The pH sensitive properties of carboxymethyl chitosan nanoparticles cross-linked with calcium ions.

PubMed

Kalliola, Simo; Repo, Eveliina; Srivastava, Varsha; Heiskanen, Juha P; Sirviö, Juho Antti; Liimatainen, Henrikki; Sillanpää, Mika

2017-05-01

In environmental applications the applied materials are required to be non-toxic and biodegradable. Carboxymethyl chitosan nanoparticles cross-linked with Ca 2+ ions (CMC-Ca) fulfill these requirements, and they are also renewable. These nanoparticles were applied to oil-spill treatment in our previous study and here we focused on enhancing their properties. It was found that while the divalent Ca 2+ ions are crucial for the formation of the CMC-Ca, the attractive interaction between NH 3 + and COO - groups contributed significantly to the formation and stability of the CMC-Ca. The stability decreased as a function of pH due to the deprotonation of the amino groups. Therefore, the nanoparticles were found to be fundamentally pH sensitive in solution, if the pH deviated from the pH (7-9) that was used in the synthesis of the nanoparticles. The pH sensitive CMC-Ca synthesized in pH 7 and 8 were most stable in the studied conditions and could find applications in oil-spill treatment or controlled-release of substances. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Effect of curcumin caged silver nanoparticle on collagen stabilization for biomedical applications.

PubMed

Srivatsan, Kunnavakkam Vinjimur; Duraipandy, N; Begum, Shajitha; Lakra, Rachita; Ramamurthy, Usha; Korrapati, Purna Sai; Kiran, Manikantan Syamala

2015-04-01

The current study aims at understanding the influence of curcumin caged silver nanoparticle (CCSNP) on stability of collagen. The results indicated that curcumin caged silver nanoparticles efficiently stabilize collagen, indicated by enhanced tensile strength, fibril formation and viscosity. The tensile strength of curcumin caged silver nanoparticle cross-linked collagen and elongation at break was also found to be higher than glutaraldehyde cross-linked collagen. The physicochemical characteristics of curcumin caged nanoparticle cross-linked collagen exhibited enhanced strength. The thermal properties were also good with both thermal degradation temperature and hydrothermal stability higher than native collagen. CD analysis showed no structural disparity in spite of superior physicochemical properties suggesting the significance of curcumin caged nanoparticle mediated cross-linking. The additional enhancement in the stabilization of collagen could be attributed to multiple sites for interaction with collagen molecule provided by curcumin caged silver nanoparticles. The results of cell proliferation and anti-microbial activity assays indicated that curcumin caged silver nanoparticles promoted cell proliferation and inhibited microbial growth making it an excellent biomaterial for wound dressing application. The study opens scope for nano-biotechnological strategies for the development of alternate non-toxic cross-linking agents facilitating multiple site interaction thereby improving therapeutic values to the collagen for biomedical application. Copyright © 2015 Elsevier B.V. All rights reserved.

Spherical Nucleic Acids: A New Form of DNA

NASA Astrophysics Data System (ADS)

Cutler, Joshua Isaac

Spherical Nucleic Acids (SNAs) are a new class of nucleic acid-based nanomaterials that exhibit unique properties currently being explored in the contexts of gene-based cancer therapies and in the design of programmable nanoparticle-based materials. The properties of SNAs differ from canonical, linear nucleic acids by virtue of their dense packing into an oriented 3-dimensional array. SNAs can be synthesized from a number of useful nanoparticle templates, such as plasmonic gold and silver, magnetic oxides, luminescent semi-conductor quantum dots, and silica. In addition, by crosslinking the oligonucleotides and dissolving the core, they can be made in a hollow form as well. This dissertation describes the evolution of SNAs from initial studies of inorganic nanoparticle-based materials densely functionalized with oligonucleotides to the proving of a hypothesis that their unique properties can be observed in a core-less structure if the nucleic acids are densely packed and highly oriented. Chapter two describes the synthesis of densely functionalized polyvalent oligonucleotide superparamagnetic iron oxide nanoparticles using the copper-catalyzed azide-alkyne cycloaddition reaction. These particles are shown to exhibit cooperative binding in a density- and salt concentration-dependent fashion, with nearly identical behaviors to those of SNA-functionalized gold nanoparticles. Importantly, these particles are the first non-gold particles shown to be capable of entering cells in high numbers via the SNA-mediated cellular uptake pathway, and provided the first evidence that SNA-mediated cellular uptake is core-independent. In the third chapter, a gold nanoparticle catalyzed alkyne cross-linking reaction is described that is capable of forming hollow organic nanoparticles using polymers with alkyne-functionalized backbones. With this method, the alkyne-modified polymers adsorb to the particle surfaces, cross-link on the surface, allowing the gold nanoparticle to be subsequently dissolved oxidatively with KCN or Iodine. The reaction pathway is analyzed through characterization of the reaction progression and resulting products, and a mechanistic pathway is proposed. This is the first report of a gold nanoparticle catalyzed reaction involving the conversion of propargyl ethers to terminal alcohols, which can subsequently cross-link if densely arranged on a gold nanoparticle surface. Importantly, these structures can be synthesized using gold nanoparticles of a range of sizes, thereby providing control over the size and properties of the resulting crosslinked particle. Chapter four returns to the topic of SNAs and builds upon the chemistry of chapter three culminating in the synthesis of cross-linked hollow SNA nanoparticles. These structures are formed by the cross-linking of synthetically modified alkyne-bearing oligonucleotides through the pathway described in chapter three. When the gold core is dissolved, the resulting hollow SNAs exhibit nearly identical binding, nuclease resistance, cellular uptake, and gene regulation properties of SNA-gold nanoparticle conjugates. Indeed, this chapter demonstrates that the unique properties of SNA-nanoparticle conjugates are core-independent and stem solely from the dense ensemble of oligonucleotides arranged on their surfaces. The fifth chapter further asserts the synthetic achievements made in chapter four by showing how hollow SNAs can be substituted for SNA-gold nanoparticles in the context of DNA-programmable assembly. In this case, they can be used as building blocks within binary synthetic schemes to synthesize unique nanoparticle superlattices. It bolsters the design rules of DNA-programmable assembly by showing that the predicted structures form based on the behavior of SNA hybridization, and are universal for any SNA-functionalized nanoparticle.

Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

DOE PAGES

Bocharova, Vera; Sharp, Danna; Jones, Aaron; ...

2015-03-09

Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radiimore » in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.« less

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

NASA Astrophysics Data System (ADS)

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J.; Piletsky, Sergey

2016-11-01

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format.

PubMed

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J; Piletsky, Sergey

2016-11-24

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

PubMed Central

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J.; Piletsky, Sergey

2016-01-01

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays. PMID:27883023

DNA-guided nanoparticle assemblies

DOEpatents

Gang, Oleg; Nykypanchuk, Dmytro; Maye, Mathew; van der Lelie, Daniel

2013-07-16

In some embodiments, DNA-capped nanoparticles are used to define a degree of crystalline order in assemblies thereof. In some embodiments, thermodynamically reversible and stable body-centered cubic (bcc) structures, with particles occupying <.about.10% of the unit cell, are formed. Designs and pathways amenable to the crystallization of particle assemblies are identified. In some embodiments, a plasmonic crystal is provided. In some aspects, a method for controlling the properties of particle assemblages is provided. In some embodiments a catalyst is formed from nanoparticles linked by nucleic acid sequences and forming an open crystal structure with catalytically active agents attached to the crystal on its surface or in interstices.

Thiol-Reactive Star Polymers Display Enhanced Association with Distinct Human Blood Components.

PubMed

Glass, Joshua J; Li, Yang; De Rose, Robert; Johnston, Angus P R; Czuba, Ewa I; Khor, Song Yang; Quinn, John F; Whittaker, Michael R; Davis, Thomas P; Kent, Stephen J

2017-04-12

Directing nanoparticles to specific cell types using nonantibody-based methods is of increasing interest. Thiol-reactive nanoparticles can enhance the efficiency of cargo delivery into specific cells through interactions with cell-surface proteins. However, studies to date using this technique have been largely limited to immortalized cell lines or rodents, and the utility of this technology on primary human cells is unknown. Herein, we used RAFT polymerization to prepare pyridyl disulfide (PDS)-functionalized star polymers with a methoxy-poly(ethylene glycol) brush corona and a fluorescently labeled cross-linked core using an arm-first method. PDS star polymers were examined for their interaction with primary human blood components: six separate white blood cell subsets, as well as red blood cells and platelets. Compared with control star polymers, thiol-reactive nanoparticles displayed enhanced association with white blood cells at 37 °C, particularly the phagocytic monocyte, granulocyte, and dendritic cell subsets. Platelets associated with more PDS than control nanoparticles at both 37 °C and on ice, but they were not activated in the duration examined. Association with red blood cells was minor but still enhanced with PDS nanoparticles. Thiol-reactive nanoparticles represent a useful strategy to target primary human immune cell subsets for improved nanoparticle delivery.

Fabrication and biological imaging of polyhedral oligomeric silsesquioxane cross-linked fluorescent polymeric nanoparticles with aggregation-induced emission feature

NASA Astrophysics Data System (ADS)

Mao, Liucheng; Liu, Meiying; Xu, Dazhuang; Wan, Qing; Huang, Qiang; Jiang, Ruming; Shi, Yingge; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

2017-11-01

Aggregation-induced emission (AIE) dyes based fluorescent polymeric nanoparticles (FNPs) have been intensively explored for biomedical applications. However, many of these AIE-active FNPs are relied on the self-assembly of amphiphilic copolymers, which are not stable in diluted solution. Therefore, the introduction of cross-linkages into these micelles has demonstrated to be an efficient route to overcome this stability problem and endow ultra-low critical micelle concentrations (CMC) of these AIE-active FNPs. In this work, we reported the fabrication of cross-linked AIE-active FNPs through controllable reversible addition fragmentation chain transfer polymerization by using commercially available octavinyl-T8-silsesquioxane (8-vinyl POSS) as the cross-linkage for the first time. The resultant cross-linked amphiphilic copolymers (named as PEG-POSS-PhE) are prone to self-assemble into stable core-shell nanoparticles with well water dispersity, strong red fluorescence and low CMC (0.0069 mg mL-1) in aqueous solution. More importantly, PEG-POSS-PhE FNPs possess some other properties such as high water dispersity, uniform morphology and small size, excellent biocompatibility and cellular internalization, providing great potential of PEG-POSS-PhE FNPs for biological imaging application.

Aggregated silver nanoparticles based surface-enhanced Raman scattering enzyme-linked immunosorbent assay for ultrasensitive detection of protein biomarkers and small molecules.

PubMed

Liang, Jiajie; Liu, Hongwu; Huang, Caihong; Yao, Cuize; Fu, Qiangqiang; Li, Xiuqing; Cao, Donglin; Luo, Zhi; Tang, Yong

2015-06-02

Lowering the detection limit is critical to the design of bioassays required for medical diagnostics, environmental monitoring, and food safety regulations. The current sensitivity of standard color-based analyte detection limits the further use of enzyme-linked immunosorbent assays (ELISAs) in research and clinical diagnoses. Here, we demonstrate a novel method that uses the Raman signal as the signal-generating system of an ELISA and combines surface-enhanced Raman scattering (SERS) with silver nanoparticles aggregation for ultrasensitive analyte detection. The enzyme label of the ELISA controls the dissolution of Raman reporter-labeled silver nanoparticles through hydrogen peroxide and generates a strong Raman signal when the analyte is present. Using this assay, prostate-specific antigen (PSA) and the adrenal stimulant ractopamine (Rac) were detected in whole serum and urine at the ultralow concentrations of 10(-9) and 10(-6) ng/mL, respectively. The methodology proposed here could potentially be applied to other molecules detection as well as PSA and Rac.

Silica-based mesoporous nanoparticles for controlled drug delivery

PubMed Central

Kwon, Sooyeon; Singh, Rajendra K; Perez, Roman A; Abou Neel, Ensanya A

2013-01-01

Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible drug carriers available in the market, which can deliver therapeutic agents to the target site in a controlled manner. Among the carriers developed thus far, mesoporous materials emerged as a promising candidate that can deliver a variety of drug molecules in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Currently, sol-gel-derived mesoporous silica nanoparticles in soft conditions are of main interest due to simplicity in production and modification and the capacity to maintain function of bioactive agents. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release. The properties of mesopores, including pore size and porosity as well as the surface properties, can be altered depending on additives used to fabricate mesoporous silica nanoparticles. Active surface enables functionalisation to modify surface properties and link therapeutic molecules. The tuneable mesopore structure and modifiable surface of mesoporous silica nanoparticle allow incorporation of various classes of drug molecules and controlled delivery to the target sites. This review aims to present the state of knowledge of currently available drug delivery system and identify properties of an ideal drug carrier for specific application, focusing on mesoporous silica nanoparticles. PMID:24020012

Environmental nanoparticles are significantly over-expressed in acute myeloid leukemia.

PubMed

Visani, G; Manti, A; Valentini, L; Canonico, B; Loscocco, F; Isidori, A; Gabucci, E; Gobbi, P; Montanari, S; Rocchi, M; Papa, S; Gatti, A M

2016-11-01

The increase in the incidence of acute myeloid leukemia (AML) may suggest a possible environmental etiology. PM2.5 was declared by IARC a Class I carcinogen. No report has focused on particulate environmental pollution together with AML. The study investigated the presence and composition of particulate matter in blood with a Scanning Electron Microscope coupled with an Energy Dispersive Spectroscope, a sensor capable of identifying the composition of foreign bodies. 38 peripheral blood samples, 19 AML cases and 19 healthy controls, were analyzed. A significant overload of particulate matter-derived nanoparticles linked or aggregated to blood components was found in AML patients, while almost absent in matched healthy controls. Two-tailed Student's t-test, MANOVA and Principal Component Analysis indicated that the total numbers of aggregates and particles were statistically different between cases and controls (MANOVA, P<0.001 and P=0.009 respectively). The particles detected showed to contain highly-reactive, non-biocompatible and non-biodegradable metals; in particular, micro- and nano-sized particles grouped in organic/inorganic clusters, with statistically higher frequency of a subgroup of elements in AML samples. The demonstration, for the first time, of an overload of nanoparticles linked to blood components in AML patients could be the basis for a possible, novel pathogenetic mechanism for AML development. Copyright © 2016 Elsevier Ltd. All rights reserved.

pH-responsive thiolated chitosan nanoparticles for oral low-molecular weight heparin delivery: in vitro and in vivo evaluation.

PubMed

Fan, Bo; Xing, Yang; Zheng, Ying; Sun, Chuan; Liang, Guixian

2016-01-01

The aim of present study was to investigate a pH-responsive and mucoadhesive nanoparticle system for oral bioavailability enhancement of low-molecular weight heparin (LMWH). The thioglycolic acid (TGA) was first covalently attached to chitosan (CS) with 396.97 ± 54.54 μmol thiol groups per gram of polymer and then the nanoparticles were prepared with thiolated chitosan (TCS) and pH-sensitive polymer hydroxypropyl methylcellulose phthalate (HPMCP) by ionic cross-linking method. The obtained nanoparticles were characterized for the shape, particle size, zeta potential, drug entrapment efficiency and loading capacity. In vitro results revealed the acid stability of pH-responsive nanoparticles, which had a significant control over LMWH release and could effectively protect entrapped drugs in simulated gastric conditions. By the attachment of the thiol ligand, an improvement of permeation-enhancing effect on freshly excised carp intestine (1.86-fold improvement) could be found. The mucoadhesive properties were evaluated using fluorescently labeled TCS or CS nanoparticles. As compared with the controls, a significant improvement of mucoadhesion on rat intestinal mucosa was observed in TCS/HPMCP nanoparticles via confocal laser scanning microscopy. The activated partial thromboplastin time (APTT) was significantly prolonged and an increase in the oral bioavailability of LMWH was turned out to be pronounced after oral delivered LMWH-loaded TCS/HPMCP nanoparticles in rats, which suggested enhanced anticoagulant effects and improved absorption of LMWH. In conclusion, pH-responsive TCS/HPMCP nanoparticles hold promise for oral delivery of LMWH.

Detection of Peptide-based nanoparticles in blood plasma by ELISA.

PubMed

Bode, Gerard H; Pickl, Karin E; Sanchez-Purrà, Maria; Albaiges, Berta; Borrós, Salvador; Pötgens, Andy J G; Schmitz, Christoph; Sinner, Frank M; Losen, Mario; Steinbusch, Harry W M; Frank, Hans-Georg; Martinez-Martinez, Pilar

2015-01-01

The aim of the current study was to develop a method to detect peptide-linked nanoparticles in blood plasma. A convenient enzyme linked immunosorbent assay (ELISA) was developed for the detection of peptides functionalized with biotin and fluorescein groups. As a proof of principle, polymerized pentafluorophenyl methacrylate nanoparticles linked to biotin-carboxyfluorescein labeled peptides were intravenously injected in Wistar rats. Serial blood plasma samples were analyzed by ELISA and by liquid chromatography mass spectrometry (LC/MS) technology. The ELISA based method for the detection of FITC labeled peptides had a detection limit of 1 ng/mL. We were able to accurately measure peptides bound to pentafluorophenyl methacrylate nanoparticles in blood plasma of rats, and similar results were obtained by LC/MS. We detected FITC-labeled peptides on pentafluorophenyl methacrylate nanoparticles after injection in vivo. This method can be extended to detect nanoparticles with different chemical compositions.

Detection of Peptide-Based Nanoparticles in Blood Plasma by ELISA

PubMed Central

Bode, Gerard H.; Pickl, Karin E.; Sanchez-Purrà, Maria; Albaiges, Berta; Borrós, Salvador; Pötgens, Andy J. G.; Schmitz, Christoph; Sinner, Frank M.; Losen, Mario; Steinbusch, Harry W. M.; Frank, Hans-Georg; Martinez-Martinez, Pilar

2015-01-01

Aims The aim of the current study was to develop a method to detect peptide-linked nanoparticles in blood plasma. Materials & Methods A convenient enzyme linked immunosorbent assay (ELISA) was developed for the detection of peptides functionalized with biotin and fluorescein groups. As a proof of principle, polymerized pentafluorophenyl methacrylate nanoparticles linked to biotin-carboxyfluorescein labeled peptides were intravenously injected in Wistar rats. Serial blood plasma samples were analyzed by ELISA and by liquid chromatography mass spectrometry (LC/MS) technology. Results The ELISA based method for the detection of FITC labeled peptides had a detection limit of 1 ng/mL. We were able to accurately measure peptides bound to pentafluorophenyl methacrylate nanoparticles in blood plasma of rats, and similar results were obtained by LC/MS. Conclusions We detected FITC-labeled peptides on pentafluorophenyl methacrylate nanoparticles after injection in vivo. This method can be extended to detect nanoparticles with different chemical compositions. PMID:25996618

β-cyclodextrin-poly(β-amino ester) nanoparticles for sustained drug delivery across the blood-brain barrier.

PubMed

Gil, Eun Seok; Wu, Linfeng; Xu, Lichong; Lowe, Tao Lu

2012-11-12

Novel biodegradable polymeric nanoparticles composed of β-cyclodextrin and poly(β-amino ester) segments have been developed for sustained drug delivery across the blood-brain barrier (BBB). The nanoparticles have been synthesized by cross-linking β-cyclodextrin with poly(β-amino ester) via the Michael addition method. The chemical, physical, and degradation properties of the nanoparticles have been characterized by matrix-assisted laser desoption/ionization time-of-flight, attenuated total reflectance Fourier transform infrared spectroscopy, nuclear magnetic resonance, dynamic light scattering, and atomic force microscopy techniques. Bovine and human brain microvascular endothelial cell monolayers have been constructed as in vitro BBB models. Preliminary results show that the nanoparticles do not affect the integrity of the in vitro BBB models, and the nanoparticles have much higher permeability than dextran control across the in vitro BBB models. Doxorubicin has been loaded into the nanoparticles with a loading efficiency of 86%, and can be released from the nanoparticles for at least one month. The developed β-cyclodextrin-poly(β-amino ester) nanoparticles might be useful as drug carriers for transporting drugs across the BBB to treat chronic diseases in the brain.

One-Pot Procedure for Recovery of Gallic Acid from Wastewater and Encapsulation within Protein Particles.

PubMed

Nourbakhsh, Himan; Madadlou, Ashkan; Emam-Djomeh, Zahra; Wang, Yi-Cheng; Gunasekaran, Sundaram; Mousavi, Mohammad E

2016-02-24

A whey protein isolate solution was heat-denatured and treated with the enzyme transglutaminase, which cross-linked ≈26% of the amino groups and increased the magnitude of the ζ-potential value. The protein solution was microemulsified, and then the resulting water-in-oil microemulsion was dispersed within a gallic acid-rich model wastewater. Gallic acid extraction by the outlined microemulsion liquid membrane (MLM) from the exterior aqueous phase (wastewater) and accumulation within the internal aqueous nanodroplets induced protein cold-set gelation and resulted in the formation of gallic acid-enveloping nanoparticles. Measurements with a strain-controlled rheometer indicated a progressive increase in the MLM viscosity during gallic acid recovery corresponding to particle formation. The mean hydrodynamic size of the nanoparticles made from the heat-denatured and preheated enzymatically cross-linked proteins was 137 and 122 nm, respectively. The enzymatic cross-linking of whey proteins led to a higher gallic acid recovery yield and increased the glass transition enthalpy and temperature. A similar impact on glass transition indices was observed by the gallic acid-induced nanoparticulation of proteins. Scanning electron microscopy showed the existence of numerous jammed/fused nanoparticles. It was suggested on the basis of the results of Fourier transform infrared spectroscopy that the in situ nanoparticulation of proteins shifted the C-N stretching and C-H bending peaks to higher wavenumbers. X-ray diffraction results proposed a decreased β-sheet content for proteins because of the acid-induced particulation. The nanoparticles made from the enzymatically cross-linked protein were more stable against the in vitro gastrointestinal digestion and retained almost 19% of the entrapped gallic acid after 300 min sequential gastric and intestinal digestions.

DNA-programmable nanoparticle crystallization.

PubMed

Park, Sung Yong; Lytton-Jean, Abigail K R; Lee, Byeongdu; Weigand, Steven; Schatz, George C; Mirkin, Chad A

2008-01-31

It was first shown more than ten years ago that DNA oligonucleotides can be attached to gold nanoparticles rationally to direct the formation of larger assemblies. Since then, oligonucleotide-functionalized nanoparticles have been developed into powerful diagnostic tools for nucleic acids and proteins, and into intracellular probes and gene regulators. In contrast, the conceptually simple yet powerful idea that functionalized nanoparticles might serve as basic building blocks that can be rationally assembled through programmable base-pairing interactions into highly ordered macroscopic materials remains poorly developed. So far, the approach has mainly resulted in polymerization, with modest control over the placement of, the periodicity in, and the distance between particles within the assembled material. That is, most of the materials obtained thus far are best classified as amorphous polymers, although a few examples of colloidal crystal formation exist. Here, we demonstrate that DNA can be used to control the crystallization of nanoparticle-oligonucleotide conjugates to the extent that different DNA sequences guide the assembly of the same type of inorganic nanoparticle into different crystalline states. We show that the choice of DNA sequences attached to the nanoparticle building blocks, the DNA linking molecules and the absence or presence of a non-bonding single-base flexor can be adjusted so that gold nanoparticles assemble into micrometre-sized face-centred-cubic or body-centred-cubic crystal structures. Our findings thus clearly demonstrate that synthetically programmable colloidal crystallization is possible, and that a single-component system can be directed to form different structures.

Colloidal polymers with controlled sequence and branching constructed from magnetic field assembled nanoparticles.

PubMed

Bannwarth, Markus B; Utech, Stefanie; Ebert, Sandro; Weitz, David A; Crespy, Daniel; Landfester, Katharina

2015-03-24

The assembly of nanoparticles into polymer-like architectures is challenging and usually requires highly defined colloidal building blocks. Here, we show that the broad size-distribution of a simple dispersion of magnetic nanocolloids can be exploited to obtain various polymer-like architectures. The particles are assembled under an external magnetic field and permanently linked by thermal sintering. The remarkable variety of polymer-analogue architectures that arises from this simple process ranges from statistical and block copolymer-like sequencing to branched chains and networks. This library of architectures can be realized by controlling the sequencing of the particles and the junction points via a size-dependent self-assembly of the single building blocks.

Dry powder inhaler formulation of lipid-polymer hybrid nanoparticles via electrostatically-driven nanoparticle assembly onto microscale carrier particles.

PubMed

Yang, Yue; Cheow, Wean Sin; Hadinoto, Kunn

2012-09-15

Lipid-polymer hybrid nanoparticles have emerged as promising nanoscale carriers of therapeutics as they combine the attractive characteristics of liposomes and polymers. Herein we develop dry powder inhaler (DPI) formulation of hybrid nanoparticles composed of poly(lactic-co-glycolic acid) and soybean lecithin as the polymer and lipid constituents, respectively. The hybrid nanoparticles are transformed into inhalable microscale nanocomposite structures by a novel technique based on electrostatically-driven adsorption of nanoparticles onto polysaccharide carrier particles, which eliminates the drawbacks of conventional techniques based on controlled drying (e.g. nanoparticle-specific formulation, low yield). First, we engineer polysaccharide carrier particles made up of chitosan cross-linked with tripolyphosphate and dextran sulphate to exhibit the desired aerosolization characteristics and physical robustness. Second, we investigate the effects of nanoparticle to carrier mass ratio and salt inclusion on the adsorption efficiency, in terms of the nanoparticle loading and yield, from which the optimal formulation is determined. Desorption of the nanoparticles from the carrier particles in phosphate buffer saline is also examined. Lastly, we characterize aerosolization efficiency of the nanocomposite product in vitro, where the emitted dose and respirable fraction are found to be comparable to the values of conventional DPI formulations. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and characterisation of cross-linked chitosan composites functionalised with silver and gold nanoparticles for antimicrobial applications

NASA Astrophysics Data System (ADS)

Ryan, Catherine; Alcock, Emma; Buttimer, Finbarr; Schmidt, Michael; Clarke, David; Pemble, Martyn; Bardosova, Maria

2017-12-01

We present a study of a range of cross-linked chitosan composites with potential antimicrobial applications. They were formed by cross-linking chitosan and siloxane networks and by introducing silver and gold nanoparticles (NPs). The aim was to investigate whether adding the metal NPs to the chitosan-siloxane composite would lead to a material with enhanced antimicrobial ability as compared to chitosan itself. The composites were synthesised in hydrogel form with the metal NPs embedded in the cross-linked chitosan network. Spectroscopic and microscopic techniques were employed to investigate the structural properties of the composite and the tensile strength of the structures was measured. It was found that the addition of metal NPs did not influence the mechanical strength of the composite. A crystal violet attachment assay results displayed a significant reduction in the attachment of E. coli to the cross-linked chitosan surfaces. Release profile tests suggest that the metal NPs do not contribute to the overall antimicrobial activity under neutral conditions. The contribution to the mechanical and antimicrobial properties from cross-linking with siloxane is significant, giving rise to a versatile, durable, antimicrobial material suitable for thin film formation, wound dressings or the coating of various surfaces where robustness and antimicrobial control are required.

Synthesis and characterisation of cross-linked chitosan composites functionalised with silver and gold nanoparticles for antimicrobial applications

PubMed Central

Ryan, Catherine; Alcock, Emma; Buttimer, Finbarr; Schmidt, Michael; Clarke, David; Pemble, Martyn; Bardosova, Maria

2017-01-01

Abstract We present a study of a range of cross-linked chitosan composites with potential antimicrobial applications. They were formed by cross-linking chitosan and siloxane networks and by introducing silver and gold nanoparticles (NPs). The aim was to investigate whether adding the metal NPs to the chitosan-siloxane composite would lead to a material with enhanced antimicrobial ability as compared to chitosan itself. The composites were synthesised in hydrogel form with the metal NPs embedded in the cross-linked chitosan network. Spectroscopic and microscopic techniques were employed to investigate the structural properties of the composite and the tensile strength of the structures was measured. It was found that the addition of metal NPs did not influence the mechanical strength of the composite. A crystal violet attachment assay results displayed a significant reduction in the attachment of E. coli to the cross-linked chitosan surfaces. Release profile tests suggest that the metal NPs do not contribute to the overall antimicrobial activity under neutral conditions. The contribution to the mechanical and antimicrobial properties from cross-linking with siloxane is significant, giving rise to a versatile, durable, antimicrobial material suitable for thin film formation, wound dressings or the coating of various surfaces where robustness and antimicrobial control are required. PMID:28804527

Synthesis and characterisation of cross-linked chitosan composites functionalised with silver and gold nanoparticles for antimicrobial applications.

PubMed

Ryan, Catherine; Alcock, Emma; Buttimer, Finbarr; Schmidt, Michael; Clarke, David; Pemble, Martyn; Bardosova, Maria

2017-01-01

We present a study of a range of cross-linked chitosan composites with potential antimicrobial applications. They were formed by cross-linking chitosan and siloxane networks and by introducing silver and gold nanoparticles (NPs). The aim was to investigate whether adding the metal NPs to the chitosan-siloxane composite would lead to a material with enhanced antimicrobial ability as compared to chitosan itself. The composites were synthesised in hydrogel form with the metal NPs embedded in the cross-linked chitosan network. Spectroscopic and microscopic techniques were employed to investigate the structural properties of the composite and the tensile strength of the structures was measured. It was found that the addition of metal NPs did not influence the mechanical strength of the composite. A crystal violet attachment assay results displayed a significant reduction in the attachment of E. coli to the cross-linked chitosan surfaces. Release profile tests suggest that the metal NPs do not contribute to the overall antimicrobial activity under neutral conditions. The contribution to the mechanical and antimicrobial properties from cross-linking with siloxane is significant, giving rise to a versatile, durable, antimicrobial material suitable for thin film formation, wound dressings or the coating of various surfaces where robustness and antimicrobial control are required.

Cellular membrane trafficking of mesoporous silica nanoparticles

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

Fang, I-Ju

This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulfmore » some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine the specific organelle that mesoporous silica nanoparticles could approach via the identification of harvested proteins from exocytosis process. Based on the study of endo- and exocytosis behavior of mesoporous silica nanoparticle materials, we can design smarter drug delivery vehicles for cancer therapy that can be effectively controlled. The destination, uptake efficiency and the cellular distribution of mesoporous silica nanoparticle materials can be programmable. As a result, release mechanism and release rate of drug delivery systems can be a well-controlled process. The deep investigation of an endo- and exocytosis study of mesoporous silica nanoparticle materials promotes the development of drug delivery applications.« less

Prolonged Hypocalcemic Effect by Pulmonary Delivery of Calcitonin Loaded Poly(Methyl Vinyl Ether Maleic Acid) Bioadhesive Nanoparticles

PubMed Central

Varshosaz, J.; Minaiyan, M.; Forghanian, M.

2014-01-01

The purpose of the present study was to design a pulmonary controlled release system of salmon calcitonin (sCT). Therefore, poly(methyl vinyl ether maleic acid) [P(MVEMA)] nanoparticles were prepared by ionic cross-linking method using Fe2+ and Zn2+ ions. Physicochemical properties of nanoparticles were studied in vitro. The stability of sCT in the optimized nanoparticles was studied by electrophoretic gel method. Plasma calcium levels until 48 h were determined in rats as pulmonary-free sCT solution or nanoparticles (25 μg·kg−1), iv solution of sCT (5 μg·kg−1), and pulmonary blank nanoparticles. The drug remained stable during fabrication and tests on nanoparticles. The optimized nanoparticles showed proper physicochemical properties. Normalized reduction of plasma calcium levels was at least 2.76 times higher in pulmonary sCT nanoparticles compared to free solution. The duration of hypocalcemic effect of pulmonary sCT nanoparticles was 24 h, while it was just 1 h for the iv solution. There was not any significant difference between normalized blood calcium levels reduction in pulmonary drug solution and iv injection. Pharmacological activity of nanoparticles after pulmonary delivery was 65% of the iv route. Pulmonary delivery of P(MVEMA) nanoparticles of sCT enhanced and prolonged the hypocalcemic effect of the drug significantly. PMID:24701588

SIRB, sans iron oxide rhodamine B, a novel cross-linked dextran nanoparticle, labels human neuroprogenitor and SH-SY5Y neuroblastoma cells and serves as a USPIO cell labeling control.

PubMed

Shen, Wei-Bin; Vaccaro, Dennis E; Fishman, Paul S; Groman, Ernest V; Yarowsky, Paul

2016-05-01

This is the first report of the synthesis of a new nanoparticle, sans iron oxide rhodamine B (SIRB), an example of a new class of nanoparticles. SIRB is designed to provide all of the cell labeling properties of the ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle Molday ION Rhodamine B (MIRB) without containing the iron oxide core. MIRB was developed to label cells and allow them to be tracked by MRI or to be manipulated by magnetic gradients. SIRB possesses a similar size, charge and cross-linked dextran coating as MIRB. Of great interest is understanding the biological and physiological changes in cells after they are labeled with a USPIO. Whether these effects are due to the iron oxide buried within the nanoparticle or to the surface coating surrounding the iron oxide core has not been considered previously. MIRB and SIRB represent an ideal pairing of nanoparticles to identify nanoparticle anatomy responsible for post-labeling cytotoxicity. Here we report the effects of SIRB labeling on the SH-SY5Y neuroblastoma cell line and primary human neuroprogenitor cells (hNPCs). These effects are contrasted with the effects of labeling SH-SY5Y cells and hNPCs with MIRB. We find that SIRB labeling, like MIRB labeling, (i) occurs without the use of transfection reagents, (ii) is packaged within lysosomes distributed within cell cytoplasm, (iii) is retained within cells with no loss of label after cell storage, and (iv) does not alter cellular viability or proliferation, and (v) SIRB labeled hNPCs differentiate normally into neurons or astrocytes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Diazonium salt-mediated synthesis of new amino, hydroxy, propargyl, and maleinimido-containing superparamagnetic Fe@C nanoparticles as platforms for linking bio-entities or organocatalytic moieties

NASA Astrophysics Data System (ADS)

Bunge, Alexander; Magerusan, Lidia; Morjan, Ion; Turcu, Rodica; Borodi, Gheorghe; Liebscher, Jürgen

2015-09-01

New magnetic Fe@C nanoparticles in the size range of about 20-50 nm functionalized with amino, hydroxy, propargyl, or maleinimido groups were synthesized by reaction with aryl diazonium salts. Aryl diazonium salts wherein the functional groups are linked via a sulfonamide moiety turned out to be advantageous over those with direct linkage. The obtained Fe@C nanoparticles represent magnetic nanoplatforms for linking bio-entities and organocatalysts using amide formation, CuAAC, or thiol-ene click chemistry as exemplified by selected examples. The Fe@C nanoparticles obtained exhibit supramolecular behavior with high value of saturation magnetization rendering them attractive for practical applications in biomedicine and organocatalysis.

Chitosan Nanoparticles Prepared by Ionotropic Gelation: An Overview of Recent Advances.

PubMed

Desai, Kashappa Goud

2016-01-01

The objective of this review is to summarize recent advances in chitosan nanoparticles prepared by ionotropic gelation. Significant progress has occurred in this area since the method was first reported. The gelation technique has been improved through a number of creative methodological modifications. Ionotropic gelation via electrospraying and spinning disc processing produces nanoparticles with a more uniform size distribution. Large-scale manufacturing of the nanoparticles can be achieved with the latter approach. Hydrophobic and hydrophilic drugs can be simultaneously encapsulated with high efficiency by emulsification followed by ionic gelation. The turbulent mixing approach facilitates nanoparticle formation at a relatively high polymer concentration (5 mg/mL). The technique can be easily tuned to achieve the desired polymer/surface modifications (e.g., blending, coating, and surface conjugation). Using factorial-design-based approaches, optimal conditions for nanoparticle formation can be determined with a minimum number of experiments. New insights have been gained into the mechanism of chitosan-tripolyphosphate nanoparticle formation. Chitosan nanoparticles prepared by ionotropic gelation tend to aggregate/agglomerate in unfavorable environments. Factors influencing this phenomenon and strategies that can be adopted to minimize the instability are discussed. Ionically cross-linked nanoparticles based on native chitosan and modified chitosan have shown excellent efficacy for controlled and targeted drug-delivery applications.

Large patternable metal nanoparticle sheets by photo/e-beam lithography

NASA Astrophysics Data System (ADS)

Saito, Noboru; Wang, Pangpang; Okamoto, Koichi; Ryuzaki, Sou; Tamada, Kaoru

2017-10-01

Techniques for micro/nano-scale patterning of large metal nanoparticle sheets can potentially be used to realize high-performance photoelectronic devices because the sheets provide greatly enhanced electrical fields around the nanoparticles due to localized surface plasmon resonances. However, no single metal nanoparticle sheet currently exists with sufficient durability for conventional lithographical processes. Here, we report large photo and/or e-beam lithographic patternable metal nanoparticle sheets with improved durability by incorporating molecular cross-linked structures between nanoparticles. The cross-linked structures were easily formed by a one-step chemical reaction; immersing a single nanoparticle sheet consisting of core metals, to which capping molecules ionically bond, in a dithiol ethanol solution. The ligand exchange reaction processes were discussed in detail, and we demonstrated 20 μm wide line and space patterns, and a 170 nm wide line of the silver nanoparticle sheets.

Control of DNA-Functionalized Nanoparticle Assembly

NASA Astrophysics Data System (ADS)

Olvera de La Cruz, Monica

Directed crystallization of a large variety of nanoparticles, including proteins, via DNA hybridization kinetics has led to unique materials with a broad range of crystal symmetries. The nanoparticles are functionalized with DNA chains that link neighboring functionalized units. The shape of the nanoparticle, the DNA length, the sequence of the hybridizing DNA linker and the grafting density determine the crystal symmetries and lattice spacing. By carefully selecting these parameters one can, in principle, achieve all the symmetries found for both atomic and colloidal crystals of asymmetric shapes as well as new symmetries, and drive transitions between them. A scale-accurate coarse-grained model with explicit DNA chains provides the design parameters, including degree of hybridization, to achieve specific crystal structures. The model also provides surface energy values to determine the shape of defect-free single crystals with macroscopic anisotropic properties, as well as the parameters to develop colloidal models that reproduce both the shape of single crystals and their growth kinetics.

Wrinkling of graphene membranes supported by silica nanoparticles on substrates

NASA Astrophysics Data System (ADS)

Yamamoto, Mahito; Cullen, William; Fuhrer, Michael; Einstein, Theodore; Department of Physics, University of Maryland Team

2011-03-01

The challenging endeavor of modulating the morphology of graphene via a patterned substrate to produce a controlled deformation has great potential importance for strain engineering the electronic properties of graphene. An essential step in this direction is to understand the response of graphene to substrate features of known geometry. Here we employ silica nanoparticles with a diameter of 10-100 nm to uniformly decorate Si O2 and mica substrates before depositing graphene, to promote nanoscale modulation of graphene geometry. The morphology of graphene on this modified substrate is then characterized by atomic force spectroscopy. We find that graphene on the substrate is locally raised by the supporting nanoparticles, and wrinkling propagates radially from the protrusions to form a ridge network which links the protrusions. We discuss the dependence of the wrinkled morphology on nanoparticle diameter and graphene thickness in terms of graphene elasticity and adhesion energy. Supported by NSF-MRSEC, Grant DMR 05-20471

The Chemical Composition and Structure of Supported Sulfated Zirconia with Regulated Size Nanoparticles

NASA Astrophysics Data System (ADS)

Kanazhevskiy, V. V.; Shmachkova, V. P.; Kotsarenko, N. S.; Kochubey, D. I.; Vedrine, J. C.

2007-02-01

A set of model skeletal isomerization catalysts — sulfated zirconia nanoparticles of controlled thickness anchored on different supports — was prepared using colloidal solutions of Zr salt on titania as support. The nanoparticles of zirconia (1-5 nm) are epitaxially connected to the support surface, with S/Zr ratio equals to 1.3-1.5. It was shown by EXAFS that nanoparticles of non-stoichiometric zirconium sulfate Zr(SO4)1+x, where x<0.5, are formed on the support surface. Its structure looks like half-period shifted counterdirected chains built-up by zirconium atoms linked by triangle pyramids of sulfate groups. Considering catalytic data of skeletal n-butane isomerisation at 150°C, one can suggest that these species behave as the active component of sulfated zirconia. They are formed in subsurface layers as zirconium hydroxide undergoes sulfation followed by thermal treatment.

The Self-Assembly of Nanogold for Optical Metamaterials

NASA Astrophysics Data System (ADS)

Nidetz, Robert A.

2011-12-01

Optical metamaterials are an emerging field that enables manipulation of light like never before. Producing optical metamaterials requires sub-wavelength building blocks. The focus here was to develop methods to produce building blocks for metamaterials from nanogold. Electron-beam lithography was used to define an aminosilane patterned chemical template in order to electrostatically self-assemble citrate-capped gold nanoparticles. Equilibrium self-assembly was achieved in 20 minutes by immersing chemical templates into gold nanoparticle solutions. The number of nanoparticles that self-assembled on an aminosilane dot was controlled by manipulating the diameters of the dots and nanoparticles. Adding salt to the nanoparticle solution enabled the nanoparticles to self-assemble in greater numbers on the same sized dot. However, the preparation of the nanoparticle solution containing salt was sensitive to spikes in the salt concentration which led to aggregation of the nanoparticles and non-specific deposition. Gold nanorods were also electrostatically self-assembled. Polyelectrolyte-coated gold nanorods were patterned with limited success. A polyelectrolyte chemical template also patterned gold nanorods, but the gold nanorods preferred to pattern on the edges of the pattern. Ligand-exchanged gold nanorods displayed the best self-assembly, but suffered from slow kinetics. Self-assembled gold nanoparticles were cross-linked with poly(diallyldimethylammonium chloride). The poly(diallyldimethylammonium chloride) allowed additional nanoparticles to pattern on top of the already patterned nanoparticles. Cross-linked nanoparticles were lifted-off of the substrate by sonication in a sodium hydroxide solution. The presence of van der Waals forces and/or amine bonding prevent the nanogold from lifting-off without sonication. A good-solvent evaporation process was used to self-assemble poly(styrene) coated gold nanoparticles into spherical microbead assemblies. The use of larger nanoparticles and larger poly(styrene) ligands resulted in larger and smaller assemblies, respectively. Stirring the solution resulted in a wider size distribution of microbead assemblies due to the stirring's shear forces. Two undeveloped methods to self-assemble nanogold were investigated. One method used block-copolymer thin films as chemical templates to direct the electrostatic self-assembly of nanogold. Another method used gold nanorods that are passivated with different ligands on different faces. The stability of an alkanethiol ligand in different acids and bases was investigated to determine which materials could be used to produce Janus nanorods.

Redox-Active Carbohydrate-Coated Nanoparticles: Self-Assembly of a Cyclodextrin-Polystyrene Glycopolymer with Tetrazine-Naphthalimide.

PubMed

Gross, Andrew J; Haddad, Raoudha; Travelet, Christophe; Reynaud, Eric; Audebert, Pierre; Borsali, Redouane; Cosnier, Serge

2016-11-15

The controlled self-assembly of precise and well-defined photochemically and electrochemically active carbohydrate-coated nanoparticles offers the exciting prospect of biocompatible catalysts for energy storage/conversion and biolabeling applications. Here an aqueous nanoparticle system has been developed with a versatile outer layer for host-guest molecule encapsulation via β-cyclodextrin inclusion complexes. A β-cyclodextrin-modified polystyrene polymer was first obtained by copper nanopowder click chemistry. The glycopolymer enables self-assembly and controlled encapsulation of tetrazine-naphthalimide, as a model redox-active agent, into nanoparticles via nanoprecipitation. Cyclodextrin host-guest interactions permit encapsulation and internanoparticle cross-linking for the formation of fluorescent compound and clustered self-assemblies with chemically reversible electroactivity in aqueous solution. Light scattering experiments revealed stable particles with hydrodynamic diameters of 138 and 654 nm for nanoparticles prepared with tetrazine, of which 95% of the nanoparticles represent the smaller objects by number. Dynamic light scattering revealed differences as a function of preparation method in terms of size, 3-month stability, polydispersity, radius of gyration, and shape factor. Individual self-assemblies were visualized by atomic force microscopy and fluorescence microscopy and monitored in real-time by nanoparticle tracking analysis. UV-vis and fluorescence spectra provided insight into the optical properties and critical evidence for host-guest encapsulation as evidenced by solvachromatism and enhanced tetrazine uptake. Cyclic voltammetry was used to investigate the electrochemical properties and provided further support for encapsulation and an estimate of the tetrazine loading capacity in tandem with light scattering data.

Molecularly-Targeted Gold-Based Nanoparticles for Cancer Imaging and Near-Infrared Photothermal Therapy

NASA Astrophysics Data System (ADS)

Day, Emily Shannon

2011-12-01

This thesis advances the use of nanoparticles as multifunctional agents for molecularly-targeted cancer imaging and photothermal therapy. Cancer mortality has remained relatively unchanged for several decades, indicating a significant need for improvements in care. Researchers are evaluating strategies incorporating nanoparticles as exogenous energy absorbers to deliver heat capable of inducing cell death selectively to tumors, sparing normal tissue. Molecular targeting of nanoparticles is predicted to improve photothermal therapy by enhancing tumor retention. This hypothesis is evaluated with two types of nanoparticles. The nanoparticles utilized, silica-gold nanoshells and gold-gold sulfide nanoparticles, can convert light energy into heat to damage cancerous cells. For in vivo applications nanoparticles are usually coated with poly(ethylene glycol) (PEG) to increase blood circulation time. Here, heterobifunctional PEG links nanoparticles to targeting agents (antibodies and growth factors) to provide cell-specific binding. This approach is evaluated through a series of experiments. In vitro, antibody-coated nanoparticles can bind breast carcinoma cells expressing the targeted receptor and act as contrast agents for multiphoton microscopy prior to inducing cell death via photoablation. Furthermore, antibody-coated nanoparticles can bind tissue ex vivo at levels corresponding to receptor expression, suggesting they should bind their target even in the complex biological milieu. This is evaluated by comparing the accumulation of antibody-coated and PEG-coated nanoparticles in subcutaneous glioma tumors in mice. Contrary to expectations, antibody targeting did not yield more nanoparticles within tumors. Nevertheless, these studies established the sensitivity of glioma to photothermal therapy; mice treated with PEG-coated nanoshells experienced 57% complete tumor regression versus no regression in control mice. Subsequent experiments employed intracranial tumors to better mimic the clinical setting. These tumors are highly vascularized, so nanoparticles were addressed toward receptors abundantly expressed on tumor vessels using growth factors as a novel targeting strategy. Photothermal therapy with these vascular-targeted nanoparticles disrupted tumor vessels, leading to a 2.2-fold prolongation of median survival versus control mice. This work confirms that nanoparticle surface coating can affect biodistribution and therapeutic efficacy. With continued optimization of molecular targeting strategies, imaging and photothermal therapy mediated by nanoshells and gold-gold sulfide nanoparticles may offer an effective alternative to conventional cancer management.

Enzymatically Controlled Vacancies in Nanoparticle Crystals

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

Barnaby, Stacey N.; Ross, Michael B.; Thaner, Ryan V.

In atomic systems, the mixing of metals results in distinct phase behavior that depends on the identity and bonding characteristics of the atoms. In nanoscale systems, the use of oligonucleotides as programmable “bonds” that link nanoparticle “atoms” into superlattices allows for the decoupling of atom identity and bonding. While much research in atomic systems is dedicated to understanding different phase behavior of mixed metals, it is not well understood on the nanoscale how changes in the nanoscale “bond” affect the phase behavior of nanoparticle crystals. In this work, the identity of the atom is kept the same but the chemicalmore » nature of the bond is altered, which is not possible in atomic systems, through the use of DNA and RNA bonding elements. These building blocks assemble into single crystal nanoparticle superlattices with mixed DNA and RNA bonding elements throughout. The nanoparticle crystals can be dynamically changed through the selective and enzymatic hydrolysis of the RNA bonding elements, resulting in superlattices that retain their crystalline structure and habit, while incorporating up to 35% random vacancies generated from the nanoparticles removed. Therefore, the bonding elements of nanoparticle crystals can be enzymatically and selectively addressed without affecting the nature of the atom.« less

Direct hierarchical assembly of nanoparticles

DOEpatents

Xu, Ting; Zhao, Yue; Thorkelsson, Kari

2014-07-22

The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

Fabrication of self-assembled (-)-epigallocatechin gallate (EGCG) ovalbumin-dextran conjugate nanoparticles and their transport across monolayers of human intestinal epithelial Caco-2 cells.

PubMed

Li, Zheng; Gu, Liwei

2014-02-12

Nanoparticles have the potential to increase bioavailability of nutraceutical compounds such as (-)-epigallocatechin gallate (EGCG). Ovalbumin was conjugated with dextran using the Maillard reaction. The resultant ovalbumin-dextran (O-D) conjugates were self-assembled with EGCG to form EGCG O-D conjugate nanoparticles at pH 5.2 after heating at 80 °C for 60 min. Ovalbumin in EGCG O-D conjugate nanoparticles was further cross-linked by glutaraldehyde for 24 h at room temperature. EGCG O-D conjugate nanoparticles and cross-linked EGCG O-D conjugate nanoparticles in aqueous suspension had particle sizes of 285 and 339 nm, respectively, and showed a spherical morphology. The loading efficiencies of EGCG in these two nanoparticles were 23.4 and 30.0%, whereas the loading capacities were 19.6 and 20.9%, respectively. These nanoparticles showed positive zeta-potentials in a pH range from 2.5 to 4.0 but had negative charges at pH ≥5.0. EGCG O-D conjugate nanoparticles maintained a particle size of 183-349 nm in simulated gastric fluid (SGF) and 188-291 nm in simulated intestinal fluid (SIF) at 37 °C for 2 h, whereas cross-linked nanoparticles had particle sizes of 294-527 nm in SGF and 206-300 nm in SIF. Limited release of EGCG was observed in both nanoparticle systems in simulated gastric and intestinal fluids without and with digestive enzymes. EGCG O-D conjugate nanoparticles significantly enhanced the apparent permeability coefficient (Papp) of EGCG on Caco-2 monolayers compared with EGCG solution, suggesting that these nanoparticles may improve the absorption of EGCG.

A new method for measuring lung deposition efficiency of airborne nanoparticles in a single breath

NASA Astrophysics Data System (ADS)

Jakobsson, Jonas K. F.; Hedlund, Johan; Kumlin, John; Wollmer, Per; Löndahl, Jakob

2016-11-01

Assessment of respiratory tract deposition of nanoparticles is a key link to understanding their health impacts. An instrument was developed to measure respiratory tract deposition of nanoparticles in a single breath. Monodisperse nanoparticles are generated, inhaled and sampled from a determined volumetric lung depth after a controlled residence time in the lung. The instrument was characterized for sensitivity to inter-subject variability, particle size (22, 50, 75 and 100 nm) and breath-holding time (3-20 s) in a group of seven healthy subjects. The measured particle recovery had an inter-subject variability 26-50 times larger than the measurement uncertainty and the results for various particle sizes and breath-holding times were in accordance with the theory for Brownian diffusion and values calculated from the Multiple-Path Particle Dosimetry model. The recovery was found to be determined by residence time and particle size, while respiratory flow-rate had minor importance in the studied range 1-10 L/s. The instrument will be used to investigate deposition of nanoparticles in patients with respiratory disease. The fast and precise measurement allows for both diagnostic applications, where the disease may be identified based on particle recovery, and for studies with controlled delivery of aerosol-based nanomedicine to specific regions of the lungs.

Comparison of cell uptake, biodistribution and tumor retention of folate-coated and PEG-coated gadolinium nanoparticles in tumor-bearing mice.

PubMed

Oyewumi, Moses O; Yokel, Robert A; Jay, Michael; Coakley, Tricia; Mumper, Russell J

2004-03-24

The purpose of these studies was to compare the cell uptake, biodistribution and tumor retention of folate-coated and PEG-coated gadolinium (Gd) nanoparticles. Gd is a potential agent for neutron capture therapy (NCT) of tumors. Gd nanoparticles were engineered from oil-in-water microemulsion templates. To obtain folate-coated nanoparticles, a folate ligand [folic acid chemically linked to distearoylphosphatidylethanolamine (DSPE) via a PEG spacer MW 3350] was included in nanoparticle preparations. Similarly, control nanoparticles were coated with DSPE-PEG-MW 3350 (PEG-coated). Nanoparticles were characterized based on size, size distribution, morphology, biocompatibility and tumor cell uptake. In vivo studies were carried out in KB (human nasopharyngeal carcinoma) tumor-bearing athymic mice. Biodistribution and tumor retention studies were carried out at pre-determined time intervals after injection of nanoparticles (10 mg/kg). Gd nanoparticles did not aggregate platelets or activate neutrophils. The retention of nanoparticles in the blood 8, 16 and 24 h post-injection was 60%, 13% and 11% of the injected dose (ID), respectively. A maximum Gd tumor localization of 33+/-7 microg Gd/g was achieved. Both folate-coated and PEG-coated nanoparticles had comparable tumor accumulation. However, the cell uptake and tumor retention of folate-coated nanoparticles was significantly enhanced over PEG-coated nanoparticles. Thus, the benefits of folate ligand coating were to facilitate tumor cell internalization and retention of Gd-nanoparticles in the tumor tissue. The engineered nanoparticles may have potential in tumor-targeted delivery of Gd thereby enhancing the therapeutic success of NCT.

One-pot synthesis of redox-responsive polymers-coated mesoporous silica nanoparticles and their controlled drug release.

PubMed

Sun, Jiao-Tong; Piao, Ji-Gang; Wang, Long-Hai; Javed, Mohsin; Hong, Chun-Yan; Pan, Cai-Yuan

2013-09-01

A versatile one-pot strategy for the preparation of reversibly cross-linked polymer-coated mesoporous silica nanoparticles (MSNs) via surface reversible addition-fragmentation chain transfer (RAFT) polymerization is presented for the first time in this paper. The less reactive monomer oligo(ethylene glycol) acrylate (OEGA) and the more reactive cross-linker N,N'-cystaminebismethacrylamide (CBMA) are chosen to be copolymerized on the external surfaces of RAFT agent-functionalized MSNs to form the cross-linked polymer shells. Owing to the reversible cleavage and restoration of disulfide bonds via reduction/oxidation reactions, the polymer shells can control the on/off switching of the nanopores and regulate the drug loading and release. The redox-responsive release of doxorubicin (DOX) from this drug carrier is realized. The protein adsorption, in vitro cytotoxicity assays, and endocytosis studies demonstrate that this biocompatible vehicle is a potential candidate for delivering drugs. It is expected that this versatile grafting strategy may help fabricate satisfying MSN-based drug delivery systems for clinical application. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Organically linked iron oxide nanoparticle supercrystals with exceptional isotropic mechanical properties.

PubMed

Dreyer, Axel; Feld, Artur; Kornowski, Andreas; Yilmaz, Ezgi D; Noei, Heshmat; Meyer, Andreas; Krekeler, Tobias; Jiao, Chengge; Stierle, Andreas; Abetz, Volker; Weller, Horst; Schneider, Gerold A

2016-05-01

It is commonly accepted that the combination of the anisotropic shape and nanoscale dimensions of the mineral constituents of natural biological composites underlies their superior mechanical properties when compared to those of their rather weak mineral and organic constituents. Here, we show that the self-assembly of nearly spherical iron oxide nanoparticles in supercrystals linked together by a thermally induced crosslinking reaction of oleic acid molecules leads to a nanocomposite with exceptional bending modulus of 114 GPa, hardness of up to 4 GPa and strength of up to 630 MPa. By using a nanomechanical model, we determined that these exceptional mechanical properties are dominated by the covalent backbone of the linked organic molecules. Because oleic acid has been broadly used as nanoparticle ligand, our crosslinking approach should be applicable to a large variety of nanoparticle systems.

Effect of amphiphilic polyurethane nanoparticles on sorption-desorption of phenanthrene in aquifer material.

PubMed

Kim, Ju-Young; Shim, Sun-Bo; Shim, Jin-Kie

2003-03-17

Micelle-like amphiphilic nano-sized polyurethane (APU) nanoparticles were synthesized via chemical cross-linking reaction of nano-aggregates of urethane acrylate nonionomer (UAN) chain and were tested for extraction efficiency of sorbed phenanthrene from aquifer material. Even though the solubilizing performance and interfacial activity of APU nanoparticles were inferior to that of Triton X-100, in the low concentration region, APU nanoparticles could effectively reduce phenanthrene sorption on the aquifer material and extracted sorbed phenanthrene from the aquifer material, whereas Triton X-100 could not extract sorbed phenanthrene and rather increased phenanthrene sorption onto the aquifer materials. At higher concentrations, APU nanoparticles and Triton X-100 had almost the same soil washing effectiveness. This interesting result is mainly due to a lower degree of sorption of APU nanoparticles onto the aquifer material. The sorption of APU nanoparticles onto aquifer sand is largely hindered by their chemically cross-linked nature, resulting in better soil-washing performance of APU nanoparticles than Triton X-100. Copyright 2003 Elsevier Science B.V.

Modeling the atomistic growth behavior of gold nanoparticles in solution

NASA Astrophysics Data System (ADS)

Turner, C. Heath; Lei, Yu; Bao, Yuping

2016-04-01

The properties of gold nanoparticles strongly depend on their three-dimensional atomic structure, leading to an increased emphasis on controlling and predicting nanoparticle structural evolution during the synthesis process. In order to provide this atomistic-level insight and establish a link to the experimentally-observed growth behavior, a kinetic Monte Carlo simulation (KMC) approach is developed for capturing Au nanoparticle growth characteristics. The advantage of this approach is that, compared to traditional molecular dynamics simulations, the atomistic nanoparticle structural evolution can be tracked on time scales that approach the actual experiments. This has enabled several different comparisons against experimental benchmarks, and it has helped transition the KMC simulations from a hypothetical toy model into a more experimentally-relevant test-bed. The model is initially parameterized by performing a series of automated comparisons of Au nanoparticle growth curves versus the experimental observations, and then the refined model allows for detailed structural analysis of the nanoparticle growth behavior. Although the Au nanoparticles are roughly spherical, the maximum/minimum dimensions deviate from the average by approximately 12.5%, which is consistent with the corresponding experiments. Also, a surface texture analysis highlights the changes in the surface structure as a function of time. While the nanoparticles show similar surface structures throughout the growth process, there can be some significant differences during the initial growth at different synthesis conditions.

Induced nanoparticle aggregation for short nucleic acid quantification by depletion isotachophoresis.

PubMed

Marczak, Steven; Senapati, Satyajyoti; Slouka, Zdenek; Chang, Hsueh-Chia

2016-12-15

A rapid (<20min) gel-membrane biochip platform for the detection and quantification of short nucleic acids is presented based on a sandwich assay with probe-functionalized gold nanoparticles and their separation into concentrated bands by depletion-generated gel isotachophoresis. The platform sequentially exploits the enrichment and depletion phenomena of an ion-selective cation-exchange membrane created under an applied electric field. Enrichment is used to concentrate the nanoparticles and targets at a localized position at the gel-membrane interface for rapid hybridization. The depletion generates an isotachophoretic zone without the need for different conductivity buffers, and is used to separate linked nanoparticles from isolated ones in the gel medium and then by field-enhanced aggregation of only the linked particles at the depletion front. The selective field-induced aggregation of the linked nanoparticles during the subsequent depletion step produces two lateral-flow like bands within 1cm for easy visualization and quantification as the aggregates have negligible electrophoretic mobility in the gel and the isolated nanoparticles are isotachophoretically packed against the migrating depletion front. The detection limit for 69-base single-stranded DNA targets is 10 pM (about 10 million copies for our sample volume) with high selectivity against nontargets and a three decade linear range for quantification. The selectivity and signal intensity are maintained in heterogeneous mixtures where the nontargets outnumber the targets 10,000 to 1. The selective field-induced aggregation of DNA-linked nanoparticles at the ion depletion front is attributed to their trailing position at the isotachophoretic front with a large field gradient. Copyright © 2016 Elsevier B.V. All rights reserved.

Live Cell Imaging of the Endocytosis and the Intracellular Trafficking of Multifunctional Lipid Nanoparticles

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

Zhang, Tieqiao; Danthi, S. N.; Xie, Jianwu

Artificial lipid nanoparticles have drawn great attention due to their potential in medicine. Linked with targeting ligands, they can be used as probes and/or gene delivery vectors for specific types of target cells. Therefore, they are very promising agents in early detection, diagnosis and treatment of cancers and other genetic diseases. However, there are several barriers blocking the applications. Controlling the cellular uptake of the lipid nanoparticles is an important technical challenge to overcome. Understanding the mechanism of the endocytosis and the following intracellular trafficking is very important for improving the design and therefore the efficiency as a drug deliverymore » system. By using fluorescence microscopy methods, we studied the endocytosis of lipid nanoparticles by live M21 cells. The movements of the nanoparticles inside the cell were quantitatively characterized and classified based on the diffusion behavior. The trajectories of nanoparticles movement over the cell membrane revealed hop-diffusion behavior prior to the endocytosis. Fast movement in large steps is observed in intracellular trafficking and is attributed to active movement along microtubule. These observations help to understand the mechanism of the endocytosis and the pathway of the particles in cells.« less

Live cell imaging of the endocytosis and the intracellular trafficking of multifunctional lipid nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Tieqiao; Danthi, S. Narasimhan; Xie, Jianwu; Hu, Dehong; Lu, Peter; Li, King

2006-02-01

Artificial lipid nanoparticles have drawn great attention due to their potential in medicine. Linked with targeting ligands, they can be used as probes and/or gene delivery vectors for specific types of target cells. Therefore, they are very promising agents in early detection, diagnosis and treatment of cancers and other genetic diseases. However, there are several barriers blocking the applications. Controlling the cellular uptake of the lipid nanoparticles is an important technical challenge to overcome. Understanding the mechanism of the endocytosis and the following intracellular trafficking is very important for improving the design and therefore the efficiency as a drug delivery system. By using fluorescence microscopy methods, we studied the endocytosis of lipid nanoparticles by live M21 cells. The movements of the nanoparticles inside the cell were quantitatively characterized and classified based on the diffusion behavior. The trajectories of nanoparticles movement over the cell membrane revealed hop-diffusion behavior prior to the endocytosis. Fast movement in large steps is observed in intracellular trafficking and is attributed to active movement along microtubule. These observations help to understand the mechanism of the endocytosis and the pathway of the particles in cells.

Nanoparticles as strengthening agents in polymer systems

NASA Astrophysics Data System (ADS)

Shahid, Naureen

2005-11-01

Carboxylate-substituted alumina nanoparticles are produced solvent free using mechanical shear. The general nature of this method has been demonstrated for L-lysine-, stearate, and p-hydroxybenzoate-derived materials. The reaction rate and particle size is controlled by a combination of temperature and shear rate. The nanoparticles are spectroscopically equivalent to those reported from aqueous syntheses, however, the average particle size can be decreased and the particle size distribution narrowed depending on the reaction conditions. Lysine and p-hydroxybenzoato alumoxanes have been introduced in carbon fiber reinforced epoxide resin composites. Different preparation conditions have been studied to obtain composite with enhanced performances that are ideal for the motor sports and aerospace industries. A new composite material has been fabricated utilizing surface-modified carboxylate alumoxane nanoparticles and the biodegradable polymer poly(propylene fumarate)/poly(propylene fumarate)-diacrylate (PPF/PPF-DA). For this study, composites were prepared using various functional groups including: a surfactant alumoxane to enhance nanoparticle dispersion into the polymer; an activated-alumoxane to enhance nanoparticle interaction with the polymer matrix; a mixed alumoxane containing both activated and surfactant groups. Nanocomposites prepared with all types of alumoxane, as well as blank polymer resin and unmodified boehmite, underwent mechanical testing and were characterized by SEM and microprobe analysis. A nanocomposite composed of mixed alumoxane nanoparticles dispersed in PPF/PPF-DA exhibited increased flexural modulus compared to polymer resin alone, and a significant enhancement over both the activated and surfacted alumoxanes. Boric acid is used as the cross-linking agent in oil well drilling industry even though the efficacy of the borate ion, [B(OH)4]- , as a cross-linking agent is poor. The reaction product of boric acid and the polysaccharide guaran (the major component of guar gum) has been investigated by 11B NMR spectroscopy. By comparison with the 11B NMR of boric acid and phenyl boronic acid complexes of 1,2-diols [HOCMe2CMe2OH, cis-C6H 10(OH)2, trans-C6H10(OH) 2, o-C6H4(OH)2], 1,3-diols (neol-H2), monosaccharides (L-fucose, mannose and galactose) and disaccharides (celloboise and sucrose) it is found that the guaran polymer is cross-linked via a borate complex of two 1,2-diols both forming chelate 5-membered ring cycles, this contrasts with previous proposals. (Abstract shortened by UMI.)

A new method for measuring lung deposition efficiency of airborne nanoparticles in a single breath

PubMed Central

Jakobsson, Jonas K. F.; Hedlund, Johan; Kumlin, John; Wollmer, Per; Löndahl, Jakob

2016-01-01

Assessment of respiratory tract deposition of nanoparticles is a key link to understanding their health impacts. An instrument was developed to measure respiratory tract deposition of nanoparticles in a single breath. Monodisperse nanoparticles are generated, inhaled and sampled from a determined volumetric lung depth after a controlled residence time in the lung. The instrument was characterized for sensitivity to inter-subject variability, particle size (22, 50, 75 and 100 nm) and breath-holding time (3–20 s) in a group of seven healthy subjects. The measured particle recovery had an inter-subject variability 26–50 times larger than the measurement uncertainty and the results for various particle sizes and breath-holding times were in accordance with the theory for Brownian diffusion and values calculated from the Multiple-Path Particle Dosimetry model. The recovery was found to be determined by residence time and particle size, while respiratory flow-rate had minor importance in the studied range 1–10 L/s. The instrument will be used to investigate deposition of nanoparticles in patients with respiratory disease. The fast and precise measurement allows for both diagnostic applications, where the disease may be identified based on particle recovery, and for studies with controlled delivery of aerosol-based nanomedicine to specific regions of the lungs. PMID:27819335

Thermomechanical Response of Self-Assembled Nanoparticle Membranes

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

Wang, Yifan; Chan, Henry; Narayanan, Badri

2017-07-21

Monolayers composed of colloidal nanoparticles, with a thickness of less than 10 nm, have remarkable mechanical moduli and can suspend over micrometer-sized holes to form free-standing membranes. In this paper, we discuss experiment's and coarse-grained molecular dynamics simulations characterizing the thermomechanical properties of these self-assembled nanoparticle membranes. These membranes remain strong and resilient up to temperatures much higher than previous simulation predictions and exhibit an unexpected hysteretic behavior during the first heating cooling cycle. We show this hysteretic behavior can be explained by an asymmetric ligand configuration from the self assembly process and can be controlled by changing the ligandmore » coverage or cross-linking the ligand molecules. Finally, we show the screening effect of water molecules on the ligand interactions can strongly affect the moduli and thermomechanical behavior.« less

Insight on the formation of chitosan nanoparticles through ionotropic gelation with tripolyphosphate.

PubMed

Koukaras, Emmanuel N; Papadimitriou, Sofia A; Bikiaris, Dimitrios N; Froudakis, George E

2012-10-01

This work reports details pertaining to the formation of chitosan nanoparticles that we prepare by the ionic gelation method. The molecular interactions of the ionic cross-linking of chitosan with tripolyphosphate have been investigated and elucidated by means of all-electron density functional theory. Solvent effects have been taken into account using implicit models. We have identified primary-interaction ionic cross-linking configurations that we define as H-link, T-link, and M-link, and we have quantified the corresponding interaction energies. H-links, which display high interaction energies and are also spatially broadly accessible, are the most probable cross-linking configurations. At close range, proton transfer has been identified, with maximum interaction energies ranging from 12.3 up to 68.3 kcal/mol depending on the protonation of the tripolyphosphate polyanion and the relative coordination of chitosan with tripolyphosphate. On the basis of our results for the linking types (interaction energies and torsion bias), we propose a simple mechanism for their impact on the chitosan/TPP nanoparticle formation process. We introduce the β ratio, which is derived from the commonly used α ratio but is more fundamental since it additionally takes into account structural details of the oligomers.

Smart surface coating of drug nanoparticles with cross-linkable polyethylene glycol for bio-responsive and highly efficient drug delivery.

PubMed

Wei, Weijia; Zhang, Xiujuan; Chen, Xianfeng; Zhou, Mengjiao; Xu, Ruirui; Zhang, Xiaohong

2016-04-21

Many drug molecules can be directly used as nanomedicine without the requirement of any inorganic or organic carriers such as silica and liposome nanostructures. This new type of carrier-free drug nanoparticles (NPs) has great potential in clinical treatment because of its ultra-high drug loading capacity and biodegradability. For practical applications, it is essential for such nanomedicine to possess robust stability and minimal premature release of therapeutic molecules during circulation in the blood stream. To meet this requirement, herein, we develop GSH-responsive and crosslinkable amphiphilic polyethylene glycol (PEG) molecules to modify carrier-free drug NPs. These PEG molecules can be cross-linked on the surface of the NPs to endow them with greater stability and the cross-link is sensitive to intracellular environment for bio-responsive drug release. With this elegant design, our experimental results show that the liberation of DOX from DOX-cross-linked PEG NPs is dramatically slower than that from DOX-non-cross-linked PEG NPs, and the DOX release profile can be controlled by tuning the concentration of the reducing agent to break the cross-link between PEG molecules. More importantly, in vivo studies reveal that the DOX-cross-linked PEG NPs exhibit favorable blood circulation half-life (>4 h) and intense accumulation in tumor areas, enabling effective anti-cancer therapy. We expect this work will provide a powerful strategy for stabilizing carrier-free nanomedicines and pave the way to their successful clinical applications in the future.

Driving Chemical Reactions in Plasmonic Nanogaps with Electrohydrodynamic Flow.

PubMed

Thrift, William J; Nguyen, Cuong Q; Darvishzadeh-Varcheie, Mahsa; Zare, Siavash; Sharac, Nicholas; Sanderson, Robert N; Dupper, Torin J; Hochbaum, Allon I; Capolino, Filippo; Abdolhosseini Qomi, Mohammad Javad; Ragan, Regina

2017-11-28

Nanoparticles from colloidal solution-with controlled composition, size, and shape-serve as excellent building blocks for plasmonic devices and metasurfaces. However, understanding hierarchical driving forces affecting the geometry of oligomers and interparticle gap spacings is still needed to fabricate high-density architectures over large areas. Here, electrohydrodynamic (EHD) flow is used as a long-range driving force to enable carbodiimide cross-linking between nanospheres and produces oligomers exhibiting sub-nanometer gap spacing over mm 2 areas. Anhydride linkers between nanospheres are observed via surface-enhanced Raman scattering (SERS) spectroscopy. The anhydride linkers are cleavable via nucleophilic substitution and enable placement of nucleophilic molecules in electromagnetic hotspots. Atomistic simulations elucidate that the transient attractive force provided by EHD flow is needed to provide a sufficient residence time for anhydride cross-linking to overcome slow reaction kinetics. This synergistic analysis shows assembly involves an interplay between long-range driving forces increasing nanoparticle-nanoparticle interactions and probability that ligands are in proximity to overcome activation energy barriers associated with short-range chemical reactions. Absorption spectroscopy and electromagnetic full-wave simulations show that variations in nanogap spacing have a greater influence on optical response than variations in close-packed oligomer geometry. The EHD flow-anhydride cross-linking assembly method enables close-packed oligomers with uniform gap spacings that produce uniform SERS enhancement factors. These results demonstrate the efficacy of colloidal driving forces to selectively enable chemical reactions leading to future assembly platforms for large-area nanodevices.

Enhanced stability of Janus nanoparticles by covalent cross-linking of surface ligands.

PubMed

Song, Yang; Klivansky, Liana M; Liu, Yi; Chen, Shaowei

2011-12-06

A mercapto derivative of diacetylene was used as the hydrophilic ligand to prepare Janus nanoparticles by using hydrophobic hexanethiolate-protected gold (AuC6, diameter 5 nm) nanoparticles as the starting materials. The amphiphilic surface characters of the Janus nanoparticles were verified by contact angle measurements, as compared to those of the bulk-exchange counterparts where the two types of ligands were distributed rather homogeneously on the nanoparticle surface. Dynamic light scattering studies showed that the Janus nanoparticles formed stable superstructures in various solvent media that were significantly larger than those by the bulk-exchange counterparts. This was ascribed to the amphiphilic characters of the Janus nanoparticles that rendered the particles to behave analogously to conventional surfactant molecules. Notably, because of the close proximity of the diacetylene moieties on the Janus nanoparticle surface, exposure to UV irradiation led to effective covalent cross-linking between the diacetylene moieties of neighboring ligands, as manifested in UV-vis and fluorescence measurements where the emission characteristics of dimers and trimers of diacetylene were rather well-defined, in addition to the monomeric emission. In contrast, for bulk-exchange nanoparticles, no trimer emission could be identified, and the intensity of dimer emission was markedly lower (though the intensity increased with increasing diacetylene coverage on the particle surface) under the otherwise identical experimental conditions. This is largely because the diacetylene ligands were distributed on the entire particle surface, and it was difficult to find a large number of ligands situated closely so that the stringent topochemical principles for the polymerization of diacetylene derivatives could be met. Importantly, the cross-linked Janus nanoparticles were found to exhibit marked enhancement of the structural integrity, which was attributable to the impeded surface diffusion of the thiol ligands on the nanoparticle surface, as manifested in fluorescence measurements of aged nanoparticles. © 2011 American Chemical Society

Guidelines for safe handling, use and disposal of nanoparticles

NASA Astrophysics Data System (ADS)

Amoabediny, G. H.; Naderi, A.; Malakootikhah, J.; Koohi, M. K.; Mortazavi, S. A.; Naderi, M.; Rashedi, H.

2009-05-01

Health, safety and environmental (HSE) risks of a technology is an inseparable part of it which threatens all exposed employees. It has been proved for many years that exposure to particles, in an occupational setting, could be linked with the onset of lung diseases, such as pneumoconiosis, chronic obstructive pulmonary disease (COPD), and mesotelioma and lung cancer. Nanoparticles, due to their unique characteristics including; small size, shape, high surface area, charge, chemical properties, solubility, and degree of agglomeration can cross cell boundaries or pass directly from the lungs into the blood stream and ultimately reach to all of the organs in the body. This is the reason why they may pose higher risk than the same mass and material of larger particles. Moreover, biodegradation of nanoparticles by some kinds of fungi (like wood decay fungi) may result in metabolites which may be toxic to microorganisms under aerobic and anaerobic conditions. Bacteria and living cells can take up nanoparticles, providing the basis for potential bioaccumulation in the food chain. Considering Iran's prominent position in nanotechnologies and fast-growing in research and industrial activities, controlling nanoparticles related HSE risks should be highly considered. In general, there are three main approaches to risk and exposure control: engineering techniques, administrative means and personal protective equipments. These complementary approaches especially engineering techniques should be considered starting with the design stage of an industrial process. Administrative means of control constitute an additional approach when the other methods have not achieved the expected control levels. Administrative means of control must never substitute for engineering techniques, which always be performed according to standard practices. In some situations, due to insufficiently advanced technology and prohibitive costs, engineering measerus can not be implemended. In these situations, performing administrative means of control constitute other ways of limiaiting the occupational exposure risks. Accordingly, to minimize the risks from know and unknown health, safety and invironment hazards in research and occupational setting of the country, guideline for safe handling, use and disposal of manopractical has provided.

Can para-aryl-dithiols cross-link two plasmonic noble nanoparticles as monolayer dithiolate spacers

USDA-ARS?s Scientific Manuscript database

Para-aryl-dithiols (PADTs, HS-(C6H4)n-SH, n = 1, 2, and 3) have been used extensively in molecular electronics, surface-enhanced Raman spectroscopy (SERS), and quantum electron tunneling between two gold or silver nanoparticles (AuNPs and AgNPs). One popular belief is that these dithiols cross-link ...

Connecting quantum dots and bionanoparticles in hybrid nanoscale ultra-thin films

NASA Astrophysics Data System (ADS)

Tangirala, Ravisubhash; Hu, Yunxia; Zhang, Qingling; He, Jinbo; Russell, Thomas; Emrick, Todd

2008-03-01

Aldehyde-functionalized CdSe quantum dots and nanorods, and horse spleen ferritin bionanoparticles, were co-assembled at an oil-water interface. Reaction of the aldehydes with the surface-available amines on the ferritin particles enabled cross-linking at the interface, converting the assembled nanoparticles into robust ultra-thin films. The cross-linked capsules and sheets thus made by aldehyde-amine conjugation could be disrupted by addition of acid. Reductive amination chemistry could be performed to convert these degradable capsules and sheets into structures with irreversible cross-linking. Fluorescence confocal microscopy, scanning force microscopy and pendant drop tensiometry were used to characterize these hybrid nanoparticle-based materials, and transmission electron microscopy (TEM) confirmed the presence of both the synthetic and naturally derived nanoparticles.

Engineered polymeric nanoparticles for soil remediation.

PubMed

Tungittiplakorn, Warapong; Lion, Leonard W; Cohen, Claude; Kim, Ju-Young

2004-03-01

Hydrophobic organic groundwater contaminants, such as polynuclear aromatic hydrocarbons (PAHs), sorb strongly to soils and are difficult to remove. We report here on the synthesis of amphiphilic polyurethane (APU) nanoparticles for use in remediation of soil contaminated with PAHs. The particles are made of polyurethane acrylate anionomer (UAA) or poly(ethylene glycol)-modified urethane acrylate (PMUA) precursor chains that can be emulsified and cross-linked in water. The resulting particles are of colloidal size (17-97 nm as measured by dynamic light scattering). APU particles have the ability to enhance PAH desorption and transport in a manner comparable to that of surfactant micelles, but unlike the surface-active components of micelles, the individual cross-linked precursor chains in APU particles are not free to sorb to the soil surface. Thus, the APU particles are stable independent of their concentration in the aqueous phase. In this paper we show that APU particles can be engineered to achieve desired properties. Our experimental results show that the APU particles can be designed to have hydrophobic interior regions that confer a high affinity for phenanthrene (PHEN) and hydrophilic surfaces that promote particle mobility in soil. The affinity of APU particles for contaminants such as PHEN can be controlled by changing the size of the hydrophobic segment used in the chain synthesis. The mobility of colloidal APU suspensions in soil is controlled by the charge density or the size of the pendent water-soluble chains that reside on the particle surface. Exemplary results are provided illustrating the influence of alternative APU particle formulations with respect to their efficacy for contaminant removal. The ability to control particle properties offers the potential to produce different nanoparticles optimized for varying contaminant types and soil conditions.

Synthesis of polyaniline (PANI) and functionalized polyaniline (F-PANI) nanoparticles with controlled size by solvent displacement method. Application in fluorescence detection and bacteria killing by photothermal effect.

PubMed

Abel, Silvestre Bongiovanni; Yslas, Edith I; Rivarola, Claudia R; Barbero, Cesar A

2018-03-23

Polyaniline nanoparticles (PANI-NPs) were easily obtained applying the solvent displacement method by using N-methylpyrrolidone (NMP) as good solvent and water as poor solvent. Different polymers such as polyvinylpyrrolidone (PVP), chondroitin sulfate (ChS), polyvinyl alcohol (PVA), and polyacrylic acid (PAA) were used as stabilizers. Dynamic light scattering and scanning electron microscopy corroborated the size and morphology of the formed NPs. It was demonstrated that the size of nanoparticles could be controlled by setting the concentration of PANI in NMP, the NMP to water ratio, and the stabilizer's nature. The functionalization and fluorescence of NPs were checked by spectroscopic techniques. Since polyaniline show only weak intrinsic luminescence, fluorescent groups were linked to the polyaniline chains prior to the nanoparticle formation using a linker. Polyaniline chains were functionalized by nucleophilic addition of cysteamine trough the thiol group thereby incorporating pendant primary aliphatic amine groups to the polyaniline backbone. Then, dansyl chloride (DNS-Cl), which could act as an extrinsic chromophore, was conjugated to the amine pendant groups. Later, the functionalized polyaniline was used to produce nanoparticles by solvent displacement. The optical and functional properties of fluorescent nanoparticles (F-PANI-NPs) were determined. F-PANI-NPs in the conductive state (pH < 4) are able to absorb near infrared radiation (NIR) creating a photothermal effect in an aqueous medium. Thus, multifunctional nanoparticles are obtained. The application of NIR on a F-PANI-NPs dispersion in contact with Pseudomonas aeruginosa causes bacterial death. Therefore, the F-PANI-NPs could be tracked and applied to inhibit different diseases caused by pathogenic microorganisms and resistant to antibiotics as well as a new disinfection method to surgical materials.

Silicone nanoparticles do not induce immune responses by naïve human peripheral blood mononuclear cells: implications in breast implants.

PubMed

Nair, Narayanan; Pilakka-Kanthikeel, Sudheesh; Saiyed, Zainulabedin; Yndart, Adriana; Nair, Madhavan

2012-07-01

Several studies have reported adverse immunological effects of silicone due to their ability to induce proinflammatory molecules, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). In recent years, use of nanoparticles has been under fast development for therapeutic drug targeting, diagnostic imaging, and immune response in various fields of nanomedicine. The authors hypothesize that immune responses induced by in vivo use of silicone materials can be reduced or eliminated by the use of nanosilicone. Peripheral blood mononuclear cells obtained from naïve normal subjects were cultured with different concentrations of silicone nanoparticles and microparticles for 24 hours. The culture supernatants were quantitated for TNF-α, IL-6, and interferon-γ (IFN-γ) secretion by enzyme-linked immunosorbent assay. The pellets were used for specific IL-6, TNF-α, and IFN-γ gene expression by real-time polymerase chain reaction, respectively. Cytotoxicity was evaluated by XTT viability assay. Results were compared between silicone nanoparticles and microparticles and untreated controls. Silicone nanoparticles up to 100 μg/ml did not induce any detectable levels of specific TNF-α, IFN-γ, and IL-6 gene expression and protein production and the results were comparable to those for untreated controls. Silicone microparticles at 100 μg/ml, however, significantly induced the production and gene expression of TNF-α, IL-6, and IFN-γ by peripheral blood mononuclear cells. XTT viability assay showed that silicone nanoparticles or microparticles, even at the highest concentration used, were not cytotoxic to cells. The results suggest that silicone nanoparticles can be engineered to avoid immune recognition and subsequent silicone microparticle-related adverse effects and thus may be of therapeutic significance in the cosmetic industry, plastic surgery, and aesthetic medicine.

