and protein disulfide-thiol interchange was increased from 22 min to 36 or 42 min. The findings confirm the correctness of the drug and adenine nucleotide binding motifs within the tNOX protein and imply a potential critical role of cysteine residues in determining the period length.

Tunable coating of gold nanostars: tailoring robust SERS labels for cell imaging

NASA Astrophysics Data System (ADS)

Bassi, B.; Taglietti, A.; Galinetto, P.; Marchesi, N.; Pascale, A.; Cabrini, E.; Pallavicini, P.; Dacarro, G.

2016-07-01

Surface modification of noble metal nanoparticles with mixed molecular monolayers is one of the most powerful tools in nanotechnology, and is used to impart and tune new complex surface properties. In imaging techniques based on surface enhanced Raman spectroscopy (SERS), precise and controllable surface modifications are needed to carefully design reproducible, robust and adjustable SERS nanoprobes. We report here the attainment of SERS labels based on gold nanostars (GNSs) coated with a mixed monolayer composed of a poly ethylene glycol (PEG) thiol (neutral or negatively charged) that ensure stability in biological environments, and of a signalling unit 7-Mercapto-4-methylcoumarin as a Raman reporter molecule. The composition of the coating mixture is precisely controlled using an original method, allowing the modulation of the SERS intensity and ensuring overall nanoprobe stability. The further addition of a positively charged layer of poly (allylamine hydrocloride) on the surface of negatively charged SERS labels does not change the SERS response, but it promotes the penetration of GNSs in SH-SY5Y neuroblastoma cells. As an example of an application of such an approach, we demonstrate here the internalization of these new labels by means of visualization of cell morphology obtained with SERS mapping.

Efficient and accelerated growth of multifunctional dendrimers using orthogonal thiol-ene and SN2 reactions.

PubMed

Kottari, Naresh; Chabre, Yoann M; Shiao, Tze Chieh; Rej, Rabindra; Roy, René

2014-02-25

An orthogonal coupling strategy was developed by combining thiol-ene and SN2 reactions, which was subsequently applied to the accelerated synthesis of multifunctional dendrimers using carbohydrate building blocks. In surface plasmon resonance (SPR) studies, the β-d-galactopyranoside-coated dendrimer exhibited nM binding affinity with the bacterial LecA lectin extracted from Pseudomonas aeruginosa.

Ultrasensitive quantum dot fluorescence quenching assay for selective detection of mercury ions in drinking water.

PubMed

Ke, Jun; Li, Xinyong; Zhao, Qidong; Hou, Yang; Chen, Junhong

2014-07-09

Mercury is one of the most acutely toxic substances at trace level to human health and living thing. Developing a rapid, cheap and water soluble metal sensor for detecting mercury ions at ppb level remains a challenge. Herein, a metal sensor consisting of MPA coated Mn doped ZnSe/ZnS colloidal nanoparticles was utilized to ultrasensitively and selectively detect Hg(2+) ions with a low detection limit (0.1 nM) over a dynamic range from 0 to 20 nM. According to strong interaction between thiol(s) and mercury ions, mercaptopropionic acid (MPA) was used as a highly unique acceptor for mercury ions in the as-obtained ultrasensitive sensor. In the presence of mercury ions, colloidal nanoparticles rapidly agglomerated due to changes of surface chemical properties, which results in severe quenching of fluorescent intensity. Meanwhile, we find that the original ligands are separated from the surface of colloidal nanoparticles involving strongly chelation between mercury ion and thiol(s) proved by controlled IR analysis. The result shows that the QD-based metal ions sensor possesses satisfactory precision, high sensitivity and selectivity, and could be applied for the quantification analysis of real samples.

Ultrasensitive Quantum Dot Fluorescence quenching Assay for Selective Detection of Mercury Ions in Drinking Water

PubMed Central

Ke, Jun; Li, Xinyong; Zhao, Qidong; Hou, Yang; Chen, Junhong

2014-01-01

Mercury is one of the most acutely toxic substances at trace level to human health and living thing. Developing a rapid, cheap and water soluble metal sensor for detecting mercury ions at ppb level remains a challenge. Herein, a metal sensor consisting of MPA coated Mn doped ZnSe/ZnS colloidal nanoparticles was utilized to ultrasensitively and selectively detect Hg2+ ions with a low detection limit (0.1 nM) over a dynamic range from 0 to 20 nM. According to strong interaction between thiol(s) and mercury ions, mercaptopropionic acid (MPA) was used as a highly unique acceptor for mercury ions in the as-obtained ultrasensitive sensor. In the presence of mercury ions, colloidal nanoparticles rapidly agglomerated due to changes of surface chemical properties, which results in severe quenching of fluorescent intensity. Meanwhile, we find that the original ligands are separated from the surface of colloidal nanoparticles involving strongly chelation between mercury ion and thiol(s) proved by controlled IR analysis. The result shows that the QD-based metal ions sensor possesses satisfactory precision, high sensitivity and selectivity, and could be applied for the quantification analysis of real samples. PMID:25005836

Thiol surface complexation on growing CdS clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swayambunathan, V.; Hayes, D.; Schmidt, K.H.

1990-05-09

The growth of small CdS colloidal particles has been initiated by pulse radiolytic release of sulfide from thiol (3-mercapto-1,2-propanediol, RSH) in the presence of Cd{sup 2+} ions. The kinetics and stoichiometry of the ensuring reactions were followed by conductivity, absorption spectroscopy, and light-scattering techniques. The final CdS product has been identified by electron diffraction. The formation of Cd-thiolate complexes at the surface of the particles is indicated by conductivity and by energy dispersive analysis of X-ray (EDAX) results. The rate of formation of CdS clusters is strongly pH dependent due to the pH effect on the stability of Dd{sup 2+}/HS{supmore » {minus}} complexes. At low pHs (4.0-5.3) the growth mechanism is proposed to be primarily a cluster-molecule process. At this pH range Cd{sup 2+} ions at the CdS particle surface complex with thiolate ions stronger than in the bulk of the solution. The size control of the particles by thiols is proposed to result from a competition of thiolate ions with HS{sup {minus}} ions for cadmium ions at the surface of the growing particles.« less

Redox biology of the intestine

PubMed Central

Circu, Magdalena L.; Aw, Tak Yee

2011-01-01

The intestinal tract, known for its capability for self-renew, represents the first barrier of defense between the organism and its luminal environment. The thiol/disulfide redox systems comprising the glutathione/glutathione disulfide (GSH/GSSG), cysteine/cystine (Cys/CySS) and reduced and oxidized thioredoxin (Trx/TrxSS) redox couples play important roles in preserving tissue redox homeostasis, metabolic functions, and cellular integrity. Control of the thiol-disulfide status at the luminal surface is essential for maintaining mucus fluidity and absorption of nutrients, and protection against chemical-induced oxidant injury. Within intestinal cells, these redox couples preserve an environment that supports physiological processes and orchestrates networks of enzymatic reactions against oxidative stress. In this review, we focus on the intestinal redox and antioxidant systems, their subcellular compartmentation, redox signaling and epithelial turnover, and contribution of luminal microbiota, key aspects that are relevant to understanding redox-dependent processes in gut biology with implications for degenerative digestive disorders, such as inflammation and cancer. PMID:21831010

Thiol peroxidase deficiency leads to increased mutational load and decreased fitness in Saccharomyces cerevisiae.

PubMed

Kaya, Alaattin; Lobanov, Alexei V; Gerashchenko, Maxim V; Koren, Amnon; Fomenko, Dmitri E; Koc, Ahmet; Gladyshev, Vadim N

2014-11-01

Thiol peroxidases are critical enzymes in the redox control of cellular processes that function by reducing low levels of hydroperoxides and regulating redox signaling. These proteins were also shown to regulate genome stability, but how their dysfunction affects the actual mutations in the genome is not known. Saccharomyces cerevisiae has eight thiol peroxidases of glutathione peroxidase and peroxiredoxin families, and the mutant lacking all these genes (∆8) is viable. In this study, we employed two independent ∆8 isolates to analyze the genome-wide mutation spectrum that results from deficiency in these enzymes. Deletion of these genes was accompanied by a dramatic increase in point mutations, many of which clustered in close proximity and scattered throughout the genome, suggesting strong mutational bias. We further subjected multiple lines of wild-type and ∆8 cells to long-term mutation accumulation, followed by genome sequencing and phenotypic characterization. ∆8 lines showed a significant increase in nonrecurrent point mutations and indels. The original ∆8 cells exhibited reduced growth rate and decreased life span, which were further reduced in all ∆8 mutation accumulation lines. Although the mutation spectrum of the two independent isolates was different, similar patterns of gene expression were observed, suggesting the direct contribution of thiol peroxidases to the observed phenotypes. Expression of a single thiol peroxidase could partially restore the growth phenotype of ∆8 cells. This study shows how deficiency in nonessential, yet critical and conserved oxidoreductase function, leads to increased mutational load and decreased fitness. Copyright © 2014 by the Genetics Society of America.

Lipogels: surface-adherent composite hydrogels assembled from poly(vinyl alcohol) and liposomes

NASA Astrophysics Data System (ADS)

Jensen, Bettina E. B.; Hosta-Rigau, Leticia; Spycher, Philipp R.; Reimhult, Erik; Städler, Brigitte; Zelikin, Alexander N.

2013-07-01

Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications.Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications. Electronic supplementary information (ESI) available: Paclitaxel calibration curve and images of DIC of PLL blended PVA physical hydrogels, lipogel FRAP, and different cell lines attached to lipogels are available. See DOI: 10.1039/c3nr01662e

Characterization of thiol-conjugated metabolites of ginger components shogaols in mouse and human urine and modulation of the glutathione levels in cancer cells by [6]-shogaol.

PubMed

Chen, Huadong; Soroka, Dominique N; Hu, Yuhui; Chen, Xiaoxin; Sang, Shengmin

2013-03-01

Shogaols, a series of major constituents in dried ginger with the most abundant being [6]-, [8]-, and [10]-shogaols, show much higher anticancer potencies than gingerols. Previously, we reported the mercapturic acid pathway as a major metabolic route for [6]-shogaol in mice. However, it is still unclear how the side chain length affects the metabolism of shogaols and how shogaols are metabolized in humans. We first investigate the metabolism of [10]-shogaol in mouse urine, and then investigate the biotransformation of shogaols in human urine. Our results show that eight major thiol-conjugated metabolites of [10]-shogaol were detected in mouse urine, while six major thiol-conjugated metabolites of [6]-shogaol, two thiol-conjugated metabolites of [8]-shogaol, and two thiol-conjugated metabolites of [10]-shogaol were detected in urine collected from human after drinking ginger tea, using LC/ESI-MS/MS. Our results clearly indicate the mercapturic acid pathway is a major metabolic route for [10]-shogaol in mice and for shogaols in human. Furthermore, we also investigated the regulation of glutathione (GSH) by [6]-shogaol in human colon cancer cells HCT-116. Our results show [6]-shogaol, after initially depleting glutathione levels, can subsequently restore and increase GSH levels over time. Shogaols are metabolized extensively in mouse and human to form thiol-conjugated metabolites and GSH might play an important role in the cancer-preventive activity of ginger. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of thiol-conjugated metabolites of ginger components shogaols in mouse and human rrine and modulation of the glutathione levels in cancer cells by [6]-shogaol

PubMed Central

Chen, Huadong; Soroka, Dominique N.; Hu, Yuhui; Chen, Xiaoxin; Sang, Shengmin

2013-01-01

Scope Shogaols, a series of major constituents in dried ginger with the most abundant being [6]-, [8]-, and [10]-shogaols, show much higher anti-cancer potencies than gingerols. Previously, we reported the mercapturic acid pathway as a major metabolic route for [6]-shogaol in mice. However, it is still unclear how the side chain length affects the metabolism of shogaols and how shogaols are metabolized in humans. Methods and results We first investigate the metabolism of [10]-shogaol in mouse urine, and then investigate the biotransformation of shogaols in human urine. Our results show that eight major thiol-conjugated metabolites of [10]-shogaol were detected in mouse urine, while six major thiol-conjugated metabolites of [6]-shogaol, two thiol-conjugated metabolites of [8]-shogaol, and two thiol-conjugated metabolites of [10]-shogaol were detected in urine collected from human after drinking ginger tea, using liquid chromatography/electrospray ionization tandem mass spectrometry. Our results clearly indicate the mercapturic acid pathway is a major metabolic route for [10]-shogaol in mice and for shogaols in human. Furthermore, we also investigated the regulation of glutathione (GSH) by [6]-shogaol in human colon cancer cells HCT-116. Our results show [6]-shogaol, after initially depleting glutathione levels, can subsequently restore and increase GSH levels over time. Conclusion Shogaols are metabolized extensively in mouse and human to form thiol-conjugated metabolites and GSH might play an important role in the cancer preventative activity of ginger. PMID:23322393

Mechanical Characterization of Polydopamine-Assisted Silver Deposition on Polymer Substrates

NASA Astrophysics Data System (ADS)

Cordes, Amanda Laurence

Inspired by the adhesive proteins in marine mussels, polydopamine has become a popular adhesive ad-layer for surface functionalization of a variety of substrates. Based on the chemistry of the dopamine monomer, amine and thiol functional groups are hypothesized to increase adhesion between polymer substrates and polydopamine thin films. This hypothesis was the central motivation for development of a tailorable thiol-ene system in order to study the effects of substrate chemistry on polydopamine adhesion. While polydopamine-adhered silver has been studied on a variety of substrates, no in depth mechanical characterization has been performed and to date, no research has been published on thiol-enes coated in polydopamine-adhered silver. The purpose of this study was to characterize the mechanical durability and adhesion properties of a polydopamine-adhered silver film on commercial substrates and a tailorable thiol-ene system. Polydopamine and silver coatings were deposited on a variety of polymer substrates through a simple dip-coat process. The polydopamine forms a thin uniform adhesive layer and the silver deposits in a discontinuous manner with a nanoparticle sized base layer covering the full surface and micron-sized clusters adhered sporadically on top. Mechanical tensile testing was performed to characterize the durability of the silver coating on commercial polymers. Coated nylon and HDPE showed no signs of degradation or delamination of the polydopamine-adhered silver coating up to 30% strain although both substrates showed large plastic deformation. Peel tests were performed on both commercial polymers as well as a tailorable thiol-ene system. Results support the hypothesis that polydopamine adhesion is increased with the presence of functional groups. Parts of the HDPE sample were cleanly peeled, but silver patches were left sporadically across the surface pointing to weaker adhesion between polyethylene and polydopamine. A high adhesive strength tape was used on nylon and the thiol-ene polymers and removed some of the large clusters but was ineffective at removing the particle base layer. The silver base layer remained firmly attached on the surface after multiple rounds of peel testing. With the addition of functional groups in the polymer makeup, the adhesion strength of polydopamine-adhered silver coatings can be increased to create a mechanically durable and adhesively robust silver coating.

Short communication: characterization of soluble thiols in bovine milk.

PubMed

Niero, G; De Marchi, M; Masi, A; Penasa, M; Cassandro, M

2015-09-01

Antioxidants are molecules essential for the maintenance of cell homeostasis and their intake through the diet has positive effects on human health. Among antioxidants, low-molecular-weight (LMW) thiols represent an important class of compounds. The aim of this study was to identify LMW thiols in bovine milk. A total of 96 individual milk samples from Brown Swiss, Holstein-Friesian, Alpine Grey, and Simmental cattle breeds were collected in 8 herds. The LMW thiols were extracted from the soluble fraction of milk and, following a derivatization protocol, they were separated by reverse phase HPLC and detected fluorimetrically. Six thiol species were detected and 2, glutathione (GSH) and cysteine-glycine (Cys-Gly), were identified and quantified. Regardless of the breed, the average concentration of Cys-Gly in milk was greater than that of GSH. Overall, milk from dual-purpose breeds (Simmental and Alpine Grey) was richer in LMW thiols than milk from dairy cows (Holstein-Friesian and Brown Swiss). Glutathione and Cys-Gly, closely linked metabolically, were strongly correlated. Pearson correlations of Cys-Gly with protein and casein contents were moderately low, and no relationship was found between GSH and milk chemical composition. Future research should focus on the identification of all detected LMW thiol species. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Oxidative stress, thiols, and redox profiles.

PubMed

Harris, Craig; Hansen, Jason M

2012-01-01

Oxidative stress has been recognized as a contributing factor in the toxicity of a large number of developmental toxicants. Traditional definitions of oxidative stress state that a shift in the balance between reduced and oxidized biomolecules within cells, in favor of the latter, result in changes that are deleterious to vital cell functions and can culminate in malformations and death. The glutathione (GSH)/glutathione disulfide (GSSG) redox couple has been the traditional marker of choice for characterization of oxidative stress because of its high concentrations and direct roles as antioxidant and cellular protectant. Steady state depletion of GSH through conjugation, oxidation, or export has often been reported as the sole criteria for invoking oxidative stress and a myriad of associated deleterious consequences. Numerous other, mostly qualitative, observations have also been reported to suggest oxidative stress has occurred but it is not always clear how well they reflect the state of a cell or its functions. Our emerging understanding of redox signaling and the roles of reactive oxygen species (ROS), thiols, oxidant molecules, and cellular antioxidants, all acting as second messengers, has prompted a redefinition of oxidative stress based on changes in the real posttranslational protein thiol modifications that are central to redox regulation and control. Thiol-based redox couples such as GSH/GSSG, cysteine/cystine (cys/cySS), thioredoxin-reduced/thioredoxin-oxidized (TRX(red)/TRX(ox)) form independent signaling nodes that selectively regulate developmental events and are closely linked to changes in intracellular redox potentials. Accurate assessment of the consequences of increased free radicals in developing conceptuses should best be made using a battery of measurements including the quantitative assessment of intracellular redox potential, ROS, redox status of biomolecules, and induced changes in specific redox signaling nodes. Methods are presented for a determination of ROS production, soluble thiol oxidation, redox potential, and a proteomic approach to evaluate the thiol oxidation state of specific proteins.

Enhanced cellular uptake of maleimide-modified liposomes via thiol-mediated transport

PubMed Central

Li, Tianshu; Takeoka, Shinji

2014-01-01

With a small amount of maleimide modification on the liposome surface, enhanced cellular uptake of liposomes and drug-delivery efficiency can be obtained both in vitro and in vivo. Herein, we describe the mechanisms underlying this enhanced cellular uptake. Suppression of the cellular uptake of maleimide-modified liposomes (M-GGLG, composed of 1,5-dihexadecyl N,N-diglutamyl-lysyl-L-glutamate [GGLG]/cholesterol/poly(ethylene glycol) – 1,2-distearoyl-sn-glycero-3-phosphoethanolamine [PEG5000-DSPE]/maleimide [M]-PEG5000-Glu2C18 at a molar ratio of 5:5:0.03:0.03) caused by temperature block and addition of serum was alleviated compared with that of liposomes without maleimide modification (GGLG liposomes, composed of GGLG/cholesterol/PEG5000-DSPE/PEG5000-Glu2C18 at a molar ratio of 5:5:0.03:0.03). When 0.01 nM N-ethylmaleimide was used to pre-block cellular thiols, the cellular uptake of M-GGLG liposomes was decreased to approximately 70% in HeLa, HCC1954, MDA-MB-468, and COS-7 cell lines. Moreover, inhibition of a thiol-related reductase such as protein disulfide isomerase resulted in a 15%–45% inhibition of the cellular uptake of M-GGLG liposomes, whereas GGLG liposomes were not influenced. Further, single and mixed inhibitors of clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis did not efficiently inhibit the cellular uptake of M-GGLG liposomes. Using confocal microscopy, we verified that M-GGLG liposomes were localized partially in lysosomes after inhibition of the mentioned conventional endocytic pathways. Therefore, it was hypothesized that the mechanisms underlying the enhanced cellular uptake of liposomes by maleimide modification was thiol-mediated membrane trafficking, including endocytosis and energy-independent transport. PMID:24940060

Enhanced cellular uptake of maleimide-modified liposomes via thiol-mediated transport.

PubMed

Li, Tianshu; Takeoka, Shinji

2014-01-01

With a small amount of maleimide modification on the liposome surface, enhanced cellular uptake of liposomes and drug-delivery efficiency can be obtained both in vitro and in vivo. Herein, we describe the mechanisms underlying this enhanced cellular uptake. Suppression of the cellular uptake of maleimide-modified liposomes (M-GGLG, composed of 1,5-dihexadecyl N,N-diglutamyl-lysyl-L-glutamate [GGLG]/cholesterol/poly(ethylene glycol) - 1,2-distearoyl-sn-glycero-3-phosphoethanolamine [PEG₅₀₀₀-DSPE]/maleimide [M]-PEG₅₀₀₀-Glu2C18 at a molar ratio of 5:5:0.03:0.03) caused by temperature block and addition of serum was alleviated compared with that of liposomes without maleimide modification (GGLG liposomes, composed of GGLG/cholesterol/PEG₅₀₀₀-DSPE/PEG₅₀₀₀-Glu2C₁₈ at a molar ratio of 5:5:0.03:0.03). When 0.01 nM N-ethylmaleimide was used to pre-block cellular thiols, the cellular uptake of M-GGLG liposomes was decreased to approximately 70% in HeLa, HCC1954, MDA-MB-468, and COS-7 cell lines. Moreover, inhibition of a thiol-related reductase such as protein disulfide isomerase resulted in a 15%-45% inhibition of the cellular uptake of M-GGLG liposomes, whereas GGLG liposomes were not influenced. Further, single and mixed inhibitors of clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis did not efficiently inhibit the cellular uptake of M-GGLG liposomes. Using confocal microscopy, we verified that M-GGLG liposomes were localized partially in lysosomes after inhibition of the mentioned conventional endocytic pathways. Therefore, it was hypothesized that the mechanisms underlying the enhanced cellular uptake of liposomes by maleimide modification was thiol-mediated membrane trafficking, including endocytosis and energy-independent transport.

Neutrophil-generated HOCl leads to non-specific thiol oxidation in phagocytized bacteria

PubMed Central

Degrossoli, Adriana; Müller, Alexandra; Xie, Kaibo; Schneider, Jannis F; Bader, Verian; Winklhofer, Konstanze F; Meyer, Andreas J

2018-01-01

Phagocytic immune cells kill pathogens in the phagolysosomal compartment with a cocktail of antimicrobial agents. Chief among them are reactive species produced in the so-called oxidative burst. Here, we show that bacteria exposed to a neutrophil-like cell line experience a rapid and massive oxidation of cytosolic thiols. Using roGFP2-based fusion probes, we could show that this massive breakdown of the thiol redox homeostasis was dependent on phagocytosis, presence of NADPH oxidase and ultimately myeloperoxidase. Interestingly, the redox-mediated fluorescence change in bacteria expressing a glutathione-specific Grx1-roGFP2 fusion protein or an unfused roGFP2 showed highly similar reaction kinetics to the ones observed with roGFP2-Orp1, under all conditions tested. We recently observed such an indiscriminate oxidation of roGFP2-based fusion probes by HOCl with fast kinetics in vitro. In line with these observations, abating HOCl production in immune cells with a myeloperoxidase inhibitor significantly attenuated the oxidation of all three probes in bacteria. PMID:29506649

Molecular cloning and characterization of Bacillus alvei thiol-dependent cytolytic toxin expressed in Escherichia coli.

PubMed

Geoffroy, C; Alouf, J E

1988-07-01

A chromosomal DNA fragment from Bacillus alvei, encoding a thiol-dependent haemolytic product known as alveolysin (Mr 60,000, pI 5.0) was cloned in Escherichia coli SK1592, using pBR322 as the vector plasmid. Only a single haemolysin-positive clone was identified, by testing for haemolysis on blood agar plates. The haemolytic material was associated with the host bacterial cell. It was released by ultrasonic disruption and purified 267-fold. A 64 kDa polypeptide of pI 8.2 cofractionated with haemolytic activity during gel filtration chromatography and isoelectric focusing. It behaved identically to alveolysin in its activation by thiols, inactivation by thiol group reagents, inhibition by cholesterol, and neutralization, immunoprecipitation and immunoblotting by immune sera raised against alveolysin and streptolysin O.

Iron and thiols as two major players in carcinogenesis: friends or foes?

PubMed

Toyokuni, Shinya

2014-01-01

Iron is the most abundant metal in the human body and mainly works as a cofactor for proteins such as hemoglobin and various enzymes. No independent life forms on earth can survive without iron. However, excess iron is intimately associated with carcinogenesis by increasing oxidative stress via its catalytic activity to generate hydroxyl radicals. Biomolecules with redox-active sulfhydryl function(s) (thiol compounds) are necessary for the maintenance of mildly reductive cellular environments to counteract oxidative stress, and for the execution of redox reactions for metabolism and detoxification. Involvement of glutathione S-transferase and thioredoxin has long attracted the attention of cancer researchers. Here, I update recent findings on the involvement of iron and thiol compounds during carcinogenesis and in cancer cells. It is now recognized that the cystine/glutamate transporter (antiporter) is intimately associated with ferroptosis, an iron-dependent, non-apoptotic form of cell death, observed in cancer cells, and also with cancer stem cells; the former with transporter blockage but the latter with its stabilization. Excess iron in the presence of oxygen appears the most common known mutagen. Ironically, the persistent activation of antioxidant systems via genetic alterations in Nrf2 and Keap1 also contributes to carcinogenesis. Therefore, it is difficult to conclude the role of iron and thiol compounds as friends or foes, which depends on the quantity/distribution and induction/flexibility, respectively. Avoiding further mutation would be the most helpful strategy for cancer prevention, and myriad of efforts are being made to sort out the weaknesses of cancer cells.

Strategies for Cd accumulation in Dittrichia viscosa (L.) Greuter: role of the cell wall, non-protein thiols and organic acids.

PubMed

Fernández, R; Fernández-Fuego, D; Bertrand, A; González, A

2014-05-01

Dittrichia viscosa (L.) Greuter is plant species commonly found in degraded zones of Asturias (Spain), where it accumulates high levels of Cd, but the mechanisms involved in this response in non-model plants have not been elucidated. In this way, we analysed the fraction of the total Cd bound to the cell walls, the ultrastructural localization of this metal, and non-protein thiol and organic acid concentrations of two clones of D. viscosa: DV-A (from a metal-polluted soil) and DV-W (from a non-polluted area). After 10 days of hydroponic culture with Cd, fractionation and ultrastructural localisation studies showed that most of the Cd accumulated by D. viscosa was kept in the cell wall. The non-protein thiol content rose in D. viscosa with Cd exposure, especially in the non-metallicolous DV-W clone, and in both clones we found with Cd exposure a synthesis de novo of phytochelatins PC2 and PC3 in shoots and roots and also of other phytochelatin-related compounds, particularly in roots. Regarding organic acids, their concentration in both clones decreased in shoots after Cd treatment, but increased in roots, mainly due to changes in the citric acid concentration. Thus, retention of Cd in the cell wall seems to be the first strategy in response to metal entry in D. viscosa and once inside cells non-protein thiols and organic acids might also participate in Cd tolerance. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

An excited state intramolecular proton transfer dye based fluorescence turn-on probe for fast detection of thiols and its applications in bioimaging

NASA Astrophysics Data System (ADS)

Zhao, Yun; Xue, Yuanyuan; Li, Haoyang; Zhu, Ruitao; Ren, Yuehong; Shi, Qinghua; Wang, Song; Guo, Wei

2017-03-01

In this study, a new fluorescent probe 2-(2‧-hydroxy-5‧-N-maleimide phenyl)-benzothiazole (probe 1), was designed and synthesized by linking the excited state intramolecular proton transfer (ESIPT) fluorophore to the maleimide group for selective detection of thiols in aqueous solution. The fluorescence of probe 1 is strongly quenched by maleimide group through the photo-induced electron transfer (PET) mechanism, but after reaction with thiol, the fluorescence of ESIPT fluorophore is restored, affording a large Stokes shifts. Upon addition of cysteine (Cys), probe 1 exhibited a fast response time (complete within 30 s) and a high signal-to-noise ratio (up to 23-fold). It showed a high selectivity and excellent sensitivity to thiols over other relevant biological species, with a detection limit of 3.78 × 10- 8 M (S/N = 3). Moreover, the probe was successfully applied to the imaging of thiols in living cells.

Chemical modifications of Au/SiO2 template substrates for patterned biofunctional surfaces.

PubMed

Briand, Elisabeth; Humblot, Vincent; Landoulsi, Jessem; Petronis, Sarunas; Pradier, Claire-Marie; Kasemo, Bengt; Svedhem, Sofia

2011-01-18

The aim of this work was to create patterned surfaces for localized and specific biochemical recognition. For this purpose, we have developed a protocol for orthogonal and material-selective surface modifications of microfabricated patterned surfaces composed of SiO(2) areas (100 μm diameter) surrounded by Au. The SiO(2) spots were chemically modified by a sequence of reactions (silanization using an amine-terminated silane (APTES), followed by amine coupling of a biotin analogue and biospecific recognition) to achieve efficient immobilization of streptavidin in a functional form. The surrounding Au was rendered inert to protein adsorption by modification by HS(CH(2))(10)CONH(CH(2))(2)(OCH(2)CH(2))(7)OH (thiol-OEG). The surface modification protocol was developed by testing separately homogeneous SiO(2) and Au surfaces, to obtain the two following results: (i) SiO(2) surfaces which allowed the grafting of streptavidin, and subsequent immobilization of biotinylated antibodies, and (ii) Au surfaces showing almost no affinity for the same streptavidin and antibody solutions. The surface interactions were monitored by quartz crystal microbalance with dissipation monitoring (QCM-D), and chemical analyses were performed by polarization modulation-reflexion absorption infrared spectroscopy (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS) to assess the validity of the initial orthogonal assembly of APTES and thiol-OEG. Eventually, microscopy imaging of the modified Au/SiO(2) patterned substrates validated the specific binding of streptavidin on the SiO(2)/APTES areas, as well as the subsequent binding of biotinylated anti-rIgG and further detection of fluorescent rIgG on the functionalized SiO(2) areas. These results demonstrate a successful protocol for the preparation of patterned biofunctional surfaces, based on microfabricated Au/SiO(2) templates and supported by careful surface analysis. The strong immobilization of the biomolecules resulting from the described protocol is advantageous in particular for micropatterned substrates for cell-surface interactions.

Thiol-Ene functionalized siloxanes for use as elastomeric dental impression materials

PubMed Central

Cole, Megan A.; Jankousky, Katherine C.; Bowman, Christopher N.

2014-01-01

Objectives Thiol- and allyl-functionalized siloxane oligomers are synthesized and evaluated for use as a radical-mediated, rapid set elastomeric dental impression material. Thiol-ene siloxane formulations are crosslinked using a redox-initiated polymerization scheme, and the mechanical properties of the thiol-ene network are manipulated through the incorporation of varying degrees of plasticizer and kaolin filler. Formulations with medium and light body consistencies are further evaluated for their ability to accurately replicate features on both the gross and microscopic levels. We hypothesize that thiol-ene functionalized siloxane systems will exhibit faster setting times and greater detail reproduction than commercially available polyvinylsiloxane (PVS) materials of comparable consistencies. Methods Thiol-ene functionalized siloxane mixtures formulated with varying levels of redox initiators, plasticizer, and kaolin filler are made and evaluated for their polymerization speed (FTIR), consistency (ISO4823.9.2), and surface energy (goniometer). Feature replication is evaluated quantitatively by SEM. The Tg, storage modulus, and creep behavior are determined by DMA. Results Increasing redox initiation rate increases the polymerization rate but at high levels also limits working time. Combining 0.86 wt% oxidizing agent with up to 5 wt% plasticizer gave a working time of 3 min and a setting time of 2 min. The selected medium and light body thiol-ene formulations also achieved greater qualitative detail reproduction than the commercial material and reproduced micrometer patterns with 98% accuracy. Significance Improving detail reproduction and setting speed is a primary focus of dental impression material design and synthesis. Radical-mediated polymerizations, particularly thiol-ene reactions, are recognized for their speed, reduced shrinkage, and ‘click’ nature. PMID:24553250

Chromenoquinoline-based thiol probes: a study on the quencher position for controlling fluorescent Off-On characteristics.

PubMed

Kand, Dnyaneshwar; Kalle, Arunasree Marasanapalli; Talukdar, Pinaki

2013-02-13

The design, synthesis and thiol sensing ability of chromenoquinoline-based fluorescent probes 4, 5 and 6 and are reported here. The relative position of the maleimide moiety was varied along the chromenoquinoline fluorophore to decrease the background fluorescence. Lower background fluorescence in probes 4 and 6 was rationalized by the smaller k(r)/k(nr) values compared to that of probe 5. An intramolecular charge transfer (ICT) mechanism was proposed for quenching and the extent was dependent on the position of the maleimide quencher. Fluorescent Off-On characteristics were evaluated by theoretical calculations. All probes were selective only towards thiol containing amino acids. Thiol sensing by probes 4 and 6 were much better compared to 5. Probe 4 displayed a better fluorescence response for less hindered thiol (185-, 223- and 156-fold for Hcy, Cys and GSH, respectively), while for probe 6, a higher enhancement in fluorescence was observed with more hindered thiols (180-, 205- and 245-fold for Hcy, Cys and GSH, respectively). The better response to bulkier thiol, GSH by probe 6 was attributed to the steric crowding at the C-4 position and bulkiness of the GSH group which force the succinimide unit to be in a nearly orthogonal conformation. This spatial arrangement was important in reducing the fluorescence quenching ability of the succinimide moiety. The application of probes 4, 5 and 6 was demonstrated by naked eye detection thiols using a 96-well plate system as well as by live-cell imaging.

Protein disulfide isomerase a multifunctional protein with multiple physiological roles

NASA Astrophysics Data System (ADS)

Ali Khan, Hyder; Mutus, Bulent

2014-08-01

Protein disulfide isomerase (PDI), is a member of the thioredoxin superfamily of redox proteins. PDI has three catalytic activities including, thiol-disulfide oxireductase, disulfide isomerase and redox-dependent chaperone. Originally, PDI was identified in the lumen of the endoplasmic reticulum and subsequently detected at additional locations, such as cell surfaces and the cytosol. This review will provide an overview of the recent advances in relating the structural features of PDI to its multiple catalytic roles as well as its physiological and pathophysiological functions related to redox regulation and protein folding.

Endothelin-1 receptor antagonists regulate cell surface-associated protein disulfide isomerase in sickle cell disease.

PubMed

Prado, Gregory N; Romero, Jose R; Rivera, Alicia

2013-11-01

Increased endothelin-1 (ET-1) levels, disordered thiol protein status, and erythrocyte hydration status play important roles in sickle cell disease (SCD) through unresolved mechanisms. Protein disulfide isomerase (PDI) is an oxidoreductase that mediates thiol/disulfide interchange reactions. We provide evidence that PDI is present in human and mouse erythrocyte membranes and that selective blockade with monoclonal antibodies against PDI leads to reduced Gardos channel activity (1.6±0.03 to 0.56±0.02 mmol·10(13) cell(-1)·min(-1), P<0.001) and density of sickle erythrocytes (D50: 1.115±0.001 to 1.104±0.001 g/ml, P=0.012) with an IC50 of 4 ng/ml. We observed that erythrocyte associated-PDI activity was increased in the presence of ET-1 (3.1±0.2 to 5.6±0.4%, P<0.0001) through a mechanism that includes casein kinase II. Consistent with these results, in vivo treatment of BERK sickle transgenic mice with ET-1 receptor antagonists lowered circulating and erythrocyte associated-PDI activity (7.1±0.3 to 5.2±0.2%, P<0.0001) while improving hematological parameters and Gardos channel activity. Thus, our results suggest that PDI is a novel target in SCD that regulates erythrocyte volume and oxidative stress and may contribute to cellular adhesion and endothelial activation leading to vasoocclusion as observed in SCD.

The yeast Hsp70 Ssa1 is a sensor for activation of the heat shock response by thiol-reactive compounds

PubMed Central

Wang, Yanyu; Gibney, Patrick A.; West, James D.; Morano, Kevin A.

2012-01-01

The heat shock transcription factor HSF1 governs the response to heat shock, oxidative stresses, and xenobiotics through unknown mechanisms. We demonstrate that diverse thiol-reactive molecules potently activate budding yeast Hsf1. Hsf1 activation by thiol-reactive compounds is not consistent with the stresses of misfolding of cytoplasmic proteins or cytotoxicity. Instead, we demonstrate that the Hsp70 chaperone Ssa1, which represses Hsf1 in the absence of stress, is hypersensitive to modification by a thiol-reactive probe. Strikingly, mutation of two conserved cysteine residues to serine in Ssa1 rendered cells insensitive to Hsf1 activation and subsequently induced thermotolerance by thiol-reactive compounds, but not by heat shock. Conversely, substitution with the sulfinic acid mimic aspartic acid resulted in constitutive Hsf1 activation. Cysteine 303, located within the nucleotide-binding domain, was found to be modified in vivo by a model organic electrophile, demonstrating that Ssa1 is a direct target for thiol-reactive molecules through adduct formation. These findings demonstrate that Hsp70 is a proximal sensor for Hsf1-mediated cytoprotection and can discriminate between two distinct environmental stressors. PMID:22809627

A Central Role for Thiols in Plant Tolerance to Abiotic Stress

PubMed Central

Zagorchev, Lyuben; Seal, Charlotte E.; Kranner, Ilse; Odjakova, Mariela

2013-01-01

Abiotic stress poses major problems to agriculture and increasing efforts are being made to understand plant stress response and tolerance mechanisms and to develop new tools that underpin successful agriculture. However, the molecular mechanisms of plant stress tolerance are not fully understood, and the data available is incomplete and sometimes contradictory. Here, we review the significance of protein and non-protein thiol compounds in relation to plant tolerance of abiotic stress. First, the roles of the amino acids cysteine and methionine, are discussed, followed by an extensive discussion of the low-molecular-weight tripeptide, thiol glutathione, which plays a central part in plant stress response and oxidative signalling and of glutathione-related enzymes, including those involved in the biosynthesis of non-protein thiol compounds. Special attention is given to the glutathione redox state, to phytochelatins and to the role of glutathione in the regulation of the cell cycle. The protein thiol section focuses on glutaredoxins and thioredoxins, proteins with oxidoreductase activity, which are involved in protein glutathionylation. The review concludes with a brief overview of and future perspectives for the involvement of plant thiols in abiotic stress tolerance. PMID:23549272

Formation of mercury sulfide from Hg(II)−thiolate complexes in natural organic matter

USGS Publications Warehouse

Alain Manceau,; Cyprien Lemouchi,; Mironel Enescu,; Anne-Claire Gaillot,; Martine Lanson,; Valerie Magnin,; Pieter Glatzel,; Poulin, Brett; Ryan, Joseph N.; Aiken, George R.; Isabelle Gautier-Lunea,; Kathryn L. Nagy,

2015-01-01

Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, TN, in the United States. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified a chemical reaction mechanism that is thermodynamically favorable in which thiol-bound mercury polymerizes to mercury–sulfur clusters. The clusters form by elimination of sulfur from the thiol complexes via breaking of mercury–sulfur bonds as in an alkylation reaction. Addition of sulfide is not required. This nucleation mechanism provides one explanation for how mercury may be immobilized, and eventually sequestered, in oxygenated surface environments.

A novel high drug loading mussel-inspired polydopamine hybrid nanoparticle as a pH-sensitive vehicle for drug delivery.

PubMed

Hou, Jie; Guo, Chunlei; Shi, Yuzhi; Liu, Ergang; Dong, Weibing; Yu, Bo; Liu, Shiyuan; Gong, Junbo

2017-11-25

A novel high drug loading pH-cleavable polymer hybrid nanoparticle was prepared via doxorubicin (DOX) grafted onto PEGylated, mussel-inspired polydopamine (PDA) and then coated onto hollow silica nanoparticles for drug delivery. A series of characterization shed light on the formation mechanisms of PDA coatings on hollow silica. We hypothesized that dopamine was first absorbed onto the surface of hollow silica and then began self-polymerization. A Dox-containing thiol moiety was fabricated with conjugation between doxorubicin hydrochloride and Mercaptopropionyalkali with a pH-cleavable hydrozone bond. Using a Michael addition reaction, several Dox-containing thiol moieties were grafted onto the surface of the PDA. The drug loading capacity can reach 35.43%. It can minimize the metabolic problem of silica. The released behavior of Dox can be significantly enhanced at endosomal pH compared to physiological pH. After folate modification, nanoparticles can lead to more cellular endocytosis. Meanwhile animal assays showed that more Dox accumulated in tumor tissue, which can enhanced the cytotoxicity to 4T1 cancer cells with a targeting group compared to free DOX and untargeted groups. Meanwhile, the tumor growth was significantly inhibited. This promising material shows a promising future as a drug delivery system. Copyright © 2017 Elsevier B.V. All rights reserved.

Octadecyl Chains Immobilized onto Hyaluronic Acid Coatings by Thiol-ene "Click Chemistry" Increase the Surface Antimicrobial Properties and Prevent Platelet Adhesion and Activation to Polyurethane.

PubMed

Felgueiras, Helena P; Wang, L M; Ren, K F; Querido, M M; Jin, Q; Barbosa, M A; Ji, J; Martins, M C L

2017-03-08

Infection and thrombus formation are still the biggest challenges for the success of blood contact medical devices. This work aims the development of an antimicrobial and hemocompatible biomaterial coating through which selective binding of albumin (passivant protein) from the bloodstream is promoted and, thus, adsorption of other proteins responsible for bacterial adhesion and thrombus formation can be prevented. Polyurethane (PU) films were coated with hyaluronic acid, an antifouling agent, that was previously modified with thiol groups (HA-SH), using polydopamine as the binding agent. Octadecyl acrylate (C18) was used to attract albumin since it resembles the circulating free fatty acids and albumin is a fatty acid transporter. Thiol-ene "click chemistry" was explored for C18 immobilization on HA-SH through a covalent bond between the thiol groups from the HA and the alkene groups from the C18 chains. Surfaces were prepared with different C18 concentrations (0, 5, 10, and 20%) and successful immobilization was demonstrated by scanning electron microscopy (SEM), water contact angle determinations, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The ability of surfaces to bind albumin selectively was determined by quartz crystal microbalance with dissipation (QCM-D). Albumin adsorption increased in response to the hydrophobic nature of the surfaces, which augmented with C18 saturation. HA-SH coating reduced albumin adsorption to PU. C18 immobilized onto HA-SH at 5% promoted selective binding of albumin, decreased Staphylococcus aureus adhesion and prevented platelet adhesion and activation to PU in the presence of human plasma. C18/HA-SH coating was established as an innovative and promising strategy to improve the antimicrobial properties and hemocompatibility of any blood contact medical device.

Mechanistic understanding of the cysteine capping modifications of antibodies enables selective chemical engineering in live mammalian cells.

PubMed

Zhong, Xiaotian; He, Tao; Prashad, Amar S; Wang, Wenge; Cohen, Justin; Ferguson, Darren; Tam, Amy S; Sousa, Eric; Lin, Laura; Tchistiakova, Lioudmila; Gatto, Scott; D'Antona, Aaron; Luan, Yen-Tung; Ma, Weijun; Zollner, Richard; Zhou, Jing; Arve, Bo; Somers, Will; Kriz, Ronald

2017-04-20

Protein modifications by intricate cellular machineries often redesign the structure and function of existing proteins to impact biological networks. Disulfide bond formation between cysteine (Cys) pairs is one of the most common modifications found in extracellularly-destined proteins, key to maintaining protein structure. Unpaired surface cysteines on secreted mammalian proteins are also frequently found disulfide-bonded with free Cys or glutathione (GSH) in circulation or culture, the mechanism for which remains unknown. Here we report that these so-called Cys-capping modifications take place outside mammalian cells, not in the endoplasmic reticulum (ER) where oxidoreductase-mediated protein disulfide formation occurs. Unpaired surface cysteines of extracellularly-arrived proteins such as antibodies are uncapped upon secretion before undergoing disulfide exchange with cystine or oxidized GSH in culture medium. This observation has led to a feasible way to selectively modify the nucleophilic thiol side-chain of cell-surface or extracellular proteins in live mammalian cells, by applying electrophiles with a chemical handle directly into culture medium. These findings provide potentially an effective approach for improving therapeutic conjugates and probing biological systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct Nanoscale Conversion of Biomolecular Signals into Electronic Information

DTIC Science & Technology

2008-09-22

the electrode surface. In this experiment, the single free cysteine group featured in the GOx structure was exploited to demonstrate that orientation...first with GOx-ssDNA conjugates featuring a sequence complementary to the address strand, then with a non-complementary conjugate and finally with...fully-functional for an enzyme that features a free thiol group, or that can be engineered to incorporate a thiol onto its outer shell

Interfacial thiol-ene photoclick reactions for forming multilayer hydrogels.

PubMed

Shih, Han; Fraser, Andrew K; Lin, Chien-Chi

2013-03-13

Interfacial visible light-mediated thiol-ene photoclick reactions were developed for preparing step-growth hydrogels with multilayer structures. The effect of a noncleavage type photoinitiator eosin-Y on visible-light-mediated thiol-ene photopolymerization was first characterized using in situ photorheometry, gel fraction, and equilibrium swelling ratio. Next, spectrophotometric properties of eosin-Y in the presence of various relevant macromer species were evaluated using ultraviolet-visible light (UV-vis) spectrometry. It was determined that eosin-Y was able to reinitiate the thiol-ene photoclick reaction, even after light exposure. Because of its small molecular weight, most eosin-Y molecules readily leached out from the hydrogels. The diffusion of residual eosin-Y from preformed hydrogels was exploited for fabricating multilayer step-growth hydrogels. Interfacial hydrogel coating was formed via the same visible-light-mediated gelation mechanism without adding fresh initiator. The thickness of the thiol-ene gel coating could be easily controlled by adjusting visible light exposure time, eosin-Y concentration initially loaded in the core gel, or macromer concentration in the coating solution. The major benefits of this interfacial thiol-ene coating system include its simplicity and cytocompatibility. The formation of thiol-ene hydrogels and coatings neither requires nor generates any cytotoxic components. This new gelation chemistry may have great utilities in controlled release of multiple sensitive growth factors and encapsulation of multiple cell types for tissue regeneration.

Deficient expression of aldehyde dehydrogenase 1A1 is consistent with increased sensitivity of Gorlin syndrome patients to radiation carcinogenesis.

PubMed

Wright, Aaron T; Magnaldo, Thierry; Sontag, Ryan L; Anderson, Lindsey N; Sadler, Natalie C; Piehowski, Paul D; Gache, Yannick; Weber, Thomas J

2015-06-01

Human phenotypes that are highly susceptible to radiation carcinogenesis have been identified. Sensitive phenotypes often display robust regulation of molecular features that modify biological response, which can facilitate identification of the pathways/networks that contribute to pathophysiological outcomes. Here we interrogate primary dermal fibroblasts isolated from Gorlin syndrome patients (GDFs), who display a pronounced inducible tumorigenic response to radiation, in comparison to normal human dermal fibroblasts (NHDFs). Our approach exploits newly developed thiol reactive probes to define changes in protein thiol profiles in live cell studies, which minimizes artifacts associated with cell lysis. Redox probes revealed deficient expression of an apparent 55 kDa protein thiol in GDFs from independent Gorlin syndrome patients, compared with NHDFs. Proteomics tentatively identified this protein as aldehyde dehydrogenase 1A1 (ALDH1A1), a key enzyme regulating retinoic acid synthesis, and ALDH1A1 protein deficiency in GDFs was confirmed by Western blot. A number of additional protein thiol differences in GDFs were identified, including radiation responsive annexin family members and lamin A/C. Collectively, candidates identified in our study have plausible implications for radiation health effects and cancer susceptibility. © 2013 Wiley Periodicals, Inc.

Organelle Redox of CF and CFTR-Corrected Airway Epithelia

PubMed Central

Schwarzer, Christian; Illek, Beate; Suh, Jung H.; Remington, S. James; Fischer, Horst; Machen, Terry E.

2014-01-01

In cystic fibrosis reduced CFTR function may alter redox properties of airway epithelial cells. Redox-sensitive GFP (roGFP1) and imaging microscopy were used to measure redox potentials of cytosol, ER, mitochondria and cell surface of cystic fibrosis nasal epithelial cells and CFTR-corrected cells. We also measured glutathione and cysteine thiol redox states in cell lysates and apical fluids to provide coverage over a range of redox potentials and environments that might be affected by CFTR. As measured with roGFP1, redox potentials at the cell surface (~ -207 ±8 mV) and in the ER (~ -217 ±1 mV) and rates of regulation of the apical fluid and ER lumen following DTT treatment were similar for CF and CFTR-corrected cells. CF and CFTR-corrected cells had similar redox potentials in mitochondria (-344 ±9 mV) and cytosol (-322 ±7 mV). Oxidation of carboxy-dichlorodihydrofluoresceindiacetate and of apical Amplex Red occurred at equal rates in CF and CFTR-corrected cells. Glutathione and cysteine redox couples in cell lysates and apical fluid were equal in CF and CFTR-corrected cells. These quantitative estimates of organelle redox potentials combined with apical and cell measurements using small molecule couples confirmed there were no differences in redox properties of CF and CFTR-corrected cells. PMID:17603939

Ascorbyl stearate and ionizing radiation potentiate apoptosis through intracellular thiols and oxidative stress in murine T lymphoma cells.

PubMed

Mane, Shirish D; Kamatham, Akhilender Naidu

2018-02-01

Ascorbyl stearate (Asc-s) is a derivative of ascorbic acid with better anti-tumour efficacy compared to its parent compound ascorbic acid. In this study, we have examined radio-sensitizing effect of Asc-s in murine T cell lymphoma (EL4) cells at 4 Gy. Asc-s and radiation treatment reduced cell proliferation, induced apoptosis in a dose dependent manner by arresting the cells at S/G2-M phase of cell cycle. It also decreased the frequency of cancer stem cells per se, with significantly higher decrease in combination with radiation treatment./Further, Asc-s and radiation treatment increased the level of reactive oxygen species (ROS), drop in mitochondrial membrane potential (MMP) and increased caspase-3 activity resulting in apoptosis of EL4 cells. Further it also significantly decreased GSH/GSSG ratio due to binding of Asc-s with thiols. The increase in oxidative stress induced by Asc-s and radiation treatment was abrogated by thiol antioxidants in EL4 cells. Interestingly, this redox modulation triggered significant increase in protein glutathionylation in a time dependent manner. Asc-s treatment resulted in glutathionylation of IKK, p50-NF-kB and mutated p53, thereby inhibiting cancer progression during oxidative stress. Asc-s quenches GSH ensuing Asc-s + GSH adduct thereby further modulating GSH/GSSG ratio as evident from HPLC and docking studies. The anti-tumour effect of Asc-s along with radiation was studied by injecting EL4 cells in synegenicC57/BL6 male mice. Intraperitoneal injection of Asc-s followed by radiation exposure at 4 Gy to the tumour bearing mice resulted in radio-sensitization which is evident from significant regression of tumour as evident from tumour burden index. The survival study supports the data that Asc-s pre-treatment enhances radio-sensitization in murine lymphoma. Our data, suggest that Asc-s and ionizing radiation induced cell cycle arrest and apoptosis by perturbing redox balance through irreversible complexes of thiols with Asc-s, disturbed mitochondrial membrane permeability and activation of caspase-3 in EL4 cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Thiol dependent NF-κB suppression and inhibition of T-cell mediated adaptive immune responses by a naturally occurring steroidal lactone Withaferin A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gambhir, Lokesh; Checker, Rahul; Sharma, Deepak

Withaferin A (WA), a steroidal lactone isolated from ayurvedic medicinal plant Withania somnifera, was shown to inhibit tumor growth by inducing oxidative stress and suppressing NF-κB pathway. However, its effect on T-cell mediated adaptive immune responses and the underlying mechanism has not been investigated. Since both T-cell responses and NF-κB pathway are known to be redox sensitive, the present study was undertaken to elucidate the effect of WA on adaptive immune responses in vitro and in vivo. WA inhibited mitogen induced T-cell and B-cell proliferation in vitro without inducing any cell death. It inhibited upregulation of T-cell (CD25, CD69, CD71more » and CD54) and B-cell (CD80, CD86 and MHC-II) activation markers and secretion of Th1 and Th2 cytokines. WA induced oxidative stress by increasing the basal ROS levels and the immunosuppressive effects of WA were abrogated only by thiol anti-oxidants. The redox modulatory effects of WA in T-cells were attributed to its ability to directly interact with free thiols. WA inhibited NF-κB nuclear translocation in lymphocytes and prevented the direct binding of nuclear NF-κB to its consensus sequence. MALDI-TOF analysis using a synthetic NF-κB-p50 peptide containing Cys-62 residue suggested that WA can modify the cysteine residue of NF-κB. The pharmacokinetic studies for WA were also carried out and in vivo efficacy of WA was studied using mouse model of Graft-versus-host disease. In conclusion, WA is a potent inhibitor of T-cell responses and acts via a novel thiol dependent mechanism and inhibition of NF-κB pathway. - Highlights:: • Withaferin A (WA) inhibited T-cell and B-cell mediated immune responses. • WA increased basal ROS levels in lymphocytes. • WA directly interacted with GSH as studied using spectrophotometry and HPLC. • WA inhibited NF-κB nuclear translocation and binding of nuclear NF-κB to DNA. • WA inhibited induction of the graft-versus-host disease in mice.« less

Hydrolysis-controlled protein adsorption and antifouling behaviors of mixed charged self-assembled monolayer: A molecular simulation study.

PubMed

Liu, Jie; Zhou, Jian

2016-08-01

Understanding the mechanism of the antimicrobial and antifouling properties of mixed charged materials is of great significance. The interactions between human gamma fibrinogen (γFg) and mixed carboxylic methyl ether-terminated (COOCH3-) and trimethylamino-terminated (N(CH3)3(+)-) SAMs and the influence of hydrolysis were studied by molecular simulations. After hydrolysis, the mixed SAMs exhibit behaviors from antimicrobial to antifouling, since the COOCH3-thiols were translated into carboxylic acid (COO(-)-) terminated thiols, which carried a net charge of -1 e. Simulation results showed that the main differences between COOCH3-/N(CH3)3(+)-SAM and COO(-)-/N(CH3)3(+)-SAM are the charged property and the hydration layer above the surface. γFg could stably adsorb on the positively-charged COOCH3-/N(CH3)3(+)-SAM. The adsorption behavior is mainly induced by the strong electrostatic attraction. There is a single hydration layer bound to the surface, which is related to the N(CH3)3(+) groups. The van der Waals repulsion between γFg and the single hydration layer are not strong enough to compensate the strong electrostatic attraction. After hydrolysis, the positively-charged SAM was transferred to a neutral mixed charged surface, the electrostatic attraction between γFg and the surface disappears. Meanwhile, the SAM surface is covered by double hydration layers, which is induced by the N(CH3)3(+) and COO(-) groups; water molecules around COO(-) groups are obviously denser than that around N(CH3)3(+) groups. With the combined contribution from double hydration layers and the vanishment of electrostatic attraction, γFg is forced to desorb from the surface. After hydrolysis, the internal structure of mixed SAM appears more ordered due to the electrostatic interactions between charged groups on the top of SAMs. The antimicrobial and antifouling materials are of great importance in many biological applications. The strong hydration property of surfaces and the interactions between proteins and surfaces play a key role in resisting protein adsorption. The mixed SAMs, constructed from a 1:1 combination of COOCH3- and N(CH3)3(+)-terminated thiols, can induce protein adsorption mainly through the electrostatic interaction. When the COOCH3-terminated thiols were hydrolyzed to negatively charged COO(-)-terminated thiols, the mixed-charged SAMs switched from antimicrobial to antifouling. Due to the strong hydration property of the mixed charged SAMs, the adsorbed γFg moved away from the surface. Understanding the interactions between protein and mixed-charged SAMs in the atomistic level is important for the practical design and development of new antimicrobial and antifouling materials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Differential reactivity of maleimide and bromoacetyl functions with thiols: application to the preparation of liposomal diepitope constructs.

PubMed

Schelté, P; Boeckler, C; Frisch, B; Schuber, F

2000-01-01

The comparative reactivity of maleimide and bromoacetyl groups with thiols (2-mercaptoethanol, free cysteine, and cysteine residues present at the N-terminus of peptides) was investigated in aqueous media. These studies were performed (i) with water-soluble functionalized model molecules, i.e., polyoxyethylene-based spacer arms that could also be coupled to lipophilic anchors destined to be incorporated into liposomes, and (ii) with small unilamellar liposomes carrying at their surface these thiol-reactive functions. Our results indicate that an important kinetic discrimination (2-3 orders of magnitude in terms of rate constants) can be achieved between the maleimide and bromoacetyl functions when the reactions with thiols are performed at pH 6.5. The bromoacetyl function which reacts at higher pH values (e.g., pH 9.0) retained a high chemoselectivity; i.e., under conditions where it reacted appreciably with the thiols of, e.g., HS-peptides, it did react with other nucleophilic functions such as alpha- and epsilon-amino groups or imidazole, which could also be present in peptides. This differential reactivity was applied to design chemically defined and highly immunogenic liposomal diepitope constructs as synthetic vaccines, i.e., vesicles carrying at their surface two different peptides conjugated each to a specific amphiphilic anchor. This was realized by coupling sequentially at pH 6.5 and 9.0 two HS-peptides to preformed vesicles containing lipophilic anchors functionalized with maleimide and bromoacetyl groups [Boeckler, C., et al. (1999) Eur. J. Immunol. 29, 2297-2308].

Oligolysine-based saccharide clusters: synthesis and specificity.

PubMed Central

Frison, Natacha; Marceau, Philippe; Roche, Annie-Claude; Monsigny, Michel; Mayer, Roger

2002-01-01

In search of specific and highly selective sugar clusters for cell receptors, such as membrane lectins, various disaccharides were coupled to small peptide cores through an amide bond. In a first step, the reducing disaccharides, i.e. lactose and three different dimannoses, were converted into glycosyl-pyroglutamyl-beta-alanine derivatives. The free carboxylic group of these conjugates was then coupled to the alpha and epsilon amino groups of the core peptide (Lys( n )-Ala-Cys-NH2) with n =1 to 5, with complete substitution leading to homogeneous glycoclusters. The thiol group of the cysteine residue was used to tag the glycosylated oligolysines upon reaction with fluorescein iodoacetamide. The affinity of these glycoclusters towards two plant lectins was assessed by surface plasmon resonance. The selectivity of their cell uptake was investigated by flow cytometry using two types of cells: a human hepatoma cell line (HepG2 cells) expressing the plasma membrane galactose-specific lectin, and monocyte-derived dendritic cells expressing the plasma membrane mannose-specific lectin. The glycoclusters containing four or five disaccharides were shown to bind plant lectins and cell surface membrane lectins with a narrow selectivity and with a high affinity. PMID:12119048

Induction of apoptosis in human T-cells by methyl mercury: temporal relationship between mitochondrial dysfunction and loss of reductive reserve.

PubMed

Shenker, B J; Guo, T L; O, I; Shapiro, I M

1999-05-15

The objective of our study was to define the mechanism by which MeHgCl induces human T-cell apoptosis. We asked the question: does mercury disrupt the Deltapsim and induce a mitochondrial permeability transition state? Using two fluorescent reagents, JC-1 and DiOC6(3), we demonstrated that MeHgCl exposure resulted in a decrease in the Deltapsim. Since a decline in Deltapsim can disturb the pHi, we employed SNARF-1 to assess pHi; results indicate that mercury treatment reduced the pHi from 7.0 to 6.5. Consistent with these observations, we noted that uncoupled electron transfer reactions generated ROS, while cardiolipin, a mitochondrial phospholipid, was oxidized. In concert with the biochemical changes, there was a decrease in overall dimension of the mitochondria of mercury-treated cells and a loss in cristae architecture. The toxicant also depleted the thiol reserves of the cell and promoted translocation of cytochrome c from the mitochondria to the cytosol. Furthermore, when T cells were thiol-depleted, there was increased susceptibility to MeHgCl-induced apoptosis. Finally, we established a temporal relationship between the decline in Deltapsim, generation of ROS, and depletion of thiol reserves. The earliest detectable event was at the level of the mitochondrion; in the presence of MeHgCl there was a profound reduction in mitochondrial Deltapsim and a decline in GSH levels within 1 h. Subsequently, a further decrease in thiol reserves was linked to the generation of ROS. We propose that the target organelle for MeHgCl is the mitochondrion and that induction of oxidative stress leads to activation of death-signaling pathways. Copyright 1999 Academic Press.

Using the Localized Surface Plasmon Resonance of Gold Nanoparticles to Monitor Lipid Membrane Assembly and Protein Binding.

PubMed

Messersmith, Reid E; Nusz, Greg J; Reed, Scott M

2013-12-19

Gold nanoparticles provide a template for preparing supported lipid layers with well-defined curvature. Here, we utilize the localized surface plasmon resonance (LSPR) of gold nanoparticles as a sensor for monitoring the preparation of lipid layers on nanoparticles. The LSPR is very sensitive to the immediate surroundings of the nanoparticle surface and it is used to monitor the coating of lipids and subsequent conversion of a supported bilayer to a hybrid membrane with an outer lipid leaflet and an inner leaflet containing hydrophobic alkanethiol. We demonstrate that both decanethiol and propanethiol are able to form hybrid membranes and that the membrane created over the shorter thiol can be stripped from the gold along with the lipid leaflet using β-mercaptoethanol. The sensitivity of the nanoparticle LSPR to the refractive index (RI) of its surroundings is greater when the shorter thiol is used (37.8 ± 1.5 nm per RI unit) than when the longer thiol is used (27.5 ± 0.5 nm per RI unit). Finally, C-reactive protein binding to the membrane is measured using this sensor allowing observation of both protein-membrane and nanoparticle-nanoparticle interactions without chemical labeling of protein or lipids.

Synthesis, Characterization and Cytotoxicity Evaluation of Nitric Oxide-Iron Oxide magnetic Nanoparticles

NASA Astrophysics Data System (ADS)

Haddad, P. S.; Britos, T. N.; Santos, M. C.; Seabra, A. B.; Palladino, M. V.; Justo, G. Z.

2015-05-01

The present work is focused on the synthesis, characterization and cytotoxic evaluation of superparamagnetic iron oxide nanoparticles (SPIONs). SPIONs have been proposed for an increasing number of biomedical applications, such as drug-delivery. To this end, toxicological studies of their potential effects in biological systems must be better evaluated. The aim of this study was to examine the in vitro cytotoxicity of thiolated (SH) and S-nitrosated (S-NO) SPIONs in cancer cell lines. SPIONs were prepared by the coprecipitation method using ferrous and ferric chlorides in aqueous solution. The nanoparticles (Fe3O4) were coated with thiol containing molecule cysteine (Cys) (molar ratio SPIONs:ligand = 1:20), leading to the formation of an aqueous dispersion of thiolated nanoparticles (SH- SPIONs). These particles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results obtained showed that Cys-SPIONs have a mean diameter of 14 nm at solid state and present super paramagnetic behavior at room temperature. Thiol groups on the surface of the nanoparticles were nitrosated through the addition of sodium nitrite leading to the formation of S-NOCys-SPIONs (S-nitrosated-Cys-SPIONs), which act as spontaneous nitric oxide (NO) donor). The cytotoxicity of thiolated and S-nitrosated nanoparticles was evaluated in acute T cell leukemia (Jurkat cell line) and Lewis lung carcinoma (3LL) cells. The results showed that at low concentrations thiolated (Cys) and S- nitrosated (S-NOCyst) SPIONs display low cytotoxicity in both cell types. However, at higher concentrations, Cys-SPIONs exhibited cytotoxic effects, whereas S-NOCys-SPIONs protected them, and also promoted cell proliferation.

Withaferin A induces apoptosis through the generation of thiol oxidation in human head and neck cancer cells.

