Preparation and anticoagulant activity of N-succinyl chitosan sulfates.

PubMed

Wang, Tan; Zhou, Yue; Xie, Weiguo; Chen, Lingyun; Zheng, Hua; Fan, Lihong

2012-12-01

In order to develop a promising substitute for heparin, N-succinyl chitosan (NSC) was chemically modified by sulfating agent N(SO(3)Na)(3), which were synthesized with sodium bisulfite and sodium nitrite in aqueous solution. The N-succinyl chitosan sulfates (NSCS) products were characterized by infrared spectroscopy (FT-IR) and (13)C NMR. The degree of substitution (DS) of NSCS depended on the ratio of sulfating agent to N-succinyl chitosan, reaction temperature, reaction time and pH of sulfation agent. N-succinyl chitosan sulfates with DS of 1.97 were obtained under optimal conditions. The in vitro coagulation assay of NSCS was determined by activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) assays. The results showed that NSCS obviously prolonged APTT. The anticoagulant activity strongly depended on DS, molecular weight (M(w)) and concentration of NSCS. The anticoagulant activity of NSCS promoted with the increase of DS and concentration, and NSCS exhibited the best anticoagulant activity with the M(w) of 1.37×10(4). Copyright © 2012. Published by Elsevier B.V.

N-(furfural) chitosan hydrogels based on Diels-Alder cycloadditions and application as microspheres for controlled drug release.

PubMed

Montiel-Herrera, Marcelino; Gandini, Alessandro; Goycoolea, Francisco M; Jacobsen, Neil E; Lizardi-Mendoza, Jaime; Recillas-Mota, Maricarmen; Argüelles-Monal, Waldo M

2015-09-05

In this study, chitosan was chemically modified by reductive amination in a two-step process. The synthesis of N-(furfural) chitosan (FC) was confirmed by FT-IR and (1)H NMR analysis, and the degrees of substitution were estimated as 8.3 and 23.8%. The cross-linkable system of bismaleimide (BM) and FC shows that FC shared properties of furan-maleimide chemistry. This system produced non-reversible hydrogel networks by Diels-Alder cycloadditions at 85 °C. The system composed of BM and FC (23.8% substitution) generated stronger hydrogel networks than those of FC with an 8.3% degree of substitution. Moreover, the FC-BM system was able to produce hydrogel microspheres. Environmental scanning electron microscopy revealed the surface of the microspheres to be non-porous with small protuberances. In water, the microspheres swelled, increasing their volume by 30%. Finally, microspheres loaded with methylene blue were able to release the dye gradually, obeying second-order kinetics for times less than 600 min. This behavior suggests that diffusion is governed by the relaxation of polymer chains in the swelled state, thus facilitating drug release outside the microspheres. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mesoporous-activated carbon prepared from chitosan flakes via single-step sodium hydroxide activation for the adsorption of methylene blue.

PubMed

Marrakchi, F; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

2017-05-01

In this work, mesoporous-activated carbon (CSAC) was prepared from chitosan flakes (CS) via single-step sodium hydroxide activation for the adsorption of methylene blue (MB). CSAC was prepared using different impregnation ratios of NaOH:CS (1:1, 2:1, 3:1, and 4:1) at 800°C for 90min. The adsorption performance of CSAC was evaluated for MB at different adsorption variables, such MB initial concentrations (25-400mg/L), solution pH (3-11), and temperature (30-50°C). The adsorption isotherm data of CSAC-MB were well fitted to Langmuir model with a maximum adsorption capacity 143.53mg/g at 50°C. Best representation of kinetic data was obtained by the pseudo-second order model. CSAC exhibited excellent adsorption uptake for MB and can potentially be used for other cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Removal of anionic and cationic dyes with bioadsorbent oxidized chitosans.

PubMed

León, Orietta; Muñoz-Bonilla, Alexandra; Soto, Diana; Pérez, Daniela; Rangel, Medarda; Colina, Marinela; Fernández-García, Marta

2018-08-15

Different oxidized chitosans were prepared following various approaches, by thermo-acid oxidation or by using KMnO 4 /NaHSO 3 , (NH 4 ) 2 S 2 O 8 /NaHSO 3 and K 2 Cr 2 O 7 /NaHSO 3 redox pairs added sequentially or simultaneously. All these reactions pursue the formation of carboxylic groups which enhance their capability to remove model cationic and anionic dyes such as methylene blue and methyl orange, respectively. The resulting oxidized chitosans were structurally and thermally characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy and thermogravimetry. The swelling capacity of these hydrogels was also determined as well as the remediation ability of dyes in different conditions. The results showed that the adsorption of methylene blue followed a pseudo second-order kinetics model, while the adsorption behavior was in agreement with the Langmuir isotherm model. Remarkably, the oxidized chitosans showed removal ability for both dyes cationic and anionic, which of great importance for application of these materials as versatile bioadsorbents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fluoride-Mediated Dephosphonylation of α-Diazo-β-carbonyl Phosphonates.

PubMed

Phatake, Ravindra S; Mullapudi, Venkannababu; Wakchaure, Vivek C; Ramana, Chepuri V

2017-01-20

The possibility of fluoride-mediated selective dephosphonylation of α-diazo-β-carbonyl phosphonates such as the Ohira-Bestmann reagent has been proposed and executed. The resulting α-diazocarbonyl intermediates undergo a (3 + 2)-cycloaddition at room temperature with conjugated olefins and benzynes. Interestingly, under the current conditions, the resulting cycloaddition products underwent either N-acylation (with excess α-diazo-β-carbonyl phosphonates) or Michael addition (with conjugated olefins).

First prize: Chitosan and the urothelial barrier: effects on ureteral intraluminal drug penetration and peristalsis.

PubMed

Pick, Donald L; Shelkovnikov, Stanislav; Canvasser, Noah; Louie, Michael K; Tongson-Ignacio, Jane; McDougall, Elspeth M; Clayman, Ralph V

2011-03-01

Relaxing the ureter prior to endourologic procedures could ease instrument access. In an ex-vivo model, intraluminal nifedipine has been shown to relax the ureter. Chitosan is the deacetylation product of chitin and can alter bladder urothelium. This study examines the effect of nifedipine on peristalsis before and after pretreating the ureter with chitosan. Intact 4-cm tubular porcine ureteral segments were placed in a novel organ bath. To induce peristalsis, phenylephrine (10 μM) was added. Chitosan (0.5% [w/v], 30 minutes) or Krebs (control) was then used to treat the urothelium. The rate and amplitude of ureteral peristalsis was then measured. Intraluminal nifedipine (1 μM) was then added to the intraluminal reservoir. Peristaltic rate and amplitude and the time to aperistalsis were measured. Methylene blue was then added after treatment with chitosan or control to measure diffusion. After Krebs pretreatment, intraluminal nifedipine (1 μM) significantly reduced peristaltic frequency (p = 0.0184) but did not stop peristalsis after 60 minutes of exposure in six trials. After chitosan, nifedipine (1 μM) stopped ureteral peristalsis within an average of 12.30 ± 4.72 minutes. Chitosan alone did not cause aperistalsis. Intraluminal methylene blue did not diffuse into the extraluminal bath after saline or chitosan pretreatment. Histological analysis of the ureter before and after pretreatment with chitosan showed no urothelial disruption. By pretreating the intraluminal surface of the ureter with chitosan, nifedipine blocks ureteral peristalsis at low concentrations. Chitosan changes ureteral urothelial permeability without barrier disruption and has no observed effect on ureteral contraction.

Adsorbed States of phosphonate derivatives of N-heterocyclic aromatic compounds, imidazole, thiazole, and pyridine on colloidal silver: comparison with a silver electrode.

PubMed

Podstawka, Edyta; Olszewski, Tomasz K; Boduszek, Bogdan; Proniewicz, Leonard M

2009-09-03

Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of phosphonate derivatives of the N-heterocyclic aromatic compounds imidazole (ImMeP ([hydroxy(1H-imidazol-5-yl)methyl]phosphonic acid) and (ImMe)(2)P (bis[hydroxy-(1H-imidazol-4-yl)-methyl]phosphinic acid)), thiazole (BAThMeP (butylaminothiazol-2-yl-methyl)phosphonic acid) and BzAThMeP (benzylaminothiazol-2-yl-methyl)phosphonic acid)), and pyridine ((PyMe)(2)P (bis[(hydroxypyridin-3-yl-methyl)]phosphinic acid)) adsorbed on nanometer-sized colloidal particles. We compared these structures to those on a roughened silver electrode surface to determine the relationship between the adsorption strength and the geometry. For example, we showed that all of these biomolecules interact with the colloidal surface through aromatic rings. However, for BzAThMeP, a preferential interaction between the benzene ring and the colloidal silver surface is observed more so than that between the thiazole ring and this substrate. The PC(OH)C fragment does not take part in the adsorption process, and the phosphonate moiety of ImMeP and (ImMe)(2)P, being removed from the surface, only assists in this process.

N-Acetonitrile Functionalized Nitropyrazoles: Precursors to Insensitive Asymmetric N-Methylene-C Linked Azoles.

PubMed

Kumar, Dheeraj; Imler, Gregory H; Parrish, Damon A; Shreeve, Jean'ne M

2017-06-12

Properties of energetic compounds obtained by linking energetic pyrazoles to tetrazoles by means of N-methylene-C bridges can be fine-tuned. Reactions of pyrazole derivatives with chloroacetonitrile followed by conversion of the cyano group to tetrazole using click reactions in the presence of zinc chloride result in asymmetric N-methylene-C bridged azole-based energetic compounds. All the compounds were thoroughly characterized by IR and NMR [ 1 H, 13 C { 1 H}, 15 N] spectroscopy, elemental analysis, and differential scanning calorimetry (DSC), and for two compounds, further supported by single-crystal X-ray diffraction studies. Heats of formation and detonation performances were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively. Initial studies show that this new approach is promising for synthesizing less sensitive energetic compounds with fine-tuned properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-step synthesis of styryl phosphonic acids via palladium-catalyzed Heck coupling of vinyl phosphonic acid with aryl halides

DOE PAGES

McNichols, Brett W.; Koubek, Joshua T.; Sellinger, Alan

2017-10-27

Here, we have developed a single step palladium-catalyzed Heck coupling of aryl halides with vinyl phosphonic acid to produce functionalized (E)-styryl phosphonic acids. This pathway utilizes a variety of commercially available aryl halides, vinyl phosphonic acid and Pd(P(tBu) 3) 2 as catalyst. These conditions produce a wide range of styryl phosphonic acids with high purities and good to excellent yields (31–80%).