Synthesis of polyaniline (PANI) and functionalized polyaniline (F-PANI) nanoparticles with controlled size by solvent displacement method. Application in fluorescence detection and bacteria killing by photothermal effect

NASA Astrophysics Data System (ADS)

Bongiovanni Abel, Silvestre; Yslas, Edith I.; Rivarola, Claudia R.; Barbero, Cesar A.

2018-03-01

Polyaniline nanoparticles (PANI-NPs) were easily obtained applying the solvent displacement method by using N-methylpyrrolidone (NMP) as good solvent and water as poor solvent. Different polymers such as polyvinylpyrrolidone (PVP), chondroitin sulfate (ChS), polyvinyl alcohol (PVA), and polyacrylic acid (PAA) were used as stabilizers. Dynamic light scattering and scanning electron microscopy corroborated the size and morphology of the formed NPs. It was demonstrated that the size of nanoparticles could be controlled by setting the concentration of PANI in NMP, the NMP to water ratio, and the stabilizer’s nature. The functionalization and fluorescence of NPs were checked by spectroscopic techniques. Since polyaniline show only weak intrinsic luminescence, fluorescent groups were linked to the polyaniline chains prior to the nanoparticle formation using a linker. Polyaniline chains were functionalized by nucleophilic addition of cysteamine trough the thiol group thereby incorporating pendant primary aliphatic amine groups to the polyaniline backbone. Then, dansyl chloride (DNS-Cl), which could act as an extrinsic chromophore, was conjugated to the amine pendant groups. Later, the functionalized polyaniline was used to produce nanoparticles by solvent displacement. The optical and functional properties of fluorescent nanoparticles (F-PANI-NPs) were determined. F-PANI-NPs in the conductive state (pH < 4) are able to absorb near infrared radiation (NIR) creating a photothermal effect in an aqueous medium. Thus, multifunctional nanoparticles are obtained. The application of NIR on a F-PANI-NPs dispersion in contact with Pseudomonas aeruginosa causes bacterial death. Therefore, the F-PANI-NPs could be tracked and applied to inhibit different diseases caused by pathogenic microorganisms and resistant to antibiotics as well as a new disinfection method to surgical materials.

Control of single-electron charging of metallic nanoparticles onto amorphous silicon surface.

PubMed

Weis, Martin; Gmucová, Katarína; Nádazdy, Vojtech; Capek, Ignác; Satka, Alexander; Kopáni, Martin; Cirák, Július; Majková, Eva

2008-11-01

Sequential single-electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir-Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film is reported. Single-electron charging (so-called quantized double-layer charging) of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the electric field in the surface region induced by the excess of negative/positive charged defect states in the amorphous silicon layer. The particular charge states in amorphous silicon are created by the simultaneous application of a suitable bias voltage and illumination before the measurement. The influence of charged states on the electric field in the surface region is evaluated by the finite element method. The single-electron charging is analyzed by the standard quantized double layer model as well as two weak-link junctions model. Both approaches are in accordance with experiment and confirm single-electron charging by tunnelling process at room temperature. This experiment illustrates the possibility of the creation of a voltage-controlled capacitor for nanotechnology.

Biotin Decorated Gold Nanoparticles for Targeted Delivery of a Smart-Linked Anticancer Active Copper Complex: In Vitro and In Vivo Studies.

PubMed

Pramanik, Anup K; Siddikuzzaman; Palanimuthu, Duraippandi; Somasundaram, Kumaravel; Samuelson, Ashoka G

2016-12-21

The synthesis and anticancer activity of a copper(II) diacetyl-bis(N4-methylthiosemicarbazone) complex and its nanoconjugates are reported. The copper(II) complex is connected to a carboxylic acid group through a cleavable disulfide link to enable smart delivery. The copper complex is tethered to highly water-soluble 20 nm gold nanoparticles (AuNPs), stabilized by amine terminated lipoic acid-polyethylene glycol (PEG). The gold nanoparticle carrier was further decorated with biotin to achieve targeted action. The copper complex and the conjugates with and without biotin, were tested against HeLa and HaCaT cells. They show very good anticancer activity against HeLa cells, a cell line derived from cervical cancer and are less active against HaCaT cells. Slow and sustained release of the complex from conjugates is demonstrated through cleavage of disulfide linker in the presence of glutathione (GSH), a reducing agent intrinsically present in high concentrations within cancer cells. Biotin appended conjugates do not show greater activity than conjugates without biotin against HeLa cells. This is consistent with drug uptake studies, which suggests similar uptake profiles for both conjugates in vitro. However, in vivo studies using a HeLa cell xenograft tumor model shows 3.8-fold reduction in tumor volume for the biotin conjugated nanoparticle compared to the control whereas the conjugate without biotin shows only 2.3-fold reduction in the tumor volume suggesting significant targeting.

Controllable fabrication of Pt nanocatalyst supported on N-doped carbon containing nickel nanoparticles for ethanol oxidation.

PubMed

Yu, Jianguo; Dai, Tangming; Cao, Yuechao; Qu, Yuning; Li, Yao; Li, Juan; Zhao, Yongnan; Gao, Haiyan

2018-08-15

In this paper, platinum nanoparticles were deposited on a carbon carrier with the partly graphitized carbon and the highly dispersive carbon-coated nickel particles. An efficient electron transfer structure can be fabricated by controlling the contents of the deposited platinum. The high resolution transmission electron microscopy images of Pt 2 /Ni@C N-doped sample prove the electron transfer channel from Pt (1 1 1) crystal planes to graphite (1 0 0) or Ni (1 1 1) crystal planes due to these linked together crystal planes. The Pt 3 /Ni@C N-doped with low Pt contents cannot form the electron transfer structure and the Pt 1 /Ni@C N-doped with high Pt contents show an obvious aggregation of Pt nanoparticles. The electrochemical tests of all the catalysts show that the Pt 2 /Ni@C N-doped sample presents the highest catalytic activity, the strongest CO tolerance and the best catalytic stability. The high performance is attributed to the efficient electronic transport structure of the Pt 2 /Ni@C N-doped sample and the synergistic effect between Pt and Ni nanoparticles. This paper provides a promising method for enhancing the conductivity of electrode material. Copyright © 2018 Elsevier Inc. All rights reserved.

Directional emission from dye-functionalized plasmonic DNA superlattice microcavities

PubMed Central

Park, Daniel J.; Ku, Jessie C.; Sun, Lin; Lethiec, Clotilde M.; Stern, Nathaniel P.; Schatz, George C.; Mirkin, Chad A.

2017-01-01

Three-dimensional plasmonic superlattice microcavities, made from programmable atom equivalents comprising gold nanoparticles functionalized with DNA, are used as a testbed to study directional light emission. DNA-guided nanoparticle colloidal crystallization allows for the formation of micrometer-scale single-crystal body-centered cubic gold nanoparticle superlattices, with dye molecules coupled to the DNA strands that link the particles together, in the form of a rhombic dodecahedron. Encapsulation in silica allows one to create robust architectures with the plasmonically active particles and dye molecules fixed in space. At the micrometer scale, the anisotropic rhombic dodecahedron crystal habit couples with photonic modes to give directional light emission. At the nanoscale, the interaction between the dye dipoles and surface plasmons can be finely tuned by coupling the dye molecules to specific sites of the DNA particle-linker strands, thereby modulating dye–nanoparticle distance (three different positions are studied). The ability to control dye position with subnanometer precision allows one to systematically tune plasmon–excition interaction strength and decay lifetime, the results of which have been supported by electrodynamics calculations that span length scales from nanometers to micrometers. The unique ability to control surface plasmon/exciton interactions within such superlattice microcavities will catalyze studies involving quantum optics, plasmon laser physics, strong coupling, and nonlinear phenomena. PMID:28053232

Biosynthesis of insulin-silk fibroin nanoparticles conjugates and in vitro evaluation of a drug delivery system

NASA Astrophysics Data System (ADS)

Yan, Hai-Bo; Zhang, Yu-Qing; Ma, Yong-Lei; Zhou, Li-Xia

2009-11-01

Silk fibroin derived from Bombyx mori is a biomacromolecular protein with outstanding biocompatibility. When it was dissolved in highly concentrated CaCl2 solution and then the mixture of the protein and salt was subjected to desalting treatments for long time in flowing water, the resulting liquid silk was water-soluble polypeptides with different molecular masses, ranging from 8 to 70 kDa. When the liquid silk was introduced rapidly into acetone, silk protein nanoparticles with a range of 40-120 nm in diameter could be obtained. The crystalline silk nanoparticles could be conjugated covalently with insulin alone with cross-linking reagent glutaraldehyde. In vitro properties of the insulin-silk fibroin nanoparticles (Ins-SFN) bioconjugates were determined by Enzyme-Linked Immunosorbent Assay (ELISA). The optimal conditions for the biosynthesis of Ins-SFN bioconjugates were investigated. The Ins-SFN constructs obtained by 8 h of covalent cross-linking with 0.7% cross-linking reagent and the proportion of insulin and SFN being 30 IU: 15 mg showed much higher recoveries (90-115%). When insulin was coupled covalently with silk nanoparticles, the resistance of the modified insulin to trypsin digestion and in vitro stability in human serum were greatly enhanced as compared with insulin alone. The results in human serum indicated that the half-life in vitro of the biosynthesized Ins-SFN derivatives was about 2.5 times more than that of native insulin. Therefore, the silk protein nanoparticles have the potential values for being studied and developed as a new bioconjugate for enzyme/polypeptide drug delivery system.

Using Amphiphilic Copolymers and Nanoparticles to Organize Charged Biopolymers

NASA Astrophysics Data System (ADS)

Park, Jung Hyun; McConnell, Marla; Sun, Yujie; Goldman, Yale; Composto, Russell

2009-03-01

Nanoparticles (NPs) on amphiphilic random copolymers control filamentous actin (F-actin) attachment. 3-aminopropyltriethoxysilane (APTES) coated silica NPs are selectively bonded to acrylic acid groups on the surface of a poly(styrene-r-acrylic acid) (PS-r-PAA) film. By changing the concentration of NPs in the medium, the surface density of positively charged anchors is tuned. Using total internal reflection fluorescence (TIRF) microscopy, immobilization of F-actin is observed via electrostatic interaction with NPs at high NP coverages. Below a critical coverage, F-actin is weakly attached and undergoes thermal fluctuations near the surface. Another method to tune F-actin attachment is to use APTES to cross-link and create positive charge in PAA films. Here, the surface coverage of F-actin decreases as APTES concentration increases. This observation is attributed to an increase in surface roughness and hydrophobicity that reduces the effective surface sites that attract F-actin. In addition, in-situ G-actin polymerization to F-actin is observed on both the NP and cross-linked PAA templates.

Covalent modification of pericardial patches for sustained rapamycin delivery inhibits venous neointimal hyperplasia

PubMed Central

Bai, Hualong; Lee, Jung Seok; Chen, Elizabeth; Wang, Mo; Xing, Ying; Fahmy, Tarek M.; Dardik, Alan

2017-01-01

Prosthetic grafts and patches are commonly used in cardiovascular surgery, however neointimal hyperplasia remains a significant concern, especially under low flow conditions. We hypothesized that delivery of rapamycin from nanoparticles (NP) covalently attached to patches allows sustained site-specific delivery of therapeutic agents targeted to inhibit localized neointimal hyperplasia. NP were covalently linked to pericardial patches using EDC/NHS chemistry and could deliver at least 360 ng rapamycin per patch without detectable rapamycin in serum; nanoparticles were detectable in the liver, kidney and spleen but no other sites within 24 hours. In a rat venous patch angioplasty model, control patches developed robust neointimal hyperplasia on the patch luminal surface characterized by Eph-B4-positive endothelium and underlying SMC and infiltrating cells such as macrophages and leukocytes. Patches delivering rapamycin developed less neointimal hyperplasia, less smooth muscle cell proliferation, and had fewer infiltrating cells but retained endothelialization. NP covalently linked to pericardial patches are a novel composite delivery system that allows sustained site-specific delivery of therapeutics; NP delivering rapamycin inhibit patch neointimal hyperplasia. NP linked to patches may represent a next generation of tissue engineered cardiovascular implants. PMID:28071663

Covalent modification of pericardial patches for sustained rapamycin delivery inhibits venous neointimal hyperplasia

NASA Astrophysics Data System (ADS)

Bai, Hualong; Lee, Jung Seok; Chen, Elizabeth; Wang, Mo; Xing, Ying; Fahmy, Tarek M.; Dardik, Alan

2017-01-01

Prosthetic grafts and patches are commonly used in cardiovascular surgery, however neointimal hyperplasia remains a significant concern, especially under low flow conditions. We hypothesized that delivery of rapamycin from nanoparticles (NP) covalently attached to patches allows sustained site-specific delivery of therapeutic agents targeted to inhibit localized neointimal hyperplasia. NP were covalently linked to pericardial patches using EDC/NHS chemistry and could deliver at least 360 ng rapamycin per patch without detectable rapamycin in serum; nanoparticles were detectable in the liver, kidney and spleen but no other sites within 24 hours. In a rat venous patch angioplasty model, control patches developed robust neointimal hyperplasia on the patch luminal surface characterized by Eph-B4-positive endothelium and underlying SMC and infiltrating cells such as macrophages and leukocytes. Patches delivering rapamycin developed less neointimal hyperplasia, less smooth muscle cell proliferation, and had fewer infiltrating cells but retained endothelialization. NP covalently linked to pericardial patches are a novel composite delivery system that allows sustained site-specific delivery of therapeutics; NP delivering rapamycin inhibit patch neointimal hyperplasia. NP linked to patches may represent a next generation of tissue engineered cardiovascular implants.

Enhanced Stability and Bioconjugation of Photo-cross-linked Polystyrene-Shell, Au-Core Nanoparticles

PubMed Central

Chen, Ying; Cho, Juhee; Young, Alexi; Taton, T. Andrew

2008-01-01

Encapsulating Au nanoparticles within a shell of photo-cross-linked block copolymer surfactant dramatically improves the physical and chemical stability of the nanoparticles, particularly when they are applied as bioconjugates. Photo-cross-linkable block copolymer amphiphiles [polystyrene-co-poly(4-vinyl benzophenone)]-block-poly(acrylic acid) [(PS-co-PVBP)-b-PAA] and [poly(styrene)-co-poly(4-vinyl benzophenone)]-block-poly(ethylene oxide) [(PS-co-PVBP)-b-PEO] were assembled around Au nanoparticles ranging from 12 nm to 108 nm in diameter. UV irradiation cross-linked the PVBP groups on the polymer to yield particles that withstood extremes of temperature, ionic strength, and chemical etching. Streptavidin was attached to [PS-co-PVBP]-b-PAA coated particles using the same noncovalent and covalent conjugation protocols used to bind biomolecules to divinylbenzene-crosslinked polystyrene microspheres. We expect that these particles will be useful as plasmonic, highly light-scattering and light-absorbing analogs to fluorescently labeled polystyrene nanospheres. PMID:17530871

Plasmon-Based Colorimetric Nanosensors for Ultrasensitive Molecular Diagnostics.

PubMed

Tang, Longhua; Li, Jinghong

2017-07-28

Colorimetric detection of target analytes with high specificity and sensitivity is of fundamental importance to clinical and personalized point-of-care diagnostics. Because of their extraordinary optical properties, plasmonic nanomaterials have been introduced into colorimetric sensing systems, which provide significantly improved sensitivity in various biosensing applications. Here we review the recent progress on these plasmonic nanoparticles-based colorimetric nanosensors for ultrasensitive molecular diagnostics. According to their different colorimetric signal generation mechanisms, these plasmonic nanosensors are classified into two categories: (1) interparticle distance-dependent colorimetric assay based on target-induced forming cross-linking assembly/aggregate of plasmonic nanoparticles; and (2) size/morphology-dependent colorimetric assay by target-controlled growth/etching of the plasmonic nanoparticles. The sensing fundamentals and cutting-edge applications will be provided for each of them, particularly focusing on signal generation and/or amplification mechanisms that realize ultrasensitive molecular detection. Finally, we also discuss the challenge and give our future perspective in this emerging field.

Anti-cancer, pharmacokinetics and tumor localization studies of pH-, RF- and thermo-responsive nanoparticles.

PubMed

Sanoj Rejinold, N; Thomas, Reju George; Muthiah, Muthunarayanan; Chennazhi, K P; Manzoor, K; Park, In-Kyu; Jeong, Yong Yeon; Jayakumar, R

2015-03-01

The curcumin-encapsulated chitosan-graft-poly(N-vinyl caprolactam) nanoparticles containing gold nanoparticles (Au-CRC-TRC-NPs) were developed by ionic cross-linking method. After "optimum RF exposure" at 40 W for 5 min, Au-CRC-TRC-NPs dissipated heat energy in the range of ∼42°C, the lower critical solution temperature (LCST) of chitosan-graft-poly(N-vinyl caprolactam), causing controlled curcumin release and apoptosis to cancer cells. Further, in vivo PK/PD studies on swiss albino mice revealed that Au-CRC-TRC-NPs could be sustained in circulation for a week with no harm to internal organs. The colon tumor localization studies revealed that Au-CRC-TRC-NPs were retained in tumor for a week. These results throw light on their feasibility as multi-responsive nanomedicine for RF-assisted cancer treatment modalities. Copyright © 2014 Elsevier B.V. All rights reserved.

Cleavable ester linked magnetic nanoparticles for labeling of solvent exposed primary amine groups of peptides/proteins

USDA-ARS?s Scientific Manuscript database

In order to study the solvent exposed lysine residues of peptides/proteins, we previously reported disulfide linked N-hydrosuccinimide ester modified silica coated iron oxide magnetic nanoparticles (NHS-SS-SiO2@Fe3O4 MNPs). The presence of a disulfide bond in the linker limits the use of disulfide r...

Albumin nanoparticles coated with polysorbate 80 as a novel drug carrier for the delivery of antiretroviral drug—Efavirenz

PubMed Central

Jenita, Josephine Leno; Chocalingam, Vijaya; Wilson, Barnabas

2014-01-01

Purpose of the study: The antiretroviral therapy (ART) has dramatically improved human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) treatment, prevention and also has been found to increase the lifespan of HIV/AIDS patients by providing durable control of the HIV replication in patients. Efavirenz is a non-nucleoside reverse transcriptase inhibitor of HIV-1. The purpose of this study is to formulate efavirenz-loaded bovine serum albumin nanoparticles to improve efavirenz delivery into various organs. Materials and Methods: Nanoparticles were prepared by desolvation technique and coated with polysorbate 80. Ethanol, glutaraldehyde, and mannitol were used as desolvating, cross linking agent, and cryoprotectant, respectively. Drug to polymer ratio was chosen at five levels from 1:2, 1:3, 1:4, 1:5, and 1:6 (by weight). The formulated nanoparticles were characterized for Fourier Transform Infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) studies, entrapment efficiency, particle size, surface charge, surface morphology, in vitro drug release, release kinetics, stability studies, and biodistribution studies. Results and Major Conclusion: The particle size of the prepared formulations was found below 250nm with narrow size distribution, spherical in shape and showed good entrapment efficiency (45.62-72.49%). The in vitro drug release indicated biphasic release and its data were fitted to release kinetics models and release pattern was Fickian diffusion controlled release profile. The prepared nanoparticles increased efavirenz delivery into various organs by several fold in comparison with the free drug. PMID:25126528

Poly(iohexol) nanoparticles as contrast agents for in vivo X-ray computed tomography imaging.

PubMed

Yin, Qian; Yap, Felix Y; Yin, Lichen; Ma, Liang; Zhou, Qin; Dobrucki, Lawrence W; Fan, Timothy M; Gaba, Ron C; Cheng, Jianjun

2013-09-18

Biocompatible poly(iohexol) nanoparticles, prepared through cross-linking of iohexol and hexamethylene diisocyanate followed by coprecipitation of the resulting cross-linked polymer with mPEG-polylactide, were utilized as contrast agents for in vivo X-ray computed tomography (CT) imaging. Compared to conventional small-molecule contrast agents, poly(iohexol) nanoparticles exhibited substantially protracted retention within the tumor bed and a 36-fold increase in CT contrast 4 h post injection, which makes it possible to acquire CT images with improved diagnosis accuracy over a broad time frame without multiple administrations.

In vivo nanoparticle imaging of innate immune cells can serve as a marker of disease severity in a model of multiple sclerosis.

PubMed

Kirschbaum, Klara; Sonner, Jana K; Zeller, Matthias W; Deumelandt, Katrin; Bode, Julia; Sharma, Rakesh; Krüwel, Thomas; Fischer, Manuel; Hoffmann, Angelika; Costa da Silva, Milene; Muckenthaler, Martina U; Wick, Wolfgang; Tews, Björn; Chen, John W; Heiland, Sabine; Bendszus, Martin; Platten, Michael; Breckwoldt, Michael O

2016-11-15

Innate immune cells play a key role in the pathogenesis of multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Current clinical imaging is restricted to visualizing secondary effects of inflammation, such as gliosis and blood-brain barrier disruption. Advanced molecular imaging, such as iron oxide nanoparticle imaging, can allow direct imaging of cellular and molecular activity, but the exact cell types that phagocytose nanoparticles in vivo and how phagocytic activity relates to disease severity is not well understood. In this study we used MRI to map inflammatory infiltrates using high-field MRI and fluorescently labeled cross-linked iron oxide nanoparticles for cell tracking. We confirmed nanoparticle uptake and MR detectability ex vivo. Using in vivo MRI, we identified extensive nanoparticle signal in the cerebellar white matter and circumscribed cortical gray matter lesions that developed during the disease course (4.6-fold increase of nanoparticle accumulation in EAE compared with healthy controls, P < 0.001). Nanoparticles showed good cellular specificity for innate immune cells in vivo, labeling activated microglia, infiltrating macrophages, and neutrophils, whereas there was only sparse uptake by adaptive immune cells. Importantly, nanoparticle signal correlated better with clinical disease than conventional gadolinium (Gd) imaging (r, 0.83 for nanoparticles vs. 0.71 for Gd-imaging, P < 0.001). We validated our approach using the Food and Drug Administration-approved iron oxide nanoparticle ferumoxytol. Our results show that noninvasive molecular imaging of innate immune responses can serve as an imaging biomarker of disease activity in autoimmune-mediated neuroinflammation with potential clinical applications in a wide range of inflammatory diseases.

A facile strategy for fine-tuning the stability and drug release of stimuli-responsive cross-linked micellar nanoparticles towards precision drug delivery.

PubMed

Xiao, Kai; Lin, Tzu-Yin; Lam, Kit S; Li, Yuanpei

2017-06-14

Precision drug delivery has a great impact on the application of precision oncology for better patient care. Here we report a facile strategy for fine-tuning the stability, drug release and responsiveness of stimuli-responsive cross-linked nanoparticles towards precision drug delivery. A series of micellar nanoparticles with different levels of intramicellar disulfide crosslinkages could be conveniently produced with a mixed micelle approach. These micellar nanoparticles were all within a size range of 25-40 nm so that they could take full advantage of the enhanced permeability and retention (EPR) effect for tumor-targeted drug delivery. The properties of these nanoparticles such as critical micelle concentration (CMC), stability, drug release and responsiveness to a reductive environment could be well correlated with the levels of crosslinking (LOC). Compared to the micellar nanoparticles with a LOC at 0% that caused the death of animals of two species (mouse and rat) due to the acute toxicity such as hemolysis, the nanoparticles at all other levels of crosslinking were much safer to be administered into animals. The in vitro antitumor efficacy of micellar nanoparticles crosslinked at lower levels (20% & 50%) were much more effective than that of 100% crosslinked micellar nanoparticles in SKOV-3 ovarian cancer cells.

Fabrication and evaluation of magnetic phosphodiesterase-5 linked nanoparticles as adsorbent for magnetic dispersive solid-phase extraction of inhibitors from Chinese herbal medicine prior to ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis.

PubMed

Tao, Yi; Gu, Xianghui; Li, Weidong; Cai, Baochang

2018-01-12

In the present study, the preparation of the magnetic phosphodiesterase-5 linked Fe 3 O 4 @ SiO 2 nanoparticles was successfully achieved by amide reaction and the magnetic phosphodiesterase-5 linked Fe 3 O 4 @SiO 2 nanoparticles were evaluated as a new adsorbent for magnetic dispersive solid-phase extraction of ligands from medicinal plant samples before the analysis by UHPLC-Q-TOF/MS. The prepared phosphodiesterase-5 linked Fe 3 O 4 @SiO 2 nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, vibration sample magnetometer and potential laser particle size analyzer. The effects of EDC concentration, incubation time and bead-protein ratio on the amount of immobilized protein were studied. The main experimental parameters affect extraction efficiency of ligands, such as wash times, wash solvents, incubation pH, ion strength and incubation temperature, were investigated and optimized by using echinacoside as a model compound. The absolute recovery of echinacoside was ranged from 98.36%-102.16% in Cistanche tubulosa sample under the optimal extraction conditions. Good linearity was observed in the investigated concentration range of 0.006 mgmL -1 -0.97 mgmL -1 (R 2  = 0.9999). The limit of detection was 0.002 mgmL -1 . The RSDs of within-day and between-day precision were less than 2.3%. Due to the excellent magnetic behavior of Fe 3 O 4 @SiO 2 nanoparticles, the proposed method was shown to be simple and rapid. Remarkably, the magnetic phosphodiesterase-5 linked Fe 3 O 4 @SiO 2 nanoparticles could be recycled for ten times with loss of 10% activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Paclitaxel Albumin-stabilized Nanoparticle Formulation

Cancer.gov

This page contains brief information about paclitaxel albumin-stabilized nanoparticle formulation and a collection of links to more information about the use of this drug, research results, and ongoing clinical trials.

Fabrication of nanoscale heterostructures comprised of graphene-encapsulated gold nanoparticles and semiconducting quantum dots for photocatalysis.

PubMed

Li, Yuan; Chopra, Nitin

2015-05-21

Patterned growth of multilayer graphene shell encapsulated gold nanoparticles (GNPs) and their covalent linking with inorganic quantum dots are demonstrated. GNPs were grown using a xylene chemical vapor deposition process, where the surface oxidized gold nanoparticles catalyze the multilayer graphene shell growth in a single step process. The graphene shell encapsulating gold nanoparticles could be further functionalized with carboxylic groups, which were covalently linked to amine-terminated quantum dots resulting in GNP-quantum dot heterostructures. The compositions, morphologies, crystallinity, and surface functionalization of GNPs and their heterostructures with quantum dots were evaluated using microscopic, spectroscopic, and analytical methods. Furthermore, optical properties of the derived architectures were studied using both experimental methods and simulations. Finally, GNP-quantum dot heterostructures were studied for photocatalytic degradation of phenol.

Smart surface coating of drug nanoparticles with cross-linkable polyethylene glycol for bio-responsive and highly efficient drug delivery

NASA Astrophysics Data System (ADS)

Wei, Weijia; Zhang, Xiujuan; Chen, Xianfeng; Zhou, Mengjiao; Xu, Ruirui; Zhang, Xiaohong

2016-04-01

Many drug molecules can be directly used as nanomedicine without the requirement of any inorganic or organic carriers such as silica and liposome nanostructures. This new type of carrier-free drug nanoparticles (NPs) has great potential in clinical treatment because of its ultra-high drug loading capacity and biodegradability. For practical applications, it is essential for such nanomedicine to possess robust stability and minimal premature release of therapeutic molecules during circulation in the blood stream. To meet this requirement, herein, we develop GSH-responsive and crosslinkable amphiphilic polyethylene glycol (PEG) molecules to modify carrier-free drug NPs. These PEG molecules can be cross-linked on the surface of the NPs to endow them with greater stability and the cross-link is sensitive to intracellular environment for bio-responsive drug release. With this elegant design, our experimental results show that the liberation of DOX from DOX-cross-linked PEG NPs is dramatically slower than that from DOX-non-cross-linked PEG NPs, and the DOX release profile can be controlled by tuning the concentration of the reducing agent to break the cross-link between PEG molecules. More importantly, in vivo studies reveal that the DOX-cross-linked PEG NPs exhibit favorable blood circulation half-life (>4 h) and intense accumulation in tumor areas, enabling effective anti-cancer therapy. We expect this work will provide a powerful strategy for stabilizing carrier-free nanomedicines and pave the way to their successful clinical applications in the future.Many drug molecules can be directly used as nanomedicine without the requirement of any inorganic or organic carriers such as silica and liposome nanostructures. This new type of carrier-free drug nanoparticles (NPs) has great potential in clinical treatment because of its ultra-high drug loading capacity and biodegradability. For practical applications, it is essential for such nanomedicine to possess robust stability and minimal premature release of therapeutic molecules during circulation in the blood stream. To meet this requirement, herein, we develop GSH-responsive and crosslinkable amphiphilic polyethylene glycol (PEG) molecules to modify carrier-free drug NPs. These PEG molecules can be cross-linked on the surface of the NPs to endow them with greater stability and the cross-link is sensitive to intracellular environment for bio-responsive drug release. With this elegant design, our experimental results show that the liberation of DOX from DOX-cross-linked PEG NPs is dramatically slower than that from DOX-non-cross-linked PEG NPs, and the DOX release profile can be controlled by tuning the concentration of the reducing agent to break the cross-link between PEG molecules. More importantly, in vivo studies reveal that the DOX-cross-linked PEG NPs exhibit favorable blood circulation half-life (>4 h) and intense accumulation in tumor areas, enabling effective anti-cancer therapy. We expect this work will provide a powerful strategy for stabilizing carrier-free nanomedicines and pave the way to their successful clinical applications in the future. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09167e

Let there be light: photo-cross-linked block copolymer nanoparticles.

PubMed

Roy, Debashish; Sumerlin, Brent S

2014-01-01

Polymeric nanoparticles are prepared by selectively cross-linking a photo-sensitive dimethylmaleimide-containing block of a diblock copolymer via UV irradiation. A well-defined photo-cross-linkable block copolymer is prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization of a dimethylmaleimide-functional acrylamido monomer containing photoreactive pendant groups with a poly(N,N-dimethylacrylamide) (PDMA) macro-chain transfer agent. The resulting amphiphilic block copolymers form micelles in water with a hydrophilic PDMA shell and a hydrophobic photo-cross-linkable dimethylmaleimide-containing core. UV irradiation results in photodimerization of the dimethylmaleimide groups within the micelle cores to yield core-cross-linked aggregates. Alternatively, UV irradiation of homogeneous solutions of the block copolymer in a non-selective solvent leads to in situ nanoparticle formation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermally Stable Gold Nanoparticles with a Crosslinked Diblock Copolymer Shell

NASA Astrophysics Data System (ADS)

Jang, Se Gyu; Khan, Anzar; Hawker, Craig J.; Kramer, Edward J.

2010-03-01

The use of polymer-coated Au nanoparticles prepared using oligomeric- or polymeric-ligands tethered by Au-S bonds for incorporation into block copolymer templates under thermal processing has been limited due to dissociation of the Au-S bond at T > 100^oC where compromises their colloidal stability. We report a simple route to prepare sub-5nm gold nanoparticles with a thermally stable polymeric shell. An end-functional thiol ligand consisting of poly(styrene-b-1,2&3,4-isoprene-SH) is synthesized by anionic polymerization. After a standard thiol ligand synthesis of Au nanoparticles, the inner PI block is cross-linked through reaction with 1,1,3,3-tetramethyldisiloxane. Gold nanoparticles with the cross-linked shell are stable in organic solvents at 160^oC as well as in block copolymer films of PS-b-P2VP annealed in vacuum at 170^oC for several days. These nanoparticles can be designed to strongly segregate to the PS-P2VP interface resulting in very large Au nanoparticle volume fractions φp without macrophase separation as well as transitions between lamellar and bicontinuous morphologies as φp increases.

Electrochemical and anticorrosion behaviors of hybrid functionalized graphite nano-platelets/tripolyphosphate in epoxy-coated carbon steel

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

Mohammadi, Somayeh, E-mail: somaye.mohammadi32@aut.ac.ir; Shariatpanahi, Homeira; Taromi, Faramarz Afshar

Highlights: • FGNP was combined with TPP to obtain a hybrid nano-particle. • TEM image showed uniform distribution of the hybrid nanoparticles in epoxy coating. • FGNP is a substrate for linking of TPP anions by hydrogen bonding. • FGNP as an accelerator, provides rapid iron phosphate passive film formation. • The hybrid nano-particle can provide long-term corrosion protection. - Abstract: Functionalized graphite nano-platelets (FGNP) were combined with tripolyphosphate (TPP) to gain a hybrid nano-particle (FGNP-TPP) with homogenous dispersion in epoxy, resulting in an excellent anti-corrosion coating for carbon steel substrate. Characterization analyses of the hybrid nano-particle were performed bymore » FT-IR, SEM, XRD and TEM. TPP was linked to FGNP nano-particles by hydrogen bondings. Different epoxy coatings formulated with 1 wt.% of FGNP, FGNP-TPP and TPP were evaluated. Electrochemical investigations, salt spray and pull-off tests showed that the hybrid nano-particle can provide long-term corrosion protection compared to FGNP and TPP due to synergistic effect between FGNP as an accelerator and TPP as a corrosion inhibitor to produce a uniform and stable iron-phosphate passive film with high surface coverage.« less

Multifunctional Nanoparticles as Biocompatible Targeted Probes for Human Cancer Diagnosis and Therapy

PubMed Central

Yong, Ken-Tye; Roy, Indrajit; Swihart, Mark T.; Prasad, Paras N.

2009-01-01

The use of nanoparticles in biological application has been rapidly advancing toward practical applications in human cancer diagnosis and therapy. Upon linking the nanoparticles with biomolecules, they can be used to locate cancerous area as well as for traceable drug delivery with high affinity and specificity. In this review, we discuss the engineering of multifunctional nanoparticle probes and their use in bioimaging and nanomedicine. PMID:20305738

Vapor Sensing Using Conjugated Molecule-Linked Au Nanoparticles in a Silica Matrix

DOE PAGES

Dirk, Shawn M.; Howell, Stephen W.; Price, B. Katherine; ...

2009-01-01

Cross-linkedmore » assemblies of nanoparticles are of great value as chemiresistor-type sensors. Herein, we report a simple method to fabricate a chemiresistor-type sensor that minimizes the swelling transduction mechanism while optimizing the change in dielectric response. Sensors prepared with this methodology showed enhanced chemoselectivity for phosphonates which are useful surrogates for chemical weapons. Chemoselective sensors were fabricated using an aqueous solution of gold nanoparticles that were then cross-linked in the presence of the silica precursor, tetraethyl orthosilicate with the α -, ω -dithiolate (which is derived from the in situ deprotection of 1,4-di(Phenylethynyl- 4 ′ , 4 ″ -diacetylthio)-benzene ( 1 ) with wet triethylamine). The cross-linked nanoparticles and silica matrix were drop coated onto interdigitated electrodes having 8  μ m spacing. Samples were exposed to a series of analytes including dimethyl methylphosphonate (DMMP), octane, and toluene. A limit of detection was obtained for each analyte. Sensors assembled in this fashion were more sensitive to dimethyl methylphosphonate than to octane by a factor of 1000.« less

Gram scale synthesis of Fe/Fe xO y core–shell nanoparticles and their incorporation into matrix-free superparamagnetic nanocomposites

DOE PAGES

Watt, John Daniel; Bleier, Grant C.; Romero, Zachary William; ...

2018-05-15

In this paper, significant reductions recently seen in the size of wide-bandgap power electronics have not been accompanied by a relative decrease in the size of the corresponding magnetic components. To achieve this, a new generation of materials with high magnetic saturation and permeability are needed. Here, we develop gram-scale syntheses of superparamagnetic Fe/Fe xO y core–shell nanoparticles and incorporate them as the magnetic component in a strongly magnetic nanocomposite. Nanocomposites are typically formed by the organization of nanoparticles within a polymeric matrix. However, this approach can lead to high organic fractions and phase separation; reducing the performance of themore » resulting material. Here, we form aminated nanoparticles that are then cross-linked using epoxy chemistry. The result is a magnetic nanoparticle component that is covalently linked and well separated. By using this ‘matrix-free’ approach, we can substantially increase the magnetic nanoparticle fraction, while still maintaining good separation, leading to a superparamagnetic nanocomposite with strong magnetic properties.« less

Gram scale synthesis of Fe/Fe xO y core–shell nanoparticles and their incorporation into matrix-free superparamagnetic nanocomposites

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

Watt, John Daniel; Bleier, Grant C.; Romero, Zachary William

In this paper, significant reductions recently seen in the size of wide-bandgap power electronics have not been accompanied by a relative decrease in the size of the corresponding magnetic components. To achieve this, a new generation of materials with high magnetic saturation and permeability are needed. Here, we develop gram-scale syntheses of superparamagnetic Fe/Fe xO y core–shell nanoparticles and incorporate them as the magnetic component in a strongly magnetic nanocomposite. Nanocomposites are typically formed by the organization of nanoparticles within a polymeric matrix. However, this approach can lead to high organic fractions and phase separation; reducing the performance of themore » resulting material. Here, we form aminated nanoparticles that are then cross-linked using epoxy chemistry. The result is a magnetic nanoparticle component that is covalently linked and well separated. By using this ‘matrix-free’ approach, we can substantially increase the magnetic nanoparticle fraction, while still maintaining good separation, leading to a superparamagnetic nanocomposite with strong magnetic properties.« less

Preparation of starch nanoparticles in water in oil microemulsion system and their drug delivery properties.

PubMed

Wang, Xinge; Chen, Haiming; Luo, Zhigang; Fu, Xiong

2016-03-15

In this research, 1-hexadecyl-3-methylimidazolium bromide C16mimBr/butan-1-ol/cyclohexane/water ionic liquid microemulsion was prepared. The effects of n-alkyl alcohols, alkanes, water content and temperature on the properties of microemulsion were studied by dilution experiment. The microregion of microemulsion was identified by pseudo-ternary phase diagram and conductivity measurement. Then starch nanoparticles were prepared by water in oil (W/O) microemulsion-cross-linking methods with C16mimBr as surfactant. Starch nanoparticles with a mean diameter of 94.3nm and narrow size distribution (SD=3.3) were confirmed by dynamic light scattering (DLS). Scanning electron microscope (SEM) data revealed that starch nanoparticles were spherical granules with the size about 60nm. Moreover the results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) demonstrated the formation of cross-linking bonds in starch molecules. Finally, the drug loading and releasing properties of starch nanoparticles were investigated with methylene blue (MB) as drug model. This work may provide an efficient pathway to synthesis starch nanoparticles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Three-dimensional cross-linking composite of graphene, carbon nanotubes and Si nanoparticles for lithium ion battery anode

NASA Astrophysics Data System (ADS)

Tian, Suyun; Zhu, Guannan; Tang, Yanping; Xie, Xiaohua; Wang, Qian; Ma, Yufei; Ding, Guqiao; Xie, Xiaoming

2018-03-01

Various graphene-based Si nanocomposites have been reported to improve the performance of active materials in Li-ion batteries. However, these candidates still yield severe capacity fading due to the electrical disconnection and fractures caused by the huge volume changes over extended cycles. Therefore, we have designed a novel three-dimensional cross-linked graphene and single-wall carbon nanotube structure to encapsulate the Si nanoparticles. The synthesized three-dimensional structure is attributed to the excellent self-assembly of carbon nanotubes with graphene oxide as well as a thermal treatment process at 900 °C. This special structure provides sufficient void spaces for the volume expansion of Si nanoparticles and channels for the diffusion of ions and electrons. In addition, the cross-linking of the graphene and single-wall carbon nanotubes also strengthens the stability of the structure. As a result, the volume expansion of the Si nanoparticles is restrained. The specific capacity remains at 1450 mAh g-1 after 100 cycles at 200 mA g-1. This well-defined three-dimensional structure facilitates superior capacity and cycling stability in comparison with bare Si and a mechanically mixed composite electrode of graphene, single-wall carbon nanotubes and silicon nanoparticles.

NIR-assisted orchid virus therapy using urchin bimetallic nanomaterials in phalaenopsis

NASA Astrophysics Data System (ADS)

Chen, Shin-Yu; Cheng, Liang-Chien; Chen, Chieh-Wei; Lee, Po-Han; Yu, Fengjiao; Zhou, Wuzong; Liu, Ru-Shi; Do, Yi-Yin; Huang, Pung-Ling

2013-12-01

The use of nanoparticles has drawn special attention, particularly in the treatment of plant diseases. Cymbidium mosaic virus (CymMV) and Odontoglossum ring spot virus (ORSV) are the most prevalent and serious diseases that affect the development of the orchid industry. In this study we treated nanoparticles as a strategy for enhancing the resistance of orchids against CymMV and ORSV. After chitosan-modified gold nanoparticles (Au NPs) were injected into Phalaenopsis leaves, the injected leaves were exposed to 980 nm laser for light-heat conversion. To evaluate virus elimination in the treated Phalaenopsis leaves, the transcripts of coat protein genes and the production of viral proteins were assessed by reverse transcription-Polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The expression of coat protein genes for both CymMV and ORSV was significantly lower in the chitosan-modified Au NP-treated Phalaenopsis leaves than in the control. Similarly, the amount of coat proteins for both viruses in the Phalaenopsis leaves was lower than that in the control (without nanoparticle injection). We propose that the temperature increase in the chitosan-modified Au NP-treated Phalaenopsis tissues after laser exposure reduces the viral population, consequently conferring resistance against CymMV and ORSV. Our findings suggest that the application of chitosan-modified Au NPs is a promising new strategy for orchid virus therapy.

In vivo evidence of oral vaccination with PLGA nanoparticles containing the immunostimulant monophosphoryl lipid A.

PubMed

Sarti, Federica; Perera, Glen; Hintzen, Fabian; Kotti, Katerina; Karageorgiou, Vassilis; Kammona, Olga; Kiparissides, Costas; Bernkop-Schnürch, Andreas

2011-06-01

Although oral vaccination has numerous advantages over the commonly used parenteral route, degradation of vaccine and its low uptake in the lymphoid tissue of the gastrointestinal (GI) tract still impede their development. In this study, the model antigen ovalbumin (OVA) and the immunostimulant monophosphoryl lipid A (MPLA) were incorporated in polymeric nanoparticles based on poly(D,L-lactide-co-glycolide) (PLGA). These polymeric carriers were orally administered to BALB/c mice (Bagg albino, inbred strain of mouse) and the resulting time-dependent systemic and mucosal immune responses towards OVA were assessed by measuring the OVA-specific IgG and IgA titers using an enzyme-linked immunosorbent assay (ELISA). PLGA nanoparticles were spherical in shape, around 320 nm in size, negatively charged (around -20 mV) and had an OVA and MPLA payload of 9.6% and 0.86%, respectively. A single immunization with formulation containing (OVA + MPLA) incorporated in PLGA nanoparticles induced a stronger IgG immune response than that induced by OVA in PBS solution or OVA incorporated into PLGA nanoparticles. Moreover, significantly higher IgA titers were generated by administration of (OVA + MPLA)/PLGA nanoparticles compared to IgA stimulated by control formulations, proving the capability of inducing a mucosal immunity. These findings demonstrate that co-delivery of OVA and MPLA in PLGA nanoparticles promotes both systemic and mucosal immune responses and represents therefore a suitable strategy for oral vaccination. Copyright © 2011 Elsevier Ltd. All rights reserved.

Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble.

PubMed

Koski, Jason P; Riggleman, Robert A

2017-04-28

Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (nVγT) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our nVγT approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the nVγT ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

Cytocompatible antifungal acrylic resin containing silver nanoparticles for dentures

PubMed Central

Acosta-Torres, Laura Susana; Mendieta, Irasema; Nuñez-Anita, Rosa Elvira; Cajero-Juárez, Marcos; Castaño, Víctor M

2012-01-01

Background Inhibition of Candida albicans on denture resins could play a significant role in preventing the development of denture stomatitis. The safety of a new dental material with antifungal properties was analyzed in this work. Methods Poly(methyl methacrylate) [PMMA] discs and PMMA-silver nanoparticle discs were formulated, with the commercial acrylic resin, Nature-CrylTM, used as a control. Silver nanoparticles were synthesized and characterized by ultraviolet-visible spectroscopy, dispersive Raman spectroscopy, and transmission electron microscopy. The antifungal effect was assessed using a luminescent microbial cell viability assay. Biocompatibility tests were carried out using NIH-3T3 mouse embryonic fibroblasts and a Jurkat human lymphocyte cell line. Cells were cultured for 24 or 72 hours in the presence or absence of the polymer formulations and analyzed using three different tests, ie, cellular viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and cell proliferation by enzyme-linked immunosorbent assay BrdU, and genomic DNA damage (Comet assay). Finally, the samples were evaluated mechanically, and the polymer-bearing silver nanoparticles were analyzed microscopically to evaluate dispersion of the nanoparticles. Results The results show that PMMA-silver nanoparticle discs significantly reduce adherence of C. albicans and do not affect metabolism or proliferation. They also appear not to cause genotoxic damage to cells. Conclusion The present work has developed a new biocompatible antifungal PMMA denture base material. PMID:22969297

Fabrication of submicron structures in nanoparticle/polymer composite by holographic lithography and reactive ion etching

NASA Astrophysics Data System (ADS)

Zhang, A. Ping; He, Sailing; Kim, Kyoung Tae; Yoon, Yong-Kyu; Burzynski, Ryszard; Samoc, Marek; Prasad, Paras N.

2008-11-01

We report on the fabrication of nanoparticle/polymer submicron structures by combining holographic lithography and reactive ion etching. Silica nanoparticles are uniformly dispersed in a (SU8) polymer matrix at a high concentration, and in situ polymerization (cross-linking) is used to form a nanoparticle/polymer composite. Another photosensitive SU8 layer cast upon the nanoparticle/SU8 composite layer is structured through holographic lithography, whose pattern is finally transferred to the nanoparticle/SU8 layer by the reactive ion etching process. Honeycomb structures in a submicron scale are experimentally realized in the nanoparticle/SU8 composite.

Cytoprotective nanoparticles by conjugation of a polyhis tagged annexin V to a nanoparticle drug.

PubMed

Chen, Howard H; Yuan, Hushan; Cho, Hoonsung; Sosnovik, David E; Josephson, Lee

2015-02-14

We synthesized a cytoprotective magnetic nanoparticle by reacting a maleimide functionalized Feraheme (FH) with a disulfide linked dimer of a polyhis tagged annexin V. Following reductive cleavage of disulfide, the resulting annexin-nanoparticle (diameter = 28.0 ± 2.0 nm by laser light scattering, 7.6 annexin's/nanoparticle) was cytoprotective to cells subjected to plasma membrane disrupting chemotherapeutic or mechanical stresses, and significantly more protective than the starting annexin V. Annexin-nanoparticles provide an approach to the design of nanomaterials which antagonize the plasma membrane permeability characteristic of necrosis and which may have applications as cytoprotective agents.

From nano- to macro-engineering of oxide-encapsulated-nanoparticles for harsh reactions: one-step organization via cross-linking molecules.

PubMed

Zhang, Qiaofei; Zhao, Guofeng; Zhang, Zhiqiang; Han, Lupeng; Fan, Songyu; Chai, Ruijuan; Li, Yakun; Liu, Ye; Huang, Jun; Lu, Yong

2016-09-29

A strategy of "macro-micro-nano" organization is reported for embedding oxide-encapsulated-nanoparticles onto monolithic substrates in one-step with the aid of molecularly defined cross-linking agents. Such catalysts, with enhanced heat/mass transfer and high permeability, are qualified for several harsh reaction processes such as CH 4 /VOC abatement, gas-phase hydrogenation of dimethyl oxalate and oxidative dehydrogenation of ethane.

Rheological behavior of clay-nanoparticle hybrid-added bentonite suspensions: specific role of hybrid additives on the gelation of clay-based fluids.

PubMed

Jung, Youngsoo; Son, You-Hwan; Lee, Jung-Kun; Phuoc, Tran X; Soong, Yee; Chyu, Minking K

2011-09-01

Two different types of clay nanoparticle hybrid, iron oxide nanoparticle clay hybrid (ICH) and Al(2)O(3)-SiO(2) nanoparticle clay hybrid (ASCH), were synthesized and their effects on the rheological properties of aqueous bentonite fluids in steady state and dynamic state were explored. When ICH particles were added, bentonite particles in the fluid cross-link to form relatively well-oriented porous structure. This is attributed to the development of positively charged edge surfaces in ICH that leads to strengthening of the gel structure of the bentonite susensions. The role of ASCH particles on the interparticle association of the bentonite fluids is different from that of ICH and sensitive to pH. As pH of ASCH-added bentonite suspensions increased, the viscosity, yield stress, storage modulus, and flow stress decreased. In contrast, at low pH, the clay suspensions containing ASCH additives were coagulated and their rheological properties become close to those of ICH added bentonite fluids. A correlation between the net surface charge of the hybrid additives and the rheological properties of the fluids indicates that the embedded nanoparticles within the interlayer space control the variable charge of the edge surfaces of the platelets and determine the particles association behavior of the clay fluids.

Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

PubMed Central

Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

2016-01-01

Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures. PMID:27189842

Tailored functionalization of iron oxide nanoparticles for MRI, drug delivery, magnetic separation and immobilization of biosubstances.

PubMed

Hola, Katerina; Markova, Zdenka; Zoppellaro, Giorgio; Tucek, Jiri; Zboril, Radek

2015-11-01

In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging. Copyright © 2015 Elsevier Inc. All rights reserved.

DNA Assembly Line for Nano-Construction

ScienceCinema

Oleg Gang

2017-12-09

Building on the idea of using DNA to link up nanoparticles scientists at Brookhaven National Lab have designed a molecular assembly line for high-precision nano-construction. Nanofabrication is essential for exploiting the unique properties of nanoparticl

Multi-stimuli-responsive biohybrid nanoparticles with cross-linked albumin coronae self-assembled by a polymer-protein biodynamer.

PubMed

Wang, Lin; Liu, Li; Dong, Bingyang; Zhao, Hanying; Zhang, Mingming; Chen, Wenjuan; Hong, Yanhang

2017-05-01

A thermoresponsive polymer-protein biodynamer was prepared via the bioconjugation of an aliphatic aldehyde-functionalized copolymer to hydrazine-modified bovine serum albumin (BSA) through reversible pyridylhydrazone linkages. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography (SEC) results indicated that the pyridylhydrazone linkages cleaved in an intracellular-mimicking acidic milieu, thus leading to the release of BSA. The dynamic character of the protein biodynamer was demonstrated by exchange reactions with aldehyde-containing molecules. The biodynamer self-assembled into spherical micelles at a temperature above its lower critical solution temperature (LCST). Subsequently, BSA molecules within the hydrophilic coronae of the micelles were readily cross-linked via reaction with cystamine at 45°C, and multi-stimuli-responsive nanoparticles were generated. The biohybrid nanoparticles reversibly swelled and shrank as the cores of the nanoparticles were solvated below the LCST and desolvated above the LCST. The accessible reversibility of the pyridylhydrazone bonds imparts pH-responsive and dynamic characteristics to the nanoparticles. The nanoparticles displayed glutathione (GSH) responsiveness, and the synergistic effects of pH and GSH resulted in complete disintegration of the nanoparticles under the intracellular-mimicking acidic and reductive conditions. The nanoparticles were also enzyme-responsive and disintegrated rapidly in the presence of protease. In vitro cytotoxicity and cell uptake assays demonstrated that the nanoparticles were highly biocompatible and effectively internalized by HepG2 cells, which make them interesting candidates as vehicles for drug delivery application and biomimetic platforms to investigate the biological process in nature. In this research, we report the synthesis of a temperature and pH dual-responsive polymer-protein biodynamer through reversible pyridylhydrazone formation. The prepared biodynamer can offer a potential platform for intracellular protein delivery. The multi-stimuli-responsive biohybrid nanoparticles containing disulfide functionalities are constructed by cross-linking albumin coronae of the biodynamer micelles. With the combination of a thermoresponsive polymer, protein and reversible covalent bonds, the biohybrid nanoparticles are endowed with highly biocompatible, environmentally responsive and adaptive features. These nanoparticles present the ability to undergo changes in their constitution, hydrodynamic size and nanostructure in response to physical, chemical and biological stimuli, which make them interesting candidates as vehicles for drug delivery application and a biomimetic platform to investigate the biological process in nature. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Controlled release of bioactive PDGF-AA from a hydrogel/nanoparticle composite.

PubMed

Elliott Donaghue, Irja; Shoichet, Molly S

2015-10-01

Polymer excipients, such as low molar mass poly(ethylene glycol) (PEG), have shown contradictory effects on protein stability when co-encapsulated in polymeric nanoparticles. To gain further insight into these effects, platelet-derived growth factor (PDGF-AA) was encapsulated in polymeric nanoparticles with vs. without PEG. PDGF-AA is a particularly compelling protein, as it has been demonstrated to promote cell survival and induce the oligodendrocyte differentiation of neural stem/progenitor cells (NSPCs) both in vitro and in vivo. Here we show, for the first time, the controlled release of bioactive PDGF-AA from an injectable nanoparticle/hydrogel drug delivery system (DDS). PDGF-AA was encapsulated, with high efficiency, in poly(lactide-co-glycolide) nanoparticles, and its release from the drug delivery system was followed over 21 d. Interestingly, the co-encapsulation of low molecular weight poly(ethylene glycol) increased the PDGF-AA loading but, unexpectedly, accelerated the aggregation of PDGF-AA, resulting in reduced activity and detection by enzyme-linked immunosorbent assay (ELISA). In the absence of PEG, released PDGF-AA remained bioactive as demonstrated with NSPC oligodendrocyte differentiation, similar to positive controls, and significantly different from untreated controls. This work presents a novel delivery method for differentiation factors, such as PDGF-AA, and provides insights into the contradictory effects reported in the literature of excipients, such as PEG, on the loading and release of proteins from polymeric nanoparticles. Previously, the polymer poly(ethylene glycol) (PEG) has been used in many biomaterials applications, from surface coatings to the encapsulation of proteins. In this work, we demonstrate that, unexpectedly, low molecular weight PEG has a deleterious effect on the release of the encapsulated protein platelet-derived growth factor AA (PDGF-AA). We also demonstrate release of bioactive PDGF-AA (in the absence of PEG). Specifically, we demonstrate the differentiation of neural stem and progenitor cells to oligodendrocytes, similar to what is observed with the addition of fresh PDGFAA. A differentiated oligodendrocyte population is a key strategy in central nervous system regeneration. This work is the first demonstration of controlled PDGF-AA release, and also brings new insights to the broader field of protein encapsulation. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Optimization of the fabrication of novel stealth PLA-based nanoparticles by dispersion polymerization using D-optimal mixture design.

PubMed

Adesina, Simeon K; Wight, Scott A; Akala, Emmanuel O

2014-11-01

Nanoparticle size is important in drug delivery. Clearance of nanoparticles by cells of the reticuloendothelial system has been reported to increase with increase in particle size. Further, nanoparticles should be small enough to avoid lung or spleen filtering effects. Endocytosis and accumulation in tumor tissue by the enhanced permeability and retention effect are also processes that are influenced by particle size. We present the results of studies designed to optimize cross-linked biodegradable stealth polymeric nanoparticles fabricated by dispersion polymerization. Nanoparticles were fabricated using different amounts of macromonomer, initiators, crosslinking agent and stabilizer in a dioxane/DMSO/water solvent system. Confirmation of nanoparticle formation was by scanning electron microscopy (SEM). Particle size was measured by dynamic light scattering (DLS). D-optimal mixture statistical experimental design was used for the experimental runs, followed by model generation (Scheffe polynomial) and optimization with the aid of a computer software. Model verification was done by comparing particle size data of some suggested solutions to the predicted particle sizes. Data showed that average particle sizes follow the same trend as predicted by the model. Negative terms in the model corresponding to the cross-linking agent and stabilizer indicate the important factors for minimizing particle size.

Supramolecular domains in mixed peptide self-assembled monolayers on gold nanoparticles.

PubMed

Duchesne, Laurence; Wells, Geoff; Fernig, David G; Harris, Sarah A; Lévy, Raphaël

2008-09-01

Self-organization in mixed self-assembled monolayers of small molecules provides a route towards nanoparticles with complex molecular structures. Inspired by structural biology, a strategy based on chemical cross-linking is introduced to probe proximity between functional peptides embedded in a mixed self-assembled monolayer at the surface of a nanoparticle. The physical basis of the proximity measurement is a transition from intramolecular to intermolecular cross-linking as the functional peptides get closer. Experimental investigations of a binary peptide self-assembled monolayer show that this transition happens at an extremely low molar ratio of the functional versus matrix peptide. Molecular dynamics simulations of the peptide self-assembled monolayer are used to calculate the volume explored by the reactive groups. Comparison of the experimental results with a probabilistic model demonstrates that the peptides are not randomly distributed at the surface of the nanoparticle, but rather self-organize into supramolecular domains.

Formation mechanism of monodispersed spherical core-shell ceria/polymer hybrid nanoparticles

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

Izu, Noriya, E-mail: n-izu@aist.go.jp; Uchida, Toshio; Matsubara, Ichiro

2011-08-15

Graphical abstract: The formation mechanism for core-shell nanoparticles is considered to be as follows: nucleation and particle growth occur simultaneously (left square); very slow particle growth occurs (middle square). Highlights: {yields} The size of the resultant nanoparticles was strongly and complicatedly dependent on the set temperature used during reflux heating and the PVP molecular weight. {yields} The size of the nanoparticles increased by a 2-step process as the reflux heating time increased. {yields} The IR spectral changes with increasing reflux time indicated the increase in the number of cross-linked polymers in the shell. -- Abstract: Very unique core-shell ceria (ceriummore » oxide)/polymer hybrid nanoparticles that have monodispersed spherical structures and are easily dispersed in water or alcohol without the need for a dispersant were reported recently. The formation mechanism of the unique nanoparticles, however, was not clear. In order to clarify the formation mechanism, these nanoparticles were prepared using a polyol method (reflux heating) under varied conditions of temperature, time, and concentration and molecular weight of added polymer (poly(vinylpyrrolidone)). The size of the resultant nanoparticles was strongly and complicatedly dependent on the set temperature used during reflux heating and the poly(vinylpyrrolidone) molecular weight. Furthermore, the size of the nanoparticles increased by a 2-step process as the reflux heating time increased. The IR spectral changes with increasing reflux time indicated the increase in the number of cross-linked polymers in the shell. From these results, the formation mechanism was discussed and proposed.« less

PEGylated human serum albumin (HSA) nanoparticles: preparation, characterization and quantification of the PEGylation extent

NASA Astrophysics Data System (ADS)

Fahrländer, E.; Schelhaas, S.; Jacobs, A. H.; Langer, K.

2015-04-01

Modification with poly(ethylene glycol) (PEG) is a widely used method for the prolongation of plasma half-life of colloidal carrier systems such as nanoparticles prepared from human serum albumin (HSA). However, the quantification of the PEGylation extent is still challenging. Moreover, the influence of different PEG derivatives, which are commonly used for nanoparticle conjugation, has not been investigated so far. The objective of the present study is to develop a method for the quantification of PEG and to monitor the influence of diverse PEG reagents on the amount of PEG linked to the surface of HSA nanoparticles. A size exclusion chromatography method with refractive index detection was established which enabled the quantification of unreacted PEG in the supernatant. The achieved results were confirmed using a fluorescent PEG derivative, which was detected by photometry and fluorimetry. Additionally, PEGylated HSA nanoparticles were enzymatically digested and the linked amount of fluorescently active PEG was directly determined. All the analytical methods confirmed that under optimized PEGylation conditions a PEGylation efficiency of up to 0.5 mg PEG per mg nanoparticle could be achieved. Model calculations made a ‘brush’ conformation of the PEG chains on the particle surface very likely. By incubating the nanoparticles with fetal bovine serum the reduced adsorption of serum proteins on PEGylated HSA nanoparticles compared to non-PEGylated HSA nanoparticles was demonstrated using sodium dodecylsulfate polyacrylamide gel electrophoresis. Finally, the positive effect of PEGylation on plasma half-life was demonstrated in an in vivo study in mice. Compared to unmodified nanoparticles the PEGylation led to a four times larger plasma half-life.

Measuring and controlling the transport of magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Stephens, Jason R.

Despite the large body of literature describing the synthesis of magnetic nanoparticles, few analytical tools are commonly used for their purification and analysis. Due to their unique physical and chemical properties, magnetic nanoparticles are appealing candidates for biomedical applications and analytical separations. Yet in the absence of methods for assessing and assuring their purity, the ultimate use of magnetic particles and heterostructures is likely to be limited. For magnetic nanoparticles, it is the use of an applied magnetic flux or field gradient that enables separations. Flow based techniques are combined with applied magnetic fields to give methods such as magnetic field flow fractionation and high gradient magnetic separation. Additional techniques have been explored for manipulating particles in microfluidic channels and in mesoporous membranes. This thesis further describes development of these and new analytical tools for separation and analysis of colloidal particles is critically important to enable the practical use of these, particularly for medicinal purposes. Measurement of transport of nanometer scale particles through porous media is important to begin to understand the potential environmental impacts of nanomaterials. Using a diffusion cell with two compartments separated by either a porous alumina or polycarbonate membrane as a model system, diffusive flux through mesoporous materials is examined. Experiments are performed as a function of particle size, pore diameter, and solvent, and the particle fluxes are monitored by the change in absorbance of the solution in the receiving cell. Using the measured extinction coefficient and change in absorbance of the solution as a function of time, the fluxes of 3, 8, and 14 nm diameter CoFe2O4 particles are determined as they are translocated across pores with diameters 30, 50, 100, and 200 nm in hexane and aqueous solutions. In general, flux decreases with increasing particle size and increases with pore diameter. We find that fluxes are faster in aqueous solutions than in hexane, which is attributed to the hydrophilic nature of the porous membranes and differences in wettability. The impact of an applied magnetic flux gradient, which induces magnetization and motion, on permeation is also examined. Surface chemistry plays an important role in determining flux through porous media such as in the environment. Diffusive flux of nanoparticles through alkylsilane modified porous alumina is measured as a model for understanding transport in porous media of differing surface chemistries. Experiments are performed as a function of particle size, pore diameter, attached hydrocarbon chain length and chain terminus, and solvent. Particle fluxes are monitored by the change in absorbance of the solution in the receiving side of a diffusion cell. In general, flux increases when the membranes are modified with alkylsilanes compared to untreated membranes, which is attributed to the hydrophobic nature of the porous membranes and differences in wettability. We find that flux decreases, in both hexane and aqueous solutions, when the hydrocarbon chain lining the interior pore wall increases in length. The rate and selectivity of transport across these membranes is related to the partition coefficient (Kp) and the diffusion coefficient (D) of the permeating species. By conducting experiments as a function of initial particle concentration, we find that KpD increases with increasing particle size, is greater in alkylsilane--modified pores, and larger in hexane solution than water. The impact of the alkylsilane terminus (--CH3, --Br, --NH2, --COOH) on permeation in water is also examined. In water, the highest KpD is observed when the membranes are modified with carboxylic acid terminated silanes and lowest with amine terminated silanes as a result of electrostatic effects during translocation. Finally, the manipulation of magnetic nanoparticles for the controlled formation of linked nanoparticle assemblies between microfluidic channels by the application of an external magnet is discussed. Two orthogonal channels were prepared using standard PDMS techniques with pressure-driven flow used to deliver the Fe3O4 and Au nanoparticle reactants. Nanoparticle assembly formation is based upon locally confined surface modification of Fe3O4 nanoparticles interacting with Au nanoparticles bridging the two particles together. For the magnetic particles, transfer between flow streams is greatly increased by placing a permanent magnet above and below the channel intersections. Multiple configurations of Fe3O 4 and Au nanoparticle assemblies are observed as a function of flow rate and interaction time of the individual nanoparticle components. We observe the formation of higher order assemblies by increasing the concentration of Fe3O4 nanoparticles introduced to the microfluidic device. This technique demonstrates the ability to form nanoparticle linked assemblies and could be easily linked to other analytical techniques developed in our lab to further isolate and separate a particular product. (Abstract shortened by UMI.)

Adsorption of environmental pollutants using magnetic hybrid nanoparticles modified with β-cyclodextrin

NASA Astrophysics Data System (ADS)

Wang, Niejun; Zhou, Lilin; Guo, Jun; Ye, Qiquan; Lin, Jin-Ming; Yuan, Jinying

2014-06-01

Graft through strategy was utilized to coat magnetic Fe3O4 nanoparticles with poly(glycidyl methacrylate) using ordinary radical polymerization and then β-cyclodextrin was linked onto the surface of nanoparticles. With these nanoparticles modified with cyclodextrin groups, adsorption of two model environmental pollutants, bisphenol A and copper ions, was studied. Host-guest interactions between cyclodextrin and aromatic molecules had a great contribution to the adsorption of bisphenol A, while multiple hydroxyls of cyclodextrin also helped the adsorption of copper ions. These magnetic nanoparticles could be applied in the elimination, enrichment and detection of some environmental pollutants.

A highly sensitive and selective diagnostic assay based on virus nanoparticles

NASA Astrophysics Data System (ADS)

Park, Jin-Seung; Cho, Moon Kyu; Lee, Eun Jung; Ahn, Keum-Young; Lee, Kyung Eun; Jung, Jae Hun; Cho, Yunjung; Han, Sung-Sik; Kim, Young Keun; Lee, Jeewon

2009-04-01

Early detection of the protein marker troponin I in patients with a higher risk of acute myocardial infarction can reduce the risk of death from heart attacks. Most troponin assays are currently based on the conventional enzyme linked immunosorbent assay and have detection limits in the nano- and picomolar range. Here, we show that by combining viral nanoparticles, which are engineered to have dual affinity for troponin antibodies and nickel, with three-dimensional nanostructures including nickel nanohairs, we can detect troponin levels in human serum samples that are six to seven orders of magnitude lower than those detectable using conventional enzyme linked immunosorbent assays. The viral nanoparticle helps to orient the antibodies for maximum capture of the troponin markers. High densities of antibodies on the surfaces of the nanoparticles and nanohairs lead to greater binding of the troponin markers, which significantly enhances detection sensitivities. The nickel nanohairs are re-useable and can reproducibly differentiate healthy serum from unhealthy ones. We expect other viral nanoparticles to form similar highly sensitive diagnostic assays for a variety of other protein markers.

In Vitro and In Vivo Toxicity Evaluation of Colloidal Silver Nanoparticles Used in Endodontic Treatments.

PubMed

Takamiya, Aline Satie; Monteiro, Douglas Roberto; Bernabé, Daniel Galera; Gorup, Luiz Fernando; Camargo, Emerson Rodrigues; Gomes-Filho, João Eduardo; Oliveira, Sandra Helena Penha; Barbosa, Debora Barros

2016-06-01

Silver nanoparticles have been used for different purposes in dentistry, including endodontic treatments. The aim of this study was to determine the cytotoxicity of different types of silver nanoparticles on mouse fibroblast cell line L929 and the reaction of subcutaneous connective tissue of Wistar rats to these nanoparticles. Silver nanoparticles of an average size of 5 nm were synthesized with ammonia (SNA) or polyvinylpyrrolidone (SNP). L929 was exposed to SNA and SNP (0.1-100 μg/mL), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and enzyme-linked immunosorbent assays were performed after 6, 24, and 48 hours. Culture medium was used as the control. Sixteen rats received, individually, 3 polyethylene tubes filled with a fibrin sponge embedded in 100 μL SNA or SNP (1 μg/mL). A fibrin sponge with no embedding was the control. Tissue reaction was performed qualitatively and quantitatively after 7, 15, 30, and 90 days of implantation in the dorsal connective tissue of Wistar rats. SNA and SNP were cytotoxic to L929 in higher concentrations, with SNA significantly more toxic than SNP. SNA and SNP did not induce significant interleukin-1β and interleukin-6 production. The release of stem cell factor by L929 increased 48 hours after the treatment with SNP at 5 μg/mL. Histologic examination showed that the inflammatory responses caused by SNA and SNP at 1 μg/mL were similar to the control in all experimental periods. It was concluded that SNA and SNP were not cytotoxic at 25 μg/mL or lower concentrations. However, for safe clinical use, further studies establishing others points of its toxicologic profile are recommended. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Toward a modular multi-material nanoparticle synthesis and assembly strategy via bionanocombinatorics: bifunctional peptides for linking Au and Ag nanomaterials

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

Briggs, Beverly D.; Palafox-Hernandez, J. Pablo; Li, Yue

Materials-binding peptides represent a unique avenue towards controlling the shape and size of nanoparticles (NPs) grown under aqueous conditions. Here, employing a bionanocombinatorics approach, two such materials-binding peptides were linked at either end of a photoswitchable spacer, forming a multi-domain materials-binding molecule to control the in situ synthesis and organization of Ag and Au NPs under ambient conditions. These multi-domain molecules retained the peptides’ ability to nucleate, grow, and stabilize Ag and Au NPs in aqueous media. Disordered co-assemblies of the two nanomaterials were observed by TEM imaging of dried samples after sequential growth of the two metals, and showedmore » a clustering behavior that was not observed without both metals and the linker molecules. While TEM evidence indicated the formation of AuNP/AgNP assemblies upon drying, SAXS analysis indicated that no extended assemblies existed in solution, suggesting that sample drying plays an important role in facilitating NP clustering. Molecular simulations and experimental data revealed tunable materials-binding based upon the isomerization state of the photoswitchable unit and metal employed. This work is a first step in generating externally actuated biomolecules with specific material-binding properties that could be used as the building blocks to achieve multi-material switchable NP assemblies.« less

Endostar-loaded PEG-PLGA nanoparticles: in vitro and in vivo evaluation.

PubMed

Hu, Sanyuan; Zhang, Yangde

2010-11-24

Endostar, a novel recombinant human endostatin, which was approved by the Chinese State Food and Drug Administration in 2005, has a broad spectrum of activity against solid tumors. In this study, we aimed to determine whether the anticancer effect of Endostar is increased by using a nanocarrier system. It is expected that the prolonged circulation of endostar will improve its anticancer activity. Endostar-loaded nanoparticles were prepared to improve controlled release of the drug in mice and rabbits, as well as its anticancer effects in mice with colon cancer. A protein release system could be exploited to act as a drug carrier. Nanoparticles were formulated from poly (ethylene glycol) modified poly (DL-lactide-co-glycolide) (PEG-PLGA) by a double emulsion technique. Physical and release characteristics of endostar-loaded nanoparticles in vitro were evaluated by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and micro bicinchoninic acid protein assay. The pharmacokinetic parameters of endostar nanoparticles in rabbit and mice plasma were measured by enzyme-linked immunosorbent assay. Western blot was used to detect endostatin in different tissues. To study the effects of endostar-loaded nanoparticles in vivo, nude mice in which tumor cells HT-29 were implanted, were subsequently treated with endostar or endostar-loaded PEG-PLGA nanoparticles. Using TEM and PCS, endostar-loaded PEG-PLGA nanoparticles were found to have a spherical core-shell structure with a diameter of 169.56 ± 35.03 nm. Drug-loading capacity was 8.22% ± 2.35% and drug encapsulation was 80.17% ± 7.83%. Compared with endostar, endostar-loaded PEG-PLGA nanoparticles had a longer elimination half-life and lower peak concentration, caused slower growth of tumor cell xenografts, and prolonged tumor doubling times. The nanoparticles changed the pharmacokinetic characteristics of endostar in mice and rabbits, thereby reinforcing anticancer activity. In conclusion, PEG-PLGA nanoparticles are a feasible carrier for endostar. Endostar-loaded PEG-PLGA nanoparticles seem to have a better anticancer effect than conventional endostar. We believe that PEG-PLGA nanoparticles are an effective carrier for protein medicines.

Mesoporous silica nanoparticle-based intelligent drug delivery system for bienzyme-responsive tumour targeting and controlled release.

PubMed

Zhang, Yang; Xu, Juan

2018-01-01

This paper proposes a novel type of multifunctional envelope-type mesoporous silica nanoparticle (MSN) to achieve cancer cell targeting and drug-controlled release. In this system, MSNs were first modified by active targeting moiety hyaluronic acid (HA) for breast cancer cell targeting and hyaluronidases (Hyal)-induced intracellular drug release. Then gelatin, a proteinaceous biopolymer, was grafted onto the MSNs to form a capping layer via glutaraldehyde-mediated cross-linking. To shield against unspecific uptake of cells and prolong circulation time, the nanoparticles were further decorated with poly(ethylene glycol) polymers (PEG) to obtain MSN@HA-gelatin-PEG (MHGP). Doxorubicin (DOX), as a model drug, was loaded into PEMSN to assess the breast cancer cell targeting and drug release behaviours. In vitro study revealed that PEG chains protect the targeting ligand and shield against normal cells. After reaching the breast cancer cells, MMP-2 overpressed by cells hydrolyses gelatin layer to deshield PEG and switch on the function of HA. As a result, DOX-loaded MHGP was selectively trapped by cancer cells through HA receptor-mediated endocytosis and subsequently release DOX due to Hyal-catalysed degradation of HA. This system presents successful bienzyme-responsive targeting drug delivery in an optimal fashion and provides potential applications for targeted cancer therapy.

Intranasal immunization with chitosan/pCETP nanoparticles inhibits atherosclerosis in a rabbit model of atherosclerosis.

PubMed

Yuan, Xiying; Yang, Xiaorong; Cai, Danning; Mao, Dan; Wu, Jie; Zong, Li; Liu, Jingjing

2008-07-04

In search of a convenient and pain-free route of administration of DNA vaccine against atherosclerosis, the plasmid pCR-X8-HBc-CETP (pCETP) encoding B-cell epitope of cholesteryl ester transfer protein C-terminal fragment displayed by Hepatitis B virus core particle was condensed with chitosan to form chitosan/pCETP nanoparticles. Cholesterol-fed rabbits were then intranasally immunized with the chitosan/pCETP nanoparticles to evaluate antiatherogenic effects. The results showed that significant serum antibodies against CETP were detected by enzyme-linked immunosorbent analysis and verified by Western blot analysis. The significant anti-CETP IgG lasted for 21 weeks in the rabbits immunized intranasally. Moreover, the atherogenic index was significantly lower compared with the saline control (5.95 versus 2.39, p<0.05). In addition, the average percentage of aortic lesions in the entire aorta area in the rabbits intranasally vaccinated with nanoparticles was 59.2% less than those treated with saline (29.0+/-10.9% versus 71.0+/-14.4%, p<0.01) and was similar to those intramuscularly injected with pCETP solution (29.0+/-10.9% versus 21.2+/-14.2%, p>0.05). Thus, chitosan/pCETP nanoparticles could significantly attenuate the progression of atherosclerosis by intranasal immunization. The results suggested that intranasal administration could be potentially developed as a vaccination route against atherosclerosis.

Targeted delivery of cisplatin to prostate cancer cells by aptamer functionalized Pt(IV) prodrug-PLGA-PEG nanoparticles.

PubMed

Dhar, Shanta; Gu, Frank X; Langer, Robert; Farokhzad, Omid C; Lippard, Stephen J

2008-11-11

Cisplatin is used to treat a variety of tumors, but dose limiting toxicities or intrinsic and acquired resistance limit its application in many types of cancer including prostate. We report a unique strategy to deliver cisplatin to prostate cancer cells by constructing Pt(IV)-encapsulated prostate-specific membrane antigen (PSMA) targeted nanoparticles (NPs) of poly(D,L-lactic-co-glycolic acid) (PLGA)-poly(ethylene glycol) (PEG)-functionalized controlled release polymers. By using PLGA-b-PEG nanoparticles with PSMA targeting aptamers (Apt) on the surface as a vehicle for the platinum(IV) compound c,t,c-[Pt(NH(3))(2)(O(2)CCH(2)CH(2)CH(2)CH(2)CH(3))(2)Cl(2)] (1), a lethal dose of cisplatin was delivered specifically to prostate cancer cells. PSMA aptamer targeted delivery of Pt(IV) cargos to PSMA(+) LNCaP prostate cancer cells by endocytosis of the nanoparticle vehicles was demonstrated using fluorescence microscopy by colocalization of green fluorescent labeled cholesterol-encapsulated NPs and early endosome marker EEA-1. The choice of linear hexyl chains in 1 was the result of a systematic study to optimize encapsulation and controlled release from the polymer without compromising either feature. Release of cisplatin from the polymeric nanoparticles after reduction of 1 and formation of cisplatin 1,2-intrastrand d(GpG) cross-links on nuclear DNA was confirmed by using a monoclonal antibody for the adduct. A comparison between the cytotoxic activities of Pt(IV)-encapsulated PLGA-b-PEG NPs with the PSMA aptamer on the surface (Pt-NP-Apt), cisplatin, and the nontargeted Pt(IV)-encapsulated NPs (Pt-NP) against human prostate PSMA-overexpressing LNCaP and PSMA(-) PC3 cancer cells revealed significant differences. The effectiveness of PSMA targeted Pt-NP-Apt nanoparticles against the PSMA(+) LNCaP cells is approximately an order of magnitude greater than that of free cisplatin.

Hybrid catechin silica nanoparticle influence on Cu(II) toxicity and morphological lesions in primary neuronal cells.

PubMed

Halevas, E; Nday, C M; Salifoglou, A

2016-10-01

Morphological alterations compromising inter-neuronal connectivity may be directly linked to learning-memory deficits in Central Nervous System neurodegenerative processes. Cu(II)-mediated oxidative stress plays a pivotal role in regulating redox reactions generating reactive oxygen species (ROS) and reactive nitrogen species (RNS), known contributors to Alzheimer's disease (AD) pathology. The antioxidant properties of flavonoid catechin have been well-documented in neurodegenerative processes. However, the impact that catechin encapsulation in nanoparticles may have on neuronal survival and morphological lesions has been poorly demonstrated. To investigate potential effects of nano-encapsulated catechin on neuronal survival and morphological aberrations in primary rat hippocampal neurons, poly(ethyleneglycol) (PEG) and cetyltrimethylammonium bromide (CTAB)-modified silica nanoparticles were synthesized. Catechin was loaded on silica nanoparticles in a concentration-dependent fashion, and release studies were carried out. Further physicochemical characterization of the new nano-materials included elemental analysis, particle size, z-potential, FT-IR, Brunauer-Emmett-Teller (BET), thermogravimetric (TGA), and scanning electron microscopy (SEM) analysis in order to optimize material composition linked to the delivery of loaded catechin in the hippocampal cellular milieu. The findings reveal that, under Cu(II)-induced oxidative stress, the loading ability of the PEGylated/CTAB silica nanoparticles was concentration-dependent, based on their catechin release profile. The overall bio-activity profile of the new hybrid nanoparticles a) denoted their enhanced protective activity against oxidative stress and hippocampal cell survival compared to previously reported quercetin, b) revealed that morphological lesions affecting neuronal integrity can be counterbalanced at high copper concentrations, and c) warrants in-depth perusal of molecular events underlying neuronal function and degeneration, collectively linked to preventive nanotechnology in neurodegeneration. Copyright © 2016 Elsevier Inc. All rights reserved.

Single chain technology: Toward the controlled synthesis of polymer nanostructures

NASA Astrophysics Data System (ADS)

Lyon, Christopher

A technique for fabricating advanced polymer nanostructures enjoying recent popularity is the collapse or folding of single polymer chains in highly dilute solution mediated by intramolecular cross-linking. We term the resultant structures single-chain nanoparticles (SCNP). This technique has proven particularly valuable in the synthesis of nanomaterials on the order of 5 -- 20 nm. Many different types of covalent and non-covalent chemistries have been used to this end. This dissertation investigates the use of so-called single-chain technology to synthesize nanoparticles using modular techniques that allow for easy incorporation of functionality or special structural or characteristic features. Specifically, the synthesis of linear polymers functionalized with pendant monomer units and the subsequent intramolecular polymerization of these monomer units is discussed. In chapter 2, the synthesis of SCNP using alternating radical polymerization is described. Polymers functionalized with pendant styrene and stilbene groups are synthesized via a modular post-polymerization Wittig reaction. These polymers were exposed to radical initiators in the presence (and absence) of maleic anhydride and other electron deficient monomers in order to form intramolecular cross-links. Chapter 3 discusses templated acyclic diene metathesis (ADMET) polymerization using single-chain technology, starting with the controlled ring-opening polymerization of a glycidyl ether functionalized with an ADMET monomer. This polymer was then exposed to Grubbs' catalyst to polymerize the ADMET monomer units. The ADMET polymer was hydrolytically cleaved from the template and separated. Upon characterization, it was found that the daughter ADMET polymer had a similar degree of polymerization, but did not retain the low dispersity of the template. Chapter 4 details the synthesis of aldehyde- and diol-functionalized polymers toward the synthesis of SCNP containing dynamic, acid-degradable acetal cross-links. SCNP fabrication with these materials is beyond the scope of this dissertation.

Red Fluorescent Carbon Nanoparticle-Based Cell Imaging Probe.

PubMed

Ali, Haydar; Bhunia, Susanta Kumar; Dalal, Chumki; Jana, Nikhil R

2016-04-13

Fluorescent carbon nanoparticle-based probes with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. However, synthesis of red fluorescent carbon nanoparticles and their transformation into functional nanoparticles are very challenging. Here we report red fluorescent carbon nanoparticle-based nanobioconjugates of <25 nm hydrodynamic size and their application as fluorescent cell labels. Hydrophobic carbon nanoparticles are synthesized via high temperature colloid-chemical approach and transformed into water-soluble functional nanoparticles via coating with amphiphilic polymer followed by covalent linking with desired biomolecules. Following this approach, carbon nanoparticles are functionalized with polyethylene glycol, primary amine, glucose, arginine, histidine, biotin and folic acid. These functional nanoparticles can be excited with blue/green light (i.e., 400-550 nm) to capture their emission spanning from 550 to 750 nm. Arginine and folic acid functionalized nanoparticles have been demonstrated as fluorescent cell labels where blue and green excitation has been used for imaging of labeled cells. The presented method can be extended for the development of carbon nanoparticle-based other bioimaging probes.

Synthesis and characterization of PEG-P(MAA-SS-VCL) nanoparticles

NASA Astrophysics Data System (ADS)

Yu, L. L.; Yang, K.; Mu, R. H.; Zhang, N.; Su, L.