PubMed

Park, Jong Won; Min, Kyoung-Jin; Kim, Dong Eun; Kwon, Taeg Kyu

2015-01-01

Withaferin A is a steroidal lactone purified from the Indian medicinal plant, Withania somnifera. Withaferin A has been shown to inhibit the proliferation, metastasis, invasion and angiogenesis of cancer cells. In the present study, we investigated whether withaferin A induces apoptosis in the human head and neck cancer cells, AMC-HN4. Withaferin A markedly increased the sub-G1 cell population and the cleavage of poly(ADP-ribose) polymerase (PARP), which are markers of apoptosis. Pan-caspase inhibitor, z-VAD-fmk (z-VAD), markedly inhibited the withaferin A-induced apoptosis. However, the withaferin A-induced increase in the expression of COX-2 was not affected by treatment with z-VAD. Furthermore, withaferin A upregulated cyclooxygenase-2 (COX-2) expression. The COX-2 inhibitor, NS-398, reduced the withaferin A-induced production of prostaglandin E2. However, treatment with NS-398 did not affect the sub-G1 population and the cleavage of PARP. In addition, the withaferin A-induced apoptosis was independent of reactive oxygen species production. Thiol donors [N-acetylcysteine (NAC) and dithiothreitol (DTT)] reversed withaferin A-induced apoptosis. Therefore, our data suggest that withaferin A induces apoptosis through the mechanism of thiol oxidation in head and neck carcinoma cells.

Nanostructure-Directed Chemical Sensing: The IHSAB Principle and the Effect of Nitrogen and Sulfur Functionalization on Metal Oxide Decorated Interface Response

PubMed Central

Laminack, William I.; Gole, James L.

2013-01-01

The response matrix, as metal oxide nanostructure decorated n-type semiconductor interfaces are modified in situ through direct amination and through treatment with organic sulfides and thiols, is demonstrated. Nanostructured TiO2, SnOx, NiO and CuxO (x = 1,2), in order of decreasing Lewis acidity, are deposited to a porous silicon interface to direct a dominant electron transduction process for reversible chemical sensing in the absence of significant chemical bond formation. The metal oxide sensing sites can be modified to decrease their Lewis acidity in a process appearing to substitute nitrogen or sulfur, providing a weak interaction to form the oxynitrides and oxysulfides. Treatment with triethylamine and diethyl sulfide decreases the Lewis acidity of the metal oxide sites. Treatment with acidic ethane thiol modifies the sensor response in an opposite sense, suggesting that there are thiol (SH) groups present on the surface that provide a Brønsted acidity to the surface. The in situ modification of the metal oxides deposited to the interface changes the reversible interaction with the analytes, NH3 and NO. The observed change for either the more basic oxynitrides or oxysulfides or the apparent Brønsted acid sites produced from the interaction of the thiols do not represent a simple increase in surface basicity or acidity, but appear to involve a change in molecular electronic structure, which is well explained using the recently developed inverse hard and soft acids and bases (IHSAB) model. PMID:28348345

Protective effects of anethole dithiolethione against oxidative stress-induced cytotoxicity in human Jurkat T cells.

PubMed

Khanna, S; Sen, C K; Roy, S; Christen, M O; Packer, L

1998-07-01

The protective effects of anethole dithiolethione (ADT) against H2O2- or 4-hydroxynonenal (HNE)-induced cytotoxicity in human Jurkat T cells were investigated. Jurkat T cells were pretreated with ADT (10-50 microM) for 18 hr and then challenged with H202 or HNE for up to 4 hr. Cytotoxicity was assessed by measuring: 1) leakage of lactate dehydrogenase from cells to medium; and 2) exclusion of the DNA intercalating fluorescent probe propidium iodide by viable cells. Pretreatment of cells with ADT (10 or 25 microM) for 18 hr significantly protected cells against H202- or HNE-induced cytotoxicity. Treatment of cells with ADT (10-50 microM) for 72 hr significantly increased the activities of catalase and glutathione reductase. The maximum effect of ADT treatment on the activity of these enzymes was observed when cells were treated with 25 microM of ADT for 72 hr. A significant increase in cellular GSH was observed in cells that were treated with ADT for 72 hr. Using monobromobimane as a thiol probe, we consistently observed that cells pretreated for 18 hr with ADT (25 or 50 microM) had also increased total thiol content. Exposure of Jurkat T cells to H202 or HNE resulted in a time-dependent decrease in cellular GSH. ADT (10-50 microM, 18 hr) pretreatment circumvented H202-dependent lowering of cellular GSH. In conclusion, ADT proved to be a potent cytoprotective thiol antioxidant with multifaceted mechanisms of action, suggesting that the drug has a remarkable therapeutic potential.

Gold Nanoparticles-Enhanced Proton Exchange Membrane (PEM) Fuel Cell

NASA Astrophysics Data System (ADS)

Li, Hongfei; Pan, Cheng; Liu, Ping; Zhu, Yimei; Adzic, Radoslav; Rafailovich, Miriam

Proton exchange membrane fuel cells have drawn great attention and been taken as a promising alternated energy source. One of the reasons hamper the wider application of PEM fuel cell is the catalytic poison effect from the impurity of the gas flow. Haruta has predicted that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate to be the perfect catalysts of the CO oxidization, yet the synthesis method is difficult to apply in the Fuel Cell. In our approach, thiol-functionalized gold nanoparticles were synthesized through two-phase method developed by Brust et al. We deposit these Au particles with stepped surface directly onto the Nafion membrane in the PEM fuel cell by Langmuir-Blodgett method, resulting in over 50% enhancement of the efficiency of the fuel cell. DFT calculations were conducted to understand the theory of this kind of enhancement. The results indicated that only when the particles were in direct surface contact with the membrane, where AuNPs attached at the end of the Nafion side chains, it could reduce the energy barrier for the CO oxidation that could happen at T<300K.

Redox Reactivity of Cerium Oxide Nanoparticles Induces the Formation of Disulfide Bridges in Thiol-Containing Biomolecules.

PubMed

Rollin-Genetet, Françoise; Seidel, Caroline; Artells, Ester; Auffan, Mélanie; Thiéry, Alain; Vidaud, Claude

2015-12-21

The redox state of disulfide bonds is implicated in many redox control systems, such as the cysteine-cystine couple. Among proteins, ubiquitous cysteine-rich metallothioneins possess thiolate metal binding groups susceptible to metal exchange in detoxification processes. CeO2 NPs are commonly used in various industrial applications due to their redox properties. These redox properties that enable dual oxidation states (Ce(IV)/Ce(III)) to exist at their surface may act as oxidants for biomolecules. The interaction among metallothioneins, cysteine, and CeO2 NPs was investigated through various biophysical approaches to shed light on the potential effects of the Ce(4+)/Ce(3+) redox system on the thiol groups of these biomolecules. The possible reaction mechanisms include the formation of a disulfide bridge/Ce(III) complex resulting from the interaction between Ce(IV) and the thiol groups, leading to metal unloading from the MTs, depending on their metal content and cluster type. The formation of stable Ce(3+) disulfide complexes has been demonstrated via their fluorescence properties. This work provides the first evidence of thiol concentration-dependent catalytic oxidation mechanisms between pristine CeO2 NPs and thiol-containing biomolecules.

Quaternary ammonium salts substituted by 5-phenyl-1,3,4-oxadiazole-2-thiol as novel antibacterial agents with low cytotoxicity.

PubMed

Wang, Chun-Hua; Xie, Xian-Rui; Liu, Wen-Shuai; Hou, Gui-Ge; Sun, Ju-Feng; Zhao, Feng; Cong, Wei; Li, Hong-Juan; Xin, Wen-Yu

2017-11-01

Twenty-one novel 5-phenyl-1,3,4-oxadiazole-2-thiol (POT) substituted N-hydroxyethyl quaternary ammonium salts (6a-g, 7a-g, 8a-g) were prepared and characterized by FTIR, NMR, and elemental analysis. Compounds 6a, 6c, and 8a were confirmed by X-ray single-crystal diffraction. They display the unsurpassed antibacterial activity against Staphylococcus aureus, α-H-tococcus, Escherichia coli, P. aeruginosa, Proteus vulgaris, Canidia Albicans, especially 6g, 7g, 8g with dodecyl group. Compounds 8a-d with N,N-dihydroxyethyl and POT groups display unsurpassed antibacterial activity and non-toxicity. The structure-activity relationships indicate that POT and flexible dihydroxyethyl group in QAS are necessary for antibacterial activity and cytotoxicity. SEM and TEM images of E. coli morphologies of 8d show the antibacterial agents can adhere to membrane surfaces to inhibit bacterial growth by disrupting peptidoglycan formation and releasing bacterial cytoplasm from cell membranes. © 2017 John Wiley & Sons A/S.

X-ray photoelectron spectroscopy characterization of gold nanoparticles functionalized with amine-terminated alkanethiols

PubMed Central

Techane, Sirnegeda D.; Gamble, Lara J.; Castner, David G.

2011-01-01

Gold nanoparticles (AuNPs) functionalized with a short chain amine-terminated alkanethiol (HS-(CH2)2NH2 or C2 NH2-thiol) are prepared via a direct synthesis method and then ligand-exchanged with a long chain amine-terminated alkanethiol (HS-(CH2)11NH2 or C11 NH2-thiol). Transmission electron microscopy analysis showed the AuNPs were relatively spherical with a median diameter of 24.2±4.3 nm. X-ray photoelectron spectroscopy was used to determine surface chemistry of the functionalized and purified AuNPs. The ligand-exchange process was monitored within the time range from 30 min to 61 days. By the fourth day of exchange all the C2 NH2-thiol molecules had been replaced by C11 NH2-thiol molecules. C11 NH2-thiol molecules continued to be incorporated into the C11 NH2 self-assembled monolayer between days 4 and 14 of ligand-exchange. As the length of the exchange time increased, the functionalized AuNPs became more stable against aggregation. The samples were purified by a centrifugation and resuspension method. The C2 NH2 covered AuNPs aggregated immediately when purification was attempted. The C11 NH2 covered AuNPs could be purified with minimal or no aggregation. Small amounts of unbound thiol (∼15%) and oxidized sulfur (∼20%) species were detected on the ligand-exchanged AuNPs. Some of the unbound thiol and all of the oxidized sulfur could be removed by treating the functionalized AuNPs with HCl. PMID:21974680

Hypoxia limits antioxidant capacity in red blood cells by altering glycolytic pathway dominance

PubMed Central

Rogers, Stephen C.; Said, Ahmed; Corcuera, Daniella; McLaughlin, Dylan; Kell, Pamela; Doctor, Allan

2009-01-01

The erythrocyte membrane is a newly appreciated platform for thiol-based circulatory signaling, and it requires robust free thiol maintenance. We sought to define physiological constraints on erythrocyte antioxidant defense. Hemoglobin (Hb) conformation gates glycolytic flux through the hexose monophosphate pathway (HMP), the sole source of nicotinamide adenine dinucleotide phosphate (NADPH) in erythrocytes. We hypothesized elevated intraerythrocytic deoxyHb would limit resilience to oxidative stress. Human erythrocytes were subjected to controlled oxidant (superoxide) loading following independent manipulation of oxygen tension, Hb conformation, and glycolytic pathway dominance. Sufficiency of antioxidant defense was determined by serial quantification of GSH, NADPH, NADH redox couples. Hypoxic erythrocytes demonstrated greater loss of reduction potential [Δ GSH Ehc (mV): 123.4±9.7 vs. 57.2±11.1] and reduced membrane thiol (47.7±5.7 vs. 20.1±4.3%) (hypoxia vs. normoxia, respectively; P<0.01), a finding mimicked in normoxic erythrocytes after HMP blockade. Rebalancing HMP flux during hypoxia restored resilience to oxidative stress at all stages of the system. Cell-free studies assured oxidative loading was not altered by oxygen tension, heme ligation, or the inhibitors employed. These data indicate that Hb conformation controls coupled glucose and thiol metabolism in erythrocytes, and implicate hypoxemia in the pathobiology of erythrocyte-based vascular signaling.—Rogers, S. C., Said, A., Corcuera, D., McLaughlin, D., Kell, P., Doctor, A. Hypoxia limits antioxidant capacity in red blood cells by altering glycolytic pathway dominance. PMID:19417084

Transdermal thiol-acrylate polyethylene glycol hydrogel synthesis using near infrared light

NASA Astrophysics Data System (ADS)

Chung, Solchan; Lee, Hwangjae; Kim, Hyung-Seok; Kim, Min-Gon; Lee, Luke P.; Lee, Jae Young

2016-07-01

Light-induced polymerization has been widely applied for hydrogel synthesis, which conventionally involves the use of ultraviolet or visible light to activate a photoinitiator for polymerization. However, with these light sources, transdermal gelation is not efficient and feasible due to their substantial interactions with biological systems, and thus a high power is required. In this study, we used biocompatible and tissue-penetrating near infrared (NIR) light to remotely trigger a thiol-acrylate reaction for efficient in vivo gelation with good controllability. Our gelation system includes gold nanorods as a photothermal agent, a thermal initiator, diacrylate polyethylene glycol (PEG), and thiolated PEG. Irradiation with a low-power NIR laser (0.3 W cm-2) could induce gelation via a mixed-mode reaction with a small increase in temperature (~5 °C) under the optimized conditions. We also achieved successful transdermal gelation via the NIR-assisted photothermal thiol-acryl reactions. This new type of NIR-assisted thiol-acrylate polymerization provides new opportunities for in situ hydrogel formation for injectable hydrogels and delivery of drugs/cells for various biomedical applications.Light-induced polymerization has been widely applied for hydrogel synthesis, which conventionally involves the use of ultraviolet or visible light to activate a photoinitiator for polymerization. However, with these light sources, transdermal gelation is not efficient and feasible due to their substantial interactions with biological systems, and thus a high power is required. In this study, we used biocompatible and tissue-penetrating near infrared (NIR) light to remotely trigger a thiol-acrylate reaction for efficient in vivo gelation with good controllability. Our gelation system includes gold nanorods as a photothermal agent, a thermal initiator, diacrylate polyethylene glycol (PEG), and thiolated PEG. Irradiation with a low-power NIR laser (0.3 W cm-2) could induce gelation via a mixed-mode reaction with a small increase in temperature (~5 °C) under the optimized conditions. We also achieved successful transdermal gelation via the NIR-assisted photothermal thiol-acryl reactions. This new type of NIR-assisted thiol-acrylate polymerization provides new opportunities for in situ hydrogel formation for injectable hydrogels and delivery of drugs/cells for various biomedical applications. Electronic supplementary information (ESI) available: FE-SEM image of thiol-acrylate hydrogels; UV/Vis spectra of Ellman's assay; the temperature increase during transdermal photothermal hydrogelation. See DOI: 10.1039/c6nr01956k

Photoluminescence and time-resolved carrier dynamics in thiol-capped CdTe nanocrystals under high pressure

NASA Astrophysics Data System (ADS)

Lin, Yan-Cheng; Chou, Wu-Ching; Susha, Andrei S.; Kershaw, Stephen V.; Rogach, Andrey L.

2013-03-01

The application of static high pressure provides a method for precisely controlling and investigating many fundamental and unique properties of semiconductor nanocrystals (NCs). This study systematically investigates the high-pressure photoluminescence (PL) and time-resolved carrier dynamics of thiol-capped CdTe NCs of different sizes, at different concentrations, and in various stress environments. The zincblende-to-rocksalt phase transition in thiol-capped CdTe NCs is observed at a pressure far in excess of the bulk phase transition pressure. Additionally, the process of transformation depends strongly on NC size, and the phase transition pressure increases with NC size. These peculiar phenomena are attributed to the distinctive bonding of thiols to the NC surface. In a nonhydrostatic environment, considerable flattening of the PL energy of CdTe NC powder is observed above 3.0 GPa. Furthermore, asymmetric and double-peak PL emissions are obtained from a concentrated solution of CdTe NCs under hydrostatic pressure, implying the feasibility of pressure-induced interparticle coupling.

Surface analysis of gold nanoparticles functionalized with thiol-modified glucose SAMs for biosensor applications.

NASA Astrophysics Data System (ADS)

Spampinato, Valentina; Parracino, Mariaantonietta; La Spina, Rita; Rossi, Francois; Ceccone, Giacomo

2016-02-01

In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Principal Component Analysis (PCA) and X-ray Photoelectron Spectroscopy (XPS) have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP). The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules. Both techniques were proved to be very useful tools for monitoring all the functionalization steps, including the investigation of the biological behaviour of the glucose-modified particles in presence of the maltose binding protein.

Leveraging zinc interstitials and oxygen vacancies for sensitive biomolecule detection through selective surface functionalization

NASA Astrophysics Data System (ADS)

Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Chaudhry, Shajee; Prasad, Shalini

2015-03-01

In this study, functionally engineered EIS technique was implemented to investigate the influence of surface functionalization on sensitivity of biomolecule detection using nanostructured ZnO platform. Organic molecules with thiol and carboxylic functional groups were chosen to control biomolecule immobilization on zinc and oxygen-terminated 2D planar and 1D nanostructured ZnO surfaces. The amount of functionalization and its influence on charge perturbations at the ZnO-electrolyte interface were studied using fluorescence and EIS measurements. We observed the dependence of charge transfer on both the polarity of platform and concentration of cross-linker molecules. Such selectively modified surfaces were used for detection of cortisol, a major stress indicator. Results demonstrated preferential binding of thiol groups to Zn terminations and thus leveraging ZnO interstitials increases the sensitivity of detection over larger dynamic range with detection limit at 10fg/mL.

Surface Analysis of Gold Nanoparticles Functionalized with Thiol-Modified Glucose SAMs for Biosensor Applications

PubMed Central

Spampinato, Valentina; Parracino, Maria Antonietta; La Spina, Rita; Rossi, Francois; Ceccone, Giacomo

2016-01-01

In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Principal Component Analysis (PCA) and X-ray Photoelectron Spectroscopy (XPS) have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP). The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules. Both techniques were proved to be very useful tools for monitoring all the functionalization steps, including the investigation of the biological behavior of the glucose-modified particles in the presence of the maltose binding protein. PMID:26973830

Preparation of thiol-functionalized activated carbon from sewage sludge with coal blending for heavy metal removal from contaminated water.

PubMed

Li, Juan; Xing, Xing; Li, Jiao; Shi, Mei; Lin, Aijun; Xu, Congbin; Zheng, Jianzhong; Li, Ronghua

2018-03-01

Sewage sludge produced from wastewater treatment is a pressing environmental issue. Mismanagement of the massive amount of sewage sludge would threat our valuble surface and shallow ground water resources. Use of activated carbon prepared from carbonization of these sludges for heavy metal removal can not only minimize and stabilize these hazardous materials but also realize resources reuse. In this study, thiol-functionalized activated carbon was synthesized from coal-blended sewage sludge, and its capacity was examined for removing Cu(II), Pb(II), Cd(II) and Ni(II) from water. Pyrolysis conditions to prepare activated carbons from the sludge and coal mixture were examined, and the synthesized material was found to achieve the highest BET surface area of 1094 m 2 /g under 500 °C and 30 min. Batch equilibrium tests indicated that the thiol-functionalized activated carbon had a maximum sorption capacity of 238.1, 96.2, 87.7 and 52.4 mg/g for Pb(II), Cd(II), Cu(II) and Ni(II) removal from water, respectively. Findings of this study suggest that thiol-functionalized activated carbon prepared from coal-blended sewage sludge would be a promising sorbent material for heavy metal removal from waters contaminated with Cu(II), Pb(II), Cd(II) and Ni(II). Copyright © 2017 Elsevier Ltd. All rights reserved.

Integrating a high-force optical trap with gold nanoposts and a robust gold-DNA bond.

PubMed

Paik, D Hern; Seol, Yeonee; Halsey, Wayne A; Perkins, Thomas T

2009-08-01

Gold-thiol chemistry is widely used in nanotechnology but has not been exploited in optical-trapping experiments due to laser-induced ablation of gold. We circumvented this problem by using an array of gold nanoposts (r = 50-250 nm, h approximately 20 nm) that allowed for quantitative optical-trapping assays without direct irradiation of the gold. DNA was covalently attached to the gold via dithiol phosphoramidite (DTPA). By using three DTPAs, the gold-DNA bond was not cleaved in the presence of excess thiolated compounds. This chemical robustness allowed us to reduce nonspecific sticking by passivating the unreacted gold with methoxy-(polyethylene glycol)-thiol. We routinely achieved single beads anchored to the nanoposts by single DNA molecules. We measured DNA's elasticity and its overstretching transition, demonstrating moderate- and high-force optical-trapping assays using gold-thiol chemistry. Force spectroscopy measurements were consistent with the rupture of the strepavidin-biotin bond between the bead and the DNA. This implied that the DNA remained anchored to the surface due to the strong gold-thiol bond. Consistent with this conclusion, we repeatedly reattached the trapped bead to the same individual DNA molecule. Thus, surface conjugation of biomolecules onto an array of gold nanostructures by chemically and mechanically robust bonds provides a unique way to carry out spatially controlled, repeatable measurements of single molecules.

Formation of 4-ethoxy-4'-nitrosodiphenylamine in the reaction of the phenacetin metabolite 4-nitrosophenetol with glutathione.

PubMed

Klehr, H; Eyer, P; Schäfer, W

1987-08-01

Phenacetin, a constituent of several analgesic and antipyretic formulations has been made responsible for a variety of toxic and carcinogenic actions. 4-Nitrosophenetol, the N-oxydation product of intermediate 4-phenetidine, forms methemoglobin and binds covalently to sulfhydryl groups of proteins and glutathione. In the reaction of 4-nitrosophenetol with glutathione and other thiols an intermediate so-called "semimercaptal" is formed from which N-(thiol-S-yl)-4-phenetidine S-oxide, N-(thiol-S-yl)-4-phenetidine and 4-phenetidine derive. Besides thiol adducts, a yellow compound is formed which was isolated as a pure crystalline product (elemental analysis) and identified by FAB-MS, EI-MS, 13C-, 1H-NMR, and UV-VIS spectroscopy as 4-ethoxy-4'-nitrosodiphenylamine. This nitrosoarene is formed by an unknown mechanism from 4-nitrosophenetol and 4-phenetidine under liberation of ethanol. In human erythrocytes this compound is easily reduced to 4-amino-4'-ethoxydiphenylamine (FAB-MS, EI-MS, 13C-NMR). During the reaction of 4-nitrosophenetol with red cells only traces of 4-ethoxy-4'-nitrosodiphenylamine were formed, whereas up to 10% appeared as the reduction product 4-amino-4'-ethoxydiphenylamine. This latter compound is unstable in red cells and is metabolized further to unidentified products.

Thiolated graphene - a new platform for anchoring CdSe quantum dots for hybrid heterostructures

NASA Astrophysics Data System (ADS)

Debgupta, Joyashish; Pillai, Vijayamohanan K.

2013-04-01

Effective organization of small CdSe quantum dots on graphene sheets has been achieved by a simple solution exchange with thiol terminated graphene prepared by diazonium salt chemistry. This generic methodology of CdSe QD attachment to any graphene surface has remarkable implications in designing hybrid heterostructures.Effective organization of small CdSe quantum dots on graphene sheets has been achieved by a simple solution exchange with thiol terminated graphene prepared by diazonium salt chemistry. This generic methodology of CdSe QD attachment to any graphene surface has remarkable implications in designing hybrid heterostructures. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00363a

Protein Thiol Redox Signaling in Monocytes and Macrophages.

PubMed

Short, John D; Downs, Kevin; Tavakoli, Sina; Asmis, Reto

2016-11-20

Monocyte and macrophage dysfunction plays a critical role in a wide range of inflammatory disease processes, including obesity, impaired wound healing diabetic complications, and atherosclerosis. Emerging evidence suggests that the earliest events in monocyte or macrophage dysregulation include elevated reactive oxygen species production, thiol modifications, and disruption of redox-sensitive signaling pathways. This review focuses on the current state of research in thiol redox signaling in monocytes and macrophages, including (i) the molecular mechanisms by which reversible protein-S-glutathionylation occurs, (ii) the identification of bona fide S-glutathionylated proteins that occur under physiological conditions, and (iii) how disruptions of thiol redox signaling affect monocyte and macrophage functions and contribute to atherosclerosis. Recent Advances: Recent advances in redox biochemistry and biology as well as redox proteomic techniques have led to the identification of many new thiol redox-regulated proteins and pathways. In addition, major advances have been made in expanding the list of S-glutathionylated proteins and assessing the role that protein-S-glutathionylation and S-glutathionylation-regulating enzymes play in monocyte and macrophage functions, including monocyte transmigration, macrophage polarization, foam cell formation, and macrophage cell death. Protein-S-glutathionylation/deglutathionylation in monocytes and macrophages has emerged as a new and important signaling paradigm, which provides a molecular basis for the well-established relationship between metabolic disorders, oxidative stress, and cardiovascular diseases. The identification of specific S-glutathionylated proteins as well as the mechanisms that control this post-translational protein modification in monocytes and macrophages will facilitate the development of new preventive and therapeutic strategies to combat atherosclerosis and other metabolic diseases. Antioxid. Redox Signal. 25, 816-835.

A smart multifunctional drug delivery nanoplatform for targeting cancer cells

NASA Astrophysics Data System (ADS)

Hoop, M.; Mushtaq, F.; Hurter, C.; Chen, X.-Z.; Nelson, B. J.; Pané, S.

2016-06-01

Wirelessly guided magnetic nanomachines are promising vectors for targeted drug delivery, which have the potential to minimize the interaction between anticancer agents and healthy tissues. In this work, we propose a smart multifunctional drug delivery nanomachine for targeted drug delivery that incorporates a stimuli-responsive building block. The nanomachine consists of a magnetic nickel (Ni) nanotube that contains a pH-responsive chitosan hydrogel in its inner cavity. The chitosan inside the nanotube serves as a matrix that can selectively release drugs in acidic environments, such as the extracellular space of most tumors. Approximately a 2.5 times higher drug release from Ni nanotubes at pH = 6 is achieved compared to that at pH = 7.4. The outside of the Ni tube is coated with gold. A fluorescein isothiocyanate (FITC) labeled thiol-ssDNA, a biological marker, was conjugated on its surface by thiol-gold click chemistry, which enables traceability. The Ni nanotube allows the propulsion of the device by means of external magnetic fields. As the proposed nanoarchitecture integrates different functional building blocks, our drug delivery nanoplatform can be employed for carrying molecular drug conjugates and for performing targeted combinatorial therapies, which can provide an alternative and supplementary solution to current drug delivery technologies.Wirelessly guided magnetic nanomachines are promising vectors for targeted drug delivery, which have the potential to minimize the interaction between anticancer agents and healthy tissues. In this work, we propose a smart multifunctional drug delivery nanomachine for targeted drug delivery that incorporates a stimuli-responsive building block. The nanomachine consists of a magnetic nickel (Ni) nanotube that contains a pH-responsive chitosan hydrogel in its inner cavity. The chitosan inside the nanotube serves as a matrix that can selectively release drugs in acidic environments, such as the extracellular space of most tumors. Approximately a 2.5 times higher drug release from Ni nanotubes at pH = 6 is achieved compared to that at pH = 7.4. The outside of the Ni tube is coated with gold. A fluorescein isothiocyanate (FITC) labeled thiol-ssDNA, a biological marker, was conjugated on its surface by thiol-gold click chemistry, which enables traceability. The Ni nanotube allows the propulsion of the device by means of external magnetic fields. As the proposed nanoarchitecture integrates different functional building blocks, our drug delivery nanoplatform can be employed for carrying molecular drug conjugates and for performing targeted combinatorial therapies, which can provide an alternative and supplementary solution to current drug delivery technologies. Electronic supplementary information (ESI) available: Fig. S1 drug release control experiment; Fig. S2 cell viability assay; video - magnetic manipulation. See DOI: 10.1039/c6nr02228f

Involvement of thiol-based mechanisms in plant development.

PubMed

Rouhier, Nicolas; Cerveau, Delphine; Couturier, Jérémy; Reichheld, Jean-Philippe; Rey, Pascal

2015-08-01

Increasing knowledge has been recently gained regarding the redox regulation of plant developmental stages. The current state of knowledge concerning the involvement of glutathione, glutaredoxins and thioredoxins in plant development is reviewed. The control of the thiol redox status is mainly ensured by glutathione (GSH), a cysteine-containing tripeptide and by reductases sharing redox-active cysteines, glutaredoxins (GRXs) and thioredoxins (TRXs). Indeed, thiol groups present in many regulatory proteins and metabolic enzymes are prone to oxidation, ultimately leading to post-translational modifications such as disulfide bond formation or glutathionylation. This review focuses on the involvement of GSH, GRXs and TRXs in plant development. Recent studies showed that the proper functioning of root and shoot apical meristems depends on glutathione content and redox status, which regulate, among others, cell cycle and hormone-related processes. A critical role of GRXs in the formation of floral organs has been uncovered, likely through the redox regulation of TGA transcription factor activity. TRXs fulfill many functions in plant development via the regulation of embryo formation, the control of cell-to-cell communication, the mobilization of seed reserves, the biogenesis of chloroplastic structures, the metabolism of carbon and the maintenance of cell redox homeostasis. This review also highlights the tight relationships between thiols, hormones and carbon metabolism, allowing a proper development of plants in relation with the varying environment and the energy availability. GSH, GRXs and TRXs play key roles during the whole plant developmental cycle via their antioxidant functions and the redox-regulation of signaling pathways. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation. Copyright © 2015 Elsevier B.V. All rights reserved.

Phospholipase A2 activation regulates cytotoxicity of methylmercury in vascular endothelial cells.

PubMed

Mazerik, Jessica N; Hagele, Thomas; Sherwani, Shariq; Ciapala, Valorie; Butler, Susan; Kuppusamy, M Lakshmi; Hunter, Melissa; Kuppusamy, Periannan; Marsh, Clay B; Parinandi, Narasimham L

2007-01-01

Mercury has been identified as a risk factor for cardiovascular disease among humans. Through diet, mainly fish consumption, humans are exposed to methylmercury, the biomethylated organic form of environmental mercury. As the endothelium is an important player in homeostasis of the cardiovascular system, here, the authors tested their hypothesis that methylmercury activates the lipid signaling enzyme phospholipase A(2) (PLA(2)) in vascular endothelial cells (ECs), causing upstream regulation of cytotoxicity. To test this hypothesis, the authors used bovine pulmonary artery ECs (BPAECs) cultured in monolayers, following labeling of their membrane phospholipids with [(3)H]arachidonic acid (AA). The cells were exposed to methylmercury chloride (MMC) and then the release of free AA (index of PLA(2) activity) and lactate dehydrogenase (LDH; index of cytotoxicity) were determined by liquid scintillation counting and spectrophotometry, respectively. MMC significantly activated PLA(2) in a dose-dependent (5 to 15 microM) and time-dependent (0 to 60 min) fashion. Sulfhydryl (thiol-protective) agents, calcium chelators, antioxidants, and PLA(2)-specific inhibitors attenuated the MMC-induced PLA(2) activation, suggesting the role of thiols, reactive oxygen species (ROS), and calcium in the activation of PLA(2) in BPAECs. MMC also induced the loss of thiols and increase of lipid peroxidation in BPAECs. MMC induced cytotoxicity in BPAECs as observed by the altered cell morphology and LDH leak, which was significantly attenuated by PLA(2) inhibitors. This study established that PLA(2) activation through thiols, calcium, and oxidative stress was associated with the cytotoxicity of MMC in BPAECs, drawing attention to the involvement of PLA(2) signaling in the methylmercury-induced vascular endothelial dysfunctions.

A Simultaneously Antimicrobial, Protein-Repellent, and Cell-Compatible Polyzwitterion Network.

PubMed

Kurowska, Monika; Eickenscheidt, Alice; Guevara-Solarte, Diana-Lorena; Widyaya, Vania Tanda; Marx, Franziska; Al-Ahmad, Ali; Lienkamp, Karen

2017-04-10

A simultaneously antimicrobial, protein-repellent, and cell-compatible surface-attached polymer network is reported, which reduces the growth of bacterial biofilms on surfaces through its multifunctionality. The coating was made from a poly(oxonorbornene)-based zwitterion (PZI), which was surface-attached and cross-linked in one step by simultaneous UV-activated CH insertion and thiol-ene reaction. The process was applicable to both laboratory surfaces like silicon, glass, and gold and real-life surfaces like polyurethane foam wound dressings. The chemical structure and physical properties of the PZI surface and the two reference surfaces SMAMP ("synthetic mimic of an antimicrobial peptide"), an antimicrobial but protein-adhesive polymer coating, and PSB (poly(sulfobetaine)), a protein-repellent but not antimicrobial polyzwitterion coating were characterized by Fourier transform infrared spectroscopy, ellipsometry, contact angle measurements, photoelectron spectroscopy, swellability measurements (using surface plasmon resonance spectroscopy, SPR), zeta potential measurements, and atomic force microscopy. The time-dependent antimicrobial activity assay (time-kill assay) confirmed the high antimicrobial activity of the PZI; SPR was used to demonstrate that it was also highly protein-repellent. Biofilm formation studies showed that the material effectively reduced the growth of Escherichia coli and Staphylococcus aureus biofilms. Additionally, it was shown that the PZI was highly compatible with immortalized human mucosal gingiva keratinocytes and human red blood cells using the Alamar Blue assay, the live-dead stain, and the hemolysis assay. PZI thus may be an attractive coating for biomedical applications, particularly for the fight against bacterial biofilms on medical devices and in other applications.

Eucalyptus tolerance mechanisms to lanthanum and cerium: subcellular distribution, antioxidant system and thiol pools.

PubMed

Shen, Yichang; Zhang, Shirong; Li, Sen; Xu, Xiaoxun; Jia, Yongxia; Gong, Guoshu

2014-12-01

Guanglin 9 (Eucalyptus grandis × Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200 mg kg(-1), while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200 mg kg(-1), and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Photonic activation of disulfide bridges achieves oriented protein immobilization on biosensor surfaces.

PubMed

Neves-Petersen, Maria Teresa; Snabe, Torben; Klitgaard, Søren; Duroux, Meg; Petersen, Steffen B

2006-02-01

Photonic induced immobilization is a novel technology that results in spatially oriented and spatially localized covalent coupling of biomolecules onto thiol-reactive surfaces. Immobilization using this technology has been achieved for a wide selection of proteins, such as hydrolytic enzymes (lipases/esterases, lysozyme), proteases (human plasminogen), alkaline phosphatase, immunoglobulins' Fab fragment (e.g., antibody against PSA [prostate specific antigen]), Major Histocompability Complex class I protein, pepsin, and trypsin. The reaction mechanism behind the reported new technology involves "photonic activation of disulfide bridges," i.e., light-induced breakage of disulfide bridges in proteins upon UV illumination of nearby aromatic amino acids, resulting in the formation of free, reactive thiol groups that will form covalent bonds with thiol-reactive surfaces (see Fig. 1). Interestingly, the spatial proximity of aromatic residues and disulfide bridges in proteins has been preserved throughout molecular evolution. The new photonic-induced method for immobilization of proteins preserves the native structural and functional properties of the immobilized protein, avoiding the use of one or more chemical/thermal steps. This technology allows for the creation of spatially oriented as well as spatially defined multiprotein/DNA high-density sensor arrays with spot size of 1 microm or less, and has clear potential for biomedical, bioelectronic, nanotechnology, and therapeutic applications.

Recent advances in self-assembled monolayers based biomolecular electronic devices.

PubMed

Arya, Sunil K; Solanki, Pratima R; Datta, Monika; Malhotra, Bansi D

2009-05-15

Self-assembled monolayers (SAMs) have aroused much interest due to their potential applications in biosensors, biomolecular electronics and nanotechnology. This has been largely attributed to their inherent ordered arrangement and controllable properties. SAMs can be formed by chemisorption of organic molecules containing groups like thiols, disulphides, amines, acids or silanes, on desired surfaces and can be used to fabricate biomolecular electronic devices. We focus on recent applications of organosulphur compounds (thiols) based SAMs to biomolecular electronic devices in the last about 3 years.

Colloidal Stability of Gold Nanoparticles Coated with Multithiol-Poly(ethylene glycol) Ligands: Importance of Structural Constraints of the Sulfur Anchoring Groups

DTIC Science & Technology

2013-08-13

21-45 Citric acid has been the most commonly used ligand when negatively charged surfaces or a rather loose ligand shell is required for further...biomolecules in biological serum (e.g., proteins, peptides, nucleic acids ); (5) resistance to heat treatments (e.g., >80 °C for DNA hybridization).6-8, 16...demonstrated by a variety of thiol-based ligands such as mercaptopropionic acid ,36 glutathione,37 thiol-terminated poly(ethylene glycol) (PEG-SH), 19

Redox regulation of mitochondrial proteins and proteomes by cysteine thiol switches.

PubMed

Nietzel, Thomas; Mostertz, Jörg; Hochgräfe, Falko; Schwarzländer, Markus

2017-03-01

Mitochondria are hotspots of cellular redox biochemistry. Respiration as a defining mitochondrial function is made up of a series of electron transfers that are ultimately coupled to maintaining the proton motive force, ATP production and cellular energy supply. The individual reaction steps involved require tight control and flexible regulation to maintain energy and redox balance in the cell under fluctuating demands. Redox regulation by thiol switching has been a long-standing candidate mechanism to support rapid adjustment of mitochondrial protein function at the posttranslational level. Here we review recent advances in our understanding of cysteine thiol switches in the mitochondrial proteome with a focus on their operation in vivo. We assess the conceptual basis for thiol switching in mitochondria and discuss to what extent insights gained from in vitro studies may be valid in vivo, considering thermodynamic, kinetic and structural constraints. We compare functional proteomic approaches that have been used to assess mitochondrial protein thiol switches, including thioredoxin trapping, redox difference gel electrophoresis (redoxDIGE), isotope-coded affinity tag (OxICAT) and iodoacetyl tandem mass tag (iodoTMT) labelling strategies. We discuss conditions that may favour active thiol switching in mitochondrial proteomes in vivo, and appraise recent advances in dissecting their impact using combinations of in vivo redox sensing and quantitative redox proteomics. Finally we focus on four central facets of mitochondrial biology, aging, carbon metabolism, energy coupling and electron transport, exemplifying the current emergence of a mechanistic understanding of mitochondrial regulation by thiol switching in living plants and animals. Copyright © 2016 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

Formulation of glutathione responsive anti-proliferative nanoparticles from thiolated Akt1 siRNA and disulfide-crosslinked PEI for efficient anti-cancer gene therapy.

PubMed

Muthiah, Muthunarayanan; Che, Hui-Lian; Kalash, Santhosh; Jo, Jihoon; Choi, Seok-Yong; Kim, Won Jong; Cho, Chong Su; Lee, Jae Young; Park, In-Kyu

2015-02-01

In this study, thiol-modified siRNA (SH-siRNA) was delivered by bioreducible polyethylenimine (ssPEI), to enhance physicochemical properties of polyplexes and function of siRNA through disulfide bonding between SH-siRNA and ssPEI. The ssPEI was utilized to deliver Akt1 SH-siRNA for suppression of Akt1 mRNA and blockage of Akt1 protein translation, resulting in reduced cellular proliferation and the induction of apoptosis. Disulfide bondings between the ssPEI and SH-siRNA through thiol groups in both were confirmed by DTT treatment. Complexation between ssPEI and Akt1SH-siRNA was enhanced and reduced surface charge of ssPEI/Akt1SH-siRNA complexes with smaller average particle sizes even at lower N/P ratios was obtained compared with PEI/Akt1siRNA ones. Cellular uptake of ssPEI/Akt1SH-siRNA complexes in CT-26 mouse colon cancer cells was also enhanced. The ssPEI/Akt1SH-siRNA complexes reduced proliferation and increased apoptosis of mouse colon cancer cells in vitro. In an in vivo mouse tumor model, the complexes reduced tumor proliferation and downregulation of Akt1 compared to controls. Copyright © 2014 Elsevier B.V. All rights reserved.

Sera from cancer patients contain two oscillating ECTO-NOX activities with different period lengths

NASA Technical Reports Server (NTRS)

Wang, Sui; Morre, Dorothy M.; Morre, D. James

2003-01-01

ECTO-NOX protein's are cell surface-associated and growth-related hydroquinone oxidases with both protein disulfide-thiol interchange activity and the capacity to oxidize NAD(P)H. The activities of these ECTO-NOX proteins are not steady state but fluctuate to create a repeating pattern of oscillations. Two forms of ECTO-NOX activities have been distinguished. The constitutive ECTO-NOX (CNOX), is hormone responsive and refractory to quinone-site inhibitors. A tumor-associated NOX (tNOX) is unregulated, refractory to hormones and growth factors and responds to quinone-site inhibitors. CNOX proteins are widely distributed and exhibit oscillations in enzymatic activity with a period length of 24 min. tNOX proteins are cancer specific and exhibit oscillations with a period length of about 22 min. Our findings now demonstrate the presence of the novel oscillating tNOX activity in sera of patients with cancer whereas the constitutive NOX of non-cancer cells is present in sera of both cancer patients and healthy volunteers. We conclude that ECTO-NOX proteins in sera exhibit oscillatory characteristics similar to those of ECTO-NOX forms of the cell surface.

PEG-coated gold nanorod monoclonal antibody conjugates in preclinical research with optoacoustic tomography, photothermal therapy, and sensing

NASA Astrophysics Data System (ADS)

Liopo, Anton V.; Conjusteau, André; Oraevsky, Alexander A.

2012-02-01

Gold nanorods (GNR) with a peak absorption wavelength of 760 nm were prepared using a seed-mediated method. A novel protocol has been developed to replace hexadecyltrimethylammonium bromide (CTAB) on the surface of GNR with 16-mercaptohexadecanoic acid (MHDA) and metoxy-poly(ethylene glycol)-thiol (PEG), and the monoclonal antibodies: HER2 or CD33. The physical chemistry property of the conjugates was monitored through optical and zetapotential measurements to confirm surface chemistry. The plasmon resonance is kept in the near infrared area, and changes from strong positive charge for GNR-CTAB to slightly negative for GNR-PEG-mAb conjugates are observed. The conjugates were investigated for different cells lines: breast cancer cells and human leukemia lines in vivo applications. These results demonstrate successful tumor accumulation of our modified PEG-MHDA conjugates of GNR for HER2/neu in both overexpressed breast tumors in nude mice, and for thermolysis of human leukemia cells in vitro. The conjugates are non-toxic and can be used in pre-clinical applications, as well as molecular and optoacoustic imaging, and quantitative sensing of biological substrates.

Regulation of Cell Physiology and Pathology by Protein S-Glutathionylation: Lessons Learned from the Cardiovascular System

PubMed Central

Pimentel, David; Haeussler, Dagmar Johanna; Matsui, Reiko; Burgoyne, Joseph Robert; Cohen, Richard Alan

2012-01-01

Abstract Significance: Reactive oxygen and nitrogen species contributing to homeostatic regulation and the pathogenesis of various cardiovascular diseases, including atherosclerosis, hypertension, endothelial dysfunction, and cardiac hypertrophy, is well established. The ability of oxidant species to mediate such effects is in part dependent on their ability to induce specific modifications on particular amino acids, which alter protein function leading to changes in cell signaling and function. The thiol containing amino acids, methionine and cysteine, are the only oxidized amino acids that undergo reduction by cellular enzymes and are, therefore, prime candidates in regulating physiological signaling. Various reports illustrate the significance of reversible oxidative modifications on cysteine thiols and their importance in modulating cardiovascular function and physiology. Recent Advances: The use of mass spectrometry, novel labeling techniques, and live cell imaging illustrate the emerging importance of reversible thiol modifications in cellular redox signaling and have advanced our analytical abilities. Critical Issues: Distinguishing redox signaling from oxidative stress remains unclear. S-nitrosylation as a precursor of S-glutathionylation is controversial and needs further clarification. Subcellular distribution of glutathione (GSH) may play an important role in local regulation, and targeted tools need to be developed. Furthermore, cellular redundancies of thiol metabolism complicate analysis and interpretation. Future Directions: The development of novel pharmacological analogs that specifically target subcellular compartments of GSH to promote or prevent local protein S-glutathionylation as well as the establishment of conditional gene ablation and transgenic animal models are needed. Antioxid. Redox Signal. 16, 524–542. PMID:22010840

AFM Study of Surface Nanobubbles on Binary Self-Assembled Monolayers on Ultraflat Gold with Identical Macroscopic Static Water Contact Angles and Different Terminal Functional Groups.

PubMed

Song, Bo; Chen, Kun; Schmittel, Michael; Schönherr, Holger

2016-11-01

All experimental findings related to surface nanobubbles, such as their pronounced stability and the striking differences of macroscopic and apparent nanoscopic contact angles, need to be addressed in any theory or model of surface nanobubbles. In this work we critically test a recent explanation of surface nanobubble stability and their consequences and contrast this with previously proposed models. In particular, we elucidated the effect of surface chemical composition of well-controlled solid-aqueous interfaces of identical roughness and defect density on the apparent nanoscopic contact angles. Expanding on a previous atomic force microscopy (AFM) study on the systematic variation of the macroscopic wettability using binary self-assembled monolayers (SAMs) on ultraflat template stripped gold (TSG), we assessed here the effect of different surface chemical composition for macroscopically identical static water contact angles. SAMs on TSG with a constant macroscopic water contact angle of 81 ± 2° were obtained by coadsorption of a methyl-terminated thiol and a second thiol with different terminal functional groups, including hydroxy, amino, and carboxylic acid groups. In addition, surface nanobubbles formed by entrainment of air on SAMs of a bromoisobutyrate-terminated thiol were analyzed by AFM. Despite the widely differing surface potentials and different functionality, such as hydrogen bond acceptor or donor, and different dipole moments and polarizability, the nanoscopic contact angles (measured through the condensed phase and corrected for AFM tip broadening effects) were found to be 145 ± 10° for all surfaces. Hence, different chemical functionalities at identical macroscopic static water contact angle do not noticeably influence the apparent nanoscopic contact angle of surface nanobubbles. This universal contact angle is in agreement with recent models that rely on contact line pinning and the equilibrium of gas outflux due to the Laplace pressure and gas influx due to gas oversaturation in the aqueous medium.

Preactivated thiolated pullulan as a versatile excipient for mucosal drug targeting.

PubMed

Leonaviciute, Gintare; Suchaoin, Wongsakorn; Matuszczak, Barbara; Lam, Hung Thanh; Mahmood, Arshad; Bernkop-Schnürch, Andreas

2016-10-20

The purpose of the present study was to generate a novel mucoadhesive thiolated pullulan with protected thiol moieties and to evaluate its suitability as mucosal drug delivery system. Two different synthetic pathways: bromination-nucleophilic substitution and reductive amination including periodate cleavage were utilized to synthesize such thiolated pullulans. The thiomer (pullulan-cysteamine) with the highest amount of free thiol groups was further enrolled in a reaction with 6-mercaptonicotinamide and its presence in pullulan structure was confirmed via NMR analysis. Furthermore, unmodified, thiolated and preactivated thiolated pullulan were investigated in terms of mucoadhesion via rotating cylinder studies and rheological synergism method as well as their toxicity potential over Caco-2 cells. Comparing both methods the reductive amination seems to be the method of choice resulting in comparatively higher coupling rates. Using this procedure pullulan-cysteamine conjugate displayed 1522±158μmol immobilized thiol groups and 280±70μmol free thiol groups per gram polymer. Furthermore, 82% of free thiol groups on this conjugate were linked with 6-mercaptonicotinamide (6-MNA). The adhesion time on the rotating cylinder was up to 46-fold prolonged in case of the thiolated polymer and up to 75-fold in case of the preactivated polymer. Rheological measurements of modified pullulan samples showed 98-fold and 160-fold increase in dynamic viscosity upon the addition of mucus within 60min, whereas unmodified pullulan did not show an increase in viscosity at all. Both conjugates had a minor effect on Caco-2 cell viability. Because of these features preactivated thiolated pullulan seems to represent a promising type of mucoadhesive polymers for the development of various mucosal drug delivery systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of antibody disulfide bond reduction on purification process performance and final drug substance stability

PubMed Central

Russell, Brian; Yang, Yanhong; Handlogten, Michael; Hudak, Suzanne; Cao, Mingyan; Wang, Jihong; Robbins, David; Ahuja, Sanjeev; Zhu, Min

2017-01-01

ABSTRACT Antibody disulfide bond reduction during monoclonal antibody (mAb) production is a phenomenon that has been attributed to the reducing enzymes from CHO cells acting on the mAb during the harvest process. However, the impact of antibody reduction on the downstream purification process has not been studied. During the production of an IgG2 mAb, antibody reduction was observed in the harvested cell culture fluid (HCCF), resulting in high fragment levels. In addition, aggregate levels increased during the low pH treatment step in the purification process. A correlation between the level of free thiol in the HCCF (as a result of antibody reduction) and aggregation during the low pH step was established, wherein higher levels of free thiol in the starting sample resulted in increased levels of aggregates during low pH treatment. The elevated levels of free thiol were not reduced over the course of purification, resulting in carry‐over of high free thiol content into the formulated drug substance. When the drug substance with high free thiols was monitored for product degradation at room temperature and 2–8°C, faster rates of aggregation were observed compared to the drug substance generated from HCCF that was purified immediately after harvest. Further, when antibody reduction mitigations (e.g., chilling, aeration, and addition of cystine) were applied, HCCF could be held for an extended period of time while providing the same product quality/stability as material that had been purified immediately after harvest. Biotechnol. Bioeng. 2017;114: 1264–1274. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals Inc. PMID:28186329

Reversible Stabilization of Vesicles: Redox-Responsive Polymer Nanocontainers for Intracellular Delivery.

PubMed

de Vries, Wilke C; Grill, David; Tesch, Matthias; Ricker, Andrea; Nüsse, Harald; Klingauf, Jürgen; Studer, Armido; Gerke, Volker; Ravoo, Bart Jan

2017-08-01

We present the self-assembly of redox-responsive polymer nanocontainers comprising a cyclodextrin vesicle core and a thin reductively cleavable polymer shell anchored via host-guest recognition on the vesicle surface. The nanocontainers are of uniform size, show high stability, and selectively respond to a mild reductive trigger as revealed by dynamic light scattering, transmission electron microscopy, atomic force microscopy, a quantitative thiol assay, and fluorescence spectroscopy. Live cell imaging experiments demonstrate a specific redox-responsive release and cytoplasmic delivery of encapsulated hydrophilic payloads, such as the pH-probe pyranine, and the fungal toxin phalloidin. Our results show the high potential of these stimulus-responsive nanocontainers for cell biological applications requiring a controlled delivery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel fluorescent assay for edaravone with aqueous functional CdSe quantum dots

NASA Astrophysics Data System (ADS)

Liao, Ping; Yan, Zheng-Yu; Xu, Zhi-Ji; Sun, Xiao

2009-06-01

Aqueous thiol-capped CdSe QDs with a narrow, symmetric emission were prepared under a low temperature. Based on the fluorescence enhancement of thiol-stabilized CdSe quantum dots (QDs) caused by edaravone, a simple, rapid and specific quantitative method was proposed to the edaravone determination. The concentration dependence of fluorescence intensity followed the binding of edaravone to surface of the thiol-capped CdSe QDs was effectively described by a modified Langmuir-type binding isotherm. Factors affecting the fluorescence detection for edaravone with thiol-stabilized CdSe QDs were studied, such as the effect of pH, reaction time, the concentration of CdSe QDs and so on. Under the optimal conditions, the calibration plot of C/( I - I0) with concentration of edaravone was linear in the range of (1.45-17.42) μg/mL (0.008-0.1 μmol/L) with correlation coefficient of 0.998. The limit of detection (LOD) (3 σ/ κ) was 0.15 μg/mL (0.0009 μmol/mL). Possible interaction mechanism was discussed.

Spontaneous desorption and phase transitions of self-assembled alkanethiol and alicyclic thiol monolayers chemisorbed on Au(111) in ultrahigh vacuum at room temperature.

PubMed

Ito, Eisuke; Kang, Hungu; Lee, Dongjin; Park, Joon B; Hara, Masahiko; Noh, Jaegeun

2013-03-15

Scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) were used to examine the surface structure and adsorption conditions of hexanethiol (HT) and cyclohexanethiol (CHT) self-assembled monolayers (SAMs) on Au(111) as a function of storage period in ultrahigh vacuum (UHV) conditions of 3×10(-7) Pa at room temperature (RT). STM imaging revealed that after storage for 7 days, HT SAMs underwent phase transitions from c(4×2) phase to low coverage 4×√3 phase. This transition is due to a structural rearrangement of hexanethiolates that results from the spontaneous desorption of chemisorbed HT molecules on Au(111) surface. XPS measurements showed approximately 28% reduction in sulfur coverage, which indicates desorption of hexanethiolates from the surfaces. Contrary to HT SAMs, the structural order of CHT SAMs with (5×2√3)R35° phase completely disappeared after storage for 3 or 7 days. XPS results show desorption of more than 80% of the cyclohexanethiolates, even after storage for 3 days. We found that spontaneous desorption of CHT molecules on Au(111) in UHV at RT occurred quickly, whereas spontaneous desorption of HT molecules was much slower. Thermal desorption spectroscopy (TDS) results suggest CHT SAMs in UHV at RT can desorb more efficiently than HT SAMs due to formation of thiol desorption fragments that result from chemical reactions between surface hydrogen atoms and thiolates on Au(111) surfaces. This study clearly demonstrated that organic thiols chemisorbed on gold surfaces are desorbed spontaneously in UHV at RT and van der Waals interactions play an important role in determining the structural stability of thiolate SAMs in UHV. Copyright © 2012 Elsevier Inc. All rights reserved.

Glycogen synthase kinase-3 inhibition sensitizes human induced pluripotent stem cells to thiol-containing antioxidants induced apoptosis.

PubMed

Tu, Chengyi; Xu, Robert; Koleti, Meghana; Zoldan, Janet

2017-08-01

Inhibition of glycogen synthase kinase 3 (GSK3) is an extensively used strategy to activate Wnt pathway for pluripotent stem cell (PSC) differentiation. However, the effects of such inhibition on PSCs, besides upregulating the Wnt pathway, have rarely been investigated despite that GSK3 is broadly involved in other cellular activities such as insulin signaling and cell growth/survival regulation. Here we describe a previously unknown synergistic effect between GSK3 inhibition (e.g., Chir99021 and LY2090314) and various normally non-toxic thiol-containing antioxidants (e.g., N-acetylcysteine, NAC) on the induction of apoptosis in human induced pluripotent stem cells (iPSCs). Neither Chir99021 nor the antioxidants individually induced significant apoptosis, whereas their combined treatment resulted in rapid and extensive apoptosis, with substantial caspase 3 activity observed within 3h and over 90% decrease in cell viability after 24h. We confirmed the generality of this phenomenon with multiple independent iPSCs lines, various thiol-based antioxidants and distinct GSK3 inhibitors. Mechanistically, we demonstrated that rapamycin treatment could substantially reduce cell death, suggesting the critical role of mammalian target of rapamycin (mTOR). Akt dysregulation was also found to partially contribute to cell apoptosis but was not the primary cause. Further, this coordinated proapoptotic effect was not detected in mouse ESCs but was present in another human cells line: a breast cancer cell line (MDA-MB-231). Given the wide use of GSK3 inhibition in biomedical research: from iPSC differentiation to cancer intervention and the treatment of neuronal diseases, researchers can potentially take advantage of or avoid this synergistic effect for improved experimental or clinical outcome. Copyright © 2017. Published by Elsevier B.V.

Photoinitiated Bottom-Up Click Synthesis of Ion-Containing Networks as Hydroxide Exchange Membranes

NASA Astrophysics Data System (ADS)

Tibbits, Andrew Charles

Fuel cells are energy conversion devices which directly convert chemical energy into electrical energy and environmentally friendly byproducts (i.e., water) with potential versatility for transportation and portable applications. Hydroxide exchange membrane fuel cells (HEMFCs) have the potential to decrease the overall fuel cell cost through the utilization of non-precious metal catalysts such as nickel and silver as opposed to platinum which is used by the current standard technology, proton exchange membrane fuel cells (PEMFCs). However, substantial improvements in thermal and alkaline stability, hydroxide conductivity, mechanical flexibility, and processing are needed to create a competitive membrane for HEMFC applications. Regardless of the type of membrane, the high water uptake that is typically associated with increased ionic conductivity is problematic and can result in the dissolution of the membrane during fuel cell operation. Covalent crosslinking of the membrane is an approach which has been effectively applied to reduce water uptake without a significant compromise of the hydroxide conductivity. The synthesis and processing of membrane materials is vastly simplified by using click polymerization schemes. Click chemistry is a collection of organic chemical reactions that are rapid, selective, and high yielding. One of the most versatile and facile click reactions is the thiol-ene reaction, which is the radical-mediated addition reaction between a thiol (an -SH group) and an 'ene' (an electron rich vinyl group, C=C) in the presence of a photoinitiator and light. The click attributes of the thiol-ene reaction enables potential of "bottom-up" design of ion-containing polymers via a single step photoinitiated crosslinking reaction with precise control over structure and physicochemical properties not only for fuel cell membranes but also for a range of other applications including separations, sensors, flexible electronics, and coatings. However, a fundamental understanding of the formation and properties of ion-containing thiol-ene materials and their implementation as hydroxide exchange membranes is largely absent from the current literature. The work described herein will highlight the versatility of click reactions, primarily the thiol-ene reaction, for fabrication of ion-containing networks with tunable properties based on the rational design and synthesis of photopolymerizable ionic liquid comonomers with an emphasis on applicability for HEMFC applications. The role of ionic liquid monomer structure on the kinetics and mechanism of thiol-ene ionic network formation and the subsequent properties (i.e., ion conductive, thermomechanical, and structural) will be elucidated to establish a guided framework for click ionic material development. This framework will be directed onto the development of alkaline stable hydroxide-conductive membranes for fuel cell applications as well as the incorporation of catalytic nanoparticles into a photocrosslinkable formulation as a self-standing catalyst layer. Finally, novel approaches to membrane fabrication will be implemented to build on the foundational studies that will simultaneously enhance the ionic conductivity and mechanical properties of the ion-containing polymer materials: these approaches include the synthesis and crosslinking of photopolymerizable cationic surfactants for microphase separated membranes as well as the first "bottom-up" ion-containing polymer synthesized from the photoinitiated copper-catalyzed azide-alkyne cycloaddition (photo-CuAAC) reaction which exhibits enhanced processability and hydroxide conductivity (>50 mS/cm).

Depletion of Intracellular Thiols and Increased Production of 4-Hydroxynonenal that Occur During Cryopreservation of Stallion Spermatozoa Lead to Caspase Activation, Loss of Motility, and Cell Death.

PubMed

Martin Muñoz, Patricia; Ortega Ferrusola, Cristina; Vizuete, Guillermo; Plaza Dávila, Maria; Rodriguez Martinez, Heriberto; Peña, Fernando J

2015-12-01

Oxidative stress has been linked to sperm death and the accelerated senescence of cryopreserved spermatozoa. However, the molecular mechanisms behind this phenomenon remain poorly understood. Reactive oxygen species (ROS) are considered relevant signaling molecules for sperm function, only becoming detrimental when ROS homeostasis is lost. We hereby hypothesize that a major component of the alteration of ROS homeostasis in cryopreserved spermatozoa is the exhaustion of intrinsic antioxidant defense mechanisms. To test this hypothesis, semen from seven stallions was frozen using a standard technique. The parameters of sperm quality (motility, velocity, and membrane integrity) and markers of sperm senescence (caspase 3, 4-hydroxynonenal, and mitochondrial membrane potential) were assessed before and after cryopreservation. Changes in the intracellular thiol content were also monitored. Cryopreservation caused significant increases in senescence markers as well as dramatic depletion of intracellular thiols to less than half of the initial values (P < 0.001) postthaw. Interestingly, very high and positive correlations were observed among thiol levels with sperm functionality postthaw: total motility (r = 0.931, P < 0.001), progressive motility (r = 0.904, P < 0.001), and percentage of live spermatozoa without active caspase 3 (r = 0.996, P < 0.001). In contrast, negative correlations were detected between active caspase 3 and thiol content both in living (r = -0.896) and dead (r = -0.940) spermatozoa; additionally, 4-hydroxynonenal levels were negatively correlated with thiol levels (r = -0.856). In conclusion, sperm functionality postthaw correlates with the maintenance of adequate levels of intracellular thiols. The accelerated senescence of thawed spermatozoa is related to oxidative and electrophilic stress induced by increased production of 4-hydroxynoneal in thawed samples once intracellular thiols are depleted. © 2015 by the Society for the Study of Reproduction, Inc.

Self-organized fluorescent nanosensors for ratiometric Pb2+ detection.

PubMed

Arduini, Maria; Mancin, Fabrizio; Tecilla, Paolo; Tonellato, Umberto

2007-07-31

Silica nanoparticles (60 nm diameter) doped with fluorescent dyes and functionalized on the surface with thiol groups have been proved to be efficient fluorescent chemosensors for Pb2+ ions. The particles can detect a 1 microM metal ion concentration with a good selectivity, suffering only interference from Cu2+ ions. Analyte binding sites are provided by the simple grafting of the thiol groups on the nanoparticles. Once bound to the particles surface, the Pb2+ ions quench the emission of the reporting dyes embedded. Sensor performances can be improved by taking advantage of the ease of production of multishell silica particles. On one hand, signaling units can be concentrated in the external shells, allowing a closer interaction with the surface-bound analyte. On the other, a second dye can be buried in the particle core, far enough from the surface to be unaffected by the Pb2+ ions, thus producing a reference signal. In this way, a ratiometric system is easily prepared by simple self-organization of the particle components.

Adsorption kinetics of alkanethiol-capped gold nanoparticles at the hexane-water interface

NASA Astrophysics Data System (ADS)

Ferdous, Sultana; Ioannidis, Marios A.; Henneke, Dale

2011-12-01

The pendant drop technique was used to characterize the adsorption behavior of n-dodecane-1-thiol and n-hexane-1-thiol-capped gold nanoparticles at the hexane-water interface. The adsorption process was studied by analyzing the dynamic interfacial tension versus nanoparticle concentration, both at early times and at later stages (i.e., immediately after the interface between the fluids is made and once equilibrium has been established). A series of gold colloids were made using nanoparticles ranging in size from 1.60 to 2.85 nm dissolved in hexane for the interfacial tension analysis. Following free diffusion of nanoparticles from the bulk hexane phase, adsorption leads to ordering and rearrangement of the nanoparticles at the interface and formation of a dense monolayer. With increasing interfacial coverage, the diffusion-controlled adsorption for the nanoparticles at the interface was found to change to an interaction-controlled assembly and the presence of an adsorption barrier was experimentally verified. At the same bulk concentration, different sizes of n-dodecane-1-thiol nanoparticles showed different absorption behavior at the interface, in agreement with the findings of Kutuzov et al. (Phys Chem Chem Phys 9:6351-6358, 2007). The experiments additionally demonstrated the important role played by the capping agent. At the same concentration, gold nanoparticles stabilized by n-hexane-1-thiol exhibited greater surface activity than gold nanoparticles of the same size stabilized by n-dodecane-1-thiol. These findings contribute to the design of useful supra-colloidal structures by the self-assembly of alkane-thiol-capped gold nanoparticles at liquid-liquid interfaces.

Glutathione in Cancer Cell Death

PubMed Central

Ortega, Angel L.; Mena, Salvador; Estrela, Jose M.

2011-01-01

Glutathione (L-γ-glutamyl-L-cysteinyl-glycine; GSH) in cancer cells is particularly relevant in the regulation of carcinogenic mechanisms; sensitivity against cytotoxic drugs, ionizing radiations, and some cytokines; DNA synthesis; and cell proliferation and death. The intracellular thiol redox state (controlled by GSH) is one of the endogenous effectors involved in regulating the mitochondrial permeability transition pore complex and, in consequence, thiol oxidation can be a causal factor in the mitochondrion-based mechanism that leads to cell death. Nevertheless GSH depletion is a common feature not only of apoptosis but also of other types of cell death. Indeed rates of GSH synthesis and fluxes regulate its levels in cellular compartments, and potentially influence switches among different mechanisms of death. How changes in gene expression, post-translational modifications of proteins, and signaling cascades are implicated will be discussed. Furthermore, this review will finally analyze whether GSH depletion may facilitate cancer cell death under in vivo conditions, and how this can be applied to cancer therapy. PMID:24212662

Detoxification of toxins by bacillithiol in Staphylococcus aureus

PubMed Central

Newton, Gerald L.; Fahey, Robert C.