Single-step synthesis of styryl phosphonic acids via palladium-catalyzed Heck coupling of vinyl phosphonic acid with aryl halides

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

McNichols, Brett W.; Koubek, Joshua T.; Sellinger, Alan

Here, we have developed a single step palladium-catalyzed Heck coupling of aryl halides with vinyl phosphonic acid to produce functionalized (E)-styryl phosphonic acids. This pathway utilizes a variety of commercially available aryl halides, vinyl phosphonic acid and Pd(P(tBu) 3) 2 as catalyst. These conditions produce a wide range of styryl phosphonic acids with high purities and good to excellent yields (31–80%).

Synthesis and characterization of methyl pyrazolone functionalized magnetic chitosan composite for visible light photocatalytic degradation of methylene blue.

PubMed

Abdelwahab, N A; Morsy, E M H

2018-03-01

TiO 2 /Fe 3 O 4 , TiO 2 /Fe 3 O 4 /chitosan and Methylpyrazolone functionalized TiO 2 /Fe 3 O 4 /chitosan (MPyTMChi) were successfully prepared. The chemical structure of the prepared materials was confirmed by FT-IR spectra, XRD, SEM and TEM. BET surface area increased from 2.4 to 3.1m 2 /g, E g decreased from 2.58 to 2.25eV and more quenching of PL emission spectra was observed upon functionalization of TMChi by MPy. Moreover, high Ti and oxygen percentages were detected by EDX. Magnetization value (M s ) reached 21 emu.g -1 for MPyTMChi. MPyTMChi showed enhanced photocatalytic degradation rate of methylene blue (MB) dye under visibe light irradiation (99.8% after 40min) as compared with that for TiO 2 /Fe 3 O 4 (96.7% after 100min) and TMChi (98.9% after 60min), respectively. It was regarded that the photocatalytic degradation of MB dye on MPyTMChi follows apparent pseudo-first-order according to the Langmuir-Hinshelwood (L-H) model and k app value was 0.089min -1 . Active species trapping experiment revealed that h + and O 2 - played the main role in the photodegradation of MB dye while OH quenching did not greatly affect photodegradation rate. Additionally, MPyTMChi can be efficiently reused for six repetitive cycles. MPyTMChi showed higher antimicrobial activity against gram-positive, gram- negative bacterial and fungal strains while large inhibition zone was observed for gram-positive bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

Structure-activity relationship of (N)-Methanocarba phosphonate analogues of 5'-AMP as cardioprotective agents acting through a cardiac P2X receptor.

PubMed

Kumar, T Santhosh; Zhou, Si-Yuan; Joshi, Bhalchandra V; Balasubramanian, Ramachandran; Yang, Tiehong; Liang, Bruce T; Jacobson, Kenneth A

2010-03-25

P2X receptor activation protects in heart failure models. MRS2339 3, a 2-chloro-AMP derivative containing a (N)-methanocarba (bicyclo[3.1.0]hexane) system, activates this cardioprotective channel. Michaelis-Arbuzov and Wittig reactions provided phosphonate analogues of 3, expected to be stable in vivo due to the C-P bond. After chronic administration via a mini-osmotic pump (Alzet), some analogues significantly increased intact heart contractile function in calsequestrin-overexpressing mice (genetic model of heart failure) compared to vehicle-infused mice (all inactive at the vasodilatory P2Y(1) receptor). Two phosphonates, (1'S,2'R,3'S,4'R,5'S)-4'-(6-amino-2-chloropurin-9-yl)-2',3'-(dihydroxy)-1'-(phosphonomethylene)-bicyclo[3.1.0]hexane, 4 (MRS2775), and its homologue 9 (MRS2935), both 5'-saturated, containing a 2-Cl substitution, improved echocardiography-derived fractional shortening (20.25% and 19.26%, respectively, versus 13.78% in controls), while unsaturated 5'-extended phosphonates, all 2-H analogues, and a CH(3)-phosphonate were inactive. Thus, chronic administration of nucleotidase-resistant phosphonates conferred a beneficial effect, likely via cardiac P2X receptor activation. Thus, we have greatly expanded the range of carbocyclic nucleotide analogues that represent potential candidates for the treatment of heart failure.

Gallium(III) chelates of mixed phosphonate-carboxylate triazamacrocyclic ligands relevant to nuclear medicine: Structural, stability and in vivo studies.

PubMed

Prata, Maria I M; André, João P; Kovács, Zoltán; Takács, Anett I; Tircsó, Gyula; Tóth, Imre; Geraldes, Carlos F G C

2017-12-01

Three triaza macrocyclic ligands, H 6 NOTP (1,4,7-triazacyclononane-N,N',N″-trimethylene phosphonic acid), H 4 NO2AP (1,4,7-triazacyclononane-N-methylenephosphonic acid-N',N″-dimethylenecarboxylic acid), and H 5 NOA2P (1,4,7-triazacyclononane-N,N'-bis(methylenephosphonic acid)-N″-methylene carboxylic acid), and their gallium(III) chelates were studied in view of their potential interest as scintigraphic and PET (Positron Emission Tomography) imaging agents. A 1 H, 31 P and 71 Ga multinuclear NMR study gave an insight on the structure, internal dynamics and stability of the chelates in aqueous solution. In particular, the analysis of 71 Ga NMR spectra gave information on the symmetry of the Ga 3+ coordination sphere and the stability of the chelates towards hydrolysis. The 31 P NMR spectra afforded information on the protonation of the non-coordinated oxygen atoms from the pendant phosphonate groups and on the number of species in solution. The 1 H NMR spectra allowed the analysis of the structure and the number of species in solution. 31 P and 1 H NMR titrations combined with potentiometry afforded the measurement of the protonation constants (log K Hi ) and the microscopic protonation scheme of the triaza macrocyclic ligands. The remarkably high thermodynamic stability constant (log K GaL =34.44 (0.04) and stepwise protonation constants of Ga(NOA2P) 2- were determined by potentiometry and 69 Ga and 31 P NMR titrations. Biodistribution and gamma imaging studies have been performed on Wistar rats using the radiolabeled 67 Ga(NO2AP) - and 67 Ga(NOA2P) 2- chelates, having both demonstrated to have renal excretion. The correlation of the molecular properties of the chelates with their pharmacokinetic properties has been analysed. Copyright © 2017 Elsevier Inc. All rights reserved.

In situ chemical functionalization of gallium nitride with phosphonic acid derivatives during etching.

PubMed

Wilkins, Stewart J; Greenough, Michelle; Arellano, Consuelo; Paskova, Tania; Ivanisevic, Albena

2014-03-04

In situ functionalization of polar (c plane) and nonpolar (a plane) gallium nitride (GaN) was performed by adding (3-bromopropyl) phosphonic acid or propyl phosphonic acid to a phosphoric acid etch. The target was to modulate the emission properties and oxide formation of GaN, which was explored through surface characterization with atomic force microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL), inductively coupled plasma-mass spectrometry, and water contact angle. The use of (3-bromopropyl) phosphonic acid and propyl phosphonic acid in phosphoric acid demonstrated lower amounts of gallium oxide formation and greater hydrophobicity for both sample sets, while also improving PL emission of polar GaN samples. In addition to crystal orientation, growth-related factors such as defect density in bulk GaN versus thin GaN films residing on sapphire substrates were investigated as well as their responses to in situ functionalization. Thin nonpolar GaN layers were the most sensitive to etching treatments due in part to higher defect densities (stacking faults and threading dislocations), which accounts for large surface depressions. High-quality GaN (both free-standing bulk polar and bulk nonpolar) demonstrated increased sensitivity to oxide formation. Room-temperature PL stands out as an excellent technique to identify nonradiative recombination as observed in the spectra of heteroepitaxially grown GaN samples. The chemical methods applied to tune optical and physical properties of GaN provide a quantitative framework for future novel chemical and biochemical sensor development.

Hydrothermal syntheses, characterizations and crystal structures of a new lead(II) carboxylate-phosphonate with a double layer structure and a new nickel(II) carboxylate-phosphonate containing a hydrogen-bonded 2D layer with intercalation of ethylenediamines

NASA Astrophysics Data System (ADS)

Song, Jun-Ling; Mao, Jiang-Gao; Sun, Yan-Qiong; Zeng, Hui-Yi; Kremer, Reinhard K.; Clearfield, Abraham

2004-03-01

Hydrothermal reactions of N, N-bis(phosphonomethyl)aminoacetic acid (HO 2CCH 2N(CH 2PO 3H 2) 2) with metal(II) salts afforded two new metal carboxylate-phosphonates, namely, Pb 2[O 2CCH 2N(CH 2PO 3)(CH 2PO 3H)]·H 2O ( 1) and {NH 3CH 2CH 2NH 3}{Ni[O 2CCH 2N(CH 2PO 3H) 2](H 2O) 2} 2 ( 2). Among two unique lead(II) ions in the asymmetric unit of complex 1, one is five coordinated by five phosphonate oxygen atoms from 5 ligands, whereas the other one is five-coordinated by a tridentate chelating ligand (1 N and 2 phosphonate O atoms) and two phosphonate oxygen atoms from two other ligands. The carboxylate group of the ligand remains non-coordinated. The bridging of above two types of lead(II) ions through phosphonate groups resulted in a <002> double layer with the carboxylate group of the ligand as a pendant group. These double layers are further interlinked via hydrogen bonds between the carboxylate groups into a 3D network. The nickel(II) ion in complex 2 is octahedrally coordinated by a tetradentate chelating ligand (two phosphonate oxygen atoms, one nitrogen and one carboxylate oxygen atoms) and two aqua ligands. These {Ni[O 2CCH 2N(CH 2PO 3H) 2][H 2O] 2} - anions are further interlinked via hydrogen bonds between non-coordinated phosphonate oxygen atoms to form a <800> hydrogen bonded 2D layer. The 2H-protonated ethylenediamine cations are intercalated between two layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Results of magnetic measurements for complex 2 indicate that there is weak Curie-Weiss behavior with θ=-4.4 K indicating predominant antiferromagnetic interaction between the Ni(II) ions. Indication for magnetic low-dimension magnetism could not be detected.