2016-07-01

The PEG-P(MAA-SS-VCL) nanoparticles were obtained using disulfide containing dimethacrylate (SS) as cross-linking agent, using polyethylene glycol methyl acrylate (PEGMA), N-Vinyl-ε-caprolactam (VCL), and methacrylic acid (MAA) as monomers via homogeneous polymerization in aqueous. The PEG-P(MAA-SS-VCL) nanoparticles were characterized by FT-IR and TGA. The particle size and morphology variation in different environments were detected by dynamic light scattering (DLS) and scanning electron microscopy (SEM). It is the very method that PEG-P(MAA-SS-VCL) nanoparticles can be obtained in this study.

High spatial resolution mapping of surface plasmon resonance modes in single and aggregated gold nanoparticles assembled on DNA strands

NASA Astrophysics Data System (ADS)

Diaz-Egea, Carlos; Sigle, Wilfried; van Aken, Peter A.; Molina, Sergio I.

2013-07-01

We present the mapping of the full plasmonic mode spectrum for single and aggregated gold nanoparticles linked through DNA strands to a silicon nitride substrate. A comprehensive analysis of the electron energy loss spectroscopy images maps was performed on nanoparticles standing alone, dimers, and clusters of nanoparticles. The experimental results were confirmed by numerical calculations using the Mie theory and Gans-Mie theory for solving Maxwell's equations. Both bright and dark surface plasmon modes have been unveiled.

Red emissive cross-linked chitosan and their nanoparticles for imaging the nucleoli of living cells.

PubMed

Wang, Ke; Yuan, Xun; Guo, Zhenpeng; Xu, Jiying; Chen, Yi

2014-02-15

Biocompatible glutaraldehyde-cross-linked chitosan with new red fluorescence were prepared for the first time and were shaped into nanoparticles via inverse-microemulsion method. They could luminesce at ca. 670 nm either as powders and nanoparticles or in real and gelling solutions or suspensions, having a lifetime of 1.353 ns and a quantum yield of 0.08 in solution or 0.01 in solid state. The new-formed pyridinium structures and the intramolecular charge transfer effect are considered to be responsible for the new red emission, which have been proved by FTIR, (13)C NMR, and some calculation using Gaussian 09, respectively. Strikingly, they are quite inert and anti-photobleaching, with only <3% loss of fluorescent intensity per minute in average under a continuous laser illumination at 633 nm and 50 μW. Especially, their nanoparticles (5.6 nm) could enter into the negative nucleoli of living HeLa cells with low cytotoxicity for high contrast imaging inspections. Copyright © 2013 Elsevier Ltd. All rights reserved.

Emerging synthetic strategies for core cross-linked star (CCS) polymers and applications as interfacial stabilizers: bridging linear polymers and nanoparticles.

PubMed

Chen, Qijing; Cao, Xueteng; Xu, Yuanyuan; An, Zesheng

2013-10-01

Core cross-linked star (CCS) polymers become increasingly important in polymer science and are evaluated in many value-added applications. However, limitations exist to varied degrees for different synthetic methods. It is clear that improvement in synthetic efficiency is fundamental in driving this field moving even further. Here, the most recent advances are highlighted in synthetic strategies, including cross-linking with cross-linkers of low solubility, polymerization-induced self-assembly in aqueous-based heterogeneous media, and cross-linking via dynamic covalent bonds. The understanding of CCS polymers is also further refined to advocate their role as an intermediate between linear polymers and polymeric nanoparticles, and their use as interfacial stabilizers is rationalized within this context. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photocleavable Hydrogel-Coated Upconverting Nanoparticles: A Multifunctional Theranostic Platform for NIR Imaging and On-Demand Macromolecular Delivery.

PubMed

Jalani, Ghulam; Naccache, Rafik; Rosenzweig, Derek H; Haglund, Lisbet; Vetrone, Fiorenzo; Cerruti, Marta

2016-01-27

Lanthanide-doped upconverting nanoparticles (UCNPs) have emerged as excellent nanotransducers for converting longer wavelength near-infrared (NIR) light to shorter wavelengths spanning the ultraviolet (UV) to the visible (Vis) regions of the spectrum via a multiphoton absorption process, known as upconversion. Here, we report the development of NIR to UV-Vis-NIR UCNPs consisting of LiYF4:Yb(3+)/Tm(3+)@SiO2 individually coated with a 10 ± 2 nm layer of chitosan (CH) hydrogel cross-linked with a photocleavable cross-linker (PhL). We encapsulated fluorescent-bovine serum albumin (FITC-BSA) inside the gel. Under 980 nm excitation, the upconverted UV emission cleaves the PhL cross-links and instantaneously liberates the FITC-BSA under 2 cm thick tissue. The release is immediately arrested if the excitation source is switched off. The upconverted NIR light allows for the tracking of particles under the tissue. Nucleus pulposus (NP) cells cultured with UCNPs are viable both in the presence and in the absence of laser irradiation. Controlled drug delivery of large biomolecules and deep tissue imaging make this system an excellent theranostic platform for tissue engineering, biomapping, and cellular imaging applications.

Nanoniobia modification of CdS photoanode for an efficient and stable photoelectrochemical cell.

PubMed

Pareek, Alka; Paik, Pradip; Borse, Pramod H

2014-12-30

Herein we report the surface modification of a CdS film by niobia nanoparticles via thioglycerol as an organic linker and thus fabricate an efficient and a stable photoanode for a photoelectrochemical (PEC) cell. We have synthesized three differenly sized (∼3, ∼6 ,and ∼9 nm) niobia nanoparticles by a hydrothermal synthesis approach and have further investigated the particle-size-dependent PEC performance of the nanoparticle-modified CdS photoanode. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirm the formation of Nb2O5 nanoparticles that are prepared via decomposition of the niobium peroxo complex during the hydrothermal reaction and reveal the presence of surface OH(-) groups over niobia nanoparticles that impart a high catalytic property to a material. The nano-Nb2O5-modified photoanode displayed a 23-fold higher power conversion efficiency compared to that of CdS. This modified structure increases the open circuit voltage (OCV) from 0.65 to 0.77 V, which is attributed to the nano-Nb2O5-induced surface passivation effect over bare CdS. Linking of nanoparticles on the CdS surface improves the photocorrosion stability of the CdS photoanode for even longer than 4 h in contrast to the tens of minutes for the base CdS surface. The uniform coverage of the CdS photoanode surface by niobia nanoparticles is thus found to be the controlling parameter for achieving a higher PEC performance and stability of the photoanode. This finding directed us to design an improved CdS photoanode for efficient and prolonged PEC hydrogen generation from a PEC cell.

Controlled Fabrication of Gelatin Nanoparticles as Drug Carriers

NASA Astrophysics Data System (ADS)

Jahanshahi, M.; Sanati, M. H.; Minuchehr, Z.; Hajizadeh, S.; Babaei, Z.

2007-08-01

In recent years, significant effort has been devoted to develop nanotechnology for drug delivery since it offers a suitable means of delivering small molecular weight drugs, as well as macromolecules such as proteins, peptides or genes by either localized or targeted delivery to the tissue of interest. Nanotechnology focuses on formulating therapeutic agents in biocompatible nanocomposites such as nanoparticles, nanocapsules, micellar systems, and conjugates. Protein nanoparticles (BSA, HAS and gelatin) generally vary in size from 50-300 nm and they hold certain advantages such as greater stability during storage, stability in vivo, non-toxicity, non-antigen and ease to scale up during manufacture over the other drug delivery systems. The primary structure of gelatin offers many possibilities for chemical modification and covalent drug attachment. Here nanoparticles of gelatin type A were prepared by a two-step desolvation method as a colloidal drug delivery system and the essential parameters in fabrication were considered. Gelatin was dissolved in 25 mL distilled water under room temperature range. Then acetone was added to the gelatin solution as a desolvating agent to precipitate the high molecular weight (HMW) gelatin. The supernatant was discarded and the HMW gelatin re-dissolved by adding 25 mL distilled water and stirring at 600 rpm. Acetone were added drop-wise to form nanoparticles. At the end of the process, glutaraldehyde solution was used for preparing nanoparticles as a cross-linking agent, and stirred for 12h at 600 rpm. For purification stage we use centrifuge with 600rpm for 3 times. The objective of the present study is consideration of some factors such as temperature, gelatin concentration, agitation speed and the amount of acetone and their effects on size and distribution of nanoparticles. Among the all conditions, 60° C, 50 mg/ml gelatin concentration, 75 ml acetone had the best result and the nanoparticle size was under 170 nm. The effect of these factors for synthesis of gelatine nanoparticle is strongly discussed.

Bioactive Glass Nanoparticles: From Synthesis to Materials Design for Biomedical Applications

PubMed Central

Vichery, Charlotte; Nedelec, Jean-Marie

2016-01-01

Thanks to their high biocompatibility and bioactivity, bioactive glasses are very promising materials for soft and hard tissue repair and engineering. Because bioactivity and specific surface area intrinsically linked, the last decade has seen a focus on the development of highly porous and/or nano-sized materials. This review emphasizes the synthesis of bioactive glass nanoparticles and materials design strategies. The first part comprehensively covers mainly soft chemistry processes, which aim to obtain dispersible and monodispersed nanoparticles. The second part discusses the use of bioactive glass nanoparticles for medical applications, highlighting the design of materials. Mesoporous nanoparticles for drug delivery, injectable systems and scaffolds consisting of bioactive glass nanoparticles dispersed in a polymer, implant coatings and particle dispersions will be presented. PMID:28773412

DNA hydrogel as a template for synthesis of ultrasmall gold nanoparticles for catalytic applications.

PubMed

Zinchenko, Anatoly; Miwa, Yasuyuki; Lopatina, Larisa I; Sergeyev, Vladimir G; Murata, Shizuaki

2014-03-12

DNA cross-linked hydrogel was used as a matrix for synthesis of gold nanoparticles. DNA possesses a strong affinity to transition metals such as gold, which allows for the concentration of Au precursor inside a hydrogel. Further reduction of HAuCl4 inside DNA hydrogel yields well dispersed, non-aggregated spherical Au nanoparticles of 2-3 nm size. The average size of these Au nanoparticles synthesized in DNA hydrogel is the smallest reported so far for in-gel metal nanoparticles synthesis. DNA hybrid hydrogel containing gold nanoparticles showed high catalytic activity in the hydrogenation reaction of nitrophenol to aminophenol. The proposed soft hybrid material is promising as environmentally friendly and sustainable material for catalytic applications.

Insight into nanoparticle charging mechanism in nonpolar solvents to control the formation of Pt nanoparticle monolayers by electrophoretic deposition

DOE PAGES

Cernohorsky, Ondrej; Grym, Jan; Yatskiv, Roman; ...

2016-08-13

We report on the formation of Pt nanoparticle monolayers by electrophoretic deposition from nonpolar solvents. First, the growth kinetics of Pt nanoparticles prepared by the reverse micelle technique are described in detail. Second, a model of nanoparticle charging in nonpolar media is discussed and methods to control the nanoparticle charging are proposed. Lastly, essential parameters of the electrophoretic deposition process to control the deposition of nanoparticle monolayers are discussed and mechanisms of their formation are analyzed.

Insight into nanoparticle charging mechanism in nonpolar solvents to control the formation of Pt nanoparticle monolayers by electrophoretic deposition

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

Cernohorsky, Ondrej; Grym, Jan; Yatskiv, Roman

We report on the formation of Pt nanoparticle monolayers by electrophoretic deposition from nonpolar solvents. First, the growth kinetics of Pt nanoparticles prepared by the reverse micelle technique are described in detail. Second, a model of nanoparticle charging in nonpolar media is discussed and methods to control the nanoparticle charging are proposed. Lastly, essential parameters of the electrophoretic deposition process to control the deposition of nanoparticle monolayers are discussed and mechanisms of their formation are analyzed.

Hapten-derivatized nanoparticle targeting and imaging of gene expression by multimodality imaging systems.

PubMed

Cheng, C-M; Chu, P-Y; Chuang, K-H; Roffler, S R; Kao, C-H; Tseng, W-L; Shiea, J; Chang, W-D; Su, Y-C; Chen, B-M; Wang, Y-M; Cheng, T-L

2009-01-01

Non-invasive gene monitoring is important for most gene therapy applications to ensure selective gene transfer to specific cells or tissues. We developed a non-invasive imaging system to assess the location and persistence of gene expression by anchoring an anti-dansyl (DNS) single-chain antibody (DNS receptor) on the cell surface to trap DNS-derivatized imaging probes. DNS hapten was covalently attached to cross-linked iron oxide (CLIO) to form a 39+/-0.5 nm DNS-CLIO nanoparticle imaging probe. DNS-CLIO specifically bound to DNS receptors but not to a control single-chain antibody receptor. DNS-CLIO (100 microM Fe) was non-toxic to both B16/DNS (DNS receptor positive) and B16/phOx (control receptor positive) cells. Magnetic resonance (MR) imaging could detect as few as 10% B16/DNS cells in a mixture in vitro. Importantly, DNS-CLIO specifically bound to a B16/DNS tumor, which markedly reduced signal intensity. Similar results were also shown with DNS quantum dots, which specifically targeted CT26/DNS cells but not control CT26/phOx cells both in vitro and in vivo. These results demonstrate that DNS nanoparticles can systemically monitor the expression of DNS receptor in vivo by feasible imaging systems. This targeting strategy may provide a valuable tool to estimate the efficacy and specificity of different gene delivery systems and optimize gene therapy protocols in the clinic.

Preparation of Thermo-Responsive and Cross-Linked Fluorinated Nanoparticles via RAFT-Mediated Aqueous Polymerization in Nanoreactors.

PubMed

Ma, Jiachen; Zhang, Luqing; Geng, Bing; Azhar, Umair; Xu, Anhou; Zhang, Shuxiang

2017-01-25

In this work, a thermo-responsive and cross-linked fluoropolymer poly(2,2,2-Trifluoroethyl) methacrylate (PTFEMA) was successfully prepared by reversible addition-fragmentation chain transfer (RAFT) mediated aqueous polymerization with a thermo-responsive diblock poly(dimethylacrylamide- b - N -isopropylacrylamide) (PDMA- b -PNIPAM) that performed a dual function as both a nanoreactor and macro-RAFT agent. The cross-linked polymer particles proved to be in a spherical-like structure of about 50 nm in diameter and with a relatively narrow particle size distribution. ¹H-NMR and 19 F-NMR spectra showed that thermo-responsive diblock P(DMA- b -NIPAM) and cross-linked PTFEMA particles were successfully synthesized. Influence of the amount of ammonium persulfate (APS), the molar ratio of monomers to RAFT agent, influence of the amount of cross-linker on aqueous polymerization and thermo-responsive characterization of the particles are investigated. Monomer conversion increased from 44% to 94% with increasing the molar ratio of APS and P(DMA- b -NIPAM) from 1:9 to1:3. As the reaction proceeded, the particle size increased from 29 to 49 nm due to the consumption of TFEMA monomer. The size of cross-linked nanoparticles sharply decreased from 50.3 to 40.5 nm over the temperature range 14-44 °C, suggesting good temperature sensitivity for these nanoparticles.

Advanced Polymer Systems for Defence Applications: Power Generation, Protection and Sensing

DTIC Science & Technology

2014-05-01

oxide nanoparticles synthesized via non-sol-gel methods, e.g., via a flame process; and, (d) Amine sensors based on silver nanoparticle- doped ...Hongmin Chen, Guodong Chen, Xiaohong Gu, James L. Lee, E. E. Abdel-Hady, Y. C. Jean. Free Volumes, Glass Transitions, and Cross-Links in Zinc Oxide ...properties in a system of zinc oxide (ZnO) nanoparticles (20 nm) dispersed in waterborne polyurethane (WBPU) were measured using positron annihilation

Multivalent Nanoparticle Networks Enable Point of Care Detection of Human Phospholipase-A2 in Serum

PubMed Central

Burnapp, Mark; Bentham, Andrew; Hillier, David; Zabron, Abigail; Khan, Shahid; Tyreman, Matthew; Stevens, Molly M.

2017-01-01

A rapid and highly sensitive point of care (PoC) lateral flow assay for phospholipase-A2 (PLA2) is demonstrated in serum through the enzyme-triggered release of a new class of biotinylated multi-armed polymers from a liposome substrate. Signal from the enzyme activity is generated by the adhesion of polystreptavidin coated gold nanoparticle networks to the lateral flow device, which leads to the appearance of a red test line due to the localised surface plasmon resonance (LSPR) effect of the gold. The use of a liposome as the enzyme substrate and multivalent linkers to link the nanoparticles leads to amplification of the signal as the cleavage of a small amount of lipids is able to release a large amount of polymer linker and adhesion of an even larger amount of gold nanoparticles. By optimising the molecular weight and multivalency of these biotinylated polymer linkers the sensitivity of the device can be tuned to enable naked-eye detection of 1 nM human-PLA2 in serum within 10 minutes. This high sensitivity enabled the correct diagnosis of pancreatitis in diseased clinical samples against a set of healthy controls using PLA2 activity in a point of care device for the first time. PMID:25756526

A highly sensitive nanoscale pH-sensor using Au nanoparticles linked by a multifunctional Raman-active reporter molecule.

PubMed

Lawson, Latevi S; Chan, James W; Huser, Thomas

2014-07-21

Chemical sensing on the nanoscale has been breaking new ground since the discovery of surface enhanced Raman scattering (SERS). For nanoparticles, controlled particle aggregation is necessary to achieve the largest SERS enhancements. Therefore, aggregating agents such as salts or linker molecules are used in conjunction with chemically sensitive reporters in order to develop robust environmentally sensitive SERS probes. While salt-induced colloidal nanosphere aggregates have produced robust SERS signals, their variability in aggregate size contributes significantly to poor SERS signal reproducibility, which can complicate their use in in vitro cellular studies. Such systems often also lack reproducibility in spectral measurements between different nanoparticle clusters. Preaggregation of colloids via linkers followed by surface functionalization with reporter molecules results in the linker occupying valuable SERS hotspot volume which could otherwise be utilized by additional reporter molecules. Ideally, both functionalities should be obtained from a single molecule. Here, we report the use of 3,5-dimercaptobenzoic acid, a single multifunctional molecule that creates SERS hotspots via the controlled aggregation of nanoparticles, and also reports pH values. We show that 3,5-dimercaptobenzoic acid bound to Au nanospheres results in an excellent pH nanoprobe, producing very robust, and highly reproducible SERS signals that can report pH across the entire physiological range with excellent pH resolution. To demonstrate the efficacy of our novel pH reporters, these probes were also used to image both the particle and pH distribution in the cytoplasm of human induced pluripotent stem cells (hiPSCs).

Size-controlled synthesis of transition metal nanoparticles through chemical and photo-chemical routes

NASA Astrophysics Data System (ADS)

Tangeysh, Behzad

The central objective of this work is developing convenient general procedures for controlling the formation and stabilization of nanoscale transition metal particles. Contemporary interest in developing alternative synthetic approaches for producing nanoparticles arises in large part from expanding applications of the nanomaterials in areas such as catalysis, electronics and medicine. This research focuses on advancing the existing nanoparticle synthetic routes by using a new class of polymer colloid materials as a chemical approach, and the laser irradiation of metal salt solution as a photo-chemical method to attain size and shape selectivity. Controlled synthesis of small metal nanoparticles with sizes ranging from 1 to 5nm is still a continuing challenge in nanomaterial synthesis. This research utilizes a new class of polymer colloid materials as nano-reactors and protective agents for controlling the formation of small transition metal nanoparticles. The polymer colloid particles were formed from cross-linking of dinegatively charged metal precursors with partially protonated poly dimethylaminoethylmethacrylate (PDMAEMA). Incorporation of [PtCl6]2- species into the colloidal particles prior to the chemical reduction was effectively employed as a new strategy for synthesis of unusually small platinum nanoparticles with narrow size distributions (1.12 +/-0.25nm). To explore the generality of this approach, in a series of proof-of-concept studies, this method was successfully employed for the synthesis of small palladium (1.4 +/-0.2nm) and copper nanoparticles (1.5 +/-0.6nm). The polymer colloid materials developed in this research are pH responsive, and are designed to self-assemble and/or disassemble by varying the levels of protonation of the polymer chains. This unique feature was used to tune the size of palladium nanoparticles in a small range from 1nm to 5nm. The procedure presented in this work is a new convenient room temperature route for synthesis of small nanoparticles, and its application can be extended to the formation of other transition metals and alloy nanoparticles. This research also focuses on developing new photo-chemical routes for controlling the size and shape of the nanoparticles through high-intensity ultra-fast laser irradiation of metal salt solution. One of the core objectives of this work is to explore the special capabilities of shaped laser pulses in formation of metal nanoparticles through irradiation of the solutions by using simultaneous spatial and temporal focusing (SSTF). Femtosecond laser irradiation has not yet been widely applied for nanoparticle synthesis, and offers new regimes of energy deposition for synthesis of nanomaterials. Photo-reduction of aqueous [AuCl4]- solution to the gold nanoparticles (AuNPs) has been applied as a model process for optimizing the experimental procedures, and evaluating the potential of shaped laser pulses in the synthesis of AuNPs. Systematic manipulation of the laser parameters and experimental conditions provided effective strategies to control the size of Au nanoparticles in strong laser fields. Varying the concentration of polyethylene glycol (PEG45) as a surfactant effectively tuned the size of AuNPs from 3.9 +/-0.7nm to 11.0 +/-2.4nm, and significantly increased the rate of Au(III) reduction during irradiation. Comparative studies revealed the capability of shaped laser pulses in the generation of smaller and more uniform AuNPs (5.8 +/-1.1nm) relative to the other conventional laser irradiation methods (7.2 +/-2.9nm). Furthermore, a new laser-assisted approach has been developed for selective formation of triangular Au nanoplates in the absence of any surfactant molecule. This method relies on rapid energy deposition by using shaped, ultra-intense laser pulses to generate Au seeds in aqueous [AuCl4]- solution, and the slow post-irradiation reduction of un-reacted [AuCl4]- species by using H2O2 as a mild reducing agent. Variation of the laser irradiation-time was found as an effective strategy to tune the morphology of Au nanomaterials from nanospheres to triangular nanoplates. The surfactant-free Au nanoplates produced in this research can be readily functionalized with a variety of target molecules or surfactants for desirable applications such as biomedicine. The concept of rapid laser processing followed by in situ chemical reduction can be expanded as a general methodology for high-yield production of nanomaterials, and provides a series of new laser dependent parameters for controlling the nanoparticle formation.

Control of interface between anatase TiO2 nanoparticles and rutile TiO2 nanorods for efficient photocatalytic H2 generation

NASA Astrophysics Data System (ADS)

Xia, Xiaohong; Peng, Shuai; Bao, Yuwen; Wang, Yu; Lei, Binglong; Wang, Zhuo; Huang, Zhongbing; Gao, Yun

2018-02-01

In recent years, production of H2 through photocatalytic water splitting has attracted considerable attention in the chemistry and material fields. In this work, TiO2 based heterojunction photocatalyst, which is consisted of rutile nanorods and anatase nanoparticles, is systematically studied by controlling the HCl concentration in hydrothermal process. With the help of loaded Pt, an interesting two-peak feature ("M" shape) is observed in the HCl-dependent H2 production efficiency. The peak values are 54.3 mmol h-1 g-1 and 74.4 mmol h-1 g-1, corresponding to 83.9% and 12% anatase phase, respectively. A detailed analysis based on the microstructure and photoluminescence (PL) spectra indicate that the "M" shape feature is directly linked to the HCl-controlled interface area. Moreover, an unexpected zero interface area is revealed at an intermediate HCl concentration. In terms of homogeneous and heterogeneous nucleations, an interface growth mechanism is proposed to clarify its HCl-sensitive character. This work provides a route to enhance the photocatalytic activity in TiO2 based photocatalyst via increasing the interface area.

Green synthesis and characterization of alginate nanoparticles and its role as a biosorbent for Cr(VI) ions

NASA Astrophysics Data System (ADS)

Geetha, P.; Latha, M. S.; Pillai, Saumya S.; Deepa, B.; Santhosh Kumar, K.; Koshy, Mathew

2016-02-01

Green synthesis of nanoparticles has attained considerable attention in recent years because of its myriad of applications including drug delivery, tissue engineering and water purification. In the present study, alginate nanoparticles stabilized by honey were prepared by cross-linking aqueous solution of alginate with calcium ions. Honey mediated synthesis has been reported earlier for the production of metal nanoparticles. However no literature is available on the use of this technique for polymeric nanoparticles. Highly stable nanoparticles of 10-100 nm size were generated by this technique. The synthesised nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopic techniques. Potential of using these nanoparticles for heavy metal removal was studied by using Cr(VI) from aqueous solution, where a maximum removal efficiency of 93.5% was obtained. This method was also successfully employed for the production of other polymeric nanoparticles like casein, chitosan and albumin.

Direct recognition of superparamagnetic nanocrystals by macrophage scavenger receptor SR-AI.

PubMed

Chao, Ying; Karmali, Priya P; Mukthavaram, Rajesh; Kesari, Santosh; Kouznetsova, Valentina L; Tsigelny, Igor F; Simberg, Dmitri

2013-05-28

Scavenger receptors (SRs) are molecular pattern recognition receptors that have been shown to mediate opsonin-independent uptake of therapeutic and imaging nanoparticles, underlying the importance of SRs in nanomedicine. Unlike pathogens, engineered nanomaterials offer great flexibility in control of surface properties, allowing addressing specific questions regarding the molecular mechanisms of nanoparticle recognition. Recently, we showed that SR-type AI/II mediates opsonin-independent internalization of dextran superparamagnetic iron oxide (SPIO) nanoparticles via positively charged extracellular collagen-like domain. To understand the mechanism of opsonin-independent SPIO recognition, we tested the binding and uptake of nanoparticles with different surface coatings by SR-AI. SPIO coated with 10 kDa dextran was efficiently recognized and taken up by SR-AI transfected cells and J774 macrophages, while SPIO with 20 kDa dextran coating or cross-linked dextran hydrogel avoided the binding and uptake. Nanoparticle negative charge density and zeta-potential did not correlate with SR-AI binding/uptake efficiency. Additional experiments and computer modeling revealed that recognition of the iron oxide crystalline core by the positively charged collagen-like domain of SR-AI is sterically hindered by surface polymer coating. Importantly, the modeling revealed a strong complementarity between the surface Fe-OH groups of the magnetite crystal and the charged lysines of the collagen-like domain of SR-AI, suggesting a specific recognition of SPIO crystalline surface. These data provide an insight into the molecular recognition of nanocrystals by innate immunity receptors and the mechanisms whereby polymer coatings promote immune evasion.

Colloidal Covalent Organic Frameworks

PubMed Central

2017-01-01

Covalent organic frameworks (COFs) are two- or three-dimensional (2D or 3D) polymer networks with designed topology and chemical functionality, permanent porosity, and high surface areas. These features are potentially useful for a broad range of applications, including catalysis, optoelectronics, and energy storage devices. But current COF syntheses offer poor control over the material’s morphology and final form, generally providing insoluble and unprocessable microcrystalline powder aggregates. COF polymerizations are often performed under conditions in which the monomers are only partially soluble in the reaction solvent, and this heterogeneity has hindered understanding of their polymerization or crystallization processes. Here we report homogeneous polymerization conditions for boronate ester-linked, 2D COFs that inhibit crystallite precipitation, resulting in stable colloidal suspensions of 2D COF nanoparticles. The hexagonal, layered structures of the colloids are confirmed by small-angle and wide-angle X-ray scattering, and kinetic characterization provides insight into the growth process. The colloid size is modulated by solvent conditions, and the technique is demonstrated for four 2D boronate ester-linked COFs. The diameter of individual COF nanoparticles in solution is monitored and quantified during COF growth and stabilization at elevated temperature using in situ variable-temperature liquid cell transmission electron microscopy imaging, a new characterization technique that complements conventional bulk scattering techniques. Solution casting of the colloids yields a free-standing transparent COF film with retained crystallinity and porosity, as well as preferential crystallite orientation. Collectively this structural control provides new opportunities for understanding COF formation and designing morphologies for device applications. PMID:28149954

Characterization of Magnetic NiFe Nanoparticles with Controlled Bimetallic Composition

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

Liu, Yan; Chi, Yanxiu; Shan, Shiyao

2014-02-25

The exploration of the magnetic properties of bimetallic alloy nanoparticles for various technological applications requires the ability to control the morphology, composition, and surface properties. In this report, we describe new findings of an investigation of the morphology and composition of NiFe alloy nanoparticles synthesized under controlled conditions. The controllability over the bimetallic composition has been demonstrated by the observation of an approximate linear relationship between the composition in the nanoparticles and in the synthetic feeding. The morphology of the NiFe nanoparticles is consistent with an fcc-type alloy, with the lattice strain increasing linearly with the iron content in themore » nanoparticles. The alloy nanoparticles exhibit remarkable resistance to air oxidation in comparison with Ni or Fe particles. The thermal stability and the magnetic properties of the as-synthesized alloy nanoparticles are shown to depend on the composition. The alloy nanoparticles have also be sown to display low saturation magnetization and coercivity values in comparison with the Ni nanoparticles, in line with the superparamagnetic characteristic. These findings have important implications for the design of stable and controllable magnetic nanoparticles for various technological applications.« less

Replacement of Antibodies in Pseudo-ELISAs: Molecularly Imprinted Nanoparticles for Vancomycin Detection.

PubMed

Canfarotta, Francesco; Smolinska-Kempisty, Katarzyna; Piletsky, Sergey

2017-01-01

The enzyme-linked immunosorbent assay (ELISA) is a widely employed analytical test used to quantify a given molecule. It relies on the use of specific antibodies, linked to an enzyme, to target the desired molecule. The reaction between the enzyme and its substrate gives rise to the analytical signal that can be quantified. Thanks to their robustness and low cost, molecularly imprinted polymer nanoparticles (nanoMIPs) are a viable alternative to antibodies. Herein, we describe the synthesis of nanoMIPs imprinted for vancomycin and their subsequent application in an ELISA-like format for direct replacement of antibodies.

Hybrid nanoporous silicon optical biosensor architectures for biological sample analysis

NASA Astrophysics Data System (ADS)

Bonanno, Lisa M.; Zheng, Hong; DeLouise, Lisa A.

2010-02-01

This work focuses on demonstrating proof-of-concept for a novel nanoparticle optical signal amplification scheme employing hybrid porous silicon (PSi) sensors. We are investigating the development of target responsive hydrogels integrated with PSi optical transducers. These hybrid-PSi sensors can be designed to provide a tunable material response to target concentration ranging from swelling to complete chain dissolution. The corresponding refractive index changes are significant and readily detected by the PSi transducer. However, to increase signal to noise, lower the limit of detection, and provide a visual read out capability, we are investigating the incorporation of high refractive index nanoparticles (NP) into the hydrogel for optical signal amplification. These NPs can be nonspecifically encapsulated, or functionalized with bioactive ligands to bind polymer chains or participate in cross linking. In this work, we demonstrate encapsulation of high refractive index QD nanoparticles into a 5wt% polyacrylamide hydrogel crosslinked with N,N'-methylenebisacrylamide (BIS) and N,N Bis-acryloyl cystamine (BAC). A QD loading (~0.29 wt%) produced a 2X larger optical shift compared to the control. Dissolution of disulphide crosslinks, using Tris[2-carboxyethyl] phosphine (TCEP) reducing agent, induced gel swelling and efficient QD release. We believe this hybrid sensor concept constitutes a versatile technology platform capable of detecting a wide range of bio/chemical targets provided target analogs can be linked to the polymer backbone and crosslinks can be achieved with target responsive multivalent receptors, such a antibodies. The optical signal amplification scheme will enable a lower limit of detection sensitivity not yet demonstrated with PSi technology and colorimetric readout visible to the naked eye.

3D visualization of additive occlusion and tunable full-spectrum fluorescence in calcite

PubMed Central

Green, David C.; Ihli, Johannes; Thornton, Paul D.; Holden, Mark A.; Marzec, Bartosz; Kim, Yi-Yeoun; Kulak, Alex N.; Levenstein, Mark A.; Tang, Chiu; Lynch, Christophe; Webb, Stephen E. D.; Tynan, Christopher J.; Meldrum, Fiona C.

2016-01-01

From biomineralization to synthesis, organic additives provide an effective means of controlling crystallization processes. There is growing evidence that these additives are often occluded within the crystal lattice. This promises an elegant means of creating nanocomposites and tuning physical properties. Here we use the incorporation of sulfonated fluorescent dyes to gain new understanding of additive occlusion in calcite (CaCO3), and to link morphological changes to occlusion mechanisms. We demonstrate that these additives are incorporated within specific zones, as defined by the growth conditions, and show how occlusion can govern changes in crystal shape. Fluorescence spectroscopy and lifetime imaging microscopy also show that the dyes experience unique local environments within different zones. Our strategy is then extended to simultaneously incorporate mixtures of dyes, whose fluorescence cascade creates calcite nanoparticles that fluoresce white. This offers a simple strategy for generating biocompatible and stable fluorescent nanoparticles whose output can be tuned as required. PMID:27857076

Photosensitizer conjugated iron oxide nanoparticles for simultaneous in vitro magneto-fluorescent imaging guided photodynamic therapy.

PubMed

Nafiujjaman, Md; Revuri, Vishnu; Nurunnabi, Md; Cho, Kwang Jae; Lee, Yong-Kyu

2015-04-04

In this study, photosensitizer conjugated iron oxide nanoparticles were strategically designed and prepared for simultaneous PDT and dual-mode fluorescence/MR imaging. The MRI contrast agent Fe3O4 was modified by APTES to functionalize the surface and further to link with heparin-pheophorbide-A conjugates.

Different preparation methods and characterization of magnetic maghemite coated with chitosan

NASA Astrophysics Data System (ADS)

Hojnik Podrepšek, Gordana; Knez, Željko; Leitgeb, Maja

2013-06-01

The preparation of maghemite (γ-Fe2O3) micro- and nanoparticles coated with chitosan, used as carriers for immobilized enzymes, was investigated. γ-Fe2O3 nanoparticles were synthesized by coprecipitation of Fe2+ and Fe3+ ions in the presence of ammonium. They were coated with chitosan by the microemulsion process, suspension cross-linking technique, and covalent binding of chitosan on the γ-Fe2O3 surface. The methods distinguished the concentration of chitosan, concentration of acetic acid solution, concentration of a cross-linking agent, temperature of synthesis, pH of the medium, and time of synthesis. γ-Fe2O3 micro- and nanoparticles coated with chitosan prepared after three preparation methods were evaluated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy analysis, energy dispersive spectrometry, thermogravimetric analysis, differential scanning calorimetry analysis, vibrating sample magnetometry, dynamic light scattering, laser diffraction granulometry, and X-ray diffractometry. These positive attributes demonstrated that these magnetic micro- and nanoparticles coated with chitosan may be used as a promising carrier for further diverse biomedical applications.

Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells

NASA Astrophysics Data System (ADS)

Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

2011-03-01

We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing. Electronic supplementary information (ESI) available: Additional TEM data, supplemental light scattering measurements, absorbance and fluorescence emission spectra, and photostability measurements. See DOI: 10.1039/c0nr00746c

Synthesis, characterization and in vitro studies of doxorubicin-loaded magnetic nanoparticles grafted to smart copolymers on A549 lung cancer cell line.

PubMed

Akbarzadeh, Abolfazl; Samiei, Mohammad; Joo, Sang Woo; Anzaby, Maryam; Hanifehpour, Younes; Nasrabadi, Hamid Tayefi; Davaran, Soodabeh

2012-12-18

The aim of present study was to develop the novel methods for chemical and physical modification of superparamagnetic iron oxide nanoparticles (SPIONs) with polymers via covalent bonding entrapment. These modified SPIONs were used for encapsulation of anticancer drug doxorubicin. At first approach silane-grafted magnetic nanoparticles was prepared and used as a template for polymerization of the N-isopropylacrylamide (NIPAAm) and methacrylic acid (MAA) via radical polymerization. This temperature/pH-sensitive copolymer was used for preparation of DOX-loaded magnetic nanocomposites. At second approach Vinyltriethoxysilane-grafted magnetic nanoparticles were used as a template to polymerize PNIPAAm-MAA in 1, 4 dioxan and methylene-bis-acrylamide (BIS) was used as a cross-linking agent. Chemical composition and magnetic properties of Dox-loaded magnetic hydrogel nanocomposites were analyzed by FT-IR, XRD, and VSM. The results demonstrate the feasibility of drug encapsulation of the magnetic nanoparticles with NIPAAm-MAA copolymer via covalent bonding. The key factors for the successful prepardtion of magnetic nanocomposites were the structure of copolymer (linear or cross-linked), concentration of copolymer and concentration of drug. The influence of pH and temperature on the release profile of doxorubicin was examined. The in vitro cytotoxicity test (MTT assay) of both magnetic DOx-loaded nanoparticles was examined. The in vitro tests showed that these systems are no toxicity and are biocompatible. IC50 of DOx-loaded Fe3O4 nanoparticles on A549 lung cancer cell line showed that systems could be useful in treatment of lung cancer.

Mass production and size control of lipid-polymer hybrid nanoparticles through controlled microvortices

PubMed Central

Kim, YongTae; Chung, Bomy Lee; Ma, Mingming; Mulder, Willem J. M.; Fayad, Zahi A.; Farokhzad, Omid C.; Langer, Robert

2012-01-01

Lipid-polymer hybrid (LPH) nanoparticles can deliver a wide range of therapeutic compounds in a controlled manner. LPH nanoparticle syntheses using microfluidics improve the mixing process, but are restricted by a low throughput. In this study we present a pattern-tunable microvortex platform that allows mass production and size control of LPH nanoparticles with superior reproducibility and homogeneity. We demonstrate that by varying flow rates (i.e. Reynolds number (30∼150)) we can control the nanoparticle size (30∼170nm) with high productivity (∼3g/hour) and low polydispersity (∼0.1). Our approach may contribute to efficient development and optimization of a wide range of multicomponent nanoparticles for medical imaging and drug delivery. PMID:22716029

Interaction of inorganic nanoparticles with graphene.

PubMed

Das, Barun; Choudhury, Biswajit; Gomathi, A; Manna, Arun K; Pati, S K; Rao, C N R

2011-04-04

The changes in the electronic and magnetic properties of graphene induced by interaction with semiconducting oxide nanoparticles such as ZnO and TiO(2) and with magnetic nanoparticles such as Fe(3)O(4), CoFe(2)O(4), and Ni are investigated by using Raman spectroscopy, magnetic measurements, and first-principles calculations. Significant electronic and magnetic interactions between the nanoparticles and graphene are found. The findings suggest that changes in magnetization as well as the Raman shifts are directly linked to charge transfer between the deposited nanoparticles and graphene. The study thus demonstrates significant effects in tailoring the electronic structure of graphene for applications in futuristic electronic devices. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Size-Tunable and Functional Core-Shell Structured Silica Nanoparticles for Drug Release

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

Chi, Fangli; Guo, Ya Nan; Liu, Jun

2010-02-18

Size-tunable silica cross-linked micellar core-shell nanoparticles (SCMCSNs) were successfully synthesized from a Pluronic nonionic surfactant (F127) template system with organic swelling agents such as 1,3,5-trimethylbenzene (TMB) and octanoic acid at room temperature. The size and morphology of SCMCSNs were directly evidenced by TEM imaging and DLS measurements (up to ~90 nm). Pyrene and coumarin 153 (C153) were used as fluorescent probe molecules to investigate the effect and location of swelling agent molecules. Papaverine as a model drug was used to measure the loading capacity and release property of nanoparticles. The swelling agents can enlarge the nanoparticle size and improve themore » drug loading capacity of nanoparticles. Moreover, the carboxylic acid group of fatty acid can adjust the release behavior of the nanoparticles.« less

New insights into the adsorption of 3-(trimethoxysilyl)propylmethacrylate on hydroxylated ZnO nanopowders.

PubMed

Bressy, Christine; Ngo, Van Giang; Ziarelli, Fabio; Margaillan, André

2012-02-14

Functionalization of zinc oxide (ZnO) nano-objects by silane grafting is an attractive method to provide nanostructured materials with a variety of surface properties. Active hydroxyl groups on the oxide surface are one of the causes governing the interfacial bond strength in nanohybrid particles. Here, "as-prepared" and commercially available zinc oxide nanopowders with a wide range of surface hydroxyl density were functionalized by a well-known polymerizable silane coupling agent, i.e., 3-(trimethoxysilyl)propylmethacrylate (MPS). Fourier transform infrared (FTIR) and solid-state (13)C and (29)Si nuclear magnetic resonance (NMR) spectroscopic investigations demonstrated that the silane coupling agent was fully hydrolyzed and linked to the hydroxyl groups already present on the particle surface through covalent and hydrogen bonds. Due to a basic catalyzed condensation of MPS with water, a siloxane layer was shown to be anchored to the nanoparticles through mono- and tridentate structures. Quantitative investigations were performed by thermogravimetric (TGA) and elemental analyses. The amount of silane linked to ZnO particles was shown to be affected by the amount of isolated hydroxyl groups available to react on the particle surface. For as-prepared ZnO nanoparticles, the number of isolated and available hydroxyl groups per square nanometer was up to 3 times higher than the one found on commercially available ZnO nanoparticles, leading to higher amounts of polymerizable silane agent linked to the surface. The MPS molecules were shown to be mainly oriented perpendicular to the oxide surface for all the as-prepared ZnO nanoparticles, whereas a parallel orientation was found for the preheated commercially ZnO nanopowders. In addition, ZnO nanoparticles were shown to be hydrophobized by the MPS treatment with water contact angles higher than 60°.

Catalysts synthesized by selective deposition of Fe onto Pt for the water-gas shift reaction

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

Aragao, Isaias Barbosa; Ro, Insoo; Liu, Yifei

FePt bimetallic catalysts with intimate contact between the two metals were synthesized by controlled surface reactions (CSR) of (cyclohexadiene)iron tricarbonyl with hydrogen-treated supported Pt nanoparticles. Adsorption of the iron precursor on a Pt/SiO2 catalyst was studied, showing that the Fe loading could be increased by performing multiple CSR cycles, and the efficiency of this process was linked to the renewal of adsorption sites by a reducing pretreatment. The catalytic activity of these bimetallic catalysts for the water gas shift reaction was improved due to promotion by iron, likely linked to H2O activation on FeOx species at or near the Ptmore » surface, mostly in the (II) oxidation state.« less

Catalysts synthesized by selective deposition of Fe onto Pt for the water-gas shift reaction

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

Aragao, Isaias Barbosa; Ro, Insoo; Liu, Yifei

FePt bimetallic catalysts with intimate contact between the two metals were synthesized by controlled surface reactions (CSR) of (cyclohexadiene)iron tricarbonyl with hydrogen-treated supported Pt nanoparticles. Adsorption of the iron precursor on a Pt/SiO 2 catalyst was studied, showing that the Fe loading could be increased by performing multiple CSR cycles, and the efficiency of this process was linked to the renewal of adsorption sites by a reducing pretreatment. Here, the catalytic activity of these bimetallic catalysts for the water gas shift reaction was improved due to promotion by iron, likely linked to H 2O activation on FeO x species atmore » or near the Pt surface, mostly in the (II) oxidation state.« less

Catalysts synthesized by selective deposition of Fe onto Pt for the water-gas shift reaction

DOE PAGES

Aragao, Isaias Barbosa; Ro, Insoo; Liu, Yifei; ...

2017-10-04

FePt bimetallic catalysts with intimate contact between the two metals were synthesized by controlled surface reactions (CSR) of (cyclohexadiene)iron tricarbonyl with hydrogen-treated supported Pt nanoparticles. Adsorption of the iron precursor on a Pt/SiO 2 catalyst was studied, showing that the Fe loading could be increased by performing multiple CSR cycles, and the efficiency of this process was linked to the renewal of adsorption sites by a reducing pretreatment. Here, the catalytic activity of these bimetallic catalysts for the water gas shift reaction was improved due to promotion by iron, likely linked to H 2O activation on FeO x species atmore » or near the Pt surface, mostly in the (II) oxidation state.« less

Protein Viability on Au Nanoparticles during an Electrospray and Electrostatic-Force-Directed Assembly Process

DOE PAGES

Mao, Shun; Lu, Ganhua; Yu, Kehan; ...

2010-01-01

We study the protein viability on Au nanoparticles during an electrospray and electrostatic-force-directed assembly process, through which Au nanoparticle-antibody conjugates are assembled onto the surface of carbon nanotubes (CNTs) to fabricate carbon nanotube field-effect transistor (CNTFET) biosensors. Enzyme-linked immunosorbent assay (ELISA) and field-effect transistor (FET) measurements have been used to investigate the antibody activity after the nanoparticle assembly. Upon the introduction of matching antigens, the colored reaction from the ELISA and the change in the electrical characteristic of the CNTFET device confirm that the antibody activity is preserved during the assembly process.

Gold nanorod linking to control plasmonic properties in solution and polymer nanocomposites.

PubMed

Ferrier, Robert C; Lee, Hyun-Su; Hore, Michael J A; Caporizzo, Matthew; Eckmann, David M; Composto, Russell J

2014-02-25

A novel, solution-based method is presented to prepare bifunctional gold nanorods (B-NRs), assemble B-NRs end-to-end in various solvents, and disperse linked B-NRs in a polymer matrix. The B-NRs have poly(ethylene glycol) grafted along its long axis and cysteine adsorbed to its ends. By controlling cysteine coverage, bifunctional ligands or polymer can be end-grafted to the AuNRs. Here, two dithiol ligands (C6DT and C9DT) are used to link the B-NRs in organic solvents. With increasing incubation time, the nanorod chain length increases linearly as the longitudinal surface plasmon resonance shifts toward lower adsorption wavelengths (i.e., red shift). Analogous to step-growth polymerization, the polydispersity in chain length also increases. Upon adding poly(ethylene glycol) or poly(methyl methacrylate) to chloroform solution with linked B-NR, the nanorod chains are shown to retain end-to-end linking upon spin-casting into PEO or PMMA films. Using quartz crystal microbalance with dissipation (QCM-D), the mechanism of nanorod linking is investigated on planar gold surfaces. At submonolayer coverage of cysteine, C6DT molecules can insert between cysteines and reach an areal density of 3.4 molecules per nm(2). To mimic the linking of Au NRs, this planar surface is exposed to cysteine-coated Au nanoparticles, which graft at 7 NPs per μm(2). This solution-based method to prepare, assemble, and disperse Au nanorods is applicable to other nanorod systems (e.g., CdSe) and presents a new strategy to assemble anisotropic particles in organic solvents and polymer coatings.

Gold Nanorod Linking to Control Plasmonic Properties in Solution and Polymer Nanocomposites

PubMed Central

2015-01-01

A novel, solution-based method is presented to prepare bifunctional gold nanorods (B-NRs), assemble B-NRs end-to-end in various solvents, and disperse linked B-NRs in a polymer matrix. The B-NRs have poly(ethylene glycol) grafted along its long axis and cysteine adsorbed to its ends. By controlling cysteine coverage, bifunctional ligands or polymer can be end-grafted to the AuNRs. Here, two dithiol ligands (C6DT and C9DT) are used to link the B-NRs in organic solvents. With increasing incubation time, the nanorod chain length increases linearly as the longitudinal surface plasmon resonance shifts toward lower adsorption wavelengths (i.e., red shift). Analogous to step-growth polymerization, the polydispersity in chain length also increases. Upon adding poly(ethylene glycol) or poly(methyl methacrylate) to chloroform solution with linked B-NR, the nanorod chains are shown to retain end-to-end linking upon spin-casting into PEO or PMMA films. Using quartz crystal microbalance with dissipation (QCM-D), the mechanism of nanorod linking is investigated on planar gold surfaces. At submonolayer coverage of cysteine, C6DT molecules can insert between cysteines and reach an areal density of 3.4 molecules per nm2. To mimic the linking of Au NRs, this planar surface is exposed to cysteine-coated Au nanoparticles, which graft at 7 NPs per μm2. This solution-based method to prepare, assemble, and disperse Au nanorods is applicable to other nanorod systems (e.g., CdSe) and presents a new strategy to assemble anisotropic particles in organic solvents and polymer coatings. PMID:24483622

Tuning acoustic and mechanical properties of materials for ultrasound phantoms and smart substrates for cell cultures.

PubMed

Cafarelli, A; Verbeni, A; Poliziani, A; Dario, P; Menciassi, A; Ricotti, L

2017-02-01

Materials with tailored acoustic properties are of great interest for both the development of tissue-mimicking phantoms for ultrasound tests and smart scaffolds for ultrasound mediated tissue engineering and regenerative medicine. In this study, we assessed the acoustic properties (speed of sound, acoustic impedance and attenuation coefficient) of three different materials (agarose, polyacrylamide and polydimethylsiloxane) at different concentrations or cross-linking levels and doped with different concentrations of barium titanate ceramic nanoparticles. The selected materials, besides different mechanical features (stiffness from few kPa to 1.6MPa), showed a wide range of acoustic properties (speed of sound from 1022 to 1555m/s, acoustic impedance from 1.02 to 1.67MRayl and attenuation coefficient from 0.2 to 36.5dB/cm), corresponding to ranges in which natural soft tissues can fall. We demonstrated that this knowledge can be used to build tissue-mimicking phantoms for ultrasound-based medical procedures and that the mentioned measurements enable to stimulate cells with a highly controlled ultrasound dose, taking into account the attenuation due to the cell-supporting scaffold. Finally, we were able to correlate for the first time the bioeffect on human fibroblasts, triggered by piezoelectric barium titanate nanoparticles activated by low-intensity pulsed ultrasound, with a precise ultrasound dose delivered. These results may open new avenues for the development of both tissue-mimicking materials for ultrasound phantoms and smart triggerable scaffolds for tissue engineering and regenerative medicine. This study reports for the first time the results of a systematic acoustic characterization of agarose, polyacrylamide and polydimethylsiloxane at different concentrations and cross-linking extents and doped with different concentrations of barium titanate nanoparticles. These results can be used to build tissue-mimicking phantoms, useful for many ultrasound-based medical procedures, and to fabricate smart materials for stimulating cells with a highly controlled ultrasound dose. Thanks to this knowledge, we correlated for the first time a bioeffect (the proliferation increase) on human fibroblasts, triggered by piezoelectric nanoparticles, with a precise US dose delivered. These results may open new avenues for the development of both tissue-mimicking phantoms and smart triggerable scaffolds for tissue engineering and regenerative medicine. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Using Antifreeze Proteins to understand ice microstructure evolution

NASA Astrophysics Data System (ADS)

Bayer-Giraldi, Maddalena; Azuma, Nobuhiko; Takata, Morimasa; Weikusat, Christian; Kondo, Hidemasa; Kipfstuhl, Sepp

2017-04-01

Polar ice sheets are considered a unique climate archive. The chemical analysis of its impurities and the development of its microstructure with depth give insight in past climate conditions as well as in the development of the ice sheet with time and deformation. Microstructural patterns like small grain size observed in specific depths are thought to be linked to the retarding effect of impurities on ice grain growth. Clear evidence of size or chemical composition of the impurities causing this effect is missing, but in this context a major role of nanoparticles has been suggested. In order to shed light on different mechanisms by which nanoparticles can control microstructure development we used antifreeze proteins (AFPs) as proxies for particles in ice. These proteins are small nanoparticles, approx. 5 nm in size, with the special characteristics of firmly binding to ice through several hydrogen bonds. We used AFPs from the sea-ice microalgae Fragilariopsis cylindrus (fcAFPs) in bubble-free, small-grained polycrystalline ice obtained by the phase-transition size refinement method. We explain how fcAFP bind to ice by presenting the 3-D-protein structure model inferred by X-ray structure analysis, and show the importance of the chemical interaction between particles and ice in controlling normal grain growth, comparing fcAFPs to other protein nanoparticles. We used modifications of fcAFPs for particle localization through fluorescence spectroscopy. Furthermore, the effect of fcAFPs on the driving factors for ice deformation during creep, i.e. on internal dislocations due to incorporation within the lattice and on the mobility of grain boundaries due to pinning, makes these proteins particularly interesting in studying the process of ice deformation.

Controlled release of lovastatin from poly(lactic-co-glycolic acid) nanoparticles for direct pulp capping in rat teeth.

PubMed

Lin, Hung-Pin; Tu, Han-Ping; Hsieh, Yu-Ping; Lee, Bor-Shiunn

2017-01-01

Statin at appropriate concentrations has been shown to induce odontoblastic differentiation, dentinogenesis, and angiogenesis. However, using a carrier to control statin release might reduce toxicity and enhance its therapeutic effects. The aim of this study was to prepare poly(d,l-lactide- co -glycolide acid) (PLGA) nanoparticles that contain lovastatin for application in direct pulp capping. The PLGA-lovastatin particle size was determined using dynamic light scattering measurements and transmission electron microscopy. In addition, the release of lovastatin was quantified using a UV-Vis spectrophotometer. The cytotoxicity and alkaline phosphatase (ALP) activity of PLGA-lovastatin nanoparticles on human dental pulp cells were investigated. Moreover, a real-time polymerase chain reaction (PCR) assay, Western blot analysis, and an enzyme-linked immunosorbent assay (ELISA) were used to examine the osteogenesis gene and protein expression of dentin sialophosphoprotein (DSPP), dentin matrix acidic phosphoprotein 1 (DMP1), and osteocalcin (OCN). Finally, PLGA-lovastatin nanoparticles and mineral trioxide aggregate (MTA) were compared as direct pulp capping materials in Wistar rat teeth. The results showed that the median diameter of PLGA-lovastatin nanoparticles was 174.8 nm and the cumulative lovastatin release was 92% at the 44th day. PLGA-lovastatin nanoparticles demonstrated considerably a lower cytotoxicity than free lovastatin at 5, 9, and 13 days of culture. For ALP activity, the ALP amount of PLGA-lovastatin (100 μg/mL) was significantly higher than that of the other groups for 9 and 13 days of culture. The real-time PCR assay, Western blot analysis, and ELISA assay showed that PLGA-lovastatin (100 μg/mL) induced the highest mRNA and protein expression of DSPP, DMP1, and OCN in pulp cells. Histological evaluation of the animal studies revealed that MTA was superior to the PLGA-lovastatin in stimulating the formation of tubular dentin in an observation period of 2 weeks. However, in an observation period of 4 weeks, it was evident that the PLGA-lovastatin and MTA were competitive in the formation of tubular reparative dentin and a complete dentinal bridge.

Exploring the influence of Diels-Alder linker length on photothermal molecule release from gold nanorods.

PubMed

Vetterlein, Claudia; Vásquez, Rodrigo; Bolaños, Karen; Acosta, Gerardo A; Guzman, Fanny; Albericio, Fernando; Celis, Freddy; Campos, Marcelo; Kogan, Marcelo J; Araya, Eyleen

2018-06-01

We studied the photothermal release of carboxyfluorescein (CF) linked to the gold surface of gold nanorods (GNRs) by two Diels-Alder adducts of different lengths (n = 4 and n = 9). The functionalized GNRs were irradiated with infrared light to produce photothermal release of CF by a retro-Diels-Alder reaction. The adducts were chemisorbed on the GNRs and the functionalized nanoparticles were characterized by UV-vis, DLS, zeta potential and Raman and surface-enhanced Raman spectroscopy (SERS). On the basis of the degree of nanoparticle functionalization and the SERS results, we inferred the orientation of CF on the surface of the gold nanoparticle. Moreover, we determined the photothermal release profiles of CF from the gold surface by laser irradiation. The release was faster for the longer linker (n = 9). SERS revealed that, for the shorter linker (n = 4), molecules are oriented perpendicularly with respect to the gold surface, thereby maintaining the CF far from the surface. In contrast, the longer linker was observed to be tilted, thus maintaining CF close to the gold surface and therefore potentially favoring the photothermal transfer of energy. These results are relevant for the future development of the spatial and temporal controlled release of drugs by means of gold nanoparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

The tracer diffusion coefficient of soft nanoparticles in a linear polymer matrix

DOE PAGES

Imel, Adam E.; Rostom, Sahar; Holley, Wade; ...

2017-03-09

The diffusion properties of nanoparticles in polymer nanocomposites are largely unknown and are often difficult to determine experimentally. To address this shortcoming, we have developed a novel method to determine the tracer diffusion coefficient of soft polystyrene nanoparticles in a linear polystyrene matrix. Monitoring the interdiffusion of soft nanoparticles into a linear polystyrene matrix provides the mutual diffusion coefficient of this system, from which the tracer diffusion coefficient of the soft nanoparticle can be determined using the slow mode theory. Utilizing this protocol, the role of nanoparticle molecular weight and rigidity on its tracer diffusion coefficient is provided. These resultsmore » demonstrate that the diffusive behavior of these soft nanoparticles differ from that of star polymers, which is surprising since our recent studies suggest that the nanoparticle interacts with a linear polymer similarly to that of a star polymer. It appears that these deformable nanoparticles mostly closely mimic the diffusive behavior of fractal macromolecular architectures or microgels, where the transport of the nanoparticle relies on the cooperative motion of neighboring linear chains. Finally, the less cross-linked, and thus more deformable, nanoparticles diffuse faster than the more highly crosslinked nanoparticles, presumably because the increased deformability allows the nanoparticle to distort and fit into available space.« less

Nanotemplated polyelectrolyte films as porous biomolecular delivery systems

PubMed Central

Gand, Adeline; Hindié, Mathilde; Chacon, Diane; van Tassel, Paul R; Pauthe, Emmanuel

2014-01-01

Biomaterials capable of delivering controlled quantities of bioactive agents, while maintaining mechanical integrity, are needed for a variety of cell contacting applications. We describe here a nanotemplating strategy toward porous, polyelectrolyte-based thin films capable of controlled biomolecular loading and release. Films are formed via the layer-by-layer assembly of charged polymers and nanoparticles (NP), then chemically cross-linked to increase mechanical rigidity and stability, and finally exposed to tetrahydrofuran to dissolve the NP and create an intra-film porous network. We report here on the loading and release of the growth factor bone morphogenetic protein 2 (BMP-2), and the influence of BMP-2 loaded films on contacting murine C2C12 myoblasts. We observe nanotemplating to enable stable BMP-2 loading throughout the thickness of the film, and find the nanotemplated film to exhibit comparable cell adhesion, and enhanced cell differentiation, compared with a non-porous cross-linked film (where BMP-2 loading is mainly confined to the film surface). PMID:25482416

Nanotemplated polyelectrolyte films as porous biomolecular delivery systems. Application to the growth factor BMP-2.

PubMed

Gand, Adeline; Hindié, Mathilde; Chacon, Diane; Van Tassel, Paul R; Pauthe, Emmanuel

2014-01-01

Biomaterials capable of delivering controlled quantities of bioactive agents, while maintaining mechanical integrity, are needed for a variety of cell contacting applications. We describe here a nanotemplating strategy toward porous, polyelectrolyte-based thin films capable of controlled biomolecular loading and release. Films are formed via the layer-by-layer assembly of charged polymers and nanoparticles (NP), then chemically cross-linked to increase mechanical rigidity and stability, and finally exposed to tetrahydrofuran to dissolve the NP and create an intra-film porous network. We report here on the loading and release of the growth factor bone morphogenetic protein 2 (BMP-2), and the influence of BMP-2 loaded films on contacting murine C2C12 myoblasts. We observe nanotemplating to enable stable BMP-2 loading throughout the thickness of the film, and find the nanotemplated film to exhibit comparable cell adhesion, and enhanced cell differentiation, compared with a non-porous cross-linked film (where BMP-2 loading is mainly confined to the film surface).

Microelectromechanical (MEMS) manipulators for control of nanoparticle coupling interactions

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

Lopez, Daniel; Wiederrecht, Gary; Gosztola, David J.

A nanopositioning system for producing a coupling interaction between a first nanoparticle and a second nanoparticle. A first MEMS positioning assembly includes an electrostatic comb drive actuator configured to selectively displace a first nanoparticle in a first dimension and an electrode configured to selectively displace the first nanoparticle in a second dimensions. Accordingly, the first nanoparticle may be selectively positioned in two dimensions to modulate the distance between the first nanoparticle and a second nanoparticle that may be coupled to a second MEMS positioning assembly. Modulating the distance between the first and second nanoparticles obtains a coupling interaction between themore » nanoparticles that alters at least one material property of the nanoparticles applicable to a variety of sensing and control applications.« less

Enhanced response of a proteinase K-based conductometric biosensor using nanoparticles.

PubMed

Nouira, Wided; Maaref, Abderrazak; Elaissari, Hamid; Vocanson, Francis; Siadat, Maryam; Jaffrezic-Renault, Nicole

2014-07-23

Proteinases are involved in a multitude of important physiological processes, such as protein metabolism. For this reason, a conductometric enzyme biosensor based on proteinase K was developed using two types of nanoparticles (gold and magnetic). The enzyme was directly adsorbed on negatively charged nanoparticles and then deposited and cross-linked on a planar interdigitated electrode (IDE). The biosensor was characterized with bovine serum albumin (BSA) as a standard protein. Higher sensitivity was obtained using gold nanoparticles. The linear range for BSA determination was then from 0.5 to 10 mg/L with a maximum response of 154 µs. These results are greater than that found without any nanoparticles (maximum response of 10 µs). The limit of detection (LOD) was 0.3 mg/L. An inter-sensor reproducibility of 3.5% was obtained.

Silver Nanoparticle Oligonucleotide Conjugates Based on DNA with Triple Cyclic Disulfide Moieties

PubMed Central

Lee, Jae-Seung; Lytton-Jean, Abigail K. R.; Hurst, Sarah J.; Mirkin, Chad A.

2011-01-01

We report a new strategy for preparing silver nanoparticle oligonucleotide conjugates that are based upon DNA with cyclic disulfide-anchoring groups. These particles are extremely stable and can withstand NaCl concentrations up to 1.0 M. When silver nanoparticles functionalized with complementary sequences are combined, they assemble to form DNA-linked nanoparticle networks. This assembly process is reversible with heating and is associated with a red-shifting of the particle surface plasmon resonance and a concomitant color change from yellow to pale red. Analogous to the oligonucleotide-functionalized gold nanoparticles, these particles also exhibit highly cooperative binding properties with extremely sharp melting transitions. This work is an important step towards being able to use silver nanoparticle oligonucleotide conjugates for a variety of purposes, including molecular diagnostic labels, synthons in programmable materials synthesis approaches, and functional components for nanoelectronic and plasmonic devices. PMID:17571909

Fluxgate magnetorelaxometry for characterization of hydrogel polymerization kinetics and physical entrapment capacity.

PubMed

Heim, E; Harling, S; Ludwig, F; Menzel, H; Schilling, M

2008-05-21

Hydrogels have the potential for providing drug delivery systems with long release rates. The polymerization kinetics and the physical entrapment capacity of photo-cross-linked hydroxyethyl methacrylate hydroxyethylstarch hydrogels are investigated with a non-destructive method. For this purpose, superparamagnetic nanoparticles as replacements for biomolecules are used as probes. By analyzing their magnetic relaxation behavior, the amounts of physically entrapped and mobile nanoparticles can be determined. The hydrogels were loaded with five different concentrations of nanoparticles. Different methods of analysis of the relaxation curves and the influence of the microviscosity are discussed. This investigation allows one to optimize the UV light irradiation time and to determine the amount of physically entrapped nanoparticles in the hydrogel network. It was found that the polymerization kinetics is faster for decreasing nanoparticle concentration but not all nanoparticles can be physically entrapped in the network.

Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles

NASA Astrophysics Data System (ADS)

Lavado, Andrea S.; Chauhan, Veeren M.; Alhaj Zen, Amer; Giuntini, Francesca; Jones, D. Rhodri E.; Boyle, Ross W.; Beeby, Andrew; Chan, Weng C.; Aylott, Jonathan W.

2015-08-01

Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures. Electronic supplementary information (ESI) available: Materials and experimental methods for the synthesis of (1) positively charged alkyne functionalized nanoparticles (2) Zn(ii) and Cu(ii) centred porphyrin (3); conjugating porphyrins to alkyne-functionalized nanoparticles via click chemistry (4) nanoparticle characterisation (size charge and fluorescence), (5) synthesis of BPTFMC (6) hMSC collection, storage and preparation (7) delivery of porphyrin functionalized nanoparticles (8) staining mitochondria, cumulative ROS production and determination of nanoparticles subcellular localisation (9) fluorescence microscopy and controlled irradiation of hMSCs (10) flow cytometry and controlled irradiation using a custom built irradiator. In addition, results highlighting: (1) nanoparticles emission spectra, size and charge, (2) BPTFMC fluorescence response and (3) hMSCs following light irradiation using flow cytometry. See DOI: 10.1039/c5nr00795j

Adsorption and release of biocides with mesoporous silica nanoparticles

NASA Astrophysics Data System (ADS)

Popat, Amirali; Liu, Jian; Hu, Qiuhong; Kennedy, Michael; Peters, Brenton; Lu, Gao Qing (Max); Qiao, Shi Zhang

2012-01-01

In this proof-of-concept study, an agricultural biocide (imidacloprid) was effectively loaded into the mesoporous silica nanoparticles (MSNs) with different pore sizes, morphologies and mesoporous structures for termite control. This resulted in nanoparticles with a large surface area, tunable pore diameter and small particle size, which are ideal carriers for adsorption and controlled release of imidacloprid. The effect of pore size, surface area and mesoporous structure on uptake and release of imidacloprid was systematically studied. It was found that the adsorption amount and release profile of imidacloprid were dependent on the type of mesoporous structure and surface area of particles. Specifically, MCM-48 type mesoporous silica nanoparticles with a three dimensional (3D) open network structure and high surface area displayed the highest adsorption capacity compared to other types of silica nanoparticles. Release of imidacloprid from these nanoparticles was found to be controlled over 48 hours. Finally, in vivo laboratory testing on termite control proved the efficacy of these nanoparticles as delivery carriers for biopesticides. We believe that the present study will contribute to the design of more effective controlled and targeted delivery for other biomolecules.In this proof-of-concept study, an agricultural biocide (imidacloprid) was effectively loaded into the mesoporous silica nanoparticles (MSNs) with different pore sizes, morphologies and mesoporous structures for termite control. This resulted in nanoparticles with a large surface area, tunable pore diameter and small particle size, which are ideal carriers for adsorption and controlled release of imidacloprid. The effect of pore size, surface area and mesoporous structure on uptake and release of imidacloprid was systematically studied. It was found that the adsorption amount and release profile of imidacloprid were dependent on the type of mesoporous structure and surface area of particles. Specifically, MCM-48 type mesoporous silica nanoparticles with a three dimensional (3D) open network structure and high surface area displayed the highest adsorption capacity compared to other types of silica nanoparticles. Release of imidacloprid from these nanoparticles was found to be controlled over 48 hours. Finally, in vivo laboratory testing on termite control proved the efficacy of these nanoparticles as delivery carriers for biopesticides. We believe that the present study will contribute to the design of more effective controlled and targeted delivery for other biomolecules. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11691j

Enhanced nanoparticle size control by extending LaMer’s mechanism

DOE PAGES

Vreeland, Erika C.; Watt, John; Schober, Gretchen B.; ...

2015-08-17

The synthesis of well-defined nanoparticle materials has been an area of intense investigation, but size control in nanoparticle syntheses is largely empirical. Here, we introduce a general method for fine size control in the synthesis of nanoparticles by establishing steady state growth conditions through the continuous, controlled addition of precursor, leading to a uniform rate of particle growth. This approach, which we term the “extended LaMer mechanism” allows for reproducibility in particle size from batch to batch as well as the ability to predict nanoparticle size by monitoring the early stages of growth. We have demonstrated this method by applyingmore » it to a challenging synthetic system: magnetite nanoparticles. To facilitate this reaction, we have developed a reproducible method for synthesizing an iron oleate precursor that can be used without purification. As a result, we then show how such fine size control affects the performance of magnetite nanoparticles in magnetic hyperthermia.« less

Smooth and rapid microwave synthesis of MIL-53(Fe) including superparamagnetic γ-Fe2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Wengert, Simon; Albrecht, Joachim; Ruoss, Stephen; Stahl, Claudia; Schütz, Gisela; Schäfer, Ronald

2017-12-01

MIL-53(Fe) linked to superparamagnetic γ-Fe2O3 nanoparticles was created using time-efficient microwave synthesis. Intermediates as well as the final product have been characterized by Dynamic Light Scattering (DLS), Infrared Spectroscopy (FTIR) and Thermal Gravimetric Analysis (TGA). It is found that this route allows the production of Fe nanoparticles with typical sizes of about 80 nm that are embedded inside the metal-organic structures. Detailed magnetization measurements using SQUID magnetometry revealed a nearly reversible magnetization loop indicating essentially superparamagnetic behavior.

Effect of chitosan and thiolated chitosan coating on the inhibition behaviour of PIBCA nanoparticles against intestinal metallopeptidases

NASA Astrophysics Data System (ADS)

Bravo-Osuna, Irene; Vauthier, Christine; Farabollini, Alessandra; Millotti, Gioconda; Ponchel, Gilles

2008-12-01

Surface modified nanoparticles composed of poly(isobutylcyanoacrylate) (PIBCA) cores surrounded by a chitosan and thiolated chitosan gel layer were prepared and characterized in previous works. The presence of such biopolymers on the nanoparticle surface conferred those nanosystems interesting characteristics that might partially overcome the gastrointestinal enzymatic barrier, improving the oral administration of pharmacologically active peptides. In the present work, the antiprotease behaviour of this family of core-shell nanoparticles was in vitro tested against two model metallopeptidases present in the gastrointestinal tract (GIT): Carboxypeptidase A -CP A- (luminal protease) and Leucine Aminopeptidase M -LAP M- (membrane protease). As previous step, the zinc-binding capacity of these nanoparticles was evaluated. Interestingly, an improvement of both the zinc-binding capacity and the antiprotease effect of chitosan was observed when the biopolymers (chitosan and thiolated chitosan) were used as coating component of the core-shell nanoparticles, in comparison with their behaviour in solution, thanks to the different biopolymer chains rearrangement. The presence of amino, hydroxyl and thiol groups on the nanoparticle surface promoted zinc binding and hence the inhibition of the metallopeptidases analysed. On the contrary, the occurrence of a cross-linked structure in the gel layer surrounding the PIBCA cores of thiolated formulations, due to the formation of interchain and intrachain disulphide bonds, partially limited the inhibition of the proteases. The low accessibility of cations to the active groups of the cross-linked polymeric shell was postulated as a possible explanation of this behaviour. Results obtained in this work make this family of surface-modified nanocarriers promising candidates for the successfull administration of pharmacologically active peptides and proteins by the oral route.

Nanoparticle-protein complexes mimicking corona formation in ocular environment.

PubMed

Jo, Dong Hyun; Kim, Jin Hyoung; Son, Jin Gyeong; Dan, Ki Soon; Song, Sang Hoon; Lee, Tae Geol; Kim, Jeong Hun

2016-12-01

Nanoparticles adsorb biomolecules to form corona upon entering the biological environment. In this study, tissue-specific corona formation is provided as a way of controlling protein interaction with nanoparticles in vivo. In the vitreous, the composition of the corona was determined by the electrostatic and hydrophobic properties of the associated proteins, regardless of the material (gold and silica) or size (20- and 100-nm diameter) of the nanoparticles. To control protein adsorption, we pre-incubate 20-nm gold nanoparticles with 5 selectively enriched proteins from the corona, formed in the vitreous, to produce nanoparticle-protein complexes. Compared to bare nanoparticles, nanoparticle-protein complexes demonstrate improved binding to vascular endothelial growth factor (VEGF) in the vitreous. Furthermore, nanoparticle-protein complexes retain in vitro anti-angiogenic properties of bare nanoparticles. In particular, priming the nanoparticles (gold and silica) with tissue-specific corona proteins allows nanoparticle-protein complexes to exert better in vivo therapeutic effects by higher binding to VEGF than bare nanoparticles. These results suggest that controlled corona formation that mimics in vivo processes may be useful in the therapeutic use of nanomaterials in local environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Novel biocompatible hydrogel nanoparticles: generation and size-tuning of nanoparticles by the formation of micelle templates obtained from thermo-responsive monomers mixtures

NASA Astrophysics Data System (ADS)

Khandadash, Raz; Machtey, Victoria; Shainer, Inbal; Gottlieb, Hugo E.; Gothilf, Yoav; Ebenstein, Yuval; Weiss, Aryeh; Byk, Gerardo

2014-12-01

Biocompatible hydrogel nanoparticles are prepared by polymerization and cross-linking of N-isopropyl acrylamide in a micelle template formed by block copolymers macro-monomers at high temperature. Different monomer ratios form, at high temperature, well-defined micelles of different sizes which are further polymerized leading to nanoparticles with varied sizes from 20 to 390 nm. Physico-chemical characterization of the nanoparticles demonstrates their composition and homogeneity. The NPs were tested in vitro and in vivo biocompatibility assays, and their lack of toxicity was proven. The NPs can be labeled with fluorescent probes, and their intracellular fate can be visualized and quantified using confocal microscopy. Their uptake by live stem cells and distribution in whole developing animals is reported. On the basis of our results, a mechanism of nanoparticle formation is suggested. The lack of toxicity makes these nanoparticles especially attractive for biological applications such as screening and bio-sensing.

Zirconium oxocluster/polymer hybrid nanoparticles prepared by photoactivated miniemulsion copolymerization

NASA Astrophysics Data System (ADS)

Benedetti, Cesare; Flouda, Paraskevi; Antonello, Alice; Rosenauer, Christine; Pérez-Pla, Francisco F.; Landfester, Katharina; Gross, Silvia; Muñoz-Espí, Rafael

2017-09-01

The photoactivated free radical miniemulsion copolymerization of methyl methacrylate (MMA) and the zirconium oxocluster Zr4O2(methacrylate)12 is used as an effective and fast preparation method for polymer/inorganic hybrid nanoparticles. The oxoclusters, covalently anchored to the polymer network, act as metal-organic cross-linkers, thus improving the thermomechanical properties of the resulting hybrid nanoparticles. Benzoin carbonyl organic compounds were used as photoinitiators. The obtained materials are compared in terms of cross-linking, effectiveness of cluster incorporation, and size distribution with the analogous nanoparticles produced by using conventional thermally induced free radical miniemulsion copolymerization. The kinetics of the polymerization process in the absence and in the presence of the oxocluster is also investigated.

Development and design of nanomaterial reagents in conjunction with new methods for their synthetic applications

NASA Astrophysics Data System (ADS)

Kwaramba, Farai Brian

This Ph.D. deals with the integration of nanotechnology with organometallic/ organic synthetic technologies. The first part of this research sought to develop a library of novel molecular gears programmed to exploit photo-switching and electrostatic repulsion to control the molecular rotation of covalently linked triptypyrazines. Incorporation of these two modes allows for control of triptycene based gear systems using unexplored external methods. The triptypyrazine was an attractive scaffold because of its intrinsic pH and electrochemical activity, thus providing a novel construct for controlling molecular motion. This design finds relevance in the fabrication of nano-electromechanical devices and understanding controlled molecular motion. This Ph.D. also sought to address the need to generate and recycle low cost hydrosilylation catalysts. Metal nanoparticle catalysts can potentially meet this need due to their high surface area and reactivity. Their morphology and surface texture provide avenues for selectivity in reactions. Metal-nanoparticles on a silicon matrix can be formed by reducing metal salts with silicon hydrides. Investigations towards iron-nanoparticle catalyzed hydrosilylation of unsaturated bonds were conducted. Furthermore, this research sought to develop highly functionalized silanes, as guiding scaffolds for generating chiral silicon hydrides. Fabrication of metal-nanoparticle catalysts with the same, could install surface definition on these heterogeneous green catalysts, thus allowing selectivity in their catalysis. A bottom up approach to nanofabrication, started with the generation of a library of highly functionalized alkynyl-silane building blocks using the hydrosilylation reaction. Hydrosilylation of carbon-carbon and carbon-heteroatom unsaturated bonds has proven to be an important reaction in organic syntheses. Additionally, silicon tethers have been utilized in complex organic syntheses as a way to increase reaction rates, and selectivity. The most commonly employed silicon tethers have been disiloxanes followed by siloxanes, then silanes. Of these methods the synthesis and utilization of tethered silyl-alkynes was limited. To address this gap, this work developed methodology to prepare tethered silyl alkynes through a hydrosilylation reaction. It was established that [IrCl(COD)]2 in the presence of excess COD can selectively catalyze the hydrosilylation of alkenes with alkynyl-silanes. This approach overrides traditional hydrosilylation catalysts' reactivity trends.

EDITORIAL: Plasmas and plasmons: links in nanosilver Plasmas and plasmons: links in nanosilver

NASA Astrophysics Data System (ADS)

Demming, Anna

2013-03-01

Silver has long been valued not just for its rarity but also for its broad ranging attractive properties as a conductor, catalyst and antimicrobial agent, among others. In nanoscale structures, silver takes on a number of additional attributes, as properties such as antimicrobial activity show size dependence. In addition plasmonic properties are exhibited, which enhance local electromagnetic fields and can be hugely beneficial in sensing and imaging applications. As a result silver nanoparticles are increasingly in demand. In this issue researchers describe a microplasma-assisted electrochemical synthesis that allows excellent control over the size and spacing of the resulting particles, which are important parameters for optimizing their performance in device applications [1]. Wet chemistry [2] and lithography [3] are common processes for silver nanoparticle synthesis. However, other methods are constantly in development. Biosynthesis approaches have been attracting increasing interest as more environmentally friendly alternatives. Takayuki Kuwabara and colleagues at Xiamen University in China used the sundried biomass of Cinnamomum camphora leaf to reduce silver nitrate [4], demonstrating a cost-efficient alternative to conventional methods which might also be suitable for large-scale production. At Zhejiang Normal University researchers noted that the abasic site (AP site) in the DNA duplex can act as a capping scaffold in the generation of fluorescent silver nanoclusters [5]. In addition the resulting fluorescence of the nanocrystals can be used for detecting DNA single-nucleotide polymorphism. Researchers in Malaysia have also noted the potential sensing applications of nanoparticles of another noble metal for swine DNA [6]. They observed that single-strand DNA was absorbed on gold nanoparticles and led to a colour shift from pinkish-red to grey-purple. The shift was the result of a reduction in the surface plasmon resonance peak at 530 nm and new features appearing in the 620-800 nm regions of the absorption spectra. A number of research groups have investigated the possibility of exploiting the plasmonic properties of silver and gold nanostructures for optoelectronic devices [7-9]. The advantages can be quite substantial. Researchers in Korea successfully used silver nanoparticles to obtain a 38% increase in performance of blue LEDs by using silver nanoparticles embedded in p-GaN [10]. The researchers attribute the improvement to an increase in the spontaneous emission rate through resonance coupling between the excitons in multiple quantum wells and localized surface plasmons in the silver nanoparticles. In their work reported in this issue Kostya Ostrikov and his co-authors bridge the link between microplasma-assisted electrochemical process parameters and the plasmonic response. As they point out, 'This is an important experimental step towards bringing together plasma chemistry and plasmonics' [1]. All-gas-phase plasma approaches have already been demonstrated for the synthesis of nanoparticles of other metals. X D Pi and colleagues from the University of Minnesota demonstrated how one simple gas-phase process could produce stable silicon nanocrystal emitters with tailored size and surface functionalization [11]. Previously silicon nanocrystals had been prone to emission instabilities in air. Now Ostrikov and colleagues at the University of Sydney, CSIRO Materials Science and Engineering in Australia and the Key Laboratory for Laser Plasmas in China have studied microplasma-assisted electrochemical synthesis of Ag nanoparticles for plasmonic applications [1]. The synthesis uses moderate temperatures and atmospheric pressures and does not involve any toxic reducing agents. In addition they demonstrate how it allows control over nanoparticle size and interparticle spacing to optimize performance in device applications. Despite the overlap in plasma physics and the origins of plasmonic phenomena, studies of the relationship between plasma electrochemical synthesis and the plasmonic properties of nanoparticles have been limited until now. Yet Kostya Ostrikov and colleagues place particular emphasis on the potential of research at 'the intersection of reactive plasma chemistry and plasmonics'. While navigating the maze of intertwining disciplines that feed into nanotechnology research can be daunting, as this research highlights, great insights and advances may be gained where the different strands of research connect. References [1] Huang X Z, Zhong X X, Lu Y, Li Y S, Rider A E, Furman S A and Ostrikov K 2013 Plasmonic Ag nanoparticles via environment-benign atmospheric microplasma electrochemistry Nanotechnology 24 095604 [2] Sun Y and Xia Y 2002 Shape-controlled synthesis of gold and silver nanoparticles Science 298 2176-9 [3] Hulteen J C, Treichel D A, Smith M T, Duval M L, Jensen T R and Van Duyne R P 1999 Nanosphere lithography: size-tunable silver nanoparticle and surface cluster arrays J. Phys. Chem. B 103 3854-63 [4] Huang J et al 2007 Biosynthesis of silver and gold nanoparticles by novel sundried Cinnamomum camphora leaf Nanotechnology 18 105104 [5] Ma K, Cui Q, Liu G, Wu F, Xu S and Shao Y 2011 DNA abasic site-directed formation of fluorescent silver nanoclusters for selective nucleobase recognition Nanotechnology 22 305502 [6] Ali M E, Hashim U, Mustafa S, Che Man Y B, Yusop M H M, Bari M F, Islam Kh N and Hasan M F 2011 Nanoparticle sensor for label free detection of swine DNA in mixed biological samples Nanotechnology 22 195503 [7] Berini P, Olivieri A and Chen C 2012 Thin Au surface plasmon waveguide Schottky detectors on p-Si Nanotechnology 23 444011 [8] Reilly T H III, Van De Lagemaat J, Tenent R C, Morfa A J and Rowlen K L 2008 Surface-plasmon enhanced transparent electrodes in organic photovoltaics Appl. Phys. Lett. 92 243304 [9] Bialiayeu A, Bottomley A, Prezgot D, Ianoul A and Albert J 2012 Plasmon-enhanced refractometry using silver nanowire coatings on tilted fibre Bragg gratings Nanotechnology 23 444012 [10] Cho C-Y, Kwon M-K, Lee S-J, Han S-H, Kang J-W, Kang S-E, Lee D-Y and Park S-J 2010 Surface plasmon-enhanced light-emitting diodes using silver nanoparticles embedded in p-GaN Nanotechnology 21 205201 [11] Pi X D, Liptak R W, Deneen N J, Wells N P, Carter C B, Campbell S A and Kortshagen U 2008 Air-stable full-visible-spectrum emission from silicon nanocrystals synthesized by an all-gas-phase plasma approach Nanotechnology 19 245603

Functionalization of Mechanochemically Passivated Germanium Nanoparticles via "Click" Chemistry

NASA Astrophysics Data System (ADS)

Purkait, Tapas Kumar

Germanium nanoparticles (Ge NPs) may be fascinating for their electronic and optoelectronic properties, as the band gap of Ge NPs can be tuned from the infrared into the visible range of solar spectru. Further functionalization of those nanoparticles may potentially lead to numerous applications ranging from surface attachment, bioimaging, drug delivery and nanoparticles based devices. Blue luminescent germanium nanoparticles were synthesized from a novel top-down mechanochemical process using high energy ball milling (HEBM) of bulk germanium. Various reactive organic molecules (such as, alkynes, nitriles, azides) were used in this process to react with fresh surface and passivate the surface through Ge-C or Ge-N bond. Various purification process, such as gel permeation chromatography (GPC), Soxhlet dailysis etc. were introduced to purify nanoparticles from molecular impurities. A size separation technique was developed using GPC. The size separated Ge NPs were characterize by TEM, small angle X-ray scattering (SAXS), UV-vis absorption and photoluminescence (PL) emission spectroscopy to investigate their size selective properties. Germanium nanoparticles with alkyne termini group were prepared by HEBM of germanium with a mixture of n-alkynes and alpha, o-diynes. Additional functionalization of those nanoparticles was achieved by copper(I) catalyzed azide-alkyne "click" reaction. A variety of organic and organometallic azides including biologically important glucals have been reacted in this manner resulting in nanopartilces adorned with ferrocenyl, trimethylsilyl, and glucal groups. Additional functionalization of those nanoparticles was achieved by reactions with various azides via a Cu(I) catalyzed azide-alkyne "click" reaction. Various azides, including PEG derivatives and cylcodextrin moiety, were grafted to the initially formed surface. Globular nanoparticle arrays were formed through interparticle linking via "click" chemistry or "host-guest" chemistry. Copper(I) catalyzed "click" chemistry also can be explored with azido-terminated Ge NPs which were synthesized by azidation of chloro-terminated Ge NPs. Water soluble PEGylated Ge NPs were synthesized by "click" reaction for biological application. PEGylated Ge NP clusters were prepared using alpha, o-bis alkyno or bis-azido polyethylene glycol (PEG) derivatives by copper catalyzed "click" reaction via inter-particle linking. These nanoparticles were further functionalized by azido beta-cyclodextrin (beta-CD) and azido adamantane via alkyne-azide "click" reactions. Nanoparticle clusters were made from the functionalized Ge NPs by "host-guest" chemistry of beta-CD functionalized Ge NPs either with adamantane functionalized Ge NPs or fullerene, C60.