2012-01-01

Bacillithiol (BSH), an α-anomeric glycoside of l-cysteinyl-d-glucosaminyl-l-malate, is a major low-molecular-mass thiol found in bacteria such as Bacillus sp., Staphylococcus aureus and Deinococcus radiodurans. Like other low-molecular-mass thiols such as glutathione and mycothiol, BSH is likely to be involved in protection against environmental toxins including thiol-reactive antibiotics. We report here a BSH-dependent detoxification mechanism in S. aureus. When S. aureus Newman strain was treated with monobromobimane and monochlorobimane, the cellular BSH was converted to the fluorescent S-conjugate BS-bimane. A bacillithiol conjugate amidase activity acted upon the BS-bimane to produce Cys-bimane, which was then acetylated by an N-acetyltransferase to generate N-acetyl-Cys-bimane, a mercapturic acid. An S. aureus mutant lacking BSH did not produce mercapturic acid when treated with monobromobimane and monochlorobimane, confirming the involvement of bacillithiol. Furthermore, treatment of S. aureus Newman with rifamycin, the parent compound of the first-line anti-tuberculosis drug, rifampicin, indicated that this thiol-reactive antibiotic is also detoxified in a BSH-dependent manner, since mercapturic acids of rifamycin were observed in the culture medium. These data indicate that toxins and thiol-reactive antibiotics are detoxified to less potent mercapturic acids in a BSH-dependent manner and then exported out of the cell in S. aureus. PMID:22262099

Localization of ATP Sulfurylase and O-Acetylserine(thiol)lyase in Spinach Leaves.

PubMed

Lunn, J E; Droux, M; Martin, J; Douce, R

1990-11-01

The intracellular compartmentation of ATP sulfurylase and O-acetylserine(thiol)lyase in spinach (Spinacia oleracea L.) leaves has been investigated by isolation of organelles and fractionation of protoplasts. ATP sulfurylase is located predominantly in the chloroplasts, but is also present in the cytosol. No evidence was found for ATP sulfurylase activity in the mitochondria. Two forms of ATP sulfurylase were separated by anion-exchange chromatography. The more abundant form is present in the chloroplasts, the second is cytosolic. O-Acetylserine(thiol)lyase activity is located primarily in the chloroplasts and cytosol, but is also present in the mitochondria. Three forms of O-acetylserine(thiol)lyase were separated by anion-exchange chromatography, and each was found to be specific to one intracellular compartment. The cytosolic ATP sulfurylase may not be active in vivo due to the unfavorable equilibrium constant of the reaction, and the presence of micromolar concentrations of inorganic pyrophosphate in the cytosol, therefore its role remains unknown. It is suggested that the plant cell may be unable to transport cysteine between the different compartments, so that the cysteine required for protein synthesis must be synthesized in situ, hence the presence of O-acetylserine(thiol)lyase in the three compartments where proteins are synthesized.

Localization of ATP Sulfurylase and O-Acetylserine(thiol)lyase in Spinach Leaves

PubMed Central

Lunn, John E.; Droux, Michel; Martin, Jacqueline; Douce, Roland

1990-01-01

The intracellular compartmentation of ATP sulfurylase and O-acetylserine(thiol)lyase in spinach (Spinacia oleracea L.) leaves has been investigated by isolation of organelles and fractionation of protoplasts. ATP sulfurylase is located predominantly in the chloroplasts, but is also present in the cytosol. No evidence was found for ATP sulfurylase activity in the mitochondria. Two forms of ATP sulfurylase were separated by anion-exchange chromatography. The more abundant form is present in the chloroplasts, the second is cytosolic. O-Acetylserine(thiol)lyase activity is located primarily in the chloroplasts and cytosol, but is also present in the mitochondria. Three forms of O-acetylserine(thiol)lyase were separated by anion-exchange chromatography, and each was found to be specific to one intracellular compartment. The cytosolic ATP sulfurylase may not be active in vivo due to the unfavorable equilibrium constant of the reaction, and the presence of micromolar concentrations of inorganic pyrophosphate in the cytosol, therefore its role remains unknown. It is suggested that the plant cell may be unable to transport cysteine between the different compartments, so that the cysteine required for protein synthesis must be synthesized in situ, hence the presence of O-acetylserine(thiol)lyase in the three compartments where proteins are synthesized. PMID:16667839

Neuronal growth on L- and D-cysteine self-assembled monolayers reveals neuronal chiral sensitivity.

PubMed

Baranes, Koby; Moshe, Hagay; Alon, Noa; Schwartz, Shmulik; Shefi, Orit

2014-05-21

Studying the interaction between neuronal cells and chiral molecules is fundamental for the design of novel biomaterials and drugs. Chirality influences all biological processes that involve intermolecular interaction. One common method used to study cellular interactions with different enantiomeric targets is the use of chiral surfaces. Based on previous studies that demonstrated the importance of cysteine in the nervous system, we studied the effect of L- and D-cysteine on single neuronal growth. L-Cysteine, which normally functions as a neuromodulator or a neuroprotective antioxidant, causes damage at elevated levels, which may occur post trauma. In this study, we grew adult neurons in culture enriched with L- and D-cysteine as free compounds or as self-assembled monolayers of chiral surfaces and examined the effect on the neuronal morphology and adhesion. Notably, we have found that exposure to the L-cysteine enantiomer inhibited, and even prevented, neuronal attachment more severely than exposure to the D-cysteine enantiomer. Atop the L-cysteine surfaces, neuronal growth was reduced and degenerated. Since the cysteine molecules were attached to the surface via the thiol groups, the neuronal membrane was exposed to the molecular chiral site. Thus, our results have demonstrated high neuronal chiral sensitivity, revealing chiral surfaces as indirect regulators of neuronal cells and providing a reference for studying chiral drugs.

Redox sensing: Orthogonal control in cell cycle and apoptosis signaling

PubMed Central

Jones, Dean P.

2010-01-01

Living systems have three major types of cell signaling systems that are dependent upon high-energy chemicals, redox environment and transmembranal ion gating mechanisms. Development of integrated systems biology descriptions of cell signaling require conceptual models incorporating all three. Recent advances in redox biology show that thiol/disulfide redox systems are regulated under dynamic, non-equilibrium conditions, progressively oxidized with the life cycle of cells and distinct in terms of redox potentials among subcellular compartments. The present article uses these observations as a basis to distinguish “redox-sensing” mechanisms, which are more global biologic redox control mechanisms, from “redox signaling”, which involves conveyance of discrete activating or inactivating signals. Both redox sensing and redox signaling use sulfur switches, especially cysteine (Cys) residues in proteins which are sensitive to reversible oxidation, nitrosylation, glutathionylation, acylation, sulfhydration or metal binding. Unlike specific signaling mechanisms, the redox-sensing mechanisms provide means to globally affect the rates and activities of the high-energy, ion gating and redox-signaling systems by controlling sensitivity, distribution, macromolecular interactions and mobility of signaling proteins. Effects mediated through Cys residues not directly involved in signaling means redox-sensing control can be orthogonal to the signaling mechanisms. This provides a capability to integrate signals according to cell cycle and physiologic state without fundamentally altering the signaling mechanisms. Recent findings that thiol/disulfide pools in humans are oxidized with age, environmental exposures and disease risk suggest that redox-sensing thiols could provide a central mechanistic link in disease development and progression. PMID:20964735

A colorimetric and fluorescent probe for detecting intracellular biothiols.

PubMed

Chen, Chunyang; Liu, Wei; Xu, Cong; Liu, Weisheng

2016-11-15

A new rapid and highly sensitive coumarin-based probe (probe 1) has been designed and synthesized for detecting intracellular thiols. Probe 1 was prepared by a 4-step procedure as a latent fluorescence probe to achieve high sensitivity and fluorescence turn-on response toward cysteine and homocysteine over GSH and other various natural amino acids under physiological conditions. Owing to specific cyclization between thiols and aldehyde group, probe 1 displayed a highly selectivity toward cysteine and homocysteine. Above all, probe 1 was successfully used for fluorescence imaging of biothiols in Hela cells, and quantitative determination had been achieved within a certain range. Then specific fluorescence imaging of mice organ tissues was obtained for proving the permeability of probe 1. Simultaneously, the viability was measured to be more than 80%, which shows probe 1 can be a rapid and biocompatible probe for biothiols in cells. Furthermore, the measurement of thiols detection in 5 kinds of animal serum showed that probe 1 can be used in determination of biothiols in blood. Copyright © 2016 Elsevier B.V. All rights reserved.

Glutathione adducts on sarcoplasmic/endoplasmic reticulum Ca2+ ATPase Cys-674 regulate endothelial cell calcium stores and angiogenic function as well as promote ischemic blood flow recovery.

PubMed

Thompson, Melissa D; Mei, Yu; Weisbrod, Robert M; Silver, Marcy; Shukla, Praphulla C; Bolotina, Victoria M; Cohen, Richard A; Tong, Xiaoyong

2014-07-18

The sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA) is key to Ca(2+) homeostasis and is redox-regulated by reversible glutathione (GSH) adducts on the cysteine (C) 674 thiol that stimulate Ca(2+) uptake activity and endothelial cell angiogenic responses in vitro. We found that mouse hind limb muscle ischemia induced S-glutathione adducts on SERCA in both whole muscle tissue and endothelial cells. To determine the role of S-glutathiolation, we used a SERCA 2 C674S heterozygote knock-in (SKI) mouse lacking half the key thiol. Following hind limb ischemia, SKI animals had decreased SERCA S-glutathione adducts and impaired blood flow recovery. We studied SKI microvascular endothelial cells in which total SERCA 2 expression was unchanged. Cultured SKI microvascular endothelial cells showed impaired migration and network formation compared with wild type (WT). Ca(2+) studies showed decreased nitric oxide (·NO)-induced (45)Ca(2+) uptake into the endoplasmic reticulum (ER) of SKI cells, while Fura-2 studies revealed lower Ca(2+) stores and decreased vascular endothelial growth factor (VEGF)- and ·NO-induced Ca(2+) influx. Adenoviral overexpression of calreticulin, an ER Ca(2+) binding protein, increased ionomycin-releasable stores, VEGF-induced Ca(2+) influx and endothelial cell migration. Taken together, these data indicate that the redox-sensitive Cys-674 thiol on SERCA 2 is required for normal endothelial cell Ca(2+) homeostasis and ischemia-induced angiogenic responses, revealing a novel redox control of angiogenesis via Ca(2+) stores. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Nanostructured polymer brushes.

PubMed

Schmelmer, Ursula; Paul, Anne; Küller, Alexander; Steenackers, Marin; Ulman, Abraham; Grunze, Michael; Gölzhäuser, Armin; Jordan, Rainer

2007-03-01

Nanopatterned polymer brushes with sub-50-nm resolution were prepared by a combination of electron-beam chemical lithography (EBCL) of self-assembled monolayers (SAMs) and surface-initiated photopolymerization (SIPP). As a further development of our previous work, selective EBCL was performed with a highly focused electron beam and not via a mask, to region-selectively convert a SAM of 4'-nitro-1,1'-biphenyl-4-thiol to defined areas of crosslinked 4'-amino-1,1'-biphenyl-4-thiol. These "written" structures were then used to prepare surface-bonded, asymmetric, azo initiator sites of 4'-azomethylmalonodinitrile-1,1'-biphenyl-4-thiol. In the presence of bulk styrene, SIPP amplified the primary structures of line widths from 500 to 10 nm to polystyrene structures of line widths 530 nm down to approximately 45 nm at a brush height of 10 or 7 nm, respectively, as measured by scanning electron microscopy and atomic force microscopy (AFM). The relative position of individual structures was within a tolerance of a few nanometers, as verified by AFM. At line-to-line spacings down to 50-70 nm, individual polymer brush structures are still observable. Below this threshold, neighboring structures merge due to chain overlap.

Hydrogen Abstraction from Individual Thiophenol Molecules Adsorbed on Cu(111)

NASA Astrophysics Data System (ADS)

Rao, Bommisetty; Kwon, Ki-Young; Liu, Anwei; Zhang, Jin-Tao; Bartels, Ludwig

2004-03-01

Thiol compounds on metal surfaces have been studied intensively because of their ability to form self-assembled monolayers (SAMs). However, the transition from the thiol to the surface thiolate is difficult to investigate in detail in the solution phase. Here we report on STM measurements that address the adsorption of a variety of substituted thiophenols on Cu(111) at 15K in vacuum. At this temperature, adsorption does not cause immediate scission of the S-H bond. We confirmed this by STM-based vibrational spectroscopy. Consequently, the sulfur atom of the thiol group adsorbs on-top of a substrate atom, which results in a sufficient separation of the aryl group from the substrate to allow its free rotation even at 15K. Asymmetrically substituted thiophenols result in STM images of pronounced helicity, which indicates that the molecules cannot tilt upright to exchange their adsorption side. Attachment of electrons from the tunneling current can cause hydrogen abstraction from the thiophenols, which locks them into the substrate. We investigated the dependence of the yield of the hydrogen abstraction on the thiophenol substituent identity and position. We find pronounced variations which may follow the Hammett Equation known from Standard Organic Chemistry.

In situ surface-enhanced Raman scattering spectroscopy exploring molecular changes of drug-treated cancer cell nucleus.

PubMed

Liang, Lijia; Huang, Dianshuai; Wang, Hailong; Li, Haibo; Xu, Shuping; Chang, Yixin; Li, Hui; Yang, Ying-Wei; Liang, Chongyang; Xu, Weiqing

2015-02-17

Investigating the molecular changes of cancer cell nucleus with drugs treatment is crucial for the design of new anticancer drugs, the development of novel diagnostic strategies, and the advancement of cancer therapy efficiency. In order to better understand the action effects of drugs, accurate location and in situ acquisition of the molecular information of the cell nuclei are necessary. In this work, we report a microspectroscopic technique called dark-field and fluorescence coimaging assisted surface-enhanced Raman scattering (SERS) spectroscopy, combined with nuclear targeting nanoprobes, to in situ study Soma Gastric Cancer (SGC-7901) cell nuclei treated with two model drugs, e.g., DNA binder (Hoechst33342) and anticancer drug (doxorubicin, Dox) via spectral analysis at the molecular level. Nuclear targeting nanoprobes with an assembly structure of thiol-modified polyethylene glycol polymers (PEG) and nuclear localizing signal peptides (NLS) around gold nanorods (AuNRs) were prepared to achieve the amplified SERS signals of biomolecules in the cell nuclei. With the assistance of dark field/fluorescence imaging with simultaneous location, in situ SERS spectra in one cell nucleus were measured and analyzed to disclose the effects of Hoechst33342 and Dox on main biomolecules in the cell nuclei. The experimental results show that this method possesses great potential to investigate the targets of new anticancer drugs and the real-time monitoring of the dynamic changes of cells caused by exogenous molecules.

Low-Level Mercury Can Enhance Procoagulant Activity of Erythrocytes: A New Contributing Factor for Mercury-Related Thrombotic Disease

PubMed Central

Lim, Kyung-Min; Kim, Sujin; Noh, Ji-Yoon; Kim, Keunyoung; Jang, Won-Hee; Bae, Ok-Nam; Chung, Seung-Min; Chung, Jin-Ho

2010-01-01

Background Associations between cardiovascular diseases and mercury have been frequently described, but underlying mechanisms are poorly understood. Objectives We investigate the procoagulant activation of erythrocytes, an important contributor to thrombosis, by low-level mercury to explore the roles of erythrocytes in mercury-related cardiovascular diseases. Methods We used freshly isolated human erythrocytes and ex vivo and in vivo thrombosis models in rats to investigate mercury-induced procoagulant activity. Results Prolonged exposure to low-dose mercuric ion (Hg2+; 0.25–5 μM for 1–48 hr) induced erythrocyte shape changes from discocytes to echinocytes to spherocytes, accompanied by microvesicle (MV) generation. These MVs and remnant erythrocytes expressed phosphatidylserine (PS), an important mediator of procoagulant activation. Hg2+ inhibited flippase, an enzyme that recovers PS into the inner leaflet of the cell membrane, and activated scramblase, an enzyme that alters lipid asymmetry in the cell membrane. Consistent with these activity changes, Hg2+ increased intracellular calcium and depleted ATP and protein thiol. A thiol supplement reversed Hg2+-induced MV generation and PS exposure and inhibited the increase in calcium ion (Ca2+) and depletion of ATP, indicating that free-thiol depletion was critical to Hg2+-mediated procoagulant activity. The procoagulant activity of Hg2+-treated erythrocytes was demonstrated by increased thrombin generation and endothelial cell adhesion. We further confirmed Hg2+-mediated procoagulant activation of erythrocytes in ex vivo and in vivo rat thrombosis models, where Hg2+ treatment (0.5–2.5 mg/kg) increased PS exposure and thrombus formation significantly. Conclusion This study demonstrated that mercury could provoke procoagulant activity in erythrocytes through protein-thiol depletion–mediated PS exposure and MV generation, ultimately leading to enhanced thrombosis. PMID:20308036

Chloronitroimidazoles as radiosensitizers of hypoxic cells in vitro.

PubMed

Wideł, M; Watras, J; Suwiński, J; Salwińska, E

1987-01-01

Some results of the first more complex studies in vitro on radio-sensitizing efficiency, cytotoxicity and reactivity with blood-thiols of a series of 4- or 5-nitroimidazoles substituted in the 5, 4 or 2 position with chlorine are presented. The derivatives of 4-nitroimidazole substituted in 5 position ("ortho" position) with Cl show higher radiosensitizing efficiency than one may expect from their reduction potential, E1/2. At the same time they are extremely toxic, especially for aerobic cells. It is considered that high biological activity of ortho-substituted 4-nitroimidazoles is connected with their considerable chemical reactivity towards thiols and suppression of those natural protective compounds in the cells. The corresponding 5-nitro isomers are about tenfold weaker sensitizers, and simultaneously much less cytotoxic, either in aerobic or in hypoxic conditions. The chloro-4(5)-nitroimidazoles nonsubstituted at N-1 and ionizable in aqueous solution are relatively weaker at the same time less toxic radiosensitizers. It is evaluated that potential application in radiotherapy may have those chloronitroimidazoles which show low aerobic cytotoxicity, moderate radiosensitizing ability and no reactivity towards thiols. On the basis of the study in vitro, we have selected such a compound: 1-methyl-2-chloro-4-nitroimidazole (P13) for screening in vivo.

Self-assembled monolayers of alkyl-thiols on InAs: A Kelvin probe force microscopy study

NASA Astrophysics Data System (ADS)

Szwajca, A.; Wei, J.; Schukfeh, M. I.; Tornow, M.

2015-03-01

We report on the preparation and characterization of self-assembled monolayers from aliphatic thiols with different chain length and termination on InAs (100) planar surfaces. This included as first step the development and investigation of a thorough chemical InAs surface preparation step using a dedicated bromine/NH4OH-based etching process. Ellipsometry, contact angle measurements and atomic force microscopy (AFM) indicated the formation of smooth, surface conforming monolayers. The molecular tilt angles were obtained as 30 ± 10° with respect to the surface normal. Kelvin probe force microscopy (KPFM) measurements in hand with Parameterized Model number 5 (PM5) calculations of the involved molecular dipoles allowed for an estimation of the molecular packing densities on the surface. We obtained values of up to n = 1014 cm- 2 for the SAMs under study. These are close to what is predicted from a simple geometrical model that would calculate a maximum density of about n = 2.7 × 1014 cm- 2. We take this as additional conformation of the substrate smoothness and quality of our InAs-SAM hybrid layer systems.

Orthogonal chemical functionalization of patterned gold on silica surfaces

PubMed Central

Léonard, Didier; Le Mogne, Thierry; Zuttion, Francesca; Chevalier, Céline; Phaner-Goutorbe, Magali; Souteyrand, Éliane

2015-01-01

Summary Single-step orthogonal chemical functionalization procedures have been developed with patterned gold on silica surfaces. Different combinations of a silane and a thiol were simultaneously deposited on a gold/silica heterogeneous substrate. The orthogonality of the functionalization (i.e., selective grafting of the thiol on the gold areas and the silane on the silica) was demonstrated by X-ray photoelectron spectroscopy (XPS) as well as time-of-flight secondary ion mass spectrometry (ToF–SIMS) mapping. The orthogonal functionalization was used to immobilize proteins onto gold nanostructures on a silica substrate, as demonstrated by atomic force microscopy (AFM). These results are especially promising in the development of future biosensors where the selective anchoring of target molecules onto nanostructured transducers (e.g., nanoplasmonic biosensors) is a major challenge. PMID:26734519

Assembly of Oriented Virus Arrays by Chemo-Selective Ligation Methods and Nanolithography Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camarero, J A; Cheung, C L; Lin, T

2002-12-02

The present work describes our ongoing efforts towards the creation of nano-scaled ordered arrays of protein/virus covalently attached to site-specific chemical linkers patterned by different nanolithograpy techniques. We will present a new and efficient solid-phase approach for the synthesis of chemically modified long alkyl-thiols. These compounds can be used to introduce chemoselective reacting groups onto gold and silicon-based surfaces. Furthermore, these modified thiols have been used to create nanometric patterns by using different nanolithography techniques. We will show that these patterns can react chemoselectively with proteins and/or virus which have been chemically or recombinantly modified to contain complementary chemical groupsmore » at specific positions thus resulting in the oriented attachment of the protein or virus to the surface.« less

The use of a mercury biosensor to evaluate the bioavailability of mercury-thiol complexes and mechanisms of mercury uptake in bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ndu, Udonna; Barkay, Tamar; Mason, Robert P.

We discuss as mercury (Hg) biosensors are sensitive to only intracellular Hg, they are useful in the investigation of Hg uptake mechanisms and the effects of speciation on Hg bioavailability to microbes. In this study, bacterial biosensors were used to evaluate the roles that several transporters such as the glutathione, cystine/cysteine, and Mer transporters play in the uptake of Hg from Hg-thiol complexes by comparing uptake rates in strains with functioning transport systems to strains where these transporters had been knocked out by deletion of key genes. The Hg uptake into the biosensors was quantified based on the intracellular conversionmore » of inorganic mercury (Hg(II)) to elemental mercury (Hg(0)) by the enzyme MerA. It was found that uptake of Hg from Hg-cysteine (Hg(CYS) 2) and Hg-glutathione (Hg(GSH) 2) complexes occurred at the same rate as that of inorganic complexes of Hg(II) into Escherichia coli strains with and without intact Mer transport systems. However, higher rates of Hg uptake were observed in the strain with a functioning Mer transport system. These results demonstrate that thiol-bound Hg is bioavailable to E. coli and that this bioavailability is higher in Hg-resistant bacteria with a complete Mer system than in non-resistant strains. No difference in the uptake rate of Hg from Hg(GSH) 2 was observed in E. coli strains with or without functioning glutathione transport systems. There was also no difference in uptake rates between a wildtype Bacillus subtilis strain with a functioning cystine/cysteine transport system, and a mutant strain where this transport system had been knocked out. These results cast doubt on the viability of the hypothesis that the entire Hg-thiol complex is taken up into the cell by a thiol transporter. It is more likely that the Hg in the Hg-thiol complex is transferred to a transport protein on the cell membrane and is subsequently internalized.« less

The use of a mercury biosensor to evaluate the bioavailability of mercury-thiol complexes and mechanisms of mercury uptake in bacteria

DOE PAGES

Ndu, Udonna; Barkay, Tamar; Mason, Robert P.; ...

2015-09-15

We discuss as mercury (Hg) biosensors are sensitive to only intracellular Hg, they are useful in the investigation of Hg uptake mechanisms and the effects of speciation on Hg bioavailability to microbes. In this study, bacterial biosensors were used to evaluate the roles that several transporters such as the glutathione, cystine/cysteine, and Mer transporters play in the uptake of Hg from Hg-thiol complexes by comparing uptake rates in strains with functioning transport systems to strains where these transporters had been knocked out by deletion of key genes. The Hg uptake into the biosensors was quantified based on the intracellular conversionmore » of inorganic mercury (Hg(II)) to elemental mercury (Hg(0)) by the enzyme MerA. It was found that uptake of Hg from Hg-cysteine (Hg(CYS) 2) and Hg-glutathione (Hg(GSH) 2) complexes occurred at the same rate as that of inorganic complexes of Hg(II) into Escherichia coli strains with and without intact Mer transport systems. However, higher rates of Hg uptake were observed in the strain with a functioning Mer transport system. These results demonstrate that thiol-bound Hg is bioavailable to E. coli and that this bioavailability is higher in Hg-resistant bacteria with a complete Mer system than in non-resistant strains. No difference in the uptake rate of Hg from Hg(GSH) 2 was observed in E. coli strains with or without functioning glutathione transport systems. There was also no difference in uptake rates between a wildtype Bacillus subtilis strain with a functioning cystine/cysteine transport system, and a mutant strain where this transport system had been knocked out. These results cast doubt on the viability of the hypothesis that the entire Hg-thiol complex is taken up into the cell by a thiol transporter. It is more likely that the Hg in the Hg-thiol complex is transferred to a transport protein on the cell membrane and is subsequently internalized.« less

Polythiol-containing, recombinant mannosylated-albumin is a superior CD68+/CD206+ Kupffer cell-targeted nanoantioxidant for treatment of two acute hepatitis models.

PubMed

Maeda, Hitoshi; Hirata, Kenshiro; Watanabe, Hiroshi; Ishima, Yu; Chuang, Victor Tuan Giam; Taguchi, Kazuaki; Inatsu, Akihito; Kinoshita, Manabu; Tanaka, Motohiko; Sasaki, Yutaka; Otagiri, Masaki; Maruyama, Toru

2015-02-01

Since reactive oxygen species (ROS) derived from Kupffer cells (KC), especially CD68(+) KC, play a key role in the induction of hepatic oxidative stress and injuries, we developed a polythiolated- and mannosylated human serum albumin (SH-Man-HSA), which functions as a novel nanoantioxidant for delivering thiol to CD68(+) KC. In vitro electron paramagnetic resonance coupled with pharmacokinetics and immunohistochemical studies showed that SH-Man-HSA possessed powerful radical-scavenging activity and rapidly and selectively delivered thiols to the liver via mannose receptor (CD206) on CD68(+) cells. SH-Man-HSA significantly improved the survival rate of concanavalin-A (Con-A)-treated mice. Moreover, SH-Man-HSA exhibited excellent hepatoprotective functions, not by decreasing tumor necrosis factor or interferon-γ production that is closely associated with Con-A-induced hepatitis, but by suppressing ROS production. Interestingly, the protective effect of SH-Man-HSA was superior to N-acetyl cysteine (NAC). This could be attributed to the difference in the inhibition of hepatic oxidative stress between the two antioxidants depending on their potential for thiol delivery to the liver. Similar results were also observed for acetaminophen (APAP)-induced hepatopathy models. Flow cytometric data further confirmed that an increase in F4/80(+)/ROS(+) cells was dramatically decreased by SH-Man-HSA. The administration of SH-Man-HSA at 4 hours following a Con-A or APAP injection also exhibited a profound hepatoprotective action against these hepatitis models, whereas this was not observed for NAC. It can be concluded therefore that SH-Man-HSA has great potential for use in a rescue therapy for hepatopathy as a nanoantioxidant because of its ability to efficiently and rapidly deliver thiols to CD68(+)/CD206(+) KC. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Organic sulfur compounds resulting from the interaction of iron sulfide, hydrogen sulfide and carbon dioxide in an anaerobic aqueous environment

NASA Astrophysics Data System (ADS)

Heinen, Wolfgang; Lauwers, Anne Marie

1996-04-01

The reaction of iron sulfide (FeS) with H2S in water, in presence of CO2 under anaerobic conditions was found to yield H2 and a variety of organic sulfur compounds, mainly thiols and small amounts of CS2 and dimethyldisulfide. The same compounds were produced when H2S was replaced by HCl, in the H2S-generating system FeS/HCl/CO2. The identification of the products was confirmed by GC-MS analyses and the incorporation of H2 in the organic sulfur compounds was demonstrated by experiments in which all hydrogen compounds were replaced by deuterium compounds. Generation of H2 and the synthesis of thiols were both dependent upon the relative abundance of FeS and HCl or H2S, i.e. the FeS/HCl- or FeS/H2S-proportions. Whether thiols or CS2 were formed as the main products depended also on the FeS/HCl-ratio: All conditions which create a H2 deficiency were found to initiate a proportional increase in the amount of CS2. The quantities of H2 and thiols generated depended on temperature: the production of H2 was significantly accelerated from 50°C onward and thiol synthesis above 75°C. The yield of thiols increased with the amount of FeS and HCl (H2S), given a certain FeS/HCl-ratio and a surplus of CO2. A deficiency of CO2 results in lower thiol systhesis. The end product, pyrite (FeS2), was found to appear as a silvery granular layer floating on the aqueous surface. The identity of the thiols was confirmed by mass spectrometry, and the reduction of CO2 demonstrated by the determination of deuterium incorporation with DCl and D2O. The described reactions can principally proceed under the conditions comparable to those obtaining around submarine hydrothermal vents, or the global situation about 4 billion years ago, before the dawn of life, and could replace the need for a reducing atmosphere on the primitive earth.

Diselenolane-mediated cellular uptake.

PubMed

Chuard, Nicolas; Poblador-Bahamonde, Amalia I; Zong, Lili; Bartolami, Eline; Hildebrandt, Jana; Weigand, Wolfgang; Sakai, Naomi; Matile, Stefan

2018-02-21

The emerging power of thiol-mediated uptake with strained disulfides called for a move from sulfur to selenium. We report that according to results with fluorescent model substrates, cellular uptake with 1,2-diselenolanes exceeds uptake with 1,2-dithiolanes and epidithiodiketopiperazines with regard to efficiency as well as intracellular localization. The diselenide analog of lipoic acid performs best. This 1,2-diselenolane delivers fluorophores efficiently to the cytosol of HeLa Kyoto cells, without detectable endosomal capture as with 1,2-dithiolanes or dominant escape into the nucleus as with epidithiodiketopiperazines. Diselenolane-mediated cytosolic delivery is non-toxic (MTT assay), sensitive to temperature but insensitive to inhibitors of endocytosis (chlorpromazine, methyl-β-cyclodextrin, wortmannin, cytochalasin B) and conventional thiol-mediated uptake (Ellman's reagent), and to serum. Selenophilicity, the extreme CSeSeC dihedral angle of 0° and the high but different acidity of primary and secondary selenols might all contribute to uptake. Thiol-exchange affinity chromatography is introduced as operational mimic of thiol-mediated uptake that provides, in combination with rate enhancement of DTT oxidation, direct experimental evidence for existence and nature of the involved selenosulfides.

Jacks of metal/metalloid chelation trade in plants—an overview

PubMed Central

Anjum, Naser A.; Hasanuzzaman, Mirza; Hossain, Mohammad A.; Thangavel, Palaniswamy; Roychoudhury, Aryadeep; Gill, Sarvajeet S.; Rodrigo, Miguel A. Merlos; Adam, Vojtěch; Fujita, Masayuki; Kizek, Rene; Duarte, Armando C.; Pereira, Eduarda; Ahmad, Iqbal

2015-01-01

Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loid)s (hereafter termed as “metal/s”) mainly through anthropogenic activities. These metals may contaminate food chain and bring irreparable consequences in human. Plant-based approach (phytoremediation) stands second to none among bioremediation technologies meant for sustainable cleanup of soils/sites with metal-contamination. In turn, the capacity of plants to tolerate potential consequences caused by the extracted/accumulated metals decides the effectiveness and success of phytoremediation system. Chelation is among the potential mechanisms that largely govern metal-tolerance in plant cells by maintaining low concentrations of free metals in cytoplasm. Metal-chelation can be performed by compounds of both thiol origin (such as GSH, glutathione; PCs, phytochelatins; MTs, metallothioneins) and non-thiol origin (such as histidine, nicotianamine, organic acids). This paper presents an appraisal of recent reports on both thiol and non-thiol compounds in an effort to shed light on the significance of these compounds in plant-metal tolerance, as well as to provide scientific clues for the advancement of metal-phytoextraction strategies. PMID:25883598

Enhanced Adsorption of Trivalent Arsenic from Water by Functionalized Diatom Silica Shells

PubMed Central

Zhang, Zhijian; Xu, Liping; Zhang, Chunlong

2015-01-01

The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino) groups to effectively remove arsenic in its toxic As(III) form (arsenite) predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III) concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III) at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III) adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film) and internal (intraparticle) diffusion can be rate-determining for As(III) adsorption. Fourier transform infrared spectroscopy (FTIR) indicated that the thiol and amino groups potentially responsible for As(III) adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS) further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III) and thiol groups, and through the surface complexation between As(III) and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III) adsorption capacity holds promise for the treatment of As(III) containing wastewater. PMID:25837498

Bis(N'-{(E)-[(2E)-1,3-di-phenyl-prop-2-en-1-yl-idene]amino}-N-ethyl-carbamimido-thio-ato-κ2N',S)zinc(II): crystal structure and Hirshfeld surface analysis.

PubMed

Tan, Ming Yueh; Crouse, Karen A; Ravoof, Thahira B S A; Jotani, Mukesh M; Tiekink, Edward R T

2017-07-01

The title Zn II complex, [Zn(C 18 H 18 N 3 S) 2 ], (I), features two independent but chemically equivalent mol-ecules in the asymmetric unit. In each, the thio-semicarbazonate monoanion coordinates the Zn II atom via the thiol-ate-S and imine-N atoms, with the resulting N 2 S 2 donor set defining a distorted tetra-hedral geometry. The five-membered ZnSCN 2 chelate rings adopt distinct conformations in each independent mol-ecule, i.e. one ring is almost planar while the other is twisted about the Zn-S bond. In the crystal, the two mol-ecules comprising the asymmetric unit are linked by amine-N-H⋯N(imine) and amine-N-H⋯S(thiol-ate) hydrogen bonds via an eight-membered heterosynthon, {⋯HNCN⋯HNCS}. The dimeric aggregates are further consolidated by benzene-C-H⋯S(thiol-ate) inter-actions and are linked into a zigzag supra-molecular chain along the c axis via amine-N-H⋯S(thiol-ate) hydrogen bonds. The chains are connected into a three-dimensional architecture via phenyl-C-H⋯π(phen-yl) and π-π inter-actions, the latter occurring between chelate and phenyl rings [inter-centroid separation = 3.6873 (11) Å]. The analysis of the Hirshfeld surfaces calculated for (I) emphasizes the different inter-actions formed by the independent mol-ecules in the crystal and the impact of the π-π inter-actions between chelate and phenyl rings.

Nanoparticle-Based Receptors Mimic Protein-Ligand Recognition.

PubMed

Riccardi, Laura; Gabrielli, Luca; Sun, Xiaohuan; De Biasi, Federico; Rastrelli, Federico; Mancin, Fabrizio; De Vivo, Marco

2017-07-13

The self-assembly of a monolayer of ligands on the surface of noble-metal nanoparticles dictates the fundamental nanoparticle's behavior and its functionality. In this combined computational-experimental study, we analyze the structure, organization, and dynamics of functionalized coating thiols in monolayer-protected gold nanoparticles (AuNPs). We explain how functionalized coating thiols self-organize through a delicate and somehow counterintuitive balance of interactions within the monolayer itself and with the solvent. We further describe how the nature and plasticity of these interactions modulate nanoparticle-based chemosensing. Importantly, we found that self-organization of coating thiols can induce the formation of binding pockets in AuNPs. These transient cavities can accommodate small molecules, mimicking protein-ligand recognition, which could explain the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. Thus, our findings advocate for the rational design of tailored coating groups to form specific recognition binding sites on monolayer-protected AuNPs.

Thiol Modification of Psyllium Husk Mucilage and Evaluation of Its Mucoadhesive Applications

PubMed Central

Bhatia, Meenakshi

2013-01-01

Thiol functionalization of psyllium was carried out to enhance its mucoadhesive potential. Thiolation of psyllium was achieved by esterification with thioglycolic acid. Thiolation was observed to change the surface morphology of psyllium from fibrous to granular and result in a slight increase in the crystallinity and swelling. Thiolated psyllium was found to contain 3.282 m moles of thiol groups/g of the polymer. Mucoadhesive applications of thiolated psylium were explored by formulating gels using metronidazole as the model drug. On comparative evaluation thiolated psyllium gels showed 3-fold higher mucoadhesive strength than the psyllium gels as determined by modified physical balance using chicken buccal pouch. The results of in vitro release study revealed that thiolated psyllium gels provided a prolonged release of metronidazole. Further, the psyllium and thiolated psyllium gels were found to release the drug following first-order kinetics by combination of polymer relaxation and diffusion through the matrix. PMID:24348147

Anticancer activity of drug conjugates in head and neck cancer cells.

PubMed

Majumdar, Debatosh; Rahman, Mohammad Aminur; Chen, Zhuo Georgia; Shin, Dong M

2016-06-01

Sexually transmitted oral cancer/head and neck cancer is increasing rapidly. Human papilloma virus (HPV) is playing a role in the pathogenesis of a subset of squamous cell carcinoma of head and neck (SCCHN). Paclitaxel is a widely used anticancer drug for breast, ovarian, testicular, cervical, non-small cell lung, head and neck cancer. However, it is water insoluble and orally inactive. We report the synthesis of water soluble nanosize conjugates of paclitaxel, branched PEG, and EGFR-targeting peptide by employing native chemical ligation. We performed a native chemical ligation between the N-hydroxy succinimide (NHS) ester of paclitaxel succinate and cysteine at pH 6.5 to give the cysteine-conjugated paclitaxel derivative. The thiol functionality of cysteine was activated and subsequently conjugated to multiarm thiol-PEG to obtain the paclitaxel branched PEG conjugate. Finally, we conjugated an EGFR-targeting peptide to obtain conjugates of paclitaxel, branched PEG, and EGFR-targeting peptide. These conjugates show anticancer activity against squamous cell carcinoma of head and neck cells (SCCHN, Tu212).

Collateral Sensitivity of Multidrug-Resistant Cells to the Orphan Drug Tiopronin

PubMed Central

Goldsborough, Andrew S.; Handley, Misty D.; Dulcey, Andrés E.; Pluchino, Kristen M.; Kannan, Pavitra; Brimacombe, Kyle R.; Hall, Matthew D.; Griffiths, Gary; Gottesman, Michael M.

2011-01-01

A major challenge in the treatment of cancer is multidrug resistance (MDR) that develops during chemotherapy. Here we demonstrate that tiopronin (1), a thiol-substituted N-propanoylglycine derivative, was selectively toxic to a series of cell lines expressing the drug efflux pump P-glycoprotein (P-gp, ABCB1) and MRP1 (ABCC1). Treatment of MDR cells with 1 led to instability of the ABCB1 mRNA and consequently a reduction in P-gp protein, despite functional assays demonstrating that tiopronin does not interact with P-gp. Long-term exposure of P-gp-expressing cells to 1 sensitized them to doxorubicin and taxol, both P-gp substrates. Treatment of MRP1-overexpressing cells with tiopronin led to a significant reduction in MRP1 protein. Synthesis and screening of analogs of tiopronin demonstrated that the thiol functional group was essential for collateral sensitivity, while substitution of the amino acid backbone altered but did not destroy specificity, pointing to future development of targeted analogs. PMID:21657271

Local Delivery of Gene Vectors From Bare-Metal Stents by Use of a Biodegradable Synthetic Complex Inhibits In-Stent Restenosis in Rat Carotid Arteries

PubMed Central

Fishbein, Ilia; Alferiev, Ivan; Bakay, Marina; Stachelek, Stanley J.; Sobolewski, Peter; Lai, Meizan; Choi, Hoon; Chen, I.-W.; Levy, Robert J.

2012-01-01

Background Local drug delivery from polymer-coated stents has demonstrated efficacy for preventing in-stent restenosis; however, both the inflammatory effects of polymer coatings and concerns about late outcomes of drug-eluting stent use indicate the need to investigate innovative approaches, such as combining localized gene therapy with stent angioplasty. Thus, we investigated the hypothesis that adenoviral vectors (Ad) could be delivered from the bare-metal surfaces of stents with a synthetic complex for reversible vector binding. Methods and Results We synthesized the 3 components of a gene vector binding complex: (1) A polyallylamine bisphosphonate with latent thiol groups (PABT), (2) a polyethyleneimine (PEI) with pyridyldithio groups for amplification of attachment sites [PEI(PDT)], and (3) a bifunctional (amine- and thiol-reactive) cross-linker with a labile ester bond (HL). HL-modified Ad attached to PABT/PEI(PDT)-treated steel surfaces demonstrated both sustained release in vitro over 30 days and localized green fluorescent protein expression in rat arterial smooth muscle cell cultures, which were not sensitive to either inhibition by neutralizing anti-Ad antibodies or inactivation after storage at 37°C. In rat carotid studies, deployment of steel stents configured with PABT/PEI(PDT)/HL-tethered adenoviral vectors demonstrated both site-specific arterial AdGFP expression and adenovirus-luciferase transgene activity per optical imaging. Rat carotid stent delivery of adenovirus encoding inducible nitric oxide synthase resulted in significant inhibition of restenosis. Conclusions Reversible immobilization of adenovirus vectors on the bare-metal surfaces of endovascular stents via a synthetic complex represents an efficient, tunable method for sustained release of gene vectors to the vasculature. PMID:18413497

Thiol antioxidant-functionalized CdSe/ZnS quantum dots: Synthesis, Characterization, Cytotoxicity

PubMed Central

Zheng, Hong; Mortensen, Luke J.; DeLouise, Lisa A.

2016-01-01

Nanotechnology is a growing industry with wide ranging applications in consumer product and technology development. In the biomedical field, nanoparticles are finding increasing use as imaging agents for biomolecular labeling and tumor targeting. The nanoparticle physiochemical properties must be tailored for the specific application but chemical and physical stability in the biological milieu (no oxidation, aggregation, agglomeration or toxicity) are often required. Nanoparticles used for biomolecular fluorescent imaging should also have high quantum yield (QY). The aim of this paper is to examine the QY, stability, and cell toxicity of a series of positive, negative and neutral surface charge quantum dot (QD) nanoparticles. Simple protocols are described to prepare water soluble QDs by modifying the surface with thiol containing antioxidant ligands and polymers keeping the QD core/shell composition constant. The ligands used to produce negatively charged QDs include glutathione (GSH), N-acetyl-L-cysteine (NAC), dihydrolipoic acid (DHLA), tiopronin (TP), bucilliamine (BUC), and mercaptosuccinic acid (MSA). Ligands used to produce positively charged QDs include cysteamine (CYS) and polyethylenimine (PEI). Dithiothreitol (DTT) was used to produce neutral charged QDs. Commercially available nonaqueous octadecylamine (ODA) capped QDs served as the starting material. Our results suggest that QD uptake and cytotoxicity are both dependent on surface ligand coating composition. The negative charged GSH coated QDs show superior performance exhibiting low cytotoxicity, high stability, high QY and therefore are best suited for bioimaging applications. PEI coated QD also show superior performance exhibiting high QY and stability. However, they are considerably more cytotoxic due to their high positive charge which is an advantageous property that can be exploited for gene transfection and/or tumor targeting applications. The synthetic procedures described are straightforward and can be easily adapted in most laboratory settings. PMID:23620993

Evaluation of fracture toughness and mechanical properties of ternary thiol-ene-methacrylate systems as resin matrix for dental restorative composites.

PubMed

Beigi, Saeed; Yeganeh, Hamid; Atai, Mohammad

2013-07-01

Study and evaluation of fracture toughness, flexural and dynamic mechanical properties, and crosslink density of ternary thiol-ene-methacrylate systems and comparison with corresponding conventional methacrylate system were considered in the present study. Urethane tetra allyl ether monomer (UTAE) was synthesized as ene monomer. Different formulations were prepared based on combination of UTAE, BisGMA/TEGDMA and a tetrathiol monomer (PETMP). The photocuring reaction was conducted under visible light using BD/CQ combination as photoinitiator system. Mechanical properties were evaluated via measuring flexural strength, flexural modulus and fracture toughness. Scanning electron microscopy (SEM) was utilized to study the morphology of the fractured specimen's cross section. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). The same study was performed on a conventional methacrylate system. The data were analyzed and compared by ANOVA and Tukey HSD tests (significance level=0.05). The results showed improvement in fracture toughness of the specimens containing thiol-ene moieties. DMTA revealed a lower glass transition temperature and more homogenous structure for thiol-ene containing specimens in comparison to the system containing merely methacrylate monomer. The flexural modulus and flexural strength of the specimens with higher thiol-ene content were lower than the neat methacrylate system. The SEM micrographs of the fractured surface of specimens with higher methacrylate content were smooth and mirror-like (shiny) which represent brittle fracture. The thiol-ene-methacrylate system can be used as resin matrix of dental composites with enhanced fracture toughness in comparison to the methacrylate analogous. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Acetate- and thiol-capped monodisperse ruthenium nanoparticles: XPS, XAS, and HRTEM studies.

PubMed

Chakroune, Nassira; Viau, Guillaume; Ammar, Souad; Poul, Laurence; Veautier, Delphine; Chehimi, Mohamed M; Mangeney, Claire; Villain, Françoise; Fiévet, Fernand

2005-07-19

Monodisperse ruthenium nanoparticles were prepared by reduction of RuCl3 in 1,2-propanediol. The mean particle size was controlled by appropriate choice of the reduction temperature and the acetate ion concentration. Colloidal solutions in toluene were obtained by coating the metal particles with dodecanethiol. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XANES and EXAFS for the Ru K-absorption edge) were performed on particles of two different diameters, 2 and 4 nm, and in different environments, polyol/acetate or thiol. For particles stored in polyol/acetate XPS studies revealed superficial oxidation limited to one monolayer and a surface coating containing mostly acetate ions. Analysis of the EXAFS spectra showed both oxygen and ruthenium atoms around the ruthenium atoms with a Ru-Ru coordination number N smaller than the bulk value, as expected for fine particles. In the case of 2 nm acetate-capped particles N is consistent with particles made up of a metallic core and an oxidized monolayer. For 2 nm thiol-coated particles, a Ru-S bond was evidenced by XPS and XAS. For the 4 nm particles XANES and XPS studies showed that most of the ruthenium atoms are in the zerovalent state. Nevertheless, in both cases, when capped with thiol, the Ru-Ru coordination number inferred from EXAFS is much smaller than for particles of the same size stored in polyol. This is attributed to a structural disorganization of the particles by thiol chemisorption. HRTEM studies confirm the marked dependence of the structural properties of the ruthenium particles on their chemical environment; they show the acetate-coated particles to be single crystals, whereas the thiol-coated particles appear to be polycrystalline.

Immobilization of Protein A on SAMs for the elaboration of immunosensors.

PubMed

Briand, Elisabeth; Salmain, Michèle; Compère, Chantal; Pradier, Claire-Marie

2006-12-01

Binary mixtures of 11-mercaptoundecanoic acid (MUA) and other thiols of various lengths and terminal functions were chemisorbed on gold-coated surfaces via S-Au bonds to form mixed self-assembled monolayers (SAMs). Several values of the mole fraction of MUA in the thiol mixtures were tested and the structure and composition of the resulted thin films were characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The results made it clear that co-adsorption of MUA with thiols of similar chain length led to well-ordered monolayers whereas the co-adsorption of MUA with shorter thiols yielded less crystalline-like thin films, but with more reactive carboxylic acid terminal groups. This criterion appeared decisive for efficient covalent binding of Staphylococcus aureus Protein A (PrA), a protein that displays high affinity for the constant fragment (Fc) of antibodies of the IgG type from various mammal species. The ability of immobilized Protein A to recognize and bind a model IgG appeared to be optimal for the mixed SAM of MUA and the short-chain, omega-hydroxythiol 6-mercaptohexanol in the proportion 1-3.

Vapor-liquid interfacial reaction to fabricate superhydrophilic and underwater superoleophobic thiol-ene/silica hybrid decorated fabric for oil/water separation

NASA Astrophysics Data System (ADS)

Li, Hongqiang; Liang, Tao; Lai, Xuejun; Su, Xiaojing; Zhang, Lin; Zeng, Xingrong

2018-01-01

With oil spill accidents and oil industrial wastewater increasing, oil/water separation has attracted much attention in recent years. Herein, we report the fabrication of superhydrophilic and underwater superoleophobic thiol-ene/silica hybrid decorated fabrics for oil/water separation via vapor-liquid interfacial reaction. It is based on sol-gel reaction of tetraethyl orthosilicate (TEOS) to generate silica and thiol-ene reaction between poly(ethylene glycol) dimethacrylate (PEGDMA) and trimethylolpropane tris(3-mercaptopropionate) (TTMP) to form crosslinked hydrophilic polymer on polyester fabric under the catalysis of butylamine/ammonia vapor. The chemical structure of the surfaces on thiol-ene/silica hybrid decorated fabric was confirmed by FTIR and XPS, and obvious micro-nano morphology and roughness were observed with SEM and AFM. The water contact angle of the fabric attained 0° in 0.36 s, and the underwater oil contact angle reached up to 160°. Importantly, the fabric exhibited high separation efficiency at 99.5%, fast water flux above 71600 Lm-2h-1 and excellent recyclability in oil/water separation. Our findings open a new strategy to fabricate organic-inorganic hybrid superhydrophobic and underwater superoleophobic materials for oil/water separation.

The effect of Au amount on size uniformity of self-assembled Au nanoparticles

NASA Astrophysics Data System (ADS)

Chen, S.-H.; Wang, D.-C.; Chen, G.-Y.; Chen, K.-Y.

2008-03-01

The self-assembled fabrication of nanostructure, a dreaming approach in the area of fabrication engineering, is the ultimate goal of this research. A finding was proved through previous research that the size of the self-assembled gold nanoparticles could be controlled with the mole ratio between AuCl4- and thiol. In this study, the moles of Au were fixed, only the moles of thiol were adjusted. Five different mole ratios of Au/S with their effect on size uniformity were investigated. The mole ratios were 1:1/16, 1:1/8, 1:1, 1:8, 1:16, respectively. The size distributions of the gold nanoparticles were analyzed by Mac-View analysis software. HR-TEM was used to derive images of self-assembled gold nanoparticles. The result reached was also the higher the mole ratio between AuCl4- and thiol the bigger the self-assembled gold nanoparticles. Under the condition of moles of Au fixed, the most homogeneous nanoparticles in size distribution derived with the mole ratio of 1:1/8 between AuCl4- and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

Investigation of thiol-disulphide balance in patients with acute urticaria and chronic spontaneous urticaria.

PubMed

Akbas, Ayse; Kilinc, Fadime; Sener, Sertac; Aktaş, Akın; Baran, Pervin; Ergin, Merve

2017-09-01

Thiol-disulphide balance plays a major role in health and diseases. This balance may be disrupted by various diseases. We aimed to determine status of the effect of thiol-disulphide balance in urticaria. We aimed to investigate the thiol-disulphide balance in patients with acute urticaria (AUP) and chronic spontaneous urticaria (CSU). Study included 53 AUP and 47 healthy controls plus 57 patients with chronic spontaneous urticaria (CSUP) and 57 healthy controls. Levels of native thiols, disulphides and total thiols were evaluated in plasma using a new and automated spectrophotometric method. Ratios of disulphides/total thiols, disulphides/native thiols and native thiols/total thiols were calculated. For AU, there was no statistical difference compared to control group in levels of native thiols, disulphides and total thiols. For CSU, however, there was an increase in levels of native thiols, disulphides and total thiols and the ratio of thiol/disulphide in favour of disulphide. Thiol-disulphide balance was not affected by AU but shifted towards to disulphide in CSU indicating the presence of oxidative stress (OS).

Studies of benzamide- and thiol-based histone deacetylase inhibitors in models of oxidative-stress-induced neuronal death: identification of some HDAC3-selective inhibitors.

PubMed

Chen, Yufeng; He, Rong; Chen, Yihua; D'Annibale, Melissa A; Langley, Brett; Kozikowski, Alan P

2009-05-01

We compare three structurally different classes of histone deacetylase (HDAC) inhibitors that contain benzamide, hydroxamate, or thiol groups as the zinc binding group (ZBG) for their ability to protect cortical neurons in culture from cell death induced by oxidative stress. This study reveals that none of the benzamide-based HDAC inhibitors (HDACIs) provides any neuroprotection whatsoever, in distinct contrast to HDACIs that contain other ZBGs. Some of the sulfur-containing HDACIs, namely the thiols, thioesters, and disulfides present modest neuroprotective activity but show toxicity at higher concentrations. Taken together, these data demonstrate that the HDAC6-selective mercaptoacetamides that were reported previously provide the best protection in the homocysteic acid model of oxidative stress, thus further supporting their study in animal models of neurodegenerative diseases.

Electron beam-induced graft polymerization of acrylic acid and immobilization of arginine-glycine-aspartic acid-containing peptide onto nanopatterned polycaprolactone.

PubMed

Sun, Hui; Wirsén, Anders; Albertsson, Ann-Christine

2004-01-01

Electron beam- (EB-) induced graft polymerization of acrylic acid and the subsequent immobilization of arginine-glycine-aspartic acid (RGD) peptide onto nanopatterned polycaprolactone with parallel grooves is reported. A high concentration of carboxylic groups was introduced onto the polymer substrate by EB-induced polymerization of acrylic acid. In the coupling of the RGD peptide to the carboxylated polymer surface, a three-step peptide immobilization process was used. This process included the activation of surface carboxylic acid into an active ester intermediate by use of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), the introduction of disulfide groups by use of 2-(2-pyridinyldithio)ethanamine hydrochloride (PDEA), and final immobilization of the peptide via a thiol-disulfide exchange reaction. The extent of coupling was measured by UV spectroscopy. A preliminary study of the in vitro behavior of keratinocytes (NCTC 2544) cultured on the acrylic acid-grafted and RGD peptide-coupled surface showed that most cells grown on the coupled samples had a spread-rounded appearance, while the majority of cells tended to be elongated along the grooves on uncoupled substrates.

Thiol Reactivity of Curcumin and Its Oxidation Products.

PubMed

Luis, Paula B; Boeglin, William E; Schneider, Claus

2018-04-16

The polypharmacological effects of the turmeric compound curcumin may be partly mediated by covalent adduction to cellular protein. Covalent binding to small molecule and protein thiols is thought to occur through a Michael-type addition at the enone moiety of the heptadienedione chain connecting the two methoxyphenol rings of curcumin. Here we show that curcumin forms the predicted thiol-Michael adducts with three model thiols, glutathione, N-acetylcysteine, and β-mercaptoethanol. More abundant, however, are respective thiol adducts of the dioxygenated spiroepoxide intermediate of curcumin autoxidation. Two electrophilic sites at the quinone-like ring of the spiroepoxide are identified. Addition of β-mercaptoethanol at the 5'-position of the ring gives a 1,7-dihydroxycyclopentadione-5' thioether, and addition at the 1'-position results in cleavage of the aromatic ring from the molecule, forming methoxyphenol-thioether and a tentatively identified cyclopentadione aldehyde. The curcuminoids demethoxy- and bisdemethoxycurcumin do not form all of the possible thioether adducts, corresponding with their increased stability toward autoxidation. RAW264.7 macrophage-like cells activated with phorbol ester form curcumin-glutathionyl and the 1,7-dihydroxycyclopentadione-5'-glutathionyl adducts. These studies indicate that the enone of the parent compound is not the only functional electrophile in curcumin, and that its oxidation products provide additional electrophilic sites. This suggests that protein binding by curcumin may involve oxidative activation into reactive quinone methide and spiroepoxide electrophiles.

Protoapigenone, a natural derivative of apigenin, induces mitogen-activated protein kinase-dependent apoptosis in human breast cancer cells associated with induction of oxidative stress and inhibition of glutathione S-transferase π.

PubMed

Chen, Wen-Ying; Hsieh, Yu-An; Tsai, Ching-I; Kang, Ya-Fei; Chang, Fang-Rong; Wu, Yang-Chang; Wu, Chin-Chung

2011-12-01

Protoapigenone, a natural derivative of the flavonoid apigenin, has been shown to exhibit potent antitumor activity in vitro and in vivo; the precise mechanism of action, however, is not fully elucidated. In this study, we investigated and compared the mechanisms by which protoapigenone and apigenin caused cell death in the human breast cancer MDA-MB-231 cells. Flow cytometry analysis revealed that protoapigenone induced apoptosis with 10-fold greater potency than apigenin. Cancer cells treated with protoapigenone resulted in persistent activation of mitogen-activated protein kinase (MAPK) ERK, JNK, and p38, hyperphosphorylation of Bcl-2 and Bcl-xL, and loss of mitochondrial membrane potential (MMP). The MAPK inhibitors effectively prevented the loss of MMP and apoptosis induced by protoapigenone. Treatment of cells with protoapigenone led to increased levels of reactive oxygen species (ROS) and decreased levels of intracellular glutathione. The thiol-antioxidant N-acetylcysteine abolished protoapigenone-induced MAPK activation, mitochondrial dysfunction, and apoptosis. These results suggest that the induction of oxidative stress preceding the activation of MAPK is required to initiate the mitochondria-mediated apoptosis induced by protoapigenone. Additionally, protoapigenone-induced JNK activation was linked to thiol modification of glutathione S-transferase π (GSTpi), which impeded GSTpi inhibition of JNK. In contrast to protoapigenone, apigenin-induced apoptosis was neither dependent on ROS nor on MAPK. Structure-activity relationship studies suggested that the thiol reacting effect of protoapigenone might be associated with an α, β-unsaturated ketone moiety in the structure of ring B.

Nanosilver - does it have only one face?

PubMed

Likus, Wirginia; Bajor, Grzegorz; Siemianowicz, Krzysztof

2013-01-01

Silver nanoparticles (NPs) have at least one dimension of a particle smaller than 100 nm and contain 20-15,000 silver atoms. Due to its antibacterial activity nanosilver (NS) is used for medical purposes. NS particles can be obtained by various methods. Potentially, the best method of the NS synthesis for medical purposes is based on a brief flow of electric current between two silver electrodes placed in deionized water. It is accepted that the major antibacterial effect of silver is its partial oxidation and releasing silver ions, which interact with thiol groups of peptidoglicans of bacterial cell wall, and proteins of the cell membrane causing cell lysis. Silver ions can also bind to bacterial DNA preventing its replication and stopping synthesis of bacterial proteins. The rise in exposure to silver NPs has spurred interest into their toxicology. NS undergoes a set of biochemical transformations including accelerated oxidative dissolution in gastric acid, binding to thiol groups of serum and tissue proteins, exchange between thiol groups, sulfides and selenides, binding to selenoproroteins and photoreduction in skin to zerovalent metallic silver. Animal studies have shown that exposure to NS may lead to liver and spleen damage. NS can also stimulate an increased secretion of proinflammatory cytokines by monocytes. As a spectrum of NS applications is still growing, the complex evaluation of a safety of its use becomes an important task. This requires an elucidation of not only the influence of NS on human cells and organism, but also its biotransformation in organism and in environment.

Electrochemical and spectroscopic characterization of surface sol-gel processes.

PubMed

Chen, Xiaohong; Wilson, George S

2004-09-28

(3-Mercaptopropyl)trimethoxysilane (MTS) forms a unique film on a platinum substrate by self-assembly and sol-gel cross-linking. The gelating and drying states of the self-assembled MTS sol-gel films were probed by use of electrochemical and spectroscopic methods. The thiol moiety was the only active group within the sol-gel network. Gold nanoparticles were employed to detect the availability of the thiol group and their interaction further indicated the physicochemical states of the sol-gel inner structure. It was found that the thiol groups in the open porous MTS aerogel matrix were accessible to the gold nanoparticles while thiol groups in the compact MTS xerogel network were not accessible to the gold nanoparticles. The characteristics of the sol-gel matrix change with time because of its own irreversible gelating and drying process. The present work provides direct evidence of gold nanoparticle binding with thiol groups within the sol-gel structures and explains the different permeability of "aerogel" and "xerogel" films of MTS on the basis of electrochemical and spectroscopic results. Two endogenous species, hydrogen peroxide and ascorbic acid, were used to test the permeability of the self-assembled sol-gel film in different states. The MTS xerogel film on the platinum electrode was extremely selective against ascorbic acid while maintaining high sensitivity to hydrogen peroxide in contrast to the relatively high permeability of ascorbic acid in the MTS aerogel film. This study showed the potential of the MTS sol-gel film as a nanoporous material in biosensor development.

Reactivities of some thiol collectors and their interactions with Ag (+1) ion by molecular modeling

NASA Astrophysics Data System (ADS)

Yekeler, Hulya; Yekeler, Meftuni

2004-09-01

The most commonly used collectors for sulfide minerals in the mining industry are the thiol collectors for the recovery of these minerals from their associated gangues by froth flotation. For this reason, a great deal of attention has been paid to understand the attachment mechanism of thiol collectors to metal sulfide surfaces. The density functional theory (DFT) calculations at the B3LYP/3-21G* and B3LYP/6-31++G** levels were employed to propose the flotation responses of these thiol collectors, namely, diethyl dithiocarbamate, ethyl dithiocarbamate, ethyl dithiocarbonate, ethyl trithiocarbonate and ethyl dithiophosphate ions, and to study the interaction energies of these collectors with Ag (+1) ion in connection to acanthite (Ag 2S) mineral. The calculated interaction energies, Δ E, were interpreted in terms of the highest occupied molecular orbital (HOMO) energies of the isolated collector ions. The results show that the HOMOs are strongly localized to the sulfur atoms and the HOMO energies can be used as a reactivity descriptor for the flotation ability of the thiol collectors. Using the HOMO and Δ E energies, the reactivity order of the collectors is found to be (C 2H 5) 2NCS 2- > C 2H 5NHCS 2- > C 2H 5OCS 2- > C 2H 5SCS 2- > (C 2H 5O)(OH)PS 2-. The theoretically obtained results are in good agreement with the experimental data reported.

Flower-like self-assembly of gold nanoparticles for highly sensitive electrochemical detection of chromium(VI)

PubMed Central

Ouyang, Ruizhuo; Bragg, Stefanie A.; Chambers, James Q.; Xue, Zi-Ling

2012-01-01

We report here the fabrication of a flower-like self-assembly of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) as a highly sensitive platform for ultratrace Cr(VI) detection. Two AuNPs layers are used in the current approach, in which the first is electroplated on the GCE surface as anchors for binding to an overcoated thiol sol-gel film derived from 3-mercaptopropyltrimethoxysilane (MPTS). The second AuNPs layer is then self-assembled on the surface of the sol-gel film, forming flower-like gold nanoelectrodes enlarging the electrode surface. When functionalized by a thiol pyridinium, the fabricated electrode displays a well-defined peak for selective Cr(VI) reduction with an unusually large, linear concentration range of 10–1,200 ng L−1 and a low detection limit of 2.9 ng L−1. In comparison to previous approaches using MPTS and AuNPs on Au electrodes, the current work expands the use of AuNPs to the GCE. Subsequent functionalization of the secondary AuNPs by a thiol pyridinium and adsorption/preconcentration of Cr(VI) lead to the unusually large detection range and high sensitivity. The stepwise preparation of the electrode has been characterized by electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM), and IR. The newly designed electrode exhibits good stability, and has been successfully employed to measure chromium in a pre-treated blood sample. The method demonstrates acceptable fabrication reproducibility and accuracy. PMID:22444528

PDMS-co-PVMS Copolymer Synthesis for Microfluidic Devices

NASA Astrophysics Data System (ADS)

Baiamonte, Arissa; Nguyen, Devin; Lwoya, Baraka; Kelly, Giovanni; Albert, Julie N. L.