Preparation and characterization of N-benzoyl-O-acetyl-chitosan.

PubMed

Cai, Jinping; Dang, Qifeng; Liu, Chengsheng; Fan, Bing; Yan, Jingquan; Xu, Yanyan; Li, Jingjing

2015-01-01

A novel amphipathic chitosan derivative, N-benzoyl-O-acetyl-chitosan (BACS), was prepared by using the selective partial acylation of chitosan (CS), benzoyl chloride, and acetic acid under high-intensity ultrasound. The chemical structure and physical properties of BACS were characterized by FTIR, (1)H NMR, TGA, and XRD techniques. The degrees of substitution of benzoyl and acetyl for the chitosan derivatives were 0.26 and 1.15, respectively, which were calculated from the peak areas in NMR spectra by using the combined integral methods. The foaming properties of CS and BACS were determined and the results suggested BACS had better foam capacity and stability than those of chitosan. In addition, the antimicrobial activities of CS and BACS were also investigated against two species of bacteria (Escherichia coli and Staphylococcus aureus) and a fungus (Aspergillus niger), the results indicated that the antibacterial and antifungal activities of BACS were much stronger than those of the parent chitosan. These findings suggested that BACS was preferable for use as a food additive with a dual role of both foaming agent and food preservative. Copyright © 2015 Elsevier B.V. All rights reserved.

Organophosphonates: A review on environmental relevance, biodegradability and removal in wastewater treatment plants.

PubMed

Rott, Eduard; Steinmetz, Heidrun; Metzger, Jörg W

2018-02-15

The worldwide increasing consumption of the phosphonates 2-phosphonobutane-1,2,4-tricarboxylic acid [PBTC], 1-hydroxyethane 1,1-diphosphonic acid [HEDP], nitrilotris(methylene phosphonic acid) [NTMP], ethylenediamine tetra(methylene phosphonic acid) [EDTMP] and diethylenetriamine penta(methylene phosphonic acid) [DTPMP] over the past decades put phosphonates into focus of environmental scientists and agencies, as they are increasingly discussed in the context of various environmental problems. The hitherto difficult analysis of phosphonates contributed to the fact that very little is known about their concentrations and behavior in the environment. This work critically reviews the existing literature up to the year 2016 on the potential environmental relevance of phosphonates, their biotic and abiotic degradability, and their removal in wastewater treatment plants (WWTPs). Accordingly, despite their stability against biological degradation, phosphonates can be removed with relatively high efficiency (>80%) in WWTPs operated with chemical phosphate precipitation. In the literature, however, to our knowledge, there is no information as to whether an enhanced biological phosphorus removal alone is sufficient for such high removal rates and whether the achievable phosphonate concentrations in effluents are sufficiently low to prevent eutrophication. It is currently expected that phosphonates, although being complexing agents, do not remobilize heavy metals from sediments in a significant amount since the phosphonate concentrations required for this (>50μg/L) are considerably higher than the concentrations determined in surface waters. Various publications also point out that phosphonates are harmless to a variety of aquatic organisms. Moreover, degradation products thereof such as N-(phosphonomethyl)glycine and aminomethylphosphonic acid are regarded as being particularly critical. Despite their high stability against biological degradation, phosphonates contribute to

Discovery of phosphonic acid natural products by mining the genomes of 10,000 actinomycetes.

PubMed

Ju, Kou-San; Gao, Jiangtao; Doroghazi, James R; Wang, Kwo-Kwang A; Thibodeaux, Christopher J; Li, Steven; Metzger, Emily; Fudala, John; Su, Joleen; Zhang, Jun Kai; Lee, Jaeheon; Cioni, Joel P; Evans, Bradley S; Hirota, Ryuichi; Labeda, David P; van der Donk, Wilfred A; Metcalf, William W

2015-09-29

Although natural products have been a particularly rich source of human medicines, activity-based screening results in a very high rate of rediscovery of known molecules. Based on the large number of natural product biosynthetic genes in microbial genomes, many have proposed "genome mining" as an alternative approach for discovery efforts; however, this idea has yet to be performed experimentally on a large scale. Here, we demonstrate the feasibility of large-scale, high-throughput genome mining by screening a collection of over 10,000 actinomycetes for the genetic potential to make phosphonic acids, a class of natural products with diverse and useful bioactivities. Genome sequencing identified a diverse collection of phosphonate biosynthetic gene clusters within 278 strains. These clusters were classified into 64 distinct groups, of which 55 are likely to direct the synthesis of unknown compounds. Characterization of strains within five of these groups resulted in the discovery of a new archetypical pathway for phosphonate biosynthesis, the first (to our knowledge) dedicated pathway for H-phosphinates, and 11 previously undescribed phosphonic acid natural products. Among these compounds are argolaphos, a broad-spectrum antibacterial phosphonopeptide composed of aminomethylphosphonate in peptide linkage to a rare amino acid N(5)-hydroxyarginine; valinophos, an N-acetyl l-Val ester of 2,3-dihydroxypropylphosphonate; and phosphonocystoximate, an unusual thiohydroximate-containing molecule representing a new chemotype of sulfur-containing phosphonate natural products. Analysis of the genome sequences from the remaining strains suggests that the majority of the phosphonate biosynthetic repertoire of Actinobacteria has been captured at the gene level. This dereplicated strain collection now provides a reservoir of numerous, as yet undiscovered, phosphonate natural products.

Discovery of phosphonic acid natural products by mining the genomes of 10,000 actinomycetes

PubMed Central

Ju, Kou-San; Gao, Jiangtao; Doroghazi, James R.; Wang, Kwo-Kwang A.; Thibodeaux, Christopher J.; Li, Steven; Metzger, Emily; Fudala, John; Su, Joleen; Zhang, Jun Kai; Lee, Jaeheon; Cioni, Joel P.; Evans, Bradley S.; Hirota, Ryuichi; Labeda, David P.; van der Donk, Wilfred A.; Metcalf, William W.

2015-01-01

Although natural products have been a particularly rich source of human medicines, activity-based screening results in a very high rate of rediscovery of known molecules. Based on the large number of natural product biosynthetic genes in microbial genomes, many have proposed “genome mining” as an alternative approach for discovery efforts; however, this idea has yet to be performed experimentally on a large scale. Here, we demonstrate the feasibility of large-scale, high-throughput genome mining by screening a collection of over 10,000 actinomycetes for the genetic potential to make phosphonic acids, a class of natural products with diverse and useful bioactivities. Genome sequencing identified a diverse collection of phosphonate biosynthetic gene clusters within 278 strains. These clusters were classified into 64 distinct groups, of which 55 are likely to direct the synthesis of unknown compounds. Characterization of strains within five of these groups resulted in the discovery of a new archetypical pathway for phosphonate biosynthesis, the first (to our knowledge) dedicated pathway for H-phosphinates, and 11 previously undescribed phosphonic acid natural products. Among these compounds are argolaphos, a broad-spectrum antibacterial phosphonopeptide composed of aminomethylphosphonate in peptide linkage to a rare amino acid N5-hydroxyarginine; valinophos, an N-acetyl l-Val ester of 2,3-dihydroxypropylphosphonate; and phosphonocystoximate, an unusual thiohydroximate-containing molecule representing a new chemotype of sulfur-containing phosphonate natural products. Analysis of the genome sequences from the remaining strains suggests that the majority of the phosphonate biosynthetic repertoire of Actinobacteria has been captured at the gene level. This dereplicated strain collection now provides a reservoir of numerous, as yet undiscovered, phosphonate natural products. PMID:26324907

Textile Dye Removal from Aqueous Solution using Modified Graphite Waste/Lanthanum/Chitosan Composite

NASA Astrophysics Data System (ADS)

Kusrini, E.; Wicaksono, B.; Yulizar, Y.; Prasetyanto, EA; Gunawan, C.

2018-03-01

We investigated various pre-treatment processes of graphite waste using thermal, mechanical and chemical methods. The aim of this work is to study the performance of modified graphite waste/lanthanum/chitosan composite (MG) as adsorbent for textile dye removal from aqueous solution. Effect of graphite waste resources, adsorbent size and lanthanum concentration on the dye removal were studied in batch experiments. Selectivity of MG was also investigated. Pre-heated graphite waste (NMG) was conducted at 80°C for 1 h, followed by mechanical crushing of the resultant graphite to 75 μm particle size, giving adsorption performance of ˜58%, ˜67%, ˜93% and ˜98% of the model dye rhodamine B (concentration determined by UV-vis spectroscopy at 554 nm), methyl orange (464 nm), methylene blue (664 nm) and methyl violet (580 nm), respectively from aqueous solution. For this process, the system required less than ˜5 min for adsorbent material to be completely saturated with the adsorbate. Further chemical modification of the pre-treated graphite waste (MG) with lanthanum (0.01 – V 0.03 M) and chitosan (0.5% w/w) did not improve the performance of dye adsorption. Under comparable experimental conditions, as those of the ‘thermal-mechanical-pre-treated-only’ (NMG), modification of graphite waste (MG) with 0.03 M lanthanum and 0.5% w/w chitosan resulted in ˜14%, ˜47%, ˜72% and ˜85% adsorption of rhodamine B, methyl orange, methylene blue and methyl violet, respectively. Selective adsorption of methylene blue at most to ˜79%, followed by methyl orange, methyl violet and rhodamine B with adsorption efficiency ˜67, ˜38, and ˜9% sequentially using MG with 0.03 M lanthanum and 0.5% w/w chitosan.