Nanoparticle (star polymer) delivery of nitric oxide effectively negates Pseudomonas aeruginosa biofilm formation.

PubMed

Duong, Hien T T; Jung, Kenward; Kutty, Samuel K; Agustina, Sri; Adnan, Nik Nik M; Basuki, Johan S; Kumar, Naresh; Davis, Thomas P; Barraud, Nicolas; Boyer, Cyrille

2014-07-14

Biofilms are increasingly recognized as playing a major role in human infectious diseases, as they can form on both living tissues and abiotic surfaces, with serious implications for applications that rely on prolonged exposure to the body such as implantable biomedical devices or catheters. Therefore, there is an urgent need to develop improved therapeutics to effectively eradicate unwanted biofilms. Recently, the biological signaling molecule nitric oxide (NO) was identified as a key regulator of dispersal events in biofilms. In this paper, we report a new class of core cross-linked star polymers designed to store and release nitric oxide, in a controlled way, for the dispersion of biofilms. First, core cross-linked star polymers were prepared by reversible addition-fragmentation chain transfer polymerization (RAFT) via an arm first approach. Poly(oligoethylene methoxy acrylate) chains were synthesized by RAFT polymerization, and then chain extended in the presence of 2-vinyl-4,4-dimethyl-5-oxazolone monomer (VDM) with N,N-methylenebis(acrylamide) employed as a cross-linker to yield functional core cross-linked star polymers. Spermine was successfully attached to the star core by reaction with VDM. Finally, the secondary amine groups were reacted with NO gas to yield NO-core cross-linked star polymers. The core cross-linked star polymers were found to release NO in a controlled, slow delivery in bacterial cultures showing great efficacy in preventing both cell attachment and biofilm formation in Pseudomonas aeruginosa over time via a nontoxic mechanism, confining bacterial growth to the suspended liquid.

Imaging Metastasis Using an Integrin-Targeting Chain-Shaped Nanoparticle

PubMed Central

Peiris, Pubudu M.; Toy, Randall; Doolittle, Elizabeth; Pansky, Jenna; Abramowski, Aaron; Tam, Morgan; Vicente, Peter; Tran, Emily; Hayden, Elliott; Camann, Andrew; Mayer, Aaron; Erokwu, Bernadette O.; Berman, Zachary; Wilson, David; Baskaran, Harihara; Flask, Chris A.; Keri, Ruth A.; Karathanasis, Efstathios

2012-01-01

While the enhanced permeability and retention effect may promote the preferential accumulation of nanoparticles into well-vascularized primary tumors, it is ineffective in the case of metastases hidden within a large population of normal cells. Due to their small size, high dispersion to organs, and low vascularization, metastatic tumors are less accessible to targeted nanoparticles. To tackle these challenges, we designed a nanoparticle for vascular targeting based on an αvβ3 integrin-targeted nanochain particle composed of four iron oxide nanospheres chemically linked in a linear assembly. The chain-shaped nanoparticles enabled enhanced ‘sensing’ of the tumor-associated remodeling of the vascular bed offering increased likelihood of specific recognition of metastatic tumors. Compared to spherical nanoparticles, the chain-shaped nanoparticles resulted in superior targeting of αvβ3 integrin due to geometrically enhanced multivalent docking. We performed multimodal in vivo imaging (Fluorescence Molecular Tomography and Magnetic Resonance Imaging) in a non-invasive and quantitative manner, which showed that the nanoparticles targeted metastases in the liver and lungs with high specificity in a highly aggressive breast tumor model in mice. PMID:23005348

Fabrication and in vitro release behavior of a novel antibacterial coating containing halogenated furanone-loaded poly(L-lactic acid) nanoparticles on microarc-oxidized titanium

PubMed Central

Cheng, Yicheng; Wu, Jiang; Gao, Bo; Zhao, Xianghui; Yao, Junyan; Mei, Shenglin; Zhang, Liang; Ren, Huifang

2012-01-01

Background Dental implants have become increasingly common for the management of missing teeth. However, peri-implant infection remains a problem, is usually difficult to treat, and may lead eventually to dental implant failure. The aim of this study was to fabricate a novel antibacterial coating containing a halogenated furanone compound, ie, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone (BBF)-loaded poly(L-lactic acid) (PLLA) nanoparticles on microarc-oxidized titanium and to evaluate its release behavior in vitro. Methods BBF-loaded PLLA nanoparticles were prepared using the emulsion solvent-evaporation method, and the antibacterial coating was fabricated by cross-linking BBF-loaded PLLA nanoparticles with gelatin on microarc-oxidized titanium. Results The BBF-loaded PLLA nanoparticles had a small particle size (408 ± 14 nm), a low polydispersity index (0.140 ± 0.008), a high encapsulation efficiency (72.44% ± 1.27%), and a fine spherical shape with a smooth surface. The morphology of the fabricated antibacterial coating showed that the BBF-loaded PLLA nanoparticles were well distributed in the pores of the microarc oxidation coating, and were cross-linked with each other and the wall pores by gelatin. The release study indicated that the antibacterial coating could achieve sustained release of BBF for 60 days, with a slight initial burst release during the first 4 hours. Conclusion The novel antibacterial coating fabricated in this study is a potentially promising method for prevention of early peri-implant infection. PMID:23152682

Magnetic mesoporous silica nanoparticles for potential delivery of chemotherapeutic drugs and hyperthermia.

PubMed

Tao, Cuilian; Zhu, Yufang

2014-11-07

Magnetic mesoporous silica (MMS) nanoparticles with controllable magnetization have been synthesized by encapsulating Fe3O4 nanoparticles in a mesoporous silica matrix. The structure, magnetic heating capacity and drug delivery ability of MMS nanoparticles were evaluated. The results showed that MMS nanoparticles had an average particle size of 150 nm and showed low cytotoxicity and efficient cell uptake ability. MMS nanoparticles exhibited a sustained drug release in the medium of pH 5.0, but a very slow release in the medium of pH 7.4. On the other hand, MMS nanoparticles could controllably generate heat to reach the hyperthermia temperature within a short time upon exposure to an alternating magnetic field due to the superparamagnetic behavior and controllable magnetization. Therefore, MMS nanoparticles could provide a promising multifunctional platform for the combination of chemotherapy and hyperthermia for cancer therapy.

Suppression of activation energy and superconductivity by the addition of Al{sub 2}O{sub 3} nanoparticles in CuTl-1223 matrix

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

Jabbar, Abdul; Qasim, Irfan; Mumtaz, M.

2014-05-28

Low anisotropic (Cu{sub 0.5}Tl{sub 0.5})Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10−δ} (CuTl-1223) high T{sub c} superconducting matrix was synthesized by solid-state reaction and Al{sub 2}O{sub 3} nanoparticles were prepared separately by co-precipitation method. Al{sub 2}O{sub 3} nanoparticles were added with different concentrations during the final sintering cycle of CuTl-1223 superconducting matrix to get the required (Al{sub 2}O{sub 3}){sub y}/CuTl-1223, y = 0.0, 0.5, 0.7, 1.0, and 1.5 wt. %, composites. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray, and dc-resistivity (ρ) measurements. The activation energy and superconductivity were suppressed with increasing concentration of Al{sub 2}O{sub 3} nanoparticles in (CuTl-1223) matrix.more » The XRD analysis showed that the addition of Al{sub 2}O{sub 3} nanoparticles did not affect the crystal structure of the parent CuTl-1223 superconducting phase. The suppression of activation energy and superconducting properties is most probably due to weak flux pinning in the samples. The possible reason of weak flux pinning is reduction of weak links and enhanced inter-grain coupling due to the presence of Al{sub 2}O{sub 3} nanoparticles at the grain boundaries. The presence of Al{sub 2}O{sub 3} nanoparticles at the grain boundaries possibly reduced the number of flux pinning centers, which were present in the form of weak links in the pure CuTl-1223 superconducting matrix. The increase in the values of inter-grain coupling (α) deduced from the fluctuation induced conductivity analysis with the increased concentration of Al{sub 2}O{sub 3} nanoparticles is a theoretical evidence of improved inter-grain coupling.« less

Conductance oscillations in molecularly linked Au nanoparticle film-superconductor systems.

PubMed

Dunford, Jeffrey L; Dhirani, Al-Amin

2008-01-16

Charge transport across a disordered normal-superconductor (DN-S) interface was studied using a macroscopic, molecularly linked Au nanoparticle film as the DN component. Low-temperature conductance versus voltage and magnetic field exhibit zero-bias and zero-field peaks, respectively. Importantly, the latter typically exhibit superimposed oscillations. Such oscillations are rarely seen in other DN-S systems and are remarkable given their robustness in these macroscopic films and interfaces. A number of observations indicate that conductance peaks and oscillations arise due to a 'reflectionless tunnelling' process. Scattering length scales extracted from the data using a reflectionless tunnelling picture are consistent with literature values. Factors resulting in the observation of oscillations in this system are discussed.

Protein Corona Analysis of Silver Nanoparticles Links to Their Cellular Effects.

PubMed

Juling, Sabine; Niedzwiecka, Alicia; Böhmert, Linda; Lichtenstein, Dajana; Selve, Sören; Braeuning, Albert; Thünemann, Andreas F; Krause, Eberhard; Lampen, Alfonso

2017-11-03

The breadth of applications of nanoparticles and the access to food-associated consumer products containing nanosized materials lead to oral human exposure to such particles. In biological fluids nanoparticles dynamically interact with biomolecules and form a protein corona. Knowledge about the protein corona is of great interest for understanding the molecular effects of particles as well as their fate inside the human body. We used a mass spectrometry-based toxicoproteomics approach to elucidate mechanisms of toxicity of silver nanoparticles and to comprehensively characterize the protein corona formed around silver nanoparticles in Caco-2 human intestinal epithelial cells. Results were compared with respect to the cellular function of proteins either affected by exposure to nanoparticles or present in the protein corona. A transcriptomic data set was included in the analyses in order to obtain a combined multiomics view of nanoparticle-affected cellular processes. A relationship between corona proteins and the proteomic or transcriptomic responses was revealed, showing that differentially regulated proteins or transcripts were engaged in the same cellular signaling pathways. Protein corona analyses of nanoparticles in cells might therefore help in obtaining information about the molecular consequences of nanoparticle treatment.

A facile synthesis of dynamic, shape-changing polymer particles.

PubMed

Klinger, Daniel; Wang, Cynthia X; Connal, Luke A; Audus, Debra J; Jang, Se Gyu; Kraemer, Stephan; Killops, Kato L; Fredrickson, Glenn H; Kramer, Edward J; Hawker, Craig J

2014-07-01

We herein report a new facile strategy to ellipsoidal block copolymer nanoparticles that exhibit a pH-triggered anistropic swelling profile. In a first step, elongated particles with an axially stacked lamellae structure are selectively prepared by utilizing functional surfactants to control the phase separation of symmetric polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) in dispersed droplets. In a second step, the dynamic shape change is realized by cross-linking the P2VP domains, thereby connecting glassy PS discs with pH-sensitive hydrogel actuators. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supercooling of Water Controlled by Nanoparticles and Ultrasound

NASA Astrophysics Data System (ADS)

Cui, Wei; Jia, Lisi; Chen, Ying; Li, Yi'ang; Li, Jun; Mo, Songping

2018-05-01

Nanoparticles, including Al2O3 and SiO2, and ultrasound were adopted to improve the solidification properties of water. The effects of nanoparticle concentration, contact angle, and ultrasonic intensity on the supercooling degree of water were investigated, as well as the dispersion stability of nanoparticles in water during solidification. Experimental results show that the supercooling degree of water is reduced under the combined effect of ultrasound and nanoparticles. Consequently, the reduction of supercooling degree increases with the increase of ultrasonic intensity and nanoparticle concentration and decrease of contact angle of nanoparticles. Moreover, the reduction of supercooling degree caused by ultrasound and nanoparticles together do not exceed the sum of the supercooling degree reductions caused by ultrasound and nanoparticles separately; the reduction is even smaller than that caused by ultrasound individually under certain conditions of controlled nanoparticle concentration and contact angle and ultrasonic intensity. The dispersion stability of nanoparticles during solidification can be maintained only when the nanoparticles and ultrasound together show a superior effect on reducing the supercooling degree of water to the single operation of ultrasound. Otherwise, the aggregation of nanoparticles appears in water solidification, which results in failure. The relationships among the meaningful nanoparticle concentration, contact angle, and ultrasonic intensity, at which the requirements of low supercooling and high stability could be satisfied, were obtained. The control mechanisms for these phenomena were analyzed.

[Application of subserosal injection of carbon nanoparticles via infusion needle to label lymph nodes in laparoscopic radical gastrectomy].

PubMed

Chen, Hongyuan; Wang, Yanan; Xue, Fangqin; Yu, Jiang; Hu, Yanfeng; Liu, Hao; Yan, Jun; Li, Guoxin

2014-05-01

To explore the feasibility of subserosal injection of carbon nanoparticle via venous infusion needle to label lymph node and its application value in laparoscopic radical gastrectomy. Forty patients with gastric cancer were randomly divided into two groups (carbon nanoparticle group and control group). Subserosal injection of carbon nanoparticle around the tumor was performed via venous infusion needle laparoscopically at the beginning of surgery in carbon nanoparticles group, while the patients routinely underwent laparoscopic radical gastrectomy in control group. Results of harvested lymph nodes were compared between the two groups. The perioperative complications and the side effect of carbon nanoparticle were also evaluated. The average number of harvested lymph node in carbon nanoparticle group (31.7±7.6) was significantly higher than that in control group (19.8±6.1, P<0.05). The proportion of harvested small node (< 5 mm) in carbon nanoparticles group(61.0%) was higher than that in control group(43.3%, P<0.01). The mean harvest time in carbon nanoparticle group [(23.5±4.8) min] was shorter than that in control group [(32.6±5.5) min, P<0.05]. The rate of black-dyed harvested lymph node was 61.9% and the metastasis rate of black-dyed lymph node was 23.0% in carbon nanoparticle group, which were significantly higher than those without black-dyed(6.2%, P<0.05) and those in control group (15.7%, P<0.05). The operative time and perioperative complications were not significantly different between the two groups, and no serious side effect caused by carbon nanoparticle was observed. Subserosal injection of carbon nanoparticle via venous infusion needle to label lymph nodes during laparoscopic radical gastrectomy is safe and feasible. It can increase the number of harvested lymph node, especially the small node.

Albumin-based nanoparticles as methylprednisolone carriers for targeted delivery towards the neonatal Fc receptor in glomerular podocytes

PubMed Central

Wu, Lin; Chen, Mingyu; Mao, Huijuan; Wang, Ningning; Zhang, Bo; Zhao, Xiufen; Qian, Jun; Xing, Changying

2017-01-01

Glucocorticoids (GCs) are commonly used in the treatment of nephrotic syndrome. However, high doses and long periods of GC therapy can result in severe side effects. The present study aimed to selectively deliver albumin-methylprednisolone (MP) nanoparticles towards glomerular podocytes, which highly express the specific neonatal Fc receptor (FcRn) of albumin. Bovine serum albumin (BSA) was labeled with a fluorescent dye and linked with modified MP via an amide bond. The outcome nanoparticle named BSA633-MP showed a uniform size with a diameter of approximately 10 nm and contained 12 drug molecules on average. The nanoconjugates were found to be stable at pH 7.4 and acid-sensitive at pH 4.0, with approximately 72% release of the MP drug after 48 h of incubation. The nanoparticle demonstrated a 36-fold uptake in receptor-specific cellular delivery in the FcRn-expressing human podocytes compared to the uptake in the non-FcRn-expressing control cells. Co-localization further confirmed that uptake of the nanoconjugates involved receptor-mediated endocytosis followed by lysosome associated transportation. In vitro cellular experiments indicated that the BSA633-MP ameliorated puromycin aminonucleoside-induced podocyte apoptosis. Moreover, in vivo fluorescence molecular imaging showed that BSA633-MP was mainly accumulated in the liver and kidney after intravenous dosing for 24 h. Collectively, this study may provide an approach for the effective and safe therapy of nephrotic syndrome. PMID:28259932

Development of polymeric-cationic peptide composite nanoparticles, a nanoparticle-in-nanoparticle system for controlled gene delivery.

PubMed

Jain, Arvind K; Massey, Ashley; Yusuf, Helmy; McDonald, Denise M; McCarthy, Helen O; Kett, Vicky L

2015-01-01

We report the formulation of novel composite nanoparticles that combine the high transfection efficiency of cationic peptide-DNA nanoparticles with the biocompatibility and prolonged delivery of polylactic acid-polyethylene glycol (PLA-PEG). The cationic cell-penetrating peptide RALA was used to condense DNA into nanoparticles that were encapsulated within a range of PLA-PEG copolymers. The composite nanoparticles produced exhibited excellent physicochemical properties including size <200 nm and encapsulation efficiency >80%. Images of the composite nanoparticles obtained with a new transmission electron microscopy staining method revealed the peptide-DNA nanoparticles within the PLA-PEG matrix. Varying the copolymers modulated the DNA release rate >6 weeks in vitro. The best formulation was selected and was able to transfect cells while maintaining viability. The effect of transferrin-appended composite nanoparticles was also studied. Thus, we have demonstrated the manufacture of composite nanoparticles for the controlled delivery of DNA.

Development of polymeric–cationic peptide composite nanoparticles, a nanoparticle-in-nanoparticle system for controlled gene delivery

PubMed Central

Jain, Arvind K; Massey, Ashley; Yusuf, Helmy; McDonald, Denise M; McCarthy, Helen O; Kett, Vicky L

2015-01-01

We report the formulation of novel composite nanoparticles that combine the high transfection efficiency of cationic peptide-DNA nanoparticles with the biocompatibility and prolonged delivery of polylactic acid–polyethylene glycol (PLA-PEG). The cationic cell-penetrating peptide RALA was used to condense DNA into nanoparticles that were encapsulated within a range of PLA-PEG copolymers. The composite nanoparticles produced exhibited excellent physicochemical properties including size <200 nm and encapsulation efficiency >80%. Images of the composite nanoparticles obtained with a new transmission electron microscopy staining method revealed the peptide-DNA nanoparticles within the PLA-PEG matrix. Varying the copolymers modulated the DNA release rate >6 weeks in vitro. The best formulation was selected and was able to transfect cells while maintaining viability. The effect of transferrin-appended composite nanoparticles was also studied. Thus, we have demonstrated the manufacture of composite nanoparticles for the controlled delivery of DNA. PMID:26648722

Sectorial oscillation of acoustically levitated nanoparticle-coated droplet

NASA Astrophysics Data System (ADS)

Zang, Duyang; Chen, Zhen; Geng, Xingguo

2016-01-01

We have investigated the dynamics of a third mode sectorial oscillation of nanoparticle-coated droplets using acoustic levitation in combination with active modulation. The presence of nanoparticles at the droplet surface changes its oscillation amplitude and frequency. A model linking the interfacial rheology and oscillation dynamics has been proposed in which the compression modulus ɛ of the particle layer is introduced into the analysis. The ɛ obtained with the model is in good agreement with that obtained by the Wilhelmy plate approach, highlighting the important role of interfacial rheological properties in the sectorial oscillation of droplets.

Tiny Grains Give Huge Gains: Nanocrystal–Based Signal Amplification for Biomolecule Detection

PubMed Central

Tong, Sheng; Ren, Binbin; Zheng, Zhilan; Shen, Han; Bao, Gang

2013-01-01

Nanocrystals, despite their tiny sizes, contain thousands to millions of atoms. Here we show that the large number of atoms packed in each metallic nanocrystal can provide a huge gain in signal amplification for biomolecule detection. We have devised a highly sensitive, linear amplification scheme by integrating the dissolution of bound nanocrystals and metal-induced stoichiometric chromogenesis, and demonstrated that signal amplification is fully defined by the size and atom density of nanocrystals, which can be optimized through well-controlled nanocrystal synthesis. Further, the rich library of chromogenic reactions allows implementation of this scheme in various assay formats, as demonstrated by the iron oxide nanoparticle linked immunosorbent assay (ILISA) and blotting assay developed in this study. Our results indicate that, owing to the inherent simplicity, high sensitivity and repeatability, the nanocrystal based amplification scheme can significantly improve biomolecule quantification in both laboratory research and clinical diagnostics. This novel method adds a new dimension to current nanoparticle-based bioassays. PMID:23659350

Lactoferrin Adsorbed onto Biomimetic Hydroxyapatite Nanocrystals Controlling - In Vivo - the Helicobacter pylori Infection

PubMed Central

Fulgione, Andrea; Nocerino, Nunzia; Iannaccone, Marco; Roperto, Sante; Capuano, Federico; Roveri, Norberto; Lelli, Marco; Crasto, Antonio; Calogero, Armando; Pilloni, Argenia Paola; Capparelli, Rosanna

2016-01-01

Background The resistance of Helicobacter pylori to the antibiotic therapy poses the problem to discover new therapeutic approaches. Recently it has been stated that antibacterial, immunomodulatory, and antioxidant properties of lactoferrin are increased when this protein is surface-linked to biomimetic hydroxyapatite nanocrystals. Objective Based on these knowledge, the aim of the study was to investigate the efficacy of lactoferrin delivered by biomimetic hydroxyapatite nanoparticles with cell free supernatant from probiotic Lactobacillus paracasei as an alternative therapy against Helicobacter pylori infection. Methods Antibacterial and antinflammatory properties, humoral antibody induction, histopathological analysis and absence of side effects were evaluated in both in vitro and in vivo studies. Results The tests carried out have been demonstrated better performance of lactoferrin delivered by biomimetic hydroxyapatite nanoparticles combined with cell free supernatant from probiotic Lactobacillus paracasei compared to both lactoferrin and probiotic alone or pooled. Conclusion These findings indicate the effectiveness and safety of our proposed therapy as alternative treatment for Helicobacter pylori infection. PMID:27384186

Ultrasonic hyperactivation of cellulase immobilized on magnetic nanoparticles.

PubMed

Ladole, Mayur Ramrao; Mevada, Jayesh Sevantilal; Pandit, Aniruddha Bhalchandra

2017-09-01

In the present work, effect of low power, low frequency ultrasound on cellulase immobilized magnetic nanoparticles (cellulase@MNPs) was studied. To gain maximum activity recovery in cellulase@MNPs various parameters viz. ratio of MNPs:cellulase, concentration of glutaraldehyde and cross-linking time were optimized. The influence of ultrasonic power on cellulase@MNPs was studied. Under ultrasonic conditions at 24kHz, 6W power, and 6min of incubation time there was almost 3.6 fold increased in the catalytic activity of immobilized cellulase over the control. Results also indicated that there was improvement in pH and temperature stability of cellulase@MNPs. Furthermore, thermal deactivation energy required was more in cellulase@MNPs than that of the free cellulase. Secondary structural analysis revealed that there were conformational changes in free cellulase and cellulase@MNPs before and after sonication which might be responsible for enhanced activity after ultrasonication. Finally, the influence of ultrasound and cellulase@MNPs for biomass hydrolysis was studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantification of metallic nanoparticle morphology with tilt series imaging by transmission electron microscopy

NASA Astrophysics Data System (ADS)

Dutta, Aniruddha; Yuan, Biao; Clukay, Christopher J.; Grabill, Christopher N.; Heinrich, Helge; Bhattacharya, Aniket; Kuebler, Stephen M.

2012-02-01

We report on the quantitative analysis of electrolessly deposited Au and Ag nanoparticles (NPs) on SU8 polymer with the help of High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) in tilt series. Au NPs act as nucleating agents for the electroless deposition of silver. Au NPs were prepared by attachingAu^3+cations to amine functionalized SU8 polymeric surfaces and then reducing it with aqueous NaBH4. The nanoscale morphology of the deposited NPs on the surface of polymer has been studied from the dark field TEM cross sectional images. Ag NPs were deposited on the cross-linked polymeric surface from a silver citrate solution reduced by hydroquinone. HAADF-STEM enables us to determine the distances between the NPs and their exact locations at and near the surface. The particle distribution, sizes and densities provide us with the data necessary to control the parameters for the development of the electroless deposition technique for emerging nanoscale technologies.

Mussel-Inspired Protein Nanoparticles Containing Iron(III)-DOPA Complexes for pH-Responsive Drug Delivery.

PubMed

Kim, Bum Jin; Cheong, Hogyun; Hwang, Byeong Hee; Cha, Hyung Joon

2015-06-15

A novel bioinspired strategy for protein nanoparticle (NP) synthesis to achieve pH-responsive drug release exploits the pH-dependent changes in the coordination stoichiometry of iron(III)-3,4-dihydroxyphenylalanine (DOPA) complexes, which play a major cross-linking role in mussel byssal threads. Doxorubicin-loaded polymeric NPs that are based on Fe(III)-DOPA complexation were thus synthesized with a DOPA-modified recombinant mussel adhesive protein through a co-electrospraying process. The release of doxorubicin was found to be predominantly governed by a change in the structure of the Fe(III)-DOPA complexes induced by an acidic pH value. It was also demonstrated that the fabricated NPs exhibited effective cytotoxicity towards cancer cells through efficient cellular uptake and cytosolic release. Therefore, it is anticipated that Fe(III)-DOPA complexation can be successfully utilized as a new design principle for pH-responsive NPs for diverse controlled drug-delivery applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitive and Facile Electrochemiluminescent Immunoassay for Detecting Genetically Modified Rapeseed Based on Novel Carbon Nanoparticles.

PubMed

Gao, Hongfei; Wen, Luke; Wu, Yuhua; Yan, Xiaohong; Li, Jun; Li, Xiaofei; Fu, Zhifeng; Wu, Gang

2018-05-23

A highly sensitive electrochemiluminescent (ECL) immunoassay targeting PAT/ bar protein was facilely developed for genetically modified (GM) rapeseed detection using carbon nanoparticles (CNPs) originally prepared from printer toner. In this work, CNPs linked with antibody for PAT/ bar protein were used to modify a working electrode. After an immunoreaction between the PAT/ bar protein and its antibody, the immunocomplex formed on the electrode receptor region resulted in an inhibition of electron transfer between the electrode surface and the ECL substance, thus led to a decrease of ECL response. Under the optimal conditions, the ECL responses linearly decreased as the increase of the PAT/ bar protein concentration and the GM rapeseed RF3 content in the ranges of 0.10-10 ng/mL and 0.050-1.0%, with the limits of detection of 0.050 ng/mL and 0.020% (S/N = 3). These results open a facile, sensitive, and rapid approach for the safety control of agricultural GM rape.

Effect of solvent on the synthesis of SnO{sub 2} nanoparticles

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

Kumar, Virender; Singh, Karamjit; Singh, Kulwinder

Tin oxide (SnO{sub 2}) nanoparticles have been synthesized by co-precipitation method. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD) and Ultraviolet-Visible spectroscopy (UV-VIS). XRD analysis confirmed the formation of single phase of SnO{sub 2} nanoparticles. It has been found that solvents played important role in controlling the crystallite size of SnO{sub 2} nanoparticles. The XRD analysis showed well crystallized tetragonal SnO{sub 2} nanoparticles. The crystallite size of SnO{sub 2} nanoparticles varies with the solvent. Tauc plot showed that optical band gap was also tailored by controlling the solvent during synthesis.

Nanomedicine: nanoparticles, molecular biosensors, and targeted gene/drug delivery for combined single-cell diagnostics and therapeutics

NASA Astrophysics Data System (ADS)

Prow, Tarl W.; Salazar, Jose H.; Rose, William A.; Smith, Jacob N.; Reece, Lisa; Fontenot, Andrea A.; Wang, Nan A.; Lloyd, R. Stephen; Leary, James F.

2004-07-01

Next generation nanomedicine technologies are being developed to provide for continuous and linked molecular diagnostics and therapeutics. Research is being performed to develop "sentinel nanoparticles" which will seek out diseased (e.g. cancerous) cells, enter those living cells, and either perform repairs or induce those cells to die through apoptosis. These nanoparticles are envisioned as multifunctional "smart drug delivery systems". The nanosystems are being developed as multilayered nanoparticles (nanocrystals, nanocapsules) containing cell targeting molecules, intracellular re-targeting molecules, molecular biosensor molecules, and drugs/enzymes/gene therapy. These "nanomedicine systems" are being constructed to be autonomous, much like present-day vaccines, but will have sophisticated targeting, sensing, and feedback control systems-much more sophisticated than conventional antibody-based therapies. The fundamental concept of nanomedicine is to not to just kill all aberrant cells by surgery, radiation therapy, or chemotherapy. Rather it is to fix cells, when appropriate, one cell-at-a-time, to preserve and re-build organ systems. When cells should not be fixed, such as in cases where an improperly repaired cell might give rise to cancer cells, the nanomedical therapy would be to induce apoptosis in those cells to eliminate them without the damagin bystander effects of the inflammatory immune response system reacting to necrotic cells or those which have died from trauma or injury. The ultimate aim of nanomedicine is to combine diagnostics and therapeutics into "real-time medicine", using where possible in-vivo cytometry techniques for diagnostics and therapeutics. A number of individual components of these multi-component nanoparticles are already working in in-vitro and ex-vivo cell and tissue systems. Work has begun on construction of integrated nanomedical systems.

Measurement of Nanoparticles Release during Drilling of Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Gendre, L.; Marchante Rodriguez, V.; Abhyankar, H.; Blackburn, K.; Brighton, J. L.

2015-05-01

Nanomaterials are one of the promising technologies of this century. The Project on Emerging Nanotechnologies [1] reports more than 1600 consumer products based on nanotechnology that are currently on the market and advantages link to the reinforcement of polymeric materials using nano-fillers are not to demonstrate anymore. However, the concerns about safety and its consumer perception can slow down the acceptance of nanocomposites. Indeed, during its life-cycle, a nanotechnology-based product can release nano-sized particles exposing workers, consumers and environment and the risk involved in the use and disposal of such particles is not well known. The current legislation concerning chemicals and environment protection doesn't explicitly cover nanomaterials and changes undergone by nanoparticles during the products’ life cycle. Also, the possible physio-chemical changes that the nanoparticles may undergo during its life cycle are unknown. Industries need a standard method to evaluate nanoparticles release during products’ life cycle in order to improve the knowledge in nanomaterials risk assessment and the legislation, and to inform customers about the safety of nanomaterials and nanoproducts. This work aims to propose a replicable method in order to assess the release of nanoparticles during the machining of nanocomposites in a controlled environment. For this purpose, a new experimental set-up was implemented and issues observed in previous methods (background noise due to uncontrolled ambient environment and the process itself, unrepeatable machining parameters) were solved. A characterisation and validation of the chamber used is presented in this paper. Also, preliminary testing on drilling of polymer-based nanocomposites (Polyamide-6/Glass Fibre reinforced with nano-SiO2) manufactured by extrusion and injection moulding were achieved.

Ion transport controlled by nanoparticle-functionalized membranes.

PubMed

Barry, Edward; McBride, Sean P; Jaeger, Heinrich M; Lin, Xiao-Min

2014-12-17

From proton exchange membranes in fuel cells to ion channels in biological membranes, the well-specified control of ionic interactions in confined geometries profoundly influences the transport and selectivity of porous materials. Here we outline a versatile new approach to control a membrane's electrostatic interactions with ions by depositing ligand-coated nanoparticles around the pore entrances. Leveraging the flexibility and control by which ligated nanoparticles can be synthesized, we demonstrate how ligand terminal groups such as methyl, carboxyl and amine can be used to tune the membrane charge density and control ion transport. Further functionality, exploiting the ligands as binding sites, is demonstrated for sulfonate groups resulting in an enhancement of the membrane charge density. We then extend these results to smaller dimensions by systematically varying the underlying pore diameter. As a whole, these results outline a previously unexplored method for the nanoparticle functionalization of membranes using ligated nanoparticles to control ion transport.

Ion transport controlled by nanoparticle-functionalized membranes

NASA Astrophysics Data System (ADS)

Barry, Edward; McBride, Sean P.; Jaeger, Heinrich M.; Lin, Xiao-Min

2014-12-01

From proton exchange membranes in fuel cells to ion channels in biological membranes, the well-specified control of ionic interactions in confined geometries profoundly influences the transport and selectivity of porous materials. Here we outline a versatile new approach to control a membrane’s electrostatic interactions with ions by depositing ligand-coated nanoparticles around the pore entrances. Leveraging the flexibility and control by which ligated nanoparticles can be synthesized, we demonstrate how ligand terminal groups such as methyl, carboxyl and amine can be used to tune the membrane charge density and control ion transport. Further functionality, exploiting the ligands as binding sites, is demonstrated for sulfonate groups resulting in an enhancement of the membrane charge density. We then extend these results to smaller dimensions by systematically varying the underlying pore diameter. As a whole, these results outline a previously unexplored method for the nanoparticle functionalization of membranes using ligated nanoparticles to control ion transport.

The Sustainable Release of Vancomycin and Its Degradation Products From Nanostructured Collagen/Hydroxyapatite Composite Layers.

PubMed

Suchý, Tomáš; Šupová, Monika; Klapková, Eva; Horný, Lukáš; Rýglová, Šárka; Žaloudková, Margit; Braun, Martin; Sucharda, Zbyněk; Ballay, Rastislav; Veselý, Jan; Chlup, Hynek; Denk, František

2016-03-01

Infections of the musculoskeletal system present a serious problem with regard to the field of orthopedic and trauma medicine. The aim of the experiment described in this study was to develop a resorbable nanostructured composite layer with the controlled elution of antibiotics. The layer is composed of collagen, hydroxyapatite nanoparticles, and vancomycin hydrochloride (10 wt%). The stability of the collagen was enhanced by means of cross-linking. Four cross-linking agents were studied, namely an ethanol solution, a phosphate buffer solution of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide, genipin, and nordihydroguaiaretic acid. High performance liquid chromatography was used so as to characterize the in vitro release rates of the vancomycin and its crystalline degradation antibiotically inactive products over a 21-day period. The maximum concentration of the released active form of vancomycin (approximately 265 mg/L) exceeded the minimum inhibitory concentration up to an order of 17 times without triggering the burst releasing effect. At the end of the experiment, the minimum inhibitory concentration was exceeded by up to 6 times (approximately 100 mg/L). It was determined that the modification of collagen with hydroxyapatite nanoparticles does not negatively influence the sustainable release of vancomycin. The balance of vancomycin and its degradation products was observed after 14 days of incubation. Copyright © 2016. Published by Elsevier Inc.

Nano-antioxidants: An emerging strategy for intervention against neurodegenerative conditions.

PubMed

Sandhir, Rajat; Yadav, Aarti; Sunkaria, Aditya; Singhal, Nitin

2015-10-01

Oxidative stress has for long been linked to the neuronal cell death in many neurodegenerative conditions. Conventional antioxidant therapies have been less effective in preventing neuronal damage caused by oxidative stress due to their inability to cross the blood brain barrier. Nanoparticle antioxidants constitute a new wave of antioxidant therapies for prevention and treatment of diseases involving oxidative stress. It is believed that nanoparticle antioxidants have strong and persistent interactions with biomolecules and would be more effective against free radical induced damage. Nanoantioxidants include inorganic nanoparticles possessing intrinsic antioxidant properties, nanoparticles functionalized with antioxidants or antioxidant enzymes to function as an antioxidant delivery system. Nanoparticles containing antioxidants have shown promise as high-performance therapeutic nanomedicine in attenuating oxidative stress with potential applications in treating and preventing neurodegenerative conditions. However, to realize the full potential of nanoantioxidants, negative aspects associated with the use of nanoparticles need to be overcome to validate their long term applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Facile and high-efficient immobilization of histidine-tagged multimeric protein G on magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Lee, Jiho; Chang, Jeong Ho

2014-12-01

This work reports the high-efficient and one-step immobilization of multimeric protein G on magnetic nanoparticles. The histidine-tagged (His-tag) recombinant multimeric protein G was overexpressed in Escherichia coli BL21 by the repeated linking of protein G monomers with a flexible linker. High-efficient immobilization on magnetic nanoparticles was demonstrated by two different preparation methods through the amino-silane and chloro-silane functionalization on silica-coated magnetic nanoparticles. Three kinds of multimeric protein G such as His-tag monomer, dimer, and trimer were tested for immobilization efficiency. For these tests, bicinchoninic acid (BCA) assay was employed to determine the amount of immobilized His-tag multimeric protein G. The result showed that the immobilization efficiency of the His-tag multimeric protein G of the monomer, dimer, and trimer was increased with the use of chloro-silane-functionalized magnetic nanoparticles in the range of 98% to 99%, rather than the use of amino-silane-functionalized magnetic nanoparticles in the range of 55% to 77%, respectively.

Collagen-Gold Nanoparticle Conjugates for Versatile Biosensing

PubMed Central

Unser, Sarah; Holcomb, Samuel; Cary, ReJeana; Sagle, Laura

2017-01-01

Integration of noble metal nanoparticles with proteins offers promising potential to create a wide variety of biosensors that possess both improved selectivity and versatility. The multitude of functionalities that proteins offer coupled with the unique optical properties of noble metal nanoparticles can allow for the realization of simple, colorimetric sensors for a significantly larger range of targets. Herein, we integrate the structural protein collagen with 10 nm gold nanoparticles to develop a protein-nanoparticle conjugate which possess the functionality of the protein with the desired colorimetric properties of the nanoparticles. Applying the many interactions that collagen undergoes in the extracellular matrix, we are able to selectively detect both glucose and heparin with the same collagen-nanoparticle conjugate. Glucose is directly detected through the cross-linking of the collagen fibrils, which brings the attached nanoparticles into closer proximity, leading to a red-shift in the LSPR frequency. Conversely, heparin is detected through a competition assay in which heparin-gold nanoparticles are added to solution and compete with heparin in the solution for the binding sites on the collagen fibrils. The collagen-nanoparticle conjugates are shown to detect both glucose and heparin in the physiological range. Lastly, glucose is selectively detected in 50% mouse serum with the collagen-nanoparticle devices possessing a linear range of 3–25 mM, which is also within the physiologically relevant range. PMID:28212282

Transport of bare and capped zinc oxide nanoparticles is dependent on porous medium composition

NASA Astrophysics Data System (ADS)

Kurlanda-Witek, H.; Ngwenya, B. T.; Butler, I. B.

2014-07-01

Zinc oxide (ZnO) nanoparticles are one of the most frequently used nanoparticles in industry and hence are likely to be introduced to the groundwater environment. The mobility of these nanoparticles in different aquifer materials has not been assessed. While some studies have been published on the transport of ZnO nanoparticles in individual porous media, these studies do not generally account for varying porous medium composition both within and between aquifers. As a first step towards understanding the impact of this variability, this paper compares the transport of bare ZnO nanoparticles (bZnO-NPs) and capped ZnO nanoparticles, coated with tri-aminopropyltriethoxysilane (cZnO-NPs), in saturated columns packed with glass beads, fine grained sand and fine grained calcite, at near-neutral pH and groundwater salinity levels. With the exception of cZnO-NPs in sand columns, ZnO nanoparticles are highly immobile in all three types of studied porous media, with most retention taking place near the column inlet. Results are in general agreement with DLVO theory, and the deviation in experiments with cZnO-NPs flowing through columns packed with sand is linked to variability in zeta potential of the capped nanoparticles and sand grains. Therefore, differences in surface charge of nanoparticles and porous media are demonstrated to be key drivers in nanoparticle transport.

Incorporation of nanoparticles into polymersomes: size and concentration effects.

PubMed

Jaskiewicz, Karmena; Larsen, Antje; Schaeffel, David; Koynov, Kaloian; Lieberwirth, Ingo; Fytas, George; Landfester, Katharina; Kroeger, Anja

2012-08-28

Because of the rapidly growing field of nanoparticles in therapeutic applications, understanding and controlling the interaction between nanoparticles and membranes is of great importance. While a membrane is exposed to nanoparticles its behavior is mediated by both their biological and physical properties. Constant interplay of these biological and physicochemical factors makes selective studies of nanoparticles uptake demanding. Artificial model membranes can serve as a platform to investigate physical parameters of the process in the absence of any biofunctional molecules and/or supplementary energy. Here we report on photon- and fluorescence-correlation spectroscopic studies of the uptake of nanosized SiO(2) nanoparticles by poly(dimethylsiloxane)-block-poly(2-methyloxazoline) vesicles allowing species selectivity. Analogous to the cell membrane, polymeric membrane incorporates particles using membrane fission and particles wrapping as suggested by cryo-TEM imaging. It is revealed that the incorporation process can be controlled to a significant extent by changing nanoparticles size and concentration. Conditions for nanoparticle uptake and controlled filling of polymersomes are presented.

Generation of Well-Defined Micro/Nanoparticles via Advanced Manufacturing Techniques for Therapeutic Delivery

PubMed Central

Zhang, Peipei; Xia, Junfei; Luo, Sida

2018-01-01

Micro/nanoparticles have great potentials in biomedical applications, especially for drug delivery. Existing studies identified that major micro/nanoparticle features including size, shape, surface property and component materials play vital roles in their in vitro and in vivo applications. However, a demanding challenge is that most conventional particle synthesis techniques such as emulsion can only generate micro/nanoparticles with a very limited number of shapes (i.e., spherical or rod shapes) and have very loose control in terms of particle sizes. We reviewed the advanced manufacturing techniques for producing micro/nanoparticles with precisely defined characteristics, emphasizing the use of these well-controlled micro/nanoparticles for drug delivery applications. Additionally, to illustrate the vital roles of particle features in therapeutic delivery, we also discussed how the above-mentioned micro/nanoparticle features impact in vitro and in vivo applications. Through this review, we highlighted the unique opportunities in generating controllable particles via advanced manufacturing techniques and the great potential of using these micro/nanoparticles for therapeutic delivery. PMID:29670013

Silica passivated conjugated polymer nanoparticles for biological imaging applications

NASA Astrophysics Data System (ADS)

Bourke, Struan; Urbano, Laura; Olona, Antoni; Valderrama, Ferran; Dailey, Lea Ann; Green, Mark A.

2017-02-01

Colorectal and prostate cancers are major causes of cancer-related death, with early detection key to increased survival. However, as symptoms occur during advanced stages and current diagnostic methods have limitations, there is a need for new fluorescent probes that remain bright, are biocompatible and can be targeted. Conjugated polymer nanoparticles have shown great promise in biological imaging due to their unique optical properties. We have synthesised small, bright, photo-stable CN-PPV, nanoparticles encapsulated with poloxamer polymer and a thin silica shell. By incubating the CN-PPV silica shelled cross-linked (SSCL) nanoparticles in mammalian (HeLa) cells; we were able to show that cellular uptake occurred. Uptake was also shown by incubating the nanoparticles in RWPE-1, WPE1-NB26 and WPE1- NA22 prostate cancer cell lines. Finally, HEK cells were used to show the particles had limited cytotoxicity.

Protein bio-corona: critical issue in immune nanotoxicology.

PubMed

Neagu, Monica; Piperigkou, Zoi; Karamanou, Konstantina; Engin, Ayse Basak; Docea, Anca Oana; Constantin, Carolina; Negrei, Carolina; Nikitovic, Dragana; Tsatsakis, Aristidis

2017-03-01

With the expansion of the nanomedicine field, the knowledge focusing on the behavior of nanoparticles in the biological milieu has rapidly escalated. Upon introduction to a complex biological system, nanomaterials dynamically interact with all the encountered biomolecules and form the protein "bio-corona." The decoration with these surface biomolecules endows nanoparticles with new properties. The present review will address updates of the protein bio-corona characteristics as influenced by nanoparticle's physicochemical properties and by the particularities of the encountered biological milieu. Undeniably, bio-corona generation influences the efficacy of the nanodrug and guides the actions of innate and adaptive immunity. Exploiting the dynamic process of protein bio-corona development in combination with the new engineered horizons of drugs linked to nanoparticles could lead to innovative functional nanotherapies. Therefore, bio-medical nanotechnologies should focus on the interactions of nanoparticles with the immune system for both safety and efficacy reasons.

Stability limits and defect dynamics in Ag nanoparticles probed by Bragg coherent diffractive imaging

DOE PAGES

Liu, Y.; Lopes, P. P.; Cha, W.; ...

2017-02-10

Dissolution is critical to nanomaterial stability, especially for partially dealloyed nanoparticle catalysts. Unfortunately, highly active catalysts are often not stable in their reactive environments, preventing widespread application. Thus, focusing on the structure–stability relationship at the nanoscale is crucial and will likely play an important role in meeting grand challenges. Recent advances in imaging capability have come from electron, X-ray, and other techniques but tend to be limited to specific sample environments and/or two-dimensional images. Here, we report investigations into the defect-stability relationship of silver nanoparticles to voltage-induced electrochemical dissolution imaged in situ in three dimensional detail by Bragg coherent diffractivemore » imaging. We first determine the average dissolution kinetics by stationary probe rotating disk electrode in combination with inductively coupled plasma mass spectrometry, which allows in situ measurement of Ag+ ion formation. We then observe the dissolution and redeposition processes in single nanocrystals, providing unique insight about the role of surface strain, defects, and their coupling to the dissolution chemistry. Finally, the methods developed and the knowledge gained go well beyond a “simple” silver electrochemistry and are applicable to all electrocatalytic reactions where functional links between activity and stability are controlled by structure and defect dynamics.« less

Stability limits and defect dynamics in Ag nanoparticles probed by Bragg coherent diffractive imaging

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

Liu, Y.; Lopes, P. P.; Cha, W.

Dissolution is critical to nanomaterial stability, especially for partially dealloyed nanoparticle catalysts. Unfortunately, highly active catalysts are often not stable in their reactive environments, preventing widespread application. Thus, focusing on the structure–stability relationship at the nanoscale is crucial and will likely play an important role in meeting grand challenges. Recent advances in imaging capability have come from electron, X-ray, and other techniques but tend to be limited to specific sample environments and/or two-dimensional images. Here, we report investigations into the defect-stability relationship of silver nanoparticles to voltage-induced electrochemical dissolution imaged in situ in three dimensional detail by Bragg coherent diffractivemore » imaging. We first determine the average dissolution kinetics by stationary probe rotating disk electrode in combination with inductively coupled plasma mass spectrometry, which allows in situ measurement of Ag+ ion formation. We then observe the dissolution and redeposition processes in single nanocrystals, providing unique insight about the role of surface strain, defects, and their coupling to the dissolution chemistry. Finally, the methods developed and the knowledge gained go well beyond a “simple” silver electrochemistry and are applicable to all electrocatalytic reactions where functional links between activity and stability are controlled by structure and defect dynamics.« less

Biosynthesis of size-controlled gold nanoparticles using fungus, Penicillium sp.

PubMed

Zhang, Xiaorong; He, Xiaoxiao; Wang, Kemin; Wang, Yonghong; Li, Huimin; Tan, Weihong

2009-10-01

The unique optoelectronic and physicochemical properties of gold nanoparticles are significantly dependent on the particle size, shape and structure. In this paper, biosynthesis of size-controlled gold nanoparticles using fungus Penicillium sp. is reported. Fungus Penicillium sp. could successfully bioreduce and nucleate AuCl4(-) ions, and lead to the assembly and formation of intracellular Au nanoparticles with spherical morphology and good monodispersity after exposure to HAuCl4 solution. Reaction temperature, as an important physiological parameter for fungus Penicillium sp. growth, could significantly control the size of the biosynthesized Au nanoparticles. The biological compositions and FTIR spectra analysis of fungus Penicillium sp. exposed to HAuCl4 solution indicated the intracellular reducing sugar played an important role in the occurrence of intracellular reduction of AuCl4(-) ions and the growth of gold nanoparticles. Furthermore, the intracellular gold nanoparticles could be easily separated from the fungal cell lysate by ultrasonication and centrifugation.

Fabrication and evaluation of SDF-1 loaded galactosylated chitosan nanoparticles for liver targeting

NASA Astrophysics Data System (ADS)

Xue-Hui, Chu; Zhang-Qi, Feng; Qian, Xu; Jiang-Qiang, Xiao; Xian-Wen, Yuan; Xi-Tai, Sun

2017-03-01

Objective. SDF-1 loaded galactosylated chitosan (GC) nanoparticles for liver targeting were synthesized by electrospraying technique, and its biocompatibility and liver targeting effect were evaluated. Method. The SDF-1 loaded GC nanoparticles were constructed and its morphology was observed by the scanning electron microscopy (SEM). Hepatocytes were harvested and cocultured with the nanoparticles, and the albumin secretion and urea synthesis were detected by enzyme-linked immunosorbent assay assay, the concentration of lactate dehydrogenase (LDH) and tumor necrosis factor-α (TNF-α) was also measured. Finally, the nanoparticles were injected intravenously through the caudal vein of rat, and its liver targeting effect was evaluated. Result. SEM showed the nanoparticles distributed uniformly, with an average diameter of 100 nm and a regular spherical shape. There was no significant difference in urea synthesis, albumin secretion, concentration of LDH and TNF-α between two groups (p > 0.05). The nanoparticles were significantly accumulated in the liver tissue after its injection, but seldom fluorescence signals were observed in the lung, spleen, heart and kidney. Conclusion. The SDF-1 loaded GC nanoparticles showed uniform distribution, good biocompatibility and liver targeting effect, and suggested its potential application as a liver targeting delivery system.

Ion mediated targeting of cells with nanoparticles

NASA Astrophysics Data System (ADS)

Maheshwari, Vivek; Fu, Jinlong

2010-03-01

In eukaryotic cells, Ca^2+ ions are necessary for intracellular signaling, in activity of mitochondria and a variety of other cellular process that have been linked to cell apoptosis, proteins synthesis and cell-cycle regulation. Here we show that Ca^2+ ions, serving as the bio-compatible interface can be used to target Saccharomyces cerevisiae (SaC, baker's yeast), a model eukaryotic cell, with Au nanoparticles (10 nm). The Ca^2+ ions bind to the carboxylic acid groups in the citrate functionalized Au nanoparticles. This transforms the nanoparticles into micron long 1-D branched chain assemblies due to inter-particle dipole-dipole interaction and inter-particle bonding due to the divalent nature of the Ca^2+ ion. A similar transformation is observed with the use of divalent ions Mg^2+, Cd^2+ and Fe^2+. The 1-D assembly aids the interfacing of ion-nanoparticles on the cell by providing multiple contact points. Further monovalent ions such as Na^+ are also effective for the targeting of the cell with nanoparticles. However Na-Au nanoparticles are limited in their deposition as they exist in solution as single particles. The cells remain alive after the deposition process and their vitality is unaffected by the interfacing with ion-nanoparticles.

Protamine-based nanoparticles as new antigen delivery systems.

PubMed

González-Aramundiz, José Vicente; Peleteiro Olmedo, Mercedes; González-Fernández, África; Alonso Fernández, María José; Csaba, Noemi Stefánia

2015-11-01

The use of biodegradable nanoparticles as antigen delivery vehicles is an attractive approach to overcome the problems associated with the use of Alum-based classical adjuvants. Herein we report, the design and development of protamine-based nanoparticles as novel antigen delivery systems, using recombinant hepatitis B surface antigen as a model viral antigen. The nanoparticles, composed of protamine and a polysaccharide (hyaluronic acid or alginate), were obtained using a mild ionic cross-linking technique. The size and surface charge of the nanoparticles could be modulated by adjusting the ratio of the components. Prototypes with optimal physicochemical characteristics and satisfactory colloidal stability were selected for the assessment of their antigen loading capacity, antigen stability during storage and in vitro and in vivo proof-of-concept studies. In vitro studies showed that antigen-loaded nanoparticles induced the secretion of cytokines by macrophages more efficiently than the antigen in solution, thus indicating a potential adjuvant effect of the nanoparticles. Finally, in vivo studies showed the capacity of these systems to trigger efficient immune responses against the hepatitis B antigen following intramuscular administration, suggesting the potential interest of protamine-polysaccharide nanoparticles as antigen delivery systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Sugar-Terminated Nanoparticle Chaperones Are 102-105 Times Better Than Molecular Sugars in Inhibiting Protein Aggregation and Reducing Amyloidogenic Cytotoxicity.

PubMed

Pradhan, Nibedita; Shekhar, Shashi; Jana, Nihar R; Jana, Nikhil R

2017-03-29

Sugar-based osmolyte molecules are known to stabilize proteins under stress, but usually they have poor chaperone performance in inhibiting protein aggregation. Here, we show that the nanoparticle form of sugars molecule can enhance their chaperone performance typically by 10 2 -10 5 times, compared to molecular sugar. Sugar-based plate-like nanoparticles of 20-40 nm hydrodynamic size have been synthesized by simple heating of acidic aqueous solution of glucose/sucrose/maltose/trehalose. These nanoparticles have excitation-dependent green/yellow/orange emission and surface chemistry identical to the respective sugar molecule. Fibrillation of lysozyme/insulin/amyloid beta in extracellular space, aggregation of mutant huntingtin protein inside model neuronal cell, and cytotoxic effect of fibrils are investigated in the presence of these sugar nanoparticles. We found that sugar nanoparticles are 10 2 -10 5 times efficient than respective sugar molecules in inhibiting protein fibrillation and preventing cytotoxicity arising of fibrils. We propose that better performance of the nanoparticle form is linked to its stronger binding with fibril structure and enhanced cell uptake. This result suggests that nanoparticle form of osmolyte can be an attractive option in prevention and curing of protein aggregation-derived diseases.

Detection of single-nucleotide polymorphisms using gold nanoparticles and single-strand-specific nucleases.

PubMed

Chen, Yen-Ting; Hsu, Chiao-Ling; Hou, Shao-Yi

2008-04-15

The current study reports an assay approach that can detect single-nucleotide polymorphisms (SNPs) and identify the position of the point mutation through a single-strand-specific nuclease reaction and a gold nanoparticle assembly. The assay can be implemented via three steps: a single-strand-specific nuclease reaction that allows the enzyme to truncate the mutant DNA; a purification step that uses capture probe-gold nanoparticles and centrifugation; and a hybridization reaction that induces detector probe-gold nanoparticles, capture probe-gold nanoparticles, and the target DNA to form large DNA-linked three-dimensional aggregates of gold nanoparticles. At high temperature (63 degrees C in the current case), the purple color of the perfect match solution would not change to red, whereas a mismatched solution becomes red as the assembled gold nanoparticles separate. Using melting analysis, the position of the point mutation could be identified. This assay provides a convenient colorimetric detection that enables point mutation identification without the need for expensive mass spectrometry. To our knowledge, this is the first report concerning SNP detection based on a single-strand-specific nuclease reaction and a gold nanoparticle assembly.

Photoresponsive lipid-polymer hybrid nanoparticles for controlled doxorubicin release

NASA Astrophysics Data System (ADS)

Yao, Cuiping; Wu, Ming; Zhang, Cecheng; Lin, Xinyi; Wei, Zuwu; Zheng, Youshi; Zhang, Da; Zhang, Zhenxi; Liu, Xiaolong

2017-06-01

Currently, photoresponsive nanomaterials are particularly attractive due to their spatial and temporal controlled drug release abilities. In this work, we report a photoresponsive lipid-polymer hybrid nanoparticle for remote controlled delivery of anticancer drugs. This hybrid nanoparticle comprises three distinct functional components: (i) a poly(D,L-lactide-co-glycolide) (PLGA) core to encapsulate doxorubicin; (ii) a soybean lecithin monolayer at the interface of the core and shell to act as a molecular fence to prevent drug leakage; (iii) a photoresponsive polymeric shell with anti-biofouling properties to enhance nanoparticle stability, which could be detached from the nanoparticle to trigger the drug release via a decrease in the nanoparticle’s stability under light irradiation. In vitro results revealed that this core-shell nanoparticle had excellent light-controlled drug release behavior (76% release with light irradiation versus 10% release without light irradiation). The confocal microscopy and flow cytometry results also further demonstrated the light-controlled drug release behavior inside the cancer cells. Furthermore, a CCK8 assay demonstrated that light irradiation could significantly improve the efficiency of killing cancer cells. Meanwhile, whole-animal fluorescence imaging of a tumor-bearing mouse also confirmed that light irradiation could trigger drug release in vivo. Taken together, our data suggested that a hybrid nanoparticle could be a novel light controlled drug delivery system for cancer therapy.

Controlling Non-Equilibrium Structure Formation on the Nanoscale.

PubMed

Buchmann, Benedikt; Hecht, Fabian Manfred; Pernpeintner, Carla; Lohmueller, Theobald; Bausch, Andreas R

2017-12-06

Controlling the structure formation of gold nanoparticle aggregates is a promising approach towards novel applications in many fields, ranging from (bio)sensing to (bio)imaging to medical diagnostics and therapeutics. To steer structure formation, the DNA-DNA interactions of DNA strands that are coated on the surface of the particles have become a valuable tool to achieve precise control over the interparticle potentials. In equilibrium approaches, this technique is commonly used to study particle crystallization and ligand binding. However, regulating the structural growth processes from the nano- to the micro- and mesoscale remains elusive. Here, we show that the non-equilibrium structure formation of gold nanoparticles can be stirred in a binary heterocoagulation process to generate nanoparticle clusters of different sizes. The gold nanoparticles are coated with sticky single stranded DNA and mixed at different stoichiometries and sizes. This not only allows for structural control but also yields access to the optical properties of the nanoparticle suspensions. As a result, we were able to reliably control the kinetic structure formation process to produce cluster sizes between tens of nanometers up to micrometers. Consequently, the intricate optical properties of the gold nanoparticles could be utilized to control the maximum of the nanoparticle suspension extinction spectra between 525 nm and 600 nm. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of Complementary DNA and Salt on the Thermoresponsiveness of Poly(N-isopropylacrylamide)-b-DNA.

PubMed

Fujita, Masahiro; Hiramine, Hayato; Pan, Pengju; Hikima, Takaaki; Maeda, Mizuo

2016-02-02

The thermoresponsive structural transition of poly(N-isopropylacrylamide) (PNIPAAm)-b-DNA copolymers was explored. Molecular assembly of the block copolymers was facilitated by adding salt, and this assembly was not nucleated by the association between DNA strands but by the coil-globule transition of PNIPAAm blocks. Below the lower critical solution temperature (LCST) of PNIPAAm, the copolymer solution remained transparent even at high salt concentrations, regardless of whether DNA was hybridized with its complementary partner to form a double-strand (or single-strand) structure. At the LCST, the hybridized copolymer assembled in spherical nanoparticles, surrounded by double-stranded DNA; subsequently, the non-cross-linking aggregation occurred, while the nanoparticles were dispersed if the salt concentration was low or DNA blocks were unhybridized. When the DNA duplex was denatured to a single-stranded state by heating, the aggregated nanoparticles redispersed owing to the recovery of the steric repulsion of the DNA strands. The changes in the steric and electrostatic effects by hybridization and the addition of salt did not result in any specific attraction between DNA strands but merely decreased the repulsive interactions. The van der Waals attraction between the nanoparticles overcame such repulsive interactions so that the non-cross-linking aggregation of the micellar particles was mediated.

Athero-inflammatory nanotherapeutics: Ferulic acid-based poly(anhydride-ester) nanoparticles attenuate foam cell formation by regulating macrophage lipogenesis and reactive oxygen species generation.

PubMed

Chmielowski, Rebecca A; Abdelhamid, Dalia S; Faig, Jonathan J; Petersen, Latrisha K; Gardner, Carol R; Uhrich, Kathryn E; Joseph, Laurie B; Moghe, Prabhas V

2017-07-15

Enhanced bioactive anti-oxidant formulations are critical for treatment of inflammatory diseases, such as atherosclerosis. A hallmark of early atherosclerosis is the uptake of oxidized low density lipoprotein (oxLDL) by macrophages, which results in foam cell and plaque formation in the arterial wall. The hypolipidemic, anti-inflammatory, and antioxidative properties of polyphenol compounds make them attractive targets for treatment of atherosclerosis. However, high concentrations of antioxidants can reverse their anti-atheroprotective properties and cause oxidative stress within the artery. Here, we designed a new class of nanoparticles with anti-oxidant polymer cores and shells comprised of scavenger receptor targeting amphiphilic macromolecules (AMs). Specifically, we designed ferulic acid-based poly(anhydride-ester) nanoparticles to counteract the uptake of high levels of oxLDL and regulate reactive oxygen species generation (ROS) in human monocyte derived macrophages (HMDMs). Compared to all compositions examined, nanoparticles with core ferulic acid-based polymers linked by diglycolic acid (PFAG) showed the greatest inhibition of oxLDL uptake. At high oxLDL concentrations, the ferulic acid diacids and polymer nanoparticles displayed similar oxLDL uptake. Treatment with the PFAG nanoparticles downregulated the expression of macrophage scavenger receptors, CD-36, MSR-1, and LOX-1 by about 20-50%, one of the causal factors for the decrease in oxLDL uptake. The PFAG nanoparticle lowered ROS production by HMDMs, which is important for maintaining macrophage growth and prevention of apoptosis. Based on these results, we propose that ferulic acid-based poly(anhydride ester) nanoparticles may offer an integrative strategy for the localized passivation of the early stages of the atheroinflammatory cascade in cardiovascular disease. Future development of anti-oxidant formulations for atherosclerosis applications is essential to deliver an efficacious dose while limiting localized concentrations of pro-oxidants. In this study, we illustrate the potential of degradable ferulic acid-based polymer nanoparticles to control macrophage foam cell formation by significantly reducing oxLDL uptake through downregulation of scavenger receptors, CD-36, MSR-1, and LOX-1. Another critical finding is the ability of the degradable ferulate-based polymer nanoparticles to lower macrophage reactive oxygen species (ROS) levels, a precursor to apoptosis and plaque escalation. The degradable ferulic acid-based polymer nanoparticles hold significant promise as a means to alter the treatment and progression of atherosclerosis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Magnetic field activated lipid-polymer hybrid nanoparticles for stimuli-responsive drug release.

PubMed

Kong, Seong Deok; Sartor, Marta; Hu, Che-Ming Jack; Zhang, Weizhou; Zhang, Liangfang; Jin, Sungho

2013-03-01

Stimuli-responsive nanoparticles (SRNPs) offer the potential of enhancing the therapeutic efficacy and minimizing the side-effects of chemotherapeutics by controllably releasing the encapsulated drug at the target site. Currently controlled drug release through external activation remains a major challenge during the delivery of therapeutic agents. Here we report a lipid-polymer hybrid nanoparticle system containing magnetic beads for stimuli-responsive drug release using a remote radio frequency (RF) magnetic field. These hybrid nanoparticles show long-term stability in terms of particle size and polydispersity index in phosphate-buffered saline (PBS). Controllable loading of camptothecin (CPT) and Fe(3)O(4) in the hybrid nanoparticles was demonstrated. RF-controlled drug release from these nanoparticles was observed. In addition, cellular uptake of the SRNPs into MT2 mouse breast cancer cells was examined. Using CPT as a model anticancer drug the nanoparticles showed a significant reduction in MT2 mouse breast cancer cell growth in vitro in the presence of a remote RF field. The ease of preparation, stability, and controllable drug release are the strengths of the platform and provide the opportunity to improve cancer chemotherapy. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of a dose-controlled multiculture cell exposure chamber for efficient delivery of airborne and engineered nanoparticles

NASA Astrophysics Data System (ADS)

Asimakopoulou, Akrivi; Daskalos, Emmanouil; Lewinski, Nastassja; Riediker, Michael; Papaioannou, Eleni; Konstandopoulos, Athanasios G.

2013-04-01

In order to study the various health influencing parameters related to engineered nanoparticles as well as to soot emitted by Diesel engines, there is an urgent need for appropriate sampling devices and methods for cell exposure studies that simulate the respiratory system and facilitate associated biological and toxicological tests. The objective of the present work was the further advancement of a Multiculture Exposure Chamber (MEC) into a dose-controlled system for efficient delivery of nanoparticles to cells. It was validated with various types of nanoparticles (Diesel engine soot aggregates, engineered nanoparticles for various applications) and with state-of-the-art nanoparticle measurement instrumentation to assess the local deposition of nanoparticles on the cell cultures. The dose of nanoparticles to which cell cultures are being exposed was evaluated in the normal operation of the in vitro cell culture exposure chamber based on measurements of the size specific nanoparticle collection efficiency of a cell free device. The average efficiency in delivering nanoparticles in the MEC was approximately 82%. The nanoparticle deposition was demonstrated by Transmission Electron Microscopy (TEM). Analysis and design of the MEC employs Computational Fluid Dynamics (CFD) and true to geometry representations of nanoparticles with the aim to assess the uniformity of nanoparticle deposition among the culture wells. Final testing of the dose-controlled cell exposure system was performed by exposing A549 lung cell cultures to fluorescently labeled nanoparticles. Delivery of aerosolized nanoparticles was demonstrated by visualization of the nanoparticle fluorescence in the cell cultures following exposure. Also monitored was the potential of the aerosolized nanoparticles to generate reactive oxygen species (ROS) (e.g. free radicals and peroxides generation), thus expressing the oxidative stress of the cells which can cause extensive cellular damage or damage on DNA.

Strategies for the synthesis of supported gold palladium nanoparticles with controlled morphology and composition.

PubMed

Hutchings, Graham J; Kiely, Christopher J

2013-08-20

The discovery that supported gold nanoparticles are exceptionally effective catalysts for redox reactions has led to an explosion of interest in gold nanoparticles. In addition, incorporating a second metal as an alloy with gold can enhance the catalyst performance even more. The addition of small amounts of gold to palladium, in particular, and vice versa significantly enhances the activity of supported gold-palladium nanoparticles as redox catalysts through what researchers believe is an electronic effect. In this Account, we describe and discuss methodologies for the synthesis of supported gold-palladium nanoparticles and their use as heterogeneous catalysts. In general, three key challenges need to be addressed in the synthesis of bimetallic nanoparticles: (i) control of the particle morphology, (ii) control of the particle size distribution, and (iii) control of the nanoparticle composition. We describe three methodologies to address these challenges. First, we discuss the relatively simple method of coimpregnation. Impregnation allows control of particle morphology during alloy formation but does not control the particle compositions or the particle size distribution. Even so, we contend that this method is the best preparation method in the catalyst discovery phase of any project, since it permits the investigation of many different catalyst structures in one experiment, which may aid the identification of new catalysts. A second approach, sol-immobilization, allows enhanced control of the particle size distribution and the particle morphology, but control of the composition of individual nanoparticles is not possible. Finally, a modified impregnation method can allow the control of all three of these crucial parameters. We discuss the effect of the different methodologies on three redox reactions: benzyl alcohol oxidation, toluene oxidation, and the direct synthesis of hydrogen peroxide. We show that the coimpregnation method provides the best reaction selectivity for benzyl alcohol oxidation and the direct synthesis of hydrogen peroxide. However, because of the reaction mechanism, the sol-immobilzation method gives very active and selective catalysts for toluene oxidation. We discuss the possible nature of the preferred active structures of the supported nanoparticles for these reactions. This paper is based on the IACS Heinz Heinemann Award Lecture entitled "Catalysis using gold nanoparticles" which was given in Munich in July 2012.

Antibacterial cotton fabric with enhanced durability prepared using silver nanoparticles and carboxymethyl chitosan.

PubMed

Xu, QingBo; Xie, LiJing; Diao, Helena; Li, Fang; Zhang, YanYan; Fu, FeiYa; Liu, XiangDong

2017-12-01

Carboxymethyl chitosan (CMCTS) and silver nanoparticles (Ag NPs) were successfully linked onto a cotton fabric surface through a simple mist modification process. The CMCTS binder was covalently linked to the cotton fabric via esterification and the Ag NPs were tightly adhered to the fiber surface by coordination bonds with the amine groups of CMCTS. As a result, the coating of Ag NPs on the cotton fabric showed excellent antibacterial properties and laundering durability. After 50 consecutive laundering cycles, the bacterial reduction rates (BR) against both S. aureus and E. coli remained over 95%. It has potential applications in a wide variety of fields such as sportswear, socks, and medical textile. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hierarchically assembled theranostic nanostructures for siRNA delivery and imaging applications.

PubMed

Shrestha, Ritu; Elsabahy, Mahmoud; Luehmann, Hannah; Samarajeewa, Sandani; Florez-Malaver, Stephanie; Lee, Nam S; Welch, Michael J; Liu, Yongjian; Wooley, Karen L

2012-10-24

Dual functional hierarchically assembled nanostructures, with two unique functions of carrying therapeutic cargo electrostatically and maintaining radiolabeled imaging agents covalently within separate component building blocks, have been developed via the supramolecular assembly of several spherical cationic shell cross-linked nanoparticles clustered around a central anionic shell cross-linked cylinder. The shells of the cationic nanoparticles and the hydrophobic core domain of the anionic central cylindrical nanostructure of the assemblies were utilized to complex negatively charged nucleic acids (siRNA) and to undergo radiolabeling, respectively, for potential theranostic applications. The assemblies exhibited exceptional cell transfection and radiolabeling efficiencies, providing an overall advantage over the individual components, which could each facilitate only one or the other of the functions.

Bioconjugation of neutral protease on silk fibroin nanoparticles and application in the controllable hydrolysis of sericin.

PubMed

Zhu, Lin; Hu, Ren-Ping; Wang, Hai-Yan; Wang, Yuan-Jing; Zhang, Yu-Qing

2011-09-28

Bombyx mori silk fibroin is a protein-based macromolecular biopolymer with remarkable biocompatibility. Silk fiber was degummed and subjected to a series of treatments, including dissolution and dialysis, to yield an aqueous solution of silk fibroin, which was introduced rapidly into excess acetone to produce crystalline silk fibroin nanoparticles (SFNs). The SFNs were conjugated covalently with a neutral protease (NP) using glutaraldehyde as the cross-linking reagent. The objective of this study was to determine the optimal conditions for biosynthesis of the SFN-NP bioconjugates. First, SFN-NP was obtained by covalent cross-linking of SFN and NP at an SFN/NP ratio of 5-8 mg:1 IU with 0.75% glutaraldehyde for 6 h at 25 °C. When adding 50 IU of the enzyme, the residual activity of biological conjugates was increased to 31.45%. Studies on the enzyme activity of SFN-NP and its kinetics showed that the stability of SFN-NP bioconjugates was greater than that of the free enzyme, the optimum reactive temperature range was increased by 5-10 °C, and the optimum pH value range was increased to 6.5-8.0. Furthermore, the thermal stability was improved to some extent. A controlled hydrolysis test using the poorly water-soluble protein sericin as a substrate and SFN-NP as the enzyme showed that the longer the reaction time (within 1 h), the smaller the molecular mass (<30 kDa) is of the sericin peptide produced. The SFN-NP bioconjugate is easily recovered by centrifugation and can be used repeatedly. The highly efficient processing technology and the use of SFN as a novel vector for a protease has great potential for research and the development of food processing.

Platinum covalent shell cross-linked micelles designed to deliver doxorubicin for synergistic combination cancer therapy

PubMed Central

Zhu, Caiying; Xiao, Jingjing; Tang, Ming; Feng, Hua; Chen, Wulian; Du, Ming

2017-01-01

The preparation of polymer therapeutics capable of controlled release of multiple chemotherapeutic drugs has remained a tough problem in synergistic combination cancer therapy. Herein, a novel dual-drug co-delivery system carrying doxorubicin (DOX) and platinum(IV) (Pt[IV]) was developed. An amphiphilic diblock copolymer, PCL-b-P(OEGMA-co-AzPMA), was synthesized and used as a nanoscale drug carrier in which DOX and Pt(IV) could be packaged together. The copolymers were shell cross-linked by Pt(IV) prodrug via a click reaction. Studies on the in vitro drug release and cellular uptake of the dual-drug co-delivery system showed that the micelles were effectively taken up by the cells and simultaneously released drugs in the cells. Futhermore, the co-delivery polymer nanoparticles caused much higher cell death in HeLa and A357 tumor cells than either the free drugs or single-drug-loaded micelles at the same dosage, exhibiting a synergistic combination of DOX and Pt(IV). The results obtained with the shell cross-linked micelles based on an anticancer drug used as a cross-linking linkage suggested a promising application of the micelles for multidrug delivery in combination cancer therapy. PMID:28553108

Polysaccharide-based bioflocculant template of a diazotrophic Bradyrhizobium japonicum 36 for controlled assembly of AgCl nanoparticles.

PubMed

Rasulov, Bakhtiyor A; Pattaeva, Mohichehra A; Yili, Abulimiti; Aisa, Haji Akber

2016-08-01

A simple and green method was developed for the biosynthesis of silver chloride nanoparticles, free from silver nanoparticles, using polysaccharide-based bioflocculant of a diazotrophic rhizobacteria Bradyrhizobium japonicum 36 strain. The synthesized silver chloride nanoparticles were characterized by UV-vis, XRD, FT-IR and TEM. The concentration-dependent and controllable method for silver chloride nanoparticles was developed. The biosynthesized silver chloride nanoparticles exhibited strong antimicrobial activity towards pathogenic microorganisms such as Escherichia coli, Staphylococcus aureus and Candida albicans. The synthesized silver chloride nanoparticles can be exploited as a promising new biocide bionanocomposite against pathogenic microorganisms. Copyright © 2016 Elsevier B.V. All rights reserved.

Radiation Resistant Electrical Insulation Materials for Nuclear Reactors: Final Report

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

Duckworth, Robert C.; Aytug, Tolga; Paranthaman, M. Parans

The instrument and control cables in future nuclear reactors will be exposed to temperatures, dose rates, and accumulated doses exceeding those originally anticipated for the 40-year operational life of the nuclear power plant fleet. The use of nanocomposite dielectrics as insulating material for such cables has been considered a route to performance improvement. In this project, nanoparticles were developed and successfully included in three separate material systems [cross-linked polyvinyl alcohol (PVA/XLPVA), cross-linked polyethylene (PE/XLPE), and polyimide (PI)], and the chemical, electrical, and mechanical performance of each was analyzed as a function of environmental exposure and composition. Improvements were found inmore » each material system; however, refinement of each processing pathway is needed, and the consequences of these refinements in the context of thermal, radiation, and moisture exposures should be evaluated before transferring knowledge to industry.« less

Photoinitiated Polymerization-Induced Self-Assembly of Glycidyl Methacrylate for the Synthesis of Epoxy-Functionalized Block Copolymer Nano-Objects.

PubMed

Tan, Jianbo; Liu, Dongdong; Huang, Chundong; Li, Xueliang; He, Jun; Xu, Qin; Zhang, Li

2017-08-01

Herein, a novel photoinitiated polymerization-induced self-assembly formulation via photoinitiated reversible addition-fragmentation chain transfer dispersion polymerization of glycidyl methacrylate (PGMA) in ethanol-water at room temperature is reported. It is demonstrated that conducting polymerization-induced self-assembly (PISA) at low temperatures is crucial for obtaining colloidal stable PGMA-based diblock copolymer nano-objects. Good control is maintained during the photo-PISA process with a high rate of polymerization. The polymerization can be switched between "ON" and "OFF" in response to visible light. A phase diagram is constructed by varying monomer concentration and degree of polymerization. The PGMA-based diblock copolymer nano-objects can be further cross-linked by using a bifunctional primary amine reagent. Finally, silver nanoparticles are loaded within cross-linked vesicles via in situ reduction, exhibiting good catalytic properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vascular targeting of a gold nanoparticle to breast cancer metastasis

PubMed Central

Peiris, Pubudu M.; Deb, Partha; Doolittle, Elizabeth; Doron, Gilad; Goldberg, Amy; Govender, Priya; Shah, Shruti; Rao, Swetha; Carbone, Sarah; Cotey, Thomas; Sylvestre, Meilyn; Singh, Sohaj; Schiemann, William P.; Lee, Zhenghong; Karathanasis, Efstathios

2015-01-01

The vast majority of breast cancer deaths are due to metastatic disease. While deep tissue targeting of nanoparticles is suitable for some primary tumors, vascular targeting may be a more attractive strategy for micrometastasis. This study combined a vascular targeting strategy with the enhanced targeting capabilities of a nanoparticle to evaluate the ability of a gold nanoparticle to specifically target the early spread of metastatic disease. As a ligand for the vascular targeting strategy, we utilized a peptide targeting alpha(v) beta(3) integrin, which is functionally linked to the development of micrometastases at a distal site. By employing a straightforward radiolabeling method to incorporate Technetium-99m into the gold nanoparticles, we used the high sensitivity of radionuclide imaging to monitor the longitudinal accumulation of the nanoparticles in metastatic sites. Animal and histological studies showed that vascular targeting of the nanoparticle facilitated highly accurate targeting of micrometastasis in the 4T1 mouse model of breast cancer metastasis using radionuclide imaging and a low dose of the nanoparticle. Due to the efficient targeting scheme, 14% of the injected AuNP deposited at metastatic sites in the lungs within 60 min after injection, indicating that the vascular bed of metastasis is a viable target site for nanoparticles. PMID:26036431

Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles.

PubMed

Lavado, Andrea S; Chauhan, Veeren M; Zen, Amer Alhaj; Giuntini, Francesca; Jones, D Rhodri E; Boyle, Ross W; Beeby, Andrew; Chan, Weng C; Aylott, Jonathan W

2015-09-14

Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(II) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(II) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(II) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.

Biomimetic assembly of polypeptide-stabilized CaCO(3) nanoparticles.

PubMed

Zhang, Zhongping; Gao, Daming; Zhao, Hui; Xie, Chenggen; Guan, Guijian; Wang, Dapeng; Yu, Shu-Hong

2006-05-04

In this paper, we report a simple polypeptide-directed strategy for fabricating large spherical assembly of CaCO(3) nanoparticles. Stepwise growth and assembly of a large number of nanoparticles have been observed, from the formation of an amorphous liquidlike CaCO(3)-polypeptide precursor, to the crystallization and stabilization of polypeptide-capped nanoparticles, and eventually, the spherical assembly of nanoparticles. The "soft" poly(aspartate)-capping layer binding on a nanoparticle surface resulted in the unusual soft nature of nanoparticle assembly, providing a reservoir of primary nanoparticles with a moderate mobility, which is the basis of a new strategy for reconstructing nanoparticle assembly into complex nanoparticle architectures. Moreover, the findings of the secondary assembly of nanoparticle microspheres and the morphology transformation of nanoparticle assembly demonstrate a flexible and controllable pathway for manipulating the shapes and structures of nanoparticle assembly. In addition, the combination of the polypeptide with a double hydrophilic block copolymer (DHBC) allows it to possibly further control the shape and complexity of the nanoparticle assembly. A clear perspective is shown here that more complex nanoparticle materials could be created by using "soft" biological proteins or peptides as a mediating template at the organic-inorganic interface.

Enhancement of MHC-I antigen presentation via architectural control of pH-responsive, endosomolytic polymer nanoparticles.

PubMed

Wilson, John T; Postma, Almar; Keller, Salka; Convertine, Anthony J; Moad, Graeme; Rizzardo, Ezio; Meagher, Laurence; Chiefari, John; Stayton, Patrick S

2015-03-01

Protein-based vaccines offer a number of important advantages over organism-based vaccines but generally elicit poor CD8(+) T cell responses. We have previously demonstrated that pH-responsive, endosomolytic polymers can enhance protein antigen delivery to major histocompatibility complex class I (MHC-I) antigen presentation pathways thereby augmenting CD8(+) T cell responses following immunization. Here, we describe a new family of nanocarriers for protein antigen delivery assembled using architecturally distinct pH-responsive polymers. Reversible addition-fragmentation chain transfer (RAFT) polymerization was used to synthesize linear, hyperbranched, and core-crosslinked copolymers of 2-(N,N-diethylamino)ethyl methacrylate (DEAEMA) and butyl methacrylate (BMA) that were subsequently chain extended with a hydrophilic N,N-dimethylacrylamide (DMA) segment copolymerized with thiol-reactive pyridyl disulfide (PDS) groups. In aqueous solution, polymer chains assembled into 25 nm micellar nanoparticles and enabled efficient and reducible conjugation of a thiolated protein antigen, ovalbumin. Polymers demonstrated pH-dependent membrane-destabilizing activity in an erythrocyte lysis assay, with the hyperbranched and cross-linked polymer architectures exhibiting significantly higher hemolysis at pH ≤ 7.0 than the linear diblock. Antigen delivery with the hyperbranched and cross-linked polymer architecture enhanced in vitro MHC-I antigen presentation relative to free antigen, whereas the linear construct did not have a discernible effect. The hyperbranched system elicited a four- to fivefold increase in MHC-I presentation relative to the cross-linked architecture, demonstrating the superior capacity of the hyperbranched architecture in enhancing MHC-I presentation. This work demonstrates that the architecture of pH-responsive, endosomolytic polymers can have dramatic effects on intracellular antigen delivery, and offers a promising strategy for enhancing CD8(+) T cell responses to protein-based vaccines.