Poly (dimethylsiloxane) (PDMS) is the predominant material used for the fabrication of microfluidic devices because it is an easily synthesized, biocompatible, and flexible material that forms a good seal with other surfaces. However, PDMS is chemically inert and therefore difficult to functionalize for targeted applications, it can swell in the presence of organic solvents, and it can contaminate microfluidic solutions with unreacted oligomers. Therefore, my research goal is to synthesize random copolymers of PDMS and poly (vinylmethylsiloxane) (PVMS) that retain the benefits of PDMS and can be functionalized easily via thiol-ene click reactions. In the first stage of this work, dichlorodimethylsilane and vinylmethyldichlorosilane were each reacted with water to produce n-membered dimethylsiloxane rings and n-membered vinylmethylsiloxane rings, respectively. In the next step, polymers are synthesized by reacting these rings with potassium hydroxide and heat to form PDMS, PVMS, and PDMS-co-PVMS copolymers. Several reaction conditions have been tested to determine the kinetics and to relate molecular weight of the polymer or copolymer to reaction time. The polymer is then cross-liked through hydroxyl end groups with vinylmethoxysiloxane homopolymer (PVMES) cross-linker, tin catalyst, and heat. Once the polymer is cross-linked, the surface can be modified via thiol-ene click reaction to provide a diversity of surface functionality for microfluidic device applications. In the present work, we functionalize with a fluorinated thiol to impart solvent resistance. Newcomb Tulane College Georges Lurcy Grant, National Academies Gulf Research Program Early Career Research Fellowship, Tulane CIF.

Engineering of Surface Chemistry for Enhanced Sensitivity in Nanoporous Interferometric Sensing Platforms.

PubMed

Law, Cheryl Suwen; Sylvia, Georgina M; Nemati, Madieh; Yu, Jingxian; Losic, Dusan; Abell, Andrew D; Santos, Abel

2017-03-15

We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au 3+ ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.

d-Fructose-Decorated Poly(ethylene imine) for Human Breast Cancer Cell Targeting.

PubMed

Englert, Christoph; Pröhl, Michael; Czaplewska, Justyna A; Fritzsche, Carolin; Preußger, Elisabeth; Schubert, Ulrich S; Traeger, Anja; Gottschaldt, Michael

2017-08-01

The high affinity of GLUT5 transporter for d-fructose in breast cancer cells has been discussed intensely. In this contribution, high molar mass linear poly(ethylene imine) (LPEI) is functionalized with d-fructose moieties to combine the selectivity for the GLUT5 transporter with the delivery potential of PEI for genetic material. The four-step synthesis of a thiol-group bearing d-fructose enables the decoration of a cationic polymer backbone with d-fructose via thiol-ene photoaddition. The functionalization of LPEI is confirmed by 2D NMR techniques, elemental analysis, and size exclusion chromatography. Importantly, a d-fructose decoration of 16% renders the polymers water-soluble and eliminates the cytotoxicity of PEI in noncancer L929 cells, accompanied by a reduced unspecific cellular uptake of the genetic material. In contrast, the cytotoxicity as well as the cell specific uptake is increased for triple negative MDA-MB-231 breast cancer cells. Therefore, the introduction of d-fructose shows superior potential for cell targeting, which can be assumed to be GLUT5 dependent. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bio-inspired hydrophobic modification of cellulose nanocrystals with castor oil.

PubMed

Shang, Qianqian; Liu, Chengguo; Hu, Yun; Jia, Puyou; Hu, Lihong; Zhou, Yonghong

2018-07-01

This work presents an efficient and environmentally friendly approach to generate hydrophobic cellulose nanocrystals (CNC) using thiol-containing castor oil (CO-SH) as a renewable hydrophobe with the assist of bio-inspired dopamine at room temperature. The modification process included the formation of the polydopamine (PDA) buffer layer on CNC surfaces and the Michael addition reaction between the catechol moieties of PDA coating and thiol groups of CO-SH. The morphology, crystalline structure, surface chemistry, thermal stability and hydrophobicity of the modified CNC were charactered by TEM, XRD, FT-IR, solid-state 13 C NMR, XPS, TGA and contact angle analysis. The modified CNC preserved cellulose crystallinity, displayed higher thermal stability than unmodified CNC, and was highly hydrophobic with a water contact angle of 95.6°. The simplicity and versatility of the surface modification strategy inspired by adhesive protein of mussel may promote rapid development of hydrophobic bio-based nanomaterials for various applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Materials from Mussel-Inspired Chemistry for Cell and Tissue Engineering Applications.

PubMed

Madhurakkat Perikamana, Sajeesh Kumar; Lee, Jinkyu; Lee, Yu Bin; Shin, Young Min; Lee, Esther J; Mikos, Antonios G; Shin, Heungsoo

2015-09-14

Current advances in biomaterial fabrication techniques have broadened their application in different realms of biomedical engineering, spanning from drug delivery to tissue engineering. The success of biomaterials depends highly on the ability to modulate cell and tissue responses, including cell adhesion, as well as induction of repair and immune processes. Thus, most recent approaches in the field have concentrated on functionalizing biomaterials with different biomolecules intended to evoke cell- and tissue-specific reactions. Marine mussels produce mussel adhesive proteins (MAPs), which help them strongly attach to different surfaces, even under wet conditions in the ocean. Inspired by mussel adhesiveness, scientists discovered that dopamine undergoes self-polymerization at alkaline conditions. This reaction provides a universal coating for metals, polymers, and ceramics, regardless of their chemical and physical properties. Furthermore, this polymerized layer is enriched with catechol groups that enable immobilization of primary amine or thiol-based biomolecules via a simple dipping process. Herein, this review explores the versatile surface modification techniques that have recently been exploited in tissue engineering and summarizes polydopamine polymerization mechanisms, coating process parameters, and effects on substrate properties. A brief discussion of polydopamine-based reactions in the context of engineering various tissue types, including bone, blood vessels, cartilage, nerves, and muscle, is also provided.

A Gravity-Responsive Time-Keeping Protein of the Plant and Animal Cell Surface

NASA Technical Reports Server (NTRS)

Morre, D. James

2003-01-01

The hypothesis under investigation was that a ubiquinol (NADH) oxidase protein of the cell surface with protein disulfide-thiol interchange activity (= NOX protein) is a plant and animal time-keeping ultradian (period of less than 24 h) driver of both cell enlargement and the biological clock that responds to gravity. Despite considerable work in a large number of laboratories spanning several decades, this is, to my knowledge, our work is the first demonstration of a time-keeping biochemical reaction that is both gravity-responsive and growth-related and that has been shown to determine circadian periodicity. As such, the NOX protein may represent both the long-sought biological gravity receptor and the core oscillator of the cellular biological clock. Completed studies have resulted in 12 publications and two issued NASA-owned patents of the clock activity. The gravity response and autoentrainment were characterized in cultured mammalian cells and in two plant systems together with entrainment by light and small molecules (melatonin). The molecular basis of the oscillatory behavior was investigated using spectroscopic methods (Fourier transform infrared and circular dichroism) and high resolution electron microscopy. We have also applied these findings to an understanding of the response to hypergravity. Statistical methods for analysis of time series phenomena were developed (Foster et al., 2003).

Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging.

PubMed

Li, Jiuxing; Zhu, Zhi; Zhu, Bingqing; Ma, Yanli; Lin, Bingqian; Liu, Rudi; Song, Yanling; Lin, Hui; Tu, Song; Yang, Chaoyong

2016-08-02

Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging.

Reactivation of oxidized PTP1B and PTEN by Thioredoxin 1

PubMed Central

Schwertassek, Ulla; Haque, Aftabul; Krishnan, Navasona; Greiner, Romy; Weingarten, Lars; Dick, Tobias P.; Tonks, Nicholas K.

2014-01-01

The transient inactivation of protein phosphatases contributes to the efficiency and temporal control of kinase-dependent signal transduction. In particular, members of the protein tyrosine phosphatase family are known to undergo reversible oxidation of their active site cysteine. The thiol oxidation step requires activation of co-localized NADPH oxidases and is mediated by locally produced ROS, in particular H2O2. How oxidized phosphatases are returned to the reduced active state is less well studied. Both major thiol reductive systems, the thioredoxin and the glutathione systems, have been implicated in the reactivation of phosphatases. Here, we show that the protein tyrosine phosphatase PTP1B and the dual-specificity phosphatase PTEN are preferentially reactivated by the thioredoxin system. We show that inducible depletion of TRX1 slows down PTEN re-activation in intact living cells. Finally, using a mechanism-based trapping approach we demonstrate direct thiol disulfide exchange between the active sites of thioredoxin and either phosphatase. The application of thioredoxin trapping mutants represents a complementary approach to direct assays of PTP oxidation in elucidating the significance of redox regulation of PTP function in the control of cell signaling. PMID:24976139

Modulating the physicochemical and structural properties of gold-functionalized protein nanotubes through thiol surface modification.

PubMed

Carreño-Fuentes, Liliana; Plascencia-Villa, Germán; Palomares, Laura A; Moya, Sergio E; Ramírez, Octavio T

2014-12-16

Biomolecules are advantageous scaffolds for the synthesis and ordering of metallic nanoparticles. Rotavirus VP6 nanotubes possess intrinsic affinity to metal ions, a property that has been exploited to synthesize gold nanoparticles over them. The resulting nanobiomaterials have unique properties useful for novel applications. However, the formed nanobiomaterials lack of colloidal stability and flocculate, limiting their functionality. Here we demonstrate that it is possible to synthesize thiol-protected gold nanoparticles over VP6 nanotubes, which resulted in soluble nanobiomaterials. With this strategy, it was possible to modulate the size, colloidal stability, and surface plasmon resonance of the synthesized nanoparticles by controlling the content of the thiolated ligands. Two types of water-soluble ligands were tested, a small linear ligand, sodium 3-mercapto-1-propanesulfonate (MPS), and a bulky ligand, 5-mercaptopentyl β-D-glucopyranoside (GlcC5SH). The synthesized nanobiomaterials had a higher stability in suspension, as determined by Z-potential measurements. To the extent of our knowledge, this is the first time that a rational strategy is developed to modulate the particular properties of metal nanoparticles in situ synthesized over a protein bioscaffold through thiol coating, achieving a high spatial and structural organization of nanoparticles in a single integrative hybrid structure.

Reducing Agent-Assisted Excessive Galvanic Replacement Mediated Seed-Mediated Synthesis of Porous Gold Nanoplates and Highly Efficient Gene-Thermo Cancer Therapy.

PubMed

Kang, Seounghun; Kang, Kyunglee; Huh, Hyun; Kim, Hyungjun; Chang, Sung-Jin; Park, Tae Jung; Chang, Ki Soo; Min, Dal-Hee; Jang, Hongje

2017-10-11

Porous Au nanoplates (pAuNPs) were manufactured by a reducing agent-assisted galvanic replacement reaction on Ag nanoplates using a seed-mediated synthetic approach. Two core additives, poly(vinylpyrrolidone) and l-ascorbic acid, prevented fragmentation and proceeded secondary growth. By controlling the concentration of the additives and the amount of replacing ion AuCl 4 - , various nanostructures including nanoplates with holes, nanoframes, porous nanoplates, and bumpy nanoparticles with unity and homogeneity were synthesized. The present synthetic method is advantageous, because it can be used to manufacture pAuNPs with ease, robustness, and convenience. The prepared pAuNPs exhibited a highly efficient photothermal conversion effect and cargo loading capacity on exposed surfaces by Au-thiol linkage. By using dual cargo mixed loading of the hepatitis C virus (HCV) targeting gene drug DNAzyme and cell-penetrating peptide TAT onto the surface of the pAuNPs and photothermal conversion-mediated hyperthermic treatment, successful gene-thermo therapy against HCV genomic human hepatocarcinoma cells were demonstrated.

A novel electrochemical biosensor based on polyadenine modified aptamer for label-free and ultrasensitive detection of human breast cancer cells.

PubMed

Wang, Kun; He, Meng-Qi; Zhai, Fu-Heng; He, Rong-Huan; Yu, Yong-Liang

2017-05-01

Simple, rapid, sensitive, and specific detection of cancer cells plays a pivotal role in the diagnosis and prognosis of cancer. A sandwich electrochemical biosensor was developed based on polyadenine (polydA)-aptamer modified gold electrode (GE) and polydA-aptamer functionalized gold nanoparticles/graphene oxide (AuNPs/GO) hybrid for the label-free and selective detection of breast cancer cells (MCF-7) via a differential pulse voltammetry (DPV) technique. Due to the intrinsic affinity between multiple consecutive adenines of polydA sequences and gold, polydA modified aptamer instead of thiol terminated aptamer was immobilized on the surface of GE and AuNPs/GO. The label-free MCF-7 cells could be recognized by polydA-aptamer and self-assembled onto the surface of GE. The polydA-aptamer functionalized AuNPs/GO hybrid could further bind to MCF-7 cells to form a sandwich sensing system. Characterization of the surface modified GE was carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using Fe(CN) 6 3-/4- as a redox probe. Under the optimized experimental conditions, a detection limit of 8 cellsmL -1 (3σ/slope) was obtained for MCF-7 cells by the present electrochemical biosensor, along with a linear range of 10-10 5 cellsmL -1 . By virtue of excellent sensitivity, specificity and repeatability, the present electrochemical biosensor provides a potential application in point-of-care cancer diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

From petal effect to lotus effect: a facile solution immersion process for the fabrication of super-hydrophobic surfaces with controlled adhesion.

PubMed

Cheng, Zhongjun; Du, Ming; Lai, Hua; Zhang, Naiqing; Sun, Kening

2013-04-07

In this paper, a convenient approach based on the reaction between an alkyl thiol and hierarchical structured Cu(OH)2 substrates is reported for the fabrication of super-hydrophobic surfaces with controlled adhesion. This reaction can etch the Cu(OH)2 microstructures and simultaneously introduce a coating with low surface energy. By simply controlling the reaction time or the chain length of the thiol, super-hydrophobic surfaces with controlled adhesion can be achieved, and the adhesive force between the surface and the water droplet can be adjusted from extreme low (∼14 μN) to very high (∼65 μN). The tunable effect of the adhesion is ascribed to the different wetting states for the droplet on the surface that results from the change of the morphology and microstructure scale after the thiolate reaction. Noticeably, the as-prepared surfaces are acid/alkali-resisting; the acidic and basic water droplets have similar contact angles and adhesive forces to that of the neutral water droplet. Moreover, we demonstrate a proof of water droplet transportation for application in droplet-based microreactors via our surfaces. We believe that the results reported here would be helpful for the further understanding of the effect of wetting states on the surface adhesion and the fabrication principle for a super-hydrophobic surface with controlled adhesion.

Electrochemical and in vitro neuronal recording characteristics of multi-electrode arrays surface-modified with electro-co-deposited gold-platinum nanoparticles.

PubMed

Kim, Yong Hee; Kim, Ah Young; Kim, Gook Hwa; Han, Young Hwan; Chung, Myung-Ae; Jung, Sang-Don

2016-02-01

In order to complement the high impedance electrical property of gold nanoparticles (Au NPs) we have performed electro-co-deposition of gold-platinum nanoparticles (Au-Pt NPs) onto the Au multi-electrode array (MEA) and modified the Au-Pt NPs surface with cell adhesive poly-D-lysine via thiol chemistry based covalent binding. The Au-Pt NPs were analyzed to have bimetallic nature not the mixture of Au NPs and Pt NPs by X-ray diffraction analysis and to have impedance value (4.0 × 10(4) Ω (at 1 kHz)) comparable to that of Pt NPs. The performance of Au-Pt NP-modified MEAs was also checked in relation to neuronal signal recording. The noise level in Au-Pt NP-modified MEAs was lower than in that of Au NP-modified MEA.

Dinitrosyl iron complexes and S-nitrosothiols are two possible forms for stabilization and transport of nitric oxide in biological systems.

PubMed

Vanin, A F

1998-07-01

The physicochemical properties, mechanisms of synthesis and decomposition of dinitrosyl iron complexes (DNICs) with thiol-containing ligands and of S-nitrosothiols (RS-NO), and the potential role of these compounds in storage and transport of NO in biological systems are reviewed. Special attention is given to the phenomenon of mutual transformation of DNIC and RS-NO catalyzed by Fe2+. Each Fe2+ binds two neutral NO molecules in the DNICs, catalyzes their mutual oxidation--reduction with formation of nitrous oxide and nitrosonium ions appearing in the DNICs. These ions S-nitrosate thiol-compounds with RS-NO formation. Fe2+ binds two RS-NO molecules and catalyzes their mutual oxidation--reduction followed by decomposition of the resulting molecules. Mutual conversion of DNICs and RS-NO regulated by iron, thiol, and NO levels is suggested to provide NO transport in cells and tissues.

Resin-assisted Enrichment of N-terminal Peptides for Characterizing Proteolytic Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jong Seo; Dai, Ziyu; Aryal, Uma K.

2013-06-17

Proteolytic processing is a ubiquitous, irreversible posttranslational modification that plays an important role in cellular regulation in all living organisms. Herein we report a resin-assisted positive selection method for specifically enriching protein N-terminal peptides to facilitate the characterization of proteolytic processing events by liquid chromatography-tandem mass spectrometry. In this approach, proteins are initially reduced and alkylated and their lysine residues are converted to homoarginines. Then, protein N-termini are selectively converted to reactive thiol groups. We demonstrate that these sequential reactions were achieved with nearly quantitative efficiencies. Thiol-containing N-terminal peptides are then captured (>98% efficiency) by a thiol-affinity resin, a significantmore » improvement over the traditional avidin/biotin enrichment. Application to cell lysates of Aspergillus niger, a filamentous fungus of interest for biomass degradation, enabled the identification of 1672 unique protein N-termini and proteolytic cleavage sites from 690 unique proteins.« less

The basics of thiols and cysteines in redox biology and chemistry.

PubMed

Poole, Leslie B

2015-03-01

Cysteine is one of the least abundant amino acids, yet it is frequently found as a highly conserved residue within functional (regulatory, catalytic, or binding) sites in proteins. It is the unique chemistry of the thiol or thiolate group of cysteine that imparts to functional sites their specialized properties (e.g., nucleophilicity, high-affinity metal binding, and/or ability to form disulfide bonds). Highlighted in this review are some of the basic biophysical and biochemical properties of cysteine groups and the equations that apply to them, particularly with respect to pKa and redox potential. Also summarized are the types of low-molecular-weight thiols present in high concentrations in most cells, as well as the ways in which modifications of cysteinyl residues can impart or regulate molecular functions important to cellular processes, including signal transduction. Copyright © 2014 Elsevier Inc. All rights reserved.

Imaging thiol redox status in murine tumors in vivo with rapid-scan electron paramagnetic resonance

NASA Astrophysics Data System (ADS)

Epel, Boris; Sundramoorthy, Subramanian V.; Krzykawska-Serda, Martyna; Maggio, Matthew C.; Tseytlin, Mark; Eaton, Gareth R.; Eaton, Sandra S.; Rosen, Gerald M.; Kao, Joseph P. Y.; Halpern, Howard J.

2017-03-01

Thiol redox status is an important physiologic parameter that affects the success or failure of cancer treatment. Rapid scan electron paramagnetic resonance (RS EPR) is a novel technique that has shown higher signal-to-noise ratio than conventional continuous-wave EPR in in vitro studies. Here we used RS EPR to acquire rapid three-dimensional images of the thiol redox status of tumors in living mice. This work presents, for the first time, in vivo RS EPR images of the kinetics of the reaction of 2H,15N-substituted disulfide-linked dinitroxide (PxSSPx) spin probe with intracellular glutathione. The cleavage rate is proportional to the intracellular glutathione concentration. Feasibility was demonstrated in a FSa fibrosarcoma tumor model in C3H mice. Similar to other in vivo and cell model studies, decreasing intracellular glutathione concentration by treating mice with L-buthionine sulfoximine (BSO) markedly altered the kinetic images.

Solvent polarity effect on quality of n-octadecanethiol self-assembled monolayers on copper and oxidized copper

NASA Astrophysics Data System (ADS)

Zhang, Yaozhong; Zhou, Jun; Zhang, Xiaoli; Hu, Jun; Gao, Han

2014-11-01

This article reports the effect of solvent polarity on the formation of n-octadecanethiol self-assembled monolayers (C18SH-SAMs) on pure copper surface and oxidized copper surface. The quality of SAMs prepared in different solvents (n-hexane, toluene, trichloroethylene, chloroform, acetone, acetonitrile, ethanol) was monitored by EIS, RAIRS and XPS. The results indicated that C18SH-SAMs formed in these solvents were in good barrier properties on pure copper surface and the structures of monolayers formed in high polarity solvents were more compact and orderly than that formed in low polarity solvents. For comparison, C18SH adsorbed on the surface of oxidized copper in these solvents were studied and the results indicated that C18SH could be adsorbed on oxidized copper surface after the reduction of copper oxide layer by thiols. Compared with high polarity solvents, a limited reduction process of oxidized copper by thiols led to the incompletely formation of monolayers in low polarity solvents. This can be interpreted that the generated water on solid-liquid interface and a smaller reaction force restrict the continuous reduction reaction in low polarity solvents

Thiol/disulphide homeostasis in celiac disease

PubMed Central

Kaplan, Mustafa; Ates, Ihsan; Yuksel, Mahmut; Ozderin Ozin, Yasemin; Alisik, Murat; Erel, Ozcan; Kayacetin, Ertugrul

2017-01-01

AIM To determine dynamic thiol/disulphide homeostasis in celiac disease and to examine the associate with celiac autoantibodies and gluten-free diet. METHODS Seventy three patients with celiac disease and 73 healthy volunteers were enrolled in the study. In both groups, thiol/disulphide homeostasis was examined with a new colorimetric method recently developed by Erel and Neselioglu. RESULTS In patients with celiac disease, native thiol (P = 0.027) and total thiol (P = 0.031) levels were lower, while disulphide (P < 0.001) level, disulphide/native thiol (P < 0.001) and disulphide/total thiol (P < 0.001) ratios were higher compared to the control group. In patients who do not comply with a gluten-free diet, disulphide/native thiol ratio was found higher compared to the patients who comply with the diet (P < 0.001). In patients with any autoantibody-positive, disulphide/native thiol ratio was observed higher compared to the patients with autoantibody-negative (P < 0.05). It is found that there is a negative correlation between celiac autoantibodies, and native thiol, total thiol levels and native thiol/total thiol ratio, while a positive correlation is observed between disulphide, disulphide/native thiol and disulphide/total thiol levels. CONCLUSION This study is first in the literature which found that the patients with celiac disease the dynamic thiol/disulphide balance shifts through disulphide form compared to the control group. PMID:28533921

S-protected thiolated hydroxyethyl cellulose (HEC): Novel mucoadhesive excipient with improved stability.

PubMed

Leonaviciute, Gintare; Bonengel, Sonja; Mahmood, Arshad; Ahmad Idrees, Muneeb; Bernkop-Schnürch, Andreas

2016-06-25

The aim of this study was the design of novel S-protected thiolated hydroxyethyl cellulose (HEC) and the assessment of its mucoadhesive properties and biodegradability compared to the corresponding unmodified polymer. Thiolated HEC was S-protected via disulfide bond formation between 6-mercaptonicotinamide (6-MNA) and the thiol substructures of the polymer. In vitro screening of mucoadhesive properties was accomplished using two different methods: rotating cylinder studies and viscosity measurements. Moreover, biodegradability of these polymers by cellulase, xylanase and lysozyme was evaluated. MTT and LDH assays were performed on Caco-2 cells to determine the cytotoxicity of S-protected thiolated HEC. Thiolated HEC displayed 280.09±1.70μmol of free thiol groups per gram polymer. S-protected thiolated HEC exhibiting 270.8±21.11μmol immobilized 6-MNA ligands per gram of polymer was shown being 2.4-fold more mucoadhesive compared to thiolated HEC. No mucoadhesion was observed in case of unmodified HEC. Results were in a good agreement with rheological studies. The presence of free thiol moieties likely caused lower degree of hydrolysis by xylanase, whereas the degradation by both enzymes cellulase and xylanase was more hampered when 6-MNA was introduced as ligand for thiol group's protection. Findings in cell viability revealed that all three conjugates were non-toxic. S-protection of thiolated hydroxyethyl cellulose improved mucoadhesive properties and provided pronounced stability towards enzymatic attack, that makes this excipient superior for non-invasive drug administration over thiolated and unmodified forms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparative distribution of sulphur, thiols and disulphides in the porcine stratum corneum.

PubMed

Meyer, W; Zschemisch, N H; Lehmann, H; Busche, R; Kunz, U

2005-01-01

Biochemical, histochemical and cytochemical analyses were used to determine the sulphur contents and the thiol and disulphide distribution in the stratum corneum (SC) of the wild boar (WB), a large domestic pig breed (DP) and the Goettingen miniature pig (GMP). The sulphur contents (% DW) were different in the three animal types (WB: 1.70-1.38 body, 0.54 ear; DP: 0.84-0.53 body, 0.50 ear; GMP: 2.28-2.51 body, 2.66 ear). The results of the histochemical analysis of SH- and -S-S- groups were clear, and densitometrical extinctions were highest in most body regions of the GMP for thiols and disulphides, followed by the DP for thiols, and the WB for disulphides. Absolute SC thickness was highest in the body of the GMP (62-80 mum), and generally lowest in the ear (20-38 mum) of all animal types. Relative SC thickness was the same for all animals in the body (40-66%), but lower in the ear (30%). Only -S-S- concentrations were correlated with SC thickness, and primarily in the GMP. Cytochemical analysis showed that high sulphur concentrations were obvious particularly in the CCE of corneal cells in the DP, as compared to the cytoplasm. Intracellular sulphur distribution was homogenous in the WB, and in the GMP, although in the latter at a higher concentration level. The results indicate breed-related effects on keratinisation in porcine corneal cells. Only the SC of the outer side of the ear of DP females is recommended as a model for humans.

Hydrophobic thiol-ene surfaces fabricated via plasma activation and photo polymerization

NASA Astrophysics Data System (ADS)

Champathet, P.; Ervithayasuporn, V.; Osotchan, T.; Dangtip, S.

2017-09-01

Alumina, such as glazed alumina for electrical insulator, operated in an open field subjects to a very harsh condition; resulting in lifetime shortening. Coating hydrophobic layer on alumina surface can help prolonging its lifetime. In this study, 25 ×25 mm alumina sheets were used as substrates. The hydrophobic composite polymers were prepared from (3-mercaptopropyl)trimethoxysilane(MPTMS), 2,4,6,8-tetramethyl-2,4,6,8tetravinylcyclotetra siloxane(TMTVSi), pentaerythritoltetra(3-mercaptopropionate)(PETMP), 2,2-dimethoxy-2-phe nylaceto phenone(photoinitiator) and heptadecafluorodecylmethacrylate(HEFDMA) via the thiol-ene reaction. The alumina sheets were first activated by dielectric-barrier discharge plasma to improve its adhesion. All the polymers were found to optimize at the ratio of (MPTMS:TMTVSi:PETMP:HDFDMA) to 4:2:1:2 for coating on the alumina substrate. To enhance polymerization, 2,2-dimethoxy-2-phenylaceto phenome was also used as a photoinitiator A proper mixing sequence in the thiol-ene reaction results in film with excellent surface retention after prolong soaking in solvent such as acetone. FTIR shows that S-H and C=C functional groups have significantly changed after photopolymerization and thermally cured. The static contact angle increase from mere 53.0°±1.5° of the uncoated substrate to 120.0°±1.2° after coating. SEM shows the film with clear appearance of a few-micron thick. Under AFM, the coated surface roughness was about 9.3 nm with evenly distributed spikes of a few nanometer in height. The cross-cut test also confirmed the film was very smooth and none of the square of the films detached.

Dynamic thiol/disulfide homeostasis and effects of smoking on homeostasis parameters in patients with psoriasis.

PubMed

Emre, Selma; Demirseren, Duriye Deniz; Alisik, Murat; Aktas, Akin; Neselioglu, Salim; Erel, Ozcan

2017-12-01

Recently, increased reactive oxygen species (ROS), reduced antioxidant capacity, and oxidative stress have been suggested in the pathogenesis of psoriasis. The aim of this study to evaluate the thiol/disulfide homeostasis in patients with psoriasis. Ninety patients with psoriasis who did not receive any systemic treatment in the last six  months were included in the study. Seventy-six age and gender-matched healthy volunteers served as control group. Thiol/disulfide homeostasis was measured in venous blood samples obtained from patient and control groups. Native thiol and total thiol levels were significantly higher in patients than in control group. When thiol/disulfide hemostasis parameters and clinical and demographic characteristics were compared, a negative correlation was detected between native thiol and total thiol with age. The levels of total thiols had also negative correlation with PASI and duration of the disease. When we divided the patients into smokers and non-smokers, native thiol and total thiol levels were significantly higher in smokers than in controls, whereas native thiol and total thiol levels were comparable in non-smoker patients and controls. Thiol/disulfide balance shifted towards thiol in psoriasis patients and this may be responsible for increased keratinocyte proliferation in the pathogenesis of psoriasis.

Arsenic speciation for the phytoremediation by the Chinese brake fern, Pteris vittata.

PubMed

Shoji, R; Yajima, R; Yano, Y

2008-01-01

Arsenic (As) speciation for the phytoremediation by the Chinese brake fern was studied. In particular, the mechanism of how plants induce compounds containing thiol (SH) and proteins by As exposure in terms of the relationship between As and phosphate uptaken into plant cells was examined. Pteris vittata callus could efficiently reduce As(V) to As(III) by the rapid introduction of reductase and synthesize thiols leading to phytochelatins production. Furthermore, Pteris vittata could control phosphate concentration in the cells corresponding to the concentration of arsenite and arsenate. To our best knowledge, this is the first report to show the mechanisms of such high As tolerance of Pteris vittata using their callus in terms of in vitro approach for the analysis of As speciation and metabolism route.

Epidermal growth factor receptor-targeted lipid nanoparticles retain self-assembled nanostructures and provide high specificity

NASA Astrophysics Data System (ADS)

Zhai, Jiali; Scoble, Judith A.; Li, Nan; Lovrecz, George; Waddington, Lynne J.; Tran, Nhiem; Muir, Benjamin W.; Coia, Gregory; Kirby, Nigel; Drummond, Calum J.; Mulet, Xavier

2015-02-01

Next generation drug delivery utilising nanoparticles incorporates active targeting to specific sites. In this work, we combined targeting with the inherent advantages of self-assembled lipid nanoparticles containing internal nano-structures. Epidermal growth factor receptor (EGFR)-targeting, PEGylated lipid nanoparticles using phytantriol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-PEG-maleimide amphiphiles were created. The self-assembled lipid nanoparticles presented here have internal lyotropic liquid crystalline nano-structures, verified by synchrotron small angle X-ray scattering and cryo-transmission electron microscopy, that offer the potential of high drug loading and enhanced cell penetration. Anti-EGFR Fab' fragments were conjugated to the surface of nanoparticles via a maleimide-thiol reaction at a high conjugation efficiency and retained specificity following conjugation to the nanoparticles. The conjugated nanoparticles were demonstrated to have high affinity for an EGFR target in a ligand binding assay.Next generation drug delivery utilising nanoparticles incorporates active targeting to specific sites. In this work, we combined targeting with the inherent advantages of self-assembled lipid nanoparticles containing internal nano-structures. Epidermal growth factor receptor (EGFR)-targeting, PEGylated lipid nanoparticles using phytantriol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-PEG-maleimide amphiphiles were created. The self-assembled lipid nanoparticles presented here have internal lyotropic liquid crystalline nano-structures, verified by synchrotron small angle X-ray scattering and cryo-transmission electron microscopy, that offer the potential of high drug loading and enhanced cell penetration. Anti-EGFR Fab' fragments were conjugated to the surface of nanoparticles via a maleimide-thiol reaction at a high conjugation efficiency and retained specificity following conjugation to the nanoparticles. The conjugated nanoparticles were demonstrated to have high affinity for an EGFR target in a ligand binding assay. Electronic supplementary information (ESI) available: Fig. S1-S4. See DOI: 10.1039/c4nr05200e

Cellular uptake: lessons from supramolecular organic chemistry.

PubMed

Gasparini, Giulio; Bang, Eun-Kyoung; Montenegro, Javier; Matile, Stefan

2015-07-04

The objective of this Feature Article is to reflect on the importance of established and emerging principles of supramolecular organic chemistry to address one of the most persistent problems in life sciences. The main topic is dynamic covalent chemistry on cell surfaces, particularly disulfide exchange for thiol-mediated uptake. Examples of boronate and hydrazone exchange are added for contrast, comparison and completion. Of equal importance are the discussions of proximity effects in polyions and counterion hopping, and more recent highlights on ring tension and ion pair-π interactions. These lessons from supramolecular organic chemistry apply to cell-penetrating peptides, particularly the origin of "arginine magic" and the "pyrenebutyrate trick," and the currently emerging complementary "disulfide magic" with cell-penetrating poly(disulfide)s. They further extend to the voltage gating of neuronal potassium channels, gene transfection, and the delivery of siRNA. The collected examples illustrate that the input from conceptually innovative chemistry is essential to address the true challenges in biology beyond incremental progress and random screening.

Surface decoration of red blood cells with maleimidophenyl-polyethylene glycol facilitated by thiolation with iminothiolane: an approach to mask A, B, and D antigens to generate universal red blood cells.

PubMed

Nacharaju, Parimala; Boctor, Fouad N; Manjula, Belur N; Acharya, Seetharama A

2005-03-01

The surface decoration of red blood cells (RBCs) by polyethylene glycol (PEG) chains has been an approach developed to camouflage the blood group antigens from their antibodies. A PEGylation protocol, however, that can mask the antigens appropriately to inhibit the agglutination of RBCs with the respective antibodies is not available so far. A new approach for PEGylation of RBC membrane proteins has been designed with thiolation-mediated maleimide chemistry. The accessibility of the surface lysine residues of membrane proteins to bulky PEG reagents was increased by linking an extension arm carrying a thiol group. RBCs have been PEGylated by thiolation-mediated chemistry with maleimidophenyl-PEG (Mal-Phe-PEG) reagents of different chain lengths. Mal-Phe-PEG-5000 chains alone masked the most important antigens of the Rh system (C, c, E, e, and D) from their antibodies. The masking of the A and B antigens needed a combination of Mal-Phe-PEG-5000 and Mal-Phe-PEG-20000 chains to inhibit the agglutination of RBCs completely with anti-A or anti-B. Thiolation-mediated PEGylation of RBCs with Mal-Phe-PEG-5000 and Mal-Phe-PEG-20000 converts Group A Rh(D)+ and B Rh(D)+ RBCs into RBCs with serologic behavior comparable to Group O Rh(D)- RBCs that are considered as universal RBCs for transfusion.

Photoassisted photoluminescence fine-tuning of gold nanodots through free radical-mediated ligand-assembly

NASA Astrophysics Data System (ADS)

Tseng, Yu-Ting; Cherng, Rochelle; Harroun, Scott G.; Yuan, Zhiqin; Lin, Tai-Yuan; Wu, Chien-Wei; Chang, Huan-Tsung; Huang, Chih-Ching

2016-05-01

In this study, we have developed a simple photoassisted ligand assembly to fine-tune the photoluminescence (PL) of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide-capped gold nanodots (11-MUTAB-Au NDs). The 11-MUTAB-Au NDs (size: ca. 1.8 nm), obtained from the reaction of gold nanoparticles (ca. 3 nm) and 11-MUTAB, exhibited weak, near-infrared (NIR) PL at 700 nm with a quantum yield (QY) of 0.37% upon excitation at 365 nm. The PL QY of the Au NDs increased to 11.43% after reaction with 11-mercaptoundecanoic acid (11-MUA) for 30 min under ultraviolet (UV) light, which was accompanied by a PL wavelength shift to the green region (~520 nm). UV-light irradiation accelerates 11-MUA assembly on the 11-MUTABAu NDs (11-MUA/11-MUTAB-Au NDs) through a radical-mediated reaction. Furthermore, the PL wavelength of the 11-MUA/11-MUTAB-Au NDs can be switched to 640 nm via cysteamine under UV-light irradiation. We propose that the PL of the Au NDs with NIR and visible emissions was originally from the surface thiol-Au complexes and the Au core, respectively. These dramatically different optical properties of the Au NDs were due to variation in the surface ligands, as well as the densities and surface oxidant states of the surface Au atoms/ions. These effects can be controlled by assembling surface thiol ligands and accelerated by UV irradiation.In this study, we have developed a simple photoassisted ligand assembly to fine-tune the photoluminescence (PL) of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide-capped gold nanodots (11-MUTAB-Au NDs). The 11-MUTAB-Au NDs (size: ca. 1.8 nm), obtained from the reaction of gold nanoparticles (ca. 3 nm) and 11-MUTAB, exhibited weak, near-infrared (NIR) PL at 700 nm with a quantum yield (QY) of 0.37% upon excitation at 365 nm. The PL QY of the Au NDs increased to 11.43% after reaction with 11-mercaptoundecanoic acid (11-MUA) for 30 min under ultraviolet (UV) light, which was accompanied by a PL wavelength shift to the green region (~520 nm). UV-light irradiation accelerates 11-MUA assembly on the 11-MUTABAu NDs (11-MUA/11-MUTAB-Au NDs) through a radical-mediated reaction. Furthermore, the PL wavelength of the 11-MUA/11-MUTAB-Au NDs can be switched to 640 nm via cysteamine under UV-light irradiation. We propose that the PL of the Au NDs with NIR and visible emissions was originally from the surface thiol-Au complexes and the Au core, respectively. These dramatically different optical properties of the Au NDs were due to variation in the surface ligands, as well as the densities and surface oxidant states of the surface Au atoms/ions. These effects can be controlled by assembling surface thiol ligands and accelerated by UV irradiation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00795c

MURI Center for Materials Chemistry in the Space Environment

DTIC Science & Technology

2006-11-30

ionic species in relevant reaction environments, surface photochemistry expertise, synchrotron-based measurement and irradiation, synthesis of structural...and Ne+ ions with dodecanethiolate and semifluorinated dodecanethiolate self-assembled monolayers (SAM), polyhedral oligomeric silsesquioxane (POSS...POSS/Kapton models as gas phase species, and with alkane thiol self assembled monolayers on gold surfaces, and with liquid squalane. We have also

Transport of selenium across the plasma membrane of primary hepatocytes and enterocytes of rainbow trout.

PubMed

Misra, Sougat; Kwong, Raymond W M; Niyogi, Som

2012-05-01

Transport of essential solutes across biological membranes is one of the fundamental characteristics of living cells. Although selenium is an essential micronutrient, little is known about the cellular mechanisms of chemical species-specific selenium transport in fish. We report here the kinetic and pharmacological transport characteristics of selenite and its thiol (glutathione and l-cysteine) derivatives in primary cultures of hepatocytes and isolated enterocytes of rainbow trout. Findings from the current study suggest an apparent low-affinity linear transport system for selenite in both cell types. However, we recorded high-affinity Hill kinetics (K(d)=3.61±0.28 μmol l(-1)) in enterocytes exposed to selenite in the presence of glutathione. The uptake of selenite in the presence of thiols was severalfold higher than uptake of selenite alone (at equimolar concentration) in both hepatocytes and enterocytes. Cellular accumulation of selenium was found to be energy independent. Interestingly, we observed a decrease in selenite transport with increasing pH, whereas selenite uptake increased with increasing pH in the presence glutathione in both cell types. The cellular uptake of selenite demonstrated a pronounced competitive interaction with a structurally similar compound, sulfite. The uptake of selenite as well as its thiol derivatives was found to be sensitive to the anion transport blocker DIDS, irrespective of the cell type. Inorganic mercury (Hg(2+)) elicited an inhibition of selenite transport in both cell types, but augmented the transport of reduced forms of selenite in hepatocytes. Based on the substrate choice and comparable pharmacological properties, we advocate that multiple anion transport systems are probably involved in the cellular transport of selenite in fish.

The role of glutathione in DNA damage by potassium bromate in vitro.

PubMed

Parsons, J L; Chipman, J K

2000-07-01

We have investigated the role of reduced glutathione (GSH) in the genetic toxicity of the rodent renal carcinogen potassium bromate (KBrO(3)). A statistically significant increase in the concentration of 8-oxodeoxyguanosine (8-oxodG) relative to deoxyguanosine was measured following incubation of calf thymus DNA with KBrO(3) and GSH or N-acetylcysteine (NACys). This was dependent on these thiols and was associated with the loss of GSH and production of oxidized glutathione. A short-lived (<6 min) intermediate was apparent which did not react with the spin trap dimethylpyrroline N-oxide. DNA oxidation was not evident when potassium chlorate (KClO(3)) or potassium iodate (KIO(3)) were used instead of KBrO(3), though GSH depletion also occurred with KIO(3), but not with KClO(3). Other reductants and thiols in combination with KBrO(3) did not cause a significant increase in DNA oxidation. DNA strand breakage was also induced by KBrO(3) in human white blood cells (5 mM) and rat kidney epithelial cells (NRK-52E, 1.5 mM). This was associated with an apparent small depletion of thiols in NRK-52E cells at 15 min and with an elevation of 8-oxodG at a delayed time of 24 h. Depletion of intra-cellular GSH by diethylmaleate in human lymphocytes decreased the amount of strand breakage induced by KBrO(3). Extracellular GSH, however, protected against DNA strand breakage by KBrO(3), possibly due to the inability of the reactive product to enter the cell. In contrast, membrane-permeant NACys enhanced KBrO(3)-induced DNA strand breakage in these cells. DNA damage by KBrO(3) is therefore largely dependent on access to intracellular GSH.

Synthesis of novel thiol-functionalized mesoporous silica nanorods and their sorbent properties on heavy metals

NASA Astrophysics Data System (ADS)

Chen, Xi; Cai, Qiang; Sun, Lin-Hao; Zhang, Wei; Jiang, Xing-Yu

2012-09-01

Novel thiol-functionalized mesoporous silica nanorods (MSNRs) were synthesized through a base co-condensation method, in which two organoalkoxysilanes, tetraethoxylsilane (TEOS) and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT), were used as silica precursors simultaneously. TESPT was firstly used for both morphology control and inner surface functionalization of mesoporous silica hybrid materials. The microstructures as well as porous character of the MSNRs were characterized by means of SEM, XRD, TEM and N2 sorption measurements. Infrared spectrum analysis and heavy metal ions (Ag+ and Cd2+) adsorption measurements were carried out to confirm the functionalized framework of MSNRs.

Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross-Linking Proteins.

PubMed

Wallisch, Melanie; Sulmann, Stefan; Koch, Karl-Wilhelm; Christoffers, Jens

2017-05-11

Diaminoterephthalates are fluorescent dyes and define scaffolds, which can be orthogonally functionalized at their two carboxylate residues with functional residues bearing task specific reactive groups. The synthesis of monofunctionalized dyes with thiol groups for surface binding, an azide for click chemistry, and a biotinoylated congener for streptavidin binding is reported. Two bifunctionalized dyes were prepared: One with an azide for click chemistry and a biotin for streptavidin binding, the other with a maleimide for reaction with thiol and a cyclooctyne moiety for ligation with copper-free click chemistry. In general, the compounds are red to orange, fluorescent materials with an absorption at about 450 nm and an emission at 560 nm with quantum yields between 2-41 %. Of particular interest is the maleimide-functionalized compound, which shows low fluorescence quantum yield (2 %) by itself. After addition of a thiol, the fluorescence is "turned on"; quantum yield 41 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water-soluble CdTe nanocrystals under high pressure

NASA Astrophysics Data System (ADS)

Lin, Yan-Cheng

2015-02-01

The application of static high pressure provides a method for precisely controlling and investigating many fundamental and unique properties of semiconductor nanocrystals (NCs). This study systematically investigates the high-pressure photoluminescence (PL) and time-resolved carrier dynamics of thiol-capped CdTe NCs of different sizes, at different concentrations, and in various stress environments. The zincblende-to-rocksalt phase transition in thiol-capped CdTe NCs is observed at a pressure far in excess of the bulk phase transition pressure. Additionally, the process of transformation depends strongly on NC size, and the phase transition pressure increases with NC size. These peculiar phenomena are attributed to the distinctive bonding of thiols to the NC surface. In a nonhydrostatic environment, considerable flattening of the PL energy of CdTe NCs powder is observed above 3.0 GPa. Furthermore, asymmetric and double-peak PL emissions are obtained from a concentrated solution of CdTe NCs under hydrostatic pressure, implying the feasibility of pressure-induced interparticle coupling.

Investigation of the H2S poisoning process for sensing composite material based on carbon nanotubes and metal oxides

PubMed Central

Duan, Yichen; Pirolli, Laurent; Teplyakov, Andrew V.

2016-01-01

The poisoning of H2S sensing material based on the mixture of acid-treated carbon nanotubes, CuO and SnO2 was investigated by exposing the material to high doses of H2S (1% in volume) and following the changes spectroscopically. The presence of metal sulfides (CuS and SnS2), sulfates and thiols was confirmed on the surface of this material as the result of H2S poisoning. Further study revealed that leaving this material in air for extended period of time led to reoxidation of metal sulfides back to metal oxides. The formation of thiols and sulfates directly on carbon nanotubes is not reversible under these conditions; however, the extent of the overall surface reaction in this case is substantially lower than that for the composite material. PMID:27812240

Investigation of the H2S poisoning process for sensing composite material based on carbon nanotubes and metal oxides.

PubMed

Duan, Yichen; Pirolli, Laurent; Teplyakov, Andrew V

2016-11-01

The poisoning of H 2 S sensing material based on the mixture of acid-treated carbon nanotubes, CuO and SnO 2 was investigated by exposing the material to high doses of H 2 S (1% in volume) and following the changes spectroscopically. The presence of metal sulfides (CuS and SnS 2 ), sulfates and thiols was confirmed on the surface of this material as the result of H 2 S poisoning. Further study revealed that leaving this material in air for extended period of time led to reoxidation of metal sulfides back to metal oxides. The formation of thiols and sulfates directly on carbon nanotubes is not reversible under these conditions; however, the extent of the overall surface reaction in this case is substantially lower than that for the composite material.

S-protected thiolated chitosan for oral delivery of hydrophilic macromolecules: evaluation of permeation enhancing and efflux pump inhibitory properties.

PubMed

Dünnhaupt, Sarah; Barthelmes, Jan; Rahmat, Deni; Leithner, Katharina; Thurner, Clemens C; Friedl, Heike; Bernkop-Schnürch, Andreas

2012-05-07

The objective of this study was the investigation of permeation enhancing and P-glycoprotein (P-gp) inhibition effects of a novel thiolated chitosan, the so-named S-protected thiolated chitosan. Mediated by a carbodiimide, increasing amounts of thioglycolic acid (TGA) were covalently bound to chitosan (CS) in the first step of modification. In the second step, these thiol groups of thiolated chitosan were protected by disulfide bond formation with the thiolated aromatic residue 6-mercaptonicotinamide (6-MNA). Mucoadhesive properties of all conjugates were evaluated in vitro on porcine intestinal mucosa based on tensile strength investigations. Permeation enhancing effects were evaluated ex vivo using rat intestinal mucosa and in vitro via Caco-2 cells using the hydrophilic macromolecule FD(4) as the model drug. Caco-2 cells were further used to show P-gp inhibition effects by using Rho-123 as P-gp substrate. Apparent permeability coefficients (P(app)) were calculated and compared to values obtained from each buffer control. Three different thiolated chitosans were generated in the first step of modification, which displayed increasing amounts of covalently attached free thiol groups on the polymer backbone. In the second modification step, more than 50% of these free thiol groups were covalently linked with 6-MNA. Within 3 h of permeation studies on excised rat intestine, P(app) values of all S-protected chitosans were at least 1.3-fold higher compared to those of corresponding thiomers and more than twice as high as that of unmodified chitosan. Additional permeation studies on Caco-2 cells confirmed these results. Because of the chemical modification and higher amount of reactive thiol groups, all S-protected thiolated chitosans exhibit at least 1.4-fold pronounced P-gp inhibition effects in contrast to their corresponding thiomers. These features approve S-protected thiolated chitosan as a promising excipient for various drug delivery systems providing improved permeation enhancing and efflux inhibition effects.

Impaired Thiol-Disulfide Balance in Acute Brucellosis.

PubMed

Kolgelier, Servet; Ergin, Merve; Demir, Lutfi Saltuk; Inkaya, Ahmet Cagkan; Aktug Demir, Nazlim; Alisik, Murat; Erel, Ozcan

2017-05-24

The objective of this study was to examine a novel profile: thiol-disulfide homeostasis in acute brucellosis. The study included 90 patients with acute brucellosis, and 27 healthy controls. Thiol-disulfide profile tests were analyzed by a recently developed method, and ceruloplasmin levels were determined. Native thiol levels were 256.72 ± 48.20 μmol/L in the acute brucellosis group and 461.13 ± 45.37 μmol/L in the healthy group, and total thiol levels were 298.58 ± 51.78 μmol/L in the acute brucellosis group and 504.83 ± 51.05 μmol/L in the healthy group (p < 0.001, for both). The disulfide/native thiol ratios and disulfide/total thiol ratios were significantly higher, and native thiol/total thiol ratios were significantly lower in patients with acute brucellosis than in the healthy controls (p < 0.001, for all ratios). There were either positive or negative relationships between ceruloplasmin levels and thiol-disulfide parameters. The thiol-disulfide homeostasis was impaired in acute brucellosis. The strong associations between thiol-disulfide parameters and a positive acute-phase reactant reflected the disruption of the balance between the antioxidant and oxidant systems. Since thiol groups act as anti-inflammatory mediators, the alteration in the thiol-disulfide homeostasis may be involved in brucellosis.

Synthesis of soybean oil-based thiol oligomers.

PubMed

Wu, Jennifer F; Fernando, Shashi; Weerasinghe, Dimuthu; Chen, Zhigang; Webster, Dean C

2011-08-22

Industrial grade soybean oil (SBO) and thiols were reacted to generate thiol-functionalized oligomers via a thermal, free radical initiated thiol-ene reaction between the SBO double bond moieties and the thiol functional groups. The effect of the reaction conditions, including thiol concentration, catalyst loading level, reaction time, and atmosphere, on the molecular weight and the conversion to the resultant soy-thiols were examined in a combinatorial high-throughput fashion using parallel synthesis, combinatorial FTIR, and rapid gel permeation chromatography (GPC). High thiol functionality and concentration, high thermal free radical catalyst concentration, long reaction time, and the use of a nitrogen reaction atmosphere were found to favor fast consumption of the SBO, and produced high molecular weight products. The thiol conversion during the reaction was inversely affected by a high thiol concentration, but was favored by a long reaction time and an air reaction atmosphere. These experimental observations were explained by the initial low affinity of the SBO and thiol, and the improved affinity between the generated soy-thiol oligomers and unreacted SBO during the reaction. The synthesized soy-thiol oligomers can be used for renewable thiol-ene UV curable materials and high molecular solids and thiourethane thermal cure materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The thiol compounds glutathione and homoglutathione differentially affect cell development in alfalfa (Medicago sativa L.).

PubMed

Pasternak, Taras; Asard, Han; Potters, Geert; Jansen, Marcel A K

2014-01-01

Glutathione (GSH) is an important scavenger of Reactive Oxygen Species (ROS), precursor of metal chelating phytochelatins, xenobiotic defence compound and regulator of cell proliferation. Homoglutathione (hGSH) is a GSH homologue that is present in several taxa in the family of Fabaceae. It is thought that hGSH performs many of the stress-defence roles typically ascribed to GSH, yet little is known about the potential involvement of hGSH in controlling cell proliferation. Here we show that hGSH/GSH ratios vary across organs and cells and that these changes in hGSH/GSH ratio occur during dedifferentiation and/or cell cycle activation events. The use of a GSH/hGSH biosynthesis inhibitor resulted in impaired cytokinesis in isolated protoplasts, showing the critical importance of these thiol-compounds for cell division. However, exposure of isolated protoplasts to exogenous GSH accelerated cytokinesis, while exogenous hGSH was found to inhibit the same process. We conclude that GSH and hGSH have distinct functional roles in cell cycle regulation in Medicago sativa L. GSH is associated with meristemic cells, and promotes cell cycle activation and induction of somatic embryogenesis, while hGSH is associated with differentiated cells and embryo proliferation. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Self-assembling siloxane bilayer directly on SiO2 surface of micro-cantilevers for long-term highly repeatable sensing to trace explosives.

PubMed

Chen, Ying; Xu, Pengcheng; Li, Xinxin

2010-07-02

This paper presents a novel sensing layer modification technique for static micro-cantilever sensors that detect trace explosives by measuring specific adsorption-induced surface stress. For the first time, a method of directly modifying a siloxane sensing bilayer on an SiO(2) surface is proposed to replace the conventional self-assembled monolayers (SAMs) of thiols on Au to avoid the trouble from long-term unstable Au-S bonds. For modifying the long-term reliable sensing bilayer on the piezoresistor-integrated micro-cantilevers, a siloxane-head bottom layer is self-assembled directly on the SiO(2) cantilever surface, which is followed by grafting another explosive-sensing-group functionalized molecule layer on top of the siloxane layer. The siloxane-modified sensor has experimentally exhibited a highly resoluble response to 0.1 ppb TNT vapor. More importantly, the repeated detection results after 140 days show no obvious attenuation in sensing signal. Also observed experimentally, the specific adsorption of the siloxane sensing bilayer to TNT molecules causes a tensile surface stress on the cantilever. Herein the measured tensile surface stress is in contrast to the compressive surface stress normally measured from conventional cantilever sensors where the sensitive thiol-SAMs are modified on an Au surface. The reason for this newly observed phenomenon is discussed and preliminarily analyzed.

A hybrid biocatalyst consisting of silver nanoparticle and naphthalenethiol self-assembled monolayer prepared for anchoring glucose oxidase and its use for an enzymatic biofuel cell

NASA Astrophysics Data System (ADS)

Christwardana, Marcelinus; Kim, Do-Heyoung; Chung, Yongjin; Kwon, Yongchai

2018-01-01

A novel hybrid biocatalyst is synthesized by the enzyme composite consisting of silver nanoparticle (AgNP), naphthalene-thiol based couplers (Naph-SH) and glucose oxidase (GOx), which is then bonded with the supporter consisting of polyethyleneimine (PEI) and carbon nanotube (CNT) (CNT/PEI/AgNPs/Naph-SH/GOx) to facilitate glucose oxidation reaction (GOR). Here, the AgNPs play a role in obstructing denaturation of the GOx molecules from the supporter because of Ag-thiol bond, while the PEIs have the AgNPs keep their states without getting ionized by hydrogen peroxide produced during anodic reaction. The Naph-SHs also prevent ionization of the AgNP by forming self-assembled monolayer on their surface. Such roles of each component enable the catalyst to form (i) hydrophobic interaction between the GOx molecules and supporter and (ii) π-conjugated electron pathway between the GOx molecules and AgNP, promoting electron transfer. Catalytic nature of the catalyst is characterized by measuring catalytic activity and performance of enzymatic biofuel cell (EBC) using the catalyst. Regarding the catalytic activity, the catalyst leads to high electron transfer rate constant (9.6 ± 0.4 s-1), low Michaelis-Menten constant (0.51 ± 0.04 mM), and low charge transfer resistance (7.3 Ω cm2) and high amount of immobilized GOx (54.6%), while regarding the EBC performance, high maximum power density (1.46 ± 0.07 mW cm-2) with superior long-term stability result are observed.

Designing an ultra-sensitive aptasensor based on an AgNPs/thiol-GQD nanocomposite for TNT detection at femtomolar levels using the electrochemical oxidation of Rutin as a redox probe.

PubMed

Shahdost-Fard, Faezeh; Roushani, Mahmoud

2017-01-15

In this paper, for the first time a highly sensitive and low-cost electrochemical aptasensor was fabricated based on a silver nanoparticles/thiol functionalized graphene quantum dot (AgNPs/thiol-GQD) nanocomposite for the measurement of 2,4,6-Trinitrotoluen (TNT) as a nitroaromatic explosive. For the first time Rutin (RU) as a biological molecule with inherent properties was used as the redox probe in the development of the TNT aptasensor was used. The system was based on a TNT-binding aptamer which is covalently attached onto the surface of a glassy carbon electrode (GCE) modified with the nanocomposite for the formation of a sensing layer and improving the performance of the aptasensor. Using the proposed nanocomposite provides a specific platform with increased surface area which is capable of loading more Aptamer (Ap) molecules as a receptor element of TNT on the electrode surface. So, TNT molecules is in an upward position to be measured and the obtained results indicate that the aptasensor exhibits two wide linear ranges and an unprecedented LOD compared with previously reported analytical methods for TNT detection. Applicability of the developed aptasensor to easily detect TNT in real samples was evaluated. It seems that the proposed strategy can be expanded to other nanoparticles and is expected to have promising implications in the design of electrochemical sensors or biosensors for the detection of various targets. Copyright © 2016 Elsevier B.V. All rights reserved.

Gold nanoparticles on titanium and interaction with prototype protein.

PubMed

Padmos, J Daniel; Duchesne, Paul; Dunbar, Michael; Zhang, Peng

2010-10-01

Modifying titanium (Ti) implant surfaces with functional proteins can strengthen the interface between prosthesis and bone. A prototype system was developed using gold nanoparticles (AuNPs) to immobilize proteins onto Ti. An electroless (galvanic displacement) deposition method was first used to form AuNPs of controlled size and coverage on commercial Ti foil (giving Ti-AuNPs). Parameters were then modified to create two groups of discs (n = 26) with different average AuNP diameters. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the morphology and surface structure of Ti-AuNPs. To study the interaction of Ti-AuNPs with proteins, Ti discs (n = 8) modified with plain AuNPs and discs (n = 8) modified with thiol (HS--R--COOH)-functionalized AuNPs were treated with lysozyme solution. The amount and activity of the lysozyme on the discs were examined with Micro-BCA and enzymatic assays. Lysozyme was immobilized onto the discs, and the assays showed that the discs with thiol-functionalized AuNPs, discs with bare AuNPs, and Ti controls had average lysozyme adsorptions of 23 x 10(4), 2.3 x 10(4), and 5.7 x 10(4) microg/m2, respectively. The activity assays showed that 21.5, 18.4, and 12.5% of the adsorbed lysozyme was active on the discs with thiol-functionalized AuNPs, discs with bare AuNPs, and Ti controls, respectively. This technique holds promise for binding functional biomolecules to surgical implants, hence possibly creating implant surfaces that react to their local environment. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

The Intracellular Redox Stress Caused by Hexavalent Chromium is Selective for Proteins that Have Key Roles in Cell Survival and Thiol Redox Control

PubMed Central

Myers, Judith M.; Antholine, William E.; Myers, Charles R.

2011-01-01

Hexavalent chromium [Cr(VI)] compounds (e.g. chromates) are strong oxidants that readily enter cells where they are reduced to reactive Cr intermediates that can directly oxidize some cell components and can promote the generation of reactive oxygen and nitrogen species. Inhalation is a major route of exposure which directly exposes the bronchial epithelium. Previous studies with non-cancerous human bronchial epithelial cells (BEAS-2B) demonstrated that Cr(VI) treatment results in the irreversible inhibition of thioredoxin reductase (TrxR) and the oxidation of thioredoxins (Trx) and peroxiredoxins (Prx). The mitochondrial Trx/Prx system is somewhat more sensitive to Cr(VI) than the cytosolic Trx/Prx system, and other redox-sensitive mitochondrial functions are subsequently affected including electron transport complexes I and II. Studies reported here show that Cr(VI) does not cause indiscriminant thiol oxidation, and that the Trx/Prx system is among the most sensitive of cellular protein thiols. Trx/Prx oxidation is not unique to BEAS-2B cells, as it was also observed in primary human bronchial epithelial cells. Increasing the intracellular levels of ascorbate, an endogenous Cr(VI) reductant, did not alter the effects on TrxR, Trx, or Prx. The peroxynitrite scavenger MnTBAP did not protect TrxR, Trx, Prx, or the electron transport chain from the effects of Cr(VI), implying that peroxynitrite is not required for these effects. Nitration of tyrosine residues of TrxR was not observed following Cr(VI) treatment, further ruling out peroxynitrite as a significant contributor to the irreversible inhibition of TrxR. Cr(VI) treatments that disrupt the TrxR/Trx/Prx system did not cause detectable mitochondrial DNA damage. Overall, the redox stress that results from Cr(VI) exposure shows selectivity for key proteins which are known to be important for redox signaling, antioxidant defense, and cell survival. PMID:21237240

Surface-Engineered Multifunctional Eu:Gd2O3 Nanoplates for Targeted and pH-Responsive Drug Delivery and Imaging Applications.

PubMed

Saha, Arindam; Mohanta, Subas Chandra; Deka, Kashmiri; Deb, Pritam; Devi, Parukuttyamma Sujatha

2017-02-01

In this paper, we report the synthesis of surface-engineered multifunctional Eu:Gd 2 O 3 triangular nanoplates with small size and uniform shape via a high-temperature solvothermal technique. Surface engineering has been performed by a one-step polyacrylate coating, followed by controlled conjugation chemistry. This creates the desired number of surface functional groups that can be used to attach folic acid as a targeting ligand on the nanoparticle surface. To specifically deliver the drug molecules in the nucleus, the folate density on the nanoparticle surface has been kept low. We have also modified the drug molecules with terminal double bond and ester linkage for the easy conjugation of nanoparticles. The nanoparticle surface was further modified with free thiols to specifically attach the modified drug molecules with a pH-responsive feature. High drug loading has been encountered for both hydrophilic drug daunorubicin (∼69% loading) and hydrophobic drug curcumin (∼75% loading) with excellent pH-responsive drug release. These nanoparticles have also been used as imaging probes in fluorescence imaging. Some preliminary experiments to evaluate their application in magnetic resonance imaging have also been explored. A detailed fluorescence imaging study has confirmed the efficient delivery of drugs to the nuclei of cancer cells with a high cytotoxic effect. Synthesized surface-engineered nanomaterials having small hydrodynamic size, excellent colloidal stability, and high drug-loading capacity, along with targeted and pH-responsive delivery of dual drugs to the cancer cells, will be potential nanobiomaterials for various biomedical applications.

Ultrasensitive electrochemical aptasensor based on sandwich architecture for selective label-free detection of colorectal cancer (CT26) cells.

PubMed

Hashkavayi, Ayemeh Bagheri; Raoof, Jahan Bakhsh; Ojani, Reza; Kavoosian, Saeid

2017-06-15

Colorectal cancer is one of the most common cancers in the world and has no effective treatment. Therefore, development of new methods for early diagnosis is instantly required. Biological recognition probes such as synthetic receptor and aptamer is one of the candidate recognition layers to detect important biomolecules. In this work, an electrochemical aptasensor was developed by fabricating an aptamer-cell-aptamer sandwich architecture on an SBA-15-3-aminopropyltriethoxysilane (SBA-15-pr-NH 2 ) and Au nanoparticles (AuNPs) modified graphite screen printed electrode (GSPE) surface for the selective, label-free detection of CT26 cancer cells. Based on the incubation of the thiolated aptamer with CT26 cells, the electron-transfer resistance of Fe (CN) 6 3-/4- redox couple increased considerably on the aptasensor surface. The results obtained from cyclic voltammetry and electrochemical impedance spectroscopy studies showed that the fabricated aptasensor can specifically identify CT26 cells in the concentration ranges of 10-1.0×10 5 cells/mL and 1.0×10 5 -6.0×10 6 cells/mL, respectively, with a detection limit of 2cells/mL. Applying the thiol terminated aptamer (5TR1) as a recognition layer led to a sensor with high affinity for CT26 cancer cells, compared to control cancer cells of AGS cells, VERO Cells, PC3 cells and SKOV-3 cells. Therefore a simple, rapid, label free, inexpensive, excellent, sensitive and selective electrochemical aptasensor based on sandwich architecture was developed for detection of CT26 Cells. Copyright © 2016 Elsevier B.V. All rights reserved.

[Physico-chemical features of dinitrosyl iron complexes with natural thiol-containing ligands underlying biological activities of these complexes].

PubMed

Vanin, A F; Borodulin, R R; Kubrina, L N; Mikoian, V D; Burbaev, D Sh

2013-01-01

Current notions and new experimental data of the authors on physico-chemical features of dinitrosyl iron complexes with natural thiol-containing ligands (glutathione or cysteine), underlying the ability of the complexes to act as NO molecule and nitrosonium ion donors, are considered. This ability determines various biological activities of dinitrosyl iron complexes--inducing long-lasting vasodilation and thereby long-lasting hypotension in human and animals, inhibiting pellet aggregation, increasing red blood cell elasticity, thereby stimulating microcirculation, and reducing necrotic zone in animals with myocardial infarction. Moreover, dinitrosyl iron complexes are capable of accelerating skin wound healing, improving the function of penile cavernous tissue, blocking apoptosis development in cell cultures. When decomposed dinitrosyl iron complexes can exert cytotoxic effect that can be used for curing infectious and carcinogenic pathologies.