Lactosaminated- N-succinyl chitosan nanoparticles for hepatocyte-targeted delivery of acyclovir

NASA Astrophysics Data System (ADS)

Jain, Nivrati; Rajoriya, Vaibhav; Jain, Prateek Kumar; Jain, Ashish Kumar

2014-01-01

The present study discusses lactose-acyclovir- N-succinyl chitosan nanoparticles (Lac- N-Suc-CSNP) using lactose as an asialoglycoprotein receptor (ASGPR) ligand for hepatic parenchymatic cells targeting. For this purpose, N-succinyl chitosan nanoparticles ( N-Suc-CSNP) were prepared previously by ionotropic gelation method and lactose was conjugated to the free amino terminal group of chitosan. Lactose conjugation with N-Suc-CSNP was confirmed by FT-IR and zeta potential measurements. The Lac- N-Suc-CSNP obtained were characterized for their morphology, particle size, polydispersity index, and zeta potential. The Lac- N-Suc-CSNP showed spherical in shape with 220.3 ± 5.0 nm size range, +4.1 ± 0.2 mV zeta potential, 62.5 ± 1.2 % acyclovir entrapment efficiency and showed 27.3 ± 0.9 % cumulative acyclovir release up to 72 h. The acyclovir concentration from Lac- N-Suc-CSNP was found to be 19.9 ± 1.62 μg/g after 24 h administration revealed remarkably targeting potential to the hepatocytes and keep at a high level during the experiment. These results suggest that Lac- N-Suc-CSNP are potentially vector for hepatocytes targeting.

Recent advances in H-phosphonate chemistry. Part 1. H-phosphonate esters: synthesis and basic reactions.

PubMed

Sobkowski, Michal; Kraszewski, Adam; Stawinski, Jacek

2015-01-01

This review covers recent progress in the preparation of H-phosphonate mono- and diesters, basic studies on mechanistic and stereochemical aspects of this class of phosphorus compounds, and their fundamental chemistry in terms of transformation of P-H bonds into P-heteroatom bonds. Selected recent applications of H-phosphonate derivatives in basic organic phosphorus chemistry and in the synthesis of biologically important phosphorus compounds are also discussed.

Hierarchical mesostructured titanium phosphonates with unusual uniform lines of macropores.

PubMed

Ma, Tian-Yi; Lin, Xiu-Zhen; Zhang, Xue-Jun; Yuan, Zhong-Yong

2011-04-01

Organic-inorganic hybrid materials of mesostructured titanium phosphonates with unusual uniform lines of macropores were synthesized by using bis(hexamethylenetriamine) penta(methylenephosphonic acid) (BHMTPMP) as the coupling molecule, through a one-pot hydrothermal process without any surfactant assistance. A wormhole-like mesostructure and many uniform parallel lines of macropores divided by solid ridges in the same direction were confirmed by N(2) sorption, SEM and TEM observations. This novel macropore architecture has never been observed in other metal phosphonate materials, which may be directly related to the structure nature of BHMTPMP with extra long alkyl chains. The structural characterization of FT-IR and MAS NMR revealed the integrity of organic groups inside the hybrid framework. The hybrid materials were also used as adsorbents for heavy metal ions and CO(2), in order to clarify the impacts of the organic contents and organic types on the physicochemical properties of the synthesized hierarchical macro-/mesoporous phosphonate materials.

An efficient preparation of isosteric phosphonate analogues of sphingolipids by opening of oxirane and cyclic sulfamidate intermediates with alpha-lithiated alkylphosphonic esters.

PubMed

Sun, Chaode; Bittman, Robert

2004-10-29

D-erythro-(2S,3R,4E)-Sphingosine-1-phosphonate (1), the isosteric phosphonate analogue of naturally occurring sphingosine 1-phosphate (1a), and D-ribo-phytosphingosine 1-phosphonate (2), the isosteric phosphonate analogue of D-ribo-phytosphingosine-1-phosphate (2a), were synthesized starting with methyl 2,3-O-isopropylidene-d-glycerate (4) and D-ribo-phytosphingosine (3), respectively. Oxirane 12 was formed in eight steps from 4, and cyclic sulfamidate 22 was formed in five steps from 3. The phosphonate group was introduced via regioselective ring-opening reactions of oxirane 12 and cyclic sulfamidate 22 with lithium dialkyl methylphosphonate, affording 13 and 23, respectively. The synthesis of 1 was completed by S(N)2 displacement of chloromesylate intermediate 14b with azide ion, followed by conversion of the resulting azido group to a NHBoc group and deprotection. The synthesis of 2 was completed by cleavage of the acetal, N-benzyl, and alkyl phosphonate ester groups.

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

PubMed Central

2016-01-01

Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this paper, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (ϕNpm) values ranging from 0.13 to 0.44 and dispersity (Đ) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Dry samples with ϕNpm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. We demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers. PMID:27134312

40 CFR 721.10677 - Alkyl phosphonate (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10677 Alkyl phosphonate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl phosphonate (PMN P-12-584...

Two isomeric lead(II) carboxylate-phosphonates: syntheses, crystal structures and characterizations

NASA Astrophysics Data System (ADS)

Lei, Chong; Mao, Jiang-Gao; Sun, Yan-Qiong

2004-07-01

Two isomeric layered lead(II) carboxylate-phosphonates of N-(phosphonomethyl)- N-methyl glycine ([MeN(CH 2CO 2H)(CH 2PO 3H 2)]=H 3L), namely, monoclinic Pb 3L 2·H 2O 1 and triclinic Pb 3L 2·H 2O 2, have been synthesized and structurally determined. Compound 1 synthesized by hydrothermal reaction at 150°C is monoclinic, space group C2/ c with a=19.9872(6), b=11.9333(1) and c=15.8399(4) Å, β=110.432(3)°, V=3540.3(1) Å 3, and Z=8. The structure of compound 1 features a <400> layer in which the lead(II) ions are bridged by both phosphonate and carboxylate groups. The lattice water molecules are located between the layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Compound 2 with a same empirical formula as compound 1 was synthesized by hydrothermal reaction at 170°C. It has a different layer structure from that of compound 1 due to the adoption of a different coordination mode for the ligand. It crystallizes in the triclinic system, space group P 1¯ with cell parameters of a=7.1370(6), b=11.522(1), c=11.950(1) Å, α=110.280(2), β=91.625(2), γ=95.614(2)°, V=915.3(1) Å 3 and Z=2. The structure of compound 2 features a <020> metal carboxylate-phosphonate double layer built from 1D lead(II) carboxylate chains interconnected with 1D lead(II) phosphonate double chains. XRD powder patterns of compounds 1 and 2 indicate that each compound exists as a single phase.

Investigation of an elutable N-propylphosphonic acid chitosan derivative composition with a chitosan matrix prepared from carbonic acid solution.

PubMed

Mania, Szymon; Tylingo, Robert; Augustin, Ewa; Gucwa, Katarzyna; Szwacki, Jakub; Staroszczyk, Hanna

2018-01-01

Porous chitosan composites using CO 2 dissolution procedure and including water soluble N-propylphosphonic chitosan derivative (p-CHI) were obtained and characterized. In contrast to the control material, composites containing modified chitosan distinguished by a rapid moisture absorption and good adhesion to the skin. The FTIR analysis confirmed the presence of propylphosphonic group in the structure of the polymer. The porosity of the materials was in the range 55-77% and decreased with increasong amount of modified chitosan in materials. Solubility of composites was dependent on the content of p-CHI in scaffolds (40%, 25% and 15%) and reached values 11%, 9% and 6,5%, respectively. The values of other parameters like swelling degree (30g/g) good antioxidant and antimicrobial properties (almost 100% reduction of S.aureus, E.coli and C. albicans growth) and low in vitro cytotoxicity against fibroblasts were highly advantageous for possible biomedical applications of the composites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structure of the Escherichia coli Phosphonate Binding Protein PhnD and Rationally Optimized Phosphonate Biosensors

PubMed Central

Alicea, Ismael; Marvin, Jonathan S.; Miklos, Aleksandr E.; Ellington, Andrew D.; Looger, Loren L.; Schreiter, Eric R.

2012-01-01

The phnD gene of Escherichia coli encodes the periplasmic binding protein of the phosphonate uptake and utilization pathway. We have crystallized and determined structures of E. coli PhnD (EcPhnD) in the absence of ligand and in complex with the environmentally abundant 2-aminoethylphosphonate (2AEP). Similar to other bacterial periplasmic binding proteins, 2AEP binds near the center of mass of EcPhnD in a cleft formed between two lobes. Comparison of the open, unliganded structure with the closed 2AEP-bound structure shows that the two lobes pivot around a hinge by ~70° between the two states. Extensive hydrogen bonding and electrostatic interactions stabilize 2AEP, which binds to EcPhnD with low nanomolar affinity. These structures provide insight into phosphonate uptake by bacteria and facilitated the rational design of high signal-to-noise phosphonate biosensors based both on coupled small molecule dyes and autocatalytic fluorescent proteins. PMID:22019591

Phosphonate removal from discharged circulating cooling water using iron-carbon micro-electrolysis.