Self-assembled silver nanoparticle films at an air-liquid interface and their applications in SERS and electrochemistry

NASA Astrophysics Data System (ADS)

Wang, Li; Sun, Yujing; Che, Guangbo; Li, Zhuang

2011-06-01

In this paper, we present a novel technique to prepare silver nanoparticle films by controlling the self-assembly of nanoparticles at an air-liquid interface. In an ethanol-water phase, silver nanoparticles were prepared by reduction of AgNO 3 aqueous solution with NaBH 4 in the presence of cinnamic acid. It was found that the silver nanoparticles in this process could be trapped at the air-liquid interface to form 2-dimensional nanoparticle films. The morphology of nanoparticle films could be controlled by systematic variation of the experimental parameters. It is worth noting that the nanoparticle films could serve as the active substrates for surface-enhanced Raman scattering (SERS). 4-Aminothiophenol (4-ATP) molecule was used as a test probe to investigate the SERS sensitivity of different nanoparticle films. The results indicated that the nanoparticle films showed excellent Raman enhancement effect. Furthermore, the nanoparticle films prepared by our strategy were found to be efficient electrocatalysts for anodic oxidation of formaldehyde in alkaline medium.

Strong-Field Driven Dynamics of Metal and Dielectric Nanoparticles

NASA Astrophysics Data System (ADS)

Powell, Jeffrey

The motion of electrons in atoms, molecules, and solids in the presence of intense electromagnetic radiation is an important research topic in physics and physical chemistry because of its fundamental nature and numerous practical applications, ranging from precise machining of materials to optical control of chemical reactions and light-driven electronic devices. Mechanisms of light-matter interactions critically depend on the dimensions of the irradiated system and evolve significantly from single atoms or molecules to the macroscopic bulk. Nanoparticles provide the link between these two extremes. In this thesis, I take advantage of this bridge to study light-matter interactions as a function of nanoparticle size, shape, and composition. I present here three discrete, but interconnected, experiments contributing to our knowledge of nanoparticle properties and their response to intense, short-pulsed light fields. First, I investigate how individual nanoparticles interact with each other in solution, studying their temperature-dependent solubility. The interaction potential between 5.5nm gold nanoparticles, ligated by an alkanethiol was found to be -0.165eV, in reasonable agreement with a phenomenological model. The other two experiments explore ultrafast dynamics driven by intense femtosecond lasers in isolated, gas-phase metallic and dielectric nanoparticles. Photoelectron momentum imaging is applied to study the response of gold, silica, and gold-shell/silica-core nanoparticles (ranging from single to several hundred nanometers in size) with near-infrared (NIR), 25 fs laser pulses in the intensity range of 1011 - 1014 W/cm2. These measurements, which constitute the bulk of my graduate work, reveal the complex interplay between the external optical field and the induced near-field of the nanoparticle, resulting in the emission of very energetic electrons that are much faster than those emitted from isolated atoms or molecules exposed to the same light pulses. The highest photoelectron energies ("cutoffs") were measured as a function of laser intensity, nanoparticle material and size. We found that the energy cutoffs increase monotonically with laser intensity and nanoparticle size, except for the gold/silica hybrid where the plasmon resonance response modifies this behavior at low intensities. The measured photoelectron spectra for metallic nanoparticles display a large energy enhancement over silica. Finally, the last part of this thesis explores the possibility to apply time-resolved x-ray scattering as a probe of the ultrafast dynamics in isolated nanoparticles driven by very intense ( 1015 W/cm2) NIR laser radiation. To do this, I developed and built a nanoparticle source capable of injecting single, gas-phase nanoparticles with a narrow size distribution into the laser focus. We used femtosecond x-ray pulses from an x-ray free electron laser (XFEL) to map the evolution of the laser-irradiated nanoparticle. The ultrafast dynamics were observed in the single-shot x-ray diffraction patterns measured as a function of delay between the NIR and x-ray pulses, which allows for femtosecond temporal and nanometer spatial resolution. We found that the intense IR laser pulse rapidly ionizes the nanoparticle, effectively turning it into a nanoplasma within less than a picosecond, and observed signatures of the nanoparticle surface softening on a few hundred-femtosecond time scale.

Recent advances in chemical functionalization of nanoparticles with biomolecules for analytical applications.

PubMed

Oh, Ju-Hwan; Park, Do Hyun; Joo, Jang Ho; Lee, Jae-Seung

2015-11-01

The recent synthetic development of a variety of nanoparticles has led to their widespread application in diagnostics and therapeutics. In particular, the controlled size and shape of nanoparticles precisely determine their unique chemical and physical properties, which is highly attractive for accurate analysis of given systems. In addition to efforts toward controlling the synthesis and properties of nanoparticles, the surface functionalization of nanoparticles with biomolecules has been intensively investigated since the mid-1990s. The complicated yet programmable properties of biomolecules have proved to substantially enhance and enrich the novel functions of nanoparticles to achieve "smart" nanoparticle materials. In this review, the advances in chemical functionalization of four types of representative nanoparticle with DNA and protein molecules in the past five years are critically reviewed, and their future trends are predicted.

Gold nanoparticle-based optical microfluidic sensors for analysis of environmental pollutants.

PubMed

Lafleur, Josiane P; Senkbeil, Silja; Jensen, Thomas G; Kutter, Jörg P

2012-11-21

Conventional methods of environmental analysis can be significantly improved by the development of portable microscale technologies for direct in-field sensing at remote locations. This report demonstrates the vast potential of gold nanoparticle-based microfluidic sensors for the rapid, in-field, detection of two important classes of environmental contaminants - heavy metals and pesticides. Using gold nanoparticle-based microfluidic sensors linked to a simple digital camera as the detector, detection limits as low as 0.6 μg L(-1) and 16 μg L(-1) could be obtained for the heavy metal mercury and the dithiocarbamate pesticide ziram, respectively. These results demonstrate that the attractive optical properties of gold nanoparticle probes combine synergistically with the inherent qualities of microfluidic platforms to offer simple, portable and sensitive sensors for environmental contaminants.

Confined Pattern-Directed Assembly of Polymer-Grafted Nanoparticles in a Phase Separating Blend with a Homopolymer Matrix.

PubMed

Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Douglas, Jack F; Stafford, Christopher M; Kumar, Sanat K; Raghavan, Dharmaraj; Karim, Alamgir

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation process through directed nanoparticle assembly. In particular, we consider isothermally annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in a poly(methyl methacrylate) (PMMA) matrix. Classic binary polymer blend phase separation related morphology transitions, from discrete AuPS domains to bicontinuous to inverse domain structure with increasing nanoparticle composition is observed, yet the kinetics of the AuPS/PMMA polymer blends system exhibit unique features compared to the parent PS/PMMA homopolymer blend. We further illustrate how to pattern-align the phase-separated AuPS nanoparticle domain shape, size and location through the imposition of a simple and novel external symmetry-breaking perturbation via soft-lithography. Specifically, submicron-sized topographically patterned elastomer confinement is introduced to direct the nanoparticles into kinetically controlled long-range ordered domains, having a dense yet well-dispersed distribution of non-crystallizing nanoparticles. The simplicity, versatility and roll-to-roll adaptability of this novel method for controlled nanoparticle assembly should make it useful in creating desirable patterned nanoparticle domains for a variety of functional materials and applications.

Nanobiophotonics for molecular imaging of cancer: Au- and Ag-based Epidermal Growth Factor receptor (EGFR) specific nanoprobes

NASA Astrophysics Data System (ADS)

Lucas, Leanne J.; Hewitt, Kevin C.

2012-03-01

Our aim is to create and validate a novel SERS-based nanoprobe for optical imaging of the epidermal growth factor receptor (EGFR). Gold and silver nanoparticles (Au/AgNPs) of various sizes were synthesized and coupled to epidermal growth factor (EGF) via a short ligand, α-lipoic acid (206 g/mol), which binds strongly to both Au and Ag nanoparticles via its disulfide end group. We used carbodiimide chemistry to couple EGF to α-lipoic acid. These nanoprobes were tested for binding affinity using Enzyme Linked ImmunoSorbent Assay (ELISA) and, in-vitro, using EGFRoverexpressing A431 cells. The nanoprobes show excellent EGFR-specific binding. Time of Flight Mass Spectrometry demonstrate the carbodiimide based linking of the carboxylic acid end-group of α-lipoic acid to one or more of the three (terminal, or 2 lysine) amine groups on EGF. ELISA confirms that the linked EGF is active by itself, and following conjugation with gold or silver nanoparticles. Compared with bare nanoparticles, UV-Vis spectroscopy of Ag-based nanoprobes exhibit significant plasmon red-shift, while there was no discernable shift for Au-based ones. Dark field microscopy shows abundant uptake by EGFR overexpressing A431 cells, and serves to further confirm the excellent binding affinity. Nanoprobe internalization and consequent aggregation is thought to be the basis of enhanced light scattering in the dark field images, supporting the notion that these nanoprobes should provide excellent SERS signals at all nanoprobe sizes. In summary, novel EGFR-specific nanoprobes have been synthesized and validated by standard assay and in cell culture for use as SERS optical imaging probes.

Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis.

PubMed

Andreotti, Agda Marobo; Goiato, Marcelo Coelho; Moreno, Amália; Nobrega, Adhara Smith; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline

2014-01-01

The aim of this study was to assess the effect of adding nanoparticles to N1 acrylic resin intended for artificial sclera, in terms of the color stability, microhardness, and flexural strength of the resin. Three hundred samples of N1 acrylic resin were used: 100 samples for color stability and microhardness tests (each test was performed on the opposite side of each sample), and 200 samples for flexural strength testing (100 samples before and after 1,008 hours of accelerated aging). Samples for each test were separated into ten groups (n=10), ie, without nanoparticles (control group) or with nanoparticles of zinc oxide, titanium dioxide (TiO₂), and barium sulfate at weight concentrations of 1%, 2%, and 2.5% (nanoparticle groups). Data were subjected to statistical analysis with nested analysis of variance and Tukey's test (P<0.05 significance level). Among the nanoparticle groups, the TiO₂ groups showed better color stability at all concentrations. Microhardness values increased after artificial aging, except for the control and zinc oxide groups. After aging, the 1%-2% TiO₂ groups had significantly higher microhardness values compared with the other nanoparticle groups. Before aging, there was a significant difference in flexural strength between the control and nanoparticle groups. After aging, the control and TiO₂ groups, regardless of concentration, showed the lowest flexural strength values. Incorporation of nanoparticles directly influenced the acrylic resin properties, with TiO₂ being the most influential nanoparticle in terms of the evaluated properties.

Bovine serum albumin nanoparticles as controlled release carrier for local drug delivery to the inner ear

NASA Astrophysics Data System (ADS)

Yu, Zhan; Yu, Min; Zhang, Zhibao; Hong, Ge; Xiong, Qingqing

2014-07-01

Nanoparticles have attracted increasing attention for local drug delivery to the inner ear recently. Bovine serum albumin (BSA) nanoparticles were prepared by desolvation method followed by glutaraldehyde fixation or heat denaturation. The nanoparticles were spherical in shape with an average diameter of 492 nm. The heat-denatured nanoparticles had good cytocompatibility. The nanoparticles could adhere on and penetrate through the round window membrane of guinea pigs. The nanoparticles were analyzed as drug carriers to investigate the loading capacity and release behaviors. Rhodamine B was used as a model drug in this paper. Rhodamine B-loaded nanoparticles showed a controlled release profile and could be deposited on the osseous spiral lamina. We considered that the bovine serum albumin nanoparticles may have potential applications in the field of local drug delivery in the treatment of inner ear disorders.

Tumour homing and therapeutic effect of colloidal nanoparticles depend on the number of attached antibodies

PubMed Central

Colombo, Miriam; Fiandra, Luisa; Alessio, Giulia; Mazzucchelli, Serena; Nebuloni, Manuela; De Palma, Clara; Kantner, Karsten; Pelaz, Beatriz; Rotem, Rany; Corsi, Fabio; Parak, Wolfgang J.; Prosperi, Davide

2016-01-01

Active targeting of nanoparticles to tumours can be achieved by conjugation with specific antibodies. Specific active targeting of the HER2 receptor is demonstrated in vitro and in vivo with a subcutaneous MCF-7 breast cancer mouse model with trastuzumab-functionalized gold nanoparticles. The number of attached antibodies per nanoparticle was precisely controlled in a way that each nanoparticle was conjugated with either exactly one or exactly two antibodies. As expected, in vitro we found a moderate increase in targeting efficiency of nanoparticles with two instead of just one antibody attached per nanoparticle. However, the in vivo data demonstrate that best effect is obtained for nanoparticles with only exactly one antibody. There is indication that this is based on a size-related effect. These results highlight the importance of precisely controlling the ligand density on the nanoparticle surface for optimizing active targeting, and that less antibodies can exhibit more effect. PMID:27991503

High Throughput Spectroscopic Catalyst Screening via Surface Plasmon Spectroscopy

DTIC Science & Technology

2015-07-15

release. Distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Over the last decade, shape controlled synthesis of nanoparticles (NPs) has...unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Over the last decade, shape controlled synthesis of nanoparticles (NPs) has opened up the possibility...i) Specific Aims - Over the last decade, shape controlled synthesis of nanoparticles (NPs) has opened up the possibility to study heterogeneous

Characterization of Polystyrene Soft Nanoparticles Using Small Angle Neutron Scattering

NASA Astrophysics Data System (ADS)

Martin, Halie; White, Tyler; Saito, Tomonori; Dadmun, Mark

Polymer nanocomposites have become a prominent area of research recently. With a growing variety of nanoparticles available, research probing the influence of particle morphology on the overall nanocomposite properties is also increasing. Nanoparticle dispersion is controlled by both the chemical nature and morphology of the nanoparticle where a crosslinked, fuzzy organic nanoparticle is anticipated to enhance the overall miscibility and create a homogenous dispersion within a like-polymer matrix. A semi-batch microemulsion polymerization forms organic, soft nanoparticles where the precise structure of the nanoparticle is controlled by monomer rate of addition and crosslinking density. We will report small angle neutron scattering results that correlate synthetic conditions to the structural characteristics of soft nanoparticles. This analysis provides characterization of the individual nanoparticle molecular weight, the radius of the crosslinked core, the thickness of the fuzzy interfacial layer, and provides insight into the overall topography of the soft nanoparticle. This research provides a pathway to investigate the effect of nanoscale structural features of the nanoparticle on their individual properties and those of nanocomposites that contain these soft nanoparticles. DOE-BES, Division of Materials Sciences and Engineering.

Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach.

PubMed

Shiba, K; Sugiyama, T; Takei, T; Yoshikawa, G

2015-11-11

Silica/titania-based functional nanoparticles were prepared through controlled nucleation of titania and subsequent encapsulation by silica through a multistep microfluidic approach, which was successfully applied to obtaining aminopropyl-functionalized silica/titania nanoparticles for a highly sensitive humidity sensor.

Encapsulation-free controlled release: Electrostatic adsorption eliminates the need for protein encapsulation in PLGA nanoparticles

PubMed Central

Pakulska, Malgosia M.; Elliott Donaghue, Irja; Obermeyer, Jaclyn M.; Tuladhar, Anup; McLaughlin, Christopher K.; Shendruk, Tyler N.; Shoichet, Molly S.

2016-01-01

Encapsulation of therapeutic molecules within polymer particles is a well-established method for achieving controlled release, yet challenges such as low loading, poor encapsulation efficiency, and loss of protein activity limit clinical translation. Despite this, the paradigm for the use of polymer particles in drug delivery has remained essentially unchanged for several decades. By taking advantage of the adsorption of protein therapeutics to poly(lactic-co-glycolic acid) (PLGA) nanoparticles, we demonstrate controlled release without encapsulation. In fact, we obtain identical, burst-free, extended-release profiles for three different protein therapeutics with and without encapsulation in PLGA nanoparticles embedded within a hydrogel. Using both positively and negatively charged proteins, we show that short-range electrostatic interactions between the proteins and the PLGA nanoparticles are the underlying mechanism for controlled release. Moreover, we demonstrate tunable release by modifying nanoparticle concentration, nanoparticle size, or environmental pH. These new insights obviate the need for encapsulation and offer promising, translatable strategies for a more effective delivery of therapeutic biomolecules. PMID:27386554

A facile and rapid method for the black pepper leaf mediated green synthesis of silver nanoparticles and the antimicrobial study

NASA Astrophysics Data System (ADS)

Augustine, Robin; Kalarikkal, Nandakumar; Thomas, Sabu

2014-10-01

Green synthesis of nanoparticles is widely accepted due to the less toxicity in comparison with chemical methods. But there are certain drawbacks like slow formation of nanoparticles, difficulty to control particle size and shape make them less convenient. Here we report a novel cost-effective and eco-friendly method for the rapid green synthesis of silver nanoparticles using leaf extracts of Piper nigrum. Our results suggest that this method can be used for obtaining silver nanoparticles with controllable size within a few minutes. The fabricated nanoparticles possessed excellent antibacterial property against both Gram-positive and Gram-negative bacteria.

Enhanced drug encapsulation and extended release profiles of calcium-alginate nanoparticles by using tannic acid as a bridging cross-linking agent.

PubMed

Abulateefeh, Samer R; Taha, Mutasem O

2015-01-01

Calcium alginate nanoparticles (NPs) suffer from sub-optimal stability in bio-relevant media leading to low drug encapsulation efficiency and uncontrolled release profiles. To sort out these drawbacks, a novel approach is proposed herein based on introducing tannic acid into these NPs to act as a bridging cross-linking aid agent. Calcium-alginate NPs were prepared by the ionotropic gelation method and loaded with diltiazem hydrochloride as a model drug. These NPs were characterized in terms of particle size, zeta potential, and morphology, and results were explained in accordance with Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The incorporation of tannic acid led to more than four folds increase in drug encapsulation efficiency (i.e. from 15.3% to 69.5%) and reduced burst drug release from 44% to around 10% within the first 30 min. These findings suggest the possibility of improving the properties of Ca-alginate NPs by incorporating cross-linking aid agents under mild conditions.

Size and composition-controlled fabrication of VO2 nanocrystals by terminated cluster growth

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

Anders, Andre; Slack, Jonathan

2013-05-14

A physical vapor deposition-based route for the fabrication of VO2 nanoparticles is demonstrated, consisting of reactive sputtering and vapor condensation at elevated pressures. The oxidation of vanadium atoms is an efficient heterogeneous nucleation method, leading to high nanoparticle throughtput. Fine control of the nanoparticle size and composition is obtained. Post growth annealing leads to crystalline VO2 nanoparticles with optimum thermocromic and plasmonic properties.

Controlling diameter distribution of catalyst nanoparticles in arc discharge.

PubMed

Li, Jian; Volotskova, Olga; Shashurin, Alexey; Keidar, Michael

2011-11-01

It is demonstrated that the diameter distribution of catalyst nanoparticles in arc discharge can be controlled by a magnetic field. The magnetic field affects the arc shape, shortens the diffusing time of the catalyst nanoparticles through the nucleation zone, and consequentially reduces the average diameters of nanoparticles. The average diameter is reduced from about 7.5 nm without magnetic field to about 5 nm is the case of a magnetic field. Decrease of the catalyst nanoparticle diameter with magnetic field correlates well with decrease in the single-wall carbon nanotube and their bundles diameters.

Surfactant-Free Shape Control of Gold Nanoparticles Enabled by Unified Theoretical Framework of Nanocrystal Synthesis.

PubMed

Wall, Matthew A; Harmsen, Stefan; Pal, Soumik; Zhang, Lihua; Arianna, Gianluca; Lombardi, John R; Drain, Charles Michael; Kircher, Moritz F

2017-06-01

Gold nanoparticles have unique properties that are highly dependent on their shape and size. Synthetic methods that enable precise control over nanoparticle morphology currently require shape-directing agents such as surfactants or polymers that force growth in a particular direction by adsorbing to specific crystal facets. These auxiliary reagents passivate the nanoparticles' surface, and thus decrease their performance in applications like catalysis and surface-enhanced Raman scattering. Here, a surfactant- and polymer-free approach to achieving high-performance gold nanoparticles is reported. A theoretical framework to elucidate the growth mechanism of nanoparticles in surfactant-free media is developed and it is applied to identify strategies for shape-controlled syntheses. Using the results of the analyses, a simple, green-chemistry synthesis of the four most commonly used morphologies: nanostars, nanospheres, nanorods, and nanoplates is designed. The nanoparticles synthesized by this method outperform analogous particles with surfactant and polymer coatings in both catalysis and surface-enhanced Raman scattering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biogenic silver nanoparticles based on trichoderma harzianum: synthesis, characterization, toxicity evaluation and biological activity

NASA Astrophysics Data System (ADS)

Guilger, Mariana; Pasquoto-Stigliani, Tatiane; Bilesky-Jose, Natália; Grillo, Renato; Abhilash, P. C.; Fraceto, Leonardo Fernandes; Lima, Renata De

2017-03-01

White mold is an agricultural disease caused by the fungus Sclerotinia sclerotiorum, which affects important crops. There are different ways of controlling this organism, but none provides inhibition of its resistance structures (sclerotia). Nanotechnology offers promising applications in agricultural area. Here, silver nanoparticles were biogenically synthesized using the fungus Trichoderma harzianum and characterized. Cytotoxicity and genotoxicity were evaluated, and the nanoparticles were initially tested against white mold sclerotia. Their effects on soybean were also investigated with no effects observed. The nanoparticles showed potential against S. sclerotiorum, inhibiting sclerotia germination and mycelial growth. Nanoparticle characterization data indicated spherical morphology, satisfactory polydispersity and size distribution. Cytotoxicity and genotoxicity assays showed that the nanoparticles caused both the effects, although, the most toxic concentrations were above those applied for white mold control. Given the potential of the nanoparticles against S. sclerotiorum, we conclude that this study presents a first step for a new alternative in white mold control.

Synthesis of NiFe2O4 nanoparticles for energy and environment applications

NASA Astrophysics Data System (ADS)

Zhang, Ying; Rimal, Gaurab; Tang, Jinke; Dai, Qilin

2018-02-01

Magnetic nanoparticles are of great interest due to their applications in energy and environment. In this work, we developed a chemical solution based method to synthesize NiFe2O4 (NFO) nanoparticles with different sizes and structures by organic ligands and studied their applications in magnetic electrolyte concentration cells and waste water treatment. NFO nanoparticle growth is controlled by the organic passivating ligand ratios, reaction temperatures, and reaction solution concentrations to achieve the control of NFO nanoparticle size ranging from 25 nm to 160 nm. The NFO growth mechanism is controlled by aggregation related mechanism, leading to tunable magnetic properties and concentration cell device performance. Magnetic biochar consisting of biochar/NFO composite was also obtained based on the developed method. Waste water containing Rhodamine B was tested by the synthesized magnetic biochar. We believe the method developed in this work about magnetic NFO nanoparticles and magnetic biochar will shed light on the application of magnetic nanoparticles in energy and environment.

Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

DOEpatents

Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

2012-07-03

In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

A highly sensitive nanoscale pH-sensor using Au nanoparticles linked by a multifunctional Raman-active reporter molecule

NASA Astrophysics Data System (ADS)

Lawson, Latevi S.; Chan, James W.; Huser, Thomas

2014-06-01

Chemical sensing on the nanoscale has been breaking new ground since the discovery of surface enhanced Raman scattering (SERS). For nanoparticles, controlled particle aggregation is necessary to achieve the largest SERS enhancements. Therefore, aggregating agents such as salts or linker molecules are used in conjunction with chemically sensitive reporters in order to develop robust environmentally sensitive SERS probes. While salt-induced colloidal nanosphere aggregates have produced robust SERS signals, their variability in aggregate size contributes significantly to poor SERS signal reproducibility, which can complicate their use in in vitro cellular studies. Such systems often also lack reproducibility in spectral measurements between different nanoparticle clusters. Preaggregation of colloids via linkers followed by surface functionalization with reporter molecules results in the linker occupying valuable SERS hotspot volume which could otherwise be utilized by additional reporter molecules. Ideally, both functionalities should be obtained from a single molecule. Here, we report the use of 3,5-dimercaptobenzoic acid, a single multifunctional molecule that creates SERS hotspots via the controlled aggregation of nanoparticles, and also reports pH values. We show that 3,5-dimercaptobenzoic acid bound to Au nanospheres results in an excellent pH nanoprobe, producing very robust, and highly reproducible SERS signals that can report pH across the entire physiological range with excellent pH resolution. To demonstrate the efficacy of our novel pH reporters, these probes were also used to image both the particle and pH distribution in the cytoplasm of human induced pluripotent stem cells (hiPSCs).Chemical sensing on the nanoscale has been breaking new ground since the discovery of surface enhanced Raman scattering (SERS). For nanoparticles, controlled particle aggregation is necessary to achieve the largest SERS enhancements. Therefore, aggregating agents such as salts or linker molecules are used in conjunction with chemically sensitive reporters in order to develop robust environmentally sensitive SERS probes. While salt-induced colloidal nanosphere aggregates have produced robust SERS signals, their variability in aggregate size contributes significantly to poor SERS signal reproducibility, which can complicate their use in in vitro cellular studies. Such systems often also lack reproducibility in spectral measurements between different nanoparticle clusters. Preaggregation of colloids via linkers followed by surface functionalization with reporter molecules results in the linker occupying valuable SERS hotspot volume which could otherwise be utilized by additional reporter molecules. Ideally, both functionalities should be obtained from a single molecule. Here, we report the use of 3,5-dimercaptobenzoic acid, a single multifunctional molecule that creates SERS hotspots via the controlled aggregation of nanoparticles, and also reports pH values. We show that 3,5-dimercaptobenzoic acid bound to Au nanospheres results in an excellent pH nanoprobe, producing very robust, and highly reproducible SERS signals that can report pH across the entire physiological range with excellent pH resolution. To demonstrate the efficacy of our novel pH reporters, these probes were also used to image both the particle and pH distribution in the cytoplasm of human induced pluripotent stem cells (hiPSCs). Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06277e

Controlled functionalization of nanoparticles & practical applications

NASA Astrophysics Data System (ADS)

Rashwan, Khaled

With the increasing use of nanoparticles in both science and industry, their chemical modification became a significant part of nanotechnology. Unfortunately, most commonly used procedures provide just randomly functionalized materials. The long-term objective of our work is site- and stoichiometrically-controlled functionalization of nanoparticles with the utilization of solid supports and other nanostructures. On the examples of silica nanoparticles and titanium dioxide nanorods, we have obtained results on the solid-phase chemistry, method development, and modeling, which advanced us toward this goal. At the same time, we explored several applications of nanoparticles that will benefit from the controlled functionalization: imaging of titanium-dioxide-based photocatalysts, bioimaging by fluorescent nanoparticles, drug delivery, assembling of bone implants, and dental compositions. Titanium dioxide-based catalysts are known for their catalytic activity and their application in solar energy utilization such as photosplitting of water. Functionalization of titanium dioxide is essential for enhancing bone-titanium dioxide nanotube adhesion, and, therefore, for its application as an interface between titanium implants and bones. Controlled functionalization of nanoparticles should enhance sensitivity and selectivity of nanoassemblies for imaging and drug delivery applications. Along those lines, we studied the relationship between morphology and surface chemistry of nanoparticles, and their affinity to organic molecules (salicylic and caffeic acid) using Langmuir adsorption isotherms, and toward material surfaces using SEM- and TEM-imaging. We focused on commercial samples of titanium dioxide, titanium dioxide nanorods with and without oleic acid ligands, and differently functionalized silica nanoparticles. My work included synthesis, functionalization, and characterization of several types of nanoparticles, exploring their application in imaging, dentistry, and bone implant construction. Significant part of my experimental efforts was devoted to the solid-phase method development using model organic molecules, as well as affinity of nanoparticles to the functional groups and surfaces that can be used as linkages for constructing functional nanodevices.

Carbamazepine-loaded solid lipid nanoparticles and nanostructured lipid carriers: Physicochemical characterization and in vitro/in vivo evaluation.

PubMed

Scioli Montoto, S; Sbaraglini, M L; Talevi, A; Couyoupetrou, M; Di Ianni, M; Pesce, G O; Alvarez, V A; Bruno-Blanch, L E; Castro, G R; Ruiz, M E; Islan, G A

2018-07-01

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) represent promising alternatives for drug delivery to the central nervous system. In the present work, four different nanoformulations of the antiepileptic drug Carbamazepine (CBZ) were designed and prepared by the homogenization/ultrasonication method, with encapsulation efficiencies ranging from 82.8 to 93.8%. The formulations remained stable at 4 °C for at least 3 months. Physicochemical and microscopic characterization were performed by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), atomic force microscopy (AFM); thermal properties by differential scanning calorimetry (DSC), thermogravimetry (TGA) and X-ray diffraction analysis (XRD). The results indicated the presence of spherical shape nanoparticles with a mean particle diameter around 160 nm in a narrow size distribution; the entrapped CBZ displayed an amorphous state. The in vitro release profile of CBZ fitted into a Baker-Lonsdale model for spherical matrices and almost the 100% of the encapsulated drug was released in a controlled manner during the first 24 h. The apparent permeability of CBZ-loaded nanoparticles through a cell monolayer model was similar to that of the free drug. In vivo experiments in a mice model of seizure suggested protection by CBZ-NLC against seizures for at least 2 h after intraperitoneal administration. The developed CBZ-loaded lipid nanocarriers displayed optimal characteristics of size, shape and drug release and possibly represent a promising tool to improve the treatment of refractory epilepsy linked to efflux transporters upregulation. Copyright © 2018 Elsevier B.V. All rights reserved.

Controllable g5p-Protein-Directed Aggregation of ssDNA-Gold Nanoparticles

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

Lee, S.; Maye, M; Zhang, Y

We assembled single-stranded DNA (ssDNA) conjugated nanoparticles using the phage M13 gene 5 protein (g5p) as the molecular glue to bind two antiparallel noncomplementary ssDNA strands. The entire process was controlled tightly by the concentration of the g5p protein and the presence of double-stranded DNA. The g5p-ssDNA aggregate was disintegrated by hybridization with complementary ssDNA (C-ssDNA) that triggers the dissociation of the complex. Polyhistidine-tagged g5p was bound to nickel nitrilotriacetic acid (Ni2+-NTA) conjugated nanoparticles and subsequently used to coassemble the ssDNA-conjugated nanoparticles into multiparticle-type aggregates. Our approach offers great promise for designing biologically functional, controllable protein/nanoparticle composites.

Supramolecular Hydrogel from Nanoparticles and Cyclodextrins for Local and Sustained Nanoparticle Delivery.

PubMed

Xu, Shuxin; Yin, Li; Xiang, Yuzhang; Deng, Hongzhang; Deng, Liandong; Fan, Hongxia; Tang, Hua; Zhang, Jianhua; Dong, Anjie

2016-08-01

Injectable and biodegradable supramolecular hydrogel mPECT NP/α-CD(gel) composed of high-concentration nanoparticle dispersion (≤20% W/V) and α-cyclodextrins (α-CD) are prepared by a two-level physical cross-linking using amphiphilic block polymer methoxy poly(ethylene glycol)-b-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (mPECT) and α-CD. The gelation behavior depends on the concentration of nanoparticles and α-CD. The viscoelasticity and shear thinning of mPECT NP/α-CD(gel) are confirmed. In vitro hydrogel erosion is demonstrated to be mainly a concentration-dependent dissociation process with general release of discrete mPECT nanoparticles about 50 nm that can be easily taken up by cells. The in vitro release behavior can be modulated by changing the concentration of nanoparticles or α-CD. In vitro and in vivo cytotoxicity study demonstrates its biocompatibility and biosafety. Gel formation after subcutaneous injection is also confirmed and mPECT NP/α-CD(gel) shows about 2 weeks retention time. This work validates the potential application for this supramolecular hydrogel in local and sustained delivery of nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clean Photothermal Heating and Controlled Release from Near-Infrared Dye Doped Nanoparticles without Oxygen Photosensitization.

PubMed

Guha, Samit; Shaw, Scott K; Spence, Graeme T; Roland, Felicia M; Smith, Bradley D

2015-07-21

The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of (1)O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive (1)O2, leading to bleaching of the dye and also decomposition of coencapsulated payload such as the drug doxorubicin. Croc dye was especially useful as a photothermal agent for laser-controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water-soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications.

Clean Photothermal Heating and Controlled Release From Near Infrared Dye Doped Nanoparticles Without Oxygen Photosensitization

PubMed Central

Guha, Samit; Shaw, Scott K.; Spence, Graeme T.; Roland, Felicia M.; Smith, Bradley D.

2015-01-01

The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer-hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of 1O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive 1O2 leading to bleaching of the dye and also decomposition of co-encapsulated payload such as the drug Doxorubicin. Croc dye was especially useful as a photothermal agent for laser controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications. PMID:26149326

Development of thermosensitive poly(n-isopropylacrylamide-co-((2-dimethylamino) ethyl methacrylate))-based nanoparticles for controlled drug release

NASA Astrophysics Data System (ADS)

Peng, Cheng-Liang; Tsai, Han-Min; Yang, Shu-Jyuan; Luo, Tsai-Yueh; Lin, Chia-Fu; Lin, Wuu-Jyh; Shieh, Ming-Jium

2011-07-01

Thermosensitive nanoparticles based on poly(N-isopropylacrylamide-co-((2-dimethylamino)ethylmethacrylate)) (poly(NIPA-co-DMAEMA)) copolymers were successfully fabricated by free radical polymerization. The lower critical solution temperature (LCST) of the synthesized nanoparticles was 41 °C and a temperature above which would cause the nanoparticles to undergo a volume phase transition from 140 to 100 nm, which could result in the expulsion of encapsulated drugs. Therefore, we used the poly(NIPA-co-DMAEMA) nanoparticles as a carrier for the controlled release of a hydrophobic anticancer agent, 7-ethyl-10-hydroxy-camptothecin (SN-38). The encapsulation efficiency and loading content of SN-38-loaded nanoparticles at an SN-38/poly(NIPA-co-DMAEMA) ratio of 1/10 (D/P = 1/10) were about 80% and 6.293%, respectively. Moreover, the release profile of SN-38-loaded nanoparticles revealed that the release rate at 42 °C (above LCST) was higher than that at 37 °C (below LCST), which demonstrated that the release of SN-38 could be controlled by increasing the temperature. The cytotoxicity of the SN-38-loaded poly(NIPA-co-DMAEMA) nanoparticles was investigated in human colon cancer cells (HT-29) to compare with the treatment of an anticancer drug, Irinotecan® (CPT-11). The antitumor efficacy evaluated in a C26 murine colon tumor model showed that the SN-38-loaded nanoparticles in combination with hyperthermia therapy efficiently suppressed tumor growth. The results indicate that these thermo-responsive nanoparticles are potential carriers for controlled drug delivery.

EDTA functionalized magnetic nanoparticle as a multifunctional adsorbent for Congo red dye from contaminated water

NASA Astrophysics Data System (ADS)

Sahoo, Jitendra Kumar; Rath, Juhi; Dash, Priyabrat; Sahoo, Harekrushna

2017-05-01

The present work reports the applicability of magnetite iron nanoparticles (Fe3O4) functionalized with ethylenediaminetetraacetic acid (EDTA) as an efficient adsorbent for the removal of Congo red (CR) dye from contaminated water. Magnetic nanoparticles (Fe3O4) are prepared by chemical precipitation method in which Fe2+ and Fe3+ salt from aqueous solution were reacted in presence of ammonia solution. The surface of Fe3O4 nanoparticle was first coated with (3-aminopropyl) triethoxy silane (APTES) by a salinization reaction and then linked with EDTA via reaction between -NH2 and -COOH to form well dispersed surface functionalised biocompatible magnetic nanoparticles. The obtained EDTA functionalized magnetic nanoparticles are characterized in terms of their morphological, XRD, BET surface area analysis, Fourier transform infrared spectroscopy (FT-IR) and Vibrating sample magnetometer (VSM). The adsorption of CR on Fe3O4-APTES-EDTA nanocomposite corresponds well to the Langmuir model and the Freundlich model respectively. The adsorption processes for CR followed the pseudo-second-order model.

Synthesis of multivalent sialyllactosamine-carrying glyco-nanoparticles with high affinity to the human influenza virus hemagglutinin.

PubMed

Ogata, Makoto; Umemura, Seiichiro; Sugiyama, Naohiro; Kuwano, Natsuki; Koizumi, Ami; Sawada, Tadakazu; Yanase, Michiyo; Takaha, Takeshi; Kadokawa, Jun-Ichi; Usui, Taichi

2016-11-20

A series of multivalent sialoglyco-conjugated nanoparticles were efficiently synthesized by using highly-branched α-glucuronic acid-linked cyclic dextrins (GlcA-HBCD) as a backbone. The sialoglycoside-moieties, with varying degrees of substitution, could be incorporated onto the preformed nanoparticles. These synthesized particles, which are highly soluble in aqueous solution, were shown to have a spherical nanostructure with a diameter of approximately 15nm. The interactions of the sialoglyco-nanoparticles (Neu5Acα2,6LacNAc-GlcA-HBCDs) with human influenza virus strain A/Beijing/262/95 (H1N1) were investigated using a hemagglutination inhibition assay. The sialoglyco-nanoparticle, in which the number of sialic acid substitution is 30, acted as a powerful inhibitor of virus binding activity. We show that both distance and multiplicity of effective ligand-virus formation play important roles in enhancing viral inhibition. Our results indicate that the GlcA-HBCD backbone can be used as a novel spherical nanocluster material for preparing a variety of glyco-nanoparticles to facilitate molecular recognition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reduced Graphene Oxide-Based Silver Nanoparticle-Containing Composite Hydrogel as Highly Efficient Dye Catalysts for Wastewater Treatment

PubMed Central

Jiao, Tifeng; Guo, Haiying; Zhang, Qingrui; Peng, Qiuming; Tang, Yongfu; Yan, Xuehai; Li, Bingbing

2015-01-01

New reduced graphene oxide-based silver nanoparticle-containing composite hydrogels were successfully prepared in situ through the simultaneous reduction of GO and noble metal precursors within the GO gel matrix. The as-formed hydrogels are composed of a network structure of cross-linked nanosheets. The reported method is based on the in situ co-reduction of GO and silver acetate within the hydrogel matrix to form RGO-based composite gel. The stabilization of silver nanoparticles was also achieved simultaneously within the gel composite system. The as-formed silver nanoparticles were found to be homogeneously and uniformly dispersed on the surface of the RGO nanosheets within the composite gel. More importantly, this RGO-based silver nanoparticle-containing composite hydrogel matrix acts as a potential catalyst for removing organic dye pollutants from an aqueous environment. Interestingly, the as-prepared catalytic composite matrix structure can be conveniently separated from an aqueous environment after the reaction, suggesting the potentially large-scale applications of the reduced graphene oxide-based nanoparticle-containing composite hydrogels for organic dye removal and wastewater treatment. PMID:26183266

Vascular Targeting of a Gold Nanoparticle to Breast Cancer Metastasis.

PubMed

Peiris, Pubudu M; Deb, Partha; Doolittle, Elizabeth; Doron, Gilad; Goldberg, Amy; Govender, Priya; Shah, Shruti; Rao, Swetha; Carbone, Sarah; Cotey, Thomas; Sylvestre, Meilyn; Singh, Sohaj; Schiemann, William P; Lee, Zhenghong; Karathanasis, Efstathios

2015-08-01

The vast majority of breast cancer deaths are due to metastatic disease. Although deep tissue targeting of nanoparticles is suitable for some primary tumors, vascular targeting may be a more attractive strategy for micrometastasis. This study combined a vascular targeting strategy with the enhanced targeting capabilities of a nanoparticle to evaluate the ability of a gold nanoparticle (AuNP) to specifically target the early spread of metastatic disease. As a ligand for the vascular targeting strategy, we utilized a peptide targeting alpha(v) beta(3) integrin, which is functionally linked to the development of micrometastases at a distal site. By employing a straightforward radiolabeling method to incorporate Technetium-99m into the AuNPs, we used the high sensitivity of radionuclide imaging to monitor the longitudinal accumulation of the nanoparticles in metastatic sites. Animal and histological studies showed that vascular targeting of the nanoparticle facilitated highly accurate targeting of micrometastasis in the 4T1 mouse model of breast cancer metastasis using radionuclide imaging and a low dose of the nanoparticle. Because of the efficient targeting scheme, 14% of the injected AuNP deposited at metastatic sites in the lungs within 60 min after injection, indicating that the vascular bed of metastasis is a viable target site for nanoparticles. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Facile fabrication of core-in-shell particles by the slow removal of the core and its use in the encapsulation of metal nanoparticles.

PubMed

Choi, Won San; Koo, Hye Young; Kim, Dong-Yu

2008-05-06

Core-in-shell particles with controllable core size have been fabricated from core-shell particles by means of the controlled core-dissolution method. These cores in inorganic shells were employed as scaffolds for the synthesis of metal nanoparticles. After dissolution of the cores, metal nanoparticles embedded in cores were encapsulated into the interior of shell, without any damage or change. This article describes a very simple method for deriving core-in-shell particles with controllable core size and encapsulation of nanoparticles into the interior of shell.

Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles.

PubMed

Wu, Pae C; Khoury, Christopher G; Kim, Tong-Ho; Yang, Yang; Losurdo, Maria; Bianco, Giuseppe V; Vo-Dinh, Tuan; Brown, April S; Everitt, Henry O

2009-09-02

Size-controlled gallium nanoparticles deposited on sapphire were explored as alternative substrates to enhance Raman spectral signatures. Gallium's resilience following oxidation is inherently advantageous in comparison with silver for practical ex vacuo nonsolution applications. Ga nanoparticles were grown using a simple molecular beam epitaxy-based fabrication protocol, and monitoring their corresponding surface plasmon resonance energy through in situ spectroscopic ellipsometry allowed the nanoparticles to be easily controlled for size. The Raman spectra obtained from cresyl fast violet (CFV) deposited on substrates with differing mean nanoparticle sizes represent the first demonstration of enhanced Raman signals from reproducibly tunable self-assembled Ga nanoparticles. Nonoptimized aggregate enhancement factors of approximately 80 were observed from the substrate with the smallest Ga nanoparticles for CFV dye solutions down to a dilution of 10 ppm.

Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles

PubMed Central

Wu, Pae C; Khoury, Christopher G.; Kim, Tong-Ho; Yang, Yang; Losurdo, Maria; Bianco, Giuseppe V.; Vo-Dinh, Tuan; Brown, April S.; Everitt, Henry O.

2009-01-01

Size-controlled gallium nanoparticles deposited on sapphire are explored as alternative substrates to enhance Raman spectral signatures. Gallium’s resilience following oxidation is inherently advantageous compared to silver for practical ex vacuo, non-solution applications. Ga nanoparticles are grown using a simple, molecular beam epitaxy-based fabrication protocol, and by monitoring their corresponding surface plasmon resonance energy through in situ spectroscopic ellipsometry, the nanoparticles are easily controlled for size. Raman spectroscopy performed on cresyl fast violet (CFV) deposited on substrates of differing mean nanoparticle size represents the first demonstration of enhanced Raman signals from reproducibly tunable self-assembled Ga nanoparticles. Non-optimized aggregate enhancement factors of ~80 were observed from the substrate with the smallest Ga nanoparticles for CFV dye solutions down to a dilution of 10 ppm. PMID:19655747

Nanoparticle Imaging of Integrins on Tumor Cells1

PubMed Central

Montet, Xavier; Montet-Abou, Karin; Reynolds, Fred; Weissleder, Ralph; Josephson, Lee

2006-01-01

Abstract Nanoparticles 10 to 100 nm in size can deliver large payloads to molecular targets, but undergo slow diffusion and/or slow transport through delivery barriers. To examine the feasibility of nanoparticles targeting a marker expressed in tumor cells, we used the binding of cyclic arginine-glycine-aspartic acid (RGD) nanoparticle targeting integrins on BT-20 tumor as a model system. The goals of this study were: 1) to use nanoparticles to image αvβ3 integrins expressed in BT-20 tumor cells by fluorescence-based imaging and magnetic resonance imaging, and, 2) to identify factors associated with the ability of nanoparticles to target tumor cell integrins. Three factors were identified: 1) tumor cell integrin expression (the αvβ3 integrin was expressed in BT-20 cells, but not in 9L cells); 2) nanoparticle pharmacokinetics (the cyclic RGD peptide cross-linked iron oxide had a blood half-life of 180 minutes and was able to escape from the vasculature over its long circulation time); and 3) tumor vascularization (the tumor had a dense capillary bed, with distances of <100 µm between capillaries). These results suggest that nanoparticles could be targeted to the cell surface markers expressed in tumor cells, at least in the case wherein the nanoparticles and the tumor model have characteristics similar to those of the BT-20 tumor employed here. PMID:16611415

Visualisation of morphological interaction of diamond and silver nanoparticles with Salmonella Enteritidis and Listeria monocytogenes.

PubMed

Sawosz, Ewa; Chwalibog, André; Mitura, Katarzyna; Mitura, Stanisław; Szeliga, Jacek; Niemiec, Tomasz; Rupiewicz, Marlena; Grodzik, Marta; Sokołowska, Aleksandra

2011-09-01

Currently, medicine intensively searches for methods to transport drugs to a target (sick) point within the body. The objective of the present investigation was to evaluate morphological characteristics of the assembles of silver or diamond nanoparticles with Salmonella Enteritidis (G-) or Listeria monocytogenes (G+), to reveal possibilities of constructing nanoparticle-bacteria vehicles. Diamond nanoparticles (nano-D) were produced by the detonation method. Hydrocolloids of silver nanoparticles (nano-Ag) were produced by electric non-explosive patented method. Hydrocolloids of nanoparticles (200 microl) were added to bacteria suspension (200 microl) in the following order: nano-D + Salmonella E.; nano-D + Listeria monocytogenes; nano-Ag + Salmonella E; nano-Ag + Listeria monocytogenes. Samples were inspected by transmission electron microscopy. Visualisation of nanoparticles and bacteria interaction showed harmful effects of both nanoparticles on bacteria morphology. The most spectacular effect of nano-D were strong links between nano-D packages and the flagella of Salmonella E. Nano-Ag were closely attached to Listeria monocytogenes but not to Salmonella E. There was no evidence of entering nano-Ag inside Listeria monocytogenes but smaller particles were placed inside Salmonella E. The ability of nano-D to attach to the flagella and the ability of nano-Ag to penetrate inside bacteria cells can be utilized to design nano-bacteria vehicles, being carriers for active substances attached to nanoparticles.

Delivery of platinum(IV) drug to subcutaneous tumor and lung metastasis using bradykinin-potentiating peptide-decorated chitosan nanoparticles.

PubMed

Wang, Xin; Yang, Chenchen; Zhang, Yajun; Zhen, Xu; Wu, Wei; Jiang, Xiqun

2014-08-01

Selectively activating tumor vessels to increase drug delivery and reduce interstitial fluid pressure of tumors is actively pursued. Here we developed a vasoactive peptide-decorated chitosan nanoparticles for enhancing drug accumulation and penetration in subcutaneous tumor and lung metastasis. The vasoactive peptide used here is bradykinin-potentiating peptide (BPP) containing 9 amino acid residues and the drug is bioreductively sensitive platinum(IV) compound which becomes cisplatin in intracellular reductive environments. Both peptide and drug are covalently linked with chitosan nanoparticles with a diameter of 120 nm. We demonstrate that BPP-decorated chitosan nanoparticles increase the tumorous vascular permeability and reduce the interstitial fluid pressure of tumor simultaneously, both of which improve the penetration of nanoparticles in tumor tissues. The in vivo biodistribution and tumor inhibition examinations demonstrate that the BPP-decorated nanoparticle formulation has more superior efficacy in enhancing drug accumulation in tumor, restraining tumor growth and prolonging the lifetime of tumor-bearing mice than free drug and non-decorated nanoparticle formulation. Meanwhile, the drug accumulation in the lung with metastasis reaches 17% and 20% injected dose per gram of lung for the chitosan nanoparticles without and with BPP decoration, respectively, which is 10-fold larger than that of free cisplatin. The examination of lung metastasis inhibition further indicates that BPP-decorated chitosan nanoparticle formulations can more effectively inhibit lung metastasis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chloride (Cl-) ion-mediated shape control of palladium nanoparticles

NASA Astrophysics Data System (ADS)

Nalajala, Naresh; Chakraborty, Arup; Bera, Bapi; Neergat, Manoj

2016-02-01

The shape control of Pd nanoparticles is investigated using chloride (Cl-) ions as capping agents in an aqueous medium in the temperature range of 60-100 °C. With weakly adsorbing and strongly etching Cl- ions, oxygen plays a crucial role in shape control. The experimental factors considered are the concentration of the capping agents, reaction time and reaction atmosphere. Thus, Pd nanoparticles of various shapes with high selectivity can be synthesized. Moreover, the removal of Cl- ions from the nanoparticle surface is easier than that of Br- ions (moderately adsorbing and etching) and I- ions (strongly adsorbing and weakly etching). The cleaned Cl- ion-mediated shape-controlled Pd nanoparticles are electrochemically characterized and the order of the half-wave potential of the oxygen reduction reaction in oxygen-saturated 0.1 M HClO4 solution is of the same order as that observed with single-crystal Pd surfaces.

Design of five-layer gold nanoparticles self-assembled in a liquid open tubular column for ultrasensitive nano-LC-MS/MS proteomic analysis of 80 living cells.

PubMed

Shao, Xi; Zhang, Xiangmin

2017-04-01

In this work, for the first time, a liquid open tubular column modified by five-layer gold nanoparticles and linked with C 18 (GNPs@C 18 ) was designed and fabricated for nano-LC-MS/MS analysis of 80 living cells. Sixty nanometer gold nanoparticles were self-assembled layer by layer on the inner wall of a 20 μm id fused-silica capillary. C 18 was then linked on the gold nanoparticles to make the liquid open tubular column show hydrophobic character. Enough loading capacities for analysis of 80 living cells, ∼100 fmol for pk-10 and ∼30 fmol for insulin, were obtained with the 2 m × 20 μm id five-layer GNPs@C 18 open tubular column. The open tubular column was used in an online pretreatment and direct nano-LC-MS/MS analysis system to analyze 80 living HepG2 cells. In total, 650 proteins were identified in triplicate runs. The subcellular localization of the identified proteins showed that our system had no bias toward different cellular compartments. Protein copy number per cell of the identified proteins showed that the detection limit could reach 50 zmol and the abundance of the identified proteins could cover a dynamic range of 6 orders. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation on hemolytic effect of poly(lactic co-glycolic) acid nanoparticles synthesized using continuous flow and batch processes

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

Libi, Sumit; Calenic, Bogdan; Astete, Carlos E.

Abstract With the increasing interest in polymeric nanoparticles for biomedical applications, there is a need for continuous flow methodologies that allow for the precise control of nanoparticle synthesis. Poly(lactide-co-glycolic) acid (PLGA) nanoparticles with diameters of 220–250 nm were synthesized using a lab-on-a-chip, exploiting the precise flow control offered by a millifluidic platform. The association and the effect of PLGA nanoparticles on red blood cells (RBCs) were compared for fluorescent PLGA nanoparticles made by this novel continuous flow process using a millifluidic chip and smaller PLGA nanoparticles made by a batch method. Results indicated that all PLGA nanoparticles studied, independent ofmore » the synthesis method and size, adhered to the surface of RBCs but had no significant hemolytic effect at concentrations lower than 10 mg/ml.« less

Design of water-repellant coating using dual scale size of hybrid silica nanoparticles on polymer surface

NASA Astrophysics Data System (ADS)

Conti, J.; De Coninck, J.; Ghazzal, M. N.

2018-04-01

The dual-scale size of the silica nanoparticles is commonly aimed at producing dual-scale roughness, also called hierarchical roughness (Lotus effect). In this study, we describe a method to build a stable water-repellant coating with controlled roughness. Hybrid silica nanoparticles are self-assembled over a polymeric surface by alternating consecutive layers. Each one uses homogenously distributed silica nanoparticles of a particular size. The effect of the nanoparticle size of the first layer on the final roughness of the coating is studied. The first layer enables to adjust the distance between the silica nanoparticles of the upper layer, leading to a tuneable and controlled final roughness. An optimal size nanoparticle has been found for higher water-repellency. Furthermore, the stability of the coating on polymeric surface (Polycarbonate substrate) is ensured by photopolymerization of hybridized silica nanoparticles using Vinyl functional groups.

PEGylated PLGA-based nanoparticles targeting M cells for oral vaccination.

PubMed

Garinot, Marie; Fiévez, Virginie; Pourcelle, Vincent; Stoffelbach, François; des Rieux, Anne; Plapied, Laurence; Theate, Ivan; Freichels, Hélène; Jérôme, Christine; Marchand-Brynaert, Jacqueline; Schneider, Yves-Jacques; Préat, Véronique

2007-07-31

To improve the efficiency of orally delivered vaccines, PEGylated PLGA-based nanoparticles displaying RGD molecules at their surface were designed to target human M cells. RGD grafting was performed by an original method called "photografting" which covalently linked RGD peptides mainly on the PEG moiety of the PCL-PEG, included in the formulation. First, three non-targeted formulations with size and zeta potential adapted to M cell uptake and stable in gastro-intestinal fluids, were developed. Their transport by an in vitro model of the human Follicle associated epithelium (co-cultures) was largely increased as compared to mono-cultures (Caco-2 cells). RGD-labelling of nanoparticles significantly increased their transport by co-cultures, due to interactions between the RGD ligand and the beta(1) intregrins detected at the apical surface of co-cultures. In vivo studies demonstrated that RGD-labelled nanoparticles particularly concentrated in M cells. Finally, ovalbumin-loaded nanoparticles were orally administrated to mice and induced an IgG response, attesting antigen ability to elicit an immune response after oral delivery.

In vitro evaluation of paclitaxel loaded amorphous chitin nanoparticles for colon cancer drug delivery.

PubMed

Smitha, K T; Anitha, A; Furuike, T; Tamura, H; Nair, Shantikumar V; Jayakumar, R

2013-04-01

Chitin and its derivatives have been widely used in drug delivery applications due to its biocompatible, biodegradable and non-toxic nature. In this study, we have developed amorphous chitin nanoparticles (150±50 nm) and evaluated its potential as a drug delivery system. Paclitaxel (PTX), a major chemotherapeutic agent was loaded into amorphous chitin nanoparticles (AC NPs) through ionic cross-linking reaction using TPP. The prepared PTX loaded AC NPs had an average diameter of 200±50 nm. Physico-chemical characterization of the prepared nanoparticles was carried out. These nanoparticles were proven to be hemocompatible and in vitro drug release studies showed a sustained release of PTX. Cellular internalization of the NPs was confirmed by fluorescent microscopy as well as by flow cytometry. Anticancer activity studies proved the toxicity of PTX-AC NPs toward colon cancer cells. These preliminary results indicate the potential of PTX-AC NPs in colon cancer drug delivery. Copyright © 2012 Elsevier B.V. All rights reserved.

Competition Between Extinction and Enhancement in Surface Enhanced Raman Spectroscopy.

PubMed

van Dijk, Thomas; Sivapalan, Sean T; Devetter, Brent M; Yang, Timothy K; Schulmerich, Matthew V; Murphy, Catherine J; Bhargava, Rohit; Carney, P Scott

2013-04-04

Conjugated metallic nanoparticles are a promising means to achieve ultrasensitive and multiplexed sensing in intact three-dimensional samples, especially for biological applications, via surface enhanced Raman scattering (SERS). We show that enhancement and extinction are linked and compete in a collection of metallic nanoparticles. Counterintuitively, the Raman signal vanishes when nanoparticles are excited at their plasmon resonance, while increasing nanoparticle concentrations at off-resonance excitation sometimes leads to decreased signal. We develop an effective medium theory that explains both phenomena. Optimal choices of excitation wavelength, individual particle enhancement factor and concentrations are indicated. The same processes which give rise to enhancement also lead to increased extinction of both the illumination and the Raman scattered light. Nanoparticles attenuate the incident field (blue) and at the same time provide local enhancement for SERS. Likewise the radiation of the Raman-scattered field (green) is enhanced by the near-by sphere but extinguished by the rest of the spheres in the suspension on propagation.

Size control in the synthesis of 1-6 nm gold nanoparticles via solvent-controlled nucleation.

PubMed

Song, Jieun; Kim, Dukhan; Lee, Dongil

2011-11-15

We report a facile synthetic route for size-controlled preparation of gold nanoparticles. Nearly monodisperse gold nanoparticles with core diameters of 1-6 nm were obtained by reducing AuP(Phenyl)(3)Cl with tert-butylamine borane in the presence of dodecanethiol in the solvent mixture of benzene and CHCl(3). Mechanism studies have shown that the size control is achieved by the solvent-controlled nucleation in which the nuclei concentration increases with increasing the fraction of CHCl(3), leading to smaller particles. It was also found that, following the solvent-controlled nucleation, particle growth occurs via ligand replacement of PPh(3) on the nuclei by Au(I)thiolate generated by the digestive etching of small particles. This synthetic strategy was successfully demonstrated with other alkanethiols of different chain length with which size-controlled, monodisperse gold nanoparticles were prepared in remarkable yield without requiring any postsynthesis treatments.

Fracture-induced mechanophore activation and solvent healing in poly(methyl methacrylate)

NASA Astrophysics Data System (ADS)

Celestine, Asha-Dee N.

Damage detection is a highly desirable functionality in engineering materials. The potential of using mechanophores, stress-sensitive molecules, as material stress sensors has been established through tensile, compressive and shear tests. Spiropyran (SP) has been the chosen mechanophore and this molecule undergoes a ring opening reaction (activation) upon the application of mechanical stress. This activation is accompanied by a change in color and fluorescence as the colorless SP is converted to the highly colored merocyanine (MC) form. One requirement for SP activation in bulk polymers is large scale plastic deformation. In order to induce this plastic deformation during fracture testing of SP-linked brittle polymers such as poly(methyl methacrylate) (PMMA), rubber nanoparticles can be incorporated into the matrix material. These nanoparticles facilitate the increased shear yielding necessary for SP activation during mechanical testing. Cross-linked SP-PMMA, containing 7.3 wt% rubber nanoparticles is synthesized via a free radical polymerization. Specimens of this material are fabricated for Single Edge Notch Tension (SENT) testing. The rubber toughened SP-PMMA specimens are first prestretched to approximately 35% axial strain to align the spiropyran molecules in the direction of applied force and thus increase the likelihood of fracture-induced activation. After prestretching the specimens are pre-notched and irradiated with 532 nm wavelength light to revert the colored merocyanine to the colorless spiropyran form. Specimens are then fracture tested to failure using the SENT test. The evolution of mechanophore activation is monitored via in situ fluorescence imaging and inspection of the specimens after testing. Activation of the SP is observed ahead of the crack tip and along the propagated crack. Also, the degree of activation is found to increase with crack growth and the size of the activation zone is linearly correlated to the size of the plastic zone ahead of the crack tip. Control specimens in which the mechanophore is absent or tethered in positions in which no mechanochemical activation is expected are also tested and exhibit no change in color or fluorescence intensity with crack propagation. The relationship between fracture-induced mechanophore activation in rubber toughened SP-PMMA and the strain and stress ahead of the propagating crack is also studied. SP activation is again detected and quantified by in situ fluorescence imaging. Digital Image Correlation (DIC) is used to measure the strain ahead of the crack tip. The corresponding stress is generated through the use of the Hutchinson-Rice-Rosengren (HRR) singularity field equations. Mechanophore activation ahead of the crack tip is shown to follow a power law distribution that is closely aligned with strain. The potential of SP as a damage sensor is explored further by incorporating the spiropyran into the core of rubber nanoparticles. SP-linked rubber nanoparticles are synthesized using a seeded emulsion polymerization process and incorporated into cross-linked PMMA at a concentration of 5 wt%. Cylindrical specimens are torsion tested and the activation of the SP within the nanoparticles is monitored via full field fluorescence imaging. SP activation within the core is shown to increase with shear strain. Autonomous damage repair in PMMA is also investigated. The first demonstration of fully autonomous self-healing in PMMA is achieved through the use of solvent microcapsules. Solvent microcapsules with a PMMA-anisole liquid core are prepared and embedded within a linear PMMA matrix. Specimens of the microcapsule-loaded material are then fabricated for Double Cleavage Drilled Compression (DCDC) fracture testing. The DCDC specimens, containing increasing concentrations of solvent microcapsules, are tested and then allowed to heal for a fixed period of time before a second DCDC test. The healing efficiency of each material system is evaluated based on the recovery of fracture toughness and is shown to be dependent on healing time and microcapsule concentration. (Abstract shortened by UMI.).

An experimental investigation of localised surface plasmon resonance (LSPR) for Cu nanoparticles depending as a function of laser pulse number in Pulsed Laser Deposition

NASA Astrophysics Data System (ADS)

Gezgin, Serap Yiǧit; Kepceoǧlu, Abdullah; Kılıç, Hamdi Şükür

2017-02-01

Copper is a low cost metal and its nanoparticles have a unique optical properties such as LSPR. The location of LSPR wavelength can be tuned by controlling nanoparticles sizes and size distributions of nanoparticles, shapes and interparticle distances. This morphological changes are provided by controlling system parameters in PLD. For this work, 48000 and 36000 laser pulses from Nd:YAG laser were applied to produce Cu nanoparticle thin films. These thin films were characterised by performing UV-VIS absorption spectroscopy, Atomic Force Microscopy (AFM) analysis. When the number of laser pulse decreases, the size of Cu nanoparticles and the number of nanoparticles arriving on the substrate are reduced, and LSPR peak of thin films are red shifted depending on the geometrical shapes of the Cu nanoparticles. We have driven a conclusion in this work that LSPR properties of Cu nanoparticles can be tuned by proposed method.

Magnetic iron oxide nanoparticles (MIONs) cross-linked natural polymer-based hybrid gel beads: Controlled nano anti-TB drug delivery application.

PubMed

Kesavan, Mookkandi Palsamy; Ayyanaar, Srinivasan; Vijayakumar, Vijayaparthasarathi; Dhaveethu Raja, Jeyaraj; Annaraj, Jamespandi; Sakthipandi, Kathiresan; Rajesh, Jegathalaprathaban

2018-04-01

The nanosized rifampicin (RIF) has been prepared to increase the solubility in aqueous solution, which leads to remarkable enhancement of its bioavailability and their convenient delivery system studied by newly produced nontoxic, biodegradable magnetic iron oxide nanoparticles (MIONs) cross-linked polyethylene glycol hybrid chitosan (mCS-PEG) gel beads. The functionalization of both nano RIF and mCS-PEG gel beads were studied using various spectroscopic and microscopic techniques. The size of prepared nano RIF was found to be 70.20 ± 3.50 nm. The mechanical stability and swelling ratio of the magnetic gel beads increased by the addition of PEG with a maximum swelling ratio of 38.67 ± 0.29 g/g. Interestingly, this magnetic gel bead has dual responsive assets in the nano drug delivery application (pH and the magnetic field). As we expected, magnetic gel beads show higher nano drug releasing efficacy at acidic medium (pH = 5.0) with maximum efficiency of 71.00 ± 0.87%. This efficacy may also be tuned by altering the external magnetic field and the weight percentage (wt%) of PEG. These results suggest that such a dual responsive magnetic gel beads can be used as a potential system in the nano drug delivery applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1039-1050, 2018. © 2017 Wiley Periodicals, Inc.

Design of a temperature measurement and feedback control system based on an improved magnetic nanoparticle thermometer

NASA Astrophysics Data System (ADS)

Du, Zhongzhou; Sun, Yi; Liu, Jie; Su, Rijian; Yang, Ming; Li, Nana; Gan, Yong; Ye, Na

2018-04-01

Magnetic fluid hyperthermia, as a novel cancer treatment, requires precise temperature control at 315 K-319 K (42 °C-46 °C). However, the traditional temperature measurement method cannot obtain the real-time temperature in vivo, resulting in a lack of temperature feedback during the heating process. In this study, the feasibility of temperature measurement and feedback control using magnetic nanoparticles is proposed and demonstrated. This technique could be applied in hyperthermia. Specifically, the triangular-wave temperature measurement method is improved by reconstructing the original magnetization response of magnetic nanoparticles based on a digital phase-sensitive detection algorithm. The standard deviation of the temperature in the magnetic nanoparticle thermometer is about 0.1256 K. In experiments, the temperature fluctuation of the temperature measurement and feedback control system using magnetic nanoparticles is less than 0.5 K at the expected temperature of 315 K. This shows the feasibility of the temperature measurement method for temperature control. The method provides a new solution for temperature measurement and feedback control in hyperthermia.

Nanoparticle Immobilization for Controllable Experiments in Liquid-Cell Transmission Electron Microscopy.

PubMed

Robertson, Alex W; Zhu, Guomin; Mehdi, B Layla; Jacobs, Robert M J; De Yoreo, James; Browning, Nigel D

2018-06-22

We demonstrate that silanization can control the adhesion of nanostructures to the SiN windows compatible with liquid-cell transmission electron microscopy (LC-TEM). Formation of an (3-aminopropyl)triethoxysilane (APTES) self-assembled monolayer on a SiN window, producing a surface decorated with amino groups, permits strong adhesion of Au nanoparticles to the window. Many of these nanoparticles remain static, undergoing minimal translation or rotation during LC-TEM up to high electron beam current densities due to the strong interaction between the APTES amino group and Au. We then use this technique to perform a direct comparative LC-TEM study on the behavior of ligand and nonligand-coated Au nanoparticles in a Au growth solution. While the ligand coated nanoparticles remain consistent even under high electron beam current densities, the naked nanoparticles acted as sites for secondary Au nucleation. These nucleated particles decorated the parent nanoparticle surface, forming consecutive monolayer assemblies of ∼2 nm diameter nanoparticles, which sinter into the parent particle when the electron beam was shut off. This method for facile immobilization of nanostructures for LC-TEM study will permit more sophisticated and controlled in situ experiments into the properties of solid-liquid interfaces in the future.

Biophysical characterization of hydrogel-core, lipid-shell nanoparticles (nanolipogels) for HIV chemoprophylaxis

NASA Astrophysics Data System (ADS)

Mahadevan, Reena

Nanoparticles are emerging as versatile vehicles for drug delivery, providing targeting, protection, and controlled-release capabilities to encapsulated cargo. Polymeric nanoparticles made from poly(lactide-co-glycolide) (PLGA) are biodegradable, exhibit tunable drug release, and have encapsulated a wide variety of biological agents. However, PLGA nanoparticles are relatively inefficient at encapsulating small-molecule hydrophilic drugs. Liposomes encapsulate greater amounts of hydrophilic agents and demonstrate good cellular affinity; however, they lack controlled-release functionality. Hydrogel-core lipid-shell nanoparticles, or nanolipogels, combine the controlled-release capability of polymeric nanocarriers with the hydrophilic and cellular affinity of liposomes into a single drug delivery vehicle. This study establishes a facile, reproducible synthetic protocol for nanolipogels and evaluates hydrogel swelling as a mechanism for release of the small hydrophilic antiretroviral azidothymidine from nanolipogels.

Controlled green synthesis of silver nanoparticles by Allium cepa and Musa acuminata with strong antimicrobial activity

NASA Astrophysics Data System (ADS)

Sahni, Geetika; Panwar, Amit; Kaur, Balpreet

2015-02-01

A controlled "green synthesis" approach to synthesize silver nanoparticles by Allium cepa and Musa acuminata plant extract has been reported. The effect of different process parameters, such as pH, temperature and time, on synthesis of Ag nanoparticles from plant extracts has been highlighted. The work reports an easy approach to control the kinetics of interaction of metal ions with reducing agents, stabilized by ammonia to achieve sub-10 nm particles with narrow size distribution. The nanoparticles have been characterized by UV-Visible spectra and TEM analysis. Excellent antimicrobial activity at extremely low concentration of the nanoparticles was observed against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Fusarium oxysporum which may allow their exploitation as a new generation nanoproduct in biomedical and agricultural applications.

Determining the Effect of Aluminum Oxide Nanoparticles on the Aggregation of Amyloid-Beta in Transgenic Caenorhabditis elegans

NASA Astrophysics Data System (ADS)

Patel, Suhag; Matticks, John; Howell, Carina

2014-03-01

The cause of Alzheimer's disease has been linked partially to genetic factors but the predicted environmental components have yet to be determined. In Alzheimer's, accumulation of amyloid-beta protein in the brain forms plaques resulting in neurodegeneration and loss of mental functions. It has been postulated that aluminum influences the aggregation of amyloid-beta. To test this hypothesis, transgenic Caenorhabditis elegans, CL2120, was used as a model organism to observe neurodegeneration in nematodes exposed to aluminum oxide nanoparticles. Behavioral testing, fluorescent staining, and fluorescence microscopy were used to test the effects of aggregation of amyloid-beta in the nervous systems of effected nematodes exposed to aluminum oxide nanoparticles. Energy-dispersive x-ray spectroscopy was used to quantify the total concentration of aluminum oxide that the worms were exposed to during the experiment. Exposure of transgenic and wild type worms to a concentration of 4 mg mL-1 aluminum oxide showed a decrease in the sinusoidal motion, as well as an infirmity of transgenic worms when compared to control worms. These results support the hypothesis that aluminum may play a role in neurodegeneration in C. elegans, and may influence and increase the progression of Alzheimer's disease. This work was supported by National Science Foundation grants DUE-1058829, DMR-0923047 DUE-0806660 and Lock Haven FPDC grants.

Inhibition of bacterial growth by iron oxide nanoparticles with and without attached drug: Have we conquered the antibiotic resistance problem?

NASA Astrophysics Data System (ADS)

Armijo, Leisha M.; Jain, Priyanka; Malagodi, Angelina; Fornelli, F. Zuly; Hayat, Allison; Rivera, Antonio C.; French, Michael; Smyth, Hugh D. C.; Osiński, Marek

2015-03-01

Pseudomonas aeruginosa is among the top three leading causative opportunistic human pathogens, possessing one of the largest bacterial genomes and an exceptionally large proportion of regulatory genes therein. It has been known for more than a decade that the size and complexity of the P. aeruginosa genome is responsible for the adaptability and resilience of the bacteria to include its ability to resist many disinfectants and antibiotics. We have investigated the susceptibility of P. aeruginosa bacterial biofilms to iron oxide (magnetite) nanoparticles (NPs) with and without attached drug (tobramycin). We also characterized the susceptibility of zero-valent iron NPs, which are known to inactivate microbes. The particles, having an average diameter of 16 nm were capped with natural alginate, thus doubling the hydrodynamic size. Nanoparticle-drug conjugates were produced via cross-linking drug and alginate functional groups. Drug conjugates were investigated in the interest of determining dosage, during these dosage-curve experiments, NPs unbound to drug were tested in cultures as a negative control. Surprisingly, we found that the iron oxide NPs inhibited bacterial growth, and thus, biofilm formation without the addition of antibiotic drug. The inhibitory dosages of iron oxide NPs were investigated and the minimum inhibitory concentrations are presented. These findings suggest that NP-drug conjugates may overcome the antibiotic drug resistance common in P. aeruginosa infections.

Size-Selective Synthesis and Stabilization of Small Silver Nanoparticles on TiO 2 Partially Masked by SiO 2

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

Bo, Zhenyu; Eaton, Todd R.; Gallagher, James R.

Controlling metal nanoparticle size is one of the principle challenges in developing new supported catalysts. Typical methods where a metal salt is deposited and reduced can result in a polydisperse mixture of metal nanoparticles, especially at higher loading. Polydispersity can exacerbate the already significant challenge of controlling sintering at high temperatures, which decreases catalytic surface area. Here, we demonstrate the size-selective photoreduction of Ag nanoparticles on TiO2 whose surface has been partially masked with a thin SiO2 layer. To synthesize this layered oxide material, TiO2 particles are grafted with tert-butylcalix[4]arene molecular templates (~2 nm in diameter) at surface densities ofmore » 0.05–0.17 templates.nm–2, overcoated with ~2 nm of SiO2 through repeated condensation cycles of limiting amounts of tetraethoxysilane (TEOS), and the templates are removed oxidatively. Ag photodeposition results in uniform nanoparticle diameters ≤ 3.5 nm (by transmission electron microscopy (TEM)) on the partially masked TiO2, whereas Ag nanoparticles deposited on the unmodified TiO2 are larger and more polydisperse (4.7 ± 2.7 nm by TEM). Furthermore, Ag nanoparticles on the partially masked TiO2 do not sinter after heating at 450 °C for 3 h, while nanoparticles on the control surfaces sinter and grow by at least 30%, as is typical. Overall, this new synthesis approach controls metal nanoparticle dispersion and enhances thermal stability, and this facile synthesis procedure is generalizable to other TiO2-supported nanoparticles and sizes and may find use in the synthesis of new catalytic materials.« less

Probing the effect of charge transfer enhancement in off resonance mode SERS via conjugation of the probe dye between silver nanoparticles and metal substrates.

PubMed

Selvakannan, Pr; Ramanathan, Rajesh; Plowman, Blake J; Sabri, Ylias M; Daima, Hemant K; O'Mullane, Anthony P; Bansal, Vipul; Bhargava, Suresh K

2013-08-21

The charge transfer-mediated surface enhanced Raman scattering (SERS) of crystal violet (CV) molecules that were chemically conjugated between partially polarized silver nanoparticles and optically smooth gold and silver substrates has been studied under off-resonant conditions. Tyrosine molecules were used as a reducing agent to convert silver ions into silver nanoparticles where oxidised tyrosine caps the silver nanoparticle surface with its semiquinone group. This binding through the quinone group facilitates charge transfer and results in partially oxidised silver. This establishes a chemical link between the silver nanoparticles and the CV molecules, where the positively charged central carbon of CV molecules can bind to the terminal carboxylate anion of the oxidised tyrosine molecules. After drop casting Ag nanoparticles bound with CV molecules it was found that the free terminal amine groups tend to bind with the underlying substrates. Significantly, only those CV molecules that were chemically conjugated between the partially polarised silver nanoparticles and the underlying gold or silver substrates were found to show SERS under off-resonant conditions. The importance of partial charge transfer at the nanoparticle/capping agent interface and the resultant conjugation of CV molecules to off resonant SERS effects was confirmed by using gold nanoparticles prepared in a similar manner. In this case the capping agent binds to the nanoparticle through the amine group which does not facilitate charge transfer from the gold nanoparticle and under these conditions SERS enhancement in the sandwich configuration was not observed.

Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

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

Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani

2015-09-25

We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between sphericalmore » and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.« less

Peptide-directed self-assembly of functionalized polymeric nanoparticles. Part II: effects of nanoparticle composition on assembly behavior and multiple drug loading ability.

PubMed

Xiang, Xu; Ding, Xiaochu; Moser, Trevor; Gao, Qi; Shokuhfar, Tolou; Heiden, Patricia A

2015-04-01

Peptide-functionalized polymeric nanoparticles were designed and self-assembled into continuous nanoparticle fibers and three-dimensional scaffolds via ionic complementary peptide interaction. Different nanoparticle compositions can be designed to be appropriate for each desired drug, so that the release of each drug is individually controlled and the simultaneous sustainable release of multiple drugs is achieved in a single scaffold. A self-assembled scaffold membrane was incubated with NIH3T3 fibroblast cells in a culture dish that demonstrated non-toxicity and non-inhibition on cell proliferation. This type of nanoparticle scaffold combines the advantages of peptide self-assembly and the versatility of polymeric nanoparticle controlled release systems for tissue engineering. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of controlled radical polymerization (CRP) in the design of functional biomedical architectures

NASA Astrophysics Data System (ADS)

Siegwart, Daniel John

In this thesis, atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization were utilized in the design of synthetic polymers to create tissue engineering scaffolds and drug delivery systems with improved control over structure and functionality. Thermo-sensitive injectable hydrogels based on poly(NIPAAm) with degradable ester units within the polymer backbone and at the cross-linking sites were prepared using ATRP and RAFT. Solvent induced morphologies of poly(methyl methacrylate-b-ethylene oxide-b-methyl methacrylate) triblock copolymers synthesized by ATRP were described. A micellar structure, composed of a hydrophobic PMMA core and a PEO shell was constructed for delivery of hydrophobic drugs. ATRP was carried out in inverse miniemulsion to prepare well defined functional nanogels that were capable of entrapping and releasing various molecules (Doxorubicin, carbohydrate-based drugs, fluorophores, and gold nanoparticles). The results demonstrated that nanogels prepared by ATRP in inverse miniemulsion could be internalized into cells via clathrin-mediated endocytosis. Nanogels functionalized with integrin-binding peptides increased cellular uptake. A process called Atom Transfer Radical Coupling (ATRC) was also described, which illustrated the power of functionality in ATRP. Finally, linear polymers and cross-linked nanogels were synthesized by ATRP and functionalized with biotin, pyrene, and peptide sequences, tying together the overall themes of structural control and functionality.

Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass

USDA-ARS?s Scientific Manuscript database

Heteroaggregation with indigenous particles is an important process controlling the mobility of engineered nanomaterials in the environment. We studied heteroaggregation of cerium oxide nanoparticles (n-CeO2), which are widely used commercially, with nanoparticles of pyrogenic carbonaceous material ...

A pure magnetite hydrogel: synthesis, properties and possible applications.

PubMed

Anastasova, Elizaveta I; Ivanovski, Vladimir; Fakhardo, Anna F; Lepeshkin, Artem I; Omar, Suheir; Drozdov, Andrey S; Vinogradov, Vladimir V

2017-11-22

A magnetite-only hydrogel was prepared for the first time by weak base mediated gelation of stable magnetite hydrosols at room temperature. The hydrogel consists of 10 nm magnetite nanoparticles linked by interparticle Fe-O-Fe bonds and has the appearance of a dark-brown viscous thixotropic material. The water content in the hydrogel could be up to 93.6% by mass while volume fraction reaches 99%. The material shows excellent biocompatibility and minor cytotoxic effects at concentrations up to 207 μg mL -1 . The gel shows excellent sorption capacity for heavy metal adsorption such as chrome and lead ions, which is 225% more than the adsorption capacity of magnetite nanoparticles. Due to thixotropic nature, the gel demonstrates mechanical stimuli-responsive release behavior with up to 98% release triggered by ultrasound irradiation. The material shows superparamagnetic behavior with a coercivity of 65 emu g -1 at 6000 Oe. The magnetite gels prepared could be used for the production of magnetite aerogels, magnetic drug delivery systems with controlled release and highly efficient sorbents for hydrometallurgy.

Optimization for rapid synthesis of silver nanoparticles and its effect on phytopathogenic fungi

NASA Astrophysics Data System (ADS)

Krishnaraj, C.; Ramachandran, R.; Mohan, K.; Kalaichelvan, P. T.

In this present study, silver nanoparticles were synthesized by green chemistry approach using Acalypha indica leaf extract as reducing agents. The reaction medium employed in the synthesis process was optimized to attain better yield, controlled size and stability. Further, the biosynthesized silver nanoparticles were conformed through UV-vis spectrum, XRD and HR-TEM analyses. Different concentration of silver nanoparticles were tested to know the inhibitory effect of fungal plant pathogens namely Alternaria alternata, Sclerotinia sclerotiorum, Macrophomina phaseolina, Rhizoctonia solani, Botrytis cinerea and Curvularia lunata. Interestingly, 15 mg concentration of silver nanoparticles showed excellent inhibitory activity against all the tested pathogens. Thus, the obtained results clearly suggest that silver nanoparticles may have important applications in controlling various plant diseases caused by fungi.

Morphological effects on the selectivity of intramolecular versus intermolecular catalytic reaction on Au nanoparticles.

PubMed

Wang, Dan; Sun, Yuanmiao; Sun, Yinghui; Huang, Jing; Liang, Zhiqiang; Li, Shuzhou; Jiang, Lin

2017-06-14

It is hard for metal nanoparticle catalysts to control the selectivity of a catalytic reaction in a simple process. In this work, we obtain active Au nanoparticle catalysts with high selectivity for the hydrogenation reaction of aromatic nitro compounds, by simply employing spine-like Au nanoparticles. The density functional theory (DFT) calculations further elucidate that the morphological effect on thermal selectivity control is an internal key parameter to modulate the nitro hydrogenation process on the surface of Au spines. These results show that controlled morphological effects may play an important role in catalysis reactions of noble metal NPs with high selectivity.

γ-PARCEL: Control of Molecular Release Using γ-Rays.

PubMed

Murayama, Shuhei; Jo, Jun-ichiro; Arai, Kazutaka; Nishikido, Fumihiko; Bakalova, Rumiana; Yamaya, Taiga; Saga, Tsuneo; Kato, Masaru; Aoki, Ichio

2015-12-01

We previously have developed the photoresponsive tetra-gel and nanoparticles for controlling the function of the encapsulated substance by UV irradiation. However, the penetration ability of the UV is not high enough. Here, we developed a radiation-responsive tetra-gel and nanoparticle based on γ-ray-responsive X-shaped polyethylene glycol (PEG) linker with a disulfide bond. The nanoparticle could retain small molecules and biomacromolecules. γ-Rays were used as a trigger signal because of their higher penetrating ability. This allowed a spatiotemporal release and control of the encapsulated substances from the nanoparticle in the deeper region, which is impossible by using light exposure (ultraviolet, visible, and near-infrared).