Detection of Cysteine Redox States in Mitochondrial Proteins in Intact Mammalian Cells.

PubMed

Habich, Markus; Riemer, Jan

2017-01-01

Import, folding, and activity regulation of mitochondrial proteins are important for mitochondrial function. Cysteine residues play crucial roles in these processes as their thiol groups can undergo (reversible) oxidation reactions. For example, during import of many intermembrane space (IMS) proteins, cysteine oxidation drives protein folding and translocation over the outer membrane. Mature mitochondrial proteins can undergo changes in the redox state of specific cysteine residues, for example, as part of their enzymatic reaction cycle or as adaptations to changes of the local redox environment which might influence their activity. Here we describe methods to study changes in cysteine residue redox states in intact cells. These approaches allow to monitor oxidation-driven protein import as well as changes of cysteine redox states in mature proteins during oxidative stress or during the reaction cycle of thiol-dependent enzymes like oxidoreductases.

Long-wavelength TCF-based fluorescence probes for the detection and intracellular imaging of biological thiols.

PubMed

Sedgwick, Adam C; Gardiner, Jordan E; Kim, Gyoungmi; Yevglevskis, Maksims; Lloyd, Matthew D; Jenkins, A Toby A; Bull, Steven D; Yoon, Juyoung; James, Tony D

2018-05-08

Two 'turn on' TCF-based fluorescence probes were developed for the detection of biological thiols (TCF-GSH and TCFCl-GSH). TCF-GSH was shown to have a high sensitivity towards glutathione (GSH) with a 0.28 μM limit of detection. Unfortunately, at higher GSH concentrations the fluorescence intensity of TCF-GSH decreased and toxicity was observed for TCF-GSH in live cells. However, TCFCl-GSH was shown to be able to detect GSH at biologically relevant concentrations with a 0.45 μM limit of detection. No toxicity was found for TCFCl-GSH and a clear 'turn on' with good photostability was observed for the exogenous addition of GSH, Cys and HCys. Furthermore, TCFCl-GSH was used to evaluate the effects of drug treatment on the levels of GSH in live cells.

Protective effect and mechanism of glutaredoxin 1 on coronary arteries endothelial cells damage induced by high glucose.

PubMed

Li, Shuyan; Sun, Yan; Qi, Xiaodan; Shi, Yan; Gao, Han; Wu, Qi; Liu, Xiucai; Yu, Haitao; Zhang, Chunjing

2014-01-01

In recent years, diabetes and its associated complications have become a major public health concern. The cardiovascular risk increases significantly in diabetes patients. It is a complex disease characterized by multiple metabolic derangements and is known to impair cardiac function by disrupting the balance between pro-oxidants and antioxidants at the cellular level. The subsequent generation of reactive oxygen species (ROS) and accompanying oxidative stress are hallmarks of the molecular mechanisms responsible for cardiovascular disease. Protein thiols act as redox-sensitive switches and are believed to be a key element in maintaining the cellular redox balance. The redox state of protein thiols is regulated by oxidative stress and redox signaling and is important to cellular functions. The potential of the thiol-disulfide oxidoreductase enzymes (thioredoxin and glutaredoxin systems) in defense against oxidative stress has been noted previously. Increasing evidence demonstrates that glutaredoxin 1 (Grx1), a cytosolic enzyme responsible for the catalysis of protein deglutathionylation, plays distinct roles in inflammation and apoptosis by inducing changes in the cellular redox system. This study investigates whether and how Grx1 protects coronary artery vascular endothelial cells against high glucose (HG) induced damage. Results indicate that the activation of eNOS/NO system is regulated by Grx 1 and coupled with inhibition of JNK and NF-κB signaling pathway which could alleviate the oxidative stress and apoptosis damage in coronary arteries endothelial cells induced by HG.

Inactivation of thiol-dependent enzymes by hypothiocyanous acid: role of sulfenyl thiocyanate and sulfenic acid intermediates

PubMed Central

Barrett, Tessa J.; Pattison, David I.; Leonard, Stephen E.; Carroll, Kate S.; Davies, Michael J.; Hawkins, Clare L.

2012-01-01

Myeloperoxidase (MPO) forms reactive oxidants including hypochlorous and hypothiocyanous acids (HOCl and HOSCN) under inflammatory conditions. HOCl causes extensive tissue damage and plays a role in the progression of many inflammatory-based diseases. Although HOSCN is a major MPO oxidant, particularly in smokers, who have elevated plasma thiocyanate, the role of this oxidant in disease is poorly characterized. HOSCN induces cellular damage by targeting thiols. However, the specific targets and mechanisms involved in this process are not well defined. We show that exposure of macrophages to HOSCN results in the inactivation of intracellular enzymes, including creatine kinase (CK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In each case, the active-site thiol residue is particularly sensitive to oxidation, with evidence for reversible inactivation and the formation of sulfenyl thiocyanate and sulfenic acid intermediates, on treatment with HOSCN (less than fivefold molar excess). Experiments with DAz-2, a cell-permeable chemical trap for sulfenic acids, demonstrate that these intermediates are formed on many cellular proteins, including GAPDH and CK, in macrophages exposed to HOSCN. This is the first direct evidence for the formation of protein sulfenic acids in HOSCN-treated cells and highlights the potential of this oxidant to perturb redox signaling processes. PMID:22248862

A nitric oxide/cysteine interaction mediates the activation of soluble guanylate cyclase

PubMed Central

Fernhoff, Nathaniel B.; Derbyshire, Emily R.; Marletta, Michael A.

2009-01-01

Nitric oxide (NO) regulates a number of essential physiological processes by activating soluble guanylate cyclase (sGC) to produce the second messenger cGMP. The mechanism of NO sensing was previously thought to result exclusively from NO binding to the sGC heme; however, recent studies indicate that heme-bound NO only partially activates sGC and additional NO is involved in the mechanism of maximal NO activation. Furthermore, thiol oxidation of sGC cysteines results in the loss of enzyme activity. Herein the role of cysteines in NO-stimulated sGC activity investigated. We find that the thiol modifying reagent methyl methanethiosulfonate specifically inhibits NO activation of sGC by blocking a non-heme site, which defines a role for sGC cysteine(s) in mediating NO binding. The nature of the NO/cysteine interaction was probed by examining the effects of redox active reagents on NO-stimulated activity. These results show that NO binding to, and dissociation from, the critical cysteine(s) does not involve a change in the thiol redox state. Evidence is provided for non-heme NO in the physiological activation of sGC in context of a primary cell culture of human umbilical vein endothelial cells. These findings have relevance to diseases involving the NO/cGMP signaling pathway. PMID:20007374

Novel Anti-Biofouling Soft Contact Lens: l-Cysteine Conjugated Amphiphilic Conetworks via RAFT and Thiol-Ene Click Chemistry.

PubMed

Zhang, Chengfeng; Liu, Ziyuan; Wang, Haiye; Feng, Xiaofeng; He, Chunju

2017-07-01

A unique l-cysteine conjugated antifouling amphiphilic conetwork (APCN) is synthesized through end-crosslinking of well-defined triblock copolymers poly(allyl methacrylate)-b-poly(ethylene glycol)-b-poly(allyl methacrylate) via a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene "click" chemistry. The synthesized poly(ethylene glycol) macro-RAFT agent initiates the polymerization of allyl methacrylate in a controlled manner. The vinyl pendant groups of the precursor partially conjugate with l-cysteine and the rest fully crosslink with mercaptopropyl-containing siloxane via thiol-ene click chemistry under UV irradiation into APCNs, which show distinguished properties, that is, excellent biocompatibility, more than 39.6% water content, 101 barrers oxygen permeability, optimized mechanical properties, and more than 93% visible light transmittance. What's more, the resultant APCNs exhibit eminent resistance to protein adsorption, where the bovine serum albumin and lysozyme adsorption are decreased to 12 and 21 µg cm -2 , respectively. The outstanding properties of APCNs depend on the RAFT controlled method, which precisely designs the hydrophilic/hydrophobic segments and eventually greatly improves the crosslinking efficiency and homogeneity. Meantime, the l-cysteine monolayer can effectively reduce the surface hydrophobicity and prevent protein adsorption, which exhibits the viability for antifouling surface over and under ophthalmic devices, suggesting a promising soft contact lens. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical copatterning strategies using azlactone-based block copolymers

DOE PAGES

Masigol, Mohammadali; Barua, Niloy; Retterer, Scott T.; ...

2017-09-01

Interfaces can be modified with azlactone-functional polymers in order to manipulate the chemical surface reactivity. Azlactone groups are highly reactive toward amine, thiol, and alcohol nucleophiles, providing a versatile coupling chemistry for secondary surface modification. Azlactone-based surface polymers have been explored in numerous applications, including chemical and biological capture, sensing, and cell culture. These applications often require that the polymer is copatterned within a chemically or biologically inert background; however, common fabrication methods degrade azlactone groups during processing steps or result in polymer films with poorly controlled thicknesses. Here, the authors develop fabrication strategies using parylene lift-off and interface-directed assemblymore » methods to generate microscale patterns of azlactone-based block copolymer in chemically or biologically inert backgrounds. The functionality of azlactone groups was preserved during fabrication, and patterned films appeared as uniform, 80–120nm brushlike films. The authors also develop a patterning approach that uses a novel microcontact stamping method to generate cross-linked, three-dimensional structures of azlactone-based polymers with controllable, microscale thicknesses. The authors identify the benefits of each approach and expect these polymers and patterning strategies to provide a versatile toolbox for developing synthetic interfaces with tuned chemical and physical features for sensing, cell culture, or material capture applications.« less

Chemical copatterning strategies using azlactone-based block copolymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masigol, Mohammadali; Barua, Niloy; Retterer, Scott T.

Interfaces can be modified with azlactone-functional polymers in order to manipulate the chemical surface reactivity. Azlactone groups are highly reactive toward amine, thiol, and alcohol nucleophiles, providing a versatile coupling chemistry for secondary surface modification. Azlactone-based surface polymers have been explored in numerous applications, including chemical and biological capture, sensing, and cell culture. These applications often require that the polymer is copatterned within a chemically or biologically inert background; however, common fabrication methods degrade azlactone groups during processing steps or result in polymer films with poorly controlled thicknesses. Here, the authors develop fabrication strategies using parylene lift-off and interface-directed assemblymore » methods to generate microscale patterns of azlactone-based block copolymer in chemically or biologically inert backgrounds. The functionality of azlactone groups was preserved during fabrication, and patterned films appeared as uniform, 80–120nm brushlike films. The authors also develop a patterning approach that uses a novel microcontact stamping method to generate cross-linked, three-dimensional structures of azlactone-based polymers with controllable, microscale thicknesses. The authors identify the benefits of each approach and expect these polymers and patterning strategies to provide a versatile toolbox for developing synthetic interfaces with tuned chemical and physical features for sensing, cell culture, or material capture applications.« less

Immobilization of DNA onto poly(dimethylsiloxane) surfaces and application to a microelectrochemical enzyme-amplified DNA hybridization assay.

PubMed

Liu, Daojun; Perdue, Robbyn K; Sun, Li; Crooks, Richard M

2004-07-06

This paper describes immobilization of DNA onto the interior walls of poly(dimethylsiloxane) (PDMS) microsystems and its application to an enzyme-amplified electrochemical DNA assay. DNA immobilization was carried out by silanization of the PDMS surface with 3-mercaptopropyltrimethoxysilane to yield a thiol-terminated surface. 5'-acrylamide-modified DNA reacts with the pendant thiol groups to yield DNA-modified PDMS. Surface-immobilized DNA oligos serve as capture probes for target DNA. Biotin-labeled target DNA hybridizes to the PDMS-immobilized capture DNA, and subsequent introduction of alkaline phosphatase (AP) conjugated to streptavidin results in attachment of the enzyme to hybridized DNA. Electrochemical detection of DNA hybridization benefits from enzyme amplification. Specifically, AP converts electroinactive p-aminophenyl phosphate to electroactive p-aminophenol, which is detected using an indium tin oxide interdigitated array (IDA) electrode. The IDA electrode eliminates the need for a reference electrode and provides a steady-state current that is related to the concentration of hybridized DNA. At present, the limit of detection of the DNA target is 1 nM in a volume of 20 nL, which corresponds to 20 attomoles of DNA.

Photonics and microarray technology

NASA Astrophysics Data System (ADS)

Skovsen, E.; Duroux, M.; Neves-Petersen, M. T.; Duroux, L.; Petersen, S. B.

2007-05-01

Photonic induced immobilization of biosensor molecules is a novel technology that results in spatially oriented and spatially localized covalent coupling of a large variety of biomolecules onto thiol reactive surfaces, e.g. thiolated glass, quartz, gold or silicon. The reaction mechanism behind the reported new technology involves light-induced breakage of disulphide bridges in proteins upon UV illumination of nearby aromatic amino acids resulting in the formation of reactive molecules that will form covalent bonds with thiol reactive surfaces. This new technology has the potential of replacing present micro dispensing arraying technologies, where the size of the individual sensor spots are limited by the size of the dispensed droplets. Using light-induced immobilization the spatial resolution is defined by the area of the sensor surface that is illuminated by UV light and not by the physical size of the dispensed droplets of sensor molecules. This new technology allows for dense packing of different biomolecules on a surface, allowing the creation of multi-potent functionalized materials, such as biosensors with micrometer sized individual sensor spots. Thus, we have developed the necessary technology for preparing large protein arrays of enzymes and fragments of antibodies, with micrometer resolution, without the need for liquid micro dispensing.

Synthesis of Stable Citrate-Capped Silver Nanoprisms.

PubMed

Haber, Jason; Sokolov, Konstantin

2017-10-10

Citrate-stabilized silver nanoprisms (AgNPrs) can be easily functionalized using well-developed thiol based surface chemistry that is an important requirement for biosensor applications utilizing localized surface plasmon resonance (LSPR) and surface-enhanced Raman Scattering (SERS). Unfortunately, currently available protocols for synthesis of citrate-coated AgNPrs do not produce stable nanoparticles thus limiting their usefulness in biosensing applications. Here we address this problem by carrying out a systematic study of citrate-stabilized, peroxide-based synthesis of AgNPrs to optimize reaction conditions for production of stable and reproducible nanoprisms. Our analysis showed that concentration of secondary reducing agent, l-ascorbic acid, is critical to AgNPr stability. Furthermore, we demonstrated that optimization of other synthesis conditions such as stabilizer concentration, rate of silver nitrate addition, and seed dilution result in highly stable nanoprisms with narrow absorbance peaks ranging from 450 nm into near-IR. In addition, the optimized reaction conditions can be used to produce AgNPrs in a one-pot synthesis instead of a previously described two-step reaction. The resulting nanoprisms can readily interact with thiols for easy surface functionalization. These studies provide an optimized set of parameters for precise control of citrate stabilized AgNPr synthesis for biomedical applications.

Investigation of molybdenum-crosslinker interfaces for affinity based electrochemical biosensing applications

NASA Astrophysics Data System (ADS)

Kamakoti, Vikramshankar; Shanmugam, Nandhinee Radha; Tanak, Ambalika Sanjeev; Jagannath, Badrinath; Prasad, Shalini

2018-04-01

Molybdenum (Mo) has been investigated for implementation as an electrode material for affinity based biosensing towards devloping flexibe electronic biosensors. Treatment of the native oxide of molybdenum was investigated through two surface treatment strategies namely thiol and carbodiimide crosslinking methods. The binding interaction between cross-linker molecules and Mo electrode surface has been characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and optical microscopy. The efficacy of treatment of Mo with its native oxide using carbodiimide cross linking methodology was established. The carbodiimide cross-linking chemistry was found to possess better surface coverage and binding affinity with Molybdenum electrode surface when compared to thiol cross-linking chemistry.Electrochemical characterization of Mo electrode using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltametry (CV) techniques was performed to evaluate the effect of ionic properties of solution buffer on the Mo electrode's performance. Affinity based biosensing of C-Reactive Protein (CRP) has been demonstrated on a flexible nanoporous polymeric substrate with detection threshold of 100 pg/ml in synthetic urine buffer medium. The biosensor has been evaluated to be developed as a dipstick based point of care device for detection of biomarkers in urine.

Effect of thiol pendant conjugates on plasmid DNA binding, release, and stability of polymeric delivery vectors.

PubMed

Bacalocostantis, Irene; Mane, Viraj P; Kang, Michael S; Goodley, Addison S; Muro, Silvia; Kofinas, Peter

2012-05-14

Polymers have attracted much attention as potential gene delivery vectors due to their chemical and structural versatility. However, several challenges associated with polymeric carriers, including low transfection efficiencies, insufficient cargo release, and high cytotoxicity levels have prevented clinical implementation. Strong electrostatic interactions between polymeric carriers and DNA cargo can prohibit complete cargo release within the cell. As a result, cargo DNA never reaches the cell's nucleus where gene expression takes place. In addition, highly charged cationic polymers have been correlated with high cytotoxicity levels, making them unsuitable carriers in vivo. Using poly(allylamine) (PAA) as a model, we investigated how pH-sensitive disulfide cross-linked polymer networks can improve the delivery potential of cationic polymer carriers. To accomplish this, we conjugated thiol-terminated pendant chains onto the primary amines of PAA using 2-iminothiolane, developing three new polymer vectors with 5, 13, or 20% thiol modification. Unmodified PAA and thiol-conjugated polymers were tested for their ability to bind and release plasmid DNA, their capacity to protect genetic cargo from enzymatic degradation, and their potential for endolysosomal escape. Our results demonstrate that polymer-plasmid complexes (polyplexes) formed by the 13% thiolated polymer demonstrate the greatest delivery potential. At high N/P ratios, all thiolated polymers (but not unmodified counterparts) were able to resist decomplexation in the presence of heparin, a negatively charged polysaccharide used to mimic in vivo polyplex-protein interactions. Further, all thiolated polymers exhibited higher buffering capacities than unmodified PAA and, therefore, have a greater potential for endolysosomal escape. However, 5 and 20% thiolated polymers exhibited poor DNA binding-release kinetics, making them unsuitable carriers for gene delivery. The 13% thiolated polymers, on the other hand, displayed high DNA binding efficiency and pH-sensitive release.

Real-time Kinetics of High-mobility Group Box 1 (HMGB1) Oxidation in Extracellular Fluids Studied by in Situ Protein NMR Spectroscopy*

PubMed Central

Zandarashvili, Levani; Sahu, Debashish; Lee, Kwanbok; Lee, Yong Sun; Singh, Pomila; Rajarathnam, Krishna; Iwahara, Junji

2013-01-01

Some extracellular proteins are initially secreted in reduced forms via a non-canonical pathway bypassing the endoplasmic reticulum and become oxidized in the extracellular space. One such protein is HMGB1 (high-mobility group box 1). Extracellular HMGB1 has different redox states that play distinct roles in inflammation. Using a unique NMR-based approach, we have investigated the kinetics of HMGB1 oxidation and the half-lives of all-thiol and disulfide HMGB1 species in serum, saliva, and cell culture medium. In this approach, salt-free lyophilized 15N-labeled all-thiol HMGB1 was dissolved in actual extracellular fluids, and the oxidation and clearance kinetics were monitored in situ by recording a series of heteronuclear 1H-15N correlation spectra. We found that the half-life depends significantly on the extracellular environment. For example, the half-life of all-thiol HMGB1 ranged from ∼17 min (in human serum and saliva) to 3 h (in prostate cancer cell culture medium). Furthermore, the binding of ligands (glycyrrhizin and heparin) to HMGB1 significantly modulated the oxidation kinetics. Thus, the balance between the roles of all-thiol and disulfide HMGB1 proteins depends significantly on the extracellular environment and can also be artificially modulated by ligands. This is important because extracellular HMGB1 has been suggested as a therapeutic target for inflammatory diseases and cancer. Our work demonstrates that the in situ protein NMR approach is powerful for investigating the behavior of proteins in actual extracellular fluids containing an enormous number of different molecules. PMID:23447529

Proteomic Identification and Quantification of S-glutathionylation in Mouse Macrophages Using Resin-Assisted Enrichment and Isobaric Labeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Dian; Gaffrey, Matthew J.; Guo, Jia

2014-02-11

Protein S-glutathionylation (SSG) is an important regulatory posttranslational modification of protein cysteine (Cys) thiol redox switches, yet the role of specific cysteine residues as targets of modification is poorly understood. We report a novel quantitative mass spectrometry (MS)-based proteomic method for site-specific identification and quantification of S-glutathionylation across different conditions. Briefly, this approach consists of initial blocking of free thiols by alkylation, selective reduction of glutathionylated thiols and enrichment using thiol affinity resins, followed by on-resin tryptic digestion and isobaric labeling with iTRAQ (isobaric tags for relative and absolute quantitation) for MS-based identification and quantification. The overall approach was validatedmore » by application to RAW 264.7 mouse macrophages treated with different doses of diamide to induce glutathionylation. A total of 1071 Cys-sites from 690 proteins were identified in response to diamide treatment, with ~90% of the sites displaying >2-fold increases in SSG-modification compared to controls.. This approach was extended to identify potential SSG modified Cys-sites in response to H2O2, an endogenous oxidant produced by activated macrophages and many pathophysiological stimuli. The results revealed 364 Cys-sites from 265 proteins that were sensitive to S-glutathionylation in response to H2O2 treatment. These proteins covered a range of molecular types and molecular functions with free radical scavenging, and cell death and survival included as the most significantly enriched functional categories. Overall the results demonstrate that our approach is effective for site-specific identification and quantification of S-glutathionylated proteins. The analytical strategy also provides a unique approach to determining the major pathways and cell processes most susceptible to glutathionylation at a proteome-wide scale.« less

Core-shell polymer nanoparticles for prevention of GSH drug detoxification and cisplatin delivery to breast cancer cells

NASA Astrophysics Data System (ADS)

Surnar, Bapurao; Sharma, Kavita; Jayakannan, Manickam

2015-10-01

Platinum drug delivery against the detoxification of cytoplasmic thiols is urgently required for achieving efficacy in breast cancer treatment that is over expressed by glutathione (GSH, thiol-oligopeptide). GSH-resistant polymer-cisplatin core-shell nanoparticles were custom designed based on biodegradable carboxylic functional polycaprolactone (PCL)-block-poly(ethylene glycol) diblock copolymers. The core of the nanoparticle was fixed as 100 carboxylic units and the shell part was varied using various molecular weight poly(ethylene glycol) monomethyl ethers (MW of PEGs = 100-5000 g mol-1) as initiator in the ring-opening polymerization. The complexation of cisplatin aquo species with the diblocks produced core-shell nanoparticles of 75 nm core with precise size control the particles up to 190 nm. The core-shell nanoparticles were found to be stable in saline solution and PBS and they exhibited enhanced stability with increase in the PEG shell thickness at the periphery. The hydrophobic PCL layer on the periphery of the cisplatin core behaved as a protecting layer against the cytoplasmic thiol residues (GSH and cysteine) and exhibited <5% of drug detoxification. In vitro drug-release studies revealed that the core-shell nanoparticles were ruptured upon exposure to lysosomal enzymes like esterase at the intracellular compartments. Cytotoxicity studies were performed both in normal wild-type mouse embryonic fibroblast cells (Wt-MEFs), and breast cancer (MCF-7) and cervical cancer (HeLa) cell lines. Free cisplatin and polymer drug core-shell nanoparticles showed similar cytotoxicity effects in the HeLa cells. In MCF-7 cells, the free cisplatin drug exhibited 50% cell death whereas complete cell death (100%) was accomplished by the polymer-cisplatin core-shell nanoparticles. Confocal microscopic images confirmed that the core-shell nanoparticles were taken up by the MCF-7 and HeLa cells and they were accumulated both at the cytoplasm as well at peri-nuclear environments. The present investigation lays a new foundation for the polymer-based core-shell nanoparticles approach for overcoming detoxification in platinum drugs for the treatment of GSH over-expressed breast cancer cells.Platinum drug delivery against the detoxification of cytoplasmic thiols is urgently required for achieving efficacy in breast cancer treatment that is over expressed by glutathione (GSH, thiol-oligopeptide). GSH-resistant polymer-cisplatin core-shell nanoparticles were custom designed based on biodegradable carboxylic functional polycaprolactone (PCL)-block-poly(ethylene glycol) diblock copolymers. The core of the nanoparticle was fixed as 100 carboxylic units and the shell part was varied using various molecular weight poly(ethylene glycol) monomethyl ethers (MW of PEGs = 100-5000 g mol-1) as initiator in the ring-opening polymerization. The complexation of cisplatin aquo species with the diblocks produced core-shell nanoparticles of 75 nm core with precise size control the particles up to 190 nm. The core-shell nanoparticles were found to be stable in saline solution and PBS and they exhibited enhanced stability with increase in the PEG shell thickness at the periphery. The hydrophobic PCL layer on the periphery of the cisplatin core behaved as a protecting layer against the cytoplasmic thiol residues (GSH and cysteine) and exhibited <5% of drug detoxification. In vitro drug-release studies revealed that the core-shell nanoparticles were ruptured upon exposure to lysosomal enzymes like esterase at the intracellular compartments. Cytotoxicity studies were performed both in normal wild-type mouse embryonic fibroblast cells (Wt-MEFs), and breast cancer (MCF-7) and cervical cancer (HeLa) cell lines. Free cisplatin and polymer drug core-shell nanoparticles showed similar cytotoxicity effects in the HeLa cells. In MCF-7 cells, the free cisplatin drug exhibited 50% cell death whereas complete cell death (100%) was accomplished by the polymer-cisplatin core-shell nanoparticles. Confocal microscopic images confirmed that the core-shell nanoparticles were taken up by the MCF-7 and HeLa cells and they were accumulated both at the cytoplasm as well at peri-nuclear environments. The present investigation lays a new foundation for the polymer-based core-shell nanoparticles approach for overcoming detoxification in platinum drugs for the treatment of GSH over-expressed breast cancer cells. Electronic supplementary information (ESI) available: TGA profile and DSC thermogram of all polymers, DLS data, AFM image, 1H-NMR, 13C-NMR, and MALDI spectra of all polymers and monomers. See DOI: 10.1039/c5nr04963f

Electrochemistry, surface plasmon resonance, and quartz crystal microbalance: an associative study on cytochrome c adsorption on pyridine tail-group monolayers on gold.

PubMed

Paulo, Tércio de F; de Sousa, Ticyano P; de Abreu, Dieric S; Felício, Nathalie H; Bernhardt, Paul V; Lopes, Luiz G de F; Sousa, Eduardo H S; Diógenes, Izaura C N

2013-07-25

Quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and electrochemistry techniques were used to study the electron-transfer (ET) reaction of cytochrome c (Cyt c) on gold surfaces modified with thionicotinamide, thioisonicotinamide, 4-mercaptopyridine, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 5-phenyl-1,3,4-oxadiazole-2-thiol, 4,4'-bipyridine, and 4,4'-dithiopyridine. The electrochemical results showed that the ET process is complex, being chiefly diffusional with steps depending on the orientation of the pyridine or phenyl tail group of the modifiers. The correlation between the electrochemical results and those acquired by SPR and QCM indicated the presence of an adlayer of Cyt c adsorbed on the thiolate SAMs. This adlayer, although being not electroactive, is essential to assess the ET reaction of Cyt c in solution. The results presented in this work are consistent with the statement (Feng, Z. Q.; Imabayashi, S.; Kakiuchi, T.; Niki, K. J. Electroanal. Chem. 1995, 394, 149-154) that the ET reaction of Cyt c can be explained in terms of the through-bond tunneling mechanism.

Vitamin K3 suppressed inflammatory and immune responses in a redox-dependent manner.

PubMed

Checker, Rahul; Sharma, Deepak; Sandur, Santosh K; Khan, Nazir M; Patwardhan, Raghavendra S; Kohli, Vineet; Sainis, Krishna B

2011-08-01

Recent investigations suggest that cellular redox status may play a key role in the regulation of several immune functions. Treatment of lymphocytes with vitamin K3 (menadione) resulted in a significant decrease in cellular GSH/GSSG ratio and concomitant increase in the ROS levels. It also suppressed Concanavalin A (Con A)-induced proliferation and cytokine production in lymphocytes and CD4 + T cells in vitro. Immunosuppressive effects of menadione were abrogated only by thiol containing antioxidants. Mass spectrometric analysis showed that menadione directly interacted with thiol antioxidant GSH. Menadione completely suppressed Con A-induced activation of ERK, JNK and NF-κB in lymphocytes. It also significantly decreased the homeostasis driven proliferation of syngeneic CD4 + T cells. Further, menadione significantly delayed graft-vs-host disease morbidity and mortality in mice. Menadione suppressed phytohemagglutinin-induced cytokine production in human peripheral blood mononuclear cells. These results reveal that cellular redox perturbation by menadione is responsible for significant suppression of lymphocyte responses.

Allicin disrupts the cell's electrochemical potential and induces apoptosis in yeast.

PubMed

Gruhlke, Martin C H; Portz, Daniela; Stitz, Michael; Anwar, Awais; Schneider, Thomas; Jacob, Claus; Schlaich, Nikolaus L; Slusarenko, Alan J

2010-12-15

The volatile substance allicin gives crushed garlic (Allium sativum) its characteristic odor and is a pro-oxidant that undergoes thiol-disulfide exchange reactions with -SH groups in proteins and glutathione. The antimicrobial activity of allicin is suspected to be due to the oxidative inactivation of essential thiol-containing enzymes. We investigated the hypothesis that at threshold inhibitory levels allicin can shunt yeast cells into apoptosis by altering their overall redox status. Yeast cells were treated either with chemically synthesized, pure allicin or with allicin in garlic juice. Allicin-dependent cell oxidation was demonstrated with a redox-sensitive GFP construct and the shift in cellular electrochemical potential (E(hc)) from less than -215 to -181mV was calculated using the Nernst equation after the glutathione/glutathione disulfide couple (2GSH/GSSG) in the cell was quantified. Caspase activation occurred after allicin treatment, and yeast expressing a human antiapoptotic Bcl-XL construct was rendered more resistant to allicin. Also, a yeast apoptosis-inducing factor deletion mutant was more resistant to allicin than wild-type cells. We conclude that allicin in garlic juice can activate apoptosis in yeast cells through its oxidizing properties and that this presents an alternative cell-killing mechanism to the previously proposed specific oxidative inactivation of essential enzymes. Copyright © 2010 Elsevier Inc. All rights reserved.

Diselenolane-mediated cellular uptake† †Electronic supplementary information (ESI) available: Detailed procedures and results for all reported experiments. See DOI: 10.1039/c7sc05151d

PubMed Central

Chuard, Nicolas; Poblador-Bahamonde, Amalia I.; Zong, Lili; Bartolami, Eline; Hildebrandt, Jana; Weigand, Wolfgang; Sakai, Naomi

2018-01-01

The emerging power of thiol-mediated uptake with strained disulfides called for a move from sulfur to selenium. We report that according to results with fluorescent model substrates, cellular uptake with 1,2-diselenolanes exceeds uptake with 1,2-dithiolanes and epidithiodiketopiperazines with regard to efficiency as well as intracellular localization. The diselenide analog of lipoic acid performs best. This 1,2-diselenolane delivers fluorophores efficiently to the cytosol of HeLa Kyoto cells, without detectable endosomal capture as with 1,2-dithiolanes or dominant escape into the nucleus as with epidithiodiketopiperazines. Diselenolane-mediated cytosolic delivery is non-toxic (MTT assay), sensitive to temperature but insensitive to inhibitors of endocytosis (chlorpromazine, methyl-β-cyclodextrin, wortmannin, cytochalasin B) and conventional thiol-mediated uptake (Ellman's reagent), and to serum. Selenophilicity, the extreme CSeSeC dihedral angle of 0° and the high but different acidity of primary and secondary selenols might all contribute to uptake. Thiol-exchange affinity chromatography is introduced as operational mimic of thiol-mediated uptake that provides, in combination with rate enhancement of DTT oxidation, direct experimental evidence for existence and nature of the involved selenosulfides. PMID:29675232

S-Nitrosation of monocarboxylate transporter 1: Inhibition of pyruvate-fueled respiration and proliferation of breast cancer cells

PubMed Central

Diers, Anne R.; Broniowska, Katarzyna A.; Chang, Ching-Fang; Hill, R. Blake; Hogg, Neil

2014-01-01

Summary Energy substrates metabolized through mitochondria (e.g., pyruvate, glutamine) are required for biosynthesis of macromolecules in proliferating cells. Since several mitochondrial proteins are known to be targets of S-nitrosation, we determined whether bioenergetics are modulated by S-nitrosation and defined the subsequent effects on proliferation. The nitrosating agent S-nitroso-L-cysteine (L-CysNO) was used to initiate intracellular S-nitrosation, and treatment decreased mitochondrial function and inhibited proliferation of MCF7 mammary adenocarcinoma cells. Surprisingly, the D isomer of CysNO (D-CysNO) which is not transported into cells also caused mitochondrial dysfunction and limited proliferation. Both L- and D-CysNO also inhibited cellular pyruvate uptake and caused S-nitrosation of thiol groups on monocarboxylate transporter 1, a proton-linked pyruvate transporter. These data demonstrate the importance of mitochondrial metabolism in proliferative responses in breast cancer and highlight a novel role for inhibition of metabolic substrate uptake through S-nitrosation of exofacial protein thiols in cellular responses to nitrosative stress. PMID:24486553

Surface-Enhanced Raman and Surface-Enhanced Hyper-Raman Scattering of Thiol-Functionalized Carotene

PubMed Central

2016-01-01

A thiol-modified carotene, 7′-apo-7′-(4-mercaptomethylphenyl)-β-carotene, was used to obtain nonresonant surface-enhanced Raman scattering (SERS) spectra of carotene at an excitation wavelength of 1064 nm, which were compared with resonant SERS spectra at an excitation wavelength of 532 nm. These spectra and surface-enhanced hyper-Raman scattering (SEHRS) spectra of the functionalized carotene were compared with the spectra of nonmodified β-carotene. Using SERS, normal Raman, and SEHRS spectra, all obtained for the resonant case, the interaction of the carotene molecules with silver nanoparticles, as well as the influence of the resonance enhancement and the SERS enhancement on the spectra, were investigated. The interaction with the silver surface occurs for both functionalized and nonfunctionalized β-carotene, but only the stronger functionalization-induced interaction enables the acquisition of nonresonant SERS spectra of β-carotene at low concentrations. The resonant SEHRS and SERS spectra are very similar. Nevertheless, the SEHRS spectra contain additional bands of infrared-active modes of carotene. Increased contributions from bands that experience low resonance enhancement point to a strong interaction between silver nanoparticles and electronic levels of the molecules, thereby giving rise to a decrease in the resonance enhancement in SERS and SEHRS. PMID:28077983

Charge Retention by Monodisperse Gold Clusters on Surfaces Prepared Using Soft Landing of Mass Selected Ions

NASA Astrophysics Data System (ADS)

Johnson, Grant; Priest, Thomas; Laskin, Julia

2012-02-01

Monodisperse gold clusters have been prepared on surfaces in different charge states through soft landing of mass-selected ions. Gold clusters were synthesized in methanol solution by reduction of a gold precursor with a weak reducing agent in the presence of a diphosphine capping ligand. Electrospray ionization was used to introduce the clusters into the gas-phase and mass-selection was employed to isolate a single ionic cluster species which was delivered to surfaces at well controlled kinetic energies. Using in-situ time of flight secondary ion mass spectrometry (SIMS) it is demonstrated that the cluster retains its 3+ charge state when soft landed onto the surface of a fluorinated self assembled monolayer on gold. In contrast, when deposited onto carboxylic acid terminated and conventional alkyl thiol surfaces on gold the clusters exhibit larger relative abundances of the 2+ and 1+ charge states, respectively. The kinetics of charge reduction on the surface have been investigated using in-situ Fourier Transform Ion Cyclotron Resonance SIMS. It is shown that an extremely slow interfacial charge reduction occurs on the fluorinated monolayer surface while an almost instantaneous neutralization takes place on the surface of the alkyl thiol monolayer. Our results demonstrate that the size and charge state of small gold clusters on surfaces, both of which exert a dramatic influence on their chemical and physical properties, may be tuned through soft landing of mass-selected ions onto selected substrates.

Advanced functionalization of polyhydroxyalkanoate via the UV-initiated thiol-ene click reaction.

PubMed

Tajima, Kenji; Iwamoto, Kosuke; Satoh, Yasuharu; Sakai, Ryosuke; Satoh, Toshifumi; Dairi, Tohru

2016-05-01

Polyhydroxyalkanoates (PHAs) incorporating vinyl-bearing 3-hydroxyalkanoates were prepared in 8.5-12.9 g L(-1) yield. The molar ratios (0-16 mol%) of the vinyl-bearing 3-hydroxyalkanoate derivatives were controlled by the continuous feeding of undecylenate at various concentrations. Subsequently, the PHAs were functionalized by UV-initiated thiol-ene click reaction and chemical modification. (1)H NMR spectra suggested that 3-mercaptopropionic acid and 2-aminoethanethiol were successfully introduced into the vinyl-bearing PHA. Subsequently, chemical modification using fluorescein or a fibronectin active fragment (GRGDS) was attempted. The former yielded a PHA derivative capable of emitting fluorescence under UV irradiation, which was useful for determining the miscibility of PHA in a composite film comprising poly-ʟ-lactic acid (PLLA) and PHA. In the latter case, PHA bearing GRGDS peptides exhibited cell adhesiveness, suggesting that its biocompatibility was improved upon peptide introduction. Taken together, the UV-initiated thiol-ene click reaction was demonstrated to be useful in PHA modification.

ortho- and meta-substituted aromatic thiols are efficient redox buffers that increase the folding rate of a disulfide-containing protein.

PubMed

Gough, Jonathan D; Barrett, Elvis J; Silva, Yenia; Lees, Watson J

2006-08-20

Thiol based redox buffers are used to enhance the folding rates of disulfide-containing proteins in vitro. Traditionally, small molecule aliphatic thiols such as glutathione are employed. Recently, we have demonstrated that aromatic thiols can further enhance protein-folding rates. In the presence of para-substituted aromatic thiols the folding rate of a disulfide-containing protein was increased by 4-23 times over that measured for glutathione. However, several important practical issues remain to be addressed. Aromatic thiols have never been tested in the presence of denaturants such as guanidine hydrochloride. Only two of the para-substituted aromatic thiols previously examined are commercially available. To expand the number of aromatic thiols for protein folding, several commercially available meta- and ortho-substituted aromatic thiols were studied. Furthermore, an ortho-substituted aromatic thiol, easily obtained from inexpensive starting materials, was investigated. Folding rates of scrambled ribonuclease A at pH 6.0, 7.0 and 7.7, with ortho- and meta-substituted aromatic thiols, were up to 10 times greater than those with glutathione. In the presence of the common denaturant guanidine hydrochloride (0.5M) aromatic thiols provided 100% yield of active protein while maintaining equivalent folding rates.

Fast and Selective Modification of Thiol Proteins/Peptides by N-(Phenylseleno)phthalimide

NASA Astrophysics Data System (ADS)

Wang, Zhengfang; Zhang, Yun; Zhang, Hao; Harrington, Peter B.; Chen, Hao

2012-03-01

We previously reported that selenamide reagents such as ebselen and N-(phenylseleno)phthalimide (NPSP) can be used to selectively derivatize thiols for mass spectrometric analysis, and the introduced selenium tags are useful as they could survive or removed with collision-induced dissociation (CID). Described herein is the further study of the reactivity of various protein/peptide thiols toward NPSP and its application to derivatize thiol peptides in protein digests. With a modified protocol (i.e., dissolving NPSP in acetonitrile instead of aqueous solvent), we found that quantitative conversion of thiols can be obtained in seconds, using NPSP in a slight excess amount (NPSP:thiol of 1.1-2:1). Further investigation shows that the thiol reactivity toward NPSP reflects its chemical environment and accessibility in proteins/peptides. For instance, adjacent basic amino acid residues increase the thiol reactivity, probably because they could stabilize the thiolate form to facilitate the nucleophilic attack of thiol on NPSP. In the case of creatine phosphokinase, the native protein predominately has one thiol reacted with NPSP while all of four thiol groups of the denatured protein can be derivatized, in accordance with the corresponding protein conformation. In addition, thiol peptides in protein/peptide enzymatic digests can be quickly and effectively tagged by NPSP following tri- n-butylphosphine (TBP) reduction. Notably, all three thiols of the peptide QCCASVCSL in the insulin peptic digest can be modified simultaneously by NPSP. These results suggest a novel and selective method for protecting thiols in the bottom-up approach for protein structure analysis.

[The sources of inorganic sulfur in the process of cluster protein Fnr[4Fe-4S]2+ reconstruction in Escherichia coli cells cultivated with NO-donating agents].

PubMed

Vasil'eva, S V; Strel'tsova, D A; Vlaskina, A V; Mikoian, V D; Vanin, A F

2012-01-01

Dinitrosyl iron complexes (DNICs) with thiol ligands--binuclear and mononuclear--inhibited aidB gene expression in E. coli cells. This process is due to the nitrosylation of the active center in iron-sulfur protein Fnr [4Fe-4S]2+ by low-molecular DNICs. The next step is transformation of the above DNICs into the DNICs with the thiol groups in the apo-form of Fnr protein. These nitrosylated proteins are characterized by the EPR signal with g perpendicular = 2.04 and g parallel 1 = 2,014. An addition of sulfur containing L-Cys or N-A-L-Cys as well as Na2S to the cells lead to the increasing in the aidB gene expression simultaneously with an appearance of the EPR signal with g perpendicular = 2.04 and g parallel = 2.02 as the characteristics of the DNICs with persulfide (R-S-S-) ligands. We suppose that the recovery of the aidB gene activity was due to the accumulation of inorganic sulfur in the cells and reconstruction of the active center in Fnr[4Fe-4S]2+. It appears that the above process is the function of L-cysteine-desulfurase protein which repaired the active center of Fnr[4Fe-4S]2+ protein using the sulfur from L-Cys or N-A-L-Cys after its deacetylation. On the other side the ions of inorganic sulfur being reacted with SH-groups led to the transformation of DNIC with thiol ligands into the persulfides. Na2S was the most potent activator of the aidB gene expression in our experiments.

The Chemical Basis of Thiol Addition to Nitro-conjugated Linoleic Acid, a Protective Cell-signaling Lipid*♦

PubMed Central

Turell, Lucía; Vitturi, Darío A.; Coitiño, E. Laura; Lebrato, Lourdes; Möller, Matías N.; Sagasti, Camila; Salvatore, Sonia R.; Woodcock, Steven R.; Alvarez, Beatriz; Schopfer, Francisco J.

2017-01-01

Nitroalkene fatty acids are formed in vivo and exert protective and anti-inflammatory effects via reversible Michael addition to thiol-containing proteins in key signaling pathways. Nitro-conjugated linoleic acid (NO2-CLA) is preferentially formed, constitutes the most abundant nitrated fatty acid in humans, and contains two carbons that could potentially react with thiols, modulating signaling actions and levels. In this work, we examined the reactions of NO2-CLA with low molecular weight thiols (glutathione, cysteine, homocysteine, cysteinylglycine, and β-mercaptoethanol) and human serum albumin. Reactions followed reversible biphasic kinetics, consistent with the presence of two electrophilic centers in NO2-CLA located on the β- and δ-carbons with respect to the nitro group. The differential reactivity was confirmed by computational modeling of the electronic structure. The rates (kon and koff) and equilibrium constants for both reactions were determined for different thiols. LC-UV-Visible and LC-MS analyses showed that the fast reaction corresponds to β-adduct formation (the kinetic product), while the slow reaction corresponds to the formation of the δ-adduct (the thermodynamic product). The pH dependence of the rate constants, the correlation between intrinsic reactivity and thiol pKa, and the absence of deuterium solvent kinetic isotope effects suggested stepwise mechanisms with thiolate attack on NO2-CLA as rate-controlling step. Computational modeling supported the mechanism and revealed additional features of the transition states, anionic intermediates, and final neutral products. Importantly, the detection of cysteine-δ-adducts in human urine provided evidence for the biological relevance of this reaction. Finally, human serum albumin was found to bind NO2-CLA both non-covalently and to form covalent adducts at Cys-34, suggesting potential modes for systemic distribution. These results provide new insights into the chemical basis of NO2-CLA signaling actions. PMID:27923813

Homo- and heteroleptic bismuth(III/V) thiolates from N-heterocyclic thiones: synthesis, structure and anti-microbial activity.

PubMed

Luqman, Ahmad; Blair, Victoria L; Brammananth, Rajini; Crellin, Paul K; Coppel, Ross L; Andrews, Philip C

2014-10-27

Homo- and heteroleptic bismuth thiolato complexes have been synthesised and characterised from biologically relevant tetrazole-, imidazole-, thiadiazole- and thiazole-based heterocyclic thiones (thiols): 1-methyl-1H-tetrazole-5-thiol (1-MMTZ(H)); 4-methyl-4H-1,2,4-triazole-3-thiol (4-MTT(H)); 1-methyl-1H-imidazole-2-thiol (2-MMI(H)); 5-methyl-1,3,4-thiadiazole-2-thiol (5-MMTD(H)); 1,3,4-thiadiazole-2-dithiol (2,5-DMTD(H)2 ); and 4-(4-bromophenyl)thiazole-2-thiol (4-BrMTD(H)). Reaction of BiPh3 with 1-MMTZ(H) produced the rare Bi(V) thiolato complex [BiPh(1-MMTZ)4 ], which undergoes reduction in DMSO to give [BiPh(1-MMTZ)2 {(1-MMTZ(H)}2 ]. Reactions with PhBiCl2 or BiPh3 generally produced monophenylbismuth thiolates, [BiPh(SR)2 ]. The crystal structures of [BiPh(1-MMTZ)2 {1-MMTZ(H)}2 ], [BiPh(5-MMTD)2 ], [BiPh{2,5-DMTD(H)}2 (Me2 CO)] and [Bi(4-BrMTD)3 ] were obtained. Evaluation of the bactericidal properties against M. smegmatis, S. aureus, MRSA, VRE, E. faecalis and E. coli showed complexes containing the anionic ligands 1- MMTZ, 4-MTT and 4-BrMTD to be most effective. The dithiolato dithione complexes [BiPh(4-MTT)2 {4-MTT(H)}2 ] and [BiPh(1-MMTZ)2 {1-MMTZ(H)}2 ] were most effective against all the bacteria: MICs 0.34 μM for [BiPh(4-MTT)2 {4-MTT(H)}2 ] against VRE, and 1.33 μM for [BiPh(1-MMTZ)2 {1-MMTZ(H)}2 ] against M. smegmatis and S. aureus. Tris-thiolato Bi(III) complexes were least effective overall. All complexes showed little or no toxicity towards mammalian COS-7 cells at 20 μg mL(-1) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thiosemicarbazone p-Substituted Acetophenone Derivatives Promote the Loss of Mitochondrial Δψ, GSH Depletion, and Death in K562 Cells

PubMed Central

Pessoto, Felipe S.; Yokomizo, Cesar H.; Prieto, Tatiana; Fernandes, Cleverton S.; Silva, Alan P.; Kaiser, Carlos R.; Basso, Ernani A.; Nantes, Iseli L.

2015-01-01

A series of thiosemicarbazone (TSC) p-substituted acetophenone derivatives were synthesized and chemically characterized. The p-substituents appended to the phenyl group of the TSC structures were hydrogen, fluor, chlorine, methyl, and nitro, producing compounds named TSC-H, TSC-F, TSC-Cl, TSC-Me, and TSC-NO2, respectively. The TSC compounds were evaluated for their capacity to induce mitochondrial permeability, to deplete mitochondrial thiol content, and to promote cell death in the K562 cell lineage using flow cytometry and fluorescence microscopy. TSC-H, TSC-F, and TSC-Cl exhibited a bell-shaped dose-response curve for the induction of apoptosis in K562 cells due to the change from apoptosis to necrosis as the principal mechanism of cell death at the highest tested doses. TSC-Me and TSC-NO2 exhibited a typical dose-response profile, with a half maximal effective concentration of approximately 10 µM for cell death. Cell death was also evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed lower toxicity of these compounds for peripheral blood mononuclear cells than for K562 cells. The possible mechanisms leading to cell death are discussed based on the observed effects of the new TSC compounds on the cellular thiol content and on mitochondrial bioenergetics. PMID:26075034

P2X(7) is a scavenger receptor for apoptotic cells in the absence of its ligand, extracellular ATP.

PubMed

Gu, Ben J; Saunders, Bernadette M; Petrou, Steven; Wiley, James S

2011-09-01

Phagocytosis of apoptotic cells is essential during development and tissue remodeling. Our previous study has shown that the P2X(7) receptor regulates phagocytosis of nonopsonized particles and bacteria. In this study, we demonstrate that P2X(7) also mediates phagocytosis of apoptotic lymphocytes and neuronal cells by human monocyte-derived macrophages under serum-free conditions. ATP inhibited this process to a similar extent as observed with cytochalasin D. P2X(7)-transfected HEK-293 cells acquired the ability to phagocytose apoptotic lymphocytes. Injection of apoptotic thymocytes into the peritoneal cavity of wild-type mice resulted in their phagocytosis by macrophages, but injection of ATP prior to thymocytes markedly decreased this uptake. In contrast, ATP failed to inhibit phagocytosis of apoptotic thymocytes in vivo by P2X(7)-deficient peritoneal macrophages. The surface expression of P2X(7) on phagocytes increased significantly during phagocytosis of either beads or apoptotic cells. A peptide screen library containing 24 biotin-conjugated peptides mimicking the extracellular domain of P2X(7) was used to evaluate the binding profile to beads, bacteria, and apoptotic cells. One peptide showed binding to all particles and cell membrane lipids. Three other cysteine-containing peptides uniquely bound the surface of apoptotic cells but not viable cells, whereas substitution of alanine for cysteine abolished peptide binding. Several thiol-reactive compounds including N-acetyl-L-cysteine abolished phagocytosis of apoptotic SH-SY5Y cells by macrophages. These data suggest that the P2X(7) receptor in its unactivated state acts like a scavenger receptor, and its extracellular disulphide bonds play an important role in direct recognition and engulfment of apoptotic cells.

Post-fabrication QAC-functionalized thermoplastic polyurethane for contact-killing catheter applications.

PubMed

Zander, Zachary K; Chen, Peiru; Hsu, Yen-Hao; Dreger, Nathan Z; Savariau, Laura; McRoy, Willie C; Cerchiari, Alec E; Chambers, Sean D; Barton, Hazel A; Becker, Matthew L

2018-05-11

The use of catheters is ubiquitous in medicine and the incidence of infection remains unacceptably high despite numerous advances in functional surfaces and drug elution. Herein we report the use of a thermoplastic polyurethane containing an allyl ether side-chain functionality (allyl-TPU) that allows for rapid and convenient surface modification with antimicrobial reagents, post-processing. This post-processing functionalization affords the ability to target appropriate TPU properties and maintain the functional groups on the surface of the device where they do not affect bulk properties. A series of quaternary ammonium thiol compounds (Qx-SH) possessing various hydrocarbon tail lengths (8-14 carbons) were synthesized and attached to the surface using thiol-ene "click" chemistry. A quantitative assessment of the amount of Qx-SH available on the surface was determined using fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS). Contact-killing assays note the Q8-SH composition has the highest antimicrobial activity, and a live/dead fluorescence assay reveals rapid contact-killing of Staphylococcus aureus (>75% in 5 min) and Escherichia coli (90% in 10 min) inocula. Scale-up and extrusion of allyl-TPU provides catheter prototypes for biofilm formation testing with Pseudomonas aeruginosa, and surface-functionalized catheters modified with Q8-SH demonstrate their ability to reduce biofilm formation. Copyright © 2018 Elsevier Ltd. All rights reserved.

The structure, energetics, and nature of the chemical bonding of phenylthiol adsorbed on the Au(111) surface: implications for density-functional calculations of molecular-electronic conduction.

PubMed

Bilić, Ante; Reimers, Jeffrey R; Hush, Noel S

2005-03-01

The adsorption of phenylthiol on the Au(111) surface is modeled using Perdew and Wang density-functional calculations. Both direct molecular physisorption and dissociative chemisorption via S-H bond cleavage are considered as well as dimerization to form disulfides. For the major observed product, the chemisorbed thiol, an extensive potential-energy surface is produced as a function of both the azimuthal orientation of the adsorbate and the linear translation of the adsorbate through the key fcc, hcp, bridge, and top binding sites. Key structures are characterized, the lowest-energy one being a broad minimum of tilted orientation ranging from the bridge structure halfway towards the fcc one. The vertically oriented threefold binding sites, often assumed to dominate molecular electronics measurements, are identified as transition states at low coverage but become favored in dense monolayers. A similar surface is also produced for chemisorption of phenylthiol on Ag(111); this displays significant qualitative differences, consistent with the qualitatively different observed structures for thiol chemisorption on Ag and Au. Full contours of the minimum potential energy as a function of sulfur translation over the crystal face are described, from which the barrier to diffusion is deduced to be 5.8 kcal mol(-1), indicating that the potential-energy surface has low corrugation. The calculated bond lengths, adsorbate charge and spin density, and the density of electronic states all indicate that, at all sulfur locations, the adsorbate can be regarded as a thiyl species that forms a net single covalent bond to the surface of strength 31 kcal mol(-1). No detectable thiolate character is predicted, however, contrary to experimental results for alkyl thiols that indicate up to 20%-30% thiolate involvement. This effect is attributed to the asymptotic-potential error of all modern density functionals that becomes manifest through a 3-4 eV error in the lineup of the adsorbate and substrate bands. Significant implications are described for density-functional calculations of through-molecule electron transport in molecular electronics.

IR spectroscopy study of SBA-15 silicas functionalized with the ethylthiocarbamidepropyl groups and their interactions with Ag(I) and Hg(II) ions

NASA Astrophysics Data System (ADS)

Melnyk, Inna V.; Nazarchuk, Galyna I.; Václavíková, Miroslava; Zub, Yuriy L.

2018-04-01

Mesoporous structure of silica is determined by the type of template, but the introduction of functional groups during the synthesis has additional influence. The structure of SBA-15 may be violated by the introduction of long functions, such as ≡Si(CH2)3NHC(=S)NHC2H5. These ethylthiocarbamidepropyl groups can form complexes with metal ions in thiol or thione tautomeric forms. We determined that the 2D hexagonal p6 mm structure is preserved for SBA-15 with thiourea groups at maximal TEOS:trifunctional silane ratio (mol) = 10:2, which was confirmed by TEM and by the presence of an intense reflex in the small-angle region of diffractograms of the final product. It was shown that the obtained sorbents possess high kinetic characteristics. The experimental data fit pseudo-second-order kinetic equation, but the rate constants depend on the content of functional groups in the surface layer. Template Pluronic P-123 defines the porosity of functional mesoporous silica materials even at increasing content of trifunctional silane in the initial solution. Infrared spectroscopy analysis showed that thione form of thiourea ligand is prevalent on the surface of pores of mesoporous samples. However, during the sorption of silver(I) ions, there are both thione and thiol forms on the surface. Thione form is transformed into thiol with increasing concentration of mercury(II) ions in the sorption solution. Adsorption experiments showed that the SBA-15 silicas functionalized with ethylthiocarbamidepropyl groups had high selectivity for silver(I) ions and could concentrate Ag(I) ions from metal ions mixture at pH 2.

Facile synthesis of terminal-alkyne bioorthogonal molecules for live -cell surface-enhanced Raman scattering imaging through Au-core and silver/dopamine-shell nanotags.

PubMed

Chen, Meng; Zhang, Ling; Yang, Bo; Gao, Mingxia; Zhang, Xiangmin

2018-03-01

Alkyne is unique, specific and biocompatible in the Raman-silent region of the cell, but there still remains a challenge to achieve ultrasensitive detection in living systems due to its weak Raman scattering. Herein, a terminal alkyne ((E)-2-[4-(ethynylbenzylidene)amino]ethane-1-thiol (EBAE)) with surface-enhanced Raman scattering is synthesized. The EBAE molecule possesses S- and C-termini, which can be directly bonded to gold nanoparticles and dopamine/silver by forming the Au-S chemical bond and the carbon-metal bond, respectively. The distance between Raman reporter and AuNPs/AgNPs can be reduced, contributing to forming hot-spot-based SERS substrate. The alkyne functionalized nanoparticles are based on Au core and encapsulating polydopamine shell, defined as Au-core and dopamine/Ag-shell (ACDS). The bimetallic ACDS induce strong SERS signals for molecular imaging that arise from the strong electromagnetic field. Furthermore, the EBAE provides a distinct peak in the cellular Raman-silent region with nearly zero background interference. The EBAE Raman signals could be tremendously enhanced when the Raman reporter is located at the middle of the Au-core and dopamine/Ag-shell. Therefore, this work could have huge potential benefits for the highly sensitive detection of intercellular information delivery by connecting the recognition molecules in biomedical diagnostics. Graphical abstract Terminal-alkyne-functionalized Au-core and silver/dopamine-shell nanotags for live-cell surface-enhanced Raman scattering imaging.

Structural and theoretical basis for ligand exchange on thiolate monolayer protected gold nanoclusters.

PubMed

Heinecke, Christine L; Ni, Thomas W; Malola, Sami; Mäkinen, Ville; Wong, O Andrea; Häkkinen, Hannu; Ackerson, Christopher J

2012-08-15

Ligand exchange reactions are widely used for imparting new functionality on or integrating nanoparticles into devices. Thiolate-for-thiolate ligand exchange in monolayer protected gold nanoclusters has been used for over a decade; however, a firm structural basis of this reaction has been lacking. Herein, we present the first single-crystal X-ray structure of a partially exchanged Au(102)(p-MBA)(40)(p-BBT)(4) (p-MBA = para-mercaptobenzoic acid, p-BBT = para-bromobenzene thiol) with p-BBT as the incoming ligand. The crystal structure shows that 2 of the 22 symmetry-unique p-MBA ligand sites are partially exchanged to p-BBT under the initial fast kinetics in a 5 min timescale exchange reaction. Each of these ligand-binding sites is bonded to a different solvent-exposed Au atom, suggesting an associative mechanism for the initial ligand exchange. Density functional theory calculations modeling both thiol and thiolate incoming ligands postulate a mechanistic pathway for thiol-based ligand exchange. The discrete modification of a small set of ligand binding sites suggests Au(102)(p-MBA)(44) as a powerful platform for surface chemical engineering.

Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

PubMed

Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

2015-09-01

Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

Quartz crystal microbalance (QCM) affinity biosensor for genetically modified organisms (GMOs) detection.

PubMed

Mannelli, Ilaria; Minunni, Maria; Tombelli, Sara; Mascini, Marco

2003-03-01

A DNA piezoelectric sensor has been developed for the detection of genetically modified organisms (GMOs). Single stranded DNA (ssDNA) probes were immobilised on the sensor surface of a quartz crystal microbalance (QCM) device and the hybridisation between the immobilised probe and the target complementary sequence in solution was monitored. The probe sequences were internal to the sequence of the 35S promoter (P) and Nos terminator (T), which are inserted sequences in the genome of GMOs regulating the transgene expression. Two different probe immobilisation procedures were applied: (a) a thiol-dextran procedure and (b) a thiol-derivatised probe and blocking thiol procedure. The system has been optimised using synthetic oligonucleotides, which were then applied to samples of plasmidic and genomic DNA isolated from the pBI121 plasmid, certified reference materials (CRM), and real samples amplified by the polymerase chain reaction (PCR). The analytical parameters of the sensor have been investigated (sensitivity, reproducibility, lifetime etc.). The results obtained showed that both immobilisation procedures enabled sensitive and specific detection of GMOs, providing a useful tool for screening analysis in food samples.

The Role of Follicular Fluid Thiol/Disulphide Homeostasis in Polycystic Ovary Syndrome.

PubMed

Tola, Esra Nur; Köroğlu, Nadiye; Ergin, Merve; Oral, Hilmi Baha; Turgut, Abdülkadir; Erel, Özcan

2018-04-04

Oxidative stress is suggested as a potential triggering factor in the etiopathogenesis of Polycystic ovary syndrome related infertility. Thiol/disulphide homeostasis, a recently oxidative stress marker, is one of the antioxidant mechanism in human which have critical roles in folliculogenesis and ovulation. The aim of our study is to investigate follicular fluid thiol/disulphide homeostasis in the etiopathogenesis of Polycystic ovary syndrome and to determine its' association with in vitro fertilization outcome. The study procedures were approved by local ethic committee. Cross sectional design Methods: Follicular fluid of twenty-two Polycystic ovary syndrome women and twenty ovulatory controls undergoing in vitro fertilization treatment were recruited. Thiol/disulphide homeostasis was analyzed via a novel spectrophotometric method. Follicular native thiol levels were found to be lower in Polycystic ovary syndrome group than non- Polycystic ovary syndrome group (p=0.041) as well as native thiol/total thiol ratio (p<0.0001). Disulphide level, disulphide/native thiol and disulphide/total thiol ratios were increased in Polycystic ovary syndrome group (p<0.0001). A positive correlation between fertilization rate and native thiol (p=0.01, r=0.53) and total thiol (p=0.01, r=0.052) among Polycystic ovary syndrome patients was found. A positive predictive effect of native thiol on fertilization rate among Polycystic ovary syndrome group was also found (p=0.03, β=0.45, 95% CI=0.031-0.643). Deterioration in thiol/disulphide homeostasis, especially elevated disulphide levels could be one of the etiopathogenetic mechanism in Polycystic ovary syndrome. Increased native thiol levels is related to fertilization rate among Polycystic ovary syndrome patients and also positive predictor marker of fertilization rate among Polycystic ovary syndrome patients. Improvement of thiol/disulphide homeostasis could be of importance in the treatment of Polycystic ovary syndrome to increase in vitro fertilization success in Polycystic ovary syndrome.

Facile quantitation of free thiols in a recombinant monoclonal antibody by reversed-phase high performance liquid chromatography with hydrophobicity-tailored thiol derivatization.

PubMed

Welch, Leslie; Dong, Xiao; Hewitt, Daniel; Irwin, Michelle; McCarty, Luke; Tsai, Christina; Baginski, Tomasz

2018-06-02

Free thiol content, and its consistency, is one of the product quality attributes of interest during technical development of manufactured recombinant monoclonal antibodies (mAbs). We describe a new, mid/high-throughput reversed-phase-high performance liquid chromatography (RP-HPLC) method coupled with derivatization of free thiols, for the determination of total free thiol content in an E. coli-expressed therapeutic monovalent monoclonal antibody mAb1. Initial selection of the derivatization reagent used an hydrophobicity-tailored approach. Maleimide-based thiol-reactive reagents with varying degrees of hydrophobicity were assessed to identify and select one that provided adequate chromatographic resolution and robust quantitation of free thiol-containing mAb1 forms. The method relies on covalent derivatization of free thiols in denatured mAb1 with N-tert-butylmaleimide (NtBM) label, followed by RP-HPLC separation with UV-based quantitation of native (disulfide containing) and labeled (free thiol containing) forms. The method demonstrated good specificity, precision, linearity, accuracy and robustness. Accuracy of the method, for samples with a wide range of free thiol content, was demonstrated using admixtures as well as by comparison to an orthogonal LC-MS peptide mapping method with isotope tagging of free thiols. The developed method has a facile workflow which fits well into both R&D characterization and quality control (QC) testing environments. The hydrophobicity-tailored approach to the selection of free thiol derivatization reagent is easily applied to the rapid development of free thiol quantitation methods for full-length recombinant antibodies. Copyright © 2018 Elsevier B.V. All rights reserved.

Metalloproteinase processing of HBEGF is a proximal event in the response of human aortic endothelial cells to oxidized phospholipids.