PubMed

Zhou, Zhen; Qiao, Weimin; Lin, Yangbo; Shen, Xuelian; Hu, Dalong; Zhang, Jianqiao; Jiang, Lu-Man; Wang, Luochun

2014-01-01

Phosphonate is a commonly used corrosion and scale inhibitor for a circulating cooling water (CCW) system. Its discharge could cause eutrophication of receiving waters. The iron-carbon (Fe/C) micro-electrolysis technology was used to degrade and remove phosphonate from discharged CCW. The influences of initial pH, Fe/C ratio (FCR) and temperature on phosphonate removal were investigated in a series of batch tests and optimized by response surface methodology. The quadratic model of phosphonate removal was obtained with satisfactory degrees of fitness. The optimum conditions with total phosphorus removal efficiency of 95% were obtained at pH 7.0, FCR of 1.25, and temperature of 45 °C. The phosphonate removal mechanisms were also studied. Phosphonate removal occurred predominantly via two consecutive reactive phases: the degradation of phosphonate complexes (Ca-phosphonate) and the precipitation of Fe/C micro-electrolysis products (PO₄(3-), Ca²⁺ and Fe³⁺).

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

DOE PAGES

Sun, Jing; Jiang, Xi; Siegmund, Aaron; ...

2016-04-04

Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this study, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (Φ Npm) values ranging from 0.13 to 0.44 and dispersity (¯D) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Drymore » samples with Φ Npm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. Finally, we demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers.« less

Syntheses, crystal structures and characterizations of new zinc (II) and lead (II) carboxylate-phosphonates

NASA Astrophysics Data System (ADS)

Song, Jun-Ling; Mao, Jiang-Gao

2005-04-01

The syntheses, crystal structures and characterizations of two new divalent metal carboxylate-phosphonates, namely, Zn(H 3L)·2H 2O ( 1) and Pb(H 3L)(H 2O) 2 ( 2) (H 5L dbnd6 4-HO 2C-C 6H 4-CH 2N(CH 2PO 3H 2) 2) have been reported. Compound 1 features a 1D column structure in which the Zn(II) ions are tetrahedrally coordinated by four phosphonate oxygen atoms from four phosphonate ligands, and neighboring such 1D building blocks are further interconnected via hydrogen bonds into a 3D network. The carboxylate group of H 3L anion remains non-coordinated. Compound 2 has a 2D layer structure. Pb(II) ion is 7-coordinated by four phosphonate oxygen atoms from four phosphonate ligands and three aqua ligands. The interconnection of Pb(II) ions via bridging H 3L anions results in a <001> layer. The carboxylate group of the H 3L anion also remains non-coordinated and is oriented toward the interlayer space. Solid state luminescent spectrum of compound 1 exhibits a strong broad blue fluorescent emission band at 455 nm under excitation at 365 nm at room temperature.

Nanoparticles Prepared From N,N-Dimethyl-N-Octyl Chitosan as the Novel Approach for Oral Delivery of Insulin: Preparation, Statistical Optimization and In-vitro Characterization

PubMed Central

Shamsa, Elnaz Sadat; Mahjub, Reza; Mansoorpour, Maryam; Rafiee-Tehrani, Morteza; Abedin Dorkoosh, Farid

2018-01-01

In this study, N,N-Dimethyl-N-Octyl chitosan was synthesized. Nanoparticles containing insulin were prepared using PEC method and were statistically optimized using the Box-Behnken response surface methodology. The independent factors were considered to be the insulin concentration, concentration and pH of the polymer solution, while the dependent factors were characterized as the size, zeta potential, PdI and entrapment efficiency. The optimized nanoparticles were morphologically studied using SEM. The cytotoxicity of the nanoparticles on the Caco-2 cell culture was studied using the MTT cytotoxicity assay method, while the permeation of the insulin nanoparticles across the Caco-2 cell monolayer was also determined. The optimized nanoparticles posed appropriate physicochemical properties. The SEM morphological studies showed spherical to sub-spherical nanoparticles with no sign of aggregation. The in-vitro release study showed that 95.5 ± 1.40% of the loaded insulin was released in 400 min. The permeability studies revealed significant enhancement in the insulin permeability using nanoparticles prepared from octyl chitosan at 240 min (11.3 ± 0.78%). The obtained data revealed that insulin nanoparticles prepared from N,N-Dimethyl-N-Octyl chitosan can be considered as the good candidate for oral delivery of insulin compared to nanoparticles prepared from N,N,N-trimethyl chitosan.

Chitosan based metallic nanocomposite scaffolds as antimicrobial wound dressings.

PubMed

Mohandas, Annapoorna; Deepthi, S; Biswas, Raja; Jayakumar, R

2018-09-01

Chitosan based nanocomposite scaffolds have attracted wider applications in medicine, in the area of drug delivery, tissue engineering and wound healing. Chitosan matrix incorporated with nanometallic components has immense potential in the area of wound dressings due to its antimicrobial properties. This review focuses on the different combinations of Chitosan metal nanocomposites such as Chitosan/nAg, Chitosan/nAu, Chitosan/nCu, Chitosan/nZnO and Chitosan/nTiO 2 towards enhancement of healing or infection control with special reference to the antimicrobial mechanism of action and toxicity.

Quantitative structure-property relationship (correlation analysis) of phosphonic acid-based chelates in design of MRI contrast agent.

PubMed

Tiwari, Anjani K; Ojha, Himanshu; Kaul, Ankur; Dutta, Anupama; Srivastava, Pooja; Shukla, Gauri; Srivastava, Rakesh; Mishra, Anil K

2009-07-01

Nuclear magnetic resonance imaging is a very useful tool in modern medical diagnostics, especially when gadolinium (III)-based contrast agents are administered to the patient with the aim of increasing the image contrast between normal and diseased tissues. With the use of soft modelling techniques such as quantitative structure-activity relationship/quantitative structure-property relationship after a suitable description of their molecular structure, we have studied a series of phosphonic acid for designing new MRI contrast agent. Quantitative structure-property relationship studies with multiple linear regression analysis were applied to find correlation between different calculated molecular descriptors of the phosphonic acid-based chelating agent and their stability constants. The final quantitative structure-property relationship mathematical models were found as--quantitative structure-property relationship Model for phosphonic acid series (Model 1)--log K(ML) = {5.00243(+/-0.7102)}- MR {0.0263(+/-0.540)}n = 12 l r l = 0.942 s = 0.183 F = 99.165 quantitative structure-property relationship Model for phosphonic acid series (Model 2)--log K(ML) = {5.06280(+/-0.3418)}- MR {0.0252(+/- .198)}n = 12 l r l = 0.956 s = 0.186 F = 99.256.

40 CFR 721.10412 - Phosphonic acid ester (generic) (P-07-706).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphonic acid ester (generic) (P-07... Specific Chemical Substances § 721.10412 Phosphonic acid ester (generic) (P-07-706). (a) Chemical substance... phosphonic acid ester (PMN P-07-706) is subject to reporting under this section for the significant new uses...

40 CFR 721.10412 - Phosphonic acid ester (generic) (P-07-706).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphonic acid ester (generic) (P-07... Specific Chemical Substances § 721.10412 Phosphonic acid ester (generic) (P-07-706). (a) Chemical substance... phosphonic acid ester (PMN P-07-706) is subject to reporting under this section for the significant new uses...

40 CFR 721.10412 - Phosphonic acid ester (generic) (P-07-706).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphonic acid ester (generic) (P-07... Specific Chemical Substances § 721.10412 Phosphonic acid ester (generic) (P-07-706). (a) Chemical substance... phosphonic acid ester (PMN P-07-706) is subject to reporting under this section for the significant new uses...

A direct conversion of benzylic and allylic alcohols to phosphonates

PubMed Central

Barney, Rocky J.; Richardson, Rebekah M.; Wiemer, David F.

2011-01-01

Benzyl phosphonate esters often serve as reagents in Horner-Wadsworth-Emmons reactions. In most cases, they can be prepared from benzylic alcohols via formation of the corresponding halide followed by an Arbuzov reaction. To identify a more direct synthesis of phosphonate esters, we have developed a one-flask procedure for conversion of benzylic and allylic alcohols to the corresponding phosphonates through treatment with triethyl phosphite and ZnI2. PMID:21405073

Nanocomposites of phosphonic-acid-functionalized polyethylenes with inorganic quantum dots.

PubMed

Rünzi, Thomas; Baier, Moritz C; Negele, Carla; Krumova, Marina; Mecking, Stefan

2015-01-01

Insertion of diethyl vinyl phosphonates and free vinyl phosphonic acid, respectively, into [(P^O)Pd(Me)(dmso)] ((P^O) = κ(2)-P,O-Ar2PC6H4SO2O with Ar = 2-MeOC6H4) (1-dmso) occurs in a 2,1- as well as 1,2-fashion, to form a four-and a five-membered chelate [(P^O)Pd{κ(2)-C,O-CH(P(O)(OR)2)CH2CH3}] and [(P^O)Pd{κ(2)-C,O-CH2CH(P(O)(OR)2)CH3}] (R = H, Et). No decomposition or other reactions of 1 by free phosphonic acid moieties occur. Copolymerization in a pressure reactor by 1-dmso yields linear random poly(ethylene-co-diethyl vinyl phosphonate) and poly(ethylene-co-vinyl phosphonic acid). In these copolymerizations, reversible coordination of the phosphonate moieties of free monomer as well as chelate formation by incorporated monomer retards chain growth as also evidenced by relative binding studies of diethyl phosphonate towards 1. Post-polymerization emulsification of poly(ethylene-co-vinyl phosphonic acid) together with CdSe/CdS quantum dots (QDs) yields submicron (ca. 50 nm from dynamic light scattering (DLS) and transmission electron microscopy (TEM)) polymer particles with the QDs embedded in the functionalized polyethylene in a nonaggregated fashion. This embedding benefits the fluorescence behavior in terms of continuous emission and life-time as revealed by wide-field fluorescence measurements. These composite particle dispersions are employed as a ″masterbatch" together with an aqueous high density polyethylene (HDPE) dispersion to generate thin films (by spin-coating) and bulk materials (from the melt), respectively, in which the inorganic nanoparticles remain highly disperse. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The use of cross-linked chitosan beads for nutrients (nitrate and orthophosphate) removal from a mixture of P-PO4, N-NO2 and N-NO3.