Redox-Responsive Magnetic Nanoparticle for Targeted Convection-Enhanced Delivery of O6-Benzylguanine to Brain Tumors

PubMed Central

2015-01-01

Resistance to temozolomide (TMZ) based chemotherapy in glioblastoma multiforme (GBM) has been attributed to the upregulation of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT). Inhibition of MGMT using O6-benzylguanine (BG) has shown promise in these patients, but its clinical use is hindered by poor pharmacokinetics that leads to unacceptable toxicity. To improve BG biodistribution and efficacy, we developed superparamagnetic iron oxide nanoparticles (NP) for targeted convection-enhanced delivery (CED) of BG to GBM. The nanoparticles (NPCP-BG-CTX) consist of a magnetic core coated with a redox-responsive, cross-linked, biocompatible chitosan-PEG copolymer surface coating (NPCP). NPCP was modified through covalent attachment of BG and tumor targeting peptide chlorotoxin (CTX). Controlled, localized BG release was achieved under reductive intracellular conditions and NPCP-BG-CTX demonstrated proper trafficking of BG in human GBM cells in vitro. NPCP-BG-CTX treated cells showed a significant reduction in MGMT activity and the potentiation of TMZ toxicity. In vivo, CED of NPCP-BG-CTX produced an excellent volume of distribution (Vd) within the brain of mice bearing orthotopic human primary GBM xenografts. Significantly, concurrent treatment with NPCP-BG-CTX and TMZ showed a 3-fold increase in median overall survival in comparison to NPCP-CTX/TMZ treated and untreated animals. Furthermore, NPCP-BG-CTX mitigated the myelosuppression observed with free BG in wild-type mice when administered concurrently with TMZ. The combination of favorable physicochemical properties, tumor cell specific BG delivery, controlled BG release, and improved in vivo efficacy demonstrates the great potential of these NPs as a treatment option that could lead to improved clinical outcomes. PMID:25247850

Redox-responsive magnetic nanoparticle for targeted convection-enhanced delivery of O6-benzylguanine to brain tumors.

PubMed

Stephen, Zachary R; Kievit, Forrest M; Veiseh, Omid; Chiarelli, Peter A; Fang, Chen; Wang, Kui; Hatzinger, Shelby J; Ellenbogen, Richard G; Silber, John R; Zhang, Miqin

2014-10-28

Resistance to temozolomide (TMZ) based chemotherapy in glioblastoma multiforme (GBM) has been attributed to the upregulation of the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). Inhibition of MGMT using O(6)-benzylguanine (BG) has shown promise in these patients, but its clinical use is hindered by poor pharmacokinetics that leads to unacceptable toxicity. To improve BG biodistribution and efficacy, we developed superparamagnetic iron oxide nanoparticles (NP) for targeted convection-enhanced delivery (CED) of BG to GBM. The nanoparticles (NPCP-BG-CTX) consist of a magnetic core coated with a redox-responsive, cross-linked, biocompatible chitosan-PEG copolymer surface coating (NPCP). NPCP was modified through covalent attachment of BG and tumor targeting peptide chlorotoxin (CTX). Controlled, localized BG release was achieved under reductive intracellular conditions and NPCP-BG-CTX demonstrated proper trafficking of BG in human GBM cells in vitro. NPCP-BG-CTX treated cells showed a significant reduction in MGMT activity and the potentiation of TMZ toxicity. In vivo, CED of NPCP-BG-CTX produced an excellent volume of distribution (Vd) within the brain of mice bearing orthotopic human primary GBM xenografts. Significantly, concurrent treatment with NPCP-BG-CTX and TMZ showed a 3-fold increase in median overall survival in comparison to NPCP-CTX/TMZ treated and untreated animals. Furthermore, NPCP-BG-CTX mitigated the myelosuppression observed with free BG in wild-type mice when administered concurrently with TMZ. The combination of favorable physicochemical properties, tumor cell specific BG delivery, controlled BG release, and improved in vivo efficacy demonstrates the great potential of these NPs as a treatment option that could lead to improved clinical outcomes.

Purchase of Microwave Reactors for Implementation of Small-scale Microwave-accelerated Organic Chemistry Laboratory Program in Undergraduate Curriculum and Synthetic Chemistry Research at HU

DTIC Science & Technology

2015-05-16

synthesis of iron magnetic nanoparticles is being investigated (Appendix A; Scheme IV). In the first step, precursor iron(III) chloride nanoparticles...and other methods. Currently, we are developing a two-step scheme for the synthesis of esters that will require distillation and/or column...recognize the link between them. We are developing for the above purpose, the microwave-assisted, two-step synthesis of high boiling point esters. The

Introducing MINA--The Molecularly Imprinted Nanoparticle Assay.

PubMed

Shutov, Roman V; Guerreiro, Antonio; Moczko, Ewa; de Vargas-Sansalvador, Isabel Perez; Chianella, Iva; Whitcombe, Michael J; Piletsky, Sergey A

2014-03-26

A new ELISA- (enzyme-linked immunosorbent assay)-like assay is demonstrated in which no elements of biological origin are used for molecular recognition or signaling. Composite imprinted nanoparticles that contain a catalytic core and which are synthesized by using a solid-phase approach can simultaneously act as recognition/signaling elements, and be used with minimal modifications to standard assay protocols. This assay provides a new route towards replacement of unstable biomolecules in immunoassays. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Use of Soybean Lecithin in Shape Controlled Synthesis of Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Ayres, Benjamin Robert

The work presented in this dissertation is a composite of experiments in the growth of gold nanoparticles with specific optical properties of interest. The goal is to synthesize these gold nanoparticles using soybean extract for not only shape control, but for propensity as a biocompatible delivery system. The optical properties of these nanoparticles has found great application in coloring glass during the Roman empire and, over the centuries, has grown into its own research field in applications of nanoparticulate materials. Many of the current functions include use in biological systems as biosensors and therapeutic applications, thus making biocompatibility a necessity. Current use of cetyltrimethylammonium bromide leads to rod-shaped gold nanoparticles, however, the stability of these gold nanoparticles does not endure for extended periods of time in aqueous media. In my research, two important components were found to be necessary for stable, anisotropic growth of gold nanoparticles. In the first experiments, it was found that bromide played a key role in shape control. Bromide exchange on the gold atoms led to specific packing of the growing crystals, allowing for two-dimensional growth of gold nanoparticles. It was also discerned that soybean lecithin contained ligands that blocked specific gold facets leading to prismatic gold nanoparticle growth. These gold nanoprisms give a near infrared plasmon absorption similar to that of rod-shaped gold nanoparticles. These gold nanoprisms are discovered to be extremely stable in aqueous media and remain soluble for extended periods of time, far longer than that of gold nanoparticles grown using cetyltrimethylammonium bromide. Since soy lecithin has a plethora of compounds present, it became necessary to discover which compound was responsible for the shape control of the gold nanoprisms in order to optimize the synthesis and allow for a maximum yield of the gold nanoprisms. Many of these components were identified by high performance liquid chromatography and liquid chromatography-mass spectrometry. However, re-spike of these components into growth solutions did not enhance the growth of gold nanoprisms. Upon separating the shapes of the gold nanoparticles using gel electrophoresis, addition of KCN to the separated gold nanoparticles allowed us to extract the culpable ligands for shape control. Analysis of these ligands by mass spectrometry elucidated the identity of PA and upon re-spike of the PA into a growth solution of PC95, the growth of a near-infrared plasmon absorption was seen. The stability of these gold nanoparticles was tested with and without the addition of decane thiol and it was concluded that addition of the thiol allowed for improved stability of the gold nanoparticles towards cyanide. It was determined that at a concentration of 2 μM decanethiol, spherical gold nanoparticles remained stable to cyanide at the expense of the prismatic gold nanoparticles. However, at 5 μM decanethiol, both spherical and prismatic gold nanoparticles retained stability to cyanide in aqueous conditions.

Magnetofluorescent nanocomposites and quantum dots used for optimal application in magnetic fluorescence-linked immunoassay.

PubMed

Tsai, H Y; Li, S Y; Fuh, C Bor

2018-03-01

Magnetofluorescent nanocomposites with optimal magnetic and fluorescent properties were prepared and characterized by combining magnetic nanoparticles (iron oxide@polymethyl methacrylate) with fluorescent nanoparticles (rhodamine 6G@mSiO 2 ). Experimental parameters were optimized to produce nanocomposites with high magnetic susceptibility and fluorescence intensity. The detection of a model biomarker (alpha-fetoprotein) was used to demonstrate the feasibility of applying the magnetofluorescent nanocomposites combined with quantum dots and using magnetic fluorescence-linked immunoassay. The magnetofluorescent nanocomposites enable efficient mixing, fast re-concentration, and nanoparticle quantization for optimal reactions. Biofunctional quantum dots were used to confirm the alpha-fetoprotein (AFP) content in sandwich immunoassay after mixing and washing. The analysis time was only one third that required in ELISA. The detection limit was 0.2 pg mL -1 , and the linear range was 0.68 pg mL -1 -6.8 ng mL -1 . This detection limit is lower, and the linear range is wider than those of ELISA and other methods. The measurements made using the proposed method differed by less than 13% from those obtained using ELISA for four AFP concentrations (0.03, 0.15, 0.75, and 3.75 ng mL -1 ). The proposed method has a considerable potential for biomarker detection in various analytical and biomedical applications. Graphical abstract Magnetofluorescent nanocomposites combined with fluorescent quantum dots were used in magnetic fluorescence-linked immunoassay.

Enzyme nanoparticle fabrication: magnetic nanoparticle synthesis and enzyme immobilization.

PubMed

Johnson, Patrick A; Park, Hee Joon; Driscoll, Ashley J

2011-01-01

Immobilized enzymes are drawing significant attention for potential commercial applications as biocatalysts by reducing operational expenses and by increasing process utilization of the enzymes. Typically, immobilized enzymes have greater thermal and operational stability at various pH values, ionic strengths and are more resistant to denaturation that the soluble native form of the enzyme. Also, immobilized enzymes can be recycled by utilizing the physical or chemical properties of the supporting material. Magnetic nanoparticles provide advantages as the supporting material for immobilized enzymes over competing materials such as: higher surface area that allows for greater enzyme loading, lower mass transfer resistance, less fouling effect, and selective, nonchemical separation from the reaction mixture by an applied a magnetic field. Various surface modifications of magnetic nanoparticles, such as silanization, carbodiimide activation, and PEG or PVA spacing, aid in the binding of single or multienzyme systems to the particles, while cross-linking using glutaraldehyde can also stabilize the attached enzymes.

Genipin-modified gelatin nanocarriers as swelling controlled drug delivery system for in vitro release of cytarabine.

PubMed

Khan, Huda; Shukla, R N; Bajpai, A K

2016-04-01

The aim of the present investigation was to design biocompatible gelatin nanoparticles, capable of releasing the cytarabine drug in a controllable way by regulating the extent of swelling of nanoparticles. In order to achieve the proposed objectives, gelatin (Type A, derived from acid cured tissue) was modified by crosslinking with genipin and nanoparticles of crosslinked gelatin were prepared using single water in oil (W/O) emulsion technique. The nanoparticles were characterized by techniques like FTIR, SEM, TEM, particles size analysis, and surface potential measurements. The nanoparticle chemical architecture was found to influence drug-releasing capacity. The influence of experimental conditions such as pH and simulated physiological fluids as the release medium was also investigated on the release profiles of cytarabine. It is possible to fabricate high-performance materials, by designing of controlled size gelatin nanoparticles with good biocompatible properties along with desired drug release profiles. Copyright © 2015 Elsevier B.V. All rights reserved.

Thrombolysis based on magnetically-controlled surface-functionalized Fe3O4 nanoparticle

PubMed Central

Chang, Ming; Lin, Yu-Hao; Gabayno, Jacque Lynn; Li, Qian; Liu, Xiaojun

2017-01-01

ABSTRACT In this study, the control of magnetic fields to manipulate surface-functionalized Fe3O4 nanoparticles by urokinase coating is investigated for thrombolysis in a microfluidic channel. The urokinase-coated Fe3O4 nanoparticles are characterized using particle size distribution, zeta potential measurement and spectroscopic data. Thrombolytic ratio tests reveal that the efficiency for thrombus cleaning is significantly improved when using magnetically-controlled urokinase-coated Fe3O4 nanoparticles than pure urokinase solution. The average increase in the rate of thrombolysis with the use of urokinase-coated Fe3O4 nanoparticles is about 50%. In vitro thrombolysis test in a microfluidic channel using the coated nanoparticles shows nearly complete removal of thrombus, a result that can be attributed to the clot busting effect of the urokinase as it inhibits the possible formation of blood bolus during the magnetically-activated microablation process. The experiment further demonstrates that a thrombus mass of 10.32 mg in the microchannel is fully removed in about 180 s. PMID:27689864

Application of poly(epsilon-caprolactone) nanoparticles containing atrazine herbicide as an alternative technique to control weeds and reduce damage to the environment.

PubMed

Pereira, Anderson E S; Grillo, Renato; Mello, Nathalie F S; Rosa, Andre H; Fraceto, Leonardo F

2014-03-15

Nanoparticles of poly(epsilon-caprolactone) containing the herbicide atrazine were prepared, characterized, and evaluated in terms of their herbicidal activity and genotoxicity. The stability of the nanoparticles was evaluated over a period of three months, considering the variables: size, polydispersion index, pH, and encapsulation efficiency. Tests on plants were performed with target (Brassica sp.) and non-target (Zea mays) organisms, and the nanoparticle formulations were shown to be effective for the control of the target species. Experiments using soil columns revealed that the use of nanoparticles reduced the mobility of atrazine in the soil. Application of the Allium cepa chromosome aberration assay demonstrated that the nanoparticle systems were able to reduce the genotoxicity of the herbicide. The formulations developed offer a useful means of controlling agricultural weeds, while at the same time reducing the risk of harm to the environment and human health. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigation of follicular and non-follicular pathways for polyarginine and oleic acid modified nanoparticles

PubMed Central

Hayden, Patrick; Singh, Mandip

2013-01-01

Purpose The aim of the current study was to investigate the percutaneous permeation pathways of cell penetrating peptide modified lipid nanoparticles and oleic acid modified polymeric nanoparticles. Methods Confocal microscopy was performed on skin cultures (EpiDermFT™) for modified and un-modified nanoparticles. Differential stripping was performed following in vitro skin permeation of Ibuprofen (Ibu) encapsulated nanoparticles to estimate Ibu levels in different skin layers and receiver compartment. The hair follicles (HF) were blocked and in vitro skin permeation of nanoparticles was then compared with unblocked HF. The surface modified nanoparticles were investigated for response on allergic contact dermatitis (ACD). Results Surface modified nanoparticles showed a significant higher (p < 0.05) in fluorescence in EpiDermFT™ cultures compared to controls. The HF play less than 5% role in total nanoparticle permeation into the skin. The Ibu levels were significantly high (p<0.05) for surface modified nanoparticles compared to controls. The Ibu levels in skin and receiver compartment were not significantly different when HF were open or closed. Modified nanoparticles showed significant improvement in treatment of ACD compared to solution. Conclusions Our studies demonstrate that increased skin permeation of surface modified nanoparticles is not only dependent on a follicular pathway but also occur through non-follicular pathway(s). PMID:23187866

Freezing polystyrene-b-poly(2-vinylpyridine) micelle nanoparticles with different nanostructures and sizes.

PubMed

Fan, Hailong; Jin, Zhaoxia

2014-04-28

Herein we report how to control the nanostructures and sizes of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) nanoparticles via manipulating freezing in solvent-exchange. By characterizing and analyzing the distinct structural features of the obtained nanoparticles, we recognized that micelle self-assembly happens in the precipitation of PS-b-P2VP when water is added into the block copolymer (BCP) solution. Solvent properties significantly influence micelle types that are vesicles in acetone/H2O and spherical micelles in tetrahydrofuran/H2O, respectively, thus further inducing different frozen nanostructures of the obtained nanoparticles, onion-like in acetone/H2O and large compound micelles in tetrahydrofuran/H2O. By changing the concentration of the block copolymers and the Vsolvent/VH2O ratio to modify the freezing stage at which block copolymer micelles are frozen, we can further control the size of the nanoparticles. Moreover, small molecules (phosphotungstic acid, pyrene, 1-pyrenebutyric acid) can be trapped into the block copolymer nanoparticles via the freezing process. Their distribution in the nanoparticles relies not only on the solvent property, but also on their interactions with block copolymers. The hybrid nanoparticles with ordered distribution of small molecules can be further changed to partially-void nanoparticles. Our study demonstrated that manipulating the freezing of block copolymers in the solvent exchange process is a simple and controllable fabrication method to generate BCP nanoparticles with different architectures.

Biomechanical Strengthening of the Human Cornea Induced by Nanoplatform-Based Transepithelial Riboflavin/UV-A Corneal Cross-Linking.

PubMed

Labate, Cristina; Lombardo, Marco; Lombardo, Giuseppe; De Santo, Maria Penelope

2017-01-01

The purpose of this study was to investigate the biomechanical stiffening effect induced by nanoplatform-based transepithelial riboflavin/UV-A cross-linking protocol using atomic force microscopy (AFM). Twelve eye bank donor human sclerocorneal tissues were investigated using a commercial atomic force microscope operated in force spectroscopy mode. Four specimens underwent transepithelial corneal cross-linking using a hypotonic solution of 0.1% riboflavin with biodegradable polymeric nanoparticles of 2-hydroxypropyl-β-cyclodextrin plus enhancers (trometamol and ethylenediaminetetraacetic acid) and UV-A irradiation with a 10 mW/cm2 device for 9 minutes. After treatment, the corneal epithelium was removed using the Amoils brush, and the Young's modulus of the most anterior stroma was quantified as a function of scan rate by AFM. The results were compared with those collected from four specimens that underwent conventional riboflavin/UV-A corneal cross-linking and four untreated specimens. The average Young's modulus of the most anterior stroma after the nanoplatform-based transepithelial and conventional riboflavin/UV-A corneal cross-linking treatments was 2.5 times (P < 0.001) and 1.7 times (P < 0.001) greater than untreated controls respectively. The anterior stromal stiffness was significantly different between the two corneal cross-linking procedures (P < 0.001). The indentation depth decreased after corneal cross-linking treatments, ranging from an average of 2.4 ± 0.3 μm in untreated samples to an average of 1.2 ± 0.1 μm and 1.8 ± 0.1 μm after nanoplatform-based transepithelial and conventional cross-linking, respectively. The present nanotechnology-based transepithelial riboflavin/UV-A corneal cross-linking was effective to improve the biomechanical strength of the most anterior stroma of the human cornea.

Controllable synthesis of rice-shape Alq3 nanoparticles with single crystal structure

NASA Astrophysics Data System (ADS)

Xie, Wanfeng; Fan, Jihui; Song, Hui; Jiang, Feng; Yuan, Huimin; Wei, Zhixian; Ji, Ziwu; Pang, Zhiyong; Han, Shenghao

2016-10-01

We report the controllable growth of rice-shape nanoparticles of Alq3 by an extremely facile self-assembly approach. Possible mechanisms have been proposed to interpret the formation and controlled process of the single crystal nanoparticles. The field-emission performances (turn-on field 7 V μm-1, maximum current density 2.9 mA cm-2) indicate the potential application on miniaturized nano-optoelectronics devices of Alq3-based. This facile method can potentially be used for the controlled synthesis of other functional complexes and organic nanostructures.

Nanoparticle-Hydrogel: A Hybrid Biomaterial System for Localized Drug Delivery

PubMed Central

Gao, Weiwei; Zhang, Yue; Zhang, Qiangzhe; Zhang, Liangfang

2016-01-01

Nanoparticles have offered a unique set of properties for drug delivery including high drug loading capacity, combinatorial delivery, controlled and sustained drug release, prolonged stability and lifetime, and targeted delivery. To further enhance therapeutic index, especially for localized application, nanoparticles have been increasingly combined with hydrogels to form a hybrid biomaterial system for controlled drug delivery. Herein, we review recent progresses in engineering such nanoparticle-hydrogel hybrid system (namely ‘NP-gel’) with a particular focus on its application for localized drug delivery. Specifically, we highlight four research areas where NP-gel has shown great promises, including (1) passively controlled drug release, (2) stimuli-responsive drug delivery, (3) site-specific drug delivery, and (4) detoxification. Overall, integrating therapeutic nanoparticles with hydrogel technologies creates a unique and robust hybrid biomaterial system that enables effective localized drug delivery. PMID:26951462

Scalable fabrication of size-controlled chitosan nanoparticles for oral delivery of insulin.

PubMed

He, Zhiyu; Santos, Jose Luis; Tian, Houkuan; Huang, Huahua; Hu, Yizong; Liu, Lixin; Leong, Kam W; Chen, Yongming; Mao, Hai-Quan

2017-06-01

Controlled delivery of protein would find diverse therapeutic applications. Formulation of protein nanoparticles by polyelectrolyte complexation between the protein and a natural polymer such as chitosan (CS) is a popular approach. However, the current method of batch-mode mixing faces significant challenges in scaling up while maintaining size control, high uniformity, and high encapsulation efficiency. Here we report a new method, termed flash nanocomplexation (FNC), to fabricate insulin nanoparticles by infusing aqueous solutions of CS, tripolyphosphate (TPP), and insulin under rapid mixing condition (Re > 1600) in a multi-inlet vortex mixer. In comparison with the bulk-mixing method, the optimized FNC process produces CS/TPP/insulin nanoparticles with a smaller size (down to 45 nm) and narrower size distribution, higher encapsulation efficiency (up to 90%), and pH-dependent nanoparticle dissolution and insulin release. The CS/TPP/insulin nanoparticles can be lyophilized and reconstituted without loss of activity, and produced at a throughput of 5.1 g h -1 when a flow rate of 50 mL min -1 is used. Evaluated in a Type I diabetes rat model, the smaller nanoparticles (45 nm and 115 nm) control the blood glucose level through oral administration more effectively than the larger particles (240 nm). This efficient, reproducible and continuous FNC technique is amenable to scale-up in order to address the critical barrier of manufacturing for the translation of protein nanoparticles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cyclodextrin-insulin complex encapsulated polymethacrylic acid based nanoparticles for oral insulin delivery.

PubMed

Sajeesh, S; Sharma, Chandra P

2006-11-15

Present investigation was aimed at developing an oral insulin delivery system based on hydroxypropyl beta cyclodextrin-insulin (HPbetaCD-I) complex encapsulated polymethacrylic acid-chitosan-polyether (polyethylene glycol-polypropylene glycol copolymer) (PMCP) nanoparticles. Nanoparticles were prepared by the free radical polymerization of methacrylic acid in presence of chitosan and polyether in a solvent/surfactant free medium. Dynamic light scattering (DLS) experiment was conducted with particles dispersed in phosphate buffer (pH 7.4) and size distribution curve was observed in the range of 500-800 nm. HPbetaCD was used to prepare non-covalent inclusion complex with insulin and complex was analyzed by Fourier transform infrared (FTIR) and fluorescence spectroscopic studies. HPbetaCD complexed insulin was encapsulated into PMCP nanoparticles by diffusion filling method and their in vitro release profile was evaluated at acidic/alkaline pH. PMCP nanoparticles displayed good insulin encapsulation efficiency and release profile was largely dependent on the pH of the medium. Enzyme linked immunosorbent assay (ELISA) study demonstrated that insulin encapsulated inside the particles was biologically active. Trypsin inhibitory effect of PMCP nanoparticles was evaluated using N-alpha-benzoyl-L-arginine ethyl ester (BAEE) and casein as substrates. Mucoadhesive studies of PMCP nanoparticles were conducted using freshly excised rat intestinal mucosa and the particles were found fairly adhesive. From the preliminary studies, cyclodextrin complexed insulin encapsulated mucoadhesive nanoparticles appear to be a good candidate for oral insulin delivery.

Zinc oxide nanoparticles inhibit murine photoreceptor-derived cell proliferation and migration via reducing TGF-β and MMP-9 expression in vitro.

PubMed

Guo, Da Dong; Li, Qing Ning; Li, Chun Min; Bi, Hong Sheng

2015-04-01

To investigate behaviour and expression of transforming growth factor-β (TGF-β) and matrix metalloproteinases (MMP-9) in murine photoreceptor-derived cells (661W) after incubation with zinc oxide (ZnO) nanoparticles. We explored effects of ZnO nanoparticles on 661W cells using a real-time cell electronic sensing system, flow cytometry, multiple function microplate reading, real-time quantitative PCR detection system and enzyme-linked immunosorbent assay respectively. Our results indicate that ZnO nanoparticles induced overload of calcium and reactive oxygen species within cells, causing formation of apoptotic bodies, disruption of cell cycle distribution, and reduction in expression of TGF-β and MMP-9, to suppress cell proliferation and migration. Our findings show that disruption of intracellular calcium homoeostasis and overproduction of reactive oxygen species were closely associated with reduction of TGF-β and MMP-9 in 661W cells under ZnO nanoparticle treatment. Results of our study indicate that ZnO nanoparticles suppressed cell proliferation and migration, and reduced production of TGF-β and MMP-9 at both gene and protein levels. Our findings contribute to the understanding of the molecular mechanisms that reduced TGF-β and MMP-9 levels inhibit cell proliferation and migration under ZnO nanoparticle influence. © 2015 John Wiley & Sons Ltd.

Functionalization and Characterization of Metal Oxide Coatings of Stainless Steel and Silica Nanoparticles

NASA Astrophysics Data System (ADS)

Slaney, Anne Margaret

The development of tolerogens, fabricated devices eliciting tolerance toward incompatible donor ABO antigens in implant patients, is the ultimate goal of this project. This would permit ABO incompatible organ transplants, increase the donor pool for patients, increase efficiency in the use of available organs, reduce waitlist times and reduce mortality rates of patients. Stainless steel stents and silica nanoparticles were chosen as platforms for the stationary and circulating tolerogens. Stainless steel was coated with silica by solgel dip-coating, electrodeposition, and atomic layer deposition (ALD). The coatings were evaluated by CV, EIS, SEM, AFM, VASE, FTIR, XPS, and AES. Of the silica films, those deposited by ALD provided superior insulating, conformal, and thin coatings. These silica ALD films outperformed even titania ALD films upon stressing. Silica ALD films were subsequently functionalized with mixtures of silane derivatives of poly(ethylene glycol) (PEG), to prevent nonspecific protein binding, and monosaccharides (MS) or trisaccharide and tetrasaccharide (TS) antigens. Functionalizations were characterized by FTIR, XPS and UV-Vis following enzyme-linked lectin assays (ELLAs) or enzyme-linked immunosorbent assays (ELISAs). Effective functionalization allowing biological availability and activity even after incubation in blood plasma was confirmed. Microarray microscope slides were similarly developed with all ABO antigen subtypes, characterized by ToF-SIMS and ELISA, and proved useful in detecting antibodies in human blood samples. Silica nanoparticles, including fluorescent and magnetic varieties, in a range of sizes were prepared by sol-gel synthesis. The nanoparticles were evaluated by SEM, DLS, zeta potential measurements, fluorescence imaging, flow cytometry, two-photon excitation fluorescence correlation spectroscopy and TEM. Different dye incorporation methods were used for effective detection of NPs, and additional silica layers improved fluorophore characteristics. Functionalization of the nanoparticles with PEG and MS or TS were determined successful using three different methods as characterized by FTIR, XPS and ELLA or ELISA and UV-Vis or flow cytometry. The most cost-effective method involved functionalizing nanoparticles with amine, which was optimized using an assay. The amine-terminated nanoparticles were used to tether a PEG linker molecule for covalent binding of PnP derivatives of MSs and TSs.

Biocatalytic Self-Assembly on Magnetic Nanoparticles.

PubMed

Conte, Maria P; Sahoo, Jugal Kishore; Abul-Haija, Yousef M; Lau, K H Aaron; Ulijn, Rein V

2018-01-24

Combining (bio)catalysis and molecular self-assembly provides an effective approach for the production and processing of self-assembled materials by exploiting catalysis to direct the assembly kinetics and hence controlling the formation of ordered nanostructures. Applications of (bio)catalytic self-assembly in biologically interfacing systems and in nanofabrication have recently been reported. Inspired by self-assembly in biological cells, efforts to confine catalysts on flat or patterned surfaces to exert spatial control over molecular gelator generation and nanostructure self-assembly have also emerged. Building on our previous work in the area, we demonstrate in this report the use of enzymes immobilized onto magnetic nanoparticles (NPs) to spatially localize the initiation of peptide self-assembly into nanofibers around NPs. The concept is generalized for both an equilibrium biocatalytic system that forms stable hydrogels and a nonequilibrium system that normally has a preset lifetime. Characterization of the hydrogels shows that self-assembly occurs at the site of enzyme immobilization on the NPs to give rise to gels with a "hub-and-spoke" morphology, where the nanofibers are linked through the enzyme-NP conjugates. This NP-controlled arrangement of self-assembled nanofibers enables both remarkable enhancements in the shear strength of hydrogel systems and a dramatic extension of the hydrogel stability in the nonequilibrium system. We are also able to show that the use of magnetic NPs enables the external control of both the formation of the hydrogel and its overall structure by application of an external magnetic field. We anticipate that the enhanced properties and stimuli-responsiveness of our NP-enzyme system will have applications ranging from nanomaterial fabrication to biomaterials and biosensing.

Aged-engineered nanoparticles effect on sludge anaerobic digestion performance and associated microbial communities.

PubMed

Eduok, Samuel; Ferguson, Robert; Jefferson, Bruce; Villa, Raffaella; Coulon, Frédéric

2017-12-31

To investigate the potential effect of aged engineered nanoparticles (a-ENPs) on sludge digestion performance, 150L pilot anaerobic digesters (AD) were fed with a blend of primary and waste activated sludge spiked either with a mixture of silver oxide, titanium dioxide and zinc oxide or a mixture of their equivalent bulk metal salts to achieve a target concentration of 250, 2000, and 2800mgkg -1 dry weight, respectively. Volatile fatty acids (VFA) were 1.2 times higher in the spiked digesters and significantly different (p=0.05) from the control conditions. Specifically, isovaleric acid concentration was 2 times lower in the control digester compared to the spiked digesters, whereas hydrogen sulfide was 2 times lower in the ENPs spiked digester indicating inhibitory effect on sulfate reducing microorganisms. Based on the ether-linked isoprenoids concentration, the total abundance of methanogens was 1.4 times lower in the ENPs spiked digester than in the control and metal salt spiked digesters. Pyrosequencing indicated 80% decrease in abundance and diversity of methanogens in ENPs spiked digester compared to the control digester. Methanosarcina acetivorans and Methanosarcina barkeri were identified as nano-tolerant as their relative abundance increased by a factor of 6 and 11, respectively, compared to the other digesters. The results further provide compelling evidence on the resilience of Fusobacteria, Actinobacteria and the Trojan horse-like effect of ENPs which offered a competitive advantage to some organisms while reducing microbial abundance and diversity. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Structural and optical properties of novel surfactant-coated Yb@TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Calandra, P.; Lombardo, D.; Pistone, A.; Turco Liveri, V.; Trusso, S.

2011-11-01

In this paper a novel hybrid approach to synthesise composite nanoparticles is presented. It is based on the laser ablation of a bulk target (Yb) immersed in a reversed micellar solution which contains nanoparticles of a different host material (TiO2 nanoparticles) previously synthesised by chemical method. This approach thus exploits the advantages of the chemical synthesis through reversed micellar solution (size control, nanoparticle stabilisation), and of the laser ablation ("clean" synthesis, no side reactions). Central role is played by the microscopic processes controlling the deposition of the ablated Yb atoms onto the surface of TiO2 nanoparticles which actually behave as nucleation seeds. The structural features of the resulting Yb@TiO2 composite nanoparticles have been studied by Transmission Electron Microscopy, whereas their peculiar optical properties have been explored by UV-Vis spectroscopy and steady-state fluorescence. Results consistently show the formation of Yb and TiO2 glued nanodomains to form nearly spherical and non-interacting nanoparticles with enhanced photophysical properties.

Organic nanoparticles for photovoltaic and sensing applications

NASA Astrophysics Data System (ADS)

Venkatraman, B. Harihara

2011-12-01

Can organic semiconducting nanoparticles be used as building blocks for fabricating electronic devices? The first half of this dissertation focuses on addressing this question and the associated research challenges for attaining morphological control pertaining to organic photovoltaic devices by nanoparticle assembly. Conjugated polymer nanoparticles were synthesized using miniemulsion technique and their optical, charge transfer and charge transport properties were studied. Some degree of control in polymer chain packing within the nanoparticle was also demonstrated. The optical, charge transfer and charge transport properties of these nanoparticles were found to be similar to that of parent conjugated polymer irrespective of the surface charge. From the initial photovoltaic measurements, it is shown that these nanoparticles are potential candidates for fabricating future photovoltaic devices. The second half of this dissertation is focused on developing a novel and viable strategy for sensing aqueous based nitroaromatic compounds. Nitroaromatic compounds are commonly used as explosives and possess serious health hazards. Thiophene-based conjugated polymer nanoparticles were synthesized and were shown to effectively detect aqueous based nitroaromatic explosives.

Gold nanoparticles prepared by electro-exploding wire technique in aqueous solutions

NASA Astrophysics Data System (ADS)

Kumar, Lalit; Kapoor, Akanksha; Meghwal, Mayank; Annapoorni, S.

2016-05-01

This article presents an effective approach for the synthesis of Au nanoparticles via an environmentally benevolent electro-exploding wire (EEW) technique. In this process, Au nanoparticles evolve through the plasma generated from the parent Au metal. Compared to other typical chemical methods, electro-exploding wire technique is a simple and economical technique which normally operates in water or organic liquids under ambient conditions. Efficient size control was achieved using different aqueous medium like (1mM) NaCl, deionized water and aqueous solution of sodium hydroxide (NaOH, pH 9.5) using identical electro-exploding conditions. The gold nanoparticles exhibited the UV-vis absorption spectrum with a maximum absorption band at 530 nm, similar to that of gold nanoparticles chemically prepared in a solution. The mechanism of size variation of Au nanoparticles is also proposed. The results obtained help to develop methodologies for the control of EEW based nanoparticle growth and the functionalization of nanoparticle surfaces by specific interactions.

Localized, plasmon-mediated heating from embedded nanoparticles in nanocomposites

NASA Astrophysics Data System (ADS)

Maity, Somsubhra; Downen, Lori; Bochinski, Jason; Clarke, Laura

2010-03-01

Metallic nanoparticles exhibit a surface plasmon resonance which, when excited with visible light, results in a dramatic increase in the nanoparticle temperature. Previously such localized heating has been primarily employed in biomedical research and other experiments involving aqueous environments. In this work, we investigated use of the nanoparticles in solid phase to re-shape, bond, melt, and otherwise process nanofibrous mats of ˜200 nm diameter nanofibers doped with ˜80 nm spherical gold nanoparticles. Under low light intensities (100 mW/cm^2 @ 532 nm) and dilute nanoparticle loading (˜0.15% volume fraction), irradiation of a few minutes melted nanofibrous mats of poly (ethylene oxide) (Tm = 65 degree C). Control samples without gold nanoparticles displayed no melting. Because the heat is generated from within the material and only at the nanoparticle locations, this technique enables true nanoprocessing -- the non-contact, controlled application of heat at specific nano-sized locations within a material to effect desired local changes. Funded by CMMI-0829379.

Spontaneous formation of nanoparticle stripe patterns through dewetting

NASA Astrophysics Data System (ADS)

Huang, Jiaxing; Kim, Franklin; Tao, Andrea R.; Connor, Stephen; Yang, Peidong

2005-12-01

Significant advancement has been made in nanoparticle research, with synthetic techniques extending over a wide range of materials with good control over particle size and shape. A grand challenge is assembling and positioning the nanoparticles in desired locations to construct complex, higher-order functional structures. Controlled positioning of nanoparticles has been achieved in pre-defined templates fabricated by top-down approaches. A self-assembly method, however, is highly desirable because of its simplicity and compatibility with heterogeneous integration processes. Here we report on the spontaneous formation of ordered gold and silver nanoparticle stripe patterns on dewetting a dilute film of polymer-coated nanoparticles floating on a water surface. Well-aligned stripe patterns with tunable orientation, thickness and periodicity at the micrometre scale were obtained by transferring nanoparticles from a floating film onto a substrate in a dip-coating fashion. This facile technique opens up a new avenue for lithography-free patterning of nanoparticle arrays for various applications including, for example, multiplexed surface-enhanced Raman substrates and templated fabrication of higher-order nanostructures.

Tetracycline-Containing MCM-41 Mesoporous Silica Nanoparticles for the Treatment of Escherichia coli.

PubMed

Koneru, Bhuvaneswari; Shi, Yi; Wang, Yu-Chieh; Chavala, Sai H; Miller, Michael L; Holbert, Brittany; Conson, Maricar; Ni, Aiguo; Di Pasqua, Anthony J

2015-10-30

Tetracycline (TC) is a well-known broad spectrum antibiotic, which is effective against many Gram positive and Gram negative bacteria. Controlled release nanoparticle formulations of TC have been reported, and could be beneficial for application in the treatment of periodontitis and dental bone infections. Furthermore, TC-controlled transcriptional regulation systems (Tet-on and Tet-off) are useful for controlling transgene expression in vitro and in vivo for biomedical research purposes; controlled TC release systems could be useful here, as well. Mesoporous silica nanomaterials (MSNs) are widely studied for drug delivery applications; Mobile crystalline material 41 (MCM-41), a type of MSN, has a mesoporous structure with pores forming channels in a hexagonal fashion. We prepared 41 ± 4 and 406 ± 55 nm MCM-41 mesoporous silica nanoparticles and loaded TC for controlled dug release; TC content in the TC-MCM-41 nanoparticles was 18.7% and 17.7% w/w, respectively. Release of TC from TC-MCM-41 nanoparticles was then measured in phosphate-buffered saline (PBS), pH 7.2, at 37 °C over a period of 5 h. Most antibiotic was released from both over this observation period; however, the majority of TC was released over the first hour. Efficacy of the TC-MCM-41 nanoparticles was then shown to be superior to free TC against Escherichia coli (E. coli) in culture over a 24 h period, while blank nanoparticles had no effect.

Effects of plasmonic field due to gold nanoparticles and magnetic field on photocurrents of zinc porphyrin-viologen linked compound-gold nanoparticle composite films

NASA Astrophysics Data System (ADS)

Yonemura, Hiroaki; Niimi, Tomoki; Yamada, Sunao

2016-03-01

Composite films of zinc-porphyrin-viologen (ZnP-V2+) linked compound containing six methylene group [ZnP(6)V]-gold nanoparticles (AuNP) were fabricated by combining electrostatic layer-by-layer adsorption and the Langmuir-Blodgett method. The anodic photocurrents of the ZnP(6)V-AuNP composite films are higher than those of the ZnP(6)V films. The large photocurrents in ZnP(6)V-AuNP composite films are most likely attributable to the combination of localized surface plasmon resonance due to AuNP and photoinduced intramolecular electron transfer from excited state of ZnP to V2+. The photocurrents of the ZnP(6)V-AuNP composite films increase in the presence of magnetic field. The photocurrents increase with low magnetic fields (B ≤ 150 mT) and are almost constant under high magnetic fields (B ≥ 150 mT). Magnetic field effects (MFEs) were clearly observed for both ZnP(6)V-AuNP composite films and ZnP(6)V films. The MFEs can be explained by a radical pair mechanism.

Flexible all-solid-state supercapacitors based on graphene/carbon black nanoparticle film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes

NASA Astrophysics Data System (ADS)

Fei, Haojie; Yang, Chongyang; Bao, Hua; Wang, Gengchao

2014-11-01

Flexible all-solid-state supercapacitors (SCs) are fabricated using graphene/carbon black nanoparticle (GCB) film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes (gPVAP-H2SO4). The GCB composite films, with carbon black (CB) nanoparticles uniformly distributed in the graphene nanosheets, greatly improve the active surface areas and ion transportation of pristine graphene film. The porous structure of as-prepared gPVAP-H2SO4 membrane improves the equilibrium swelling ratio in electrolyte and provides interconnected ion transport channels. The chemical crosslinking solves the fluidity problem of PVA-H2SO4 gel electrolyte at high temperature. As-fabricated GCB//gPVAP(20)-H2SO4//GCB flexible SC displays an increased specific capacitance (144.5 F g-1 at 0.5 A g-1) and a higher specific capacitance retention (67.9% from 0.2 to 4 A g-1). More importantly, the flexible SC possesses good electrochemical performance at high temperature (capacitance retention of 78.3% after 1000 cycles at 70 °C).

Durable antibacterial and cross-linking cotton with colloidal silver nanoparticles and butane tetracarboxylic acid without yellowing.

PubMed

Montazer, Majid; Alimohammadi, Farbod; Shamei, Ali; Rahimi, Mohammad Karim

2012-01-01

Colloidal nano silver was applied on the surface of cotton fabric and stabilized using 1,2,3,4-butanetetracarboxylic acid (BTCA). The two properties of antimicrobial activity and resistance against creasing were imparted to the samples of fabric as a result of the treatment with silver nano colloid and BTCA. The antimicrobial property of samples was evaluated using two pathogenic bacteria including Escherichia coli and Staphylococcus aureus as outstanding barometers in this field. The durability of applied nanoparticles, color variation, wettability and wrinkle recovery angle of the treated samples were investigated employing related credible standards. The presence of nano silver particles on the surface of treated cotton fabric was proved using EDS spectrum as well as the SEM images. Furthermore, the creation of cross-links was confirmed by the means of both ATR-FTIR and Raman spectra. In conclusion, it was observed that BTCA plays a prominent role in stabilizing silver nanoparticle. Besides, Wettability and winkle recovery angle of finished samples decreased and increased, respectively. In addition, it is noteworthy that no obvious color variation was observed. Copyright © 2011 Elsevier B.V. All rights reserved.

Improved self-healing of polyethylene/carbon black nanocomposites by their shape memory effect.

PubMed

Wang, Xiaoyan; Zhao, Jun; Chen, Min; Ma, Lan; Zhao, Xiaodong; Dang, Zhi-Min; Wang, Zhenwen

2013-02-07

In this work, the improved self-healing of cross-linked polyethylene (PE) (cPE)/carbon black (CB) nanocomposites by their shape memory effect (SME) is investigated. CB nanoparticles are found to be homogeneously dispersed in the PE matrix and significantly increase the strength of the materials. Compared with the breaking of linear PE (lPE) at the melting temperature (T(m)), the cPE and cPE/CB nanocomposites still have high strength above T(m) due to the formation of networks. The cPE and cPE/CB nanocomposites show both high strain fixity ratio (R(f)) and high strain recovery ratio (R(r)). Crystallization-induced elongation is observed for all the prepared shape memory polymer (SMP) materials and the effect becomes less remarkable with increasing volume fraction of CB nanoparticles (v(CB)). The scratch self-healing tests show that the cross-linking of PE matrix, the addition of CB nanoparticles, and the previous stretching in the direction perpendicular to the scratch favor the closure of the scratch and its complete healing. This SME-aided self-healing could have potential applications in diverse fields such as coating and structure materials.

Dual-color plasmonic enzyme-linked immunosorbent assay based on enzyme-mediated etching of Au nanoparticles

NASA Astrophysics Data System (ADS)

Guo, Longhua; Xu, Shaohua; Ma, Xiaoming; Qiu, Bin; Lin, Zhenyu; Chen, Guonan

2016-09-01

Colorimetric enzyme-linked immunosorbent assay utilizing 3‧-3-5‧-5-tetramethylbenzidine(TMB) as the chromogenic substrate has been widely used in the hospital for the detection of all kinds of disease biomarkers. Herein, we demonstrate a strategy to change this single-color display into dual-color responses to improve the accuracy of visual inspection. Our investigation firstly reveals that oxidation state of 3‧-3-5‧-5-tetramethylbenzidine (TMB2+) can quantitatively etch gold nanoparticles. Therefore, the incorporation of gold nanoparticles into a commercial TMB-based ELISA kit could generate dual-color responses: the solution color varied gradually from wine red (absorption peak located at ~530 nm) to colorless, and then from colorless to yellow (absorption peak located at ~450 nm) with the increase amount of targets. These dual-color responses effectively improved the sensitivity as well as the accuracy of visual inspection. For example, the proposed dual-color plasmonic ELISA is demonstrated for the detection of prostate-specific antigen (PSA) in human serum with a visual limit of detection (LOD) as low as 0.0093 ng/mL.

Optical assays based on colloidal inorganic nanoparticles.

PubMed

Ghasemi, Amir; Rabiee, Navid; Ahmadi, Sepideh; Hashemzadeh, Shabnam; Lolasi, Farshad; Bozorgomid, Mahnaz; Kalbasi, Alireza; Nasseri, Behzad; Shiralizadeh Dezfuli, Amin; Aref, Amir Reza; Karimi, Mahdi; Hamblin, Michael R

2018-06-20

Colloidal inorganic nanoparticles have wide applications in the detection of analytes and in biological assays. A large number of these assays rely on the ability of gold nanoparticles (AuNPs, in the 20 nm diameter size range) to undergo a color change from red to blue upon aggregation. AuNP assays can be based on cross-linking, non-cross linking or unmodified charge-based aggregation. Nucleic acid-based probes, monoclonal antibodies, and molecular-affinity agents can be attached by covalent or non-covalent means. Surface plasmon resonance and SERS techniques can be utilized. Silver NPs also have attractive optical properties (higher extinction coefficient). Combinations of AuNPs and AgNPs in nanocomposites can have additional advantages. Magnetic NPs and ZnO, TiO2 and ZnS as well as insulator NPs including SiO2 can be employed in colorimetric assays, and some can act as peroxidase mimics in catalytic applications. This review covers the synthesis and stabilization of inorganic NPs and their diverse applications in colorimetric and optical assays for analytes related to environmental contamination (metal ions and pesticides), and for early diagnosis and monitoring of diseases, using medically important biomarkers.

Biphasic magnetic nanoparticles-nanovesicle hybrids for chemotherapy and self-controlled hyperthermia.

PubMed

Gogoi, Manashjit; Sarma, Haladhar D; Bahadur, Dhirendra; Banerjee, Rinti

2014-05-01

The aim was to develop magnetic nanovesicles for chemotherapy and self-controlled hyperthermia that prevent overheating of tissues. Magnetic nanovesicles containing paclitaxel and a dextran-coated biphasic suspension of La0.75Sr0.25MnO3 and Fe3O4 nanoparticles (magnetic nanoparticles) were developed. Encapsulation efficiencies of magnetic nanoparticles and paclitaxel were 67 ± 5 and 83 ± 3%, respectively. Sequential release performed at 37°C for 1 h followed by 44°C for another 1 h (as expected for intratumoral injection), showed a cumulative release of 6.6% (109.6 µg), which was above the IC50 of the drug. In an alternating current magnetic field, the temperature remained controlled at 44°C and a synergistic cytotoxicity of paclitaxel and hyperthermia was observed in MCF-7 cells. Magnetic nanovesicles containing biphasic suspensions La0.75Sr0.25MnO3 and Fe3O4 nanoparticles encapsulating paclitaxel have potential for combined self-controlled hyperthermia and chemotherapy.

Thermal Decomposition Synthesis of Iron Oxide Nanoparticles with Diminished Magnetic Dead Layer by Controlled Addition of Oxygen.

PubMed

Unni, Mythreyi; Uhl, Amanda M; Savliwala, Shehaab; Savitzky, Benjamin H; Dhavalikar, Rohan; Garraud, Nicolas; Arnold, David P; Kourkoutis, Lena F; Andrew, Jennifer S; Rinaldi, Carlos

2017-02-28

Decades of research focused on size and shape control of iron oxide nanoparticles have led to methods of synthesis that afford excellent control over physical size and shape but comparatively poor control over magnetic properties. Popular synthesis methods based on thermal decomposition of organometallic precursors in the absence of oxygen have yielded particles with mixed iron oxide phases, crystal defects, and poorer than expected magnetic properties, including the existence of a thick "magnetically dead layer" experimentally evidenced by a magnetic diameter significantly smaller than the physical diameter. Here, we show how single-crystalline iron oxide nanoparticles with few defects and similar physical and magetic diameter distributions can be obtained by introducing molecular oxygen as one of the reactive species in the thermal decomposition synthesis. This is achieved without the need for any postsynthesis oxidation or thermal annealing. These results address a significant challenge in the synthesis of nanoparticles with predictable magnetic properties and could lead to advances in applications of magnetic nanoparticles.

Aerosol emission monitoring in the production of silicon carbide nanoparticles by induction plasma synthesis

NASA Astrophysics Data System (ADS)

Thompson, Drew; Leparoux, Marc; Jaeggi, Christian; Buha, Jelena; Pui, David Y. H.; Wang, Jing

2013-12-01

In this study, the synthesis of silicon carbide (SiC) nanoparticles in a prototype inductively coupled thermal plasma reactor and other supporting processes, such as the handling of precursor material, the collection of nanoparticles, and the cleaning of equipment, were monitored for particle emissions and potential worker exposure. The purpose of this study was to evaluate the effectiveness of engineering controls and best practice guidelines developed for the production and handling of nanoparticles, identify processes which result in a nanoparticle release, characterize these releases, and suggest possible administrative or engineering controls which may eliminate or control the exposure source. No particle release was detected during the synthesis and collection of SiC nanoparticles and the cleaning of the reactor. This was attributed to most of these processes occurring in closed systems operated at slight underpressure. Other tasks occurring in more open spaces, such as the disconnection of a filter assembly from the reactor system and the use of compressed air for the cleaning of filters where synthesized SiC nanoparticles were collected, resulted in releases of submicrometer particles with a mode size of 170-180 nm. Observation of filter samples under scanning electron microscope confirmed that the particles were agglomerates of SiC nanoparticles.

Acacia nilotica (Babool) leaf extract mediated size-controlled rapid synthesis of gold nanoparticles and study of its catalytic activity

NASA Astrophysics Data System (ADS)

Majumdar, Rakhi; Bag, Braja Gopal; Maity, Nabasmita

2013-09-01

The leaf extract of Acacia nilotica (Babool) is rich in different types of plant secondary metabolites such as flavanoids, tannins, triterpenoids, saponines, etc. We have demonstrated the use of the leaf extract for the synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete in several minutes, and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the leaf extract. The gold nanoparticles were characterized by HRTEM, surface plasmon resonance spectroscopy, and X-ray diffraction studies. The synthesized gold nanoparticles have been used as an efficient catalyst for the reduction of 4-nitrophenol to 4-aminophenol in water at room temperature.

Facile synthesis of biocompatible gold nanoparticles with organosilicone-coated surface properties

NASA Astrophysics Data System (ADS)

Xia, Lijin; Yi, Sijia; Lenaghan, Scott C.; Zhang, Mingjun

2012-07-01

In this study, a simple method for one-step synthesis of gold nanoparticles has been developed using an organosilicone surfactant, Silwet L-77, as both a reducing and capping agent. Synthesis of gold nanoparticles using this method is rapid and can be conducted conveniently at ambient temperature. Further refinement of the method, through the addition of sodium hydroxide and/or silver nitrate, allowed fine control over the size of spherical nanoparticles produced. Coated on the surface with organosilicone, the as-prepared gold nanoparticles were biocompatible and stable over the pH range from 5 to 12, and have been proven effective at transportation into MC3T3 osteoblast cells. The proposed method is simple, fast, and can produce size-controlled gold nanoparticles with unique surface properties for biomedical applications.

Plasmonic properties and enhanced fluorescence of gold and dye-doped silica nanoparticle aggregates

NASA Astrophysics Data System (ADS)

Green, Nathaniel Scott

The development of metal-enhanced fluorescence has prompted a great interest in augmenting the photophysical properties of fluorescent molecules with noble metal nanostructures. Our research efforts, outlined in this dissertation, focus on augmenting properties of fluorophores by conjugation with gold nanostructures. The project goals are split into two separate efforts; the enhancement in brightness of fluorophores and long distance non-radiative energy transfer between fluorophores. We believe that interacting dye-doped silica nanoparticles with gold nanoparticles can facilitate both of these phenomena. Our primary research interest is focused on optimizing brightness, as this goal should open a path to studying the second goal of non-radiative energy transfer. The two major challenges to this are constructing suitable nanomaterials and functionalizing them to promote plasmonically active complexes. The synthesis of dye-doped layered silica nanoparticles allows for control over the discrete location of the dye and a substrate that can be surface functionalized. Controlling the exact location of the dye is important to create a silica spacer, which promotes productive interactions with metal nanostructures. Furthermore, the synthesis of silica nanoparticles allows for various fluorophores to be studied in similar environments (removing solvent and other chemo-sensitive issues). Functionalizing the surface of silica nanoparticles allows control over the degree of silica and gold nanoparticle aggregation in solution. Heteroaggregation in solution is useful for producing well-aggregated clusters of many gold around a single silica nanoparticle. The dye-doped surface functionalized silica nanoparticles can than be mixed efficiently with gold nanomaterials. Aggregating multiple gold nanospheres around a single dye-doped silica nanoparticle can dramatically increase the fluorescent brightness of the sample via metal-enhanced fluorescence due to increase plasmonic scattering. Our aim is to promote heteroaggregation with functionalized silica nanoparticles while minimizing homoaggregation of silica-silica or gold-gold species. Reproducible production of multiple gold nanospheres about a dye-doped silica nanoparticle should lead to dramatic fluorescence brightness enhancements in solution. Gold nanorods can potentially be used to establish radiationless energy transfer between hetero dye-doped silica nanoparticles via gold nanorod plasmon mediated FRET by aggregating two different dye-doped silica nanoparticles preferentially at opposite ends of the nanorod. End-cap binding is accomplished by tuning the strength of gold binding ligands that functionalize the surface of the silica nanoparticles. The gold nanorod can then theoretically serve as a waveguide by employing the longitudinal plasmon as a non-radiative energy transfer agent between the two different fluorophores, giving rise to a new ultrafast signaling paradigm. Heteroaggregation of dye-doped silica nanoparticles and gold nanorods can be potentially employed to as nano waveguides. Construction and aggregation of functionalized silica and gold nano-materials provides an opportunity to advance the field of fluorescence. The synthesis of gold nano-particles allows control over their size and shape, which give rise to useful optical and electronic properties. Silica nanoparticles provide a framework allowing control over a requisite distance for increasing beneficial and deceasing non-radiative dye-metal interactions as well fluorophore protection. Our aim is to take advantage of fine-tuned synthetic control of functionalized nanomaterials to realize the great potential of solution based metal-enhanced fluorescence for future applications.

Seed-mediated synthesis of cross-linked Pt-NiO nanochains for methanol oxidation

NASA Astrophysics Data System (ADS)

Gu, Zhulan; Bin, Duan; Feng, Yue; Zhang, Ke; Wang, Jin; Yan, Bo; Li, Shumin; Xiong, Zhiping; Wang, Caiqin; Shiraishi, Yukihide; Du, Yukou

2017-07-01

A simple method was reported for employing NiO nanoparticles act as seeds and then different amounts of Pt2+ were reduced on the NiO nanoparticles, forming a cross-linked Pt-NiO nanocatalysts. These as-prepared catalysts were characterized using different physical-chemical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the morphology of the cross-linked Pt-NiO nanochain was successfully produced regardless of the molar ratio of Pt2+ to NiO precursors. The electrochemical characteristics of Pt-NiO nanochain catalysts were evaluated for the oxidation of methanol as a model reaction, which verify that the Pt-NiO catalysts show enhanced activity and high stability in comparison with the commercial Pt/C catalyst. The optimized ratio of Pt to NiO is 1:1, then tuned by simple adjusting the feed ratio of the precursors as well. The synthesized nanocatalysts will be found the great potential applications as electrocatalysts for fuel cells owe to their enhanced catalytic performance and long-term stability.

Lipid nanoparticle interactions and assemblies

NASA Astrophysics Data System (ADS)

Preiss, Matthew Ryan

Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron oxide nanoparticles encapsulated in the lipid bilayer, the local temperature and membrane fluidity could be observed. DLNAs were encapsulated with different sized nanoparticles and concentrations in order to observe the effect of the bilayer nanoparticles on the lipid bilayer's phase behavior and leakage. Two different sized nanoparticles were used, a 2 nm gold nanoparticle (GNP) much smaller than the thickness of the bilayer and a 4 nm GNP near the thickness of the lipid bilayer. The 2 nm GNPs were shown to affect the lipid bilayer differently than the 4 nm GNP. Specifically, the two nanoparticles altered the phase behavior and leakage differently in a temperature dependent fashion, demonstrating that embedded nanoparticle size can be used induce or inhibit bilayer leakage. A dual solvent exchange method was used to control the lipid surface composition of an iron oxide nanoparticle with a cationic lipid and a polyethylene glycol (PEG) lipid to produce lipid coated magnetic nanoparticles (LMNPs). PEG is well known for its ability to enhance the pharmacokinetics of nanostructures by preventing uptake by the immune system. By controlling the lipid surface composition, the surface charge and PEG conformation can be controlled which allowed the LMNPs to be used as an MRI contrast agent and a delivery system for siRNA that could be triggered with temperature.

Template assisted synthesis and optical properties of gold nanoparticles.

NASA Astrophysics Data System (ADS)

Fodor, Petru; Lasalvia, Vincenzo

2009-03-01

A hybrid nanofabrication method (interference lithography + self assembly) was explored for the fabrication of arrays of gold nanoparticles. To ensure the uniformity of the nanoparticles, a template assisted synthesis was used in which the gold is electrodeposited in the pores of anodized aluminum membranes. The spacing between the pores and their ordering is controlled in the first fabrication step of the template in which laser lithography and metal deposition are used to produce aluminum films with controlled strain profiles. The diameter of the pores produced after anodizing the aluminum film in acidic solution determines the diameter of the gold particles, while their aspect ratio is controlled through the deposition time. Optical absorbance spectroscopy is used to evaluate the ability to tune the nanoparticles plasmon resonance spectra through control over their size and aspect ratio.

Synthesis and characterization of silver nanoparticle composite with poly(p-Br-phenylsilane).

PubMed

Kim, Myoung-Hee; Lee, Jun; Mo, Soo-Yong; Woo, Hee-Gweon; Yang, Kap Seung; Kim, Bo-Hye; Lee, Byeong-Gweon; Sohn, Honglae

2012-05-01

The one-pot synthesis and characterization of silver nanoparticle-poly(p-Br-phenylsilane) composites have been carried out. The conversion of silver(+1) salt to stable silver(0) nanoparticles is promoted by poly(p-Br-phenylsilane), Br-PPS possessing both possible reactive Si-H bonds in the polymer backbone and C-Br bonds in the substituents. The composites were characterized using XRD, TEM, FE-SEM, and solid-state UV-vis analytical techniques. TEM and FE-SEM data show the formation of the composites where large number of silver nanoparticles (less than 30 nm of size) are well dispersed throughout the Br-PPS matrix. XRD patterns are consistent with that for fcc-typed silver. The elemental analysis for Br atom and the polymer solubility confirm that the cleavage of C-Br bond and the Si-Br dative bonding were not occurred appreciably at ambient temperature. Nonetheless, TGA data suggest that some sort of cross-linking was occurred at high temperature. The size and processability of such nanoparticles depend on the ratio of metal to Br-PPS. In the absence of Br-PPS, most of the silver particles undergo macroscopic aggregation, which indicates that the polysilane is necessary for stabilizing the silver nanoparticles.

Size effect on the magnetic properties of antiferromagnetic La0.2Ca0.8MnO3 nanoparticles

NASA Astrophysics Data System (ADS)

Markovich, V.; Fita, I.; Wisniewski, A.; Mogilyansky, D.; Puzniak, R.; Titelman, L.; Martin, C.; Gorodetsky, G.

2010-03-01

Magnetic properties of electron-doped La0.2Ca0.8MnO3 manganite nanoparticles with average particle size ranging from 15 to 37 nm, prepared by the glycine-nitrate method, have been investigated in temperature range 5-300 K and in magnetic fields up to 90 kOe. A monotonous enhancement of weak ferromagnetism linked to the reduction in the particle size was observed for all nanoparticles. Magnetic hysteresis loops also indicate size-dependent exchange bias effect displayed by horizontal and vertical shifts in field-cooled processes. The magnetization data reveal two ferromagnetic components: first one appears at T˜200K and may be attributed to surface magnetization and second one appears as a result of spin canting of antiferromagnetic core or is developed at some interfaces inside nanoparticles. Time evolution of magnetization recorded in magnetic fields after the field cooling to low temperatures exhibits a very noisy behavior that may be caused by formation of collective state of nanoparticles with no clear tendency to reach equilibrium state. Magnetic properties of the nanoparticle samples are compared with those of the bulk La0.2Ca0.8MnO3 .

Robust antireflection coatings By UV cross-linking of silica nanoparticles and diazo-resin polycation

NASA Astrophysics Data System (ADS)

Ridley, Jason I.; Heflin, James R.; Ritter, Alfred L.

2007-09-01

Antireflection coatings have been fabricated by self-assembly using silica nanoparticles. The ionic self-assembled multilayer (ISAM) films are tightly packed and homogeneous. While the geometric properties of a matrix of spherical particles with corresponding void interstices are highly suitable to meet the conditions for minimal reflectivity, it is also a cause for the lack of cohesion within the constituent body, as well as to the substrate surface. This study investigates methods for improving the interconnectivity of the nanoparticle structure. One such method involves UV curing of diazo-resin (DAR)/silica nanoparticle films, thereby converting the ionic interaction into a stronger covalent bond. Factorial analysis and response surface methods are incorporated to determine factors that affect film properties, and to optimize their optical and adhesive capabilities. The second study looks at the adhesive strength of composite multilayer films. Films are fabricated with silica nanoparticles and poly(allylamine hydrochloride) (PAH), and dipped into aqueous solutions of PAH and poly(methacrylic acid, sodium salt) (PMA) to improve cohesion of silica nanoparticles in the matrix, as well as binding strength to the substrate surface. The results of the two studies are discussed.

Highly efficient antibody immobilization with multimeric protein Gs coupled magnetic silica nanoparticles

NASA Astrophysics Data System (ADS)

Lee, J. H.; Choi, H. K.; Chang, J. H.

2011-10-01

This work reports the immobilization of monomeric, dimeric and trimer protein Gs onto silica magnetic nanoparticles for self-oriented antibody immobilization. To achieve this, we initially prepared the silica-coated magnetic nanoparticle having about 170 nm diameters. The surface of the silica coated magnetic nanoparticles was modified with 3- aminopropyl-trimethoxysilane (APTMS) to chemically link to multimeric protein Gs. The conjugation of amino groups on the SiO2-MNPs to cysteine tagged in multimeric protein Gs was performed using a sulfo-SMCC coupling procedure. The binding efficiencies of monomer, dimer and trimer were 77 %, 67 % and 55 % respectively. However, the efficiencies of antibody immobilization were 70 %, 83 % and 95 % for monomeric, dimeric and trimeric protein G, respectively. To prove the enhancement of accessibility by using multimeric protein G, FITC labeled goat-anti-mouse IgG was treated to mouse IgG immobilized magnetic silica nanoparticles through multimeric protein G. FITC labeled goat anti-mouse IgGs were more easily bound to mouse IgG immobilized by trimeric protein G than others. Finally protein G bound silica magnetic nanoparticles were utilized to develop highly sensitive immunoassay to detect hepatitis B antigen.

Evaluation of Flexural Strength of Polymethyl Methacrylate modified with Silver Colloidal Nanoparticles subjected to Two Different Curing Cycles: An in vitro Study.

PubMed

Munikamaiah, Ranganath L; Jain, Saket K; Pal, Kapil S; Gaikwad, Ajay

2018-03-01

Silver colloidal nanoparticles have been incorporated into acrylic resins to induce antimicrobial properties. However, as additives, they can influence the mechanical properties of the final product. Mechanical properties are also dependent on different curing cycles. The aim of this study was to evaluate flexural strength of a denture base resin incorporated with different concentrations of silver colloidal nanoparticles subjected to two different curing cycles. Lucitone 199 denture base resin was used into which silver colloidal nanoparticles were incorporated at 0.5 and 5% by polymer mass. Specimens devoid of nanoparticles were used as controls. A total of 60 specimens were fabricated and divided into two groups. Each group was divided into three subgroups consisting of 10 specimens each. The specimens were fabricated according to American Dental Association (ADA) specification No. 12 and tested for flexural strength using universal testing machine. Silver colloidal nanoparticle incorporation at 0.5% concentration increased the mean flexural strength in both curing cycles by 7.5 and 4.4%, respectively, when compared with the control group. The study suggested that the mean flexural strength value of 0.5% silver colloidal nanoparticles in denture base resin was above the value of the control group both in short and long curing cycles, which makes it clinically suitable as a denture base material. However, at 5% concentration, the statistically significant amount of decrease in flexural strength compared with the value of control group both in short and long curing cycles gives it a questionable prognosis. The specimens incorporated with the antimicrobial agent 0.5% silver colloidal nanoparticles and processed by long curing cycles showed significant increase in its flexural strength compared with the control group, which makes it clinically suitable as a denture base material.

The controlled release of tilmicosin from silica nanoparticles.

PubMed

Song, Meirong; Li, Yanyan; Fai, Cailing; Cui, Shumin; Cui, Baoan

2011-06-01

The aim of this study was to use silica nanoparticles as the carrier for controlled release of tilmicosin. Tilmicosin was selected as a drug model molecule because it has a lengthy elimination half-life and a high concentration in milk after subcutaneous administration. Three samples of tilmicosin-loaded silica nanoparticles were prepared with different drug-loading weight. The drug-loading weight in three samples, as measured by thermal gravimetric analysis, was 29%, 42%, and 64%, respectively. With increased drug-loading weight, the average diameter of the drug-loaded silica nanoparticles was increased from 13.4 to 25.7 nm, and the zeta potential changed from-30.62 to-6.78 mV, indicating that the stability of the drug-loaded particles in the aqueous solution decreases as drug-loading weight increases. In vitro release studies in phosphate-buffered saline showed the sample with 29% drug loading had a slow and sustained drug release, reaching 44% after 72 h. The release rate rose with increased drug-loading weight; therefore, the release of tilmicosin from silica nanoparticles was well-controlled by adjusting the drug loading. Finally, kinetics analysis suggested that drug released from silica nanoparticles was mainly a diffusion-controlled process.

Natural Non-Mulberry Silk Nanoparticles for Potential-Controlled Drug Release

PubMed Central

Wang, Juan; Yin, Zhuping; Xue, Xiang; Kundu, Subhas C.; Mo, Xiumei; Lu, Shenzhou

2016-01-01

Natural silk protein nanoparticles are a promising biomaterial for drug delivery due to their pleiotropic properties, including biocompatibility, high bioavailability, and biodegradability. Chinese oak tasar Antheraea pernyi silk fibroin (ApF) nanoparticles are easily obtained using cations as reagents under mild conditions. The mild conditions are potentially advantageous for the encapsulation of sensitive drugs and therapeutic molecules. In the present study, silk fibroin protein nanoparticles are loaded with differently-charged small-molecule drugs, such as doxorubicin hydrochloride, ibuprofen, and ibuprofen-Na, by simple absorption based on electrostatic interactions. The structure, morphology and biocompatibility of the silk nanoparticles in vitro are investigated. In vitro release of the drugs from the nanoparticles depends on charge-charge interactions between the drugs and the nanoparticles. The release behavior of the compounds from the nanoparticles demonstrates that positively-charged molecules are released in a more prolonged or sustained manner. Cell viability studies with L929 demonstrated that the ApF nanoparticles significantly promoted cell growth. The results suggest that Chinese oak tasar Antheraea pernyi silk fibroin nanoparticles can be used as an alternative matrix for drug carrying and controlled release in diverse biomedical applications. PMID:27916946

Controlling the net charge on a nanoparticle optically levitated in vacuum

NASA Astrophysics Data System (ADS)

Frimmer, Martin; Luszcz, Karol; Ferreiro, Sandra; Jain, Vijay; Hebestreit, Erik; Novotny, Lukas

2017-06-01

Optically levitated nanoparticles in vacuum are a promising model system to test physics beyond our current understanding of quantum mechanics. Such experimental tests require extreme control over the dephasing of the levitated particle's motion. If the nanoparticle carries a finite net charge, it experiences a random Coulomb force due to fluctuating electric fields. This dephasing mechanism can be fully excluded by discharging the levitated particle. Here, we present a simple and reliable technique to control the charge on an optically levitated nanoparticle in vacuum. Our method is based on the generation of charges in an electric discharge and does not require additional optics or mechanics close to the optical trap.

Design of Super-Paramagnetic Core-Shell Nanoparticles for Enhanced Performance of Inverted Polymer Solar Cells.

PubMed

Jaramillo, Johny; Boudouris, Bryan W; Barrero, César A; Jaramillo, Franklin

2015-11-18

Controlling the nature and transfer of excited states in organic photovoltaic (OPV) devices is of critical concern due to the fact that exciton transport and separation can dictate the final performance of the system. One effective method to accomplish improved charge separation in organic electronic materials is to control the spin state of the photogenerated charge-carrying species. To this end, nanoparticles with unique iron oxide (Fe3O4) cores and zinc oxide (ZnO) shells were synthesized in a controlled manner. Then, the structural and magnetic properties of these core-shell nanoparticles (Fe3O4@ZnO) were tuned to ensure superior performance when they were incorporated into the active layers of OPV devices. Specifically, small loadings of the core-shell nanoparticles were blended with the previously well-characterized OPV active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Upon addition of the core-shell nanoparticles, the performance of the OPV devices was increased up to 25% relative to P3HT-PCBM active layer devices that contained no nanoparticles; this increase was a direct result of an increase in the short-circuit current densities of the devices. Furthermore, it was demonstrated that the increase in photocurrent was not due to enhanced absorption of the active layer due to the presence of the Fe3O4@ZnO core-shell nanoparticles. In fact, this increase in device performance occurred because of the presence of the superparamagnetic Fe3O4 in the core of the nanoparticles as incorporation of ZnO only nanoparticles did not alter the device performance. Importantly, however, the ZnO shell of the nanoparticles mitigated the negative optical effect of Fe3O4, which have been observed previously. This allowed the core-shell nanoparticles to outperform bare Fe3O4 nanoparticles when the single-layer nanoparticles were incorporated into the active layer of OPV devices. As such, the new materials described here present a tangible pathway toward the development of enhanced design schemes for inorganic nanoparticles such that magnetic and energy control pathways can be tailored for flexible electronic applications.

A dose-controlled system for air-liquid interface cell exposure and application to zinc oxide nanoparticles

PubMed Central

2009-01-01

Background Engineered nanoparticles are becoming increasingly ubiquitous and their toxicological effects on human health, as well as on the ecosystem, have become a concern. Since initial contact with nanoparticles occurs at the epithelium in the lungs (or skin, or eyes), in vitro cell studies with nanoparticles require dose-controlled systems for delivery of nanoparticles to epithelial cells cultured at the air-liquid interface. Results A novel air-liquid interface cell exposure system (ALICE) for nanoparticles in liquids is presented and validated. The ALICE generates a dense cloud of droplets with a vibrating membrane nebulizer and utilizes combined cloud settling and single particle sedimentation for fast (~10 min; entire exposure), repeatable (<12%), low-stress and efficient delivery of nanoparticles, or dissolved substances, to cells cultured at the air-liquid interface. Validation with various types of nanoparticles (Au, ZnO and carbon black nanoparticles) and solutes (such as NaCl) showed that the ALICE provided spatially uniform deposition (<1.6% variability) and had no adverse effect on the viability of a widely used alveolar human epithelial-like cell line (A549). The cell deposited dose can be controlled with a quartz crystal microbalance (QCM) over a dynamic range of at least 0.02-200 μg/cm2. The cell-specific deposition efficiency is currently limited to 0.072 (7.2% for two commercially available 6-er transwell plates), but a deposition efficiency of up to 0.57 (57%) is possible for better cell coverage of the exposure chamber. Dose-response measurements with ZnO nanoparticles (0.3-8.5 μg/cm2) showed significant differences in mRNA expression of pro-inflammatory (IL-8) and oxidative stress (HO-1) markers when comparing submerged and air-liquid interface exposures. Both exposure methods showed no cellular response below 1 μg/cm2 ZnO, which indicates that ZnO nanoparticles are not toxic at occupationally allowed exposure levels. Conclusion The ALICE is a useful tool for dose-controlled nanoparticle (or solute) exposure of cells at the air-liquid interface. Significant differences between cellular response after ZnO nanoparticle exposure under submerged and air-liquid interface conditions suggest that pharmaceutical and toxicological studies with inhaled (nano-)particles should be performed under the more realistic air-liquid interface, rather than submerged cell conditions. PMID:20015351

A Novel Method for Assessing Respiratory Deposition of Welding Fume Nanoparticles

PubMed Central

Cena, L. G.; Keane, M. J.; Chisholm, W. P.; Stone, S.; Harper, M.; Chen, B. T.

2016-01-01

Welders are exposed to high concentrations of nanoparticles. Compared to larger particles, nanoparticles have been associated with more toxic effects at the cellular level, including the generation of more reactive oxygen species activity. Current methods for welding-fume aerosol exposures do not differentiate between the nano-fraction and the larger particles. The objectives of this work are to establish a method to estimate the respiratory deposition of the nano-fraction of selected metals in welding fumes and test this method in a laboratory setting. Manganese (Mn), Nickel (Ni), Chromium (Cr), and hexavalent chromium (Cr(VI)) are commonly found in welding fume aerosols and have been linked with severe adverse health outcomes. Inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) were evaluated as methods for analyzing the content of Mn, Ni, Cr, and Cr(VI) nanoparticles in welding fumes collected with nanoparticle respiratory deposition (NRD) samplers. NRD samplers collect nanoparticles at deposition efficiencies that closely resemble physiological deposition in the respiratory tract. The limits of detection (LODs) and quantitation (LOQs) for ICP-MS and IC were determined analytically. Mild and stainless steel welding fumes generated with a robotic welder were collected with NRD samplers inside a chamber. LODs (LOQs) for Mn, Ni, Cr, and Cr(VI) were 1.3 μg (4.43 μg), 0.4 μg (1.14 μg), 1.1 μg (3.33 μg), and 0.4 μg (1.42 μg), respectively. Recovery of spiked samples and certified welding fume reference material was greater than 95%. When testing the method, the average percentage of total mass concentrations collected by the NRD samplers was ~30% for Mn, ~50% for Cr, and ~60% for Ni, indicating that a large fraction of the metals may lie in the nanoparticle fraction. This knowledge is critical to the development of toxicological studies aimed at finding links between exposure to welding fume nanoparticles and adverse health effects. Future work will involve the validation of the method in workplace settings. [Supplementary materials are available for this article. Go to the publisher’s online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: Digestion, extraction, and analysis procedures for nylon mesh screens.] PMID:24824154

A novel method for assessing respiratory deposition of welding fume nanoparticles.

PubMed

Cena, L G; Keane, M J; Chisholm, W P; Stone, S; Harper, M; Chen, B T

2014-01-01

Welders are exposed to high concentrations of nanoparticles. Compared to larger particles, nanoparticles have been associated with more toxic effects at the cellular level, including the generation of more reactive oxygen species activity. Current methods for welding-fume aerosol exposures do not differentiate between the nano-fraction and the larger particles. The objectives of this work are to establish a method to estimate the respiratory deposition of the nano-fraction of selected metals in welding fumes and test this method in a laboratory setting. Manganese (Mn), Nickel (Ni), Chromium (Cr), and hexavalent chromium (Cr(VI)) are commonly found in welding fume aerosols and have been linked with severe adverse health outcomes. Inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) were evaluated as methods for analyzing the content of Mn, Ni, Cr, and Cr(VI) nanoparticles in welding fumes collected with nanoparticle respiratory deposition (NRD) samplers. NRD samplers collect nanoparticles at deposition efficiencies that closely resemble physiological deposition in the respiratory tract. The limits of detection (LODs) and quantitation (LOQs) for ICP-MS and IC were determined analytically. Mild and stainless steel welding fumes generated with a robotic welder were collected with NRD samplers inside a chamber. LODs (LOQs) for Mn, Ni, Cr, and Cr(VI) were 1.3 μg (4.43 μg), 0.4 μg (1.14 μg), 1.1 μg (3.33 μg), and 0.4 μg (1.42 μg), respectively. Recovery of spiked samples and certified welding fume reference material was greater than 95%. When testing the method, the average percentage of total mass concentrations collected by the NRD samplers was ~30% for Mn, ~50% for Cr, and ~60% for Ni, indicating that a large fraction of the metals may lie in the nanoparticle fraction. This knowledge is critical to the development of toxicological studies aimed at finding links between exposure to welding fume nanoparticles and adverse health effects. Future work will involve the validation of the method in workplace settings. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: Digestion, extraction, and analysis procedures for nylon mesh screens.].

Gene expression profiling in rat kidney after intratracheal exposure to cadmium-doped nanoparticles

NASA Astrophysics Data System (ADS)

Coccini, Teresa; Roda, Elisa; Fabbri, Marco; Sacco, Maria Grazia; Gribaldo, Laura; Manzo, Luigi

2012-08-01

While nephrotoxicity of cadmium is well documented, very limited information exists on renal effects of exposure to cadmium-containing nanomaterials. In this work, "omics" methodologies have been used to assess the action of cadmium-containing silica nanoparticles (Cd-SiNPs) in the kidney of Sprague-Dawley rats exposed intratracheally. Groups of animals received a single dose of Cd-SiNPs (1 mg/rat), CdCl2 (400 μg/rat) or 0.1 ml saline (control). Renal gene expression was evaluated 7 and 30 days post exposure by DNA microarray technology using the Agilent Whole Rat Genome Microarray 4x44K. Gene modulating effects were observed in kidney at both time periods after treatment with Cd-SiNPs. The number of differentially expressed genes being 139 and 153 at the post exposure days 7 and 30, respectively. Renal gene expression changes were also observed in the kidney of CdCl2-treated rats with a total of 253 and 70 probes modulated at 7 and 30 days, respectively. Analysis of renal gene expression profiles at day 7 indicated in both Cd-SiNP and CdCl2 groups downregulation of several cluster genes linked to immune function, oxidative stress, and inflammation processes. Differing from day 7, the majority of cluster gene categories modified by nanoparticles in kidney 30 days after dosing were genes implicated in cell regulation and apoptosis. Modest renal gene expression changes were observed at day 30 in rats treated with CdCl2. These results indicate that kidney may be a susceptible target for subtle long-lasting molecular alterations produced by cadmium nanoparticles locally instilled in the lung.

Nanomaterial Solutions for the Protection of Insulin Producing Beta Cells

NASA Astrophysics Data System (ADS)

Atchison, Nicole Ann

Islet transplantation is a promising treatment for type 1 diabetes. However, even with the many successes, islet transplantation has yet to reach its full potential. Limited islet sources, loss of cell viability during isolation and culture, and post-transplant graft loss are a few of the issues preventing extensive use of islet transplantation. The application of biomaterial systems to alleviate some of the stresses affecting islet viability has led to improvements in isolation and transplantation outcomes, but problems persist. In this work we approach two distinct issues affecting islet viability; ischemic conditions and immunological attack post-transplant. Ischemic conditions have been linked to a loss of islet graft function and occur during organ preservation, islet isolation and culture, and after islets are transplanted. We show that liposomal delivery of adenosine triphosphate (ATP) to beta cells can limit cell death and loss of function in ischemic conditions. We demonstrate that by functionalizing liposomes with the fibronectin-mimetic peptide PR_b, delivery of liposomes to porcine islets and rat beta cells is increased compared to nontargeted controls. Additionally, liposomes are shown to protect by providing both ATP and lipids to the ischemic cells. The delivery of ATP was investigated here but application of PR_b functionalized liposomes could be extended to other interesting cargos as well. The second area of investigation involves encapsulation of islets with silica nanoparticles to create a permselective barrier. Silica nanoparticles are an interesting material for encapsulation given their ability to be fine-tuned and further functionalized. We demonstrate that size-tunable, fluorescent silica nanoparticles can be assembled layer-by-layer on the surface of cells and that silica nanoparticle encapsulated islets are able to secrete insulin in response to a glucose challenge.

DNA as a powerful tool for morphology control, spatial positioning, and dynamic assembly of nanoparticles.

PubMed

Tan, Li Huey; Xing, Hang; Lu, Yi

2014-06-17

CONSPECTUS: Several properties of nanomaterials, such as morphologies (e.g., shapes and surface structures) and distance dependent properties (e.g., plasmonic and quantum confinement effects), make nanomaterials uniquely qualified as potential choices for future applications from catalysis to biomedicine. To realize the full potential of these nanomaterials, it is important to demonstrate fine control of the morphology of individual nanoparticles, as well as precise spatial control of the position, orientation, and distances between multiple nanoparticles. In addition, dynamic control of nanomaterial assembly in response to multiple stimuli, with minimal or no error, and the reversibility of the assemblies are also required. In this Account, we summarize recent progress of using DNA as a powerful programmable tool to realize the above goals. First, inspired by the discovery of genetic codes in biology, we have discovered DNA sequence combinations to control different morphologies of nanoparticles during their growth process and have shown that these effects are synergistic or competitive, depending on the sequence combination. The DNA, which guides the growth of the nanomaterial, is stable and retains its biorecognition ability. Second, by taking advantage of different reactivities of phosphorothioate and phosphodiester backbone, we have placed phosphorothioate at selective positions on different DNA nanostructures including DNA tetrahedrons. Bifunctional linkers have been used to conjugate phosphorothioate on one end and bind nanoparticles or proteins on the other end. In doing so, precise control of distances between two or more nanoparticles or proteins with nanometer resolution can be achieved. Furthermore, by developing facile methods to functionalize two hemispheres of Janus nanoparticles with two different DNA sequences regioselectively, we have demonstrated directional control of nanomaterial assembly, where DNA strands with specific hybridization serve as orthogonal linkers. Third, by using functional DNA that includes DNAzyme, aptamer, and aptazyme, dynamic control of assemblies of gold nanoparticles, quantum dots, carbon nanotubes, and iron oxide nanoparticles in response to one or more stimuli cooperatively have been achieved, resulting in colorimetric, fluorescent, electrochemical, and magnetic resonance signals for a wide range of targets, such as metal ions, small molecules, proteins, and intact cells. Fourth, by mimicking biology, we have employed DNAzymes as proofreading units to remove errors in nanoparticle assembly and further used DNAzyme cascade reactions to modify or repair DNA sequences involved in the assembly. Finally, by taking advantage of different affinities of biotin and desthiobiotin toward streptavidin, we have demonstrated reversible assembly of proteins on DNA origami.