PubMed

Lee, Sangderk; Springstead, James R; Parks, Brian W; Romanoski, Casey E; Palvolgyi, Roland; Ho, Tiffany; Nguyen, Phuc; Lusis, Aldons J; Berliner, Judith A

2012-05-01

Atherosclerosis is a chronic inflammatory disease initiated by monocyte recruitment and retention in the vessel wall. An important mediator of monocyte endothelial interaction is the chemokine interleukin (IL)-8. The oxidation products of phospholipids, including oxidized 1-palmitoyl-2-arachidonyl-sn-glycerol-3-phosphocholine (Ox-PAPC), accumulate in atherosclerotic lesions and strongly induce IL-8 in human aortic endothelial cells (HAECs). The goal of this study was to identify the proximal events leading to induction of IL-8 by Ox-PAPC in vascular endothelial cells. In a systems genetics analysis of HAECs isolated from 96 different human donors, we showed that heparin-binding EGF-like growth factor (HBEGF) transcript levels are strongly correlated to IL-8 induction by Ox-PAPC. The silencing and overexpression of HBEGF in HAECs confirmed the role of HBEGF in regulating IL-8 expression. HBEGF has been shown to be stored in an inactive form and activation is dependent on processing by a dysintegrin and metalloproteinases (ADAM) to a form that can activate the epidermal growth factor (EGF) receptor. Ox-PAPC was shown to rapidly induce HBEGF processing and EGF receptor activation in HAECs. Using siRNA we identified 3 ADAMs that regulate IL-8 induction and directly demonstrated that Ox-PAPC increases ADAM activity in the cells using a substrate cleavage assay. We provide evidence for one mechanism of Ox-PAPC activation of ADAM involving covalent binding of Ox-PAPC to cysteine on ADAM. Free thiol cysteine analogs showed inhibition of IL-8 induction by Ox-PAPC, and both a cysteine analog and a cell surface thiol blocker strongly inhibited ADAM activity induction by Ox-PAPC. Using microarray analyses, we determined that this ADAM pathway may regulate at least 30% of genes induced by Ox-PAPC in HAECs. This study is the first report demonstrating a role for the ADAM-HBEGF-EGF receptor axis in Ox-PAPC induction of IL-8 in HAECs. These studies highlight a role for specific ADAMs as initiators of Ox-PAPC action and provide evidence for a role of covalent interaction of Ox-PAPC in activation of ADAMs.

Metalloproteinase processing of HBEGF is a proximal event in the response of human aortic endothelial cells to oxidized phospholipids

PubMed Central

Lee, Sangderk; Springstead, James R.; Parks, Brian; Romanoski, Casey E.; Palvolgyi, Roland; Ho, Tiffany; Nguyen, Phuc; Lusis, Aldons J.; Berliner, Judith A.

2012-01-01

Objective Atherosclerosis is a chronic inflammatory disease initiated by monocyte recruitment and retention in the vessel wall. An important mediator of monocyte endothelial interaction is the chemokine IL-8. The oxidation products of phospholipids, including Ox-PAPC, accumulate in atherosclerotic lesions and strongly induce IL-8 in human aortic endothelial cells (HAECs). The goal of this study was to identify the proximal events leading to induction of IL-8 by Ox-PAPC in vascular endothelial cells. Methods and Results In a systems genetics analysis of HAECs isolated from 96 different human donors, we showed that HBEGF transcript levels are strongly correlated to IL-8 induction by Ox-PAPC. The silencing and overexpression of HBEGF in HAECs confirmed the role of HBEGF in regulating IL-8 expression. HBEGF has been shown to be stored in an inactive form and activation is dependent on processing by a dysintegrin and metalloproteinases (ADAM) to a form that can activate EGF receptor (EGFR). Ox-PAPC was shown to rapidly induce HBEGF processing and EGFR activation in HAECs. Using siRNA we identified three ADAMs that regulate IL-8 induction and directly demonstrated that Ox-PAPC increases ADAM activity in the cells by substrate cleavage assay. We provide evidence for one mechanism of Ox-PAPC activation of ADAM involving covalent binding of Ox-PAPC to cysteine on ADAM. Free thiol cysteine analogs showed inhibition of IL-8 induction by Ox-PAPC, and both a cysteine analog and a cell surface thiol blocker strongly inhibited ADAM activity induction by Ox-PAPC. Using microarray analyses, we determined that this ADAM pathway may regulate as much as 30% of genes induced by Ox-PAPC in HAECs. Conclusion This study is the first report demonstrating a role for the ADAM-HBEGF-EGFR axis in Ox-PAPC induction of IL-8 in HAECs. These studies highlight a role for specific ADAMs as initiators of Ox-PAPC action and provide evidence for a role of covalent interaction of Ox-PAPC in activation of ADAMs. PMID:22402363

Single-molecule optical-trapping measurements with DNA anchored to an array of gold nanoposts.

PubMed

Paik, D Hern; Perkins, Thomas T

2012-01-01

Gold-thiol chemistry is one of the most successful chemistries for conjugating biomolecules to surfaces, but such chemistry has not been exploited in optical-trapping experiments because of laser-induced ablation of gold. In this work, we describe a method to combine these two separate technologies without undue heating using DNA anchored to gold nanostructures (r = 50-250 nm; h ≈ 20 nm). Moreover, we demonstrate a quantitative and mechanically robust (>100 pN) optical-trapping assay. By using three dithiol phosphoramidites (DTPAs) incorporated into a polymerase chain reaction (PCR) primer, the gold-DNA bond remained stable in the presence of excess thiolated compounds. This chemical robustness allowed us to reduce nonspecific sticking by passivating the unreacted gold with methoxy-(polyethylene glycol)-thiol (mPEG-SH). Overall, this surface conjugation of biomolecules onto an ordered array of gold nanostructures by chemically and mechanically robust bonds provides a unique way to carry out spatially controlled, repeatable measurements of single molecules.

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Chang, Jeong Ho; Kang, Ki Ho; Choi, Jinsub; Jeong, Young Keun

2008-10-01

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of 10-40 nm by a sol-gel approach. The surface modification was performed with four kinds of functionalized organosilanes such as carboxyl, aldehyde, amine, and thiol groups. The protein separation work with organosilane assembled silica coated magnetic nanoparticles was achieved for model proteins such as bovine serum albumin (BSA) and lysozyme (LSZ) at different pH conditions. Among the various functionalities, the thiol group showed good separation efficiency due to the change of electrostatic interactions and protein conformational structure. The adsorption efficiency of BSA and LSZ was up to 74% and 90% corresponding pH 4.65 and pH 11.

Poly(ethylene glycol) analogs grafted with low molecular weight poly(ethylene imine) as non-viral gene vectors.

PubMed

Zhang, Zhenfang; Yang, Cuihong; Duan, Yajun; Wang, Yanming; Liu, Jianfeng; Wang, Lianyong; Kong, Deling

2010-07-01

A novel class of non-viral gene vectors consisting of low molecular weight poly(ethylene imine) (PEI) (molecular weight 800 Da) grafted onto degradable linear poly(ethylene glycol) (PEG) analogs was synthesized. First, a Michael addition reaction between poly(ethylene glycol) diacrylates (PEGDA) (molecular weight 258 Da) and d,l-dithiothreitol (DTT) was carried out to generate a linear polymer (PEG-DTT) having a terminal thiol, methacrylate and pendant hydroxyl functional groups. Five PEG-DTT analogs were synthesized by varying the molar ratio of diacrylates to thiols from 1.2:1 to 1:1.2. Then PEI (800 Da) was grafted onto the main chain of the PEG-DTTs using 1,1'-carbonyldiimidazole as the linker. The above reaction gave rise to a new class of non-viral gene vectors, (PEG-DTT)-g-PEI copolymers, which can effectively complex DNA to form nanoparticles. The molecular weights and structures of the copolymers were characterized by gel permeation chromatography, (1)H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The size of the nanoparticles was<200 nm and the surface charge of the nanoparticles, expressed as the zeta potential, was between+20 and+40 mV. Cytotoxicity assays showed that the copolymers exhibited much lower cytotoxicities than high molecular weight PEI (25 kDa). Transfection was performed in cultured HeLa, HepG2, MCF-7 and COS-7 cells. The copolymers showed higher transfection efficiencies than PEI (25 kDa) tested in four cell lines. The presence of serum (up to 30%) had no inhibitory effect on the transfection efficiency. These results indicate that this new class of non-viral gene vectors may be a promising gene carrier that is worth further investigation. Copyright 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A crucial role for thiol antioxidants in estrogen-deficiency bone loss

PubMed Central

Lean, Jenny M.; Davies, Julie T.; Fuller, Karen; Jagger, Christopher J.; Kirstein, Barrie; Partington, Geoffrey A.; Urry, Zoë L.; Chambers, Timothy J.

2003-01-01

The mechanisms through which estrogen prevents bone loss are uncertain. Elsewhere, estrogen exerts beneficial actions by suppression of reactive oxygen species (ROS). ROS stimulate osteoclasts, the cells that resorb bone. Thus, estrogen might prevent bone loss by enhancing oxidant defenses in bone. We found that glutathione and thioredoxin, the major thiol antioxidants, and glutathione and thioredoxin reductases, the enzymes responsible for maintaining them in a reduced state, fell substantially in rodent bone marrow after ovariectomy and were rapidly normalized by exogenous 17-β estradiol. Moreover, administration of N-acetyl cysteine (NAC) or ascorbate, antioxidants that increase tissue glutathione levels, abolished ovariectomy-induced bone loss, while L-buthionine-(S,R)-sulphoximine (BSO), a specific inhibitor of glutathione synthesis, caused substantial bone loss. The 17-β estradiol increased glutathione and glutathione and thioredoxin reductases in osteoclast-like cells in vitro. Furthermore, in vitro NAC prevented osteoclast formation and NF-κB activation. BSO and hydrogen peroxide did the opposite. Expression of TNF-α, a target for NF-κB and a cytokine strongly implicated in estrogen-deficiency bone loss, was suppressed in osteoclasts by 17-β estradiol and NAC. These observations strongly suggest that estrogen deficiency causes bone loss by lowering thiol antioxidants in osteoclasts. This directly sensitizes osteoclasts to osteoclastogenic signals and entrains ROS-enhanced expression of cytokines that promote osteoclastic bone resorption. PMID:12975476

Two methods for one-point anchoring of a linear polysaccharide on a gold surface.

PubMed

Hoypierres, Julia; Dulong, Virginie; Rihouey, Christophe; Alexandre, Stéphane; Picton, Luc; Thébault, Pascal

2015-01-01

Two strategies to achieve a one-point anchoring of a hydrolyzed pullulan (P9000) on a gold surface are compared. The first strategy consists of forming a self-assembled monolayer of a 6-amino-1-hexanethiol (AHT) and then achieving reductive amination on the surface between the aminated surface and the aldehyde of the polysaccharide reductive end sugar. The second consists of incorporating a thiol function at the extremity of the pullulan (via the same reductive amination), leading to P9000-AHT and then immobilizing it on gold by a spontaneous reaction between solid gold and thiol. The modified pullulan was characterized by NMR and size-exclusion chromatography coupled to a light-scattering detector. P9000-AHT appears to be in a disulfide dimer form in solution but recovers its unimer form with dithiothreitol (DTT) treatment. The comparison of the two strategies by contact angle and XPS revealed that the second strategy is more efficient for the pullulan one-point anchoring. P9000-AHT even in its dimer form is easily grafted onto the surface. The grafted polymer seems to be more in a coil conformation than in a rigid brush. Furthermore, QCM measurements highlighted that the second strategy leads to a grafting density of around 3.5 × 10(13) molecules·cm(-2) corresponding to a high surface coverage. The elaboration of a dense and oriented layer of polysaccharides covalently linked to a gold surface might enhance the use of such modified polysaccharides in various fields.

Mangiferin, a natural occurring glucosyl xanthone, increases susceptibility of rat liver mitochondria to calcium-induced permeability transition.

PubMed

Andreu, Gilberto Lázaro Pardo; Delgado, René; Velho, Jesus Antonio; Curti, Carlos; Vercesi, Anibal E

2005-07-15

Mitochondrial permeability transition (MPT) is a Ca(2+)-dependent, cyclosporine A-sensitive, non-selective inner membrane permeabilization induced by a wide range of agents or conditions, which has often been associated with necrotic or apoptotic cell death. When mitochondria isolated from livers of rats treated with the natural occurring glucosyl xanthone mangiferin (40 mg/kg body weight) were exposed in vitro to Ca(2+), they underwent CsA, NEM, and ADP-sensitive high amplitude swelling and associated membrane potential dissipation, release of pre-accumulated Ca(2+), oxidation of thiol groups, and depletion of GSH, without changes in the NAD(P)H redox state. The same treatment reduced the phosphorylation rate of mitochondria and the resting respiration by around 4 and 11%, respectively, as well as generation of reactive oxygen species (ROS) by organelle. The in vitro exposure of untreated mitochondria to mangiferin plus Ca(2+) also resulted in oxidation of thiol groups, in the same way that the compound inhibited the Ca(2+)-induced peroxidation of mitochondrial membrane lipids. The spectrum of mangiferin during its oxidation by the H(2)O(2)/HRP system showed a characteristic absorption peak at 380 nm, which decreased immediately after reaction was started; two isosbestic points at around 336 and 412 nm, with a blue shift in the position of the maxima absorption of mangiferin were observed, suggesting their conversion into one oxidation product. Glutathione abolished this decrease of absorbance, suggesting that the oxidation product of mangiferin forms adducts with GSH. We propose that Ca(2+) increases levels of mitochondria-generated ROS, which reacts with mangiferin producing quinoid derivatives, which in turn react with the most accessible mitochondrial thiol groups, thus triggering MPT. It seems probable that the free radical scavenging activity of mangiferin shifts its anti-oxidant protection to the thiol arylation. An interesting proposition is that accumulation of mangiferin quinoid products would take place in cells exposed to an overproduction of ROS, such as cancer cells, where the occurrence of MPT-mediated apoptosis may be a cellular defence mechanism against excessive ROS formation.

The evolution of glutathione metabolism in phototrophic microorganisms

NASA Technical Reports Server (NTRS)

Fahey, R. C.; Buschbacher, R. M.; Newton, G. L.

1987-01-01

Of the many roles ascribed to glutathione (GSH) the one most clearly established is its role in the protection of higher eucaryotes against oxygen toxicity through destruction of thiol-reactive oxygen byproducts. If this is the primary function of GSH then GSH metabolism should have evolved during or after the evolution of oxygenic photosynthesis. That many bacteria do not produce GSH is consistent with this view. In the present study we have examined the low-molecular-weight thiol composition of a variety of phototrophic microorganisms to ascertain how evolution of GSH production is related to evolution of oxygenic photosynthesis. Cells were extracted in the presence of monobromobimane (mBBr) to convert thiols to fluorescent derivatives, which were analyzed by high-pressure liquid chromatography. Significant levels of GSH were not found in the green bacteria (Chlorobium thiosulfatophilum and Chloroflexus aurantiacus). Substantial levels of GSH were present in the purple bacteria (Chromatium vinosum, Rhodospirillum rubrum, Rhodobacter sphaeroides, and Rhodocyclus gelatinosa), the cyanobacteria [Anacystis nidulans, Microcoleus chthonoplastes S.G., Nostoc muscorum, Oscillatoria amphigranulata, Oscillatoria limnetica, Oscillatoria sp. (Stinky Spring, Utah), Oscillatoria terebriformis, Plectonema boryanum, and Synechococcus lividus], and eucaryotic algae (Chlorella pyrenoidsa, Chlorella vulgaris, Euglena gracilis, Scenedesmus obliquus, and Chlamydomonas reinhardtii). Other thiols measured included cysteine, gamma-glutamylcysteine, thiosulfate, coenzyme A, and sulfide; several unidentified thiols were also detected. Many of the organisms examined also exhibited a marked ability to reduce mBBr to syn-(methyl,methyl)bimane, an ability that was quenched by treatment with 2-pyridyl disulfide or 5,5'-bisdithio-(2-nitrobenzoic acid) prior to reaction with mBBr. These observations indicate the presence of a reducing system capable of electron transfer to mBBr and reduction of reactive disulfides. The distribution of GSH in phototrophic eubacteria indicates that GSH synthesis evolved at or around the time that oxygenic photosynthesis evolved.

Glutamine Supplementation Attenuates Ethanol-Induced Disruption of Apical Junctional Complexes in Colonic Epithelium and Ameliorates Gut Barrier Dysfunction and Fatty Liver in Mice

PubMed Central

Chaudhry, Kamaljit K.; Shukla, Pradeep K.; Mir, Hina; Manda, Bhargavi; Gangwar, Ruchika; Yadav, Nikki; McMullen, Megan; Nagy, Laura E.; Rao, RadhaKrishna

2015-01-01

Previous in vitro studies showed that glutamine (Gln) prevents acetaldehyde-induced disruption of tight junctions and adherens junctions in Caco-2 cell monolayers and human colonic mucosa. In the present study, we evaluated the effect of Gln supplementation on ethanol-induced gut barrier dysfunction and liver injury in mice in vivo. Ethanol feeding caused a significant increase in inulin permeability in distal colon. Elevated permeability was associated with a redistribution of tight junction and adherens junction proteins and depletion of detergent-insoluble fractions of these proteins, suggesting that ethanol disrupts apical junctional complexes in colonic epithelium and increases paracellular permeability. Ethanol-induced increase in colonic mucosal permeability and disruption of junctional complexes were most severe in mice fed Gln-free diet. Gln supplementation attenuated ethanol-induced mucosal permeability and disruption of tight junctions and adherens junctions in a dose-dependent manner, indicating the potential role of glutamine in nutritional intervention to alcoholic tissue injury. Gln supplementation dose-dependently elevated reduced-protein thiols in colon without affecting the level of oxidized-protein thiols. Ethanol feeding depleted reduced protein thiols and elevated oxidized protein thiols. Ethanol-induced protein thiol oxidation was most severe in mice fed Gln-free diet and absent in mice fed Gln-supplemented diet, suggesting that antioxidant effect is one of the likely mechanisms involved in Gln-mediated amelioration of ethanol-induced gut barrier dysfunction. Ethanol feeding elevated plasma transaminase and liver triglyceride, which was accompanied by histopathologic lesions in the liver; ethanol-induced liver damage was attenuated by Gln supplementation. These results indicate that Gln supplementation ameliorates alcohol-induced gut and liver injury. PMID:26365579

Synthesis of cyclic, multivalent Arg-Gly-Asp using sequential thiol-ene/thiol-yne photoreactions

PubMed Central

Aimetti, Alex A.; Feaver, Kristen R.

2014-01-01

A unique method has been developed for the formation of multivalent cyclic peptides. This procedure exploits on-resin peptide cyclization using a photoinitiated thiol-ene click reaction and subsequent clustering using thiol-yne photochemistry. Both reactions utilize the sulfhydryl group on natural cysteine amino acids to participate in the thiol-mediated reactions. PMID:20552127

Molecular Characterization of Thiols in Fossil Fuels by Michael Addition Reaction Derivatization and Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry.

PubMed

Wang, Meng; Zhao, Suoqi; Liu, Xuxia; Shi, Quan

2016-10-04

Thiols widely occur in sediments and fossil fuels. However, the molecular composition of these compounds is unclear due to the lack of appropriate analytical methods. In this work, a characterization method for thiols in fossil fuels was developed on the basis of Michael addition reaction derivatization followed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Model thiol compound studies showed that thiols were selectively reacted with phenylvinylsulfone and transformed to sulfones with greater than 98% conversions. This method was applied to a coker naphtha, light and heavy gas oils, and crude oils from various geological sources. The results showed that long alkyl chain thiols are readily present in petroleum, which have up to 30 carbon atoms. Large DBE dispersity of thiols indicates that naphthenic and aromatic thiols are also present in the petroleum. This method is capable of detecting thiol compounds in the part per million range by weight. This method allows characterization of thiols in a complex hydrocarbon matrix, which is complementary to the comprehensive analysis of sulfur compounds in fossil fuels.

Thiol/disulfide homeostasis in postmenopausal osteoporosis.

PubMed

Korkmaz, V; Kurdoglu, Z; Alisik, M; Turgut, E; Sezgın, O O; Korkmaz, H; Ergun, Y; Erel, O

2017-04-01

To evaluate the impact of postmenopausal osteoporosis on thiol/disulfide homeostasis. A total of 75 participants were divided into two groups: Group 1 (n = 40) was composed of healthy postmenopausal women, and group 2 (n = 35) was composed of women with postmenopausal osteoporosis. Clinical findings and thiol/disulfide homeostasis were compared between the two groups. The disulfide/native thiol ratio was 8.6% ± 3.6 in group 1 and 12.7% ± 8.4 in group 2 (p = 0.04). The disulfide/native thiol percent ratio was significantly higher in group 2 after adjustment for the years since menopause and age (p < 0.05). The native thiol/total thiol percent ratio was 85.6% ± 4.8 in group 1 and 73.8% ± 24.9 in group 2 (p = 0.01). The native thiol/total thiol percent ratio was significantly lower in group 2 after adjustment for the years since menopause and age (p < 0.05). Thiol/disulfide homeostasis shifted to the disulfide side independent of age and years since menopause in postmenopausal osteoporosis.

Unexpected effects of gene deletion on mercury interactions with the methylation-deficient mutant hgcAB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Hui; Hurt, Jr., Richard Ashley; Johs, Alexander

2014-01-01

The hgcA and hgcB gene pair is essential for mercury (Hg) methylation by certain anaerobic bacteria,1 but little is known about how deletion of hgcAB affects cell surface interactions and intracellular uptake of Hg. Here, we compare hgcAB mutants with the wild-type (WT) strains of both Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132 and observe differences in Hg redox transformations, adsorption, and uptake in laboratory incubation studies. In both strains, deletion of hgcAB increased the reduction of Hg(II) but decreased the oxidation of Hg(0) under anaerobic conditions. The measured cellular thiol content in hgcAB mutants was lower than the WT,more » accounting for decreased adsorption and uptake of Hg. Despite the lack of methylation activity, Hg uptake by the hgcAB continued, albeit at a slower rate than the WT. These findings demonstrate that deletion of the hgcAB gene not only eliminates Hg methylation but also alters cell physiology, resulting in changes to Hg redox reactions, sorption, and uptake by cells.« less

Synthesis and in vitro characterization of a novel S-protected thiolated alginate.

PubMed

Hauptstein, Sabine; Dezorzi, Stefanie; Prüfert, Felix; Matuszczak, Barbara; Bernkop-Schnürch, Andreas

2015-06-25

The object of this study was to synthesize and characterize a novel S-protected thiolated polymer with a high degree of modification. In this regard, an alginate-cysteine and an alginate-cysteine-2-mercaptonicotinic acid conjugate were synthesized. To achieve a high coupling rate of the thiol group bearing ligand cysteine to the polymer, the carbohydrate was activated by an oxidative ring opening with sodium periodate followed by a reductive amination to bind the primary amino group of cysteine to resulting reactive aldehyde groups. The obtained thiolated polymer displayed 1561±130μmol thiol groups per gram polymer. About one third of these thiol groups were S-protected by the implementation of a thiol bearing aromatic protection group via disulfide bond formation. Test tablets of both modified polymers showed improved stability against oxidation in aqueous environment compared to the unmodified alginate and exhibit higher water-uptake capacity. Rheological investigations revealed an increased viscosity of the S-protected thiolated polymer whereat the thiolated non S-protected polymer showed gelling properties after the addition of hydrogen peroxide. The mucoadhesive properties could be improved significantly for both derivatives and no alteration in biocompatibility tested on Caco-2 cell monolayer employing an MTT assay could be detected after modification. According to these results, both new derivatives seem promising for various applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

A physical/psychological and biological stress combine to enhance endoplasmic reticulum stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondal, Tapan Kumar; Emeny, Rebecca T.; Gao, Donghong

The generation of an immune response against infectious and other foreign agents is substantially modified by allostatic load, which is increased with chemical, physical and/or psychological stressors. The physical/psychological stress from cold-restraint (CR) inhibits host defense against Listeria monocytogenes (LM), due to early effects of the catecholamine norepinephrine (NE) from sympathetic nerves on β1-adrenoceptors (β1AR) of immune cells. Although CR activates innate immunity within 2 h, host defenses against bacterial growth are suppressed 2–3 days after infection (Cao and Lawrence 2002). CR enhances inducible nitric oxide synthase (iNOS) expression and NO production. The early innate activation leads to cellular reduction-oxidationmore » (redox) changes of immune cells. Lymphocytes from CR-treated mice express fewer surface thiols. Splenic and hepatic immune cells also have fewer proteins with free thiols after CR and/or LM, and macrophages have less glutathione after the in vivo CR exposure or exposure to NE in vitro. The early induction of CR-induced oxidative stress elevates endoplasmic reticulum (ER) stress, which could interfere with keeping phagocytized LM within the phagosome or re-encapsuling LM by autophagy once they escape from the phagosome. ER stress-related proteins, such as glucose-regulated protein 78 (GRP78), have elevated expression with CR and LM. The results indicate that CR enhances the unfolded protein response (UPR), which interferes with host defenses against LM. Thus, it is postulated that increased stress, as exists with living conditions at low socioeconomic conditions, can lower host defenses against pathogens because of oxidative and ER stress processes. - Highlights: • Cold-restraint (physical/psychological stress) induces early oxidative stress. • The oxidative stress relates to catecholamine signaling beta-adrenoceptors. • Physical/psychological stress combines infection enhancing inflammation. • Endoplasmic reticulum stress interferes with host defenses and autophagy.« less

Toxicity and oxidative stress induced by semiconducting polymer dots in RAW264.7 mouse macrophages

NASA Astrophysics Data System (ADS)

Ye, Fangmao; White, Collin C.; Jin, Yuhui; Hu, Xiaoge; Hayden, Sarah; Zhang, Xuanjun; Gao, Xiaohu; Kavanagh, Terrance J.; Chiu, Daniel T.

2015-05-01

The rapid development and acceptance of PDots for biological applications depends on an in depth understanding of their cytotoxicity. In this paper, we performed a comprehensive study of PDot cytotoxicity at both the gross cell effect level (such as cell viability, proliferation and necrosis) and more subtle effects (such as redox stress) on RAW264.7 cells, a murine macrophage cell line with high relevance to in vivo nanoparticle disposition. The redox stress measurements assessed were inner mitochondrial membrane lipid peroxidation (nonyl-acridine orange, NAO), total thiol level (monobromobimane, MBB), and pyridine nucleotide redox status (NAD(P)H autofluorescence). Because of the extensive work already performed with QDots on nanotoxicity and also because of their comparable size, QDots were chosen as a comparison/reference nanoparticle for this study. The results showed that PDots exhibit cytotoxic effects to a much lesser degree than their inorganic analogue (QDots) and are much brighter, allowing for much lower concentrations to be used in various biological applications. In addition, at lower dose levels (2.5 nM to 10 nM) PDot treatment resulted in higher total thiol level than those found with QDots. At higher dose levels (20 nM to 40 nM) QDots caused significantly higher thiol levels in RAW264.7 cells, than was seen with PDots, suggesting that QDots elicit compensation to oxidative stress by upregulating GSH synthesis. At the higher concentrations of QDots, NAD(P)H levels showed an initial depletion, then repletion to a level that was greater than vehicle controls. PDots showed a similar trend but this was not statistically significant. Because PDots elicit less oxidative stress and cytotoxicity at low concentrations than QDots, and because they exhibit superior fluorescence at these low concentrations, PDots are predicted to have enhanced utility in biomedical applications.

Patterning of Biomolecules on Plasma-Enhanced Chemical Vapor Deposited Generated Surfaces

DTIC Science & Technology

2006-01-01

utilized conventional 1 -Ethyl- 3 -[ 3 - dimethylaminopropyl ]carbodiimide hydrochloride (EDC) to couple carboxyl groups to primary amines and thiol oxidation...RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YY) 2. REPORT TYPE 3 . DATES COVERED (From - To) January 2006 Journal Article Preprint...morphology, allowing for robust surface deposited 3 materials. More specifically, bulk pp-benzene shows less than 1 % sol fraction when immersed in

Facile Synthesis of Thick Films of Poly(methyl methacrylate), Poly(styrene), and Poly(vinyl pyridine) from Au Surfaces

PubMed Central

Saha, Sampa

2011-01-01

Atom transfer radical polymerization (ATRP) is commonly used to grow polymer brushes from Au surfaces, but the resulting film thicknesses are usually significantly less than with ATRP from SiO2 substrates. On Au, growth of poly(methyl methacrylate) (PMMA) blocks from poly(tert-butyl acrylate) brushes occurs more rapidly than growth of PMMA from initiator monolayers, suggesting that the disparity between growth rates from Au and SiO2 stems from the Au surface. Radical quenching by electron transfer from Au is probably not the termination mechanism because polymerization from thin, cross-linked initiators gives film thicknesses that are essentially the same as the thicknesses of films grown from SiO2 under the same polymerization conditions. However, this result is consistent with termination through desorption of thiols from non-cross-linked films, and reaction of these thiols with growing polymer chains. The enhanced stability of cross-linked initiators allows ATRP at temperatures up to ~100 °C and enables the growth of thick films of PMMA (350 nm), polystyrene (120 nm) and poly(vinyl pyridine) (200 nm) from Au surfaces in 1 hour. At temperatures >100 °C, the polymer brush layers delaminate as large area films. PMID:21728374

Thiol/disulfide homeostasis in patients with ankylosing spondylitis

PubMed Central

Dogru, Atalay; Balkarli, Ayse; Cetin, Gozde Yildirim; Neselioglu, Salim; Erel, Ozcan; Tunc, Sevket Ercan; Sahin, Mehmet

2016-01-01

Ankylosing spondylitis (AS) is a chronic inflammatory disease. In many inflammatory diseases, increased production of pro-inflammatory cytokines is associated with an increase in oxidative stress mediators. Thiol/disulfide homeostasis is a marker for oxidative stress. The aim of this study was to examine the dynamic thiol/disulfide homeostasis in AS. Sixty-nine patients with AS and 60 age- and sex-matched controls were included in the study. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and visual analogue scale (VAS) were used to determine the disease activity. Native thiol, total thiol, and disulfide levels were measured with a novel automated method recently described by Erel and Neselioglu. The aforementioned method is also optionally manual spectrophotometric assay. The total thiol levels were significantly lower in the AS group compared with the control group (p = 0.03). When the patients were divided into active (n = 35) and inactive (n = 34) subgroups using BASDAI scores, the native plasma thiol and total thiol levels were significantly lower in the active AS patients compared to the inactive AS patients (p = 0.02, p = 0.03 respectively). There was a negative correlation between the plasma native thiol levels and VAS, BASDAI scores. Thiol/disulfide homeostasis may be used for elucidating the effects of oxidative stress in AS. Understanding the role of thiol/disulfide homeostasis in AS might provide new therapeutic intervention strategies for patients. PMID:27186972

Cinder Pool's Sulfur Chemistry: Implications for the Origin of Life in Hydrothermal Environments

NASA Astrophysics Data System (ADS)

Sydow, L.; Bennett, P.; Nordstrom, D.

2012-12-01

One theory of the origin of life posits the abiotic formation of alkyl thiols as an initial step to forming biomolecules and eventually a simple chemoautotrophic cell. The premise of this theory is that a recurring reaction on the charged surfaces of pyrite served as a primordial metabolism analogous to the Acetyl-CoA pathway (Wächtershäuser 1988) and was later enveloped by a primitive cellular membrane. However, alkyl thiols have not previously been identified in terrestrial hot springs as unequivocally abiogenic. We have identified methanethiol (CH3SH), the simplest of the alkyl thiols, as well as dimethyl sulfide and dimethyldisulfide, in Cinder Pool, an acid-sulfate-chloride hot spring in the One Hundred Spring Plain of Norris Geyser Basin, Yellowstone National Park. It is unusual in that it contains a molten sulfur layer on the bottom (~20 m depth) and thousands of iron-sulfur-spherules floating on the surface (the iconic "cinders" the pool is named for), created by gas bubbling through the molten basement of the spring. These unique features make it a good candidate for abiotically generated CH3SH. Gas samples were collected from Cinder pool as well as an adjacent hydrothermal feature in the autumn of 2011 using the bubble strip method modified for use with hydrothermal waters. Several samples contained measurable quantities of methanethiol and other organic sulfur gases, with concentrations increasing with depth in the pool. Laboratory microcosm experiments were conducted to investigate the geochemical conditions required to abiotically form CH3SH. Sterile, artificial Cinder Pool water was injected into sterilized 60 mL serum bottles containing different iron-sulfur compounds, including cinders collected from the pool itself, as catalytic surfaces for the methanethiol-generating reaction. The bottles were then charged with hydrogen and carbon dioxide as reaction gases and incubated for a week at temperatures between 60 and 120oC. Bottles using FeS as a catalytic surface consistently produced methanethiol as expected from previous work. Bottles containing pyrite or cinders also generated lower but measurable quantities of CH3SH. While CH3SH is central to the autotroph-first theory and has been synthesized in the laboratory (e.g. Heinen and Lauwers 1996), it has not previously been observed to form abiotically in natural systems (although it is a common microbial byproduct of sulfur metabolism). We have identified CH3SH in a natural hydrothermal feature where it is unlikely to have formed secondary to microbial activity, as the only microorganism found in Cinder Pool is Aquificales Hydrogenobaculum (Spear et al. 2005) which can oxidize reduced sulfur compounds and would use methanethiol as a substrate, but should not form it as a byproduct. We have duplicated our field findings in sterile laboratory experiments using the cinders as a reactive surface. Also of note, the autotroph-first theory suggests that the primitive cellular membrane that enclosed the first metabolism was an FeS bubble created by a redox front (Russell and Hall 1997). While the cinders are not purely FeS, they could potentially serve this purpose based on the material's ability to function as a catalytic surface.

Allicin-inspired thiolated fluoroquinolones as antibacterials against ESKAPE pathogens.

PubMed

Sheppard, Jordan G; Long, Timothy E

2016-11-15

Thiolated fluoroquinolones were synthesized from ciprofloxacin and evaluated for antimicrobial activity against a panel of pathogenic bacteria. Gram-positive species including methicillin-resistant Staphylococcus aureus (MRSA) exhibited the highest level of increased sensitivity toward ciprofloxacin bound with a N-propylthio substituent. Evidence was found that the antibiotics form disulfides with low molecular weight thiols in bacteria and potentiate generation of cytosolic reactive oxygen species (ROS). In final analysis, the enhanced anti-MRSA activity of thiolated fluoroquinolones was attributed to increased cell permeability and reaction with cytosolic thiols that yields an inactive disulfide metabolite and the parent drug ciprofloxacin as an inhibitor of DNA synthesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal optical nonlinearity in photonic crystal fibers filled with nematic liquid crystals doped with gold nanoparticles

NASA Astrophysics Data System (ADS)

Lesiak, Piotr; Budaszewski, Daniel; Bednarska, Karolina; Wójcik, Michał; Sobotka, Piotr; Chychłowski, Miłosz; Woliński, Tomasz R.

2017-05-01

In this work we studied a newly reported class of nonlinear effects observed in 5CB liquid crystals doped with gold nanoparticles (GNPs). The size of the GNP was determined by direct TEM imaging and by X-ray scattering of the diluted NP solution. GNPs was coated by thiols with the ratio of mesogenic to n-alkyl thiols varying from 1:2 to 1:1. The research involved comparing properties of both undoped and doped 5CB (nematic LC) by infiltrating LC cell and microholes of the photonic crystal fiber (PCF) separately. In our experiment the PCF fiber type LMA-10 made by NKT Photonics as host material has been used.

Gel Permeation Chromatography Characterization of the Chain Length Distributions in Thiol-Acrylate Photopolymer Networks

PubMed Central

Rydholm, Amber E.; Held, Nicole L.; Bowman, Christopher N.; Anseth, Kristi S.

2008-01-01

Crosslinked, degradable networks formed from the photopolymerization of thiol and acrylate monomers are explored as potential biomaterials. The degradation behavior and material properties of these networks are influenced by the molecular weight of the nondegradable thiol-polyacrylate backbone chains that form during photopolymerization. Here, gel permeation chromatography was used to characterize the thiol-polyacrylate backbone chain lengths in degraded thiol-acrylate networks. Increasing thiol functionality from 1 to 4 increased the backbone molecular weight (M̄w = 2.3 ± 0.07 × 104 Da for monothiol and 3.6 ± 0.1 × 104 Da for tetrathiol networks). Decreasing thiol functional group concentration from 30 to 10 mol% also increased the backbone lengths (M̄w = 7.3 ± 1.1 × 104 Da for the networks containing 10 mol% thiol groups as compared to 3.6 ± 0.1 × 104 Da for 30 mol% thiol). Finally, the backbone chain lengths were probed at various stages of degradation and an increase in backbone molecular weight was observed as mass loss progressed from 10 to 70%. PMID:19079733

Quantitative real-time imaging of glutathione

USDA-ARS?s Scientific Manuscript database

Glutathione plays many important roles in biological processes; however, the dynamic changes of glutathione concentrations in living cells remain largely unknown. Here, we report a reversible reaction-based fluorescent probe—designated as RealThiol (RT)—that can quantitatively monitor the real-time ...

Removal of heavy metals from aqueous systems with thiol functionalized superparamagnetic nanoparticles.

PubMed

Yantasee, Wassana; Warner, Cynthia L; Sangvanich, Thanapon; Addleman, R Shane; Carter, Timothy G; Wiacek, Robert J; Fryxell, Glen E; Timchalk, Charles; Warner, Marvin G

2007-07-15

We have shown that superparamagnetic iron oxide (Fe3O4) nanoparticles with a surface functionalization of dimercaptosuccinic acid (DMSA) are an effective sorbent material for toxic soft metals such as Hg, Ag, Pb, Cd, and Tl, which effectively bind to the DMSA ligands and for As, which binds to the iron oxide lattices. The nanoparticles are highly dispersible and stable in solutions, have a large surface area (114 m2/g), and have a high functional group content (1.8 mmol thiols/g). They are attracted to a magnetic field and can be separated from solution within a minute with a 1.2 T magnet. The chemical affinity, capacity, kinetics, and stability of the magnetic nanoparticles were compared to those of conventional resin based sorbents (GT-73), activated carbon, and nanoporous silica (SAMMS) of similar surface chemistries in river water, groundwater, seawater, and human blood and plasma. DMSA-Fe3O4 had a capacity of 227 mg of Hg/g, a 30-fold larger value than GT-73. The nanoparticles removed 99 wt% of 1 mg/L Pb within a minute, while it took over 10 and 120 min for Chelex-100 and GT-73 to remove 96% of Pb.

Tailoring density and optical and thermal behavior of gold surfaces and nanoparticles exploiting aromatic dithiols.

PubMed

Bruno, Giovanni; Babudri, Francesco; Operamolla, Alessandra; Bianco, Giuseppe V; Losurdo, Maria; Giangregorio, Maria M; Hassan Omar, Omar; Mavelli, Fabio; Farinola, Gianluca M; Capezzuto, Pio; Naso, Francesco

2010-06-01

Self-assembled monolayers (SAMs) derived of 4-methoxy-terphenyl-3'',5''-dimethanethiol (TPDMT) and 4-methoxyterphenyl-4''-methanethiol (TPMT) have been prepared by chemisorption from solution onto gold thin films and nanoparticles. The SAMs have been characterized by spectroscopic ellipsometry, Raman spectroscopy and atomic force microscopy to determine their optical properties, namely the refractive index and extinction coefficient, in an extended spectral range of 0.75-6.5 eV. From the analysis of the optical data, information on SAMs structural organization has been inferred. Comparison of SAMs generated from the above aromatic thiols to well-known SAMs generated from the alkanethiol dodecanethiol revealed that the former aromatic SAMs are densely packed and highly vertically oriented, with a slightly higher packing density and a absence of molecular inclination in TPMT/Au. The thermal behavior of SAMs has also been monitored using ellipsometry in the temperature range 25-500 degrees C. Gold nanoparticles functionalized by the same aromatic thiols have also been discussed for surface enhanced Raman spectroscopy applications. This study represents a step forward tailoring the optical and thermal behavior of surfaces as well as nanoparticles.

Preparation of an Arg-Glu-Asp-Val Peptide Density Gradient on Hyaluronic Acid-Coated Poly(ε-caprolactone) Film and Its Influence on the Selective Adhesion and Directional Migration of Endothelial Cells.

PubMed

Yu, Shan; Gao, Ying; Mei, Xu; Ren, Tanchen; Liang, Su; Mao, Zhengwei; Gao, Changyou

2016-11-02

Selective adhesion and migration of endothelial cells (ECs) over smooth muscle cells (SMCs) is very important in the rapid endothelialization of blood-contacting implants to prevent vascular restenosis. In this study, a uniform cell-resistant layer of methacrylate-functionalized hyaluronic acid (HA) was first immobilized on a poly(ε-caprolactone) (PCL) film via polydopamine coupling. Then, a density gradient of thiol-functionalized Arg-Glu-Asp-Val (REDV) peptide was prepared on the HA layer via thiol-ene click chemistry and the continuous injection method. The REDV gradient selectively enhanced EC adhesion and preferential directional migration toward the region of higher REDV density, reaching 86% directionality in the middle of the gradient. The migration rate of ECs was also significantly enhanced twofold compared with that on tissue culture polystyrene (TCPS). In contrast, the gradient significantly weakened the adhesion of SMCs to 25% of that on TCPS but had no obvious impact on the migration rate and directionality. Successful modulation of the selective adhesion and directional migration of ECs over SMCs on biodegradable polymers serves as an important step toward practical applications for guided tissue regeneration.

Cloning of a Recombinant Plasmid Encoding Thiol-Specific Antioxidant Antigen (TSA) Gene of Leishmania majorand Expression in the Chinese Hamster Ovary Cell Line.

PubMed

Fatemeh, Ghaffarifar; Fatemeh, Tabatabaie; Zohreh, Sharifi; Abdolhosein, Dalimiasl; Mohammad Zahir, Hassan; Mehdi, Mahdavi

2012-01-01

TSA (thiol-specific antioxidant antigen) is the immune-dominant antigen of Leishmania major and is considered to be the most promising candidate molecule for a recombinant or DNA vaccine against leishmaniasis. The aim of the present work was to express a plasmid containing the TSA gene in eukaryotic cells. Genomic DNA was extracted, and the TSA gene was amplified by polymerase chain reaction (PCR). The PCR product was cloned into the pTZ57R/T vector, followed by subcloning into the eukaryotic expression vector pcDNA3 (EcoRI and HindIII sites). The recombinant plasmid was characterised by restriction digest and PCR. Eukaryotic Chinese hamster ovary cells were transfected with the plasmid containing the TSA gene. Expression of the L. major TSA gene was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting. The plasmid containing the TSA gene was successfully expressed, as demonstrated by a band of 22.1 kDa on Western blots. The plasmid containing the TSA gene can be expressed in a eukaryotic cell line. Thus, the recombinant plasmid may potentially be used as a DNA vaccine in animal models.

Hydrogen sulfide deactivates common nitrobenzofurazan-based fluorescent thiol labeling reagents.

PubMed

Montoya, Leticia A; Pluth, Michael D

2014-06-17

Sulfhydryl-containing compounds, including thiols and hydrogen sulfide (H2S), play important but differential roles in biological structure and function. One major challenge in separating the biological roles of thiols and H2S is developing tools to effectively separate the reactivity of these sulfhydryl-containing compounds. To address this challenge, we report the differential responses of common electrophilic fluorescent thiol labeling reagents, including nitrobenzofurazan-based scaffolds, maleimides, alkylating agents, and electrophilic aldehydes, toward cysteine and H2S. Although H2S reacted with all of the investigated scaffolds, the photophysical response to each scaffold was significantly different. Maleimide-based, alkylating, and aldehydic thiol labeling reagents provided a diminished fluorescence response when treated with H2S. By contrast, nitrobenzofurazan-based labeling reagents were deactivated by H2S addition. Furthermore, the addition of H2S to thiol-activated nitrobenzofurazan-based reagents reduced the fluorescence signal, thus establishing the incompatibility of nitrobenzofurazan-based thiol labeling reagents in the presence of H2S. Taken together, these studies highlight the differential reactivity of thiols and H2S toward common thiol-labeling reagents and suggest that sufficient care must be taken when labeling or measuring thiols in cellular environments that produce H2S due to the potential for both false-positive and eroded responses.

NADH oxidase activity (NOX) and enlargement of HeLa cells oscillate with two different temperature-compensated period lengths of 22 and 24 minutes corresponding to different NOX forms

NASA Technical Reports Server (NTRS)

Wang, S.; Pogue, R.; Morre, D. M.; Morre, D. J.

2001-01-01

NOX proteins are cell surface-associated and growth-related hydroquinone (NADH) oxidases with protein disulfide-thiol interchange activity. A defining characteristic of NOX proteins is that the two enzymatic activities alternate to generate a regular period length of about 24 min. HeLa cells exhibit at least two forms of NOX. One is tumor-associated (tNOX) and is inhibited by putative quinone site inhibitors (e.g., capsaicin or the antitumor sulfonylurea, LY181984). Another is constitutive (CNOX) and refractory to inhibition. The periodic alternation of activities and drug sensitivity of the NADH oxidase activity observed with intact HeLa cells was retained in isolated plasma membranes and with the solubilized and partially purified enzyme. At least two activities were present. One had a period length of 24 min and the other had a period length of 22 min. The lengths of both the 22 and the 24 min periods were temperature compensated (approximately the same when measured at 17, 27 or 37 degrees C) whereas the rate of NADH oxidation approximately doubled with each 10 degrees C rise in temperature. The rate of increase in cell area of HeLa cells when measured by video-enhanced light microscopy also exhibited a complex period of oscillations reflective of both 22 and 24 min period lengths. The findings demonstrate the presence of a novel oscillating NOX activity at the surface of cancer cells with a period length of 22 min in addition to the constitutive NOX of non-cancer cells and tissues with a period length of 24 min.

Engineering surfaces for bioconjugation: developing strategies and quantifying the extent of the reactions.

PubMed

Gauvreau, Virginie; Chevallier, Pascale; Vallières, Karine; Petitclerc, Eric; Gaudreault, René C; Laroche, Gaétan

2004-01-01

This study presents two-step and multistep reactions for modifying the surface of plasma-functionalized poly(tetrafluoroethylene) (PTFE) surfaces for subsequent conjugation of biologically relevant molecules. First, PTFE films were treated by a radiofrequency glow discharge (RFGD) ammonia plasma to introduce amino groups on the fluoropolymer surface. This plasma treatment is well optimized and allows the incorporation of a relative surface concentration of approximately 2-3.5% of amino groups, as assessed by chemical derivatization followed by X-ray photoelectron spectroscopy (XPS). In a second step, these amino groups were further reacted with various chemical reagents to provide the surface with chemical functionalities such as maleimides, carboxylic acids, acetals, aldehydes, and thiols, that could be used later on to conjugate a wide variety of biologically relevant molecules such as proteins, DNA, drugs, etc. In the present study, glutaric and cis-aconitic anhydrides were evaluated for their capability to provide carboxylic functions to the PTFE plasma-treated surface. Bromoacetaldehyde diethylacetal was reacted with the aminated PTFE surface, providing a diethylacetal function, which is a latent form of aldehyde functionality. Reactions with cross-linkers such as sulfo-succinimidyl derivatives (sulfo-SMCC, sulfo-SMPB) were evaluated to provide a highly reactive maleimide function suitable for further chemical reactions with thiolated molecules. Traut reagent (2-iminothiolane) was also conjugated to introduce a thiol group onto the fluoropolymer surface. PTFE-modified surfaces were analyzed by XPS with a particular attention to quantify the extent of the reactions that occurred on the polymer. Finally, surface immobilization of fibronectin performed using either glutaric anhydride or sulfo-SMPB activators demonstrated the importance of selecting the appropriate conjugation strategy to retain the protein biological activity.

2-Sulfonylpyrimidines: Mild alkylating agents with anticancer activity toward p53-compromised cells.

PubMed

Bauer, Matthias R; Joerger, Andreas C; Fersht, Alan R

2016-09-06

The tumor suppressor p53 has the most frequently mutated gene in human cancers. Many of p53's oncogenic mutants are just destabilized and rapidly aggregate, and are targets for stabilization by drugs. We found certain 2-sulfonylpyrimidines, including one named PK11007, to be mild thiol alkylators with anticancer activity in several cell lines, especially those with mutationally compromised p53. PK11007 acted by two routes: p53 dependent and p53 independent. PK11007 stabilized p53 in vitro via selective alkylation of two surface-exposed cysteines without compromising its DNA binding activity. Unstable p53 was reactivated by PK11007 in some cancer cell lines, leading to up-regulation of p53 target genes such as p21 and PUMA. More generally, there was cell death that was independent of p53 but dependent on glutathione depletion and associated with highly elevated levels of reactive oxygen species and induction of endoplasmic reticulum (ER) stress, as also found for the anticancer agent PRIMA-1(MET)(APR-246). PK11007 may be a lead for anticancer drugs that target cells with nonfunctional p53 or impaired reactive oxygen species (ROS) detoxification in a wide variety of mutant p53 cells.

Thiol-ene Michael-type formation of gelatin/poly(ethylene glycol) biomatrices for three-dimensional mesenchymal stromal/stem cell administration to cutaneous wounds

PubMed Central

Xu, Kedi; Cantu, David Antonio; Fu, Yao; Kim, Jaehyup; Zheng, Xiaoxiang; Hematti, Peiman; Kao, W. John

2013-01-01

Mesenchymal stromal/stem cells (MSCs) are considered promising cellular therapeutics in the fields of tissue engineering and regenerative medicine. MSCs secrete high concentrations of immunomodulatory cytokines and growth factors, which exert paracrine effects on infiltrating immune and resident cells of the wound microenvironment that could favorably promote healing after acute injury. However, better spatial delivery and improved retention at the site of injury are two factors that could improve the clinical application of MSCs. In this study, we utilized thiol-ene Michael-type addition for rapid encapsulation of MSCs within a gelatin/poly(ethylene glycol) biomatrix; this biomatrix was also applied as a provisional dressing to full-thickness wounds in Sprague-Dawley rats. The three-way interaction of MSCs, gelatin/poly(ethylene glycol) biomatrices, and host immune cells and adjacent resident cells of the wound microenvironment favorably modulated wound progression and host response. In this model we observed attenuated immune cell infiltration, lack of foreign giant cell (FBGC) formation, accelerated wound closure and re-epithelialization, as well as enhanced neovascularization and granulation tissue formation by 7 days. The MSC-entrapped gelatin/poly(ethylene glycol) biomatrix localized the presentation of MSCs adjacent to the wound microenvironment and thus, mediated early resolution of inflammatory events and facilitated proliferative phases in wound healing. PMID:23811217

Comparative study of the anti-HIV activities of ascorbate and thiol-containing reducing agents in chronically HIV-infected cells.

PubMed

Harakeh, S; Jariwalla, R J

1991-12-01

To elucidate the action of vitamin C on pathogenic human retroviruses, we investigated and compared the effects of noncytoxic concentrations of ascorbic acid (AA), its calcium salt (Ca-ascorbate), and two thiol-based reducing agents [glutathione (GSH) and N-acetyl-L-cysteine (NAC)] against human immunodeficiency virus (HIV)-1 replication in chronically infected T lymphocytes. Ca-ascorbate reduced extracellular HIV reverse transcriptase (RT) activity by about the same magnitude as the equivalent dose of AA. Long-term experiments showed that continuous presence of ascorbate was necessary for HIV suppression. NAC (10 mmol/L) caused less than twofold inhibition of HIV RT and conferred a synergistic effect (approximately eightfold inhibition) when tested simultaneously with AA (0.426 mmol/L). In contrast, nonesterified GSH (less than or equal to 1.838 mmol/L) had no effect on RT concentrations and did not potentiate the anti-HIV effect of AA. These results further support the potent antiviral activity of ascorbate and suggest its therapeutic value in controlling HIV infection in combination with thiols.

The evolution of glutathione metabolism in phototrophic microorganisms

NASA Technical Reports Server (NTRS)

Fahey, Robert C.; Buschbacher, Ralph M.; Newton, Gerald L.

1988-01-01

The low molecular weight thiol composition of a variety of phototropic microorganisms is examined in order to ascertain how evolution of glutathione (GSH) production is related to the evolution of oxygenic photosynthesis. Cells were extracted in the presence of monobromobimane (mBBr) to convert thiols (RSH) to fluorescent derivatives (RSmB) which were analyzed by high performance liquid chromatography (HPLC). Significant levels of GSH were not found in green sulfur bacteria. Substantial levels were present in purple bacteria, cyanobacteria, and eukaryotic algae. Other thiols measured included cysteine, gamma-glutamylcysteine, thiosulfate, coenzyme A, and sulfide. Many of the organisms also exhibited a marked ability to reduce mBBr to syn-(methyl,methyl)bimane, an ability which was quenched by treatment with 2-pyridyl disulfide or 5,5 prime-bisdithio - (2-nitrobenzoic acid) prior to reaction with mBBr. These observations indicate the presence of a reducing system capable of electron transfer to mBBr and reduction of reactive disulfides. The distribution of GSH in phototropic eubacteria indicates that GSH synthesis evolved at or around the time that oxygenic photosynthesis evolved.

Electrochemical Oxidation of l-selenomethionine and Se-methylseleno-l-cysteine at a Thiol-Compound-Modified Gold Electrode: Its Application in a Flow-Through Voltammetric Sensor.

PubMed

Wang, Lai-Hao; Zhang, Yu-Han

2017-02-16

A flow-electrolytic cell that consists of a bare gold wire or of different thiol-compound-modified gold electrodes (such as 2,4-thiazolidinedione, 2-mercapto-5-thiazoline, 2-mercaptothiazoline, l-cysteine, thioglycolic acid) was designed to be used in a voltammetric detector to identify l-selenomethionine and Se-methylseleno-l-cysteine using high-performance liquid chromatography. Both l-selenomethionine and Se-methylseleno-l-cysteine are more efficiently electrochemically oxidized on a thiol/gold than on a bare gold electrode. For the DC mode, and for measurements with suitable experimental parameters, a linear concentration from 10 to 1600 ng·mL -1 was found. The limits of quantification for l-selenomethionine and Se-methylseleno-l-cysteine were below 10 ng·mL -1 . The method can be applied to the quantitative determination of l-selenomethionine and Se-methylseleno-l-cysteine in commercial selenium-containing supplement products. Findings using high-performance liquid chromatography with a flow-through voltammetric detector and ultraviolet detector are comparable.

Crosslinking Protein Glutathionylation Mediated by O2-Arylated Bis-Diazeniumdiolate “Double JS-K”

PubMed Central

Holland, Ryan J.; Maciag, Anna E.; Kumar, Varun; Shi, Lei; Saavedra, Joseph E.; Prud’homme, Robert K.; Chakrapani, Harinath; Keefer, Larry K.

2012-01-01

Attachment of glutathione (GSH) to cysteine residues in proteins (S-glutathionylation) is a reversible post-translational modification that can profoundly alter protein structure and function. Often serving in a protective role, e.g., by temporarily saving protein thiols from irreversible oxidation and inactivation, glutathionylation can be identified and semi-quantitatively assessed using anti-GSH antibodies, thought to be specific for recognition of the S-glutathionylation modification. Here we describe an alternate mechanism of protein glutathionylation in which the sulfur atoms of the GSH and the protein’s thiol group are covalently bound via a crosslinking agent, rather than through a disulfide bond. This form of thiol crosslinking has been shown to occur and confirmed by mass spectrometry at the solution chemistry level, as well as in experiments documenting the potent antiproliferative activity of the bis-diazeniumdiolate Double JS-K in H1703 cells in vitro and in vivo. The modification is recognized by the anti-GSH antibody as if it were authentic S-glutathionylation, requiring mass spectrometry to distinguish between them. PMID:23106594

Synthesis and functionalization of coiled carbon filaments

NASA Astrophysics Data System (ADS)

Hikita, Muneaki

Coiled carbon filaments have one of the most attractive three-dimensional forms in carbon materials due to their helical morphologies. Because of their shape and carbon structure, they exhibit excellent mechanical and electrical properties such as superelasticity, low Young's modulus, relatively high electrical conductivity, and good electromagnetic (EM) wave absorption. Therefore, they are good candidates as fillers in composite materials for tactile sensor and electromagnetic interference shielding. In medical areas of interests, coiled carbon filaments can be used as micro and nano heaters or trigger for thermotherapy and biosensors using EM wave exposure because absorbed EM waves by coiled carbon filaments are converted into heat. Although various shapes of coiled carbon filaments have been discovered, optimum synthesis conditions and growth mechanisms of coiled carbon filaments are poorly understood. The study of growth kinetics is significant not only to analyze catalyst activity but also to establish the growth mechanisms of coiled carbon filaments. The establishment of growth mechanisms would be useful for determining optimum synthesis conditions and maximizing the quantity of carbon filaments synthesized for a given application. In the first study, tip grown single helical carbon filaments or carbon nanocoils (CNCs) were synthesized by a chemical vapor deposition method using tin-iron-oxide (Sn-Fe-O) xerogel film catalyst. The Sn-Fe-O catalyst was prepared by a low-cost sol-gel method using stannous acetate and ferric acetate as precursors. The growth kinetics of CNCs were monitored by a thermogravimetric analyzer, and the experimental result was correlated using a one-dimensional kinetic model, corresponding to one-dimensional tip growth. In the second study, bidirectionally grown double helical filaments or carbon microcoils (CMCs) were synthesized using a chemical vapor deposition method. CMCs obtained at two reaction temperatures were compared. CMCs grown at the higher temperature had smaller fiber size and coil diameter, and longer lifetime of catalyst. For in-depth analysis, growth kinetics of CMCs were studied using an exponential decay model for catalyst poisoning. In the third study, CMCs were functionalized for improvement of water dispersion, optical properties and self-assembly. As-grown CMCs were hydrophobic. To improve water dispersion for biological applications, the surface of as-grown CMCs were oxidized by concentrated nitric acid at room temperature. After the oxidation, the acid-treated CMCs were well dispersed in water. For optical property, CMCs were functionalized with octadecylamine (ODA). Upon photoexcitation, the functionalized CMCs exhibited photoluminescence in the visible region. Similar to carbon based nanoparticles, the photoluminescence of CMCs was attributed to electron-hole radiative recombination after surface passivation. The results suggest that these functionalized CMCs might be used as a new class of optical agents for biological applications. As a primary experiment to study Au-S bonding, aminoethanethiol (HSCH2CH2NH2) was attached to the surface of gold-coated CMCs. Energy dispersive X-ray (EDX) mapping shows gold, sulfur and nitrogen on the surface of CMCs. Then, a thiol-modified ssDNA attachment experiment was performed using a similar functionalization procedure as aminoethanethiol. The existence of phosphorus, nitrogen, oxygen and sulfur on surface of Au-coated CMCs immersed in thiol-modified ssDNA solution was confirmed by the EDX spectrum. The result indicates that ssDNA was fixed on their surface. In the fourth study, the effect of oxidized CMCs on mouse embryonic stem (MES) cells was examined to determine their toxicity. Mouse embryonic stem cells represent a unique cell population with the ability to undergo both self-renewal and differentiation. Results indicate that oxidized CMCs had very little toxicity on stem cell viability. There was no observed loss of alkaline phosphatase (AP) as a stem cell marker and mitochondrial membrane potential (MMP) of oxidized CMC-treated MES cells was unaffected. Oxidized CMCs did not show toxicity to MES cells at the cellular level.

Adsorption of Dissolved Metals in the Berkeley Pit using Thiol-Functionalized Self-Assembled Monolayers on Mesoporous Supports (Thiol-SAMMS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Betancourt, Amaury P.; Mattigod, Shas V.; Wellman, Dawn M.

2010-03-07

The Berkeley Pit in Butte, Montana, is heavily contaminated with dissolved metals. Adsorption and extraction of these metals can be accomplished through the use of a selective adsorbent. For this research, the adsorbent used was thiol-functionalized Self-Assembled Monolayers on Mesoporous Supports (thiol-SAMMS), which was developed at Pacific Northwest National Laboratory (PNNL). Thiol-SAMMS selectively binds to numerous types of dissolved metals. The objective of this research was to evaluate the loading and kinetics of aluminum, beryllium, copper, and zinc on thiol-SAMMS. For the loading tests, a series of Berkeley Pit water to thiol-SAMMS ratios (mL:g) were tested. These ratios were 1000:1,more » 500:1, 100:1, and 50:1. Berkeley Pit water is acidic (pH {approx} 2.5). This can affect the performance of SAMMS materials. Therefore, the effect of pH was evaluated by conducting parallel series of loading tests wherein the Berkeley Pit water was neutralized before or after addition of thiol-SAMMS, and a series of kinetics tests wherein the Berkeley Pit water was neutralized before addition of thiol-SAMMS for the first test and was not neutralized for the second test. For the kinetics tests, one Berkeley Pit water to thiol-SAMMS ratio was tested, which was 2000:1. The results of the loading and kinetics tests suggest that a significant decrease in dissolved metal concentration at Berkeley Pit could be realized through neutralization of Berkeley Pit water. Thiol-SAMMS technology has a limited application under the highly acidic conditions posed by the Berkeley Pit. However, thiol-SAMMS could provide a secondary remedial technique which would complete the remedial system and remove dissolved metals from the Berkeley Pit to below drinking water standards.« less

Evaluation of dynamic thiol/disulphide homeostasis as a novel indicator of oxidative stress in maple syrup urine disease patients under treatment.

PubMed

Zubarioglu, Tanyel; Kiykim, Ertugrul; Cansever, Mehmet Serif; Neselioglu, Salim; Aktuglu-Zeybek, Cigdem; Erel, Ozcan

2017-02-01

Maple syrup urine disease (MSUD) is a metabolic disorder that is caused by deficiency of branched-chain α-keto acid dehydrogenase complex. Although accumulation of toxic metabolites is associated with neurotoxicity, mechanisms underlying brain damage remain unclear. Aim of this study is to evaluate thiol/disulphide homeostasis as a novel indicator of oxidative stress in MSUD patients under treatment. Twenty patients with MSUD and 20 healthy individuals were included in study. All patients were under regular follow-up and had a good metabolic control. Serum native thiol (-SH), total thiol (-SH + -S-S-), disulphide (-S-S) levels were measured in all subjects. Disulphide/native thiol, disulphide/total thiol and native thiol/total thiol ratios were calculated from these values. Simultaneous blood sampling for plasma quantitative amino acid analysis was performed in both groups. Any significant difference was not observed in -SH, -SH + -S-S-, -S-S levels between two groups. In addition no increase of disulphide/native thiol and disulphide/total thiol ratios was detected in patient group. This study is the first study that evaluates dynamic thiol/disulphide homeostasis as an indicator of oxidative stress in MSUD patients. Among previous studies that were made to determine oxidative stress in treated MSUD patients, this study had the largest sample size also. In recent studies, it was claimed that oxidative stress could be responsible from neurotoxicity even in treated patients. Here, dynamic thiol/disulfide homeostasis status showed that providing good metabolic control in MSUD patients prevent oxidative stress. Under regular follow-up and good compliance with diet, additional antioxidant therapies would possibly not be necessary.