PubMed

Jóźwiak, Tomasz; Filipkowska, Urszula; Szymczyk, Paula; Kuczajowska-Zadrożna, Małgorzata; Mielcarek, Artur

2017-11-01

A hydrogel chitosan sorbent ionically cross-linked with sodium citrate and covalently cross-linked with epichlorohydrin was used to remove nutrients from an equimolar mixture of P-PO 4 , N-NO 2 and N-NO 3 . The scope of the study included, among other things, determination of the influence of pH on nutrient sorption effectiveness, nutrient sorption kinetics as well as determination of the maximum sorption capacity of cross-linked chitosan sorbents regarding P-PO 4 (H 2 PO 4 - , HPO 4 2- ), N-NO 2 (HNO 2 , NO 2 - ), and N-NO 3 (NO 3 - ). The effect of the type of the cross-linking agent on the affinity of the modified chitosan to each nutrient was studied as well. The kinetics of nutrient sorption on the tested chitosan sorbents was best described with the pseudo-second order model. The model of intramolecular diffusion showed that P-PO 4 , N-NO 2 and N-NO3 sorption on cross-linked hydrogel chitosan beads proceeded in two phases. The best sorbent of nutrients turned out to be chitosan cross-linked covalently with epichlorohydrin; with P-PO 4 , N-NO 2 and N-NO 3 sorption capacity reaching: 1.23, 0.94 and 0.76mmol/g, respectively (total of 2.92mmol/g). For comparison, the sorption capacity of chitosan cross-linked ionically with sodium citrate was: 0.43, 0.39 and 0.39mmol/g for P-PO 4 , N-NO 2 and N-NO 3 , respectively (total of 1.21mmol/g). Copyright © 2017 Elsevier B.V. All rights reserved.

Diversity and abundance of phosphonate biosynthetic genes in nature

USDA-ARS?s Scientific Manuscript database

Phosphonates, molecules containing direct C-P bonds, comprise a structurally diverse class of natural products with interesting and useful biological properties. Although their synthesis in protozoa was discovered more than fifty years ago, the extent and diversity of phosphonate production in natur...

Chitosan nanoparticles from marine squid protect liver cells against N-diethylnitrosoamine-induced hepatocellular carcinoma.

PubMed

Subhapradha, Namasivayam; Shanmugam, Vairamani; Shanmugam, Annaian

2017-09-01

Rationale of this study was framed to investigate the protective effect and anti-cancer property of nanoparticles based on chitosan isolated from squid, Sepioteuthis lessoniana, on hepatic cells in N-Nitrosodiethylamine-induced hepatocellular carcinoma in rats. The results conferred that the chitosan nanoparticle supplementation had a protective effect on liver cells by reducing the levels of marker enzymes and bilirubin and thus increasing the albumin levels. The level of reduced glutathione, ascorbic acid and α-tocopherol significantly increased in both post- and pre-treatment with chitosan nanoparticles. The levels of antioxidant enzymes were enhanced and lipid peroxidation products were diminished while treating nitrosodiethylamine-induced hepatocellular carcinoma with chitosan nanoparticles. Supplementation of chitosan nanoparticles had potent anti-hyperlipidemic property that was evidenced by monitoring the serum lipid levels and its components. Animals pre-treated with chitosan nanoparticles along with nitrosodiethylamine showed a significant reduction in the total cholesterol and triglycerides levels with increase in the levels of phospholipids and free fatty acids. Chitosan nanoparticles treated rats showed significant increment in high-density lipoprotein cholesterol and reduction in low-density lipoprotein and very low-density lipoprotein cholesterol when compared with levels in nitrosodiethylamine-induced hepatocellular carcinoma. Nitrosodiethylamine-induced carcinoma changes on circulation and hepatic antioxidant defense mechanism were regulated by chitosan nanoparticles, concluding that the chitosan nanoparticles have a potent protective effect on liver cells which might be due to its robust antioxidant and anti-lipidemic property. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of bioactive chitosan and sulfated chitosan from Doryteuthis singhalensis (Ortmann, 1891).

PubMed

Ramasamy, Pasiyappazham; Subhapradha, Namasivayam; Thinesh, Thangadurai; Selvin, Joseph; Selvan, Kanagaraj Muthamizh; Shanmugam, Vairamani; Shanmugam, Annaian

2017-06-01

Chitosan was extracted from the pen of squid Doryteuthis singhalensis and characterized using FT-IR, NMR, CHN, SEM and DSC analysis. Purified chitosan was sulfated with chlorosulfonic acid in N,N-dimethylformamide and the added sulfate group was confirmed with FT-IR analysis. The molecular weight and degree of deacetylation (DDA) of chitosan was found 226.6kDa and 83.76% respectively. Chitosan exhibited potent antioxidant activity evidenced by reducing power, chelating ability on ferrous ions and scavenging activity on DPPH, superoxide and hydroxyl radicals. The anticoagulant assay using activated partial thromboplastin time (APTT) and prothrombin time (PT) showed chitosan as a strong anticoagulant. The results of this study showed possibility of using D. singhalensis pen as a non-conventional source of natural antioxidants and anticoagulant which can be incorporated in functional food formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Crystal structure of the complex of carboxypeptidase A with a strongly bound phosphonate in a new crystalline form: comparison with structures of other complexes.

PubMed

Kim, H; Lipscomb, W N

1990-06-12

O-[[(1R)-[[N-(Phenylmethoxycarbonyl)-L-alanyl]amino]ethyl] hydroxyphosphinyl]-L-3-phenyllacetate [ZAAP(O)F], an analogue of (benzyloxycarbonyl)-Ala-Ala-Phe or (benzyloxycarbonyl)-Ala-Ala-phenyllactate, binds to carboxypeptidase A with great affinity (Ki = 3 pM). Similar phosphonates have been shown to be transition-state analogues of the CPA-catalyzed hydrolysis [Hanson, J. E., Kaplan, A. P., & Bartlett, P. A. (1989) Biochemistry 28, 6294-6305]. In the present study, the structure of the complex of this phosphonate with carboxypeptidase A has been determined by X-ray crystallography to a resolution of 2.0 A. The complex crystallizes in the space group P2(1)2(1)2(1) with cell dimensions a = 61.9 A, b = 67.2 A, and c = 76.2 A. The structure of the complex was solved by molecular replacement. Refinement of the structure against 20,776 unique reflections between 10.0 and 2.0 A yields a crystallographic residual of 0.193, including 140 water molecules. The two phosphinyl oxygens of the inhibitor bind to the active-site zinc at 2.2 A on the electrophilic (Arg-127) side and 3.1 A on the nucleophilic (Glu-270) side. Various features of the binding mode of this phosphonate inhibitor are consistent with the hypothesis that carboxypeptidase A catalyzed hydrolysis proceeds through a general-base mechanism in which the carbonyl carbon of the substrate is attacked by Zn-hydroxyl (or Zn-water). An unexpected feature of the bound inhibitor, the cis carbamoyl ester bond at the benzyloxycarbonyl linkage to alanine, allows the benzyloxycarbonyl phenyl ring of the inhibitor to interact favorably with Tyr-198. This complex structure is compared with previous structures of carboxypeptidase A, including the complexes with the potato inhibitor, a hydrated keto methylene substrate analogue, and a phosphonamidate inhibitor. Comparisons are also made with the complexes of thermolysin with some phosphonamidate inhibitors.

Synthesis and characterization of phosphonates from methyl linoleate and vegetable oils

USDA-ARS?s Scientific Manuscript database

Phosphonates were synthesized on a medium scale (~200 g) from three lipids: methyl linoleate (MeLin), high-oleic sunflower oil (HOSO), and soybean oil (SBO), and three dialkyl phosphites: methyl, ethyl, and n-butyl, using radical initiator. A staged addition of the lipid and the initiator was needed...

Development of Oseltamivir Phosphonate Congeners as Anti-Influenza Agents

PubMed Central

Cheng, Ting-Jen R.; Weinheimer, Steven; Tarbet, E. Bart; Jan, Jia-Tsrong; Cheng, Yih-Shyun E.; Shie, Jiun-Jie; Chen, Chun-Lin; Chen, Chih-An; Hsieh, Wei-Che; Huang, Pei-Wei; Lin, Wen-Hao; Wang, Shi-Yun; Fang, Jim-Min; Hu, Oliver Yoa-Pu; Wong, Chi-Huey

2012-01-01

Oseltamivir phosphonic acid (tamiphosphor, 3a), its monoethyl ester (3c), guanidino-tamiphosphor (4a) and its monoethyl ester (4c) are potent inhibitors of influenza neuraminidases. They inhibit the replication of influenza viruses, including the oseltamivir-resistant H275Y strain, at low nM to pM levels, and significantly protect mice from infection with lethal doses of influenza viruses when orally administered with 1 mg/kg or higher doses. These compounds are stable in simulated gastric fluid, liver microsomes and human blood, and are largely free from binding to plasma proteins. Pharmacokinetic properties of these inhibitors are thoroughly studied in dogs, rats and mice. The absolute oral bioavailability of these compounds was lower than 12%. No conversion of monoester 4c to phosphonic acid 4a was observed in rats after intravenous administration, but partial conversion of 4c was observed with oral administration. Advanced formulation may be investigated to develop these new anti-influenza agents for better therapeutic use. PMID:23009169

Gas chromatography-mass spectrometric studies of O-alkyl O-2-(N,N-dialkylamino) ethyl alkylphosphonites(phosphonates) for chemical weapons convention verification.