Assembly of metallic nanoparticle arrays on glass via nanoimprinting and thin-film dewetting

PubMed Central

Lee, Sun-Kyu; Hwang, Sori; Kim, Yoon-Kee

2017-01-01

We propose a nanofabrication process to generate large-area arrays of noble metal nanoparticles on glass substrates via nanoimprinting and dewetting of metallic thin films. Glass templates were made via pattern transfer from a topographic Si mold to an inorganically cross-linked sol–gel (IGSG) resist on glass using a two-layer polydimethylsiloxane (PDMS) stamp followed by annealing, which turned the imprinted resist into pure silica. The transparent, topographic glass successfully templated the assembly of Au and Ag nanoparticle arrays via thin-film deposition and dewetting at elevated temperatures. The microstructural and mechanical characteristics that developed during the processes were discussed. The results are promising for low-cost mass fabrication of devices for several photonic applications. PMID:28546899

Assembly of metallic nanoparticle arrays on glass via nanoimprinting and thin-film dewetting.

PubMed

Lee, Sun-Kyu; Hwang, Sori; Kim, Yoon-Kee; Oh, Yong-Jun

2017-01-01

We propose a nanofabrication process to generate large-area arrays of noble metal nanoparticles on glass substrates via nanoimprinting and dewetting of metallic thin films. Glass templates were made via pattern transfer from a topographic Si mold to an inorganically cross-linked sol-gel (IGSG) resist on glass using a two-layer polydimethylsiloxane (PDMS) stamp followed by annealing, which turned the imprinted resist into pure silica. The transparent, topographic glass successfully templated the assembly of Au and Ag nanoparticle arrays via thin-film deposition and dewetting at elevated temperatures. The microstructural and mechanical characteristics that developed during the processes were discussed. The results are promising for low-cost mass fabrication of devices for several photonic applications.

Low-power upconversion in dye-doped polymer nanoparticles.

PubMed

Simon, Yoan C; Bai, Shuo; Sing, Michelle K; Dietsch, Hervé; Achermann, Marc; Weder, Christoph

2012-04-13

Examples of nanoscale low-power upconverting systems are rapidly increasing because of their potential application in numerous areas such as bioimaging or drug delivery. The fabrication of dye-doped cross-linked rubbery nanoparticles that exhibit upconversion even at relatively low power densities is reported here. The nanoparticles were prepared by surfactant-free emulsion polymerization of n-butylacrylate with divinylbenzene as a cross-linker, followed by dyeing of the resulting particles with a two-chromophore system composed of a palladium porphyrin sensitizer, and diphenylanthracene. Blue emission (≈440 nm) of these systems was observed upon excitation at 532 nm. In addition to their optical properties, the particles were characterized by electron microscopy and dynamic light scattering. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electromagnetic Nanoparticles for Sensing and Medical Diagnostic Applications

PubMed Central

Vegni, Lucio

2018-01-01

A modeling and design approach is proposed for nanoparticle-based electromagnetic devices. First, the structure properties were analytically studied using Maxwell’s equations. The method provides us a robust link between nanoparticles electromagnetic response (amplitude and phase) and their geometrical characteristics (shape, geometry, and dimensions). Secondly, new designs based on “metamaterial” concept are proposed, demonstrating great performances in terms of wide-angle range functionality and multi/wide behavior, compared to conventional devices working at the same frequencies. The approach offers potential applications to build-up new advanced platforms for sensing and medical diagnostics. Therefore, in the final part of the article, some practical examples are reported such as cancer detection, water content measurements, chemical analysis, glucose concentration measurements and blood diseases monitoring. PMID:29652853

Fungal cell wall polymer based nanoparticles in protection of tomato plants from wilt disease caused by Fusarium oxysporum f.sp. lycopersici.

PubMed

Sathiyabama, M; Charles, R Einstein

2015-11-20

Cell wall polymer (chitosan) was isolated from Fusarium oxysporum f.sp. lycopersici. They were cross linked with sodium tripolyphosphate (TPP) to synthesize nanoparticles (CWP-NP). The nanoparticles were characterized by FTIR, DLS, SEM, XRD and NMR analyses. The isolated CWP-NP exhibit antifungal activity under in vitro condition. The foliar application of the CWP-NP to tomato plants challenged with F. oxysporum f. sp. lycopersici showed delay in wilt disease symptom expression and reduce the wilt disease severity. Treated plants also showed enhanced yield. These results suggested the role of the CWP-NP in protecting tomato plants from F. oxysporum f.sp. lycopersici infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nanoparticles for Biomedical Imaging

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

Nune, Satish K.; Gunda, Padmaja; Thallapally, Praveen K.

2009-11-01

Background: Synthetic nanoparticles are emerging as versatile tools in biomedical applications, particularly in the area of biomedical imaging. Nanoparticles 1 to 100 nm in diameter possess dimensions comparable to biological functional units. Diverse surface chemistries, unique magnetic properties, tunable absorption and emission properties, and recent advances in the synthesis and engineering of various nanoparticles suggest their potential as probes for early detection of diseases such as cancer. Surface functionalization has further expanded the potential of nanoparticles as probes for molecular imaging. Objective: To summarize emerging research of nanoparticles for biomedical imaging with increased selectivity and reduced non-specific uptake with increasedmore » spatial resolution containing stabilizers conjugated with targeting ligands. Methods: This review summarizes recent technological advances in the synthesis of various nanoparticle probes, and surveys methods to improve the targeting of nanoparticles for their applications in biomedical imaging. Conclusion: Structural design of nanomaterials for biomedical imaging continues to expand and diversify. Synthetic methods have aimed to control the size and surface characteristics of nanoparticles to control distribution, half-life and elimination. Although molecular imaging applications using nanoparticles are advancing into clinical applications, challenges such as storage stability and long-term toxicology should continue to be addressed. Keywords: nanoparticle synthesis, surface modification, targeting, molecular imaging, and biomedical imaging.« less

Controllable synthesis of a novel magnetic core-shell nanoparticle for dual-modal imaging and pH-responsive drug delivery

NASA Astrophysics Data System (ADS)

Xu, Chen; Zhang, Cheng; Wang, Yingxi; Li, Liu; Li, Ling; Whittaker, Andrew K.

2017-12-01

In this study, novel magnetic core-shell nanoparticles Fe3O4@La-BTC/GO have been synthesized by the layer-by-layer self-assembly (LBL) method and further modified by attachment of amino-modified PEG chains. The nanoparticles were thoroughly characterized by x-ray diffraction, FTIR, scanning electron microscopy and transmission electron microscopy. The core-shell structure was shown to be controlled by the LBL method. The drug loading of doxorubicin (DOX) within the Fe3O4@La-BTC/GO-PEG nanoparticles with different numbers of deposited layers was investigated. It was found that DOX loading increased with increasing number of metal organic framework coating layers, indicating that the drug loading can be controlled through the controllable LBL method. Cytotoxicity assays indicated that the Fe3O4@La-BTC/GO-PEG nanoparticles were biocompatible. The DOX was released rapidly at pH 3.8 and pH 5.8, but at pH 7.4 the rate and extent of release was greatly attenuated. The nanoparticles therefore demonstrate an excellent pH-triggered drug release. In addition, the particles could be tracked by magnetic resonance imaging (MRI) and fluorescence optical imaging (FOI). A clear dose-dependent contrast enhancement in T 2-weighted MR images and fluorescence images indicate the potential of these nanoparticles as dual-mode MRI/FOI contrast agents.

TiO2 nanocomposite for the controlled release of drugs against pathogens causing wound infections

NASA Astrophysics Data System (ADS)

Devanand Venkatasubbu, G.; Nagamuthu, S.; Anusuya, T.; Kumar, J.; Chelliah, Ramachandran; Rani Ramakrishnan, Sudha; Antony, Usha; Khan, Imran; Oh, Deog-Hwan

2018-02-01

Chitosan titanium dioxide nanocomposite has been used for wound healing. Titanium dioxide (TiO2) nanoparticles are synthesised and made in to nanocomposite along with chitosan. Curcumin nanoparticles are synthesised. Three different drugs with antimicrobial activity are incorporated into the chitosan/TiO2nanocomposite. Ciprofloxacin, amoxicillin and curcumin nanoparticles are incorporated within the chitosan/TiO2 nanoparticles. The nanoparticles and nanocomposite are characterized with XRD, FTIR, TEM and SEM. Drug loading was found to be around 45% for all the three drug molecules. The drug release profile shows a controlled release of drug molecules from the nanocomposite. Antibacterial studies shows a good inhibition of bacterial species by the nanocomposites.

Toxicity of zero-valent iron nanoparticles to a trichloroethylene-degrading groundwater microbial community.

PubMed

Zabetakis, Kara M; Niño de Guzmán, Gabriela T; Torrents, Alba; Yarwood, Stephanie

2015-01-01

The microbiological impact of zero-valent iron used in the remediation of groundwater was investigated by exposing a trichloroethylene-degrading anaerobic microbial community to two types of iron nanoparticles. Changes in total bacterial and archaeal population numbers were analyzed using qPCR and were compared to results from a blank and negative control to assess for microbial toxicity. Additionally, the results were compared to those of samples exposed to silver nanoparticles and iron filings in an attempt to discern the source of toxicity. Statistical analysis revealed that the three different iron treatments were equally toxic to the total bacteria and archaea populations, as compared with the controls. Conversely, the silver nanoparticles had a limited statistical impact when compared to the controls and increased the microbial populations in some instances. Therefore, the findings suggest that zero-valent iron toxicity does not result from a unique nanoparticle-based effect.

A High-Yield Synthesis of Chalcopyrite CuIn S 2 Nanoparticles with Exceptional Size Control

DOE PAGES

Sun, Chivin; Gardner, Joseph S.; Shurdha, Endrit; ...

2009-01-01

We repormore » t high-yield and efficient size-controlled syntheses of Chalcopyrite CuIn S 2 nanoparticles by decomposing molecular single source precursors (SSPs) via microwave irradiation in the presence of 1,2-ethanedithiol at reaction temperatures as low as 100 ° C and times as short as 30 minutes. The nanoparticles sizes were 1.8 nm to 10.8 nm as reaction temperatures were varied from 100 ° C to 200 ° C with the bandgaps from 2.71 eV to 1.28 eV with good size control and high yields (64%–95%). The resulting nanoparticles were analyzed by XRD, UV-Vis, ICP-OES, XPS, SEM, EDS, and HRTEM. Titration studies by 1 H NMR using SSP 1 with 1,2-ethanedithiol and benzyl mercaptan were conducted to elucidate the formation of Chalcopyrite CuIn S 2 nanoparticles.« less

Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope

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

Abellan Baeza, Patricia; Parent, Lucas R.; Al Hasan, Naila M.

2016-01-07

Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale. In this work we synthesize Pd nanoparticles with well-controlled size using in situ liquid-stage scanning transmission electron microscopy (STEM) and demonstrate a match between the reaction kinetics and products of the radiolytic and chemical syntheses of size-stabilized Pd nanoparticles. We quantify the effect of electron dose on the nucleation kinetics, and compare these results with in situ small angle X-ray scattering (SAXS) experiments investigating the effect of temperature during chemical synthesis. This work introduces methods for precisemore » control of nanoparticle synthesis in the STEM and provides a means to uncover the fundamental processes behind the size and shape stabilization of nanoparticles.« less

Green synthesis of silver nanoparticles for the control of mosquito vectors of malaria, filariasis, and dengue

USDA-ARS?s Scientific Manuscript database

A biological method was used to synthesize stable silver nanoparticles. The nanoparticles were tested as larvicides against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Annona squamosa leaf broth (5%) reduced aqueous AgNO3 to stable silver nanoparticles with average particle siz...

Gold surfaces and nanoparticles are protected by Au(0)-thiyl species and are destroyed when Au(I)-thiolates form.

PubMed

Reimers, Jeffrey R; Ford, Michael J; Halder, Arnab; Ulstrup, Jens; Hush, Noel S

2016-03-15

The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)-thiyl, with Au(I)-thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)-thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s-d hybridization and charge polarization effects that perturbatively mix in some Au(I)-thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)-thiolate involvement. Predictions that Brust-Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)-thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established.

Gold surfaces and nanoparticles are protected by Au(0)–thiyl species and are destroyed when Au(I)–thiolates form

PubMed Central

Reimers, Jeffrey R.; Ford, Michael J.; Halder, Arnab; Ulstrup, Jens; Hush, Noel S.

2016-01-01

The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)–thiyl, with Au(I)–thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)–thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s–d hybridization and charge polarization effects that perturbatively mix in some Au(I)–thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)–thiolate involvement. Predictions that Brust–Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)–thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established. PMID:26929334

Experimental Aspects of Colloidal Interactions in Mixed Systems of Liposome and Inorganic Nanoparticle and Their Applications

PubMed Central

Michel*, Raphael; Gradzielski*, Michael

2012-01-01

In the past few years, growing attention has been devoted to the study of the interactions taking place in mixed systems of phospholipid membranes (for instance in the form of vesicles) and hard nanoparticles (NPs). In this context liposomes (vesicles) may serve as versatile carriers or as a model system for biological membranes. Research on these systems has led to the observation of novel hybrid structures whose morphology strongly depends on the charge, composition and size of the interacting colloidal species as well as on the nature (pH, ionic strength) of their dispersing medium. A central role is played by the phase behaviour of phospholipid bilayers which have a tremendous influence on the liposome properties. Another central aspect is the incorporation of nanoparticles into vesicles, which is intimately linked to the conditions required for transporting a nanoparticle through a membrane. Herein, we review recent progress made on the investigations of the interactions in liposome/nanoparticle systems focusing on the particularly interesting structures that are formed in these hybrid systems as well as their potential applications. PMID:23109874

Formation and Characterization of Silver Nanoparticle Composite with Poly(p-Br/F-phenylsilane).

PubMed

Roh, Sung-Hee; Noh, Ji Eun; Woo, Hee-Gweon; Cho, Myong-Shik; Sohn, Honglae

2015-02-01

The one-pot production and structural characterization of composites of silver nanoparticles with poly(p-Br/F-phenylsilane), Br/F-PPS, have been performed. The conversion of Ag+ ions to stable Ag0 nanoparticles is mediated by the copolymer Br/F-PPS having both possibly reactive Si-H bonds in the polymer backbone and C-Br bonds in the substituents along with relatively inert C-F bonds. Transmission electron microscopy and field emission scanning electron microscopy analyses show the formation of the composites where silver nanoparticles (less than 30 nm of size) are well dispersed over the Br/F-PPS matrix. X-ray diffraction patterns are consistent with that for face-centered-cubic typed silver. The polymer solubility in toluene implys that the cleavage of C-Br bond and the Si-F dative bonding may not be occurred appreciably at ambient temperature. Nonetheless, thermogravimetric analysis data suggest that some sort of cross-linking could take place at high temperature. Most of the silver particles undergo macroscopic aggregation without Br/F-PPS, which indicates that the polysilane is necessary for stabilizing the silver nanoparticles.

Liquid-Crystalline Elastomers with Gold Nanoparticle Cross-Linkers.

PubMed

Wójcik, Michał M; Wróbel, Jarosław; Jańczuk, Zuzanna Z; Mieczkowski, Józef; Górecka, Ewa; Choi, Joonmyung; Cho, Maenghyo; Pociecha, Damian

2017-07-03

Embedding nanoparticles in a responsive polymer matrix is a formidable way to fabricate hybrid materials with predesigned properties and prospective applications in actuators, mechanically tunable optical elements, and electroclinic films. However, achieving chemical compatibility between nanoparticles and organic matter is not trivial and often results in disordered structures. Herein, it is shown that using nanoparticles as exclusive cross-linkers in the preparation of liquid-crystalline polymers can yield long-range-ordered liquid-crystalline elastomers with high loadings of well-dispersed nanoparticles, as confirmed by small-angle XRD measurements. Moreover, the strategy of incorporating NPs as cross-linking units does not result in disruption of mechanical properties of the polymer, and this phenomenon was explained by the means of all-atom molecular dynamics simulations. Such materials can exhibit switchable behavior under thermal stimulus with stability spanning over multiple heating/cooling cycles. The presented strategy has proven to be a promising approach for the preparation of new types of hybrid liquid-crystalline elastomers that can be of value for future photonic applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Attenuation of corneal myofibroblast development through nanoparticle-mediated soluble transforming growth factor-β type II receptor (sTGFβRII) gene transfer.

PubMed

Sharma, Ajay; Rodier, Jason T; Tandon, Ashish; Klibanov, Alexander M; Mohan, Rajiv R

2012-01-01

To explore (i) the potential of polyethylenimine (PEI)-DNA nanoparticles as a vector for delivering genes into human corneal fibroblasts, and (ii) whether the nanoparticle-mediated soluble extracellular domain of the transforming growth factor-β type II receptor (sTGFβRII) gene therapy could be used to reduce myofibroblasts and fibrosis in the cornea using an in vitro model. PEI-DNA nanoparticles were prepared at a nitrogen-to-phosphate ratio of 30 by mixing linear PEI and a plasmid encoding sTGFβRII conjugated to the fragment crystallizable (Fc) portion of human immunoglobulin. The PEI-DNA polyplex formation was confirmed through gel retardation assay. Human corneal fibroblasts (HCFs) were generated from donor corneas; myofibroblasts and fibrosis were induced with TGFβ1 (1 ng/ml) stimulation employing serum-free conditions. The sTGFβRII conjugated to the Fc portion of human immunoglobulin gene was introduced into HCF using either PEI-DNA nanoparticles or Lipofectamine. Suitable negative and positive controls to compare selected nanoparticle and therapeutic gene efficiency were included. Delivered gene copies and mRNA (mRNA) expression were quantified with real-time quantitative PCR (qPCR) and protein with enzyme-linked immunosorbent assay (ELISA). The changes in fibrosis parameters were quantified by measuring fibrosis marker α-smooth muscle actin (SMA) mRNA and protein levels with qPCR, immunostaining, and immunoblotting. Cytotoxicity was determined using cellular viability, proliferation, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. PEI readily bound to plasmids to form nanoparticular polyplexes and exhibited much greater transfection efficiency (p<0.01) than the commercial reagent Lipofectamine. The PEI-DNA-treated cultures showed 4.5×10(4) plasmid copies/µg DNA in real-time qPCR and 7,030±87 pg/ml sTGFβRII protein in ELISA analyses, whereas Lipofectamine-transfected cultures demonstrated 1.9×10(3) gene copies/µg DNA and 1,640±100 pg/ml sTGFβRII protein during these assays. The PEI-mediated sTGFβRII delivery remarkably attenuated TGFβ1-induced transdifferentiation of corneal fibroblasts to myofibroblasts in cultures, as indicated by threefold lower levels of SMA mRNA (p<0.01) and significant inhibition of SMA protein (up to 96±3%; p<0.001 compared to no-gene-delivered cultures) in immunocytochemical staining and immunoblotting. The nanoparticle-mediated delivery of sTGFβRII showed significantly better antifibrotic effects than the Lipofectamine under similar experimental conditions. However, the inhibition of myofibroblast in HCF cultures by sTGFβRII overexpression by either method was significantly higher than the naked vector transfection. Furthermore, PEI- or Lipofectamine-mediated sTGFβRII delivery into HCF did not alter cellular proliferation or phenotype at 12 and 24 h post-treatment. Nanoparticles treated with HCF showed more than 90% cellular viability and very low cell death (2-6 TUNEL+ cells), suggesting that the tested doses of PEI-nanoparticles do not induce significant cell death. This study demonstrated that PEI-DNA nanoparticles are an attractive vector for the development of nonviral corneal gene therapy approaches and that the sTGFβRII gene delivery into keratocytes could be used to control corneal fibrosis in vivo.

Development of photopolymerizable clay nanocomposites utilizing reactive dispersants

NASA Astrophysics Data System (ADS)

Owusu-Adom, Kwame

Nanocomposites hold tremendous promise for expanding the utility of polymeric materials. However, accessing particulate sizes in the nanoscale domain continues to be a scientific challenge, especially in highly cross-linked photopolymerizable systems. In this study, photopolymerizable nanocomposites utilizing clay nanoparticles and reactive dispersants have been developed. The influence of particle size, dispersant-clay interactions, and surfactant concentration on photopolymerization behavior and nanoparticle dispersion has been elucidated. Clay particles serve as templates upon which surfactants aggregate during photopolymerization. This results in higher photopolymerization rates with addition of increasing concentrations of polymerizable surfactants. Furthermore, polymerizable surfactants induce faster photopolymerization rates compared to non-polymerizable analogues in systems that have ionically-bound dispersants on the particle surface. Utilizing reactive organoclays induces significant changes to the photopolymerization behavior depending on the choice of reactive functionality employed. Faster acrylate photopolymerization rates occur in photopolymer systems containing thiol-modified clays, while much slower rates occur for nonpolymerizable organoclay systems. In addition, chemical compatibility between monomer and clay dispersant (based on chemical similarity or polarity) allows enhancement of exfoliation in photopolymerizable formulations. With polymerizable dispersants, exfoliation is readily achieved in various multifunctional acrylate systems. The degree of exfoliation depends on the position of the reactive group relative to the surfactant's cationic site and the type of functionality. Thiolated organoclays exfoliate during polymerization, while methacrylated clays show substantially less dependence on polymerization behavior. Interestingly, changes in the physical properties of the resulting nanocomposite are independent of the degree of exfoliation in polymerizable organoclay systems. The polymer cross-link density dictates the magnitude of change in both modulus and glass transition temperature of the nanocomposite. Substantial increases in modulus and Tg occur in elastomeric and low cross-link density polymers, while decreases occur in the modulus and Tg of highly cross-linked polymer networks. Finally, these parameters have formed a basis for developing nanocomposites with higher moduli and lower volumetric shrinkage. The photopolymerization rates of these systems are controllable and increase substantially with addition of polymerizable organoclays. Such properties occur in traditional multifunctional acrylate photopolymer systems as well as new binary thiol-(meth)acrylate and ternary thiol-ene-(meth)acrylate photopolymers.

Shaped platinum nanoparticles directly synthesized inside mesoporous silica supports

NASA Astrophysics Data System (ADS)

Kim, Jiwhan; Bae, Youn-Sang; Lee, Hyunjoo

2014-10-01

It is difficult to deposit shape-controlled nanoparticles into a mesoporous framework while preserving the shape. For shaped platinum nanoparticles, which are typically 5-10 nm in size, capillary inclusion by sonication or the formation of a mesoporous framework around the shaped platinum nanoparticles has been attempted, but the nanoparticles aggregated or their shapes were degraded easily. In this work, we directly nucleated platinum on the surface inside a mesoporous silica support and controlled the overgrowth step, producing cubic shaped nanoparticles. Mercaptopropyltrimethoxysilane was used as an anchoring agent causing nucleation at the silica surface, and it also helped to shape the nanoparticles. Platinum nanocubes, which were synthesized with polymeric capping agents separately, were deposited inside the mesoporous silica by sonication, but most of the nanoparticles were clogged at the entrance to the pores, and the surface of the platinum had very few sites that were catalytically active, as evidenced by the small H2 uptake. Unshaped platinum nanoparticles, which were prepared by conventional wet impregnation, showed a similar amount of H2 uptake as the in situ shaped platinum cubes, but the selectivity for pyrrole hydrogenation was poorer towards the production of pyrrolidine. The mesoporosity and the residual thiol groups on the surface of the in situ shaped Pt nanocubes might cause a high selectivity for pyrrolidine.It is difficult to deposit shape-controlled nanoparticles into a mesoporous framework while preserving the shape. For shaped platinum nanoparticles, which are typically 5-10 nm in size, capillary inclusion by sonication or the formation of a mesoporous framework around the shaped platinum nanoparticles has been attempted, but the nanoparticles aggregated or their shapes were degraded easily. In this work, we directly nucleated platinum on the surface inside a mesoporous silica support and controlled the overgrowth step, producing cubic shaped nanoparticles. Mercaptopropyltrimethoxysilane was used as an anchoring agent causing nucleation at the silica surface, and it also helped to shape the nanoparticles. Platinum nanocubes, which were synthesized with polymeric capping agents separately, were deposited inside the mesoporous silica by sonication, but most of the nanoparticles were clogged at the entrance to the pores, and the surface of the platinum had very few sites that were catalytically active, as evidenced by the small H2 uptake. Unshaped platinum nanoparticles, which were prepared by conventional wet impregnation, showed a similar amount of H2 uptake as the in situ shaped platinum cubes, but the selectivity for pyrrole hydrogenation was poorer towards the production of pyrrolidine. The mesoporosity and the residual thiol groups on the surface of the in situ shaped Pt nanocubes might cause a high selectivity for pyrrolidine. Electronic supplementary information (ESI) available: Fig. S1-S9. See DOI: 10.1039/c4nr03951c

Soft Landing of Bare Nanoparticles with Controlled Size, Composition, and Morphology

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

Johnson, Grant E.; Colby, Robert J.; Laskin, Julia

2015-01-01

A kinetically-limited physical synthesis method based on magnetron sputtering and gas aggregation has been coupled with size-selection and ion soft landing to prepare bare metal nanoparticles on surfaces with controlled coverage, size, composition, and morphology. Employing atomic force microscopy (AFM) and scanning electron microscopy (SEM), it is demonstrated that the size and coverage of bare nanoparticles soft landed onto flat glassy carbon and silicon as well as stepped graphite surfaces may be controlled through size-selection with a quadrupole mass filter and the length of deposition, respectively. The bare nanoparticles are observed with AFM to bind randomly to the flat glassymore » carbon surface when soft landed at relatively low coverage (1012 ions). In contrast, on stepped graphite surfaces at intermediate coverage (1013 ions) the soft landed nanoparticles are shown to bind preferentially along step edges forming extended linear chains of particles. At the highest coverage (5 x 1013 ions) examined in this study the nanoparticles are demonstrated with both AFM and SEM to form a continuous film on flat glassy carbon and silicon surfaces. On a graphite surface with defects, however, it is shown with SEM that the presence of localized surface imperfections results in agglomeration of nanoparticles onto these features and the formation of neighboring depletion zones that are devoid of particles. Employing high resolution scanning transmission electron microscopy in the high angular annular dark field imaging mode (STEM-HAADF) and electron energy loss spectroscopy (EELS) it is demonstrated that the magnetron sputtering/gas aggregation synthesis technique produces single metal particles with controlled morphology as well as bimetallic alloy nanoparticles with clearly defined core-shell structure. Therefore, this kinetically-limited physical synthesis technique, when combined with ion soft landing, is a versatile complementary method for preparing a wide range of bare supported nanoparticles with selected properties that are free of the solvent, organic capping agents, and residual reactants present with nanoparticles synthesized in solution.« less

An electrochemiluminescence sensor based on a Ru(bpy)3(2+)-silica-chitosan/nanogold composite film.

PubMed

Cai, Zhi-min; Wu, Yan-fang; Huang, Yun-he; Li, Qiu-ping; Chen, Xiao-mei; Chen, Xi

2012-05-30

Chitosan, a cationic polysaccharide containing amino and hydroxyl groups, was used to fabricate an electrochemiluminescence (ECL) sensor. In the sensor construction, a glassy carbon electrode (GCE) was first coated by a chitosan film which embedded gold nanoparticles, and then the film was modified by introducing carboxyl groups on the surface, which were used to immobilize tris(2,2'-bipyridyl)ruthenium(II) doped amino-functional silica nanoparticles (NH(2)-RuSiNPs) through amido links. The successful modification was confirmed by scanning electronic microscopy and cyclic voltammetry. A binding model between the chitosan/nanogold composite film and NH(2)-RuSiNPs was also proposed, in which the amido link was the dominant bonding, accompanied with hydrogen bond interaction. ECL studies revealed that the sensor had very good response to different concentrations of 2-(dibutylamino) ethanol. This sensor was also applied in methamphetamine determination. Copyright © 2012 Elsevier B.V. All rights reserved.

Histidine-functionalized water-soluble nanoparticles for biomimetic nucleophilic/general-base catalysis under acidic conditions.

PubMed

Chadha, Geetika; Zhao, Yan

2013-10-21

Cross-linking the micelles of 4-dodecyloxybenzyltripropargylammonium bromide by 1,4-diazidobutane-2,3-diol in the presence of azide-functionalized imidazole derivatives yielded surface-cross-linked micelles (SCMs) with imidazole groups on the surface. The resulting water-soluble nanoparticles were found, by fluorescence spectroscopy, to contain hydrophobic binding sites. The imidazole groups promoted the photo-deprotonation of 2-naphthol at pH 6 and catalyzed the hydrolysis of p-nitrophenylacetate (PNPA) in aqueous solution at pH ≥ 4. Although the overall hydrolysis rate slowed down with decreasing solution pH, the catalytic effect of the imidazole became stronger because the reactions catalyzed by unfunctionalized SCMs slowed down much more. The unusual ability of the imidazole–SCMs to catalyze the hydrolysis of PNPA under acidic conditions was attributed to the local hydrophobicity and the positive nature of the SCMs.

Polymer Nanocomposites: Insights from Theory and Molecular Simulations

NASA Astrophysics Data System (ADS)

Pani, Rakhee

Advantages of polymer nanocomposites have attracted great industrial attention due to their multifunctionality and innovative technological properties. Addition of small amount of nanoparticle (nanospheres, nanotubes, nanorods, nanoplatelets, or sheets) to polymer matrix cause dramatic improvement in structural and functional properties, which is difficult to attain from those of individual components. The interaction between polymer and nanoparticle create bulk materials dominated by solid state physics at the nanoscale. Furthermore, morphology of nanocomposites depends on structural arrangements of nanoparticles. Thus, for achievement of optimized functionality like electrical, optical, mechanical and thermal properties control over the dispersion of the nanoparticle is essential. However, properties of polymer nanocomposites depend on morphology control and nature of interfacial interactions. In order to control the morphology it is necessary to understand how the processing conditions, shape and size of nanoparticle influence the structure of composite. Molecular simulations can help us to predict the parameters that control the structural changes and we could design polymer nanocomposite entailing their end-use. In this work, we addressed the following research questions: (1) the dependence of nanoparticle ligand corona structure on solvent quality and (2) the role of interfacial energy and interactions on the dispersion of molecules and nanoparticles. Specifically, this research assessed the effect of solvent interactions on the structure of nanoparticles on the example of redox core encapsulating dendrimer and ligand functionalized gold nanoparticles, role of chemical interaction on solubility of glucose in ionic liquids, diffusion of fullerene nanoparticles in polymer matrix and influence of solubility parameters on the compatibility of gold nanoparticles with diblock copolymers. Computational methods allow quantifying the structure and flexibility of the polymer chains, how energetics and surface tension change with chemical composition of the polymer/dendrimer blocks, influence of nanoparticle on structural properties of polymer and factors which may contribute to the phase separation of the polymer from nanoparticle. Interfacial characteristics are not only determined by the size-induced properties, but also the surface chemistry of the particles. Presence of solvent and the resultant interactions with the solvent are known to influence the morphology and prevent or induce aggregation of nanoparticles in polymers. We found that surface chemistry can induce change in the structure of dendrimers encapsulating a redox active core and change the solubility of the nanoparticles. The interactions between nanoparticles and polymers can also influence the morphology. We performed investigation on the role of orientation of fullerene derivatives and surface energy of polymer surface which may induce the aggregation of the fullerene nanoparticles. Furthermore, we used quantitative measurements like cluster analysis to understand the most probable orientation of the fullerene derivative with respect to the polymer chains and the diffusion of the fullerene nanoparticle, which is related to the efficiency of solar cells, can change on presence of regiorandom and regioregular polymer chains. Furthermore, we have also used different solvents based on their Hildebrand solubility parameters to investigate factors governing the morphology of polymer nanocomposite via solvent interactions. We showed that change in solvent interactions affect the compatibility, aggregation/dispersion of the gold nanoparticles, which will directly affect the morphology of polymer matrix and structural aspects which can impact their functionality. Overall, our research indicated that solvent interaction play a role in controlling the morphology of polymer nanocomposite and solubility parameter can help us to predict the resulting morphology.

Green Synthesis of Silver Nanoparticles from Botanical Sources and Their Use for Control of Medical Insects and Malaria Parasites

USDA-ARS?s Scientific Manuscript database

The use of "green" processes for the synthesis of nanoparticles is a new branch of nanotechnology. However, knowledge of the bioactivity of nanoparticles against mosquitoes and malaria parasites is limited. We tested silver nanoparticles (average size 450 nm) bio-reduced in 5% Cassia occidentalis ...

Green synthesis of Au nanoparticles using potato extract: stability and growth mechanism

NASA Astrophysics Data System (ADS)

Castillo-López, D. N.; Pal, U.

2014-08-01

We report on the synthesis of spherical, well-dispersed colloidal gold nanoparticles of 17.5-23.5 nm average sizes in water using potato extract (PE) both as reducing and stabilizing agent. The effects of PE content and the pH value of the reaction mixture have been studied. Formation and growth dynamics of the Au nanoparticles in the colloids were studied using transmission electron microscopy and UV-Vis optical absorption spectroscopy techniques. While the reductor content and, hence, the nucleation and growth rates of the nanoparticles could be controlled by controlling the PE content in the reaction solution, the stability of the nanoparticles depended strongly on the pH of the reaction mixture. The mechanisms of Au ion reduction and stabilization of Au nanoparticles by potato starch have been discussed. The use of common natural solvent like water and biological reductor like PE in our synthesis process opens up the possibility of synthesizing Au nanoparticles in fully green (environmental friendly) way, and the Au nanoparticles produced in such way should have good biocompatibility.

Size-controlled green synthesis of silver nanoparticles mediated by gum ghatti (Anogeissus latifolia) and its biological activity

PubMed Central

2012-01-01

Background Gum ghatti is a proteinaceous edible, exudate tree gum of India and is also used in traditional medicine. A facile and ecofriendly green method has been developed for the synthesis of silver nanoparticles from silver nitrate using gum ghatti (Anogeissus latifolia) as a reducing and stabilizing agent. The influence of concentration of gum and reaction time on the synthesis of nanoparticles was studied. UV–visible spectroscopy, transmission electron microscopy and X-ray diffraction analytical techniques were used to characterize the synthesized nanoparticles. Results By optimizing the reaction conditions, we could achieve nearly monodispersed and size controlled spherical nanoparticles of around 5.7 ± 0.2 nm. A possible mechanism involved in the reduction and stabilization of nanoparticles has been investigated using Fourier transform infrared spectroscopy and Raman spectroscopy. Conclusions The synthesized silver nanoparticles had significant antibacterial action on both the Gram classes of bacteria. As the silver nanoparticles are encapsulated with functional group rich gum, they can be easily integrated for various biological applications. PMID:22571686

Nanoparticle-based Therapies for Wound Biofilm Infection: Opportunities and Challenges

PubMed Central

Kim, Min-Ho

2016-01-01

Clinical data from human chronic wounds implicates biofilm formation with the onset of wound chronicity. Despite the development of novel antimicrobial agents, the cost and complexity of treating chronic wound infections associated with biofilms remain a serious challenge, which necessitates the development of new and alternative approaches for effective anti-biofilm treatment. Recent advancement in nanotechnology for developing a new class of nanoparticles that exhibit unique chemical and physical properties holds promise for the treatment of biofilm infections. Over the last decade, nanoparticle-based approaches against wound biofilm infection have been directed toward developing nanoparticles with intrinsic antimicrobial properties, utilizing nanoparticles for controlled antimicrobials delivery, and applying nanoparticles for antibacterial hyperthermia therapy. In addition, a strategy to functionalize nanoparticles towards enhanced penetration through the biofilm matrix has been receiving considerable interest recently by means of achieving an efficient targeting to the bacterial cells within biofilm matrix. This review summarizes and highlights the recent development of these nanoparticle-based approaches as potential therapeutics for controlling wound biofilm infection, along with current challenges that need to be overcome for their successful clinical translation. PMID:26955044

Microfluidic magnetic switching valves based on aggregates of magnetic nanoparticles: Effects of aggregate length and nanoparticle sizes

NASA Astrophysics Data System (ADS)

Jiemsakul, Thanakorn; Manakasettharn, Supone; Kanharattanachai, Sivakorn; Wanna, Yongyuth; Wangsuya, Sujint; Pratontep, Sirapat

2017-01-01

We demonstrate microfluidic switching valves using magnetic nanoparticles blended within the working fluid as an alternative microfluidic flow control in microchannels. Y-shaped microchannels have been fabricated by using a CO2 laser cutter to pattern microchannels on transparent poly(methyl methacrylate) (PMMA) sheets covered with thermally bonded transparent polyvinyl chloride (PVC) sheets. To examine the performance of the microfluidic magnetic switching valves, an aqueous magnetic nanoparticle suspension was injected into the microchannels by a syringe pump. Neodymium magnets were then employed to attract magnetic nanoparticles and form an aggregate that blocked the microchannels at a required position. We have found that the maximum volumetric flow rate of the syringe pump that the magnetic nanoparticle aggregate can withstand scales with the square of the external magnetic flux density. The viscosity of the fluid exhibits dependent on the aggregate length and the size of the magnetic nanoparticles. This microfluidic switching valve based on aggregates of magnetic nanoparticles has strong potentials as an on-demand flow control, which may help simplifying microfluidic channel designs.

Mechanical control of the plasmon coupling with Au nanoparticle arrays fixed on the elastomeric film via chemical bond

NASA Astrophysics Data System (ADS)

Bedogni, Elena; Kaneko, Satoshi; Fujii, Shintaro; Kiguchi, Manabu

2017-03-01

We have fabricated Au nanoparticle arrays on the flexible poly(dimethylsiloxane) (PDMS) film. The nanoparticles were bound to the film via a covalent bond by a ligand exchange reaction. Thanks to the strong chemical bonding, highly stable and uniformly dispersed Au nanoparticle arrays were fixed on the PDMS film. The Au nanoparticle arrays were characterized by the UV-vis, scanning electron microscope (SEM) and surface enhanced Raman scattering (SERS). The UV-vis and SEM measurements showed the uniformity of the surface-dispersed Au nanoparticles, and SERS measurement confirmed the chemistry of the PDMS film. Reflecting the high stability and the uniformity of the Au nanoparticle arrays, the plasmon wavelength of the Au nanoparticles reversely changed with modulation of the interparticle distance, which was induced by the stretching of the PDMS film. The plasmon wavelength linearly decreased from 664 to 591 nm by stretching of 60%. The plasmon wavelength shift can be explained by the change in the strength of the plasmon coupling which is mechanically controlled by the mechanical strain.

Microfluidic Reactors for the Controlled Synthesis of Nanoparticles

NASA Astrophysics Data System (ADS)

Erdem, Emine Yegan

Nanoparticles have attracted a lot of attention in the past few decades due to their unique, size-dependent properties. In order to use these nanoparticles in devices or sensors effectively, it is important to maintain uniform properties throughout the system; therefore nanoparticles need to have uniform sizes -- or monodisperse. In order to achieve monodispersity, an extreme control over the reaction conditions is required during their synthesis. These reaction conditions such as temperature, concentration of reagents, residence times, etc. affect the structure of nanoparticles dramatically; therefore when the conditions vary locally in the reaction vessel, different sized nanoparticles form, causing polydispersity. In widely-used batch wise synthesis techniques, large sized reaction vessels are used to mix and heat reagents. In these types of systems, it is very hard to avoid thermal gradients and to achieve rapid mixing times as well as to control residence times. Also it is not possible to make rapid changes in the reaction parameters during the synthesis. The other drawback of conventional methods is that it is not possible to separate the nucleation of nanoparticles from their growth; this leads to combined nucleation and growth and subsequently results in polydisperse size distributions. Microfluidics is an alternative method by which the limitations of conventional techniques can be addressed. Due to the small size, it is possible to control temperature and concentration of reagents precisely as well as to make rapid changes in mixing ratios of reagents or temperature of the reaction zones. There have been several microfluidic reactors -- (microreactors) in literature that were designed to improve the size distribution of nanoparticles. In this work, two novel microfluidic systems were developed for achieving controlled synthesis of nanoparticles. The first microreactor was made out of a chemically robust polymer, polyurethane, and it was used for low temperature nanoparticle synthesis. This microreactor was fabricated by using a CO 2-laser printer, which is an inexpensive method for fabricating microfluidic devices and it is a relatively fast way compared to other fabrication techniques. Iron oxide nanoparticle synthesis was demonstrated using this reactor and size distributions with a standard deviation of 10% was obtained. The second microreactor presented in this work was designed to produce monodisperse nanoparticles by utilizing thermally isolated heated and cooled regions for separating nucleation and growth processes. This microreactor was made out of silicon and it was used to demonstrate the synthesis of TiO 2 nanoparticles. Size distributions with less than 10% standard deviation were achieved. This microreactor also provides a platform for studying the effects of temperature and residence times which is very important to understand the reaction kinetics of nanoparticle synthesis. In this work, two microfluidic techniques for retrieving nanoparticles from the microreactors were also discussed. The first method was based on trapping the aqueous droplet phase inside the microchannel and the second method was utilizing a micropost array to direct droplets from the oil solution to the pure water. As a final step, a printing technique was used to print nanoparticles synthesized inside the microreactors for future applications. This ability is important for achieving smart surfaces that can utilize the properties of nanoparticles for sensing applications in the future.

Flash NanoPrecipitation (FNP) for bioengineering nanoparticles to enhance the bioavailability

NASA Astrophysics Data System (ADS)

Feng, Jie; Zhang, Yingyue; McManus, Simone; Prud'Homme, Robert

2017-11-01

Nanoparticles for the delivery of therapeutics have been one of the successful areas in biomedical nanotechnology. Nanoparticles improve bioavailability by 1) the higher surface-to-volume ratios, enhancing dissolution rates, and 2) trapping drug molecules in higher energy, amorphous states for a higher solubility. However, conventional direct precipitation to prepare nanoparticles has the issues of low loading and encapsulation efficiency. Here we demonstrate a kinetically controlled and rapid-precipitation process called Flash NanoPrecipitation (FNP), to offer a multi-phase mixing platform for bioengineering nanoparticles. With the designed geometry in the micro-mixer, we can generate nanoparticles with a narrow size distribution, while maintaining high loading and encapsulation efficiency. By controlling the time scales in FNP, we can tune the nanoparticle size and the robustness of the process. Remarkably, the dissolution rates of the nanoparticles are significantly improved compared with crystalline drug powders. Furthermore, we investigate how to recover the drug-loaded nanoparticles from the aqueous dispersions. Regarding the maintenance of the bioavailability, we discuss the advantages and disadvantages of each drying process. These results suggest that FNP offers a versatile and scalable nano-fabrication platform for biomedical engineering.

Control of viscous fingering by nanoparticles

NASA Astrophysics Data System (ADS)

Sabet, Nasser; Hassanzadeh, Hassan; Abedi, Jalal

2017-12-01

A substantial viscosity increase by the addition of a low dose of nanoparticles to the base fluids can well influence the dynamics of viscous fingering. There is a lack of detailed theoretical studies that address the effect of the presence of nanoparticles on unstable miscible displacements. In this study, the impact of nonreactive nanoparticle presence on the stability and subsequent mixing of an originally unstable binary system is examined using linear stability analysis (LSA) and pseudospectral-based direct numerical simulations (DNS). We have parametrized the role of both nondepositing and depositing nanoparticles on the stability of miscible displacements using the developed static and dynamic parametric analyses. Our results show that nanoparticles have the potential to weaken the instabilities of an originally unstable system. Our LSA and DNS results also reveal that nondepositing nanoparticles can be used to fully stabilize an originally unstable front while depositing particles may act as temporary stabilizers whose influence diminishes in the course of time. In addition, we explain the existing inconsistencies concerning the effect of the nanoparticle diffusion coefficient on the dynamics of the system. This study provides a basis for further research on the application of nanoparticles for control of viscosity-driven instabilities.

Human nitric oxide biomarker as potential NO donor in conjunction with superparamagnetic iron oxide @ gold core shell nanoparticles for cancer therapeutics.

PubMed

Singh, Nimisha; Patel, Khushbu; Sahoo, Suban K; Kumar, Rajender

2018-03-01

Nitric oxide releasing superparamagnetic (Fe 3 O 4 -Au@NTHP) nanoparticles were synthesized by conjugation of human biomarker of nitric oxide, N-nitrosothioproline with iron oxide-gold (Fe 3 O 4 -Au) core shell nanoparticles. The structure and morphology of the prepared nanoparticles were confirmed by ATR-FTIR, HR-TEM, EDAX, XPS, DLS and VSM measurements. N-nitrosothioproline is a natural molecule and nontoxic to humans. Thus, the core shell nanoparticles prepared were highly biocompatible. The prepared Fe 3 O 4 -Au@NTHP nanoparticles also provided an excellent release of nitric oxide in dark and upon light irradiation for cancer treatment. The amount of NO release was controllable with the wavelength of light and time of irradiation. The developed nanoparticles provided efficient cellular uptake and good cytotoxicity in picomolar range when tested on HeLa cancerous cells. These nanoparticles on account of their controllable NO release can also be used to release small amount of NO for killing cancerous cells without any toxic effect. Furthermore, the magnetic and photochemical properties of these nanoparticles provides dual platform for magneto therapy and phototherapy for cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Natural material-decorated mesoporous silica nanoparticle container for multifunctional membrane-controlled targeted drug delivery

PubMed Central

Hu, Yan; Ke, Lei; Chen, Hao; Zhuo, Ma; Yang, Xinzhou; Zhao, Dan; Zeng, Suying; Xiao, Xincai

2017-01-01

To avoid the side effects caused by nonspecific targeting, premature release, weak selectivity, and poor therapeutic efficacy of current nanoparticle-based systems used for drug delivery, we fabricated natural material-decorated nanoparticles as a multifunctional, membrane-controlled targeted drug delivery system. The nanocomposite material coated with a membrane was biocompatible and integrated both specific tumor targeting and responsiveness to stimulation, which improved transmission efficacy and controlled drug release. Mesoporous silica nanoparticles (MSNs), which are known for their biocompatibility and high drug-loading capacity, were selected as a model drug container and carrier. The membrane was established by the polyelectrolyte composite method from chitosan (CS) which was sensitive to the acidic tumor microenvironment, folic acid-modified CS which recognizes the folate receptor expressed on the tumor cell surface, and a CD44 receptor-targeted polysaccharide hyaluronic acid. We characterized the structure of the nanocomposite as well as the drug release behavior under the control of the pH-sensitive membrane switch and evaluated the antitumor efficacy of the system in vitro. Our results provide a basis for the design and fabrication of novel membrane-controlled nanoparticles with improved tumor-targeting therapy. PMID:29200852

Amidase encapsulated O-carboxymethyl chitosan nanoparticles for vaccine delivery.

PubMed

Smitha, K T; Sreelakshmi, M; Nisha, N; Jayakumar, R; Biswas, Raja

2014-02-01

This work reports the development of amidase encapsulated O-carboxymethyl chitosan nanoparticles (Ami-O-CMC NPs) of 300±50 nm size by ionic cross-linking method. The prepared Ami-O-CMC NPs had an encapsulation efficiency of 55.39%. Haemolysis assay and cytotoxicity studies proved the hemocompatibility and cytocompatibility of the prepared NPs. The sustained release of Ami from the NPs is expected to prolong its immunogenicity and in turn lead to development of better protective immunity against Staphylococcus aureus infections. Copyright © 2013 Elsevier B.V. All rights reserved.

Interaction of nanoparticles with proteins: relation to bio-reactivity of the nanoparticle.

PubMed

Saptarshi, Shruti R; Duschl, Albert; Lopata, Andreas L

2013-07-19

Interaction of nanoparticles with proteins is the basis of nanoparticle bio-reactivity. This interaction gives rise to the formation of a dynamic nanoparticle-protein corona. The protein corona may influence cellular uptake, inflammation, accumulation, degradation and clearance of the nanoparticles. Furthermore, the nanoparticle surface can induce conformational changes in adsorbed protein molecules which may affect the overall bio-reactivity of the nanoparticle. In depth understanding of such interactions can be directed towards generating bio-compatible nanomaterials with controlled surface characteristics in a biological environment. The main aim of this review is to summarise current knowledge on factors that influence nanoparticle-protein interactions and their implications on cellular uptake.

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and their Influence on Activity and Selectivity

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

Somorjai, Gabor A.; Park, Jeong Y.

2008-02-13

Recent breakthroughs in synthesis in nanosciences have achieved control of size and shapes of nanoparticles that are relevant for catalyst design. In this article, we review the advance of synthesis of nanoparticles, fabrication of two and three dimensional model catalyst system, characterization, and studies of activity and selectivity. The ability to synthesize monodispersed platinum and rhodium nanoparticles in the 1-10 nm range permitted us to study the influence of composition, structure, and dynamic properties of monodispersed metal nanoparticle on chemical reactivity and selectivity. We review the importance of size and shape of nanoparticles to determine the reaction selectivity in multi-pathmore » reactions. The influence of metal-support interaction has been studied by probing the hot electron flows through the metal-oxide interface in catalytic nanodiodes. Novel designs of nanoparticle catalytic systems are discussed.« less

Aqueous-organic phase-transfer of highly stable gold, silver, and platinum nanoparticles and new route for fabrication of gold nanofilms at the oil/water interface and on solid supports.

PubMed

Feng, Xingli; Ma, Houyi; Huang, Shaoxin; Pan, Wei; Zhang, Xiaokai; Tian, Fang; Gao, Caixia; Cheng, Yingwen; Luo, Jingli

2006-06-29

A simple but effective aqueous-organic phase-transfer method for gold, silver, and platinum nanoparticles was developed on the basis of the decrease of the PVP's solubility in water with the temperature increase. The present method is superior in the transfer efficiency of highly stable nanoparticles to the common phase-transfer methods. The gold, silver, and platinum nanoparticles transferred to the 1-butanol phase dispersed well, especially silver and platinum particles almost kept the previous particle size. Electrochemical synthesis of gold nanoparticles in an oil-water system was achieved by controlling the reaction temperature at 80 degrees C, which provides great conveniences for collecting metal particles at the oil/water interface and especially for fabricating dense metal nanoparticle films. A technique to fabricate gold nanofilms on solid supports was also established. The shapes and sizes of gold nanoparticles as the building blocks may be controllable through changing reaction conditions.

Convection-enhanced delivery and in vivo imaging of polymeric nanoparticles for the treatment of malignant glioma.

PubMed

Bernal, Giovanna M; LaRiviere, Michael J; Mansour, Nassir; Pytel, Peter; Cahill, Kirk E; Voce, David J; Kang, Shijun; Spretz, Ruben; Welp, Ulrich; Noriega, Sandra E; Nunez, Luis; Larsen, Gustavo F; Weichselbaum, Ralph R; Yamini, Bakhtiar

2014-01-01

A major obstacle to the management of malignant glioma is the inability to effectively deliver therapeutic agent to the tumor. In this study, we describe a polymeric nanoparticle vector that not only delivers viable therapeutic, but can also be tracked in vivo using MRI. Nanoparticles, produced by a non-emulsion technique, were fabricated to carry iron oxide within the shell and the chemotherapeutic agent, temozolomide (TMZ), as the payload. Nanoparticle properties were characterized and subsequently their endocytosis-mediated uptake by glioma cells was demonstrated. Convection-enhanced delivery (CED) can disperse nanoparticles through the rodent brain and their distribution is accurately visualized by MRI. Infusion of nanoparticles does not result in observable animal toxicity relative to control. CED of TMZ-bearing nanoparticles prolongs the survival of animals with intracranial xenografts compared to control. In conclusion, the described nanoparticle vector represents a unique multifunctional platform that can be used for image-guided treatment of malignant glioma. GBM remains one of the most notoriously treatment-unresponsive cancer types. In this study, a multifunctional nanoparticle-based temozolomide delivery system was demonstrated to possess enhanced treatment efficacy in a rodent xenograft GBM model, with the added benefit of MRI-based tracking via the incorporation of iron oxide as a T2* contrast material in the nanoparticles. © 2014.

Controlled synthesis of germanium nanoparticles by nonthermal plasmas

NASA Astrophysics Data System (ADS)

Ahadi, Amir Mohammad; Hunter, Katharine I.; Kramer, Nicolaas J.; Strunskus, Thomas; Kersten, Holger; Faupel, Franz; Kortshagen, Uwe R.

2016-02-01

The size, composition, and crystallinity of plasma produced nanoparticles are crucial factors for their physical and chemical properties. Here, we investigate the role of the process gas composition, particularly the hydrogen (H2) flow rate, on germanium (Ge) nanoparticles synthesized from a chlorinated precursor by nonthermal plasma. We demonstrate that the gas composition can significantly change the nanoparticle size and also adjust the surface chemistry by altering the dominant reaction mechanisms. A red shift of the Ge-Clx infrared absorptions with increasing H2 flow indicates a weakening of the Ge-Clx bonds at high H2 content. Furthermore, by changing the gas composition, the nanoparticles microstructure can be controlled from mostly amorphous at high hydrogen flow to diamond cubic crystalline at low hydrogen flow.

Visualization of MMP-2 Activity Using Dual-Probe Nanoparticles to Detect Potential Metastatic Cancer Cells

PubMed Central

Kim, Sung Hoon; Lee, Hyun; Kim, Bohee; Kim, Yoon Suk; Key, Jaehong

2018-01-01

Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes capable of degrading extracellular matrix components. Previous studies have shown that the upregulation of MMP-2 is closely related to metastatic cancers. While Western blotting, zymography, and Enzyme-Linked Immunosorbent Assays (ELISA) can be used to measure the amount of MMP-2 activity, it is not possible to visualize the dynamic MMP-2 activities of cancer cells using these techniques. In this study, MMP-2-activated poly(lactic-co-glycolic acid) with polyethylenimine (MMP-2-PLGA-PEI) nanoparticles were developed to visualize time-dependent MMP-2 activities. The MMP-2-PLGA-PEI nanoparticles contain MMP-2-activated probes that were detectable via fluorescence microscopy only in the presence of MMP-2 activity, while the Rhodamine-based probes in the nanoparticles were used to continuously visualize the location of the nanoparticles. This approach allowed us to visualize MMP-2 activities in cancer cells and their microenvironment. Our results showed that the MMP-2-PLGA-PEI nanoparticles were able to distinguish between MMP-2-positive (HaCat) and MMP-2-negative (MCF-7) cells. While the MMP-2-PLGA-PEI nanoparticles gave fluorescent signals recovered by active recombinant MMP-2, there was no signal recovery in the presence of an MMP-2 inhibitor. In conclusion, MMP-2-PLGA-PEI nanoparticles are an effective tool to visualize dynamic MMP-2 activities of potential metastatic cancer cells. PMID:29466303

Biosynthesis of AgNPs using Carica Papaya peel extract and evaluation of its antioxidant and antimicrobial activities.

PubMed

Kokila, T; Ramesh, P S; Geetha, D

2016-12-01

Waste fruit peel mediated synthesis of silver nanoparticles (AgNPs) is a green chemistry approach that links nanotechnology and biotechnology. Using biological medium such as peel extract for the biosynthesis of nanoparticles is an ecofriendly and emerging scientific trend. With this back drop the present study focused on the biosynthesis of AgNPs using Carica Papaya peel extract (CPPE) and evaluation of its antimicrobial potentials of the nanoparticles against different human pathogens and to investigate the free radical scavenging activity. Water soluble antioxidant constituents present in Carica Papaya peel extract were mainly responsible for the reduction of silver ions to nanosized Ag particles. UV-vis spectral analysis shows surface plasmon resonance band at 430nm. The presence of active proteins and phenolic groups present in the biomass before and after reduction was identified by Fourier transform infrared spectroscopy. X-ray diffraction study shows the average size of the silver nanoparticles is in the range of 28nm, as well as revealed their face centered cubic structure. Atomic force microscope image gives the 3D topological characteristic of silver nanoparticles and the particle size ranges from 10 to 30nm. The average particle size distribution of silver nanoparticles is 161nm (Dynamic light scattering) and the corresponding average zeta potential value is -20.5mV, suggesting higher stability of silver nanoparticles. Biologically synthesized nanoparticles efficiently inhibited pathogenic organisms both gram-positive and gram-negative bacteria. The biosynthesized nanoparticles might serve as a potent antioxidant as revealed by DPPH and ABT S+ assay. Copyright © 2016 Elsevier Inc. All rights reserved.

Charge transport in nanoscale "all-inorganic" networks of semiconductor nanorods linked by metal domains.

PubMed

Lavieville, Romain; Zhang, Yang; Casu, Alberto; Genovese, Alessandro; Manna, Liberato; Di Fabrizio, Enzo; Krahne, Roman

2012-04-24

Charge transport across metal-semiconductor interfaces at the nanoscale is a crucial issue in nanoelectronics. Chains of semiconductor nanorods linked by Au particles represent an ideal model system in this respect, because the metal-semiconductor interface is an intrinsic feature of the nanosystem and does not manifest solely as the contact to the macroscopic external electrodes. Here we investigate charge transport mechanisms in all-inorganic hybrid metal-semiconductor networks fabricated via self-assembly in solution, in which CdSe nanorods were linked to each other by Au nanoparticles. Thermal annealing of our devices changed the morphology of the networks and resulted in the removal of small Au domains that were present on the lateral nanorod facets, and in ripening of the Au nanoparticles in the nanorod junctions with more homogeneous metal-semiconductor interfaces. In such thermally annealed devices the voltage dependence of the current at room temperature can be well described by a Schottky barrier lowering at a metal semiconductor contact under reverse bias, if the spherical shape of the gold nanoparticles is considered. In this case the natural logarithm of the current does not follow the square-root dependence of the voltage as in the bulk, but that of V(2/3). From our fitting with this model we extract the effective permittivity that agrees well with theoretical predictions for the permittivity near the surface of CdSe nanorods. Furthermore, the annealing improved the network conductance at cryogenic temperatures, which could be related to the reduction of the number of trap states.

Multilayered Magnetic Nanoparticles Fabricated by Nanoimprint Lithography for Magnetomechanical Treatment of Cancer

NASA Astrophysics Data System (ADS)

Kwon, Byung Seok

Fe3O4-magetite nanoparticles have received wide interest as prominent agents for various biomedical applications, ranging from target-specific cancer treatment, gene therapy, and Magnetic Particle Imaging (MPI). However, Fe3O4-magnetite nanoparticles, synthesized by chemical methods beyond a certain size, present challenges in controlling size distribution and shape. Similarly, Fe3O 4-magnetite nanoparticles fabricated by conventional top-down lithographic methods present difficulty of controlling defects and lead to agglomeration due to large size. In order to overcome the difficulties associated with the conventional chemical and top-down lithographic methods, it is critical to develop a fabrication method which produces homogeneous nanoparticles in large quantities with the control of size, defects, and structure. Furthermore, the concept of cell death induced by mechanical perturbation has received wide attention as a way to maximize the cancer cell death with minimal side effects. Previous study has proposed the use of permalloy disk-shaped vortex state microparticles, in order to create cancer cell death by mechanical force. However, insufficient biocompatibility, inadequate mechanical force created by vortex switching, and inability to control the particle size have been critical issues to be further researched and proceeded for in vivo application. Hence, we studied physical and magnetic properties of Fe3O 4 as a material in thin film form and proceeded to develop Fe3 O4 based synthetic antiferromagnetic (SAF) thin films. Then, we combined these favorable physical/magnetic properties with nanoimprint lithography to fabricate homogeneously patterned synthetic antiferromagnetic (SAF) nanoparticles (wafer area >1 x 1 cm2) with the control of size, shape and structure. Then we demonstrated the release of these particles in an aqueous environment. The fabrication process combines a tetrafluoroethylene (ETFE) "working stamp", a bi-layer resist lift-off, defect-free nanoimprint and sputtering in order to fabricate synthetic antiferromagnetic (SAF) nanoparticles. SAF nanoparticles are composed of alternating magnetic/non-magnetic multilayers to prevent any agglomeration in spite of the ferromagnetic nature of the particles. This heterostructure gives rise to nearly zero magnetic remanence and coercivity values and also prevents possible oxidation of Fe 3O4. The superparamagnet-like behavior (nearly zero remanence and coercivity) of SAF nanoparticles suggests that the SAF nanoparticles with favorable geometry fabricated by top-down methods have potential for biomedical application. In order to prove the suitability of SAF nanoparticles for biomedical application, we initially controlled the movement of these SAF nanoparticles with A.C magnetic field, and mechanically rotated them in solution. After we have studied field frequency dependence on mechanical rotation, these SAF nanoparticles were implemented in in vitro environment to test the biocompatibility of these SAF nanoparticlesn, and also to confirm the effectiveness of mechanical force created by A.C magnetic field in order to kill cancer cells. This proof of concept successfully eradicated cancer cells with these SAF nanoparticles. We have demonstrated the effective cancer death after 16 minutes of exposure to mechanically rotating SAF nanoparticles under frequency of 1 Hz (>92% cell death). Furthermore, under the same frequency and exposure time, we have shown that up to 1:4 (nanoparticles:cell) concentration, the mechanical perturbation is effective to kill cancer cells (>80% cell death). However, we suggest to further study the biological mechanism of cancer cell death by mechanical perturbation to truly understand this phenomenon.

pH-activated Nanoparticles for Controlled Topical Delivery of Farnesol to Disrupt Oral Biofilm Virulence

PubMed Central

Horev, Benjamin; Klein, Marlise I.; Hwang, Geelsu; Li, Yong; Kim, Dongyeop; Koo, Hyun; Benoit, Danielle S.W.

2015-01-01

Development of effective therapies to control oral biofilms is challenging, as topically introduced agents must avoid rapid clearance from biofilm-tooth interfaces while targeting biofilm microenvironments. Additionally, exopolysaccharide matrix and acidification of biofilm microenvironments are associated with cariogenic (caries-producing) biofilm virulence. Thus, nanoparticle carriers capable of binding to hydroxyapatite (HA), saliva-coated HA (sHA), and exopolysaccharides with enhanced drug-release at acidic pH were developed. Nanoparticles are formed from diblock copolymers composed of 2-(dimethylamino)ethyl methacrylate (DMAEMA), butyl methacrylate (BMA), and 2-propylacrylic acid (PAA) (p(DMAEMA)-b-p(DMAEMA-co-BMA-co-PAA)) that self-assemble into ~21 nm cationic nanoparticles. Nanoparticles exhibit outstanding adsorption affinities (~244 L-mmol−1) to negatively-charged HA, sHA, and exopolysaccharide-coated sHA due to strong electrostatic interactions via multivalent tertiary amines of p(DMAEMA). Owing to hydrophobic cores, Nanoparticles load farnesol, a hydrophobic antibacterial drug, at ~22 wt%. Farnesol release is pH-dependent with t1/2=7 and 15 h for release at pH 4.5 and 7.2, as Nanoparticles undergo core destabilization at acidic pH, characteristic of cariogenic biofilm microenvironments. Importantly, topical applications of farnesol-loaded nanoparticles disrupted Streptococcus mutans biofilms 4-fold more effectively than free farnesol. Mechanical stability of biofilms treated with drug-loaded nanoparticles was compromised, resulting in >2-fold enhancement in biofilm removal under shear stress compared to free farnesol and controls. Farnesol-loaded nanoparticles effectively attenuated biofilm virulence in vivo using a clinically-relevant topical treatment regimen (2×/day) in a rodent dental caries disease model. Treatment with farnesol-loaded nanoparticles reduced both the number and severity of carious lesions, while free-farnesol had no effect. Nanoparticles have great potential to enhance the efficacy of antibiofilm agents through multi-targeted binding and pH-responsive drug release due to microenvironmental triggers. PMID:25661192

Active control of silver nanoparticles spacing using dielectrophoresis for surface-enhanced Raman scattering.

PubMed

Chrimes, Adam F; Khoshmanesh, Khashayar; Stoddart, Paul R; Kayani, Aminuddin A; Mitchell, Arnan; Daima, Hemant; Bansal, Vipul; Kalantar-zadeh, Kourosh

2012-05-01

We demonstrate an active microfluidic platform that integrates dielectrophoresis for the control of silver nanoparticles spacing, as they flow in a liquid channel. By careful control of the nanoparticles spacing, we can effectively increase the surface-enhanced Raman scattering (SERS) signal intensity based on augmenting the number of SERS-active hot-spots, while avoiding irreversible aggregation of the particles. The system is benchmarked using dipicolinate (2,6-pyridinedicarboxylic acid) (DPA), which is a biomarker of Bacillus anthracis. The validity of the results is discussed using several complementing characterization scenarios.

Preparation and characterization of magnetic nanoparticles containing Fe(3)O(4)-dextran-anti-β-human chorionic gonadotropin, a new generation choriocarcinoma-specific gene vector.

PubMed

Jingting, Cai; Huining, Liu; Yi, Zhang

2011-01-01

To evaluate the feasibility of using magnetic iron oxide (Fe(3)O(4))-dextran-anti-β-human chorionic gonadotropin (HCG) nanoparticles as a gene vector for cellular transfections. Fe(3)O(4)-dextran-anti-β-HCG nanoparticles were synthesized by chemical coprecipitation. The configuration, diameter, and iron content of the nanoparticles were detected by transmission electron microscopy (TEM), light scatter, and atomic absorption spectrophotometry. A3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide assay was used to evaluate the cytotoxicity of Fe(3)O(4)-dextran-anti-β-HCG nanoparticles. Enzyme-linked immunosorbent assay and indirect immunofluorescence were used to evaluate immunoreactivity. The efficiency of absorbing DNA and resisting deoxyribonuclease I (DNase I) digestion when bound to Fe(3)O(4)-dextran-anti-β-HCG nanoparticles was examined by agarose gel electrophoresis. The ability of Fe(3)O(4)-dextran-anti-β-HCG nanoparticles to absorb heparanase antisense oligodeoxynucleotides (AS-ODN) nanoparticles in different cell lines was evaluated by flow cytometry. The tissue distribution of heparanase AS-ODN magnetic nanoparticles in choriocarcinoma tumors transplanted in nude mice was detected by atomic absorption spectrophotometry. TEM demonstrated that the shape of nanoparticles is irregular. Light scatter revealed nanoparticles with a mean diameter of 75.5 nm and an iron content of 37.5 μg/mL. No cytotoxicity was observed when the concentration of Fe(3)O(4)-dextran-anti-β-HCG nanoparticles was <37.5 μg/mL. Fe(3)O(4)-dextran nanoparticles have a satisfactory potential to combine with β-HCG antibody. Agarose gel electrophoresis analysis of binding experiments showed that after treatment with sodium periodate, Fe(3)O(4)-dextran-anti-β-HCG nanoparticles have a satisfactory potential to absorb DNA, and the protection experiment showed that nanoparticles can effectively protect DNA from DNase I digestion. Aldehyde Fe(3)O(4)-dextran-anti-β-HCG nanoparticles can transfect reporter genes, and the transfection efficiency of these nanoparticles is greater than that of liposomes (P < 0.05). Fe(3)O(4)-dextran-anti-β-HCG nanoparticles can concentrate in choriocarcinoma cells and in transplanted choriocarcinoma tumors. The results confirm that Fe(3)O(4)-dextran-anti-β-HCG nanoparticles have potential as a secure, effective, and choriocarcinoma-specific targeting gene vector.

Enhanced Intratumoral Delivery of SN38 as a Tocopherol Oxyacetate Prodrug Using Nanoparticles in a Neuroblastoma Xenograft Model.

PubMed

Nguyen, Ferro; Alferiev, Ivan; Guan, Peng; Guerrero, David T; Kolla, Venkatadri; Moorthy, Ganesh S; Chorny, Michael; Brodeur, Garrett M

2018-06-01

Purpose: Currently, <50% of high-risk pediatric solid tumors like neuroblastoma can be cured, and many survivors experience serious or life-threatening toxicities, so more effective, less toxic therapy is needed. One approach is to target drugs to tumors using nanoparticles, which take advantage of the enhanced permeability of tumor vasculature. Experimental Design: SN38, the active metabolite of irinotecan (CPT-11), is a potent therapeutic agent that is readily encapsulated in polymeric nanoparticles. Tocopherol oxyacetate (TOA) is a hydrophobic mitocan that was linked to SN38 to significantly increase hydrophobicity and enhance nanoparticle retention. We treated neuroblastomas with SN38-TOA nanoparticles and compared the efficacy with the parent prodrug CPT-11 using a mouse xenograft model. Results: Nanoparticle treatment induced prolonged event-free survival (EFS) in most mice, compared with CPT-11. This was shown for both SH-SY5Y and IMR-32 neuroblastoma xenografts. Enhanced efficacy was likely due to increased and sustained drug levels of SN38 in the tumor compared with conventional CPT-11 delivery. Interestingly, when recurrent CPT-11-treated tumors were re-treated with SN38-TOA nanoparticles, the tumors transformed from undifferentiated neuroblastomas to maturing ganglioneuroblastomas. Furthermore, these tumors were infiltrated with Schwann cells of mouse origin, which may have contributed to the differentiated histology. Conclusions: Nanoparticle delivery of SN38-TOA produced increased drug delivery and prolonged EFS compared to conventional delivery of CPT-11. Also, lower total dose and drug entrapment in nanoparticles during circulation should decrease toxicity. We propose that nanoparticle-based delivery of a rationally designed prodrug is an attractive approach to enhance chemotherapeutic efficacy in pediatric and adult tumors. Clin Cancer Res; 24(11); 2585-93. ©2018 AACR . ©2018 American Association for Cancer Research.

Chitosan-based nanoparticles for improving immunization against hepatitis B infection.

PubMed

Prego, Cecilia; Paolicelli, Patrizia; Díaz, Belen; Vicente, Sara; Sánchez, Alejandro; González-Fernández, Africa; Alonso, María José

2010-03-19

The design of effective vaccine delivery vehicles is opening up new possibilities for making immunization more equitable, safe and efficient. In this work, we purpose polysaccharidic-based nanoparticles as delivery structures for virus-like particle antigens, using recombinant hepatitis B surface antigen (rHBsAg) as a model. Polysaccharidic-based nanoparticles were prepared using a very mild ionic gelation technique, by cross-linking the polysaccharide chitosan (CS) with a counter ion. The resulting nanoparticles could be easily isolated with a size in the nanometric range (160-200 nm) and positive surface charge (+6 to +10 mV). More importantly, CS-based nanoparticles allowed the efficient association of the antigen (>60%) while maintaining the antigenic epitope intact, as determined by ELISA and Western blot. The entrapped antigen was further released in vitro from the nanoparticles in a sustained manner without compromising its antigenicity. In addition, loaded CS-based nanoparticles were stable, and protected the associated antigen during storage, either as an aqueous suspension under different temperature conditions (+4 degrees C and -20 degrees C), or as a dried form after freeze-drying the nanoparticles. Finally, immunization studies showed the induction of important seroprotection rates after intramuscular administration of the nanoparticles, indicating their adjuvant capacity. In fact, CS-based nanoparticles were able to induce anti-HBsAg IgG levels up to 5500 mIU/ml, values 9-fold the conventional alum-adsorbed vaccine. In conclusion, we report here a polysaccharidic nanocarrier which exhibits a number of in vitro and in vivo features that make it a promising adjuvant for vaccine delivery of subunit antigens. Copyright 2010 Elsevier Ltd. All rights reserved.

Stability, Intracellular Delivery, and Release of siRNA from Chitosan Nanoparticles Using Different Cross-Linkers

PubMed Central

Abdul Ghafoor Raja, Maria; Katas, Haliza; Jing Wen, Thum

2015-01-01

Chitosan (CS) nanoparticles have been extensively studied for siRNA delivery; however, their stability and efficacy are highly dependent on the types of cross-linker used. To address this issue, three common cross-linkers; tripolyphosphate (TPP), dextran sulphate (DS) and poly-D-glutamic acid (PGA) were used to prepare siRNA loaded CS-TPP/DS/PGA nanoparticles by ionic gelation method. The resulting nanoparticles were compared with regard to their physicochemical properties including particle size, zeta potential, morphology, binding and encapsulation efficiencies. Among all the formulations prepared with different cross linkers, CS-TPP-siRNA had the smallest particle size (ranged from 127 ± 9.7 to 455 ± 12.9 nm) with zeta potential ranged from +25.1 ± 1.5 to +39.4 ± 0.5 mV, and high entrapment (>95%) and binding efficiencies. Similarly, CS-TPP nanoparticles showed better siRNA protection during storage at 4˚C and as determined by serum protection assay. TEM micrographs revealed the assorted morphology of CS-TPP-siRNA nanoparticles in contrast to irregular morphology displayed by CS-DS-siRNA and CS-PGA-siRNA nanoparticles. All siRNA loaded CS-TPP/DS/PGA nanoparticles showed initial burst release followed by sustained release of siRNA. Moreover, all the formulations showed low and concentration-dependent cytotoxicity with human colorectal cancer cells (DLD-1), in vitro. The cellular uptake studies with CS-TPP-siRNA nanoparticles showed successful delivery of siRNA within cytoplasm of DLD-1 cells. The results demonstrate that ionically cross-linked CS-TPP nanoparticles are biocompatible non-viral gene delivery system and generate a solid ground for further optimization studies, for example with regard to steric stabilization and targeting. PMID:26068222

Optimization and characterization of high pressure homogenization produced chemically modified starch nanoparticles.

PubMed

Ding, Yongbo; Kan, Jianquan

2017-12-01

Chemically modified starch (RS4) nanoparticles were synthesized through homogenization and water-in-oil mini-emulsion cross-linking. Homogenization was optimized with regard to z-average diameter by using a three-factor-three-level Box-Behnken design. Homogenization pressure (X 1 ), oil/water ratio (X 2 ), and surfactant (X 3 ) were selected as independent variables, whereas z-average diameter was considered as a dependent variable. The following optimum preparation conditions were obtained to achieve the minimum average size of these nanoparticles: 50 MPa homogenization pressure, 10:1 oil/water ratio, and 2 g surfactant amount, when the predicted z-average diameter was 303.6 nm. The physicochemical properties of these nanoparticles were also determined. Dynamic light scattering experiments revealed that RS4 nanoparticles measuring a PdI of 0.380 and an average size of approximately 300 nm, which was very close to the predicted z-average diameter (303.6 nm). The absolute value of zeta potential of RS4 nanoparticles (39.7 mV) was higher than RS4 (32.4 mV), with strengthened swelling power. X-ray diffraction results revealed that homogenization induced a disruption in crystalline structure of RS4 nanoparticles led to amorphous or low-crystallinity. Results of stability analysis showed that RS4 nanosuspensions (particle size) had good stability at 30 °C over 24 h.

Silica sol as grouting material: a physio-chemical analysis.

PubMed

Sögaard, Christian; Funehag, Johan; Abbas, Zareen

2018-01-01

At present there is a pressing need to find an environmentally friendly grouting material for the construction of tunnels. Silica nanoparticles hold great potential of replacing the organic molecule based grouting materials currently used for this purpose. Chemically, silica nanoparticles are similar to natural silicates which are essential components of rocks and soil. Moreover, suspensions of silica nanoparticles of different sizes and desired reactivity are commercially available. However, the use of silica nanoparticles as grouting material is at an early stage of its technological development. There are some critical parameters such as long term stability and functionality of grouted silica that need to be investigated in detail before silica nanoparticles can be considered as a reliable grouting material. In this review article we present the state of the art regarding the chemical properties of silica nanoparticles commercially available, as well as experience gained from the use of silica as grouting material. We give a detailed description of the mechanisms underlying the gelling of silica by different salt solutions such as NaCl and KCl and how factors such as particle size, pH, and temperature affect the gelling and gel strength development. Our focus in this review is on linking the chemical properties of silica nanoparticles to the mechanical properties to better understand their functionality and stability as grouting material. Along the way we point out areas which need further research.

Metal nanoparticles in diesel exhaust derived by in-cylinder melting of detached engine fragments

NASA Astrophysics Data System (ADS)

Liati, Anthi; Pandurangi, Sushant Sunil; Boulouchos, Konstantinos; Schreiber, Daniel; Arroyo Rojas Dasilva, Yadira

2015-01-01

A wide range of environmental and health effects are linked to combustion-generated pollutants related to traffic. Nanoparticles, in particular, are a major concern for humans since they can be inhaled and have potentially toxic effects. The variability and sources of combustion-related nanoparticle pollutants remain inadequately investigated. Here we report the presence of ca. 5-100 nm large Fe3O4 nanoparticles, in form of agglomerates, in diesel exhaust. The mode of occurrence of these nanoparticles, in combination with their chemical composition matching that of steel indicate that they derive by melting of engine fragments in the combustion chamber and subsequent crystallization during cooling. To evaluate this hypothesis, we applied CFD simulations of material transport in the cylinder of a diesel engine, assuming detachment of steel fragments from various sites of the cylinder. The CFD results show that fragments ≤20 μm in size dislodged from the piston surface or from the fuel nozzle interior can be indeed transported to such hot areas of the combustion chamber where they can melt. The simulation results concur with the experimental observations and point out that metal nanoparticle formation by in-cylinder melting of engine fragments can occur in diesel engines. The present study proposes a hitherto neglected formation mechanism of metal nanoparticle emissions from internal combustion engines raising possible environmental and health concerns, especially in urban areas.

Labeling TiO2 nanoparticles with dyes for optical fluorescence microscopy and determination of TiO2-DNA nanoconjugate stability.

PubMed

Thurn, Kenneth T; Paunesku, Tatjana; Wu, Aiguo; Brown, Eric M B; Lai, Barry; Vogt, Stefan; Maser, Jörg; Aslam, Mohammed; Dravid, Vinayak; Bergan, Raymond; Woloschak, Gayle E

2009-06-01

Visualization of nanoparticles without intrinsic optical fluorescence properties is a significant problem when performing intracellular studies. Such is the case with titanium dioxide (TiO2) nanoparticles. These nanoparticles, when electronically linked to single-stranded DNA oligonucleotides, have been proposed to be used both as gene knockout devices and as possible tumor imaging agents. By interacting with complementary target sequences in living cells, these photoinducible TiO2-DNA nanoconjugates have the potential to cleave intracellular genomic DNA in a sequence specific and inducible manner. The nanoconjugates also become detectable by magnetic resonance imaging with the addition of gadolinium Gd(III) contrast agents. Herein two approaches for labeling TiO2 nanoparticles and TiO2-DNA nanoconjugates with optically fluorescent agents are described. This permits direct quantification of fluorescently labeled TiO2 nanoparticle uptake in a large population of living cells (>10(4) cells). X-ray fluorescence microscopy (XFM) is combined with fluorescent microscopy to determine the relative intracellular stability of the nanoconjugates and used to quantify intracellular nanoparticles. Imaging the DNA component of the TiO2-DNA nanoconjugate by fluorescent confocal microscopy within the same cell shows an overlap with the titanium signal as mapped by XFM. This strongly implies the intracellular integrity of the TiO2-DNA nanoconjugates in malignant cells.

Enhanced stability of L-asparaginase by its bioconjugation to poly(styrene-co-maleic acid) and Ecoflex nanoparticles.

PubMed

Varshosaz, Jaleh; Anvari, Negin

2018-06-01

Acute lymphoblastic leukemia (ALL) is the white blood cell cancer in children. L-asparaginase (L-ASNase) is one of the first drugs used in ALL treatment. Anti-tumor activity of L-ASNase is not specific and indicates limited stability in different biological environments, in addition to its quick clearance from blood. The purpose of the present study was to achieve a new L-ASNase polymer bioconjugate to improve pharmacokinetic, increase half-life and stability of the enzyme. The conjugations were achieved by the cross-linking agent of 1-ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDC) which activates the carboxylic acid groups of polymeric nanoparticles to create amide bond. EDC conjugated the L-ASNase to two biodegradable polymers including; Ecoflex ® and poly (styrene-co-maleic acid) (PSMA) nanoparticles. To achieve optimal L-ASNase nanoparticles the amounts of each polymer and the crosslinker were optimized and the nanoparticles were characterized according to their particle size, zeta potential and percent of conjugation of the enzyme. The results showed that conjugated enzyme had more stability against pH changes and proteolysis. It had lower Km value (indicating more affinity to the substrate) and greater half-life in plasma and phosphate buffered saline, in comparison to native enzyme. Generally, the conjugated enzyme to PSMA nanoparticles showed greater results than Ecoflex ® nanoparticles.

Fluorescent silica nanoparticles containing covalently bound dyes for reporter, marker, and sensor applications

NASA Astrophysics Data System (ADS)

Patonay, Gabor; Henary, Maged; Chapman, Gala; Emer, Kyle; Crow, Sidney

2016-03-01

Silica nanoparticles have proven to be useful in many bioanalytical and medical applications and have been used in numerous applications during the last decade. Combining the properties of silica nanoparticles and fluorescent dyes that may be used as chemical probes or labels can be relatively easy by simply soaking porous silica nanoparticles in a solution of the dye of interest. Under proper conditions the entrapped dye can stay inside the silica nanoparticle for several hours resulting in a useful probe. In spite of the relative durability of these probes, leaching can still occur. A much better approach is to synthesize silica nanoparticles that have the fluorescent dye covalently attached to the backbone structure of the silica nanoparticle. This can be achieved by using appropriately modified tetraethyl orthosilicate (TEOS) analogues during the silica nanoparticle synthesis. The molar ratio of TEOS and modified TEOS will determine the fluorescent dye load in the silica nanoparticle. Dependent on the chemical stability of the reporting dye either reverse micellar (RM) or Stöber method can be used for silica nanoparticle synthesis. If dye stability allows RM procedure is preferred as it results in a much easier control of the silica nanoparticle reaction itself. Also controlling the size and uniformity of the silica nanoparticles are much easier using RM method. Dependent on the functional groups present in the reporting dye used in preparation of the modified TEOS, the silica nanoparticles can be utilized in many applications such as pH sensor, metal ion sensors, labels, etc. In addition surface activated silica nanoparticles with reactive moieties are also excellent reporters or they can be used as bright fluorescent labels. Many different fluorescent dyes can be used to synthesize silica nanoparticles including visible and NIR dyes. Several bioanalytical applications are discussed including studying amoeba phagocytosis.

Macrophage Targeted Nanoparticles for Antiretroviral (ARV) Delivery

PubMed Central

Kutscher, Hilliard L.; Makita-Chingombe, Faithful; DiTursi, Sara; Singh, Ajay; Dube, Admire; Maponga, Charles C.; Morse, Gene D.; Reynolds, Jessica L.