3D cell entrapment in crosslinked thiolated gelatin-poly(ethylene glycol) diacrylate hydrogels

PubMed Central

Fu, Yao; Xu, Kedi; Zheng, Xiaoxiang; Giacomin, A. Jeffrey; Mix, Adam W.; Kao, Weiyuan John

2012-01-01

The combined use of natural ECM components and synthetic materials offers an attractive alternative to fabricate hydrogel-based tissue engineering scaffolds to study cell-matrix interactions in three-dimensions (3D). A facile method was developed to modify gelatin with cysteine via a bifunctional PEG linker, thus introducing free thiol groups to gelatin chains. A covalently crosslinked gelatin hydrogel was fabricated using thiolated gelatin and poly(ethylene glycol) diacrylate (PEGdA) via thiol-ene reaction. Unmodified gelatin was physically incorporated in a PEGdA-only matrix for comparison. We sought to understand the effect of crosslinking modality on hydrogel physicochemical properties and the impact on 3D cell entrapment. Compared to physically incorporated gelatin hydrogels, covalently crosslinked gelatin hydrogels displayed higher maximum weight swelling ratio (Qmax), higher water content, significantly lower cumulative gelatin dissolution up to 7 days, and lower gel stiffness. Furthermore, fibroblasts encapsulated within covalently crosslinked gelatin hydrogels showed extensive cytoplasmic spreading and the formation of cellular networks over 28 days. In contrast, fibroblasts encapsulated in the physically incorporated gelatin hydrogels remained spheroidal. Hence, crosslinking ECM protein with synthetic matrix creates a stable scaffold with tunable mechanical properties and with long-term cell anchorage points, thus supporting cell attachment and growth in the 3D environment. PMID:21955690

Surface modification of poly(dimethylsiloxane) for microfluidic assay applications

NASA Astrophysics Data System (ADS)

Séguin, Christine; McLachlan, Jessica M.; Norton, Peter R.; Lagugné-Labarthet, François

2010-02-01

The surface of a poly(dimethylsiloxane) (PDMS) film was imparted with patterned functionalities at the micron-scale level. Arrays of circles with diameters of 180 and 230 μm were functionalized using plasma oxidation coupled with aluminum deposition, followed by silanization with solutions of 3-aminopropyltrimethoxy silane (3-APTMS) and 3-mercaptopropyltrimethoxy silane (3-MPTMS), to obtain patterned amine and thiol functionalities, respectively. The modification of the samples was confirmed using X-ray photoelectron spectroscopy (XPS), gold nanoparticle adhesion coupled with optical microscopy, as well as by derivatization with fluorescent dyes. To further exploit the novel surface chemistry of the modified PDMS, samples with surface amine functionalities were used to develop a protein assay as well as an array capable of cellular capture and patterning. The modified substrate was shown to successfully selectively immobilize fluorescently labeled immunoglobulin G (IgG) by tethering Protein A to the surface, and, for the cellular arrays, C2C12 rat endothelial cells were captured. Finally, this novel method of patterning chemical functionalities onto PDMS has been incorporated into microfluidic channels. Finally, we demonstrate the in situ chemical modification of the protected PDMS oxidized surface within a microfluidic device. This emphasizes the potential of our method for applications involving micron-scale assays since the aluminum protective layer permits to functionalize the oxidized PDMS surface several weeks after plasma treatment simply after etching away the metallic thin film.

Structural Basis of a Thiol-Disulfide Oxidoreductase in the Hedgehog-Forming Actinobacterium Corynebacterium matruchotii.

PubMed

Luong, Truc Thanh; Tirgar, Reyhaneh; Reardon-Robinson, Melissa E; Joachimiak, Andrzej; Osipiuk, Jerzy; Ton-That, Hung

2018-05-01

The actinobacterium Corynebacterium matruchotii has been implicated in nucleation of oral microbial consortia leading to biofilm formation. Due to the lack of genetic tools, little is known about basic cellular processes, including protein secretion and folding, in this organism. We report here a survey of the C. matruchotii genome, which encodes a large number of exported proteins containing paired cysteine residues, and identified an oxidoreductase that is highly homologous to the Corynebacterium diphtheriae thiol-disulfide oxidoreductase MdbA (MdbA Cd ). Crystallization studies uncovered that the 1.2-Å resolution structure of C. matruchotii MdbA (MdbA Cm ) possesses two conserved features found in actinobacterial MdbA enzymes, a thioredoxin-like fold and an extended α-helical domain. By reconstituting the disulfide bond-forming machine in vitro , we demonstrated that MdbA Cm catalyzes disulfide bond formation within the actinobacterial pilin FimA. A new gene deletion method supported that mdbA is essential in C. matruchotii Remarkably, heterologous expression of MdbA Cm in the C. diphtheriae Δ mdbA mutant rescued its known defects in cell growth and morphology, toxin production, and pilus assembly, and this thiol-disulfide oxidoreductase activity required the catalytic motif CXXC. Altogether, the results suggest that MdbA Cm is a major thiol-disulfide oxidoreductase, which likely mediates posttranslocational protein folding in C. matruchotii by a mechanism that is conserved in Actinobacteria IMPORTANCE The actinobacterium Corynebacterium matruchotii has been implicated in the development of oral biofilms or dental plaque; however, little is known about the basic cellular processes in this organism. We report here a high-resolution structure of a C. matruchotii oxidoreductase that is highly homologous to the Corynebacterium diphtheriae thiol-disulfide oxidoreductase MdbA. By biochemical analysis, we demonstrated that C. matruchotii MdbA catalyzes disulfide bond formation in vitro Furthermore, a new gene deletion method revealed that deletion of mdbA is lethal in C. matruchotii Remarkably, C. matruchotii MdbA can replace C. diphtheriae MdbA to maintain normal cell growth and morphology, toxin production, and pilus assembly. Overall, our studies support the hypothesis that C. matruchotii utilizes MdbA as a major oxidoreductase to catalyze oxidative protein folding. Copyright © 2018 American Society for Microbiology.

Thiol/disulfide status regulates the activity of thiol-containing kinases related to energy homeostasis in rat kidney.

PubMed

Rech, Virginia C; Mezzomo, Nathana J; Athaydes, Genaro A; Feksa, Luciane R; Figueiredo, Vandré C; Kessler, Adriana; Franceschi, Itiane D DE; Wannmacher, Clovis M D

2018-01-01

Considering that thiol-containing enzymes like kinases are critical for several metabolic pathways and energy homeostasis, we investigated the effects of cystine dimethyl ester and/or cysteamine administration on kinases crucial for energy metabolism in the kidney of Wistar rats. Animals were injected twice a day with 1.6 µmol/g body weight cystine dimethyl ester and/or 0.26 µmol/g body weight cysteamine from the 16th to the 20th postpartum day and euthanized after 12 hours. Pyruvate kinase, adenylate kinase, creatine kinase activities and thiol/disulfide ratio were determined. Cystine dimethyl ester administration reduced thiol/disulfide ratio and inhibited the kinases activities. Cysteamine administration increased the thiol/disulfide ratio and co-administration with cystine dimethyl ester prevented the inhibition of the enzymes. Regression between the thiol/disulfide ratio, and the kinases activities were significant. These results suggest that redox status may regulate energy metabolism in the rat kidney. If thiol-containing enzymes inhibition and oxidative stress occur in patients with cystinosis, it is possible that lysosomal cystine depletion may not be the only beneficial effect of cysteamine administration, but also its antioxidant and thiol-protector effect.

The Role of Thiol/Disulphide Homeostasis in Anthracycline Associated Cardiac Toxicity.

PubMed

Topuz, Mustafa; Şen, Omer; Kaplan, Mehmet; Akkus, Oguz; Erel, Ozcan; Gur, Mustafa

2017-02-07

The aim of the present study was to evaluate whether the baseline thiol/disulfide state can predict the occurrence of anthracycline induced cardiac toxicity. A total of 186 cancer patients receiving anthracycline (doxorubicin)-based chemotherapy were enrolled. All patients underwent 2-dimensional (2D) speckle tracking echocardiography (STE) to determine their left ventricular ejection fraction (LVEF) and blood samples for measuring thiol forms were obtained before treatment and 4 weeks after completion of the chemotherapy. The mean dose of doxorubicin exposure was 255 ± 39.2 mg/m 2 . Baseline native thiol was found to be lower whereas baseline disulfide and the disulfide/total thiol ratio were found to be higher in patients who had a decrease in LVEF after anthracycline therapy. Also, the amount of decrease in LVEF was well correlated with the delta value of the thiol forms. Logistic regression analysis revealed that changes in BNP and global longitudinal strain (GLS), baseline level of native thiol, disulfide, and the disulfide/total thiol ratio were strong predictors for a decrease in LVEF.The thiol/disulfide pathway may be a factor for predicting chemotherapy-induced cardiac toxicity as one of the oxidative stress mechanisms.

Changes in Thiol-Disulfide Homeostasis of the Body to Surgical Trauma in Laparoscopic Cholecystectomy Patients.

PubMed

Polat, Murat; Ozcan, Onder; Sahan, Leyla; Üstündag-Budak, Yasemin; Alisik, Murat; Yilmaz, Nigar; Erel, Özcan

2016-12-01

We aimed to investigate the short-term effect of laparoscopic surgery on serum thiol-disulfide homeostasis levels as a marker of oxidant stress of surgical trauma in elective laparoscopic cholecystectomy patients. Venous blood samples were collected, and levels of native thiols, total thiols, and disulfides were determined with a novel automated assay. Total antioxidant capacity (measured as the ferric-reducing ability of plasma) and serum ischemia modified albumin, expressed as absorbance units assayed by the albumin cobalt binding test, were determined. The major findings of the present study were that native thiol (283 ± 45 versus 241 ± 61 μmol/L), total thiol (313 ± 49 versus 263 ± 67 μmol/L), and disulfide (14.9 ± 4.6 versus 11.0 ± 6.1 μmol/L) levels were decreased significantly during operation and although they increased, they did not return to preoperation levels 24 hours after laparoscopic surgery compared to the levels at baseline. Disulfide/native thiol and disulfide/total thiol levels did not change during laparoscopic surgery. The decrease in plasma level of native and total thiol groups suggests impairment of the antioxidant capacity of plasma; however, the delicate balance between the different redox forms of thiols was maintained during surgery.

Differential regulation of the slow and rapid components of guinea-pig cardiac delayed rectifier K+ channels by hypoxia

PubMed Central

Hool, Livia C

2004-01-01

The aim of this study was to examine the effects of acute hypoxia on the slow (IKs) and rapid (IKr) components of the native delayed rectifier K+ channel in the absence and presence of the β-adrenergic receptor agonist isoproterenol (isoprenaline; Iso) using the whole-cell configuration of the patch-clamp technique. Hypoxia reversibly inhibited basal IKs. The effect could be mimicked by exposing the cells to the thiol-specific reducing agent dithiothreitol (DTT) and attenuated upon exposure of cells to the membrane-impermeant thiol-specific oxidizing compound 5,5′-dithio-bis[2-nitrobenzoic acid] (DTNB). In the presence of hypoxia, the K0.5 for activation of IKs by Iso was significantly decreased from 18.3 to 1.9 nm. DTT mimicked the effect of hypoxia on the sensitivity of IKs to Iso while DTNB had no effect. Hypoxia increased the sensitivity of IKs to histamine and forskolin suggesting that the effect of hypoxia is not occurring at the β-adrenergic receptor. The increase in sensitivity of IKs to Iso could be attenuated with addition of PKCβ peptide to the pipette solution. While hypoxia and DTT inhibited basal IKs they were without effect on IKr. In addition, Iso did not appear to alter the magnitude of IKr in the absence or presence of hypoxia. These data suggest that hypoxia regulates native IKs through two distinct mechanisms: direct inhibition of basal IKs and an increase in sensitivity to Iso that occurs downstream from the β-adrenergic receptor. Both mechanisms appear to involve redox modification of thiol groups. In contrast native IKr does not appear to be regulated by Iso, hypoxia or redox state. PMID:14634203

Dinitrogenase-Driven Photobiological Hydrogen Production Combats Oxidative Stress in Cyanothece sp. Strain ATCC 51142

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadler, Natalie C.; Bernstein, Hans C.; Melnicki, Matthew R.

ABSTRACT Photobiologically synthesized hydrogen (H 2) gas is carbon neutral to produce and clean to combust, making it an ideal biofuel.Cyanothecesp. strain ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H 2production, a highly perplexing phenomenon because H 2evolving enzymes are O 2sensitive. We employed a system-levelin vivochemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity. We found that NifHDK responds to intracellular redox conditions and may act as an emergency electron valve tomore » prevent harmful reactive oxygen species formation in concert with other cell strategies for maintaining redox homeostasis. These results provide new insight into cellular redox dynamics useful for advancing photolytic bioenergy technology and reveal a new understanding for the biological function of NifHDK. IMPORTANCEHere, we demonstrate that high levels of hydrogen synthesis can be induced as a protection mechanism against oxidative stress via the dinitrogenase enzyme complex inCyanothecesp. strain ATCC 51142. This is a previously unknown feature of cyanobacterial dinitrogenase, and we anticipate that it may represent a strategy to exploit cyanobacteria for efficient and scalable hydrogen production. We utilized a chemoproteomic approach to capture thein situdynamics of reductant partitioning within the cell, revealing proteins and reactive thiols that may be involved in redox sensing and signaling. Additionally, this method is widely applicable across biological systems to achieve a greater understanding of how cells navigate their environment and how redox chemistry can be utilized to alter metabolism and achieve homeostasis.« less

Emerging Role of Protein-Protein Transnitrosylation in Cell Signaling Pathways

PubMed Central

2013-01-01

Abstract Significance: Protein S-nitrosylation, a covalent reaction of a nitric oxide (NO) group with a critical protein thiol (or more properly thiolate anion), mediates an important form of redox-related signaling as well as aberrant signaling in disease states. Recent Advances: A growing literature suggests that over 3000 proteins are S-nitrosylated in cell systems. Our laboratory and several others have demonstrated that protein S-nitrosylation can regulate protein function by directly inhibiting catalytically active cysteines, by reacting with allosteric sites, or via influencing protein-protein interaction. For example, S-nitrosylation of critical cysteine thiols in protein-disulfide isomerase and in parkin alters their activity, thus contributing to protein misfolding in Parkinson's disease. Critical Issues: However, the mechanism by which specific protein S-nitrosylation occurs in cell signaling pathways is less well investigated. Interestingly, the recent discovery of protein-protein transnitrosylation reactions (transfer of an NO group from one protein to another) has revealed a unique mechanism whereby NO can S-nitrosylate a particular set of protein thiols, and represents a major class of nitrosylating/denitrosylating enzymes in mammalian systems. In this review, we will discuss recent evidence for transnitrosylation reactions between (i) hemoglobin/anion exchanger 1, (ii) thioredoxin/caspase-3, (iii) X-linked inhibitor of apoptosis/caspase-3, (iv) GAPDH-HDAC2/SIRT1/DNA-PK, and (v) Cdk5/dynamin related protein 1 (Drp1). This review also discusses experimental techniques useful in characterizing protein-protein transnitrosylations. Future Directions: Elucidation of additional transnitrosylation cascades will further our understanding of the enzymes that catalyze nitrosation, thereby contributing to NO-mediated signaling pathways. Antioxid. Redox Signal. 18, 239–249. PMID:22657837

Intracellular proteolysis of pancreatic zymogens.

PubMed Central

Gorelick, F. S.; Modlin, I. M.; Leach, S. D.; Carangelo, R.; Katz, M.

1992-01-01

Activation of pancreatic digestive zymogens within the pancreatic acinar cell may be an early event in the development of pancreatitis. To detect such activation, an immunoblot assay has been developed that measures the relative amounts of inactive zymogens and their respective active enzyme forms. Using this assay, high doses of cholecystokinin or carbachol were found to stimulate the intracellular conversion of at least three zymogens (procarboxypeptidase A1, procarboxypeptidase B, and chymotrypsinogen 2) to their active forms. Thus, this conversion may be a generalized phenomenon of pancreatic zymogens. The conversion is detected within ten minutes of treatment and is not associated with changes in acinar cell morphology; it has been predicted that the lysosomal thiol protease, cathepsin B, may initiate this conversion. Small amounts of cathepsin B are found in the secretory pathway, and cathepsin B can activate trypsinogen in vitro; however, exposure of acini to a thiol protease inhibitor (E64) did not block this conversion. Conversion was inhibited by the serine protease inhibitor, benzamidine, and by raising the intracellular pH, using chloroquine or monensin. This limited proteolytic conversion appears to require a low pH compartment and a serine protease activity. After long periods of treatment (60 minutes), the amounts of the active enzyme forms began to decrease; this observation suggested that the active enzyme forms were being degraded. Treatment of acini with E64 reduced this late decrease in active enzyme forms, suggesting that thiol proteases, including lysosomal hydrolases, may be involved in the degradation of the active enzyme forms. These findings indicate that pathways for zymogen activation as well as degradation of active enzyme forms are present within the pancreatic acinar cell. Images FIG. 1 FIG. 6 PMID:1340058

A microfabricated platform with hydrogel arrays for 3D mechanical stimulation of cells.

PubMed

Liu, Haijiao; Usprech, Jenna; Sun, Yu; Simmons, Craig A

2016-04-01

Cellular microenvironments present cells with multiple stimuli, including not only soluble biochemical and insoluble matrix cues but also mechanical factors. Biomaterial array platforms have been used to combinatorially and efficiently probe and define two-dimensional (2D) and 3D microenvironmental cues to guide cell functions for tissue engineering applications. However, there are few examples of array platforms that include dynamic mechanical forces, particularly to enable stretching of 3D cell-seeded biomaterials, which is relevant to engineering connective and cardiovascular tissues. Here we present a deformable membrane platform that enables 3D dynamic mechanical stretch of arrayed biomaterial constructs. Cell-seeded polyethylene glycol norbornene (PEG-NB) hydrogels were bound to miniaturized deformable membranes via a thiol-ene reaction with off-stoichiometry thiol-ene based polydimethylsiloxane (OSTE-PDMS) as the membrane material. Bonding to OSTE-PDMS enabled the 3D hydrogel microconstructs to be cyclically deformed and stretched by the membrane. As a first demonstration, human mesenchymal stromal cells (MSCs) embedded in PEG-NB were stretched for several days. They were found to be viable, spread in the 3D hydrogels, and exhibited a contractile myofibroblast phenotype when exposed to dynamic 3D mechanical deformation. This platform, which is readily scalable to larger arrays, enables systematic interrogation of the relationships between combinations of 3D mechanobiological cues and cellular responses, and thus has the potential to identify strategies to predictably control the construction of functional engineered tissues. Current high-throughput biomaterial screening approaches fail to consider the effects of dynamic mechanical stimulation, despite its importance in a wide variety of regenerative medicine applications. To meet this need, we developed a deformable membrane platform that enables 3D dynamic stretch of arrayed biomaterial constructs. Our approach combines microtechnologies fabricated with off-stoichiometry thiol-ene based polydimethylsiloxane membranes that can covalently bond cell-seeded polyethylene glycol norbornene 3D hydrogels, a model biomaterial with tunable adhesive, elastic and degradation characteristics. As a first demonstration, we show that human mesenchymal stromal cells embedded in hydrogels and subjected to dynamic mechanical stimulation undergo myofibroblast differentiation. This system is readily scaled up to larger arrays, and will enable systematic and efficient screening of combinations of 3D mechanobiological and biomaterial cues on cell fate and function. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Assessment of the aroma impact of major odor-active thiols in pan-roasted white sesame seeds by calculation of odor activity values.

PubMed

Tamura, Hitoshi; Fujita, Akira; Steinhaus, Martin; Takahisa, Eisuke; Watanabe, Hiroyuki; Schieberle, Peter

2011-09-28

Eleven odor-active thiols, namely, 2-methyl-1-propene-1-thiol, (Z)-3-methyl-1-butene-1-thiol, (E)-3-methyl-1-butene-1-thiol, (Z)-2-methyl-1-butene-1-thiol, (E)-2-methyl-1-butene-1-thiol, 2-methyl-3-furanthiol, 3-mercapto-2-pentanone, 2-mercapto-3-pentanone, 4-mercapto-3-hexanone, 3-mercapto-3-methylbutyl formate, and 2-methyl-3-thiophenethiol, recently identified in an extract prepared from white sesame seeds, were quantitated in sesame using stable isotope dilution analyses. For that purpose, the following deuterium-labeled compounds were synthesized and used as internal standards in the quantitation assays: [2H6]-2-methyl-1-propene-1-thiol, [2H3]-(E)- and [2H3]-(Z)-2-methyl-1-butene-1-thiol, [2H3]-2-methyl-3-furanthiol, [2H2]-3-mercapto-2-pentanone, [2H3]-4-mercapto-3-hexanone, [2H6]-3-mercapto-3-methylbutyl formate, and [2H3]-2-methyl-3-thiophenethiol. On the basis of the results obtained, odor activity values (OAVs) were calculated as ratio of the concentration and odor threshold of the individual compounds in cooking oil. According to their high OAVs, particularly the 3-methyl-1-butene-1-thiols (OAV: 2400) and the 2-methyl-1-butene-1-thiols (OAV: 960) were identified as the most odor-active compounds in pan-roasted white sesame seeds. These compounds were therefore suggested to be mainly responsible for the characteristic but rather unstable sulfury aroma of freshly pan-roasted white sesame seeds.

Control of Gallium Oxide Growth on Liquid Metal Eutectic Gallium/Indium Nanoparticles via Thiolation.

PubMed

Farrell, Zachary J; Tabor, Christopher

2018-01-09

Eutectic gallium-indium alloy (EGaIn, a room-temperature liquid metal) nanoparticles are of interest for their unique potential uses in self-healing and flexible electronic devices. One reason for their interest is due to a passivating oxide skin that develops spontaneously on exposure to ambient atmosphere which resists deformation and rupture of the resultant liquid particles. It is then of interest to develop methods for control of this oxide growth process. It is hypothesized here that functionalization of EGaIn nanoparticles with thiolated molecules could moderate oxide growth based on insights from the Cabrera-Mott oxidation model. To test this, the oxidation dynamics of several thiolated nanoparticle systems were tracked over time with X-ray photoelectron spectroscopy. These results demonstrate the ability to suppress gallium oxide growth by up to 30%. The oxide progressively matures over a 28 day period, terminating in different final thicknesses as a function of thiol selection. These results indicate not only that thiols moderate gallium oxide growth via competition with oxygen for surface sites but also that different thiols alter the thermodynamics of oxide growth through modification of the EGaIn work function.

Cysteine-conjugated metabolite of ginger component [6]-shogaol serves as a carrier of [6]-shogaol in cancer cells and in mice

PubMed Central

Chen, Huadong; Soroka, Dominique N.; Zhu, Yingdong; Hu, Yuhui; Chen, Xiaoxin; Sang, Shengmin

2013-01-01

Shogaols, a series of major constituents in dried ginger (Zingiber officinale), show high anti-cancer potencies. Previously, we reported that a major metabolite resulting from the mercapturic acid pathway, 5-cysteinyl-[6]-shogaol (M2), showed comparable growth inhibitory effects towards cancer cells to [6]-shogaol (6S). Here we probe the mechanism by which M2 exerts its bioactivity. We utilized a series of chemical stability tests in conjunction with bioassays to show that thiol-conjugates display chemopreventative potency by acting as carriers of active ginger component 6S. M2 chemical degradation to 6S was observed in an environment most resembling physiological conditions, with a pH of 7.4 at 37°C. The metabolic profiles of M2 in cancer cells HCT-116 and H-1299 resembled those of 6S, indicating that its biotransformation route was initiated by deconjugation. Further, the presence of excess glutathione significantly delayed 6S and M2 metabolism and counteracted cell death induced by 6S and M2, suggesting that increasing available free thiols exogenously both promoted formation of 5-glutathionyl-[6]-shogaol (M13) and inhibited the production of free 6S from M2 deconjugation, resulting in delayed 6S cell entry and bioactivity. Given the chemopreventative properties of M2 and our observations in vitro, we investigated its metabolism in mice. M2 and 6S showed similar metabolic profiles in mouse urine and fecal samples. Six new thiol-conjugated metabolites (M16–M21), together with previously reported ones, were identified by LC/MS. In particular, the increase of 5-N-acetylcystenyl-[6]-shogaol (M5) and its 3′-demethylated product (M16) abundance in mouse feces after treatment with M2 indicate that in addition to acting as a carrier of 6S, M2 is also directly acetylated to M5, which is further demethylated to M16 in vivo. In conclusion, cysteine-conjugated metabolite of [6]-shogaol M2 exerts its bioactivity by acting as a carrier of 6S in both cancer cells and in mice. PMID:23638641

Cysteine-conjugated metabolite of ginger component [6]-shogaol serves as a carrier of [6]-shogaol in cancer cells and in mice.

PubMed

Chen, Huadong; Soroka, Dominique N; Zhu, Yingdong; Hu, Yuhui; Chen, Xiaoxin; Sang, Shengmin

2013-06-17

Shogaols, a series of major constituents in dried ginger (Zingiber officinale), show high anticancer potencies. Previously, we reported that a major metabolite resulting from the mercapturic acid pathway, 5-cysteinyl-[6]-shogaol (M2), showed comparable growth inhibitory effects toward cancer cells to [6]-shogaol (6S). Here, we probe the mechanism by which M2 exerts its bioactivity. We utilized a series of chemical stability tests in conjunction with bioassays to show that thiol-conjugates display chemopreventative potency by acting as carriers of active ginger component 6S. M2 chemical degradation to 6S was observed in an environment most resembling physiological conditions, with a pH of 7.4 at 37 °C. The metabolic profiles of M2 in cancer cells HCT-116 and H-1299 resembled those of 6S, indicating that its biotransformation route was initiated by deconjugation. Further, the presence of excess glutathione significantly delayed 6S and M2 metabolism and counteracted cell death induced by 6S and M2, suggesting that increasing available free thiols exogenously both promoted the formation of 5-glutathionyl-[6]-shogaol (M13) and inhibited the production of free 6S from M2 deconjugation, resulting in delayed 6S cell entry and bioactivity. Given the chemopreventative properties of M2 and our observations in vitro, we investigated its metabolism in mice. M2 and 6S showed similar metabolic profiles in mouse urine and fecal samples. Six new thiol-conjugated metabolites (M16-M21), together with previously reported ones, were identified by LC/MS. In particular, the increase of 5-N-acetylcystenyl-[6]-shogaol (M5) and its 3'-demethylated product (M16) abundance in mouse feces after treatment with M2 indicates that in addition to acting as a carrier of 6S, M2 is also directly acetylated to M5, which is further demethylated to M16 in vivo. In conclusion, the cysteine-conjugated metabolite of [6]-shogaol M2 exerts its bioactivity by acting as a carrier of 6S in both cancer cells and in mice.

Dissolved low-molecular weight thiol concentrations from the U.S. GEOTRACES North Atlantic Ocean zonal transect

NASA Astrophysics Data System (ADS)

Swarr, Gretchen J.; Kading, Tristan; Lamborg, Carl H.; Hammerschmidt, Chad R.; Bowman, Katlin L.

2016-10-01

Low-molecular weight thiols, including cysteine and glutathione, are biomolecules involved in a variety of metabolic pathways and act as important antioxidant and metal buffering agents. In this last capacity, they represent a potential mechanism for modulating the bioavailability and biogeochemistry of many trace elements in the ocean, particularly for chalcophilic elements (e.g., Cu, Zn, Cd, Ag and Hg). For this reason, and in the context of the international GEOTRACES program that seeks to understand the biogeochemistry of trace elements in the ocean, we measured the concentration of individual dissolved low-molecular weight thiols during the U.S. GEOTRACES North Atlantic Zonal Transect (USGNAZT). Only two thiols were identified, cysteine and glutathione, in contrast to results from the northeast subarctic Pacific Ocean, where the dipeptides glycine-cysteine and arginine-cysteine were also present and γ-glutamylcysteine was dominant. Concentrations of cysteine and glutathione in the North Atlantic Ocean were lower than in the Pacific and ranged from below detection ( 0.01 nM) to 0.61 nM of cysteine and up to 1.0 nM of glutathione, with cysteine generally more abundant than glutathione. Vertical profiles of cysteine and glutathione were broadly consistent with their biological production, being more abundant in surface water and usually below detection at depths greater than about 200 m. Subsurface concentration maxima, often co-incident with the deep chlorophyll maximum, were frequently observed but not universal. We conclude that cysteine and glutathione do not make up significant portions of complexation capacity for Cu and Zn in the upper open ocean but could be important for Cd, Hg, and potentially other chalcophiles. Extremely low concentrations of cysteine and glutathione in deep water suggest that higher molecular-weight thiols are a more important ligand class for chalcophiles in that portion of the ocean.

Effects of oxygen on biofilm formation and the AtlA autolysin of Streptococcus mutans.

PubMed

Ahn, Sang-Joon; Burne, Robert A

2007-09-01

The Streptococcus mutans atlA gene encodes an autolysin required for biofilm maturation and biogenesis of a normal cell surface. We found that the capacity to form biofilms by S. mutans, one of the principal causative agents of dental caries, was dramatically impaired by growth of the organism in an aerated environment and that cells exposed to oxygen displayed marked changes in surface protein profiles. Inactivation of the atlA gene alleviated repression of biofilm formation in the presence of oxygen. Also, the formation of long chains, a characteristic of AtlA-deficient strains, was less evident in cells grown with aeration. The SMu0629 gene is immediately upstream of atlA and encodes a product that contains a C-X-X-C motif, a characteristic of thiol-disulfide oxidoreductases. Inactivation of SMu0629 significantly reduced the levels of AtlA protein and led to resistance to autolysis. The SMu0629 mutant also displayed an enhanced capacity to form biofilms in the presence of oxygen compared to that of the parental strain. The expression of SMu0629 was shown to be under the control of the VicRK two-component system, which influences oxidative stress tolerance in S. mutans. Disruption of vicK also led to inhibition of processing of AtlA, and the mutant was hyperresistant to autolysis. When grown under aerobic conditions, the vicK mutant also showed significantly increased biofilm formation compared to strain UA159. This study illustrates the central role of AtlA and VicK in orchestrating growth on surfaces and envelope biogenesis in response to redox conditions.

Thioredoxin targets in plants: The first 30 years

USDA-ARS?s Scientific Manuscript database

The turn of the century welcomed major developments in redox biology. In one development with plants, proteomics made possible the identification of proteins linked to thioredoxin (Trx), initially in chloroplasts and then other cell compartments. Two procedures, one based on thiol specific probes an...

Determination and isolation of a thioesterase from passion fruit (Passiflora edulis Sims) that hydrolyzes volatile thioesters.

PubMed

Tapp, Edward J; Cummins, Ian; Brassington, David; Edwards, Robert

2008-08-13

Volatile organosulfur compounds (VOSCs) are high impact aroma chemicals characteristic of tropical fruits which are active as both free thiols and the respective thioesters. Using a simple and sensitive colorimetric enzyme assay, a thioesterase activity toward VOSCs has been identified in ripening purple passion fruit ( Passiflora edulis Sims). The assay was based on determining the release of free thiols from 2-methyl-3-furanthiol acetate using Ellman's reagent. The major thioesterase in the fruit was found to be a wall-bound protein in the mesocarp. The extracted enzyme activity was purified 150-fold and shown to be associated with a 43 kDa monomeric serine hydrolase which was selectively labeled with a fluorophosphonate suicide probe. MS-MS sequencing identified the thioesterase as a class 13 glycoside hydrolase, most similar to pectin acetylesterase, an enzyme involved in cell wall modifications in the peel of a number of fruit. Our results suggest that cell wall hydrolases in tropical fruit may have additional useful roles in biotransforming VOSCs.

Enzymatic reduction of disulfide bonds in lysosomes: Characterization of a Gamma-interferon-inducible lysosomal thiol reductase (GILT)

NASA Astrophysics Data System (ADS)

Arunachalam, Balasubramanian; Phan, Uyen T.; Geuze, Hans J.; Cresswell, Peter

2000-01-01

Proteins internalized into the endocytic pathway are usually degraded. Efficient proteolysis requires denaturation, induced by acidic conditions within lysosomes, and reduction of inter- and intrachain disulfide bonds. Cytosolic reduction is mediated enzymatically by thioredoxin, but the mechanism of lysosomal reduction is unknown. We describe here a lysosomal thiol reductase optimally active at low pH and capable of catalyzing disulfide bond reduction both in vivo and in vitro. The active site, determined by mutagenesis, consists of a pair of cysteine residues separated by two amino acids, similar to other enzymes of the thioredoxin family. The enzyme is a soluble glycoprotein that is synthesized as a precursor. After delivery into the endosomal/lysosomal system by the mannose 6-phosphate receptor, N- and C-terminal prosequences are removed. The enzyme is expressed constitutively in antigen-presenting cells and induced by IFN-γ in other cell types, suggesting a potentially important role in antigen processing.

Protein S-glutathionylation: from current basics to targeted modifications.

PubMed

Popov, Doina

2014-10-01

The interaction between antioxidant glutathione and the free thiol in susceptible cysteine residues of proteins leads to reversible protein S-glutathionylation. This reaction ensures cellular homeostasis control (as a common redox-dependent post-translational modification associated with signal transduction) and intervenes in oxidative stress-related cardiovascular pathology (as initiated by redox imbalance). The purpose of this review is to evaluate the recent knowledge on protein S-glutathionylation in terms of chemistry, broad cellular intervention, specific quantification, and potential for therapeutic exploitation. The data bases searched were Medline and PubMed, from 2009 to 2014 (term: glutathionylation). Protein S-glutathionylation ensures protection of protein thiols against irreversible over-oxidation, operates as a biological redox switch in both cell survival (influencing kinases and protein phosphatases pathways) and cell death (by potentiation of apoptosis), and cross-talks with phosphorylation and with S-nitrosylation. Collectively, protein S-glutathionylation appears as a valuable biomarker for oxidative stress, with potential for translation into novel therapeutic strategies.

Thiolated hyaluronan-based hydrogels crosslinked using oxidized glutathione: an injectable matrix designed for ophthalmic applications.

PubMed

Zarembinski, Thomas I; Doty, Nathaniel J; Erickson, Isaac E; Srinivas, Ramya; Wirostko, Barbara M; Tew, William P

2014-01-01

Future ophthalmic therapeutics will require the sustained delivery of bioactive proteins and nucleic acid-based macromolecules and/or provide a suitable microenvironment for the localization and sustenance of reparative progenitor cells after transplantation into or onto the eye. Water-rich hydrogels are ideal vehicles for such cargo, but few have all the qualities desired for novel ophthalmic use, namely in situ gelation speed, cytocompatibility, biocompatibility and capacity to functionalize. We describe here the development of an ophthalmic-compatible crosslinking system using oxidized glutathione (GSSG), a physiologically relevant molecule with a history of safe use in humans. When GSSG is used in conjunction with an existing hyaluronate-based, in situ crosslinkable hydrogel platform, gels form in less than 5 min using the thiol-disulfide exchange reaction. This GSSG hydrogel supports the 3-D culture of adipose-derived stem cells in vitro and shows biocompatibility in preliminary intracutaneous and subconjunctival experiments in vivo. In addition, the thiol-disulfide exchange reaction can also be used in conjunction with other thiol-compatible chemistries to covalently link peptides for more complex formulations. These data suggest that this hydrogel could be well suited for local ocular delivery, focusing initially on front of the eye therapies. Subsequent uses of the hydrogel include delivery of back of the eye treatments and eventually into other soft, hyaluronan-rich tissues such as those from the liver and brain. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Modulation of oxidative damage by nitroxide free radicals.

PubMed

Dragutan, Ileana; Mehlhorn, Rolf J

2007-03-01

Piperidine nitroxides like 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) are persistent free radicals in non-acidic aqueous solutions and organic solvents that may have value as therapeutic agents in medicine. In biological environments, they undergo mostly reduction to stable hydroxylamines but can also undergo oxidation to reactive oxoammonium compounds. Reactions of the oxoammonium derivatives could have adverse consequences including chemical modification of vital macromolecules and deleterious effects on cell signaling. An examination of their reactivity in aqueous solution has shown that oxoammonium compounds can oxidize almost any organic as well as many inorganic molecules found in biological systems. Many of these reactions appear to be one-electron transfers that reduce the oxoammonium to the corresponding nitroxide species, in contrast to a prevalence of two-electron reductions of oxoammonium in organic solvents. Amino acids, alcohols, aldehydes, phospholipids, hydrogen peroxide, other nitroxides, hydroxylamines, phenols and certain transition metal ions and their complexes are among reductants of oxoammonium, causing conversion of this species to the paramagnetic nitroxide. On the other hand, thiols and oxoammonium yield products that cannot be detected by ESR even under conditions that would oxidize hydroxylamines to nitroxides. These products may include hindered secondary amines, sulfoxamides and sulfonamides. Thiol oxidation products other than disulfides cannot be restored to thiols by common enzymatic reduction pathways. Such products may also play a role in cell signaling events related to oxidative stress. Adverse consequences of the reactions of oxoammonium compounds may partially offset the putative beneficial effects of nitroxides in some therapeutic settings.

Redox Modification of Cysteine Residues Regulates the Cytokine Activity of High Mobility Group Box-1 (HMGB1)

PubMed Central

Yang, Huan; Lundbäck, Peter; Ottosson, Lars; Erlandsson-Harris, Helena; Venereau, Emilie; Bianchi, Marco E; Al-Abed, Yousef; Andersson, Ulf; Tracey, Kevin J; Antoine, Daniel J

2012-01-01

High mobility group box 1 (HMGB1) is a nuclear protein with extracellular inflammatory cytokine activity. It is released passively during cell injury and necrosis, and secreted actively by immune cells. HMGB1 contains three conserved redox-sensitive cysteine residues: C23 and C45 can form an intramolecular disulfide bond, whereas C106 is unpaired and is essential for the interaction with Toll-Like Receptor (TLR) 4. However, a comprehensive characterization of the dynamic redox states of each cysteine residue and of their impacts on innate immune responses is lacking. Using tandem mass spectrometric analysis, we now have established that the C106 thiol and the C23–C45 disulfide bond are required for HMGB1 to induce nuclear NF-κB translocation and tumor necrosis factor (TNF) production in macrophages. Both irreversible oxidation to sulphonates and complete reduction to thiols of these cysteines inhibited TNF production markedly. In a proof of concept murine model of hepatic necrosis induced by acetaminophen, during inflammation, the predominant form of serum HMGB1 is the active one, containing a C106 thiol group and a disulfide bond between C23 and C45, whereas the inactive form of HMGB1, containing terminally oxidized cysteines, accumulates during inflammation resolution and hepatic regeneration. These results reveal critical posttranslational redox mechanisms that control the proinflammatory activity of HMGB1 and its inactivation during pathogenesis. PMID:22105604

Carvedilol: relation between antioxidant activity and inhibition of the mitochondrial permeability transition.

PubMed

Oliveira, Paulo J; Esteves, Telma; Rolo, Anabela P; Monteiro, Pedro; Gonçalves, Lino; Palmeira, Carlos M; Moreno, António J

2003-01-01

The mitochondrial permeability transition (MPT) is an event related to severe oxidative stress (for example, during myocardial ischemia and reperfusion) and excessive mitochondrial calcium accumulation, also being implicated in cell death. In this study, we compared the effect of carvedilol on the cardiac MPT induced by calcium and phosphate (Ca/Pi) and calcium/carboxyatractyloside (Ca/Catr). Oxidative stress plays a major role in MPT induction by Ca/Pi, leading to the oxidation of protein thiol groups, in contrast with Ca/Catr, where such oxidation is secondary to MPT induction and is not caused by oxidative stress. Mitochondria were isolated from rat hearts and parameters related to MPT induction were evaluated (n = 5 for each inducer): mitochondrial swelling and oxidation of protein thiol groups (both measured by spectrophotometry). Using Ca/Pi, carvedilol protected mitochondria from MPT induction, particularly in its high conductance form. Its effect was demonstrated by analyzing the decrease in mitochondrial swelling amplitude. Simultaneously, we observed inhibition of protein thiol group oxidation (p < 0.001). By contrast, carvedilol did not show any protective effect with Ca/Catr. Carvedilol was only effective against the MPT when the oxidation of protein thiol groups was the cause and not the consequence of the MPT phenomenon. The results clearly show that during myocardial aggressions (ischemia and reperfusion, for example), the protective effect of carvedilol is primarily due to an antioxidant mechanism, inhibiting the production and effects of reactive oxygen species.

Application of Atmospheric Pressure Photoionization H/D-exchange Mass Spectrometry for Speciation of Sulfur-containing Compounds.

PubMed

Acter, Thamina; Kim, Donghwi; Ahmed, Arif; Ha, Ji-Hyoung; Kim, Sunghwan

2017-08-01

Herein we report the observation of atmospheric pressure in-source hydrogen-deuterium exchange (HDX) of thiol group for the first time. The HDX for thiol group was optimized for positive atmospheric pressure photoionization (APPI) mass spectrometry (MS). The optimized HDX-MS was applied for 31 model compounds (thiols, thiophenes, and sulfides) to demonstrate that exchanged peaks were observed only for thiols. The optimized method has been successfully applied to the isolated fractions of sulfur-rich oil samples. The exchange of one and two thiol hydrogens with deuterium was observed in the thiol fraction; no HDX was observed in the other fractions. Thus, the results presented in this study demonstrate that the HDX-MS method using APPI ionization source can be effective for speciation of sulfur compounds. This method has the potential to be used to access corrosion problems caused by thiol-containing compounds. Graphical Abstract ᅟ.

Synthesis of a thiol-β-cyclodextrin, a potential agent for controlling enzymatic browning in fruits and vegetables.

PubMed

Manta, Carmen; Peralta-Altier, Gabriela; Gioia, Larissa; Méndez, María F; Seoane, Gustavo; Ovsejevi, Karen

2013-11-27

A thiol-β-cyclodextrin was synthesized by a simple and environmentally friendly three-step method comprising epoxy activation of β-cyclodextrin, thiosulfate-mediated oxirane opening, and further reduction of the S-alkyl thiosulfate to a thiol group. The final step was optimized by using thiopropyl-agarose, a solid phase reducing agent with many advantages over soluble ones. β-Cyclodextrin thiolation was confirmed by titration with a thiol-reactive reagent, NMR studies, and MALDI-TOF/TOF. Thiolated cyclodextrin had an average value of one thiol group per molecule. Thiol-β-cyclodextrin proved to be an excellent agent for controlling polyphenol oxidase activity. This copper-containing enzyme is responsible for browning in fruits and vegetables. Under the same conditions, thiol-β-cyclodextrin generated a reductive microenvironment that increased the antibrowning effect on Red Delicious apples compared to unmodified β-cyclodextrin.

The Expanding Landscape of the Thiol Redox Proteome*

PubMed Central

Yang, Jing; Carroll, Kate S.; Liebler, Daniel C.

2016-01-01

Cysteine occupies a unique place in protein chemistry. The nucleophilic thiol group allows cysteine to undergo a broad range of redox modifications beyond classical thiol-disulfide redox equilibria, including S-sulfenylation (-SOH), S-sulfinylation (-SO2H), S-sulfonylation (-SO3H), S-nitrosylation (-SNO), S-sulfhydration (-SSH), S-glutathionylation (-SSG), and others. Emerging evidence suggests that these post-translational modifications (PTM) are important in cellular redox regulation and protection against oxidative damage. Identification of protein targets of thiol redox modifications is crucial to understanding their roles in biology and disease. However, analysis of these highly labile and dynamic modifications poses challenges. Recent advances in the design of probes for thiol redox forms, together with innovative mass spectrometry based chemoproteomics methods make it possible to perform global, site-specific, and quantitative analyses of thiol redox modifications in complex proteomes. Here, we review chemical proteomic strategies used to expand the landscape of thiol redox modifications. PMID:26518762

Radioprotective Thiolamines WR-1065 and WR-33278 Selectively Denature Nonhistone Nuclear Proteins

NASA Technical Reports Server (NTRS)

Booth, Valerie K.; Roberts, Jeanette C.; Warters, Raymond L.; Wilmore, Britta H.; Lepock, James R.

2000-01-01

Differential scanning calorimetry was used to study the interactions of nuclei isolated from Chinese hamster V79 cells with the radioprotector WR-1065, other thiol compounds, and polyamines. Differential scanning calorimetry monitors denaturation of macromolecules and resolves the major nuclear components (e.g. constrained and relaxed DNA, nucleosome core, and nuclear matrix) of intact nuclei on the basis of thermal stability. WR-1065 treatment (0.5-10 mM) of isolated nuclei led to the irreversible denaturation of nuclear proteins, a fraction of which are nuclear matrix proteins. Denaturation of 50% of the total nonhistone nuclear protein content of isolated nuclei occurred after exposure to 4.7 mM WR-1065 for 20 min at 23 C. In addition, a 22% increase in the insoluble protein content of nuclei isolated from V79 cells that had been treated with 4 mM WR-1065 for 30 min at 37 C was observed, indicating that WR-1065-induced protein denaturation occurs not only in isolated nuclei but also in the nuclei of intact cells. From the extent of the increase in insoluble protein in the nucleus, protein denaturation by WR-1065 is expected to contribute to drug toxicity at concentrations greater than approximately 4 mM. WR-33278, the disulfide form of WR1065, was approximately twice as effective as the free thiol at denaturing nuclear proteins. The proposed mechanism for nucleoprotein denaturation is through direct interactions with protein cysteine groups with the formation of destabilizing protein-WR-1065 disulfides. In comparison to its effect on nuclear proteins in isolated nuclei, WR-1065 had only a very small effect on non-nuclear proteins of whole cells, isolated nuclear matrix, or the thiol-rich Ca (2+) ATPase of sarcoplasmic reticulum, indicating that WR-1065 can effectively denature protein only inside an intact nucleus, probably due to the increased concentration of the positively charged drug in the vicinity of DNA.

Neuroprotection against 6-OHDA toxicity in PC12 cells and mice through the Nrf2 pathway by a sesquiterpenoid from Tussilago farfara.

PubMed

Lee, Joohee; Song, Kwangho; Huh, Eugene; Oh, Myung Sook; Kim, Yeong Shik

2018-06-01

Oxidative stress plays a key role in neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Therefore, the nuclear factor-E2-related factor 2 (Nrf2), a key regulator of the antioxidative response, is considered to be important as a therapeutic target for neurodegenerative diseases. We investigated the underlying mechanism of Nrf2-mediated neuroprotective effects against oxidative stress in the PC12 cell line by 7β-(3-ethyl-cis-crotonoyloxy)-1α-(2-methylbutyryloxy)-3,14-dehydro-Z-notonipetranone (ECN), one of the sesquiterpenoids in Farfarae Flos. Pretreatment of PC12 cells with ECN had a protective effect against hydrogen peroxide (H 2 O 2 )- or 6-hydroxydopamine (6-OHDA)-induced cytotoxicity. ECN upregulated the ARE-luciferase activity and induced the mRNA expression of Nrf2 and antioxidant enzyme heme oxygenase-1 (HO-1). Knockdown of Nrf2 by small, interfering RNA (siRNA) abrogated the upregulation of HO-1, indicating that ECN had induced HO-1 via the Nrf2 pathway. Pretreatment with the thiol reducing agents, N-acetylcysteine (NAC) or dithiothreitol (DTT), attenuated Nrf2 activation and HO-1 expression. However, the non-thiol reducing antioxidant, Trolox, failed to inhibit HO-1 induction by ECN. These results suggest that ECN may directly interact with Kelch-like ECH-associated protein 1 (Keap1) and modify critical cysteine thiols present in the proteins responsible for Nrf2-mediated upregulation of HO-1. In a 6-OHDA-induced mouse model of PD, administration of ECN ameliorated motor impairments and dopaminergic neuronal damage. Taken together, ECN exerts neuroprotective effects by activating the Nrf2/HO-1 signaling pathway in both PC12 cells and mice. Thus, ECN, as an Nrf2 activator, could be an attractive therapeutic candidate for the neuroprotection or treatment of neurodegenerative diseases. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Determination of acidity and nucleophilicity in thiols by reaction with monobromobimane and fluorescence detection.

PubMed

Sardi, Florencia; Manta, Bruno; Portillo-Ledesma, Stephanie; Knoops, Bernard; Comini, Marcelo A; Ferrer-Sueta, Gerardo

2013-04-01

A method based on the differential reactivity of thiol and thiolate with monobromobimane (mBBr) has been developed to measure nucleophilicity and acidity of protein and low-molecular-weight thiols. Nucleophilicity of the thiolate is measured as the pH-independent second-order rate constant of its reaction with mBBr. The ionization constants of the thiols are obtained through the pH dependence of either second-order rate constant or initial rate of reaction. For readily available thiols, the apparent second-order rate constant is measured at different pHs and then plotted and fitted to an appropriate pH function describing the observed number of ionization equilibria. For less available thiols, such as protein thiols, the initial rate of reaction is determined in a wide range of pHs and fitted to the appropriate pH function. The method presented here shows excellent sensitivity, allowing the use of nanomolar concentrations of reagents. The method is suitable for scaling and high-throughput screening. Example determinations of nucleophilicity and pK(a) are presented for captopril and cysteine as low-molecular-weight thiols and for human peroxiredoxin 5 and Trypanosoma brucei monothiol glutaredoxin 1 as protein thiols. Copyright © 2013 Elsevier Inc. All rights reserved.

Low-molecular-weight thiols in streptomycetes and their potential role as antioxidants.

PubMed Central

Newton, G L; Fahey, R C; Cohen, G; Aharonowitz, Y

1993-01-01

The intracellular low-molecular-weight thiols present in five gram-positive Streptomyces species and one Flavobacterium species were analyzed by high-performance liquid chromatography after fluorescence labeling with monobromobimane. Bacteria were chosen to include penicillin and cephalosporin beta-lactam producers and nonproducers. No significant amount of glutathione was found in any of the streptomycetes. Major intracellular thiols in all strains examined were cysteine, coenzyme A, sulfide, thiosulfate, and an unknown thiol designated U17. Those streptomycetes that make beta-lactam antibiotics also produce significant amounts of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV), a key intermediate in their biosynthesis. In Streptomyces clavuligerus, a potent producer of beta-lactams, the level of ACV was low during the early phase of growth and increased rapidly toward the end of exponential growth, paralleling that of antibiotic production. These and other observations indicate that ACV does not function as a protective thiol in streptomycetes. U17 may have this role since it was the major thiol in all streptomycetes and appeared to occur at levels about 10-fold higher than those of the other thiols measured, including ACV. Purification and amino acid analysis of U17 indicated that it contains cysteine and an unusual amine that is not one of the common amino acids. This thiol is identical to an unknown thiol found previously in Micrococcus roseus and Streptomyces griseus. A high level of ergothioneine was found in Streptomyces lactamdurans, and several unidentified thiols were detected in this and other streptomycetes. PMID:8478335

Submicrodeterminations of thiols, disulphides and thiol esters in serum by using o-hydroxymercuribenzoic acid and dithiofluorescein

PubMed Central

Wroński, Mieczysław

1967-01-01

1. Methods are described for selective estimation of thiols, disulphides and thiol esters in standard solutions and in serum. The methods are based on the reaction with the excess of o-hydroxymercuribenzoic acid (HMB) in alkaline solution with subsequent addition of dithiofluorescein in excess and determination of the extinction at 588mμ. The sensitivity of the methods amounts to 1·5×10−9g.equiv. in 5ml. of final solution. Of results obtained on standard solutions 80% have the errors within the range ±4%. 2. It has been found that serum contains an unidentified substance (substance X) producing green complexes with dithiofluorescein which undergo decomposition on addition of formaldehyde. The correction for substance X must be estimated in a separate sample and taken into account. The concentration of substance X can be calculated from extinctions measured at 588mμ and 635mμ in the presence of dithiofluorescein in excess. 3. The selective determination of thiols and disulphides is based on different reaction rates with formaldehyde. The complexes between HMB and cysteine can be selectively decomposed by formaldehyde, and free glutathione can be selectively removed by formaldehyde in the presence of protein thiols. 4. Thiols are determined in the presence of triethylamine, thiols plus disulphides in the presence of triethylamine and sulphite, and thiols plus thiol esters in the presence of dimethylamine, with subsequent addition of ammonium sulphate. PMID:6049936

Metabolic glycoengineering: Sialic acid and beyond

PubMed Central

Du, Jian; Meledeo, M Adam; Wang, Zhiyun; Khanna, Hargun S; Paruchuri, Venkata D P; Yarema, Kevin J

2009-01-01

This report provides a perspective on metabolic glycoengineering methodology developed over the past two decades that allows natural sialic acids to be replaced with chemical variants in living cells and animals. Examples are given demonstrating how this technology provides the glycoscientist with chemical tools that are beginning to reproduce Mother Nature's control over complex biological systems – such as the human brain – through subtle modifications in sialic acid chemistry. Several metabolic substrates (e.g., ManNAc, Neu5Ac, and CMP-Neu5Ac analogs) can be used to feed flux into the sialic acid biosynthetic pathway resulting in numerous – and sometime quite unexpected – biological repercussions upon nonnatural sialoside display in cellular glycans. Once on the cell surface, ketone-, azide-, thiol-, or alkyne-modified glycans can be transformed with numerous ligands via bioorthogonal chemoselective ligation reactions, greatly increasing the versatility and potential application of this technology. Recently, sialic acid glycoengineering methodology has been extended to other pathways with analog incorporation now possible in surface-displayed GalNAc and fucose residues as well as nucleocytoplasmic O-GlcNAc-modified proteins. Finally, recent efforts to increase the “druggability” of sugar analogs used in metabolic glycoengineering, which have resulted in unanticipated “scaffold-dependent” activities, are summarized. PMID:19675091

4-Hydroxy-2(E)-nonenal metabolism differs in Apc(+/+) cells and in Apc(Min/+) cells: it may explain colon cancer promotion by heme iron.

PubMed

Baradat, Maryse; Jouanin, Isabelle; Dalleau, Sabine; Taché, Sylviane; Gieules, Mathilde; Debrauwer, Laurent; Canlet, Cécile; Huc, Laurence; Dupuy, Jacques; Pierre, Fabrice H F; Guéraud, Françoise

2011-11-21

Animal and epidemiological studies suggest that dietary heme iron would promote colorectal cancer. Oxidative properties of heme could lead to the formation of cytotoxic and genotoxic secondary lipid oxidation products, such as 4-hydroxy-2(E)-nonenal (HNE). This compound is more cytotoxic to mouse wild-type colon cells than to isogenic cells with a mutation on the adenomatous polyposis coli (APC) gene. The latter thus have a selective advantage, possibly leading to cancer promotion. This mutation is an early and frequent event in human colorectal cancer. To explain this difference, the HNE biotransformation capacities of the two cell types have been studied using radiolabeled and stable isotope-labeled HNE. Apc-mutated cells showed better biotransformation capacities than nonmutated cells did. Thiol compound conjugation capacities were higher for mutated cells, with an important advantage for the extracellular conjugation to cysteine. Both cells types were able to reduce HNE to 4-hydroxynonanal, a biotransformation pathway that has not been reported for other intestinal cells. Mutated cells showed higher capacities to oxidize 4-hydroxynonanal into 4-hydroxynonanoic acid. The mRNA expression of different enzymes involved in HNE metabolism such as aldehyde dehydrogenase 1A1, 2 and 3A1, glutathione transferase A4-4, or cystine transporter xCT was upregulated in mutated cells compared with wild-type cells. In conclusion, this study suggests that Apc-mutated cells are more efficient than wild-type cells in metabolizing HNE into thiol conjugates and 4-hydroxynonanoic acid due to the higher expression of key biotransformation enzymes. These differential biotransformation capacities would explain the differences of susceptibility between normal and Apc-mutated cells regarding secondary lipid oxidation products.

A technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates.

PubMed

Fontana, Jake; Spillmann, Christopher; Naciri, Jawad; Ratna, Banahalli R

2014-05-09

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles. The simple, robust and scalable technique efficiently functionalizes metallic nanoparticles with thiol-ligands in a miscible water/organic solvent mixture allowing for rapid grafting of thiol groups onto the gold nanoparticle surface. The hydrophobic ligands on the nanoparticles then quickly phase separate the nanoparticles from the aqueous based suspension and confine them to the air-fluid interface. This drives the ligand-capped nanoparticles to form monolayer domains at the air-fluid interface. The use of water-miscible organic solvents is important as it enables the transport of the nanoparticles from the interface onto template-free substrates. The flow is mediated by a surface tension gradient and creates macroscopic, high-density, monolayer nanoparticle-ligand films. This self-assembly technique may be generalized to include the use of particles of different compositions, size, and shape and may lead to an efficient assembly method to produce low-cost, macroscopic, high-density, monolayer nanoparticle films for wide-spread applications.

Soft Ultraviolet (UV) Photopatterning and Metallization of Self-Assembled Monolayers (SAMs) Formed from the Lipoic Acid Ester of α-Hydroxy-1-acetylpyrene: The Generality of Acid-Catalyzed Removal of Thiol-on-Gold SAMs using Soft UV Light.

PubMed

Pukenas, Laurynas; Prompinit, Panida; Nishitha, Boda; Tate, Daniel J; Singh, N D Pradeep; Wälti, Christoph; Evans, Stephen D; Bushby, Richard J

2017-05-31

Under a layer of 0.1 M HCl in isopropanol, soft ultraviolet (UV) (365 nm) photolysis of the thiol-on-gold self-assembled monolayer (SAM) derived from the lipoic acid ester of α-hydroxy-1-acetylpyrene results in the expected removal of the acetylpyrene protecting group. When photolyzing through a mask, this can be used to produce a patterned surface and, at a controlled electrochemical potential, it is then possible to selectively and reversibly electrodeposit copper on the photolyzed regions. Rather surprisingly, under these photolysis conditions, there is not only the expected photodeprotection of the ester but also partial removal of the lipoic acid layer which has been formed. In further studies, it is shown that this type of acid-catalyzed photoremoval of SAM layers by soft UV is a rather general phenomenon and results in the partial removal of the thiol-on-gold SAM layers derived from other ω-thiolated carboxylic acids. However, this phenomenon is chain-length dependent. Under conditions in which there is a ∼60% reduction in the thickness of the SAM derived from dithiobutyric acid, the SAM derived from mercaptoundecanoic acid is almost unaffected. The process by which the shorter-chain SAM layers are partially removed is not fully understood because these compounds do not absorb significantly in the 365 nm region of the spectrum! Significantly, this study shows that acid catalysis photolysis of thiol-on-gold SAMs needs to be used with caution.

A new ABC half-transporter in Leishmania major is involved in resistance to antimony.

PubMed

Manzano, J I; García-Hernández, R; Castanys, S; Gamarro, F

2013-08-01

The characterization of ABCI4, a new intracellular ATP-binding cassette (ABC) half-transporter in Leishmania major, is described. We show that ABCI4 is involved in heavy metal export, thereby conferring resistance to Pentostam, to Sb(III), and to As(III) and Cd(II). Parasites overexpressing ABCI4 showed a lower mitochondrial toxic effect of antimony by decreasing reactive oxygen species production and maintained higher values of both the mitochondrial electrochemical potential and total ATP levels with respect to controls. The ABCI4 half-transporter forms homodimers as determined by a coimmunoprecipitation assay. A combination of subcellular localization studies under a confocal microscope and a surface biotinylation assay using parasites expressing green fluorescent protein- and FLAG-tagged ABCI4 suggests that the transporter presents a dual localization in both mitochondria and the plasma membrane. Parasites overexpressing ABCI4 present an increased replication in mouse peritoneal macrophages. We have determined that porphyrins are substrates for ABCI4. Consequently, the overexpression of ABCI4 confers resistance to some toxic porphyrins, such as zinc-protoporphyrin, due to the lower accumulation resulting from a significant efflux, as determined using the fluorescent zinc-mesoporphyrin, a validated heme analog. In addition, ABCI4 has a significant ability to efflux thiol after Sb(III) incubation, thus meaning that ABCI4 could be considered to be a potential thiol-X-pump that is able to recognize metal-conjugated thiols. In summary, we have shown that this new ABC transporter is involved in drug sensitivity to antimony and other compounds by efflux as conjugated thiol complexes.

Thiol-Capped Gold Nanoparticles Swell-Encapsulated into Polyurethane as Powerful Antibacterial Surfaces Under Dark and Light Conditions

PubMed Central

Macdonald, Thomas J.; Wu, Ke; Sehmi, Sandeep K.; Noimark, Sacha; Peveler, William J.; du Toit, Hendrik; Voelcker, Nicolas H.; Allan, Elaine; MacRobert, Alexander J.; Gavriilidis, Asterios; Parkin, Ivan P.

2016-01-01

A simple procedure to develop antibacterial surfaces using thiol-capped gold nanoparticles (AuNPs) is shown, which effectively kill bacteria under dark and light conditions. The effect of AuNP size and concentration on photo-activated antibacterial surfaces is reported and we show significant size effects, as well as bactericidal activity with crystal violet (CV) coated polyurethane. These materials have been proven to be powerful antibacterial surfaces against both Gram-positive and Gram-negative bacteria. AuNPs of 2, 3 or 5 nm diameter were swell-encapsulated into PU before a coating of CV was applied (known as PU-AuNPs-CV). The antibacterial activity of PU-AuNPs-CV samples was tested against Staphylococcus aureus and Escherichia coli as representative Gram-positive and Gram-negative bacteria under dark and light conditions. All light conditions in this study simulated a typical white-light hospital environment. This work demonstrates that the antibacterial activity of PU-AuNPs-CV samples and the synergistic enhancement of photoactivity of triarylmethane type dyes is highly dependent on nanoparticle size and concentration. The most powerful PU-AuNPs-CV antibacterial surfaces were achieved using 1.0 mg mL−1 swell encapsulation concentrations of 2 nm AuNPs. After two hours, Gram-positive and Gram-negative bacteria were reduced to below the detection limit (>4 log) under dark and light conditions. PMID:27982122

Thiol/disulfide homeostasis in asphalt workers.

PubMed

Yilmaz, Ömer Hınç; Bal, Ceylan; Neşelioglu, Salim; Büyükşekerci, Murat; Gündüzöz, Meşide; Eren, Funda; Tutkun, Lutfiye; Yilmaz, Fatma Meric

2016-09-02

The aim of this study was to investigate thiol/disulfide homeostasis in asphalt workers who are exposed to polycyclic aromatic hydrocarbons occupationally. The study was carried out in 34 nonsmoker asphalt workers. Additionally, 35 healthy nonsmoker volunteers were recruited as control group. Thiol and disulfide concentrations were determined using the novel automated measurement method. Levels of urinary 1-OH-pyrene were analyzed by liquid chromatography. Disulfide/thiol ratio was significantly higher in exposed group (p = .034). Also, a positive correlation was detected between disulfide/thiol ratio and 1-OH-pyrene values (r = .249, p = .036). Thiol/disulfide homeostasis was found to be disturbed in asphalt workers. The novel test used in this study may be useful for evaluating the oxidative status in polycyclic aromatic hydrocarbon (PAH) exposure.

Development of Poly(Ethylene Glycol) Hydrogels for Salivary Gland Tissue Engineering Applications

PubMed Central

Shubin, Andrew D.; Felong, Timothy J.; Graunke, Dean; Ovitt, Catherine E.

2015-01-01

More than 40,000 patients are diagnosed with head and neck cancers annually in the United States with the vast majority receiving radiation therapy. Salivary glands are irreparably damaged by radiation therapy resulting in xerostomia, which severely affects patient quality of life. Cell-based therapies have shown some promise in mouse models of radiation-induced xerostomia, but they suffer from insufficient and inconsistent gland regeneration and accompanying secretory function. To aid in the development of regenerative therapies, poly(ethylene glycol) hydrogels were investigated for the encapsulation of primary submandibular gland (SMG) cells for tissue engineering applications. Different methods of hydrogel formation and cell preparation were examined to identify cytocompatible encapsulation conditions for SMG cells. Cell viability was much higher after thiol-ene polymerizations compared with conventional methacrylate polymerizations due to reduced membrane peroxidation and intracellular reactive oxygen species formation. In addition, the formation of multicellular microspheres before encapsulation maximized cell–cell contacts and increased viability of SMG cells over 14-day culture periods. Thiol-ene hydrogel-encapsulated microspheres also promoted SMG proliferation. Lineage tracing was employed to determine the cellular composition of hydrogel-encapsulated microspheres using markers for acinar (Mist1) and duct (Keratin5) cells. Our findings indicate that both acinar and duct cell phenotypes are present throughout the 14 day culture period. However, the acinar:duct cell ratios are reduced over time, likely due to duct cell proliferation. Altogether, permissive encapsulation methods for primary SMG cells have been identified that promote cell viability, proliferation, and maintenance of differentiated salivary gland cell phenotypes, which allows for translation of this approach for salivary gland tissue engineering applications. PMID:25762214

Synthesis of thiolated chitosan and preparation nanoparticles with sodium alginate for ocular drug delivery.