PubMed

Saeidian, Hamid; Babri, Mehran; Ramezani, Atefeh; Ashrafi, Davood; Sarabadani, Mansour; Naseri, Mohammad Taghi

2013-01-01

The electron ionization (EI) mass spectra of a series of O-alkyl O-2-(N,N-dialkylaminolethyl alkylphosphonites(phosphonates), which are precursors of nerve agents, were studied for Chemical Weapons Convention (CWC) verification. General El fragmentation pathways were constructed and discussed. Proposed fragment structures were confirmed through analyzing fragment ions of deuterated analogs and density functional theory (DFT) calculations. The observed fragment ions are due to different fragmentation pathways such as hydrogen and McLafferty+1 rearrangements, alkene, amine and alkoxy elimination by alpha- or beta-cleavage process. Fragment ions distinctly allow unequivocal identification of the interested compounds including those of isomeric compounds. The presence and abundance of fragment ions were found to depend on the size and structure of the alkyl group attached to nitrogen, phosphorus and oxygen atoms.

The novel application of chitosan: Effects of cross-linked chitosan on the fire performance of thermoplastic polyurethane.

PubMed

Zhang, Sheng; Liu, Xiaodong; Jin, Xiaodong; Li, Hongfei; Sun, Jun; Gu, Xiaoyu

2018-06-01

In this paper, a novel flame retardant (ACS) was prepared by crosslinking chitosan with bis-(4-formylphenyl)-phenyl-phosphonate (ABPO). ACS in association with ammonium polyphosphate (APP) and organic modified montmorillonite (OMMT) were used to prepare flame retardant thermoplastic polyurethane (TPU) composite through melt blending. For the TPU sample containing 10% flame retardants, the limiting oxygen index was increased from 20.8 to 29.0%, the vertical burning (UL-94) rating was upgraded from no rating to V-0, and the peak heat release rate was decreased from 1090 to 284 kW/m 2 . The thermal gravity analysis (TGA) indicated that ACS had excellent char formation ability and could greatly enhance the thermal stability of TPU. The tensile strength and elongation at break for flame retardant sample could reach 16.5 MPa and 1443% respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis and characterization of phosphonates from methyl linoleate and vegetable oils

USDA-ARS?s Scientific Manuscript database

Phosphonates were synthesized on a medium scale (~200 g) from three lipids: methyl linoleate (MeLin), high-oleic sunflower oil (HOSO) and soybean oil (SBO), and three dialkyl phosphites: methyl, ethyl and n-butyl, using a radical initiator. A staged addition of the lipid and the initiator to the dia...

Synthesis and characterization of phosphonates from methyl linoleate and vegetable oils

USDA-ARS?s Scientific Manuscript database

Phosphonates were synthesized on a medium scale (~200 g) from three lipids–methyl linoleate (MeLin), high-oleic sunflower oil (HOSO) and soybean oil (SBO), and three dialkyl phosphites–methyl, ethyl and n-butyl, using a radical initiator. A staged addition of the lipid and the initiator was used to ...

Methyleneation of peptides by N,N,N,N-tetramethylethylenediamine (TEMED) under conditions used for free radical polymerization: a mechanistic study.

PubMed

Shirangi, Mehrnoosh; Sastre Toraño, Javier; Sellergren, Börje; Hennink, Wim E; Somsen, Govert W; van Nostrum, Cornelus F

2015-01-21

Free radical polymerization is often used to prepare protein and peptide-loaded hydrogels for the design of controlled release systems and molecular imprinting materials. Peroxodisulfates (ammonium peroxodisulfates (APS) or potassium peroxodisulfates (KPS)) with N,N,N,N-tetramethylethylenediamine (TEMED) are frequently used as initiator and catalyst. However, exposure to these free radical polymerization reagents may lead to modification of the protein and peptide. In this work, we show the modification of lysine residues by ammonium peroxodisulfate (APS)/TEMED of the immunostimulant thymopentin (TP5). Parallel studies on a decapeptide and a library of 15 dipeptides were performed to reveal the mechanism of modification. LC-MS of APS/TEMED-exposed TP5 revealed a major reaction product with an increased mass (+12 Da) with respect to TP5. LC-MS(2) and LC-MS(3) were performed to obtain structural information on the modified peptide and localize the actual modification site. Interpretation of the obtained data demonstrates the formation of a methylene bridge between the lysine and arginine residue in the presence of TEMED, while replacing TEMED with a sodium bisulfite catalyst did not show this modification. Studies with the other peptides showed that the TEMED radical can induce methyleneation on peptides when lysine is next to arginine, proline, cysteine, aspargine, glutamine, histidine, tyrosine, tryptophan, and aspartic acid residues. Stability of peptides and protein needs to be considered when using APS/TEMED in in situ polymerization systems. The use of an alternative catalyst such as sodium bisulfite may preserve the chemical integrity of peptides during in situ polymerization.

Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

DOE PAGES

Zheng, Tao; Yang, Zaixing; Gui, Daxiang; ...

2017-05-30

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. We overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. Furthermore, these compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest voidmore » volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism.« less

Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

PubMed Central

Zheng, Tao; Yang, Zaixing; Gui, Daxiang; Liu, Zhiyong; Wang, Xiangxiang; Dai, Xing; Liu, Shengtang; Zhang, Linjuan; Gao, Yang; Chen, Lanhua; Sheng, Daopeng; Wang, Yanlong; Diwu, Juan; Wang, Jianqiang; Zhou, Ruhong; Chai, Zhifang; Albrecht-Schmitt, Thomas E.; Wang, Shuao

2017-01-01

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. Herein, we overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. These compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest void volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism. PMID:28555656

Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

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

Zheng, Tao; Yang, Zaixing; Gui, Daxiang

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. We overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. Furthermore, these compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest voidmore » volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism.« less

Adsorption properties of congo red from aqueous solution onto N,O-carboxymethyl-chitosan.

PubMed

Wang, Li; Wang, Aiqin

2008-03-01

N,O-carboxymethyl-chitosans (N,O-CMC) with different degree of substitution (DS) were synthesized under heterogeneous conditions by controlling the reaction temperature. The factors influencing adsorption capacity of N,O-CMC such as the DS of N,O-CMC, initial pH value of the dye solution and adsorption temperature for anionic dye congo red (CR) were investigated. Compared with chitosan (78.90 mg/g), N,O-CMC with the DS of 0.35 exhibited much higher adsorption capacity (330.62 mg/g) for CR at the same adsorption conditions. The adsorption kinetics and isotherms showed that the sorption processes were better fitted by pseudo-second-order equation and the Langmuir equation, respectively. The adsorption mechanism of N,O-CMC was also discussed by means of IR and XPS spectra. The results in this study indicated that N,O-CMC was an attractive candidate for removing CR from the dye wastewater.

Single and double C-Cl-activation of methylene chloride by P,N-ligand coordinated rhodium complexes.

PubMed

Blank, Benoît; Glatz, Germund; Kempe, Rhett

2009-02-02

Two in one: The simultaneous formation of bimetallic mu-methylene bridged Rh(III) complexes as well as dimeric Rh(III) complexes with terminal chloromethyl groups is observed for P,N-ligand stabilized Rh(I) complexes by C-Cl bond activation of methylene chloride. A mechanistic proposal for the formation of both activation products is also discussed. The synthesis of Rh(I) complexes with P-functionalized aminopyridine ligands is reported as well as the first simultaneous observation of a single and double activation of C-Cl bonds of methylene chloride affording both a dimeric Rh(III) complex bearing terminal CH(2)Cl groups in addition to a binuclear Rh(III) complex with a bridging mu-CH(2) group. The structures of the oxidative addition products were obtained by X-ray diffraction studies and NMR experiments were performed to elucidate some aspects of the reaction pathway.

Epoxy Phosphonate Crosslinkers for Providing Flame Resistance to Cotton Textiles

USDA-ARS?s Scientific Manuscript database

Two new monomers (2-methyl-oxiranylmethyl)-phosphonic acid dimethyl ester (3) and [2-(dimethoxy-phosphorylmethyl)-oxyranylmethyl]-phosphonic acid dimethyl ester (6) were prepared and used with dicyandiamide (7) and citric acid (8) to impart flame resistance to cotton plain weave, twill, and 80:20-co...

N-Allylation of amines with allyl acetates using chitosan-immobilized palladium

EPA Science Inventory

A simple procedure for N-Allylation of allyl Acetates has been developed using a biodegradable and easily recyclable heterogeneous chitosan-supported palladium catalyst. The general methodology, applicable to wide range of substrates, has sustainable features that include a ligan...

Transport mechanism of chitosan-N-acetylcysteine, chitosan oligosaccharides or carboxymethyl chitosan decorated coumarin-6 loaded nanostructured lipid carriers across the rabbit ocular.

PubMed

Li, Jinyu; Tan, Guoxin; Cheng, Bingchao; Liu, Dandan; Pan, Weisan

2017-11-01

To facilitate the hydrophobic drugs modeled by coumarin-6 (Cou-6) acrossing the cornea to the anterior chamber of the rabbit eye, chitosan (CS) derivatives including chitosan-N-acetyl-l-cysteine (CS-NAC), chitosan oligosaccharides (COS) and carboxymethyl chitosan (CMCS) modified nanostructured lipid carriers (NLCs) were designed and characterized. We found that, with similar size distribution and positivecharges, different CS derivatives based on NLCs led to distinctive delivery performance. In vivo precorneal retention study on rabbits revealed that these CS derivatives coating exhibited a stronger resistant effect than Cou-6 eye drops and Cou-6-NLC (P<0.05), moreover, the AUC (0-∞) , C max and MRT (0-∞) of them followed the sequence of CMCS-Cou-6-NLC

Determination of the parameters of binding between lipopolysaccharide and chitosan and its N-acetylated derivative using a gravimetric piezoquartz biosensor.