2017-01-01

Objective To reduce the amount of the antiretroviral (ARV) nevirapine necessary to achieve therapeutic concentrations using macrophage targeted nanoparticles. Methods Core-shell nanoparticles were prepared from FDA approved, biodegradable and biocompatible polymers, with poly(lactic-co-glycolic) acid (PLGA) as the core and chitosan (CS) as the shell using a water/oil/water method. Nevirapine was encapsulated in the core of the nanoparticles. β-glucan (GLU) was adsorbed to the surface of the nanoparticle. Macrophage uptake and intracellular nevirapine concentrations were determined by fluorescence imaging and ultra-performance liquid chromatography/mass spectroscopy (UPLC-MS). Optical imaging was employed to characterize the biodistribution of nanoparticles following intravenous injection in CD-1 mice. Results We synthesized spherical shaped 190 nm GLU-CS-PLGA nanoparticles that provide controlled release of nevirapine. In THP-1 macrophage the uptake of PLGA and CS- PLGA nanoparticles was less compared to targeted GLU-CS-PLGA nanoparticles. THP-1 macrophage were dosed with free nevirapine (10 μg/well) and GLU-CS- PLGA nanoparticles containing 1/10 the concentration of free nevirapine (1 μg nevirapine/well). The intracellular concentration of nevirapine was the same for both nanoparticles and free nevirapine at 2 and 24 hrs. No significant change in THP-1 macrophage viability was observed in the presence of nanoparticles relative to the control. Ex vivo imaging demonstrates that nanoparticles are predominantly found in the liver and kidney and at 24 hr there is still a large amount of nanoparticles in the body. Conclusion These data demonstrate that the total dose of nevirapine delivered by GLU-CS-PLGA nanoparticles can be greatly reduced, to limit side effects, while still providing maximal ARV activity in a known cellular reservoir. PMID:29492319

Controlled supramolecular assembly of micelle-like gold nanoparticles in PS-b-P2VP diblock copolymers via hydrogen bonding.

PubMed

Jang, Se Gyu; Kramer, Edward J; Hawker, Craig J

2011-10-26

We report a facile strategy to synthesize amphiphilic gold (Au) nanoparticles functionalized with a multilayer, micelle-like structure consisting of a Au core, an inner hydroxylated polyisoprene (PIOH) layer, and an outer polystyrene shell (PS). Careful control of enthalpic interactions via a systematic variation of structural parameters, such as number of hydroxyl groups per ligand (N(OH)) and styrene repeating units (N(PS)) as well as areal chain density of ligands on the Au-core surface (Σ), enables precise control of the spatial distribution of these nanoparticles. This control was demonstrated in a lamellae-forming poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) diblock copolymer matrix, where the favorable hydrogen-bonding interaction between hydroxyl groups in the PIOH inner shell and P2VP chains in the PS-b-P2VP diblock copolymer matrix, driving the nanoparticles to be segregated in P2VP domains, could be counter balanced by the enthalphic penalty of mixing of the PS outer brush with the P2VP domains. By varying N(OH), N(PS), and Σ, the nanoparticles could be positioned in the PS or P2VP domains or at the PS/P2VP interface. In addition, the effect of additives interfering with the hydrogen-bond formation between hydroxyl groups on Au nanoparticles and P2VP chains in a diblock copolymer matrix was investigated, and an interesting pea-pod-like segregation of Au nanoparticles in PS domains was observed.

Comparative Study of Rhodamine B degradation by Tio2 nanoparticles synthesized from titanium sec butoxide and its chloroacetato derivatves.

PubMed

Ambreen, S; Pandey, N D; Pandey, A

2017-07-31

TiO2 has been well recognized as a proficient photocatalyst. TiO2 nanoparticles have been synthesized from titanium sec butoxide (1) and its monochloroacetate derived compounds. The modifications of Ti(OsBu)4 with monochloroacetic acid in 1:1 and 1:2 molar ratios afforded Ti(OsBu)3(OOCCH2Cl) (2) and Ti(OsBu)2(OOCCH2Cl)2 (3), respectively. The use of monochloroacetic acid as a modifier allows the control of both the degree of condensation and oligomerization of the precursor. The cross linking of the gel and connectivity of the molecular building blocks are lowered in these heteroleptic alkoxides which results in the formation of gels instead of crystalline precipitate. This modification of the precursors leads to the generation of new building blocks which significantly affect the properties of the resulting TiO2. TiO2 powders were prepared via sol-gel method from these precursors and calcined at 400°C and 600°C for 4 h. Phase and morphology of the prepared metal oxide nanoparticles were studied. XRD patterns showed TiO2 in anatase phase. After coating with the surfactant trioctyl phosphinoxide (TOPO), TiO2 particles were dispersed in chloroform to study the particle size and distribution. The optical properties were studied by UV-VIS drs. The photocatalytic activity was studied over the degradation of Rhodamine B under UV radiation.

Supra-Nanoparticle Functional Assemblies through Programmable Stacking

DOE PAGES

Tian, Cheng; Cordeiro, Marco Aurelio L.; Lhermitte, Julien; ...

2017-05-25

The quest for the by-design assembly of material and devices from nanoscale inorganic components is well recognized. Conventional self-assembly is often limited in its ability to control material morphology and structure simultaneously. We report a general method of assembling nanoparticles in a linear “pillar” morphology with regulated internal configurations. Our approach is inspired by supramolecular systems, where intermolecular stacking guides the assembly process to form diverse linear morphologies. Programmable stacking interactions were realized through incorporation of DNA coded recognition between the designed planar nanoparticle clusters. This resulted in the formation of multilayered pillar architectures with a well-defined internal nanoparticle organization.more » Furthermore, by controlling the number, position, size, and composition of the nanoparticles in each layer, a broad range of nanoparticle pillars were assembled and characterized in detail. In addition, we demonstrated the utility of this stacking assembly strategy for investigating plasmonic and electrical transport properties.« less

Supra-Nanoparticle Functional Assemblies through Programmable Stacking

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

Tian, Cheng; Cordeiro, Marco Aurelio L.; Lhermitte, Julien

The quest for the by-design assembly of material and devices from nanoscale inorganic components is well recognized. Conventional self-assembly is often limited in its ability to control material morphology and structure simultaneously. We report a general method of assembling nanoparticles in a linear “pillar” morphology with regulated internal configurations. Our approach is inspired by supramolecular systems, where intermolecular stacking guides the assembly process to form diverse linear morphologies. Programmable stacking interactions were realized through incorporation of DNA coded recognition between the designed planar nanoparticle clusters. This resulted in the formation of multilayered pillar architectures with a well-defined internal nanoparticle organization.more » Furthermore, by controlling the number, position, size, and composition of the nanoparticles in each layer, a broad range of nanoparticle pillars were assembled and characterized in detail. In addition, we demonstrated the utility of this stacking assembly strategy for investigating plasmonic and electrical transport properties.« less

Supra-Nanoparticle Functional Assemblies through Programmable Stacking.

PubMed

Tian, Cheng; Cordeiro, Marco Aurelio L; Lhermitte, Julien; Xin, Huolin L; Shani, Lior; Liu, Mingzhao; Ma, Chunli; Yeshurun, Yosef; DiMarzio, Donald; Gang, Oleg

2017-07-25

The quest for the by-design assembly of material and devices from nanoscale inorganic components is well recognized. Conventional self-assembly is often limited in its ability to control material morphology and structure simultaneously. Here, we report a general method of assembling nanoparticles in a linear "pillar" morphology with regulated internal configurations. Our approach is inspired by supramolecular systems, where intermolecular stacking guides the assembly process to form diverse linear morphologies. Programmable stacking interactions were realized through incorporation of DNA coded recognition between the designed planar nanoparticle clusters. This resulted in the formation of multilayered pillar architectures with a well-defined internal nanoparticle organization. By controlling the number, position, size, and composition of the nanoparticles in each layer, a broad range of nanoparticle pillars were assembled and characterized in detail. In addition, we demonstrated the utility of this stacking assembly strategy for investigating plasmonic and electrical transport properties.

Synthesis of silver nanoparticles by coastal plant Prosopis chilensis (L.) and their efficacy in controlling vibriosis in shrimp Penaeus monodon

NASA Astrophysics Data System (ADS)

Kandasamy, Kathiresan; Alikunhi, Nabeel M.; Manickaswami, Gayathridevi; Nabikhan, Asmathunisha; Ayyavu, Gopalakrishnan

2013-02-01

The present work investigated the effect of leaf extract from coastal plant Prosopis chilensis on synthesis of silver nanoparticles using AgNO3 as a substrate and to find their antibacterial potential on pathogenic Vibrio species in the shrimp, Penaeus monodon. The leaf extract could be able to produce silver nanoparticles, as evident by gradual change in colour of the reaction mixture consisted of the extract and 1 mM AgNO3 to dark brown. The silver nanoparticles exhibited 2 θ values corresponding to the presence of silver nanocrystal, as evident by X-ray diffraction spectrum. The peaks corresponding to flavanones and terpenoids were found to be stabilizing agents of the nanoparticles, as revealed by Fourier transform infrared spectroscopy. The size of silver nanoparticles ranged from 5 to 25 nm with an average of 11.3 ± 2.1 nm and was mostly of spherical in shape, as confirmed by transmission electron microscopy. The silver nanoparticles were found to inhibit Vibrio pathogens viz., Vibrio cholerae, V. harveyi, and V. parahaemolyticus and this antibacterial effect was better than that of leaf extract, as proved by disc diffusion assay. The nanoparticles were then tested in the shrimp Penaeus monodon challenged with the four species of Vibrio pathogens for 30 days. The shrimps fed with silver nanoparticles exhibited higher survival, associated with immunomodulation in terms of higher haemocyte counts, phenoloxidase and antibacterial activities of haemolymph of P. monodon which is on par with that of control. Thus, the present study proved the possibility of using silver nanoparticles produced by coastal Prosopis chilensis as antibacterial agent in controlling vibriosis.

Metallic nanoparticle deposition techniques for enhanced organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Cacha, Brian Joseph Gonda

Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C60/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (Voc) by 160% and short circuit current (Jsc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

Long-circulating Janus nanoparticles made by electrohydrodynamic co-jetting for systemic drug delivery applications.

PubMed

Rahmani, Sahar; Villa, Carlos H; Dishman, Acacia F; Grabowski, Marika E; Pan, Daniel C; Durmaz, Hakan; Misra, Asish C; Colón-Meléndez, Laura; Solomon, Michael J; Muzykantov, Vladimir R; Lahann, Joerg

2015-01-01

Nanoparticles with controlled physical properties have been widely used for controlled release applications. In addition to shape, the anisotropic nature of the particles can be an important design criterion to ensure selective surface modification or independent release of combinations of drugs. Electrohydrodynamic (EHD) co-jetting is used for the fabrication of uniform anisotropic nanoparticles with individual compartments and initial physicochemical and biological characterization is reported. EHD co-jetting is used to create nanoparticles, which are characterized at each stage with scanning electron microscopy (SEM), structured illumination microscopy (SIM), dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Surface immobilization techniques are used to incorporate polyethylene glycol (PEG) and I(125) radiolabels into the nanoparticles. Particles are injected in mice and the particle distribution after 1, 4 and 24 hours is assessed. Nanoparticles with an average diameter of 105.7 nm are prepared by EHD co-jetting. The particles contain functional chemical groups for further surface modification and radiolabeling. The density of PEG molecules attached to the surface of nanoparticles is determined to range between 0.02 and 6.04 ligands per square nanometer. A significant fraction of the nanoparticles (1.2% injected dose per mass of organ) circulates in the blood after 24 h. EHD co-jetting is a versatile method for the fabrication of nanoparticles for drug delivery. Circulation of the nanoparticles for 24 h is a pre-requisite for subsequent studies to explore defined targeting of the nanoparticles to a specific anatomic site.

Targeting Endothelial Cells with Multifunctional GaN/Fe Nanoparticles

NASA Astrophysics Data System (ADS)

Braniste, Tudor; Tiginyanu, Ion; Horvath, Tibor; Raevschi, Simion; Andrée, Birgit; Cebotari, Serghei; Boyle, Erin C.; Haverich, Axel; Hilfiker, Andres

2017-08-01

In this paper, we report on the interaction of multifunctional nanoparticles with living endothelial cells. The nanoparticles were synthesized using direct growth of gallium nitride on zinc oxide nanoparticles alloyed with iron oxide followed by core decomposition in hydrogen flow at high temperature. Using transmission electron microscopy, we demonstrate that porcine aortic endothelial cells take up GaN-based nanoparticles suspended in the growth medium. The nanoparticles are deposited in vesicles and the endothelial cells show no sign of cellular damage. Intracellular inert nanoparticles are used as guiding elements for controlled transportation or designed spatial distribution of cells in external magnetic fields.

Sculpting and fusing biomimetic vesicle networks using optical tweezers.

PubMed

Bolognesi, Guido; Friddin, Mark S; Salehi-Reyhani, Ali; Barlow, Nathan E; Brooks, Nicholas J; Ces, Oscar; Elani, Yuval

2018-05-14

Constructing higher-order vesicle assemblies has discipline-spanning potential from responsive soft-matter materials to artificial cell networks in synthetic biology. This potential is ultimately derived from the ability to compartmentalise and order chemical species in space. To unlock such applications, spatial organisation of vesicles in relation to one another must be controlled, and techniques to deliver cargo to compartments developed. Herein, we use optical tweezers to assemble, reconfigure and dismantle networks of cell-sized vesicles that, in different experimental scenarios, we engineer to exhibit several interesting properties. Vesicles are connected through double-bilayer junctions formed via electrostatically controlled adhesion. Chemically distinct vesicles are linked across length scales, from several nanometres to hundreds of micrometres, by axon-like tethers. In the former regime, patterning membranes with proteins and nanoparticles facilitates material exchange between compartments and enables laser-triggered vesicle merging. This allows us to mix and dilute content, and to initiate protein expression by delivering biomolecular reaction components.

Magnetorheological technology for fabricating tunable solid electrolyte with enhanced conductivity and mechanical property

NASA Astrophysics Data System (ADS)

Peng, Gangrou; Ge, Yu; Ding, Jie; Wang, Caiyun; Wallace, Gordon G.; Li, Weihua

2018-03-01

Ionogels are a new class of hybrid materials where ionic liquids are immobilized by macromolecular support. The excessive amount of crosslinking polymer enhances the mechanical strength but compromises the conductivity. Here, we report an elastomeric magnetorheological (MR) ionogel with an enhanced conductivity and mechanical strength as well. Following the application of magnetic nanoparticles into an ionic liquid containing minimum cross-linking agent, the formation, thus physical properties, of MR ionogels are co-controlled by simultaneously applied UV light and external magnetic field. The application of MR ionogels as solid electrolytes in supercapacitors is also demonstrated to study electrochemical performance. This work opens a new avenue to synthesize robust ionogels with the desired conductivity and controllable mechanical properties for soft flexible electronic devices. Besides, as a new class of conductive MR elastomers, the proposed MR ionogel also possesses the potential for engineering applications, such as sensors and actuators.

Interfacial functionalization and engineering of nanoparticles

NASA Astrophysics Data System (ADS)

Song, Yang

The intense research interest in nanoscience and nanotechnology is largely fueled by the unique properties of nanoscale materials. In this dissertation, the research efforts are focused on surface functionalization and interfacial engineering of functional nanoparticles in the preparation of patchy nanoparticles (e.g., Janus nanoparticles and Neapolitan nanoparticles) such that the nanoparticle structures and properties may be manipulated to an unprecedented level of sophistication. Experimentally, Janus nanoparticles were prepared by an interfacial engineering method where one hemisphere of the originally hydrophobic nanoparticles was replaced with hydrophilic ligands at the air|liquid or solid|liquid interface. The amphiphilic surface characters of the Janus nanoparticles were verified by contact angle measurements, as compared to those of the bulk-exchange counterparts where the two types of ligands were distributed rather homogeneously on the nanoparticle surface. In a further study, a mercapto derivative of diacetylene was used as the hydrophilic ligands to prepare Janus nanoparticles by using hydrophobic hexanethiolate-protected gold nanoparticles as the starting materials. Exposure to UV irradiation led to effective covalent cross-linking between the diacetylene moieties of neighboring ligands and hence marked enhancement of the structural integrity of the Janus nanoparticles, which was attributable to the impeded surface diffusion of the thiol ligands on the nanoparticle surface, as manifested in fluorescence measurements of aged nanoparticles. More complicated bimetallic AgAu Janus nanoparticles were prepared by interfacial galvanic exchange reactions of a Langmuir-Blodgett monolayer of 1-hexanethiolate-passivated silver nanoparticles on a glass slide with gold(I)-mercaptopropanediol complex in a water/ethanol solution. The resulting nanoparticles exhibited an asymmetrical distribution not only of the organic capping ligands on the nanoparticle surface but also of the metal elements in the nanoparticle cores, in contrast to the bulk-exchange counterparts where these distributions were homogeneous within the nanoparticles, as manifested in contact angle, UV--vis, XPS, and TEM measurements. More interestingly, the electrocatalytic performance of the Janus nanoparticles was markedly better than the bulk-exchange ones, suggesting that the segregated distribution of the polar ligands from the apolar ones might further facilitate charge transfer from Ag to Au in the nanoparticle cores, leading to additional improvement of the adsorption and reduction of oxygen. This interfacial protocol was then adopted to prepare trimetallic Ag AuPt Neapolitan nanoparticles by two sequential galvanic exchange reactions of 1-hexanethiolate-capped silver nanoparticles with gold(I)-thiomalic acid and platinum(II)-hexanethiolate complexes. As both reactions were confined to an interface, the Au and Pt elements were situated on two opposite poles of the original Ag nanoparticles, which was clearly manifested in elemental mapping of the nanoparticles, and consistent with the damping and red-shift of the nanoparticle surface plasmon resonance. As nanoscale analogs to conventional amphiphilic molecules, the resulting Janus nanoparticles were found to form oil-in-water micelle-like or water-in-oil reverse micelle-like superparticulate structures depending on the solvent media. These unique characteristics were exploited for the effective transfer of diverse guest nanoparticles between organic and water phase. The transfer of hydrophobic nanoparticles from organic to water media or water-soluble nanoparticles to the organic phase was evidenced by TEM, DLS, UV-Vis, and PL measurements. In particular, line scans based on EDS analysis showed that the vesicle-like structures consisted of multiple layers of the Janus nanoparticles, which encapsulated the guest nanoparticles in the cores. The results highlight the unique effectiveness of using Janus nanoparticles in the formation of functional nanocomposites. Part of the dissertation research was also devoted to graphene quantum dots (GQDs)-supported platinum (Pt/G) nanoparticles and their electrocatalytic activity in oxygen reduction reaction. These Pt/G nanocomposites were prepared by a hydrothermal procedure at controlled temperatures. Spectroscopic measurements based on FTIR, Raman and XPS confirmed the formation of various oxygenated structural defects on GQDs and the variation of their concentrations with the hydrothermal conditions. Interestingly, electrocatalytic activity of GQD/Pt composites exhibited a volcano-shaped variation with the GQD structural defects, with the best identified as the samples prepared at 160 °C for 6 h where the mass activity was found to meet the DOE target for 2015. This remarkable performance was accounted for by the deliberate manipulation of the adsorption of oxygen and reaction intermediates on platinum by the GQD structural defects through partial charge transfer. The strategy presented herein may offer a new paradigm in the design and engineering of nanoparticle catalysts for fuel cell electrochemistry. In addition, studies were also carried out to study intervalence charge transfer between ferrocenyl moieties bonded on carbon nanoparticle surfaces by diazonium reaction. Electrochemical studies exhibited two pairs of voltammetric waves with a difference of their formal potentials at about 78 mV, suggesting nanoparticle-mediated intraparticle charge delocalization at mixed valence as a result of the strong core-ligand covalent bonds and the conductive sp 2 carbon matrix of the graphitic cores. Consistent behaviors were observed in near-infrared measurements, indicating that the particles behaved analogously to a Class I/II mixed-valence compound.

Enhancement of in-vitro drug dissolution of ketoconazole for its optimal in-vivo absorption using Nanoparticles and Solid Dispersion forms of the drug

NASA Astrophysics Data System (ADS)

Syed, Mohammed Irfan

Ketoconazole is one of the most widely prescribed oral antifungal drugs for the systemic treatment of various fungal infections. However, due its hydrophobic nature and poor solubility profiles in the gastro-intestinal fluids, variations in its bioavailability have been documented. Therefore, to enhance its dissolution in the biological fluids, this study was initiated to develop and evaluate Nanoparticles and Solid Dispersion forms of the drug. Nanoparticles of ketoconazole were developed by Wet Bead Milling technique using PVP-10k as the stabilizing material at a weight ratio of (2:1). Solid dispersion powder was prepared by Hot Melt method using PEG-8000 at a weight ratio of (1:2). A commercial product containing 200mg of ketoconazole tablet and pure drug powder were used as the control for comparison purposes. The dissolution studies were carried out in SGF, SIF, USP; and SIF with 0.2% sodium lauryl sulfate using the USP-II method for a 2 hours period. Physical characterizations were carried out using SEM, DSC, XRD and FTIR studies. Wet Bead Milling method yielded nanoparticles in the particles size range of (100-300nm.). First all samples were evaluated for their in-vitro dissolution in SGF at pH=1.2. After 15 minutes, the amounts of drug dissolved were observed to be 27% from both the pure powder and commercial tablet (control), 29% from solid dispersion and 100% from the Nanoparticles dosage form. This supports the fact that Nanoparticles had a strong influence on the dissolution rate of the drug and exhibited much faster dissolution of ketoconazole. When the same formulations were studied in the SIF, USP medium, the control formulation gave 3%, solid dispersion 8% and Nanoparticles 8% drug dissolution after 2 hours period. This could be because the weakly basic ketoconazole drug remained un-dissociated in the alkaline medium. Since this medium was unable to clearly distinguish the dissolution profiles from different formulation of the drug, the SIF solution was modified to include 0.02%, 0.05% and 0.1% sodium lauryl sulfate. Here, after 2 hours, the amount of drug dissolved was calculated to be 10% from controls, 21% from solid dispersion and 36% from nanoparticles in SIF with 0.02% SLS. Drug release was 20% from controls, 41% from solid dispersion and 52% from nanoparticle formulation in SIF with 0.05% SLS. Whereas amount of drug released in SIF with 0.1% SLS showed 21% from the control, 62% from solid dispersion and 85% from Nanoparticles respectively. This data supports that the ketoconazole Nanoparticles and its solid-dispersion exhibit many fold increase in dissolution of the drug, which could lead to a less variable and enhanced in-vivo drug absorption profiles. In addition, the data from the Physical Characterization (DSC, XRD and FTIR) supports that there were no interaction within the ingredients occurred in Nanoparticles and solid-dispersion formulations of the drug sample. Wet Bead Milling and Hot Melt methods proved useful in developing the Nanoparticles and solid dispersion form of ketoconazole. Results from particle size analysis were in correlation with data obtained from Scanning electron Microscopy and size of the nanoparticles was below 100nm. The dissolution studies with the modified simulated intestinal fluid (SIF) exhibited several fold increase in the dissolution of the drug compared to the pure drug powder and the commercial products used as the control. Also, the results from the physical characterization studies clearly support the stability of ketoconazole in both of these formulations.

Multi-Ferroic Polymer Nanoparticle Composites for Next Generation Metamaterials

DTIC Science & Technology

2015-12-18

silver nanoparticles and elastomeric fibres. Nat Nanotechnol...Conductors Based on Block Copolymer Silver Nanoparticle Composites. Acs Nano 2015, 9 (1), 336-344. 2. (a) Yang, T. I.; Brown, R. N. C.; Kempel, L. C...Brown, R. N. C.; CKempel, L.; Kofinas, P., Controlled synthesis of core-shell iron-silica nanoparticles and their magneto-dielectric properties

Study of Chemistry and Structure-Property Relationship on Tunable Plasmonic Nanostructures

NASA Astrophysics Data System (ADS)

Jing, Hao

In this dissertation, the rational design and controllable fabrication of an array of novel plasmonic nanostructures with geometrically tunable optical properties are demonstrated, including metal-semiconductor hybrid hetero-nanoparticles, bimetallic noble metal nanoparticles and hollow nanostructures (nanobox and nanocage). Firstly, I have developed a robust wet chemistry approach to the geometry control of Ag-Cu2O core-shell nanoparticles through epitaxial growth of Cu2O nanoshells on the surfaces of various Ag nanostructures, such as quasi-spherical nanoparticles, nanocubes, and nanocuboids. Precise control over the core and the shell geometries enables me to develop detailed, quantitative understanding of how the Cu2O nanoshells introduce interesting modifications to the resonance frequencies and the extinction spectral line shapes of multiple plasmon modes of the Ag cores. Secondly, I present a detailed and systematic study of the controlled overgrowth of Pd on Au nanorods. The overgrowth of Pd nanoshells with fine-controlled dimensions and architectures on single-crystalline Au nanorods through seed-mediated growth protocol in the presence of various surfactants is investigated. Thirdly, I have demonstrated that creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Through site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, I have controllably fabricated nanorice and nanodumbbell particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high index facets abundant on the particle surfaces. And the nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time-resolved plasmon-enhanced spectroscopic measurements, such as surface-enhanced Raman scattering (SERS). Last but not least, I have demonstrated that the capability of geometry control over Ag-Pd bimetallic hollow nanostructures through nanoscale galvanic replacement can be greatly enhanced by the use of appropriate mild reducing agents, such as ascorbic acid and formaldehyde. With the aid of mild reducing agents, we have been able to fine-tailor the compositions, interior architectures, and surface morphologies of Ag-Pd bimetallic hollow nanoparticles with increased structural complexity through surface ligand-free galvanic replacement processes at room temperature. This reducing agent-mediated galvanic replacement provides a unique way of achieving both enhanced optical tunability and optimized catalytic activities through deliberate control over the geometries of complex Ag-Pd bimetallic nanoparticles.

Effects of curcumin-loaded PLGA nanoparticles on the RG2 rat glioma model.

PubMed

Orunoğlu, Merdan; Kaffashi, Abbas; Pehlivan, Sibel Bozdağ; Şahin, Selma; Söylemezoğlu, Figen; Oğuz, Kader Karli; Mut, Melike

2017-09-01

Curcumin, the active ingredient of turmeric, has a remarkable antitumor activity against various cancers, including glioblastoma. However, it has poor absorption and low bioavailability; thus, to cross the blood-brain barrier and reach tumor tissue, it needs to be transferred to tumor site by special drug delivery systems, such as nanoparticles. We aimed to evaluate the antitumor activity of curcumin on glioblastoma tissue in the rat glioma-2 (RG2) tumor model when it is loaded on poly(lactic-co-glycolic acid)-1,2-distearoyl-glycerol-3-phospho-ethanolamine-N-[methoxy (polyethylene glycol)-2000] ammonium salt (PLGA-DSPE-PEG) hybrid nanoparticles. Glioblastoma was induced in 42 adult female Wistar rats (250-300g) by RG2 tumor model. The curcumin-loaded nanoparticles were injected by intravenous (n=6) or intratumoral route (n=6). There were five control groups, each containing six rats. First control group was not applied any treatment. The remaining four control groups were given empty nanoparticles or curcumin alone by intravenous or intratumoral route, respectively. The change in tumor volume was assessed by magnetic resonance imaging and histopathology before and 5days after drug injections. Tumor size decreased significantly after 5days of intratumoral injection of curcumin-loaded nanoparticle (from 66.6±44.6 to 34.9±21.7mm 3 , p=0.028), whereas it significantly increased in nontreated control group (from 33.9±21.3 to 123.7±41.1mm 3 , p=0.036) and did not significantly change in other groups (p>0.05 for all). In this in vivo experimental model, intratumoral administration of curcumin-loaded PLGA-DSPE-PEG hybrid nanoparticles was effective against glioblastoma. Curcumine-loaded nanoparticles may have potential application in chemotherapy of glioblastoma. Copyright © 2017 Elsevier B.V. All rights reserved.

Spatiotemporal Targeting of a Dual-Ligand Nanoparticle to Cancer Metastasis

PubMed Central

Doolittle, Elizabeth; Peiris, Pubudu M.; Doron, Gilad; Goldberg, Amy; Tucci, Samantha; Rao, Swetha; Shah, Shruti; Sylvestre, Meilyn; Govender, Priya; Turan, Oguz; Lee, Zhenghong; Schiemann, William P.; Karathanasis, Efstathios

2015-01-01

Various targeting strategies and ligands have been employed to direct nanoparticles to tumors that upregulate specific cell-surface molecules. However, tumors display a dynamic, heterogeneous microenvironment, which undergoes spatiotemporal changes including the expression of targetable cell-surface biomarkers. Here, we investigated a dual-ligand nanoparticle to effectively target two receptors overexpressed in aggressive tumors. By using two different chemical specificities, the dual-ligand strategy considered the spatiotemporal alterations in the expression patterns of the receptors in cancer sites. As a case study, we used two mouse models of metastasis of triple-negative breast cancer using the MDA-MB-231 and 4T1 cells. The dual-ligand system utilized two peptides targeting P-selectin and αvβ3 integrin, which are functionally linked to different stages of the development of metastatic disease at a distal site. Using in vivo multimodal imaging and post mortem histological analyses, this study shows that the dual-ligand nanoparticle effectively targeted metastatic disease that was otherwise missed by single-ligand strategies. The dual-ligand nanoparticle was capable of capturing different metastatic sites within the same animal that overexpressed either receptor or both of them. Furthermore, the highly efficient targeting resulted in 22% of the injected dual-ligand nanoparticles being deposited in early-stage metastases within 2 h after injection. PMID:26203676

Multistage Targeting Strategy Using Magnetic Composite Nanoparticles for Synergism of Photothermal Therapy and Chemotherapy.

PubMed

Wang, Yi; Wei, Guoqing; Zhang, Xiaobin; Huang, Xuehui; Zhao, Jingya; Guo, Xing; Zhou, Shaobing

2018-03-01

Mitochondrial-targeting therapy is an emerging strategy for enhanced cancer treatment. In the present study, a multistage targeting strategy using doxorubicin-loaded magnetic composite nanoparticles is developed for enhanced efficacy of photothermal and chemical therapy. The nanoparticles with a core-shell-SS-shell architecture are composed of a core of Fe 3 O 4 colloidal nanocrystal clusters, an inner shell of polydopamine (PDA) functionalized with triphenylphosphonium (TPP), and an outer shell of methoxy poly(ethylene glycol) linked to the PDA by disulfide bonds. The magnetic core can increase the accumulation of nanoparticles at the tumor site for the first stage of tumor tissue targeting. After the nanoparticles enter the tumor cells, the second stage of mitochondrial targeting is realized as the mPEG shell is detached from the nanoparticles by redox responsiveness to expose the TPP. Using near-infrared light irradiation at the tumor site, a photothermal effect is generated from the PDA photosensitizer, leading to a dramatic decrease in mitochondrial membrane potential. Simultaneously, the loaded doxorubicin can rapidly enter the mitochondria and subsequently damage the mitochondrial DNA, resulting in cell apoptosis. Thus, the synergism of photothermal therapy and chemotherapy targeting the mitochondria significantly enhances the cancer treatment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spatiotemporal Targeting of a Dual-Ligand Nanoparticle to Cancer Metastasis.

PubMed

Doolittle, Elizabeth; Peiris, Pubudu M; Doron, Gilad; Goldberg, Amy; Tucci, Samantha; Rao, Swetha; Shah, Shruti; Sylvestre, Meilyn; Govender, Priya; Turan, Oguz; Lee, Zhenghong; Schiemann, William P; Karathanasis, Efstathios

2015-08-25

Various targeting strategies and ligands have been employed to direct nanoparticles to tumors that upregulate specific cell-surface molecules. However, tumors display a dynamic, heterogeneous microenvironment, which undergoes spatiotemporal changes including the expression of targetable cell-surface biomarkers. Here, we investigated a dual-ligand nanoparticle to effectively target two receptors overexpressed in aggressive tumors. By using two different chemical specificities, the dual-ligand strategy considered the spatiotemporal alterations in the expression patterns of the receptors in cancer sites. As a case study, we used two mouse models of metastasis of triple-negative breast cancer using the MDA-MB-231 and 4T1 cells. The dual-ligand system utilized two peptides targeting P-selectin and αvβ3 integrin, which are functionally linked to different stages of the development of metastatic disease at a distal site. Using in vivo multimodal imaging and post mortem histological analyses, this study shows that the dual-ligand nanoparticle effectively targeted metastatic disease that was otherwise missed by single-ligand strategies. The dual-ligand nanoparticle was capable of capturing different metastatic sites within the same animal that overexpressed either receptor or both of them. Furthermore, the highly efficient targeting resulted in 22% of the injected dual-ligand nanoparticles being deposited in early-stage metastases within 2 h after injection.

Biosynthesis of extracellular and intracellular gold nanoparticles by Aspergillus fumigatus and A. flavus.

PubMed

Gupta, Saurabh; Bector, Shruti

2013-05-01

Green chemistry is a boon for the development of safe, stable and ecofriendly nanostructures using biological tools. The present study was carried out to explore the potential of selected fungal strains for biosynthesis of intra- and extracellular gold nanostructures. Out of the seven cultures, two fungal strains (SBS-3 and SBS-7) were selected on the basis of development of dark pink colour in cell free supernatant and fungal beads, respectively indicative of extra- and intracellular gold nanoparticles production. Both biomass associated and cell free gold nanoparticles were characterized using X-ray diffractogram (XRD) analysis and transmission electron microscopy (TEM). XRD analysis confirmed crystalline, face-centered cubic lattice of metallic gold nanoparticles along with average crystallite size. A marginal difference in average crystallite size of extracellular (17.76 nm) and intracellular (26 and 22 nm) Au-nanostructures was observed using Scherrer equation. In TEM, a variety of shapes (triangles, spherical, hexagonal) were observed in both extra- and intracellular nanoparticles. 18S rRNA gene sequence analysis by multiple sequence alignment (BLAST) indicated 99 % homology of SBS-3 to Aspergillus fumigatus with 99 % alignment coverage and 98 % homology of SBS-7 to Aspergillus flavus with 98 % alignment coverage respectively. Native-PAGE and activity staining further confirmed enzyme linked synthesis of gold nanoparticles.

Direct Measurement of the Surface Energy of Bimetallic Nanoparticles: Evidence of Vegard's Rulelike Dependence.

PubMed

Chmielewski, Adrian; Nelayah, Jaysen; Amara, Hakim; Creuze, Jérôme; Alloyeau, Damien; Wang, Guillaume; Ricolleau, Christian

2018-01-12

We use in situ transmission electron microscopy to monitor in real time the evaporation of gold, copper, and bimetallic copper-gold nanoparticles at high temperature. Besides, we extend the Kelvin equation to two-component systems to predict the evaporation rates of spherical liquid mono- and bimetallic nanoparticles. By linking this macroscopic model to experimental TEM data, we determine the surface energies of pure gold, pure copper, Cu_{50}Au_{50}, and Cu_{25}Au_{75} nanoparticles in the liquid state. Our model suggests that the surface energy varies linearly with the composition in the liquid Cu-Au nanoalloy; i.e., it follows a Vegard's rulelike dependence. To get atomic-scale insights into the thermodynamic properties of Cu-Au alloys on the whole composition range, we perform Monte Carlo simulations employing N-body interatomic potentials. These simulations at a microscopic level confirm the Vegard's rulelike behavior of the surface energy obtained from experiments combined with macroscopic modeling.

Stability and electrostatics of mercaptoundecanoic acid-capped gold nanoparticles with varying counterion size.

PubMed

Laaksonen, Timo; Ahonen, Päivi; Johans, Christoffer; Kontturi, Kyösti

2006-10-13

The solubility of charged nanoparticles is critically dependent on pH. However, the concentration range available with bases such as NaOH is quite narrow, since the particles precipitate due to compression of the electric double layer when the ionic strength is increased. The stability of mercaptoundecanoic acid-capped Au nanoparticles is studied at a set pH using the hydroxide as base and different cations of various sizes. The counterions used are sodium (Na(+)), tetramethylammonium (TMA(+)), tetraethylammonium (TEA(+)), and tetrabutylammonium (TBA(+)). The particles precipitate in the 70-90 mM range with Na(+) as the counterion, but with quaternary ammonium hydroxides the particles are stable even in concentrations exceeding 1 M. The change in solubility is linked to a strongly adsorbed layer on the surface of the ligand shell of the nanoparticles. The increased concentration range obtained with TEAOH is further used to facilitate thiol exchange which occurs at a greater extent than would be achieved in NaOH solution.

Direct Measurement of the Surface Energy of Bimetallic Nanoparticles: Evidence of Vegard's Rulelike Dependence

NASA Astrophysics Data System (ADS)

Chmielewski, Adrian; Nelayah, Jaysen; Amara, Hakim; Creuze, Jérôme; Alloyeau, Damien; Wang, Guillaume; Ricolleau, Christian

2018-01-01

We use in situ transmission electron microscopy to monitor in real time the evaporation of gold, copper, and bimetallic copper-gold nanoparticles at high temperature. Besides, we extend the Kelvin equation to two-component systems to predict the evaporation rates of spherical liquid mono- and bimetallic nanoparticles. By linking this macroscopic model to experimental TEM data, we determine the surface energies of pure gold, pure copper, Cu50 Au50 , and Cu25 Au75 nanoparticles in the liquid state. Our model suggests that the surface energy varies linearly with the composition in the liquid Cu-Au nanoalloy; i.e., it follows a Vegard's rulelike dependence. To get atomic-scale insights into the thermodynamic properties of Cu-Au alloys on the whole composition range, we perform Monte Carlo simulations employing N -body interatomic potentials. These simulations at a microscopic level confirm the Vegard's rulelike behavior of the surface energy obtained from experiments combined with macroscopic modeling.

Attachment of an anti-MUC1 monoclonal antibody to 5-FU loaded BSA nanoparticles for active targeting of breast cancer cells.

PubMed

Kouchakzadeh, Hasan; Shojaosadati, Seyed Abbas; Mohammadnejad, Javad; Paknejad, Malihe; Rasaee, Mohammad Javad

2012-01-01

With PR81 as a murine monoclonal antibody (mAb) that was prepared against the human breast cancer, the MUC1 receptor specific targeting is possible. In this study, PR81-conjugated bovine serum albumin (BSA) nanoparticles loaded with anticancer drug 5-fluorouracil (5-FU) were developed. Enzyme linked immunosorbant assay (ELISA) results showed high immunoreactivity of PR81 mAb conjugated to nanoparticles towards MUC1 related peptide or native cancerous MUC1 and almost no cross-reaction to non-specific proteins. In vitro experiments were performed to determine the ability of this new drug delivery system on overcoming MCF-7 breast cancer cells in comparison with four other systems. The results revealed that these cell-type specific drug loaded nanoparticles could achieve more cell death as compared to when the 5-FU was used with no carriers. Stability studies of produced drug delivery system proved high immunoreactivity of conjugated PR81 even after 11 days of storage in room temperature.

Molecular Dynamics Studies of Self-Assembling Biomolecules and DNA-functionalized Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Cho, Vince Y.

This thesis is organized as following. In Chapter 2, we use fully atomistic MD simulations to study the conformation of DNA molecules that link gold nanoparticles to form nanoparticle superlattice crystals. In Chapter 3, we study the self-assembly of peptide amphiphiles (PAs) into a cylindrical micelle fiber by using CGMD simulations. Compared to fully atomistic MD simulations, CGMD simulations prove to be computationally cost-efficient and reasonably accurate for exploring self-assembly, and are used in all subsequent chapters. In Chapter 4, we apply CGMD methods to study the self-assembly of small molecule-DNA hybrid (SMDH) building blocks into well-defined cage-like dimers, and reveal the role of kinetics and thermodynamics in this process. In Chapter 5, we extend the CGMD model for this system and find that the assembly of SMDHs can be fine-tuned by changing parameters. In Chapter 6, we explore superlattice crystal structures of DNA-functionalized gold nanoparticles (DNA-AuNP) with the CGMD model and compare the hybridization.

Target Nanoparticles for Therapy - SANS and DLS of Drug Carrier Liposomes and Polymer Nanoparticles

NASA Astrophysics Data System (ADS)

Nawroth, T.; Johnson, R.; Krebs, L.; Khoshakhlagh, P.; Langguth, P.; Hellmann, N.; Goerigk, G.; Boesecke, P.; Bravin, A.; Le Duc, G.; Szekely, N.; Schweins, R.

2016-09-01

T arget Nano-Pharmaceutics shall improve therapy and diagnosis of severe diseases, e.g. cancer, by individual targeting of drug-loaded nano-pharmaceuticals towards cancer cells, and drug uptake receptors in other diseases. Specific ligands, proteins or cofactors, which are recognized by the diseased cells or cells of food and drug uptake, are bound to the nanoparticle surface, and thus capable of directing the drug carriers. The strategy has two branches: a) for parenteral cancer medicine a ligand set (2-5 different, surface-linked) are selected according to the biopsy analysis of the patient tissue e.g. from tumor.; b) in the oral drug delivery part the drug transport is enforced by excipients/ detergents in combination with targeting materials for cellular receptors resulting in an induced drug uptake. Both targeting nanomaterials are characterized by a combination of SANS + DLS and SAXS or ASAXS in a feedback process during development by synthesis, nanoparticle assembly and formulation.

Building superlattices from individual nanoparticles via template-confined DNA-mediated assembly

NASA Astrophysics Data System (ADS)

Lin, Qing-Yuan; Mason, Jarad A.; Li, Zhongyang; Zhou, Wenjie; O’Brien, Matthew N.; Brown, Keith A.; Jones, Matthew R.; Butun, Serkan; Lee, Byeongdu; Dravid, Vinayak P.; Aydin, Koray; Mirkin, Chad A.

2018-02-01

DNA programmable assembly has been combined with top-down lithography to construct superlattices of discrete, reconfigurable nanoparticle architectures on a gold surface over large areas. Specifically, the assembly of individual colloidal plasmonic nanoparticles with different shapes and sizes is controlled by oligonucleotides containing “locked” nucleic acids and confined environments provided by polymer pores to yield oriented architectures that feature tunable arrangements and independently controllable distances at both nanometer- and micrometer-length scales. These structures, which would be difficult to construct by other common assembly methods, provide a platform to systematically study and control light-matter interactions in nanoparticle-based optical materials. The generality and potential of this approach are explored by identifying a broadband absorber with a solvent polarity response that allows dynamic tuning of visible light absorption.

Drug release from nanoparticles embedded in four different nanofibrillar cellulose aerogels.

PubMed

Valo, Hanna; Arola, Suvi; Laaksonen, Päivi; Torkkeli, Mika; Peltonen, Leena; Linder, Markus B; Serimaa, Ritva; Kuga, Shigenori; Hirvonen, Jouni; Laaksonen, Timo

2013-09-27

Highly porous nanocellulose aerogels prepared by freeze-drying from various nanofibrillar cellulose (NFC) hydrogels are introduced as nanoparticle reservoirs for oral drug delivery systems. Here we show that beclomethasone dipropionate (BDP) nanoparticles coated with amphiphilic hydrophobin proteins can be well integrated into the NFC aerogels. NFCs from four different origins are introduced and compared to microcrystalline cellulose (MCC). The nanocellulose aerogel scaffolds made from red pepper (RC) and MCC release the drug immediately, while bacterial cellulose (BC), quince seed (QC) and TEMPO-oxidized birch cellulose-based (TC) aerogels show sustained drug release. Since the release of the drug is controlled by the structure and interactions between the nanoparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These nanocomposite structures can be very useful in many pharmaceutical nanoparticle applications and open up new possibilities as carriers for controlled drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

Minimal-length Synthetic shRNAs Formulated with Lipid Nanoparticles are Potent Inhibitors of Hepatitis C Virus IRES-linked Gene Expression in Mice

PubMed Central

Dallas, Anne; Ilves, Heini; Shorenstein, Joshua; Judge, Adam; Spitler, Ryan; Contag, Christopher; Wong, Suet Ping; Harbottle, Richard P; MacLachlan, Ian; Johnston, Brian H

2013-01-01

We previously identified short synthetic shRNAs (sshRNAs) that target a conserved hepatitis C virus (HCV) sequence within the internal ribosome entry site (IRES) of HCV and potently inhibit HCV IRES-linked gene expression. To assess in vivo liver delivery and activity, the HCV-directed sshRNA SG220 was formulated into lipid nanoparticles (LNP) and injected i.v. into mice whose livers supported stable HCV IRES-luciferase expression from a liver-specific promoter. After a single injection, RNase protection assays for the sshRNA and 3H labeling of a lipid component of the nanoparticles showed efficient liver uptake of both components and long-lasting survival of a significant fraction of the sshRNA in the liver. In vivo imaging showed a dose-dependent inhibition of luciferase expression (>90% 1 day after injection of 2.5 mg/kg sshRNA) with t1/2 for recovery of about 3 weeks. These results demonstrate the ability of moderate levels of i.v.-injected, LNP-formulated sshRNAs to be taken up by liver hepatocytes at a level sufficient to substantially suppress gene expression. Suppression is rapid and durable, suggesting that sshRNAs may have promise as therapeutic agents for liver indications. PMID:24045712

Microstructure and rheology of thermoreversible nanoparticle gels.

PubMed

Ramakrishnan, S; Zukoski, C F

2006-08-29

Naïve mode coupling theory is applied to particles interacting with short-range Yukawa attractions. Model results for the location of the gel line and the modulus of the resulting gels are reduced to algebraic equations capturing the effects of the range and strength of attraction. This model is then applied to thermo reversible gels composed of octadecyl silica particles suspended in decalin. The application of the model to the experimental system requires linking the experimental variable controlling strength of attraction, temperature, to the model strength of attraction. With this link, the model predicts temperature and volume fraction dependencies of gelation and modulus with five parameters: particle size, particle volume fraction, overlap volume of surface hairs, and theta temperature. In comparing model predictions with experimental results, we first observe that in these thermal gels there is no evidence of clustering as has been reported in depletion gels. One consequence of this observation is that there are no additional adjustable parameters required to make quantitative comparisons between experimental results and model predictions. Our results indicate that the naïve mode coupling approach taken here in conjunction with a model linking temperature to strength of attraction provides a robust approach for making quantitative predictions of gel mechanical properties. Extension of model predictions to additional experimental systems requires linking experimental variables to the Yukawa strength and range of attraction.

NANOTECHNOLOGY: A NOVEL APPROACH TO PREVENT BIOCIDE LEACHING

EPA Science Inventory

This project will demonstrate the environmental benefits of introducing biocide into wood using hydrophobic nanoparticles as a delivery vehicle and controlled release device for organic and inorganic biocides. The primary benefits expected from use of nanoparticles as controll...

Engineered Hybrid Nanoparticles for On-Demand Diagnostics and Therapeutics.

PubMed

Nguyen, Kim Truc; Zhao, Yanli

2015-12-15

Together with the simultaneous development of nanomaterials and molecular biology, the bionano interface brings about various applications of hybrid nanoparticles in nanomedicine. The hybrid nanoparticles not only present properties of the individual components but also show synergistic effects for specialized applications. Thus, the development of advanced hybrid nanoparticles for targeted and on-demand diagnostics and therapeutics of diseases has rapidly become a hot research topic in nanomedicine. The research focus is to fabricate novel classes of programmable hybrid nanoparticles that are precisely engineered to maximize drug concentrations in diseased cells, leading to enhanced efficacy and reduced side effects of chemotherapy for the disease treatment. In particular, the hybrid nanoparticle platforms can simultaneously target diseased cells, enable the location to be imaged by optical methods, and release therapeutic drugs to the diseased cells by command. This Account specially discusses the rational fabrication of integrated hybrid nanoparticles and their applications in diagnostics and therapeutics. For diagnostics applications, hybrid nanoparticles can be utilized as imaging agents that enable detailed visualization at the molecular level. By the use of suitable targeting ligands incorporated on the nanoparticles, targeted optical imaging may be feasible with improved performance. Novel imaging techniques such as multiphoton excitation and photoacoustic imaging using near-infrared light have been developed using the intrinsic properties of particular nanoparticles. The use of longer-wavelength excitation sources allows deeper penetration into the human body for disease diagnostics and at the same time reduces the adverse effects on normal tissues. Furthermore, multimodal imaging techniques have been achieved by combining several types of components in nanoparticles, offering higher accuracy and better spatial views, with the aim of detecting life-threatening diseases before symptoms appear. For therapeutics applications, various nanoparticle-based treatment methods such as photodynamic therapy, drug delivery, and gene delivery have been developed. The intrinsic ability of organic nanoparticles to generate reactive oxygen species has been utilized for photodynamic therapy, and mesoporous silica nanoparticles have been widely used for drug loading and controlled delivery. Herein, the development of controlled-release systems that can specifically deliver drug molecules to target cells and release then upon triggering is highlighted. By control of the release of loaded drug molecules at precise sites (e.g., cancer cells or malignant tumors), side effects of the drugs are minimized. This approach provides better control and higher efficacy of drugs in the human body. Future personalized medicine is also feasible through gene delivery methods. Specific DNA/RNA-carrying nanoparticles are able to deliver them to target cells to obtain desired properties. This development may create an evolution in current medicine, leading to more personalized healthcare systems that can reduce the population screening process and also the duration of drug evaluation. Furthermore, nanoparticles can be incorporated with various components that can be used for simultaneous diagnostics and therapeutics. These multifunctional theranostic nanoparticles enable real-time monitoring of treatment process for more efficient therapy.

Layer-by-Layer-Assembled AuNPs-Decorated First-Generation Poly(amidoamine) Dendrimer with Reduced Graphene Oxide Core as Highly Sensitive Biosensing Platform with Controllable 3D Nanoarchitecture for Rapid Voltammetric Analysis of Ultratrace DNA Hybridization.

PubMed

Jayakumar, Kumarasamy; Camarada, María Belén; Dharuman, Venkataraman; Rajesh, Rajendiran; Venkatesan, Rengarajan; Ju, Huangxian; Maniraj, Mahalingam; Rai, Abhishek; Barman, Sudipta Roy; Wen, Yangping

2018-06-27

The structure and electrochemical properties of layer-by-layer-assembled gold nanoparticles (AuNPs)-decorated first-generation (G1) poly(amidoamine) dendrimer (PD) with reduced graphene oxide (rGO) core as a highly sensitive and label-free biosensing platform with a controllable three-dimensional (3D) nanoarchitecture for the rapid voltammetric analysis of DNA hybridization at ultratrace levels were characterized. Mercaptopropinoic acid (MPA) was self-assembled onto Au substrate, then GG1PD formed by the covalent functionalization between the amino terminals of G1PD and carboxyl terminals of rGO was covalently linked onto MPA, and finally AuNPs were decorated onto GG1PD by strong physicochemical interaction between AuNPs and -OH of rGO in GG1PD, which was characterized through different techniques and confirmed by computational calculation. This 3D controllable thin-film electrode was optimized and evaluated using [Fe(CN) 6 ] 3-/4- as the redox probe and employed to covalently immobilize thiol-functionalized single-stranded DNA as biorecognition element to form the DNA nanobiosensor, which achieved fast, ultrasensitive, and high-selective differential pulse voltammetric analysis of DNA hybridization in a linear range from 1 × 10 -6 to 1 × 10 -13 g m -1 with a low detection limit of 9.07 × 10 -14 g m -1 . This work will open a new pathway for the controllable 3D nanoarchitecture of the layer-by-layer-assembled metal nanoparticles-functionalized lower-generation PD with two-dimensional layered nanomaterials as cores that can be employed as ultrasensitive and label-free nanobiodevices for the fast diagnosis of specific genome diseases in the field of biomedicine.

Carbothermal shock synthesis of high-entropy-alloy nanoparticles

NASA Astrophysics Data System (ADS)

Yao, Yonggang; Huang, Zhennan; Xie, Pengfei; Lacey, Steven D.; Jacob, Rohit Jiji; Xie, Hua; Chen, Fengjuan; Nie, Anmin; Pu, Tiancheng; Rehwoldt, Miles; Yu, Daiwei; Zachariah, Michael R.; Wang, Chao; Shahbazian-Yassar, Reza; Li, Ju; Hu, Liangbing

2018-03-01

The controllable incorporation of multiple immiscible elements into a single nanoparticle merits untold scientific and technological potential, yet remains a challenge using conventional synthetic techniques. We present a general route for alloying up to eight dissimilar elements into single-phase solid-solution nanoparticles, referred to as high-entropy-alloy nanoparticles (HEA-NPs), by thermally shocking precursor metal salt mixtures loaded onto carbon supports [temperature ~2000 kelvin (K), 55-millisecond duration, rate of ~105 K per second]. We synthesized a wide range of multicomponent nanoparticles with a desired chemistry (composition), size, and phase (solid solution, phase-separated) by controlling the carbothermal shock (CTS) parameters (substrate, temperature, shock duration, and heating/cooling rate). To prove utility, we synthesized quinary HEA-NPs as ammonia oxidation catalysts with ~100% conversion and >99% nitrogen oxide selectivity over prolonged operations.

Nanoparticles in Polymers: Assembly, Rheology and Properties

NASA Astrophysics Data System (ADS)

Rao, Yuanqiao

Inorganic nanoparticles have the potential of providing functionalities that are difficult to realize using organic materials; and nanocomposites is an effective mean to impart processibility and construct bulk materials with breakthrough properties. The dispersion and assembly of nanoparticles are critical to both processibility and properties of the resulting product. In this talk, we will discuss several methods to control the hierarchical structure of nanoparticles in polymers and resulting rheological, mechanical and optical properties. In one example, polymer-particle interaction and secondary microstructure were designed to provide a low viscosity composition comprising exfoliated high aspect ratio clay nanoparticles; in another example, the microstructure control through templates was shown to enable unique thermal mechanical and optical properties. Jeff Munro, Stephanie Potisek, Phillip Hustad; all of the Dow Chemical Company are co-authors.

Colloidal aluminum nanoparticles with tunable localized surface plasmon resonances for energy applications

NASA Astrophysics Data System (ADS)

Cheng, Yan; Smith, Kenneth; Arinze, Ebuka; Nyirjesy, Gabrielle; Bragg, Arthur; Thon, Susanna

Localized surface plasmon resonances (LSPRs) of noble metal nanoparticles are of interest for energy applications due to their visible and near infrared wavelength sensitivity. However, application of these materials in optoelectronic devices is limited by their rarity and high cost. Earth-abundant, inexpensive and non-toxic aluminum is a promising alternative material with a plasmon resonance that can also be tuned via size-, shape- and surface-oxide-control. Here, we employ solution-processed methods to synthesize stable colloidal aluminum nanoparticles. We systematically investigate parameters in the synthesis that control size, shape and oxidation of the aluminum nanoparticles and tune their LSPRs over the ultraviolet and visible spectral regions. We optically characterize the nanoparticle solutions and evaluate their potential for future integration into photovoltaic, photocatalytic and photosensing systems.

Aloe barbadensis Miller mediated green synthesis of mono-disperse copper oxide nanoparticles: Optical properties

NASA Astrophysics Data System (ADS)

Gunalan, Sangeetha; Sivaraj, Rajeshwari; Venckatesh, Rajendran

2012-11-01

In this paper, we report on the synthesis of nanostructured copper oxide particles by both chemical and biological method. A facile and efficient synthesis of copper oxide nanoparticles was carried out with controlled surface properties via green chemistry approach. The CuO nanoparticles synthesized are monodisperse and versatile and were characterized with the help of UV-Vis, PL, FT-IR, XRD, SEM, and TEM techniques. The particles are crystalline in nature and average sizes were between 15 and 30 nm. The morphology of the nanoparticles can be controlled by tuning the amount of Aloe vera extract. This new eco-friendly approach of synthesis is a novel, cheap, and convenient technique suitable for large scale commercial production and health related applications of CuO nanoparticles.

Experimental and theoretical investigation of intratumoral nanoparticle distribution to enhance magnetic nanoparticle hyperthermia

NASA Astrophysics Data System (ADS)

Attaluri, Anilchandra

Magnetic nanoparticles have gained prominence in recent years for use in clinical applications such as imaging, drug delivery, and hyperthermia. Magnetic nanoparticle hyperthermia is a minimally invasive and effective approach for confined heating in tumors with little collateral damage. One of the major problems in the field of magnetic nanoparticle hyperthermia is irregular heat distribution in tumors which caused repeatable heat distribution quite impossible. This causes under dosage in tumor area and overheating in normal tissue. In this study, we develop a unified approach to understand magnetic nanoparticle distribution and temperature elevations in gel and tumors. A microCT imaging system is first used to visualize and quantify nanoparticle distribution in both tumors and tissue equivalent phantom gels. The microCT based nanoparticle concentration is related to specific absorption rate (SAR) of the nanoparticles and is confirmed by heat distribution experiments in tissue equivalent phantom gels. An optimal infusion protocol is identified to generate controllable and repeatable nanoparticle distribution in tumors. In vivo animal experiments are performed to measure intratumoral temperature elevations in PC3 xenograft tumors implanted in mice during magnetic nanoparticle hyperthermia. The effect of nanofluid injection parameters on the resulted temperature distribution is studied. It shows that the tumor temperatures can be elevated above 50°C using very small amounts of ferrofluid with a relatively low magnetic field. Slower ferrofluid infusion rates result in smaller nanoparticle distribution volumes in the tumors, however, it gives the much required controllability and repeatability when compared to the higher infusion rates. More nanoparticles occupy a smaller volume in the vicinity of the injection site with slower infusion rates, causing higher temperature elevations in the tumors. Based on the microCT imaging analyses of nanoparticles in tumors, a mass transport model is developed to simulate nanoparticle convection and diffusion in tumors, heat-induced tumor structural changes, as well as nanoparticle re-distribution during nanoparticle hyperthermia procedures. The modeled thermal damage induced nanoparticle redistribution predicts a 20% increase in the radius of the spherical tissue region containing nanoparticles. The developed model has demonstrated the feasibility of enhancing nanoparticle dispersion from injection sites using targeted thermal damage.

Continuous manufacturing of solid lipid nanoparticles by hot melt extrusion.

PubMed

Patil, Hemlata; Kulkarni, Vijay; Majumdar, Soumyajit; Repka, Michael A

2014-08-25

Solid lipid nanoparticles (SLN) can either be produced by hot homogenization of melted lipids at higher temperatures or by a cold homogenization process. This paper proposes and demonstrates the formulation of SLN for pharmaceutical applications by combining two processes: hot melt extrusion (HME) technology for melt-emulsification and high-pressure homogenization (HPH) for size reduction. This work aimed at developing continuous and scalable processes for SLN by mixing a lipid and aqueous phase containing an emulsifier in the extruder barrel at temperatures above the melting point of the lipid and further reducing the particle size of emulsion by HPH linked to HME in a sequence. The developed novel platform demonstrated better process control and size reduction compared to the conventional process of hot homogenization (batch process). Varying the process parameters enabled the production of SLN below 200 nm (for 60 mg/ml lipid solution at a flow rate of 100ml/min). Among the several process parameters investigated, the lipid concentration, residence time and screw design played major roles in influencing the size of the SLN. This new process demonstrates the potential use of hot melt extrusion technology for continuous and large-scale production of SLN. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnetic hydrogel nanocomposites and composite nanoparticles--a review of recent patented works.

PubMed

Daniel-da-Silva, Ana L; Carvalho, Rui S; Trindade, Tito

2013-06-01

Magnetic hydrogel nanocomposites and composite nanoparticles form a class of soft materials with remote controllable properties that have attracted great attention due to their potential use in diverse applications. These include medical applications such as controlled drug delivery, clinical imaging and cancer hyperthermia and ecological applications as well, such as wastewater treatment. The present review provides an overview of the patents disclosed and research work developed in the last decade on magnetic hydrogel nanocomposites and magnetic hydrogel composite nanoparticles envisaging the above mentioned applications. In this context, recent patented advances on chemical methods for the preparation of bulk hydrogel nanocomposites and composite nanoparticles will be reviewed.

Electrical control of Faraday rotation at a liquid-liquid interface.

PubMed

Marinescu, Monica; Kornyshev, Alexei A; Flatté, Michael E

2015-01-01

A theory is developed for the Faraday rotation of light from a monolayer of charged magnetic nanoparticles at an electrified liquid-liquid interface. The polarization fields of neighboring nanoparticles enhance the Faraday rotation. At such interfaces, and for realistic sizes and charges of nanoparticles, their adsorption-desorption can be controlled with a voltage variation<1 V, providing electrovariable Faraday rotation. A calculation based on the Maxwell-Garnett theory predicts that the corresponding redistribution of 40 nm nanoparticles of yttrium iron garnet can switch a cavity with a quality factor larger than 10(4) for light of wavelength 500 nm at normal incidence.

Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

NASA Astrophysics Data System (ADS)

Jiang, Jingkun; Chen, Da-Ren; Biswas, Pratim

2007-07-01

A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO2 nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO2 nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size.

Tuning dipolar magnetic interactions by controlling individual silica coating of iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Rivas Rojas, P. C.; Tancredi, P.; Moscoso Londoño, O.; Knobel, M.; Socolovsky, L. M.

2018-04-01

Single and fixed size core, core-shell nanoparticles of iron oxides coated with a silica layer of tunable thickness were prepared by chemical routes, aiming to generate a frame of study of magnetic nanoparticles with controlled dipolar interactions. The batch of iron oxides nanoparticles of 4.5 nm radii, were employed as cores for all the coated samples. The latter was obtained via thermal decomposition of organic precursors, resulting on nanoparticles covered with an organic layer that was subsequently used to promote the ligand exchange in the inverse microemulsion process, employed to coat each nanoparticle with silica. The amount of precursor and times of reaction was varied to obtain different silica shell thicknesses, ranging from 0.5 nm to 19 nm. The formation of the desired structures was corroborated by TEM and SAXS measurements, the core single-phase spinel structure was confirmed by XRD, and superparamagnetic features with gradual change related to dipolar interaction effects were obtained by the study of the applied field and temperature dependence of the magnetization. To illustrate that dipolar interactions are consistently controlled, the main magnetic properties are presented and analyzed as a function of center to center minimum distance between the magnetic cores.

In vivo evaluation of toxicity and antiviral activity of polyrhodanine nanoparticles by using the chicken embryo model.

PubMed

Nazaktabar, Ahmad; Lashkenari, Mohammad Soleimani; Araghi, Atefeh; Ghorbani, Mohsen; Golshahi, Hannaneh

2017-10-01

Evaluation of the potential cytotoxicity of polyrhodanine nanoparticles is an important factor for its biological applications. In current study, for the first time histopathological and biochemical analysis of polyrhodanine besides of its antiviral activity against Newcastle disease virus (NDV) were examined on chicken embryo model. Polyrhodanine was synthesized by the chemical oxidative polymerization method. The obtained nanoparticles were characterized by scanning electron microscopy (SEM), and Fourier transform infrared (FTIR). Different doses of polyrhodanine nanoparticles were injected into the albumen in 4-day-old embryonic eggs for groups: (0.1ppm, 1ppm, 10ppm and 100ppm), while the Control group received only normal saline. The gross examination of chicks revealed no abnormality. No pathological changes were detected in microscopical examination of the liver, kidney, spleen, heart, bursa of Fabricius and central nervous system tissues. Blood serum biochemical indices showed no significant differences between control and treatment groups. Interestingly, polyrhodanine nanoparticles showed strong antiviral activity against NDV in ovo. These preliminary findings suggest that polyrhodanine nanoparticles without any toxicity effect could be utilized in controlling Newcastle disease in chickens. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

NASA Astrophysics Data System (ADS)

Li, Chunfang; Li, Dongxiang; Wan, Gangqiang; Xu, Jie; Hou, Wanguo

2011-07-01

The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

Nanoparticle Superlattice Engineering with DNA

NASA Astrophysics Data System (ADS)

Macfarlane, Robert John

In this thesis, we describe a set of design rules for using programmable oligonucleotide interactions, elements of both thermodynamic and kinetic control, and an understanding of the dominant forces that are responsible for particle assembly to design and deliberately make a wide variety of nanoparticle-based superlattices. Like the rules for ionic solids developed by Linus Pauling, these rules are guidelines for determining relative nanoparticle superlattice stability, rather than rigorous mathematical descriptions. However, unlike Pauling's rules, the set of rules developed herein allow one to not just predict crystal stability, but also to deliberately and independently control the nanoparticle sizes, interparticle spacings, and crystallographic symmetries of a superlattice. In the first chapter of this thesis, a general background is given for using DNA as a tool in programmable materials synthesis. Chapter 2 demonstrates how altering oligonucleotide length and nanoparticle size can be used to control nanoparticle superlattice lattice parameters with nanometer-scale precision. In the third chapter, the kinetics of crystallization are examined, and a method to selectively stabilize kinetic products is presented. The data in chapter 4 prove that it is the overall hydrodynamic radius of a DNA-functionalized particle, rather than the sizes of the inorganic nanoparticles being assembled, that dictates particle packing behavior. Chapter 5 demonstrates how particles that exhibit non-equivalent packing behavior can be used to control superlattice symmetry, and chapter 6 utilizes these data to develop a phase diagram that predicts lattice stability a priori to synthesis. In chapter 7, the ability to functionalize a particle with multiple types of oligonucleotides is used to synthesize complex lattices, including ternary superlattices that are capable of dynamic symmetry conversion between a binary and a ternary state. The final chapter provides an outlook on other developments in DNA-programmed nanoparticle assembly not covered in this thesis, as well as future challenges for this field. Supplementary information to support the conclusions of the thesis, as well as provide technical details on how these materials are synthesized, are provided in appendices at the end of the thesis. As a whole, this methodology presents a major advance towards nanoparticle superlattice engineering, as it effectively separates the identity of a particle core (and thereby its physical properties) from the variables that control its assembly, enabling the synthesis of designer nanoparticle-based materials.

Development and evaluation of a novel topical treatment for acne with azelaic acid-loaded nanoparticles.

PubMed

Reis, Catarina Pinto; Gomes, Ana; Rijo, Patrícia; Candeias, Sara; Pinto, Pedro; Baptista, Marina; Martinho, Nuno; Ascensão, Lia

2013-10-01

Azelaic acid (AzA) is used in the treatment of acne. However, side effects and low compliance have been associated with several topical treatments with AzA. Nanotechnology presents a strategy that can overcome these problems. Polymeric nanoparticles can control drug release and targeting and reduce local drug toxicity. The aim of this study was to produce and evaluate an innovative topical treatment for acne with AzA-loaded poly-DL-lactide/glycolide copolymer nanoparticles. A soft white powder of nanoparticles was prepared. The mean size of loaded nanoparticles was < 400 nm and zeta potential was negative. Spherical nanoparticles were observed by scanning electron microscopy. Encapsulation efficiency was around 80% and a strong interaction between the polymer and the drug was confirmed by differential scanning calorimetric analysis. In vitro drug release studies suggested a controlled and pulsatile release profile. System efficacy tests suggested similar results between the loaded nanoparticles and the nonencapsulated drug against the most common bacteria associated with acne. Cytotoxicity of AzA-loaded nanoparticles was concentration dependent, although not pronounced. The occluded patch test seemed to indicate that the formulation excipients were safe and thus AzA-loaded nanoparticles appear to be an efficient and safe treatment for acne.

Shuttling single metal atom into and out of a metal nanoparticle.

PubMed

Wang, Shuxin; Abroshan, Hadi; Liu, Chong; Luo, Tian-Yi; Zhu, Manzhou; Kim, Hyung J; Rosi, Nathaniel L; Jin, Rongchao

2017-10-10

It has long been a challenge to dope metal nanoparticles with a specific number of heterometal atoms at specific positions. This becomes even more challenging if the heterometal belongs to the same group as the host metal because of the high tendency of forming a distribution of alloy nanoparticles with different numbers of dopants due to the similarities of metals in outmost electron configuration. Herein we report a new strategy for shuttling a single Ag or Cu atom into a centrally hollow, rod-shaped Au 24 nanoparticle, forming AgAu 24 and CuAu 24 nanoparticles in a highly controllable manner. Through a combined approach of experiment and theory, we explain the shuttling pathways of single dopants into and out of the nanoparticles. This study shows that the single dopant is shuttled into the hollow Au 24 nanoparticle either through the apex or side entry, while shuttling a metal atom out of the Au 25 to form the Au 24 nanoparticle occurs mainly through the side entry.Doping a metal nanocluster with heteroatoms dramatically changes its properties, but it remains difficult to dope with single-atom control. Here, the authors devise a strategy to dope single atoms of Ag or Cu into hollow Au nanoclusters, creating precise alloy nanoparticles atom-by-atom.

Towards well-defined gold nanomaterials via diafiltration and aptamer mediated synthesis

NASA Astrophysics Data System (ADS)

Sweeney, Scott Francis

Gold nanoparticles have garnered recent attention due to their intriguing size- and shape-dependent properties. Routine access to well-defined gold nanoparticle samples in terms of core diameter, shape, peripheral functionality and purity is required in order to carry out fundamental studies of their properties and to utilize these properties in future applications. For this reason, the development of methods for preparing well-defined gold nanoparticle samples remains an area of active research in materials science. In this dissertation, two methods, diafiltration and aptamer mediated synthesis, are explored as possible routes towards well-defined gold nanoparticle samples. It is shown that diafiltration has considerable potential for the efficient and convenient purification and size separation of water-soluble nanoparticles. The suitability of diafiltration for (i) the purification of water-soluble gold nanoparticles, (ii) the separation of a bimodal distribution of nanoparticles into fractions, (iii) the fractionation of a polydisperse sample and (iv) the isolation of [rimers from monomers and aggregates is studied. NMR, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) measurements demonstrate that diafiltration produces highly pure nanoparticles. UV-visible spectroscopic and transmission electron microscopic analyses show that diafiltration offers the ability to separate nanoparticles of disparate core size, including linked nanoparticles. These results demonstrate the applicability of diafiltration for the rapid and green preparation of high-purity gold nanoparticle samples and the size separation of heterogeneous nanoparticle samples. In the second half of the dissertation, the identification of materials specific aptamers and their use to synthesize shaped gold nanoparticles is explored. The use of in vitro selection for identifying materials specific peptide and oligonucleotide aptamers is reviewed, outlining the specific requirements of in vitro selection for materials and the ways in which the field can be advanced. A promising new technique, in vitro selection on surfaces (ISOS), is developed and the discovery using ISOS of RNA aptamers that bind to evaporated gold is discussed. Analysis of the isolated gold binding RNA aptamers indicates that they are highly structured with single-stranded polyadenosine binding motifs. These aptamers, and similarly isolated peptide aptamers, are briefly explored for their ability to synthesize gold nanoparticles. This dissertation contains both previously published and unpublished co-authored material.

Size-Selected Ag Nanoparticles with Five-Fold Symmetry

PubMed Central

2009-01-01

Silver nanoparticles were synthesized using the inert gas aggregation technique. We found the optimal experimental conditions to synthesize nanoparticles at different sizes: 1.3 ± 0.2, 1.7 ± 0.3, 2.5 ± 0.4, 3.7 ± 0.4, 4.5 ± 0.9, and 5.5 ± 0.3 nm. We were able to investigate the dependence of the size of the nanoparticles on the synthesis parameters. Our data suggest that the aggregation of clusters (dimers, trimer, etc.) into the active zone of the nanocluster source is the predominant physical mechanism for the formation of the nanoparticles. Our experiments were carried out in conditions that kept the density of nanoparticles low, and the formation of larges nanoparticles by coalescence processes was avoided. In order to preserve the structural and morphological properties, the impact energy of the clusters landing into the substrate was controlled, such that the acceleration energy of the nanoparticles was around 0.1 eV/atom, assuring a soft landing deposition. High-resolution transmission electron microscopy images showed that the nanoparticles were icosahedral in shape, preferentially oriented with a five-fold axis perpendicular to the substrate surface. Our results show that the synthesis by inert gas aggregation technique is a very promising alternative to produce metal nanoparticles when the control of both size and shape are critical for the development of practical applications. PMID:20596397

Size-selected ag nanoparticles with five-fold symmetry.

PubMed

Gracia-Pinilla, Miguelángel; Ferrer, Domingo; Mejía-Rosales, Sergio; Pérez-Tijerina, Eduardo

2009-05-15

Silver nanoparticles were synthesized using the inert gas aggregation technique. We found the optimal experimental conditions to synthesize nanoparticles at different sizes: 1.3 ± 0.2, 1.7 ± 0.3, 2.5 ± 0.4, 3.7 ± 0.4, 4.5 ± 0.9, and 5.5 ± 0.3 nm. We were able to investigate the dependence of the size of the nanoparticles on the synthesis parameters. Our data suggest that the aggregation of clusters (dimers, trimer, etc.) into the active zone of the nanocluster source is the predominant physical mechanism for the formation of the nanoparticles. Our experiments were carried out in conditions that kept the density of nanoparticles low, and the formation of larges nanoparticles by coalescence processes was avoided. In order to preserve the structural and morphological properties, the impact energy of the clusters landing into the substrate was controlled, such that the acceleration energy of the nanoparticles was around 0.1 eV/atom, assuring a soft landing deposition. High-resolution transmission electron microscopy images showed that the nanoparticles were icosahedral in shape, preferentially oriented with a five-fold axis perpendicular to the substrate surface. Our results show that the synthesis by inert gas aggregation technique is a very promising alternative to produce metal nanoparticles when the control of both size and shape are critical for the development of practical applications.

Safety and efficacy of antioxidants-loaded nanoparticles for an anti-aging application.

PubMed

Felippi, Cândice C; Oliveira, Dileusa; Ströher, Alessandra; Carvalho, Anderson R; Van Etten, Eliana A M Aquino; Bruschi, Márcia; Raffin, Renata P

2012-04-01

The aim of this work was to perform a pilot study on the safety and efficacy of nanoparticle formulation for cosmetic application. The encapsulated actives in the nanoparticles were a blend of coenzyme Q10, retinyl palmitate, tocopheryl acetate, grape seed oil and linseed oil. The nanoparticle suspension was characterized in terms of pH and particle size. For the safety assessment, alternative methods as cytotoxicity and HET CAM were used. The clinical skin compatibility tests were also performed. The efficacy was evaluated in healthy volunteers presenting different degrees of periorbital wrinkles. Skin hydration was performed by corneometry. The nanoparticles presented narrow size around 140 nm and pH close to neutral and were suitable to cutaneous application. The alternative tests demonstrated that the nanoparticles did not present potential to induce skin irritant effects, cytotoxicity or generate oxidative stress. The clinical assays confirmed the in vitro results, demonstrating the safety of the nanoparticles, which were not irritant, sensitizing and comedogenic. Furthermore, the exposure to UVA light did not cause photoxicity. Regarding the efficacy, nanoparticles presented significant reduction in wrinkle degree after 21 days of application compared to the control. The volunteers could differentiate the nanoparticles and the control product by means of subjective analyses. In conclusion, the nanoparticles containing antioxidant actives were safe for topical use and presented anti-aging activity in vivo and are suitable to be used as cosmetic ingredient.

Influence of ZrO2, SiO2, Al2O3 and TiO2 nanoparticles on maize seed germination under different growth conditions.

PubMed

Karunakaran, Gopalu; Suriyaprabha, Rangaraj; Rajendran, Venkatachalam; Kannan, Narayanasamy

2016-08-01

The focus of this investigation is to evaluate the phytotoxicity of selected metal oxide nanoparticles and microparticles as a function of maize seed germination and root elongation under different growth conditions (Petri plate, cotton and soil). The results of seed germination and root elongation experiments reveal that all the growth conditions show almost similar results. Alumina (Al2O3) and titania (TiO2) nanoparticles significantly reduce the germination percentage, whereas silica (SiO2) nanoparticles and microparticles enhance the same. The results of nanoparticles and microparticles of zirconia (ZrO2) are found to be same as those of controls. Root elongation is enhanced by SiO2 nanoparticles and microparticles treatment, whereas inhibition is observed with Al2O3 and TiO2 nanoparticles and microparticles. The X-ray fluorescence spectrometry data of the treated and control seed samples show that seeds uptake SiO2 particles to a greater extent followed by TiO2, Al2O3 and ZrO2. In addition, the uptake of nanoparticles is found to be greater than that of microparticles. Thus, the tested metal oxides penetrated seeds at the nanoscale as compared with the microscale. This study clarifies phytotoxicity of nanoparticles treated in different growth substrates and highlights the impact of nanoparticles on environment and agricultural systems.

Novel ionically crosslinked casein nanoparticles for flutamide delivery: formulation, characterization, and in vivo pharmacokinetics

PubMed Central

Elzoghby, Ahmed O; Helmy, Maged W; Samy, Wael M; Elgindy, Nazik A

2013-01-01

A novel particulate delivery matrix based on ionically crosslinked casein (CAS) nanoparticles was developed for controlled release of the poorly soluble anticancer drug flutamide (FLT). Nanoparticles were fabricated via oil-in-water emulsification then stabilized by ionic crosslinking of the positively charged CAS molecules below their isoelectric point, with the polyanionic crosslinker sodium tripolyphosphate. With the optimal preparation conditions, the drug loading and incorporation efficiency achieved were 8.73% and 64.55%, respectively. The nanoparticles exhibited a spherical shape with a size below 100 nm and a positive zeta potential (+7.54 to +17.3 mV). FLT was molecularly dispersed inside the nanoparticle protein matrix, as revealed by thermal analysis. The biodegradability of CAS nanoparticles in trypsin solution could be easily modulated by varying the sodium tripolyphosphate crosslinking density. A sustained release of FLT from CAS nanoparticles for up to 4 days was observed, depending on the crosslinking density. After intravenous administration of FLT-CAS nanoparticles into rats, CAS nanoparticles exhibited a longer circulation time and a markedly delayed blood clearance of FLT, with the half-life of FLT extended from 0.88 hours to 14.64 hours, compared with drug cosolvent. The results offer a promising method for tailoring biodegradable, drug-loaded CAS nanoparticles as controlled, long-circulating drug delivery systems of hydrophobic anticancer drugs in aqueous vehicles. PMID:23658490

Phase- and shape-controlled hydrothermal synthesis of CdS nanoparticles, and oriented attachment growth of its hierarchical architectures

NASA Astrophysics Data System (ADS)

Cao, Yali; Hu, Pengfei; Jia, Dianzeng

2013-01-01

Hydrothermal strategies were successfully used to control the phases and morphologies of CdS nanocrystals. In the absence of an external direction-controlling process, the hexagonal and cubic phase well-defined leaf- and flower-like CdS nanocrystals were controlled obtained via adjusting the reaction duration or the concentration of surfactant. Oriented attachment growth modes were suggested for the formation of CdS superstructures, which was clarified through the tracing of temporal evolution of CdS nanoparticles. The CdS superstructures were structured by primary building nanoparticles, and held excellent visible emission with a peak in the green regions. This strategy is very helpful for studying the phase and morphology controlled fabrication of sulfides nanocrystals.

Platinum nanoparticles on gallium nitride surfaces: effect of semiconductor doping on nanoparticle reactivity.

PubMed

Schäfer, Susanne; Wyrzgol, Sonja A; Caterino, Roberta; Jentys, Andreas; Schoell, Sebastian J; Hävecker, Michael; Knop-Gericke, Axel; Lercher, Johannes A; Sharp, Ian D; Stutzmann, Martin

2012-08-01

Platinum nanoparticles supported on n- and p-type gallium nitride (GaN) are investigated as novel hybrid systems for the electronic control of catalytic activity via electronic interactions with the semiconductor support. In situ oxidation and reduction were studied with high pressure photoemission spectroscopy. The experiments revealed that the underlying wide-band-gap semiconductor has a large influence on the chemical composition and oxygen affinity of supported nanoparticles under X-ray irradiation. For as-deposited Pt cuboctahedra supported on n-type GaN, a higher fraction of oxidized surface atoms was observed compared to cuboctahedral particles supported on p-type GaN. Under an oxygen atmosphere, immediate oxidation was recorded for nanoparticles on n-type GaN, whereas little oxidation was observed for nanoparticles on p-type GaN. Together, these results indicate that changes in the Pt chemical state under X-ray irradiation depend on the type of GaN doping. The strong interaction between the nanoparticles and the support is consistent with charge transfer of X-ray photogenerated free carriers at the semiconductor-nanoparticle interface and suggests that GaN is a promising wide-band-gap support material for photocatalysis and electronic control of catalysis.

Solid phase monofunctionalization of gold nanoparticles using ionic exchange resin as polymer support.

PubMed

Zou, Jianhua; Dai, Qiu; Wang, Jinhai; Liu, Xiong; Huo, Qun

2007-07-01

A solid phase modification method using anionic exchange resin as polymer support was developed for the synthesis of monofunctional gold nanoparticles. Based on a "catch and release" mechanism to control the number of functional groups attached to the nanoparticle surface, bifunctional thiol ligands with a carboxylic acid end group were first immobilized at a controlled density on anionic exchange resin through electrostatic interactions. Gold nanoparticles were then immobilized to the anionic exchange resin by a one-to-one place exchange reaction between resin-bound thiol ligands and butanethiol-protected gold nanoparticles in solution. After cleaving off from the resin under mild conditions, gold nanoparticles with a single carboxyl group attached to the surface were obtained as the major product. Experimental conditions such as the solvents used for ligand loading and solid phase place exchange reaction, and the loading density of the ligands, were found to play a critical role towards the successful synthesis of monofunctional nanoparticles. Overall, the noncovalent bond-based ligand immobilization technique reported here greatly simplified the process of solid phase monofunctionalization of nanoparticles compared to a previously reported covalent bond-based ligand immobilization technique.

Synthesis and characterization of polymer-coated manganese ferrite nanoparticles as controlled drug delivery

NASA Astrophysics Data System (ADS)

Wang, Guangshuo; Zhao, Dexing; Ma, Yingying; Zhang, Zhixiao; Che, Hongwei; Mu, Jingbo; Zhang, Xiaoliang; Zhang, Zheng

2018-01-01

In this study, monodisperse and superparamagnetic manganese ferrite (MnFe2O4) nanoparticles have been synthesized by a one-pot sonochemical method using polyvinylpyrrolidone (PVP) as stabilizer. The as-prepared MnFe2O4 nanoparticles were investigated systematically by TEM, XRD, FTIR, XPS, SQUID and MTT. The TEM observation showed that the PVP-coated MnFe2O4 nanoparticles had uniform dispersion with narrow particle size distribution. The magnetization curves demonstrated superparamagnetic properties of the coated MnFe2O4 nanoparticles with good hydrophilicity at room temperature. The in vitro cytotoxicity experiments exhibited negligible cytotoxicity of the obtained PVP-coated MnFe2O4 nanoparticles even at the high concentration of 150 μg/mL after 24 h treatment. More importantly, anti-cancer model drug of doxorubicin hydrochloride (DOX) was loaded on the surface of MnFe2O4 nanoparticles. The drug loading capacity of the developed nanocarrier reached 0.45 mg/mg and the loaded DOX exhibited interesting pH-dependent release behavior. In conclusion, the as-prepared PVP-coated MnFe2O4 nanoparticles were proposed as a potential candidate for controlled drug delivery.