PubMed

Zhu, Xuan; Su, Meiqin; Tang, Shaoheng; Wang, Lingsong; Liang, Xinfang; Meng, Feihong; Hong, Ying; Xu, Zhiran

2012-01-01

The goal of the present study was to synthesize mucoadhesive polymer - thiolated chitosan (TCS) from chitosan (CS), then prepared CS/TCS-sodium alginate nanoparticles (CS/TCS-SA NPs), determined which was more potential for ocular drug delivery. A new method for preparing TCS was developed, and the characteristics were determined using Fourier transform infrared spectroscopy and the degree of thiol immobilized was measured by Ellman's reagent. Human corneal epithelium (HCE) cells were incubated with different concentrations of TCS for 48 h to determine the cell viabilities. CS/TCS-SA NPs were prepared and optimized by a modified ionic gelation method. The particle sizes, zeta potentials, Scanning electron microscopy images, mucoadhesion, in vitro cell uptake and in vivo studies of the two types of NP were compared. The new method enabled a high degree of thiol substitution of TCS, up to 1,411.01±4.02 μmol/g. In vitro cytocompatibility results suggest that TCS is nontoxic. Compared to CS-SA NPs, TCS-SA NPs were more stable, with higher mucoadhesive properties and could deliver greater amounts of drugs into HCE cells in vitro and cornea in vivo. TCS-SA NPs have better delivery capability, suggesting they have good potential for ocular drug delivery applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rouyer-Fessard, P.; Garel, M.C.; Domenget, C.

The soluble pool of alpha hemoglobin chains present in blood or bone marrow cells was measured with a new affinity method using a specific probe, beta A hemoglobin chain labeled with ({sup 3}H)N-ethylmaleimide. This pool of soluble alpha chains was 0.067 {plus minus} 0.017% of hemoglobin in blood of normal adult, 0.11 {plus minus} 0.03% in heterozygous beta thalassemia and ranged from 0.26 to 1.30% in homozygous beta thalassemia intermedia. This elevated pool of soluble alpha chains observed in human beta thalassemia intermedia decreased 33-fold from a value of 10% of total hemoglobin in bone marrow cells to 0.3% inmore » the most dense red blood cells. The amount of insoluble alpha chains was measured by using the polyacrylamide gel electrophoresis in urea and Triton X-100. In beta thalassemia intermedia the amount of insoluble alpha chains was correlated with the decreased spectrin content of red cell membrane and was associated with a decrease in ankyrin and with other abnormalities of the electrophoretic pattern of membrane proteins. The loss and topology of the reactive thiol groups of membrane proteins was determined by using ({sup 3}H)N-ethylmaleimide added to membrane ghosts prior to urea and Triton X-100 electrophoresis. Spectrin and ankyrin were the major proteins with the most important decrease of thiol groups.« less

Zinc and the modulation of redox homeostasis

PubMed Central

Oteiza, Patricia I.

2012-01-01

Zinc, a redox inactive metal, has been long viewed as a component of the antioxidant network, and growing evidence points to its involvement in redox-regulated signaling. These actions are exerted through several mechanisms based on the unique chemical and functional properties of zinc. Overall, zinc contributes to maintain the cell redox balance through different mechanisms including: i) the regulation of oxidant production and metal-induced oxidative damage; ii) the dynamic association of zinc with sulfur in protein cysteine clusters, from which the metal can be released by nitric oxide, peroxides, oxidized glutathione and other thiol oxidant species; iii) zinc-mediated induction of the zinc-binding protein metallothionein, which releases the metal under oxidative conditions and act per se scavenging oxidants; iv) the involvement of zinc in the regulation of glutathione metabolism and of the overall protein thiol redox status; and v) a direct or indirect regulation of redox signaling. Findings of oxidative stress, altered redox signaling, and associated cell/tissue disfunction in cell and animal models of zinc deficiency, stress the relevant role of zinc in the preservation of cell redox homeostasis. However, while the participation of zinc in antioxidant protection, redox sensing, and redox-regulated signaling is accepted, the involved molecules, targets and mechanisms are still partially known and the subject of active research. PMID:22960578

Chondrogenic differentiation potential of human mesenchymal stem cells photoencapsulated within poly(ethylene glycol)-arginine-glycine-aspartic acid-serine thiol-methacrylate mixed-mode networks.

PubMed

Salinas, Chelsea N; Cole, Brook B; Kasko, Andrea M; Anseth, Kristi S

2007-05-01

Chondrogenesis of human mesenchymal stem cells (hMSCs) encapsulated in poly(ethylene glycol) (PEG)-based hydrogels was studied in the presence and absence of 5 ng/mL transforming growth factor beta and chondrogenic medium to better understand the role of the gel environment on this process. The lack of any cell-polymer interactions led to decreasing cell viability, as measured using adenosine triphosphate, over a 14-day period. The extent of chondrogenic differentiation was evaluated by immunostaining, and although viability dramatically decreased, cells cultured in chondrogenic differentiation medium expressed higher levels of collagen type II. Cells cultured in hMSC control medium remained undifferentiated and continued to express CD105, a MSC marker. To increase cell survival, arginine-glycine-aspartic acid-serine (RGDS) was incorporated into gels using a novel mixed-mode thiol-ene reaction by synthesizing a cysteine-cysteine-arginine-glycine-aspartic acid-serine-cysteine-cysteine-glycine, N-terminus to C-terminus peptide sequence with pendant cysteine residues. A concentration of 5 mM RGDS incorporated into the network maintained 75% viability in control cultures. Further studies demonstrated that 5-mM RGDS chondrogenic cultures had greater gene expression for aggrecan and collagen II in conjunction with producing twice as much glycosaminoglycan as 0-mM chondrogenic cultures and 7 times that of control cultures. Incorporation of this peptide sequence not only allows for sustained viability, but also contributes to initiating chondrogenesis.

Reaction kinetics and targeting to cellular glutathione S-transferase of the glutathione peroxidase mimetic PhSeZnCl and its D,L-polylactide microparticle formulation.

PubMed

Bartolini, D; Piroddi, M; Tidei, C; Giovagnoli, S; Pietrella, D; Manevich, Y; Tew, K D; Giustarini, D; Rossi, R; Townsend, D M; Santi, C; Galli, F

2015-01-01

Catalytic properties and cellular effects of the glutathione peroxidase (GPx)-mimetic compound PhSeZnCl or its d,l-lactide polymer microencapsulation form (M-PhSeZnCl) were investigated and compared with the prototypical Se-organic compounds ebselen and diselenide (PhSe)2. PhSeZnCl was confirmed to catalyze the ping-pong reaction of GPx with higher Vmax than ebselen and (PhSe)2, but the catalytic efficiency calculated for the cosubstrates glutathione (GSH) and H2O2, and particularly the high reactivity against thiols (lowest KM for GSH in the series of test molecules), suggested poor biological applicability of PhSeZnCl as a GPx mimetic. Cytotoxicity of PhSeZnCl was demonstrated in various cancer cell lines via increased reactive oxygen species (ROS) generation, depletion of intracellular thiols, and induction of apoptosis. Experiments carried out in GSH S-transferase P (GSTP)-overexpressing K562 human erythroleukemia cells and in GSTP1-1-knockout murine embryonic fibroblasts (MEFs) demonstrated that this cytosolic enzyme represents a preferential target of the redox disturbances produced by this Se-compound with a key role in controlling H2O2 generation and the perturbation of stress/survival kinase signaling. Microencapsulation was adopted as a strategy to control the thiol reactivity and oxidative stress effects of PhSeZnCl, then assessing applications alternative to anticancer. The uptake of this "depowered" GPx-mimetic formulation, which occurred through an endocytosis-like mechanism, resulted in a marked reduction of cytotoxicity. In MCF-7 cells transfected with different allelic variants of GSTP, M-PhSeZnCl lowered the burst of cellular ROS induced by the exposure to extracellular H2O2, and the extent of this effect changed between the GSTP variants. Microencapsulation is a straightforward strategy to mitigate the toxicity of thiol-reactive Se-organic drugs that enhanced the antioxidant and cellular protective effects of PhSeZnCl. A mechanistic linkage of these effects with the expression pattern and signaling properties of GSTP . This has overcome the GPx-mimetic paradigm proposed for Se-organic drugs with a more pragmatic concept of GSTP signaling modulators. Copyright © 2014 Elsevier Inc. All rights reserved.

Reaction kinetics and targeting to cellular glutathione S-transferase of the glutathione peroxidase mimetic PhSeZnCl and its d,l-polylactide microparticle formulation

PubMed Central

Bartolini, D.; Piroddi, M.; Tidei, C.; Giovagnoli, S.; Pietrella, D.; Manevich, Y.; Tew, K.D.; Giustarini, D.; Rossi, R.; Townsend, D.M.; Santi, C.; Galli, F.

2015-01-01

Catalytic properties and cellular effects of the glutathione peroxidase (GPx)-mimetic compound PhSeZnCl or its d,l-lactide polymer microencapsulation form (M-PhSeZnCl) were investigated and compared with the prototypical Se-organic compounds ebselen and diselenide (PhSe)2. PhSeZnCl was confirmed to catalyze the ping-pong reaction of GPx with higher Vmax than ebselen and (PhSe)2, but the catalytic efficiency calculated for the cosubstrates glutathione (GSH) and H2O2, and particularly the high reactivity against thiols (lowest KM for GSH in the series of test molecules), suggested poor biological applicability of PhSeZnCl as a GPx mimetic. Cytotoxicity of PhSeZnCl was demonstrated in various cancer cell lines via increased reactive oxygen species (ROS) generation, depletion of intracellular thiols, and induction of apoptosis. Experiments carried out in GSH S-transferase P (GSTP)-overexpressing K562 human erythroleukemia cells and in GSTP1-1-knockout murine embryonic fibroblasts (MEFs) demonstrated that this cytosolic enzyme represents a preferential target of the redox disturbances produced by this Se-compound with a key role in controlling H2O2 generation and the perturbation of stress/survival kinase signaling. Microencapsulation was adopted as a strategy to control the thiol reactivity and oxidative stress effects of PhSeZnCl, then assessing applications alternative to anticancer. The uptake of this “depowered” GPx-mimetic formulation, which occurred through an endocytosis-like mechanism, resulted in a marked reduction of cytotoxicity. In MCF-7 cells transfected with different allelic variants of GSTP, M-PhSeZnCl lowered the burst of cellular ROS induced by the exposure to extracellular H2O2, and the extent of this effect changed between the GSTP variants. Microencapsulation is a straightforward strategy to mitigate the toxicity of thiol-reactive Se-organic drugs that enhanced the antioxidant and cellular protective effects of PhSeZnCl. A mechanistic linkage of these effects with the expression pattern and signaling properties of GSTP. This has overcome the GPx-mimetic paradigm proposed for Se-organic drugs with a more pragmatic concept of GSTP signaling modulators. PMID:25452145

Patterned self-assembled monolayers of alkanethiols on copper nanomembranes by submerged laser ablation

NASA Astrophysics Data System (ADS)

Rhinow, Daniel; Hampp, Norbert A.

2012-06-01

Self-assembled monolayers (SAMs) of alkanethiols are major building blocks for nanotechnology. SAMs provide a functional interface between electrodes and biomolecules, which makes them attractive for biochip fabrication. Although gold has emerged as a standard, copper has several advantages, such as compatibility with semiconductors. However, as copper is easily oxidized in air, patterning SAMs on copper is a challenging task. In this work we demonstrate that submerged laser ablation (SLAB) is well-suited for this purpose, as thiols are exchanged in-situ, avoiding air exposition. Using different types of ω-substituted alkanethiols we show that alkanethiol SAMs on copper surfaces can be patterned using SLAB. The resulting patterns were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Both methods indicate that the intense laser beam promotes the exchange of thiols at the copper surface. Furthermore, we present a procedure for the production of free-standing copper nanomembranes, oxidation-protected by alkanethiol SAMs. Incubation of copper-coated mica in alkanethiol solutions leads to SAM formation on both surfaces of the copper film due to intercalation of the organic molecules. Corrosion-protected copper nanomembranes were floated onto water, transferred to electron microscopy grids, and subsequently analyzed by electron energy loss spectroscopy (EELS).

DNA-modified electrodes fabricated using copper-free click chemistry for enhanced protein detection.

PubMed

Furst, Ariel L; Hill, Michael G; Barton, Jacqueline K

2013-12-31

A method of DNA monolayer formation has been developed using copper-free click chemistry that yields enhanced surface homogeneity and enables variation in the amount of DNA assembled; extremely low-density DNA monolayers, with as little as 5% of the monolayer being DNA, have been formed. These DNA-modified electrodes (DMEs) were characterized visually, with AFM, and electrochemically, and were found to facilitate DNA-mediated reduction of a distally bound redox probe. These low-density monolayers were found to be more homogeneous than traditional thiol-modified DNA monolayers, with greater helix accessibility through an increased surface area-to-volume ratio. Protein binding efficiency of the transcriptional activator TATA-binding protein (TBP) was also investigated on these surfaces and compared to that on DNA monolayers formed with standard thiol-modified DNA. Our low-density monolayers were found to be extremely sensitive to TBP binding, with a signal decrease in excess of 75% for 150 nM protein. This protein was detectable at 4 nM, on the order of its dissociation constant, with our low-density monolayers. The improved DNA helix accessibility and sensitivity of our low-density DNA monolayers to TBP binding reflects the general utility of this method of DNA monolayer formation for DNA-based electrochemical sensor development.

Site-dependent atomic and molecular affinities of hydrocarbons, amines and thiols on diamond nanoparticles

NASA Astrophysics Data System (ADS)

Lai, Lin; Barnard, Amanda S.

2016-04-01

Like many of the useful nanomaterials being produced on the industrial scale, the surface of diamond nanoparticles includes a complicated mixture of various atomic and molecular adsorbates, attaching to the facets following synthesis. Some of these adsorbates may be functional, and adsorption is encouraged to promote applications in biotechnology and nanomedicine, but others are purely adventurous and must be removed prior to use. In order to devise more effective treatments it is advantageous to know the relative strength of the interactions of the adsorbates with the surface, and ideally how abundant they are likely to be under different conditions. In this paper we use a series of explicit electronic structure simulations to map the distribution of small hydrocarbons, amines and thiols on a 2.9 nm diamond nanoparticle, with atomic level resolution, in 3-D. We find a clear relationship between surface reconstructions, facet orientation, and the distribution of the different adsorbates; with a greater concentration expected on the (100) and (110) facets, particularly when the supersaturation in the reservoir is high. Adsorption on the (111) facets is highly unlikely, suggesting that controlled graphitization may be a useful stage in the cleaning and treatment of nanodiamonds, prior to the deliberate coating with functional adsorbates needed for drug delivery applications.

Platinum nanocatalysts prepared with different surfactants for C1-C3 alcohol oxidations and their surface morphologies by AFM

NASA Astrophysics Data System (ADS)

Ertan, Salih; Şen, Fatih; Şen, Selda; Gökağaç, Gülsün

2012-06-01

In this study, platinum nanoparticle catalysts have been prepared using PtCl4 as a starting material and 1-octanethiol, 1-decanethiol, 1-dodecanethiol, and 1-hexadecanethiol as surfactants for methanol, ethanol, and 2-propanol oxidation reactions. The structure, particle sizes, and surface morphologies of the catalysts were characterized by X-ray diffraction (XRD), atomic force microscopy and transmission electron microscopy (TEM). XRD and TEM results indicate that all prepared catalysts have a face-centered cubic structure and are homogeneously dispersed on the carbon support with a narrow size distribution (2.0-1.3 nm). X-ray photoelectron spectra of the catalysts were examined and it is found that platinum has two different oxidation states, Pt (0) and Pt(IV), oxygen and sulfur compounds are H2Oads and OHads, bound and unbound thiols. The electrochemical and electrocatalytic properties of these catalysts were investigated with respect to C1-C3 alcohol oxidations by cyclic voltammetry and chronoamperometry. The highest electrocatalytic activity was obtained from catalyst I which was prepared with 1-octanethiol. This may be attributed to a decrease in the ratio of bound to unbound thiol species increase in Pt (0)/Pt(IV), H2Oads/OHads ratios, electrochemical surface area, CO tolerance and percent platinum utility.

Spectrophotometric Determination of Phenolic Antioxidants in the Presence of Thiols and Proteins.

PubMed

Avan, Aslı Neslihan; Demirci Çekiç, Sema; Uzunboy, Seda; Apak, Reşat

2016-08-12

Development of easy, practical, and low-cost spectrophotometric methods is required for the selective determination of phenolic antioxidants in the presence of other similar substances. As electron transfer (ET)-based total antioxidant capacity (TAC) assays generally measure the reducing ability of antioxidant compounds, thiols and phenols cannot be differentiated since they are both responsive to the probe reagent. In this study, three of the most common TAC determination methods, namely cupric ion reducing antioxidant capacity (CUPRAC), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt/trolox equivalent antioxidant capacity (ABTS/TEAC), and ferric reducing antioxidant power (FRAP), were tested for the assay of phenolics in the presence of selected thiol and protein compounds. Although the FRAP method is almost non-responsive to thiol compounds individually, surprising overoxidations with large positive deviations from additivity were observed when using this method for (phenols + thiols) mixtures. Among the tested TAC methods, CUPRAC gave the most additive results for all studied (phenol + thiol) and (phenol + protein) mixtures with minimal relative error. As ABTS/TEAC and FRAP methods gave small and large deviations, respectively, from additivity of absorbances arising from these components in mixtures, mercury(II) compounds were added to stabilize the thiol components in the form of Hg(II)-thiol complexes so as to enable selective spectrophotometric determination of phenolic components. This error compensation was most efficient for the FRAP method in testing (thiols + phenols) mixtures.

An evaluation of thiol/disulphide homeostasis in patients with psoriasis

PubMed Central

Yorulmaz, Ahu; Erdogan, Serpil; Cakmak, Seray Kulcu; Guney, Elif; Sen, Orhan; Erel, Ozcan

2017-01-01

Introduction The role of oxidative stress in the pathogenesis of psoriasis has been investigated in previous studies with conflicting results. On the other hand, well-established treatments currently used in psoriasis exert their effects via a boost of oxidative stress. Recently, a strong positive association between psoriasis, metabolic syndrome and dyslipidemia has also been described showing the complex nature of the disease. Aim To examine thiol/disulphide homeostasis, a newly developed homeostasis assay in psoriasis and evaluate the possible association between thiol/disulphide homeostasis and dyslipidemia in psoriasis. Material and methods The study population included 92 psoriasis patients and 71 healthy subjects. Serum native thiol, total thiol and disulphide levels were investigated in patients with psoriasis and in healthy subjects. In addition, lipid profile (serum total cholesterol, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol) levels were investigated in both groups. The association between thiol-disulphide parameters and dyslipidemia was also evaluated. Results Serum total cholesterol and triglyceride levels were found to be higher in patients with psoriasis than in the healthy group. Lower plasma disulphide and higher native thiol levels were found in patients with psoriasis indicating an antioxidant status. Conclusions To our knowledge, this is the first study showing the shift of dynamic thiol/disulphide homeostasis towards the thiol form in psoriasis which indicate higher antioxidant status. PMID:29507562

A chiral self-assembled monolayer derived from a resolving agent and its performance as a crystallization template for an organic compound from organic solvents.

PubMed

Bejarano-Villafuerte, Ángela; van der Meijden, Maarten W; Lingenfelder, Magalí; Wurst, Klaus; Kellogg, Richard M; Amabilino, David B

2012-12-07

A new chiral nonracemic thiol derived from a popular acidic resolving agent that incorporates a cyclic disubstituted phosphate group (phencyphos) has been prepared in enantiomerically pure form. The stereochemistry and absolute configuration were established by performing a single-crystal X-ray structural analysis of a synthetic intermediate. The thiol compound was used for the preparation of self-assembled monolayers (SAMs) on both monocrystalline and polycrystalline metallic gold, which have very different surface roughness. The monolayers were used to promote the nucleation and growth of crystals from nonaqueous solutions of an organic molecule (the parent phencyphos) of similar structure to the compound present in the monolayer. The template layers influence the nucleation and growth of the phencyphos crystals despite the lack of two-dimensional order in the surfaces. Heterogeneous nucleation of phencyphos takes place upon evaporation of either CHCl(3) or isopropanol solutions of the compound on the SAM surfaces, where the evaporation rate merely influences the size and homogeneity of the crystals. The roughness of the surface also plays an important role; the polycrystalline gold produces more homogeneous samples because of the greater number of nucleation sites. Clear evidence for nucleation and growth on the surfaces is shown by scanning electron microscopy. The variation in crystal form achieved by using different surfaces and solvents suggests that the layers are applicable for the preparation of organic crystals from organic solutions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Transcriptional Response of Lactobacillus sanfranciscensis DSM 20451T and Its tcyB Mutant Lacking a Functional Cystine Transporter to Diamide Stress

PubMed Central

Stetina, Mandy; Behr, Jürgen

2014-01-01

As a result of its strong adaptation to wheat and rye sourdoughs, Lactobacillus sanfranciscensis has the smallest genome within the genus Lactobacillus. The concomitant absence of some important antioxidative enzymes and the inability to synthesize glutathione suggest a role of cystine transport in maintenance of an intracellular thiol balance. Diamide [synonym 1,1′-azobis(N,N-dimethylformamide)] disturbs intracellular and membrane thiol levels in oxidizing protein thiols depending on its initial concentration. In this study, RNA sequencing was used to reveal the transcriptional response of L. sanfranciscensis DSM 20451T (wild type [WT]) and its ΔtcyB mutant with a nonfunctional cystine transporter after thiol stress caused by diamide. Along with the different expression of genes involved in amino acid starvation, pyrimidine synthesis, and energy production, our results show that thiol stress in the wild type can be compensated through activation of diverse chaperones and proteases whereas the ΔtcyB mutant shifts its metabolism in the direction of survival. Only a small set of genes are significantly differentially expressed between the wild type and the mutant. In the WT, mainly genes which are associated with a heat shock response are upregulated whereas glutamine import and synthesis genes are downregulated. In the ΔtcyB mutant, the whole opp operon was more highly expressed, as well as a protein which probably includes enzymes for methionine transport. The two proteins encoded by spxA and nrdH, which are involved in direct or indirect oxidative stress responses, are also upregulated in the mutant. This work emphasizes that even in the absence of definitive antioxidative enzymes, bacteria with a small genome and a high frequency of gene inactivation and elimination use small molecules such as the cysteine/cystine couple to overcome potential cell damage resulting from oxidative stress. PMID:24795368

The transcriptional response of Lactobacillus sanfranciscensis DSM 20451T and its tcyB mutant lacking a functional cystine transporter to diamide stress.

PubMed

Stetina, Mandy; Behr, Jürgen; Vogel, Rudi F

2014-07-01

As a result of its strong adaptation to wheat and rye sourdoughs, Lactobacillus sanfranciscensis has the smallest genome within the genus Lactobacillus. The concomitant absence of some important antioxidative enzymes and the inability to synthesize glutathione suggest a role of cystine transport in maintenance of an intracellular thiol balance. Diamide [synonym 1,1'-azobis(N,N-dimethylformamide)] disturbs intracellular and membrane thiol levels in oxidizing protein thiols depending on its initial concentration. In this study, RNA sequencing was used to reveal the transcriptional response of L. sanfranciscensis DSM 20451(T) (wild type [WT]) and its ΔtcyB mutant with a nonfunctional cystine transporter after thiol stress caused by diamide. Along with the different expression of genes involved in amino acid starvation, pyrimidine synthesis, and energy production, our results show that thiol stress in the wild type can be compensated through activation of diverse chaperones and proteases whereas the ΔtcyB mutant shifts its metabolism in the direction of survival. Only a small set of genes are significantly differentially expressed between the wild type and the mutant. In the WT, mainly genes which are associated with a heat shock response are upregulated whereas glutamine import and synthesis genes are downregulated. In the ΔtcyB mutant, the whole opp operon was more highly expressed, as well as a protein which probably includes enzymes for methionine transport. The two proteins encoded by spxA and nrdH, which are involved in direct or indirect oxidative stress responses, are also upregulated in the mutant. This work emphasizes that even in the absence of definitive antioxidative enzymes, bacteria with a small genome and a high frequency of gene inactivation and elimination use small molecules such as the cysteine/cystine couple to overcome potential cell damage resulting from oxidative stress. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Protein S-Mycothiolation Functions as Redox-Switch and Thiol Protection Mechanism in Corynebacterium glutamicum Under Hypochlorite Stress

PubMed Central

Chi, Bui Khanh; Busche, Tobias; Van Laer, Koen; Bäsell, Katrin; Becher, Dörte; Clermont, Lina; Seibold, Gerd M.; Persicke, Marcus; Kalinowski, Jörn; Messens, Joris

2014-01-01

Abstract Aims: Protein S-bacillithiolation was recently discovered as important thiol protection and redox-switch mechanism in response to hypochlorite stress in Firmicutes bacteria. Here we used transcriptomics to analyze the NaOCl stress response in the mycothiol (MSH)-producing Corynebacterium glutamicum. We further applied thiol-redox proteomics and mass spectrometry (MS) to identify protein S-mycothiolation. Results: Transcriptomics revealed the strong upregulation of the disulfide stress σH regulon by NaOCl stress in C. glutamicum, including genes for the anti sigma factor (rshA), the thioredoxin and MSH pathways (trxB1, trxC, cg1375, trxB, mshC, mca, mtr) that maintain the redox balance. We identified 25 S-mycothiolated proteins in NaOCl-treated cells by liquid chromatography–tandem mass spectrometry (LC-MS/MS), including 16 proteins that are reversibly oxidized by NaOCl in the thiol-redox proteome. The S-mycothiolome includes the methionine synthase (MetE), the maltodextrin phosphorylase (MalP), the myoinositol-1-phosphate synthase (Ino1), enzymes for the biosynthesis of nucleotides (GuaB1, GuaB2, PurL, NadC), and thiamine (ThiD), translation proteins (TufA, PheT, RpsF, RplM, RpsM, RpsC), and antioxidant enzymes (Tpx, Gpx, MsrA). We further show that S-mycothiolation of the thiol peroxidase (Tpx) affects its peroxiredoxin activity in vitro that can be restored by mycoredoxin1. LC-MS/MS analysis further identified 8 proteins with S-cysteinylations in the mshC mutant suggesting that cysteine can be used for S-thiolations in the absence of MSH. Innovation and Conclusion: We identified widespread protein S-mycothiolations in the MSH-producing C. glutamicum and demonstrate that S-mycothiolation reversibly affects the peroxidase activity of Tpx. Interestingly, many targets are conserved S-thiolated across bacillithiol- and MSH-producing bacteria, which could become future drug targets in related pathogenic Gram-positives. Antioxid. Redox Signal. 20, 589–605. PMID:23886307

Intercalation of gaseous thiols and sulfides into Ag+ ion-exchanged aluminum dihydrogen triphosphate.

PubMed

Hayashi, Aki; Saimen, Hiroki; Watanabe, Nobuaki; Kimura, Hitomi; Kobayashi, Ayumi; Nakayama, Hirokazu; Tsuhako, Mitsutomo

2005-08-02

Ag(+) ion-exchanged layered aluminum dihydrogen triphosphate (AlP) with the interlayer distance of 0.85 nm was synthesized by the ion-exchange of proton in triphosphate with Ag(+) ion. The amount of exchanged Ag(+) ion depended on the concentration of AgNO(3) aqueous solution. Ag(+) ion-exchanged AlP adsorbed gaseous thiols and sulfides into the interlayer region. The adsorption amounts of thiols were more than those of sulfides, thiols with one mercapto group > thiol with two mercapto groups > sulfides, and depended on the amount of exchanged Ag(+) ion in the interlayer region. The thiols with one mercapto group were intercalated to expand the interlayer distance of Ag(+) ion-exchanged AlP, whereas there was no expansion in the adsorption of sulfide. In the case of thiol with two mercapto groups, there was observed contraction of the interlayer distance through the bridging with Ag(+) ions of the upper and lower sides of the interlayer region.

Label-free all-electronic biosensing in microfluidic systems

NASA Astrophysics Data System (ADS)

Stanton, Michael A.

Label-free, all-electronic detection techniques offer great promise for advancements in medical and biological analysis. Electrical sensing can be used to measure both interfacial and bulk impedance changes in conducting solutions. Electronic sensors produced using standard microfabrication processes are easily integrated into microfluidic systems. Combined with the sensitivity of radiofrequency electrical measurements, this approach offers significant advantages over competing biological sensing methods. Scalable fabrication methods also provide a means of bypassing the prohibitive costs and infrastructure associated with current technologies. We describe the design, development and use of a radiofrequency reflectometer integrated into a microfluidic system towards the specific detection of biologically relevant materials. We developed a detection protocol based on impedimetric changes caused by the binding of antibody/antigen pairs to the sensing region. Here we report the surface chemistry that forms the necessary capture mechanism. Gold-thiol binding was utilized to create an ordered alkane monolayer on the sensor surface. Exposed functional groups target the N-terminus, affixing a protein to the monolayer. The general applicability of this method lends itself to a wide variety of proteins. To demonstrate specificity, commercially available mouse anti- Streptococcus Pneumoniae monoclonal antibody was used to target the full-length recombinant pneumococcal surface protein A, type 2 strain D39 expressed by Streptococcus Pneumoniae. We demonstrate the RF response of the sensor to both the presence of the surface decoration and bound SPn cells in a 1x phosphate buffered saline solution. The combined microfluidic sensor represents a powerful platform for the analysis and detection of cells and biomolecules.

Moderate physical exercise induces the oxidation of human blood protein thiols.

PubMed

Inayama, Takayo; Oka, Jun; Kashiba, Misato; Saito, Makoto; Higuchi, Mitsuru; Umegaki, Keizo; Yamamoto, Yorihiro; Matsuda, Mitsuo

2002-03-15

Exercise is known to induce the oxidation of blood low-molecular-weight (LMW) thiols such as reduced glutathione (GSH). We previously reported that full-marathon running induced a decrease in human plasma levels of protein-bound sulfhydryl groups (p-SHs). Moderate exercise, a 30-min running at the intensity of the individual ventilatory threshold, performed by untrained healthy females caused a significant decrease in erythrocyte levels of p-SHs (mostly hemoglobin cysteine residues) and LMW thiols, but their levels returned to each baseline by 2 h. No significant change in plasma LMW thiols was observed. However, plasma levels of p-SHs significantly decreased after running and remained unchanged after 24 h. These results suggest that moderate exercise causes the oxidation of blood thiols, especially protein-bound thiols.

The inhibition of human T cell proliferation by the caspase inhibitor z-VAD-FMK is mediated through oxidative stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajah, T.; Chow, S.C., E-mail: chow.sek.chuen@monash.edu

2014-07-15

The caspase inhibitor benzyloxycarbony (Cbz)-L-Val-Ala-Asp (OMe)-fluoromethylketone (z-VAD-FMK) has recently been shown to inhibit T cell proliferation without blocking caspase-8 and caspase-3 activation in primary T cells. We showed in this study that z-VAD-FMK treatment leads to a decrease in intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) levels in activated T cells. The inhibition of anti-CD3-mediated T cell proliferation induced by z-VAD-FMK was abolished by the presence of low molecular weight thiols such as GSH, N-acetylcysteine (NAC) and L-cysteine, whereas D-cysteine which cannot be metabolised to GSH has no effect. These results suggest that the depletionmore » of intracellular GSH is the underlying cause of z-VAD-FMK-mediated inhibition of T cell activation and proliferation. The presence of exogenous GSH also attenuated the inhibition of anti-CD3-induced CD25 and CD69 expression mediated by z-VAD-FMK. However, none of the low molecular weight thiols were able to restore the caspase-inhibitory properties of z-VAD-FMK in activated T cells where caspase-8 and caspase-3 remain activated and processed into their respective subunits in the presence of the caspase inhibitor. This suggests that the inhibition of T cell proliferation can be uncoupled from the caspase-inhibitory properties of z-VAD-FMK. Taken together, the immunosuppressive effects in primary T cells mediated by z-VAD-FMK are due to oxidative stress via the depletion of GSH.« less

Furoxans (1,2,5-Oxadiazole-N-Oxides) as Novel NO Mimetic Neuroprotective and Procognitive Agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiefer, Isaac T.; VandeVrede, Lawren; Fa

2012-08-31

Furoxans (1,2,5-oxadiazole-N-oxides) are thiol-bioactivated NO-mimetics that have not hitherto been studied in the CNS. Incorporation of varied substituents adjacent to the furoxan ring system led to modulation of reactivity toward bioactivation, studied by HPLC-MS/MS analysis of reaction products. Attenuated reactivity unmasked the cytoprotective actions of NO in contrast to the cytotoxic actions of higher NO fluxes reported previously for furoxans. Neuroprotection was observed in primary neuronal cell cultures following oxygen glucose deprivation (OGD). Neuroprotective activity was observed to correlate with thiol-dependent bioactivation to produce NO{sub 2}{sup -}, but not with depletion of free thiol itself. Neuroprotection was abrogated upon cotreatmentmore » with a sGC inhibitor, ODQ, thus supporting activation of the NO/sGC/CREB signaling cascade by furoxans. Long-term potentiation (LTP), essential for learning and memory, has been shown to be potentiated by NO signaling, therefore, a peptidomimetic furoxan was tested in hippocampal slices treated with oligomeric amyloid-{beta} peptide (A{beta}) and was shown to restore synaptic function. The novel observation of furoxan activity of potential therapeutic use in the CNS warrants further studies.« less

Rapid detection of food pathogens using RNA aptamers-immobilized slide.

PubMed

Maeng, Jin-Soo; Kim, Namsoo; Kim, Chong-Tai; Han, Seung Ryul; Lee, Young Ju; Lee, Seong-Wook; Lee, Myung-Hyun; Cho, Yong-Jin

2012-07-01

The purpose of this study was to develop a simple and rapid detection system for foodborne bacteria, which consisted of an optical microscope and its slide chip with artificial antibodies, or RNA aptamers. From an RNA pool, three each RNA aptamers were built by the method of SELEX (systematic evolution of ligands by exponential enrichment) for components of cell wall, LPS (lipopolysaccharide) from E. coli O157:H7, teichoic acid from Staphylococcus aureus and a cell membrane protein of OmpC from Salmonella typhimurium, respectively. These aptamers were hybridized with thiol-conjugated 16 dT-linker molecules in order to be immobilized on silver surface which was, in advance, fabricated on glass slide, using a spin-coating method. To confirm that each aptamers retained its specific binding activities to their antigenic live bacteria, microscopic view of bound cells immobilized on silver film were observed. Furthermore, we observed the fluorescence-emitting bacteria-aptamer complex immobilized on silver film after adding RNA aptamers hybridized with fluorophore, FAM-conjugated 16 dT-linker molecules. As a result, the RNA aptamers-immobilized slide system developed in this study was a useful new tool to rapidly monitor individual food pathogens.

Influence of thiol capping on the photoluminescence properties of L-cysteine-, mercaptoethanol- and mercaptopropionic acid-capped ZnS nanoparticles.

PubMed

Tiwari, A; Dhoble, S J; Kher, R S

2015-11-01

Mercaptoethanol (ME), mercaptopropionic acid (MPA) and L-cysteine (L-Cys) having -SH functional groups were used as surface passivating agents for the wet chemical synthesis of ZnS nanoparticles. The effect of the thiol group on the optical and photoluminescence (PL) properties of ZnS nanoparticles was studied. L-Cysteine-capped ZnS nanoparticles showed the highest PL intensity among the studied capping agents, with a PL emission peak at 455 nm. The PL intensity was found to be dependent on the concentration of Zn(2+) and S(2-) precursors. The effect of buffer on the PL intensity of L-Cys-capped ZnS nanoparticles was also studied. UV/Vis spectra showed blue shifting of the absorption edge. Copyright © 2015 John Wiley & Sons, Ltd.

Selective redox regulation of cytokine receptor signaling by extracellular thioredoxin-1

PubMed Central

Schwertassek, Ulla; Balmer, Yves; Gutscher, Marcus; Weingarten, Lars; Preuss, Marc; Engelhard, Johanna; Winkler, Monique; Dick, Tobias P

2007-01-01

The thiol-disulfide oxidoreductase thioredoxin-1 (Trx1) is known to be secreted by leukocytes and to exhibit cytokine-like properties. Extracellular effects of Trx1 require a functional active site, suggesting a redox-based mechanism of action. However, specific cell surface proteins and pathways coupling extracellular Trx1 redox activity to cellular responses have not been identified so far. Using a mechanism-based kinetic trapping technique to identify disulfide exchange interactions on the intact surface of living lymphocytes, we found that Trx1 catalytically interacts with a single principal target protein. This target protein was identified as the tumor necrosis factor receptor superfamily member 8 (TNFRSF8/CD30). We demonstrate that the redox interaction is highly specific for both Trx1 and CD30 and that the redox state of CD30 determines its ability to engage the cognate ligand and transduce signals. Furthermore, we confirm that Trx1 affects CD30-dependent changes in lymphocyte effector function. Thus, we conclude that receptor–ligand signaling interactions can be selectively regulated by an extracellular redox catalyst. PMID:17557078

Reversible inactivation of CO dehydrogenase with thiol compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreß, Oliver; Gnida, Manuel; Pelzmann, Astrid M.

2014-05-09

Highlights: • Rather large thiols (e.g. coenzyme A) can reach the active site of CO dehydrogenase. • CO- and H{sub 2}-oxidizing activity of CO dehydrogenase is inhibited by thiols. • Inhibition by thiols was reversed by CO or upon lowering the thiol concentration. • Thiols coordinate the Cu ion in the [CuSMo(=O)OH] active site as a third ligand. - Abstract: Carbon monoxide dehydrogenase (CO dehydrogenase) from Oligotropha carboxidovorans is a structurally characterized member of the molybdenum hydroxylase enzyme family. It catalyzes the oxidation of CO (CO + H{sub 2}O → CO{sub 2} + 2e{sup −} + 2H{sup +}) which proceedsmore » at a unique [CuSMo(=O)OH] metal cluster. Because of changing activities of CO dehydrogenase, particularly in subcellular fractions, we speculated whether the enzyme would be subject to regulation by thiols (RSH). Here we establish inhibition of CO dehydrogenase by thiols and report the corresponding K{sub i}-values (mM): L-cysteine (5.2), D-cysteine (9.7), N-acetyl-L-cysteine (8.2), D,L-homocysteine (25.8), L-cysteine–glycine (2.0), dithiothreitol (4.1), coenzyme A (8.3), and 2-mercaptoethanol (9.3). Inhibition of the enzyme was reversed by CO or upon lowering the thiol concentration. Electron paramagnetic resonance spectroscopy (EPR) and X-ray absorption spectroscopy (XAS) of thiol-inhibited CO dehydrogenase revealed a bimetallic site in which the RSH coordinates to the Cu-ion as a third ligand ([Mo{sup VI}(=O)OH{sub (2)}SCu{sup I}(SR)S-Cys]) leaving the redox state of the Cu(I) and the Mo(VI) unchanged. Collectively, our findings establish a regulation of CO dehydrogenase activity by thiols in vitro. They also corroborate the hypothesis that CO interacts with the Cu-ion first. The result that thiol compounds much larger than CO can freely travel through the substrate channel leading to the bimetallic cluster challenges previous concepts involving chaperone function and is of importance for an understanding how the sulfuration step in the assembly of the bimetallic cluster might proceed.« less

Stable engineered vascular networks from human induced pluripotent stem cell-derived endothelial cells cultured in synthetic hydrogels

PubMed Central

Zanotelli, Matthew R.; Ardalani, Hamisha; Zhang, Jue; Hou, Zhonggang; Nguyen, Eric H.; Swanson, Scott; Nguyen, Bao Kim; Bolin, Jennifer; Elwell, Angela; Bischel, Lauren L.; Xie, Angela W.; Stewart, Ron; Beebe, David J.; Thomson, James A.; Schwartz, Michael P.; Murphy, William L.

2016-01-01

Here, we describe an in vitro strategy to model vascular morphogenesis where human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) are encapsulated in peptide-functionalized poly(ethylene glycol) (PEG) hydrogels, either on standard well plates or within a passive pumping polydimethylsiloxane (PDMS) tri-channel microfluidic device. PEG hydrogels permissive towards cellular remodeling were fabricated using thiol-ene photopolymerization to incorporate matrix metalloproteinase (MMP)-degradable crosslinks and CRGDS cell adhesion peptide. Time lapse microscopy, immunofluorescence imaging, and RNA sequencing (RNA-Seq) demonstrated that iPSC-ECs formed vascular networks through mechanisms that were consistent with in vivo vasculogenesis and angiogenesis when cultured in PEG hydrogels. Migrating iPSC-ECs condensed into clusters, elongated into tubules, and formed polygonal networks through sprouting. Genes upregulated for iPSC-ECs cultured in PEG hydrogels relative to control cells on tissue culture polystyrene (TCP) surfaces included adhesion, matrix remodeling, and Notch signaling pathway genes relevant to in vivo vascular development. Vascular networks with lumens were stable for at least 14 days when iPSC-ECs were encapsulated in PEG hydrogels that were polymerized within the central channel of the microfluidic device. Therefore, iPSC-ECs cultured in peptide-functionalized PEG hydrogels offer a defined platform for investigating vascular morphogenesis in vitro using both standard and microfluidic formats. PMID:26945632

Recycling of the High Valence States of Heme Proteins by Cysteine Residues of Thimet-Oligopeptidase

PubMed Central

Ferreira, Juliana C.; Icimoto, Marcelo Y.; Marcondes, Marcelo F.; Oliveira, Vitor; Nascimento, Otaciro R.; Nantes, Iseli L.

2013-01-01

The peptidolytic enzyme THIMET-oligopeptidase (TOP) is able to act as a reducing agent in the peroxidase cycle of myoglobin (Mb) and horseradish peroxidase (HRP). The TOP-promoted recycling of the high valence states of the peroxidases to the respective resting form was accompanied by a significant decrease in the thiol content of the peptidolytic enzyme. EPR (electron paramagnetic resonance) analysis using DBNBS spin trapping revealed that TOP also prevented the formation of tryptophanyl radical in Mb challenged by H2O2. The oxidation of TOP thiol groups by peroxidases did not promote the inactivating oligomerization observed in the oxidation promoted by the enzyme aging. These findings are discussed towards a possible occurrence of these reactions in cells. PMID:24223886

An oxidative cross-coupling reaction of 4-hydroxydithiocoumarin and amines/thiols using a combination of I2 and TBHP: access to lead molecules for biomedical applications.

PubMed

Mahato, Karuna; Arora, Neha; Ray Bagdi, Prasanta; Gattu, Radhakrishna; Ghosh, Siddhartha Sankar; Khan, Abu T

2018-02-06

A metal-free I 2 /TBHP induced highly atom economic and operationally simple oxidative cross-coupling reaction has been developed for the direct synthesis of sulfenamides/sulfanes/disulfides from the reaction of 4-hydroxydithiocoumarin and amines/thiols. The novelties of the present protocol are unprecedented S-C bond formation in addition to S-N and S-S bonds, shorter reaction time, mild and environmentally benign reaction conditions, functional group tolerance and moderate to excellent yields. Moreover, the four newly synthesized compounds namely 4q, 6d, 6e and 7a exhibit anti-proliferative activity against the breast cancer cell line MCF7, and may be lead molecules for future drug development.

Photolithography of Dithiocarbamate-Anchored Monolayers and Polymers on Gold

PubMed Central

Leonov, Alexei P.; Wei, Alexander

2011-01-01

Dithiocarbamate (DTC)-anchored monolayers and polymers were investigated as positive resists for UV photolithography on planar and roughened Au surfaces. DTCs were formed in situ by the condensation of CS2 with monovalent or polyvalent amines such as linear polyethyleneimine (PEI) under mildly basic aqueous conditions, just prior to surface passivation. The robust adsorption of the polyvalent PEI-DTC to Au surfaces supported high levels of resistance to photoablation, providing opportunities to generate thin films with gradient functionality. Treatment of photopatterned substrates with alkanethiols produced binary coatings, enabling a direct visual comparison of DTC- and thiol-passivated surfaces against chemically induced corrosion using confocal microscopy. PMID:21894240

Germanium oxide removal by citric acid and thiol passivation from citric acid-terminated Ge(100).

PubMed

Collins, Gillian; Aureau, Damien; Holmes, Justin D; Etcheberry, Arnaud; O'Dwyer, Colm

2014-12-02

Many applications of germanium (Ge) are underpinned by effective oxide removal and surface passivation. This important surface treatment step often requires H-X (X = Cl, Br, I) or HF etchants. Here, we show that aqueous citric acid solutions are effective in the removal of GeOx. The stability of citric acid-treated Ge(100) is compared to HF and HCl treated surfaces and analyzed by X-ray photoelectron spectroscopy. Further Ge surface passivation was investigated by thiolation using alkane monothiols and dithiols. The organic passivation layers show good stability with no oxide regrowth observed after 3 days of ambient exposure.

Sensitive determination of thiols in wine samples by a stable isotope-coded derivatization reagent d0/d4-acridone-10-ethyl-N-maleimide coupled with high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis.

PubMed

Lv, Zhengxian; You, Jinmao; Lu, Shuaimin; Sun, Weidi; Ji, Zhongyin; Sun, Zhiwei; Song, Cuihua; Chen, Guang; Li, Guoliang; Hu, Na; Zhou, Wu; Suo, Yourui

2017-03-31

As the key aroma compounds, varietal thiols are the crucial odorants responsible for the flavor of wines. Quantitative analysis of thiols can provide crucial information for the aroma profiles of different wine styles. In this study, a rapid and sensitive method for the simultaneous determination of six thiols in wine using d 0 /d 4 -acridone-10-ethyl-N-maleimide (d 0 /d 4 -AENM) as stable isotope-coded derivatization reagent (SICD) by high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) has been developed. Quantification of thiols was performed by using d 4 -AENM labeled thiols as the internal standards (IS), followed by stable isotope dilution HPLC-ESI-MS/MS analysis. The AENM derivatization combined with multiple reactions monitoring (MRM) not only allowed trace analysis of thiols due to the extremely high sensitivity, but also efficiently corrected the matrix effects during HPLC-MS/MS and the fluctuation in MS/MS signal intensity due to instrument. The obtained internal standard calibration curves for six thiols were linear over the range of 25-10,000pmol/L (R 2 ≥0.9961). Detection limits (LODs) for most of analytes were below 6.3pmol/L. The proposed method was successfully applied for the simultaneous determination of six kinds of thiols in wine samples with precisions ≤3.5% and recoveries ≥78.1%. In conclusion, the developed method is expected to be a promising tool for detection of trace thiols in wine and also in other complex matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

A Study of Functional Polymer Colloids Prepared Using Thiol-Ene/Yne Click Chemistry

NASA Astrophysics Data System (ADS)

Durham, Olivia Z.

This project demonstrates the first instance of thiol-ene chemistry as the polymerization method for the production of polymer colloids in two-phase heterogeneous suspensions, miniemulsions, and emulsions. This work was also expanded to thiol-yne chemistry for the production of polymer particles containing increased crosslinking density. The utility of thiol-ene and thiol-yne chemistries for polymerization and polymer modification is well established in bulk systems. These reactions are considered 'click' reactions, which can be defined as processes that are both facile and simple, offering high yields with nearly 100% conversion, no side products, easy product separation, compatibility with a diverse variety of commercially available starting materials, and orthogonality with other chemistries. In addition, thiol-ene and thiol-yne chemistry follow a step-growth mechanism for the development of highly uniform polymer networks, where polymer growth is dependent on the coupling of functional groups. These step-growth polymerization systems are in stark contrast to the chain-growth mechanisms of acrylic and styrenic monomers that have dominated the field of conventional heterogeneous polymerizations. Preliminary studies evaluated the mechanism of particle production in suspension and miniemulsion systems. Monomer droplets were compared to the final polymer particles to confirm that particle growth occurred through the polymerization of monomer droplets. Additional parameters examined include homogenization energy (mechanical mixing), diluent species and concentration, and monomer content. These reactions were conducted using photoinitiation to yield particles in a matter of minutes with diameters in the size range of several microns to hundreds of microns in suspensions or submicron particles in miniemulsions. Improved control over the particle size and size distribution was examined through variation of reaction parameters. In addition, a method of seeded suspension polymerization was attempted. This project was further expanded through an extensive evaluation of stabilizers in thiol-ene suspension polymerizations. The scope of stabilizers used included synthetic surfactants (ionic and nonionic), natural gums, and colloidal silica (Pickering stabilization). Suspension polymerizations were further expanded to include thiol-yne chemistry for the evaluation of polymer composition and thermal properties. In addition, polymer particles with excess ene, yne, or thiol functionality were successfully developed to demonstrate the potential for further functionalization. The self-limiting behavior of thiol-ene/yne reactions allows for successful synthesis of functional polymer colloids using off-stoichiometric amounts of monomers. This capacity to control functionality is illustrated through the creation of fluorescent polymer particles using both an in situ thiol-ene polymerization reaction with a vinyl chromophore as well as through post-polymerization modification of thiol-ene and thiol-yne polymers with excess thiol functionality via thiol-isocyanate chemistry. To produce smaller polymer particles without the need for intense homogenization energy or high stabilizer concentrations, an emulsion polymerization system was implemented using a water soluble-thermal initiator. It was found that unlike thiol-ene suspensions, which are limited to crosslinked systems, thiol-ene emulsion polymerizations allowed for the production of polymer particles comprised of either crosslinked or linear polymer networks. For the crosslinked systems, various anionic SDS surfactant concentrations were examined to observe the influence on particle size. In linear polymer systems, variations in polymer composition were examined. Preliminary studies performed with a monomer with an ethylene glycol-like structure indicated that the synthesis of polymer particles with narrower size distributions compared to any of the other emulsion compositions was possible. Finally, thiol-ene chemistry was also employed toward the synthesis of degradable polyanhydride polymer particles. Unlike the aforementioned studies, the approach to particle synthesis was conducted by using a premade thiol-ene polymer. Various linear thiol-ene polyanhydrides were emulsified in water or buffered solutions via sonication. Polymer latex was obtained upon solvent evaporation of the dichloromethane (DCM) solvent used to solubilize the polymer. In this work, variation of polymer composition as well as degradation was examined. Additional experiments included a study of the release of Rhodamine B dye, functionalization of the linear polymers, and studies involving the delay of degradation through the incorporation of crosslinking in the polymer particles. The projects presented herein provide an innovative approach to the synthesis of polymer colloids using thiol-ene and thiol-yne 'click' chemistry in both heterogeneous polymerizations as well as through solvent evaporation of premade polymer solutions. Polymer colloids prove to be an area of great interest for numerous applications that encompass various areas involving biomedical and industrial technologies including paints and coatings, cosmetics, diagnostics, and drug delivery. Improvements in methods of chemical synthesis as well as advances in the tailoring of material properties are of utmost importance for the ever increasing demands of new technologies and educational enlightenment.

Precise engineering of siRNA delivery vehicles to tumors using polyion complexes and gold nanoparticles.

PubMed

Kim, Hyun Jin; Takemoto, Hiroyasu; Yi, Yu; Zheng, Meng; Maeda, Yoshinori; Chaya, Hiroyuki; Hayashi, Kotaro; Mi, Peng; Pittella, Frederico; Christie, R James; Toh, Kazuko; Matsumoto, Yu; Nishiyama, Nobuhiro; Miyata, Kanjiro; Kataoka, Kazunori

2014-09-23

For systemic delivery of siRNA to solid tumors, a size-regulated and reversibly stabilized nanoarchitecture was constructed by using a 20 kDa siRNA-loaded unimer polyion complex (uPIC) and 20 nm gold nanoparticle (AuNP). The uPIC was selectively prepared by charge-matched polyionic complexation of a poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) copolymer bearing ∼40 positive charges (and thiol group at the ω-end) with a single siRNA bearing 40 negative charges. The thiol group at the ω-end of PEG-PLL further enabled successful conjugation of the uPICs onto the single AuNP through coordinate bonding, generating a nanoarchitecture (uPIC-AuNP) with a size of 38 nm and a narrow size distribution. In contrast, mixing thiolated PEG-PLLs and AuNPs produced a large aggregate in the absence of siRNA, suggesting the essential role of the preformed uPIC in the formation of nanoarchitecture. The smart uPIC-AuNPs were stable in serum-containing media and more resistant against heparin-induced counter polyanion exchange, compared to uPICs alone. On the other hand, the treatment of uPIC-AuNPs with an intracellular concentration of glutathione substantially compromised their stability and triggered the release of siRNA, demonstrating the reversible stability of these nanoarchitectures relative to thiol exchange and negatively charged AuNP surface. The uPIC-AuNPs efficiently delivered siRNA into cultured cancer cells, facilitating significant sequence-specific gene silencing without cytotoxicity. Systemically administered uPIC-AuNPs showed appreciably longer blood circulation time compared to controls, i.e., bare AuNPs and uPICs, indicating that the conjugation of uPICs onto AuNP was crucial for enhancing blood circulation time. Finally, the uPIC-AuNPs efficiently accumulated in a subcutaneously inoculated luciferase-expressing cervical cancer (HeLa-Luc) model and achieved significant luciferase gene silencing in the tumor tissue. These results demonstrate the strong potential of uPIC-AuNP nanoarchitectures for systemic siRNA delivery to solid tumors.

Kinetic Resolution of sec-Thiols by Enantioselective Oxidation with Rationally Engineered 5-(Hydroxymethyl)furfural Oxidase.

PubMed

Pickl, Mathias; Swoboda, Alexander; Romero, Elvira; Winkler, Christoph K; Binda, Claudia; Mattevi, Andrea; Faber, Kurt; Fraaije, Marco W

2018-03-05

Various flavoprotein oxidases were recently shown to oxidize primary thiols. Herein, this reactivity is extended to sec-thiols by using structure-guided engineering of 5-(hydroxymethyl)furfural oxidase (HMFO). The variants obtained were employed for the oxidative kinetic resolution of racemic sec-thiols, thus yielding the corresponding thioketones and nonreacted R-configured thiols with excellent enantioselectivities (E≥200). The engineering strategy applied went beyond the classic approach of replacing bulky amino acid residues with smaller ones, as the active site was additionally enlarged by a newly introduced Thr residue. This residue established a hydrogen-bonding interaction with the substrates, as verified in the crystal structure of the variant. These strategies unlocked HMFO variants for the enantioselective oxidation of a range of sec-thiols. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Activation energy determinations suggest that thiols reverse autooxidation of tetrahydrobiopterin by a different mechanism than ascorbate.

PubMed

Valent, Sándor; Tóth, Miklós

2006-01-01

In neutral aqueous solutions tetrahydrobiopterin is oxidized by dioxygen in a reaction that is succinctly described as autooxidation. Ascorbate and thiols moderate this reaction by reversing the oxidative process. In the present study the effect of various thiols on the apparent Arrhenius activation energy of tetrahydrobiopterin autooxidation was characterized and compared to that of ascorbate determined previously. We observed that - in sharp contrast to ascorbate - the efficiency of thiols to protect tetrahydrobiopterin decreased with the elevation of temperature from 22 to 37 degrees C. Accordingly, the apparent Arrhenius activation energies (in kJ/mol) measured in the presence of thiols were consistently greater than the value determined with tetrahydrobiopterin alone (59.6 +/- 1.4) or in the presence of ascorbate (59.9 +/- 2.8). Thus, the energy values were 88.8+/-1.1 with glutathione, 87.6 +/- 2.1 with N-acetylcysteine, 79.2 +/- 1.6 with cysteine, 75.1 +/- 2.4 with dithiotreitol and 70.3 +/- 0.9 with homocysteine. Since thiols are as potent reducing agents as ascorbate, these findings suggest that thiols and ascorbate protect tetrahydrobiopterin from oxidation acting at different steps of the oxidation process. It is likely that thiols reduce quinoidal dihydrobiopterin, whereas ascorbate scavenges the trihydrobiopterin radical to tetrahydrobiopterin. Furthermore, the results indicate that thiols are excellent tools to protect tetrahydrobiopterin from autooxidative decomposition in laboratory experiments conducted at relatively low temperatures, whereas the protective effect diminishes at 37 degrees C, i.e. under physiological conditions.

Spectrophotometric Determination of Phenolic Antioxidants in the Presence of Thiols and Proteins

PubMed Central

Avan, Aslı Neslihan; Demirci Çekiç, Sema; Uzunboy, Seda; Apak, Reşat

2016-01-01

Development of easy, practical, and low-cost spectrophotometric methods is required for the selective determination of phenolic antioxidants in the presence of other similar substances. As electron transfer (ET)-based total antioxidant capacity (TAC) assays generally measure the reducing ability of antioxidant compounds, thiols and phenols cannot be differentiated since they are both responsive to the probe reagent. In this study, three of the most common TAC determination methods, namely cupric ion reducing antioxidant capacity (CUPRAC), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt/trolox equivalent antioxidant capacity (ABTS/TEAC), and ferric reducing antioxidant power (FRAP), were tested for the assay of phenolics in the presence of selected thiol and protein compounds. Although the FRAP method is almost non-responsive to thiol compounds individually, surprising overoxidations with large positive deviations from additivity were observed when using this method for (phenols + thiols) mixtures. Among the tested TAC methods, CUPRAC gave the most additive results for all studied (phenol + thiol) and (phenol + protein) mixtures with minimal relative error. As ABTS/TEAC and FRAP methods gave small and large deviations, respectively, from additivity of absorbances arising from these components in mixtures, mercury(II) compounds were added to stabilize the thiol components in the form of Hg(II)-thiol complexes so as to enable selective spectrophotometric determination of phenolic components. This error compensation was most efficient for the FRAP method in testing (thiols + phenols) mixtures. PMID:27529232

The change in serum Thiol/Disulphide homeostasis after transrectal ultrasound guided prostate biopsy

PubMed Central

Tokgöz, Hüsnü; Taş, Selim; Giray, Özlem; Yalçınkaya, Soner; Tokgöz, Özlem; Koca, Cemile; Savaş, Murat; Erel, Özcan

2017-01-01

ABSTRACT Objectives The aim of this prospective clinical study was to investigate variations in a novel oxidative stress marker (thiol/disulphide homeostasis) in men who underwent transrectal ultrasound guided prostate biopsy (TRUSB). Materials and Methods A total of 22 men undergoing TRUSB of the prostate were enrolled in the study. Patients with abnormal digital rectal examination and/or total prostate specific antigen (PSA) over 4ng/mL underwent TRUSB with 12 cores. Serum samples were obtained before and just after the procedure to evaluate the possible changes in thiol/disulphide homeostasis. Mean age, total PSA and free PSA, prostate volume and histopathological data were also recorded. Results Mean age of the study population was 65.05±8.89 years. Significant decreases in native and total thiol levels were documented after the biopsy procedure. However, serum disulphide levels and disulphide/native thiol, disulphide/total thiol and native/total thiol ratios did not significantly change after TRUSB. No correlation was observed between oxidative parameters and total PSA and free PSA levels, prostate volume and histopathology of the prostate. However, mean patient age was significantly correlated with mean native and total thiol levels. Conclusion Significant decreases in serum native and total thiol levels related to the prostate biopsy procedure suggest that TRUSB causes acute oxidative stress in the human body. Since our trial is the first in the current literature to investigate these oxidative stress markers in urology practice, additional studies are warranted. PMID:28128906

The change in serum Thiol/Disulphide homeostasis after transrectal ultrasound guided prostate biopsy.

PubMed

Tokgöz, Hüsnü; Taş, Selim; Giray, Özlem; Yalçınkaya, Soner; Tokgöz, Özlem; Koca, Cemile; Savaş, Murat; Erel, Özcan

2017-01-01

The aim of this prospective clinical study was to investigate variations in a novel oxidative stress marker (thiol/disulphide homeostasis) in men who underwent transrectal ultrasound guided prostate biopsy (TRUSB). A total of 22 men undergoing TRUSB of the prostate were enrolled in the study. Patients with abnormal digital rectal examination and/or total prostate specific antigen (PSA) over 4ng/mL underwent TRUSB with 12 cores. Serum samples were obtained before and just after the procedure to evaluate the possible changes in thiol/disulphide homeostasis. Mean age, total PSA and free PSA, prostate volume and histopathological data were also recorded. Mean age of the study population was 65.05±8.89 years. Significant decreases in native and total thiol levels were documented after the biopsy procedure. However, serum disulphide levels and disulphide/native thiol, disulphide/total thiol and native / total thiol ratios did not significantly change after TRUSB. No correlation was observed between oxidative parameters and total PSA and free PSA levels, prostate volume and histopathology of the prostate. However, mean patient age was significantly correlated with mean native and total thiol levels. Significant decreases in serum native and total thiol levels related to the prostate biopsy procedure suggest that TRUSB causes acute oxidative stress in the human body. Since our trial is the first in the current literature to investigate these oxidative stress markers in urology practice, additional studies are warranted. Copyright® by the International Brazilian Journal of Urology.

Assessment of oxidative stress markers and concentrations of selected elements in the leaves of Cassia occidentalis growing wild on a coal fly ash basin.

PubMed

Love, Amit; Banerjee, B D; Babu, C R

2013-08-01

Assessment of oxidative stress levels and tissue concentrations of elements in plants growing wild on fly ash basins is critical for realistic hazard identification of fly ash disposal areas. Hitherto, levels of oxidative stress markers in plants growing wild on fly ash basins have not been adequately investigated. We report here concentrations of selected metal and metalloid elements and levels of oxidative stress markers in leaves of Cassia occidentalis growing wild on a fly ash basin (Badarpur Thermal Power Station site) and a reference site (Garhi Mandu Van site). Plants growing on the fly ash basin had significantly high foliar concentration of As, Ni, Pb and Se and low foliar concentration of Mn and Fe compared to the plants growing on the reference site. The plants inhabiting the fly ash basin showed signs of oxidative stress and had elevated levels of lipid peroxidation, electrolyte leakage from cells and low levels of chlorophyll a and total carotenoids compared to plants growing at the reference site. The levels of both protein thiols and nonprotein thiols were elevated in plants growing on the fly ash basin compared to plants growing on the reference site. However, no differences were observed in the levels of cysteine, reduced glutathione and oxidized glutathione in plants growing at both the sites. Our study suggests that: (1) fly ash triggers oxidative stress responses in plants growing wild on fly ash basin, and (2) elevated levels of protein thiols and nonprotein thiols may have a role in protecting the plants from environmental stress.

Mechanism-based Proteomic Screening Identifies Targets of Thioredoxin-like Proteins*

PubMed Central

Nakao, Lia S.; Everley, Robert A.; Marino, Stefano M.; Lo, Sze M.; de Souza, Luiz E.; Gygi, Steven P.; Gladyshev, Vadim N.

2015-01-01

Thioredoxin (Trx)-fold proteins are protagonists of numerous cellular pathways that are subject to thiol-based redox control. The best characterized regulator of thiols in proteins is Trx1 itself, which together with thioredoxin reductase 1 (TR1) and peroxiredoxins (Prxs) comprises a key redox regulatory system in mammalian cells. However, there are numerous other Trx-like proteins, whose functions and redox interactors are unknown. It is also unclear if the principles of Trx1-based redox control apply to these proteins. Here, we employed a proteomic strategy to four Trx-like proteins containing CXXC motifs, namely Trx1, Rdx12, Trx-like protein 1 (Txnl1) and nucleoredoxin 1 (Nrx1), whose cellular targets were trapped in vivo using mutant Trx-like proteins, under conditions of low endogenous expression of these proteins. Prxs were detected as key redox targets of Trx1, but this approach also supported the detection of TR1, which is the Trx1 reductant, as well as mitochondrial intermembrane proteins AIF and Mia40. In addition, glutathione peroxidase 4 was found to be a Rdx12 redox target. In contrast, no redox targets of Txnl1 and Nrx1 could be detected, suggesting that their CXXC motifs do not engage in mixed disulfides with cellular proteins. For some Trx-like proteins, the method allowed distinguishing redox and non-redox interactions. Parallel, comparative analyses of multiple thiol oxidoreductases revealed differences in the functions of their CXXC motifs, providing important insights into thiol-based redox control of cellular processes. PMID:25561728