PubMed

Naberezhnykh, G A; Gorbach, V I; Kalmykova, E N; Solov'eva, T F

2015-03-01

The interaction of endotoxin (lipopolysaccharide - LPS) with low molecular weight chitosan (5.5 kDa), its N-acylated derivative and chitoliposomes was studied using a gravimetric piezoelectric quartz crystal microbalance biosensor. The optimal conditions for the formation of a biolayer based on immobilized LPS on the resonator surface and its regeneration were elaborated. The association and dissociation rate constants for LPS binding to chitosans were determined and the affinity constants (Kaf) were calculated based on the data on changes in the oscillation frequency of the quartz crystal resonator. The Kaf values correlated with the ones obtained using other methods. The affinity of N-acylated chitosan binding to LPS was higher than that of the parent chitosan binding to LPS. Based on the results obtained, we suggest that water-soluble N-acylated derivatives of chitosan with low degree of substitution of amino groups could be useful compounds for endotoxin binding and neutralization. Copyright © 2015 Elsevier B.V. All rights reserved.

Functionalization of SBA-15 mesoporous silica by Cu-phosphonate units: Probing of synthesis route

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

Laskowski, Lukasz, E-mail: lukasz.laskowski@kik.pcz.pl; Czestochowa University of Technology, Institute of Physics, Al. Armii Krajowej 19, 42-201 Czestochowa; Laskowska, Magdalena, E-mail: magdalena.laskowska@onet.pl

2014-12-15

Mesoporous silica SBA-15 containing propyl-copper phosphonate units was investigated. The structure of mesoporous samples was tested by N{sub 2} isothermal sorption (BET and BHJ analysis), TEM microscopy and X-Ray scattering. Quantitative analysis EDX has given information about proportions between component atoms in the sample. Quantitative elemental analysis has been carried out to support EDX. To examine bounding between copper atoms and phosphonic units the Raman spectroscopy was carried out. As a support of Raman scattering, the theoretical calculations were made based on density functional theory, with the B3LYP method. By comparison of the calculated vibrational spectra of the molecule withmore » experimental results, distribution of the active units inside silica matrix has been determined. - Graphical abstract: The present study is devoted to mesoporous silica SBA-15 containing propyl-copper phosphonate units. The species were investigated to confirm of synthesis procedure correctness by the micro-Raman technique combined with DFT numerical simulations. Complementary research was carried out to test the structure of mesoporous samples. - Highlights: • SBA-15 silica functionalized with propyl-copper phosphonate units was synthesized. • Synthesis efficiency probed by Raman study supported with DFT simulations. • Homogenous distribution of active units was proved. • Synthesis route enables precise control of distance between copper ions.« less

Synthesis of mesoporous TiO2-curcumin nanoparticles for photocatalytic degradation of methylene blue dye.

PubMed

Abou-Gamra, Z M; Ahmed, M A

2016-07-01

Herein, we demonstrate a facile route for synthesis a new photocatalyst based on TiO2-curcumin nanoparticles for photodegradation of methylene blue dye under UV and visible light irradiation. The photocatalyst was prepared by sol-gel method using chitosan as biodegradable polymer. The crystalline and the nanostructure were characteristic X-ray diffraction [XRD], adsorption-desorption isotherm and high resolution transmission electron microscopy [HRTEM]. However, the optical features of the samples were investigated by a UV-visible spectrophotometer. It is obvious to notice the removal of the majority of methylene blue dye on a pure titania surface via adsorption mechanism owing to the high surface area and to the organized mesoporous nature of the solid sample. Incorporation of curcumin on titania surface changes the removal direction from adsorption to the photocatalytic pathway. Various photocatalytic experiments were performed to investigate the influence of initial dye concentration, weight of catalyst, stirring and light intensity on the photocatalytic degradation of methylene blue as primary pollutant model. Chemical oxygen demand [COD] test confirms the complete degradation of methylene blue dye. The exceptional photocatalytic reactivity of titania-curcumin nanoparticles is referred to reduction in band gap energy and to the facility of electron transfer from II* curcumin energy level to titania conduction band which increases the concentration of reactive oxygen superoxide radicals which in turn prevents the electron-hole recombination. The effect of various scavengers on the methylene blue dye degradation was investigated using ethanol, ascorbic acid and methyl viologen. The results have pointed out that O2(-) and HO(.) are considered the main active species in the degradation process. A plausible pathway and mechanism for the photocatalytic degradation of methylene blue by titania-curcumin nanoparticles were illustrated. Copyright © 2016 Elsevier B

Alkyl phosphonic acids and sulfonic acids in the Murchison meteorite

NASA Technical Reports Server (NTRS)

Cooper, George W.; Onwo, Wilfred M.; Cronin, John R.

1992-01-01

Homologous series of alkyl phosphonic acids and alkyl sulfonic acids, along with inorganic orthophosphate and sulfate, are identified in water extracts of the Murchison meteorite after conversion to their t-butyl dimethylsilyl derivatives. The methyl, ethyl, propyl, and butyl compounds are observed in both series. Five of the eight possible alkyl phosphonic acids and seven of the eight possible alkyl sulfonic acids through C4 are identified. Abundances decrease with increasing carbon number as observed of other homologous series indigenous to Murchison. Concentrations range downward from approximately 380 nmol/gram in the alkyl sulfonic acid series, and from 9 nmol/gram in the alkyl phosphonic acid series.

Nanolayer formation on titanium by phosphonated gelatin for cell adhesion and growth enhancement

PubMed Central

Zhou, Xiaoyue; Park, Shin-Hye; Mao, Hongli; Isoshima, Takashi; Wang, Yi; Ito, Yoshihiro

2015-01-01

Phosphonated gelatin was prepared for surface modification of titanium to stimulate cell functions. The modified gelatin was synthesized by coupling with 3-aminopropylphosphonic acid using water-soluble carbodiimide and characterized by 31P nuclear magnetic resonance and gel permeation chromatography. Circular dichroism revealed no differences in the conformations of unmodified and phosphonated gelatin. However, the gelation temperature was changed by the modification. Even a high concentration of modified gelatin did not form a gel at room temperature. Time-of-flight secondary ion mass spectrometry showed direct bonding between the phosphonated gelatin and the titanium surface after binding. The binding behavior of phosphonated gelatin on the titanium surface was quantitatively analyzed by a quartz crystal microbalance. Ellipsometry showed the formation of a several nanometer layer of gelatin on the surface. Contact angle measurement indicated that the modified titanium surface was hydrophobic. Enhancement of the attachment and spreading of MC-3T3L1 osteoblastic cells was observed on the phosphonated gelatin-modified titanium. These effects on cell adhesion also led to growth enhancement. Phosphonation of gelatin was effective for preparation of a cell-stimulating titanium surface. PMID:26366080

Geminal difunctionalization of α-diazo arylmethylphosphonates: synthesis of fluorinated phosphonates.

PubMed

Zhou, Yujing; Zhang, Yan; Wang, Jianbo

2016-11-08

A general approach towards diverse fluorinated phosphonates via geminal difunctionalization reactions of α-diazo arylmethylphosphonates is described. The diazo functionality (RR'C[double bond, length as m-dash]N 2 ) is successfully converted to RR'CF 2 , RR'CHF, RR'CFBr or RR'CFNR'' 2 groups by employing different fluorination reagents. A variety of fluorinated organophosphorus compounds were readily accessed in good to excellent yields from a common type of precursor.

Ab initio computational study of –N-C and –O-C bonding formation : functional group modification reaction based chitosan

NASA Astrophysics Data System (ADS)

Siahaan, P.; Salimah, S. N. M.; Sipangkar, M. J.; Hudiyanti, D.; Djunaidi, M. C.; Laksitorini, M. D.

2018-04-01

Chitosan application in pharmaceutics and cosmeceutics industries is limited by its solubility issue. Modification of -NH2 and -OH fuctional groups of chitosan by adding carboxyl group has been shown to improve its solubility and application. Attempt to synthesize carboxymethyl chitosan (CMC) from monocloroacetic acid (MCAA) has been done prior this report. However no information is available wether –OH (-O-C bonding formation) or -NH2 (-N-C bonding formation) is the preference for - CH2COOH to attach. In the current study, the reaction mechanism between chitosan and MCAA reactants into carboxymethyl chitosan (CMC) was examined by computational approach. Dimer from of chitosan used as a molecular model in calculation All the molecular structure involved in the reaction mechanism was optimized by ab initio computational on the theory and basis set HF/6-31G(d,p). The results showed that the - N-C bonding formation via SN2 than the -O-C bonding formation via SN2 which have activation energy 469.437 kJ/mol and 533.219 kJ/mol respectively. However, the -O-C bonding formation more spontaneous than the -N-C bonding formation because ΔG the formation of O-CMC-2 reaction is more negative than ΔG of formation N-CMC-2 reaction is -4.353 kJ/mol and -1.095 kJ/mol respectively. The synthesis of N,O-CMC first forms -O-CH2COOH, then continues to form -NH-CH2COOH. This information is valuable to further optimize the reaction codition for CMC synthesis.

Isopropyl methyl phosphonic acid (IMPA)

Integrated Risk Information System (IRIS)

Isopropyl methyl phosphonic acid ( IMPA ) ; CASRN 1832 - 54 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assess

Antiviral activity of silver nanoparticle/chitosan composites against H1N1 influenza A virus

NASA Astrophysics Data System (ADS)

Mori, Yasutaka; Ono, Takeshi; Miyahira, Yasushi; Nguyen, Vinh Quang; Matsui, Takemi; Ishihara, Masayuki

2013-02-01

Silver nanoparticle (Ag NP)/chitosan (Ch) composites with antiviral activity against H1N1 influenza A virus were prepared. The Ag NP/Ch composites were obtained as yellow or brown floc-like powders following reaction at room temperature in aqueous medium. Ag NPs (3.5, 6.5, and 12.9 nm average diameters) were embedded into the chitosan matrix without aggregation or size alternation. The antiviral activity of the Ag NP/Ch composites was evaluated by comparing the TCID50 ratio of viral suspensions treated with the composites to untreated suspensions. For all sizes of Ag NPs tested, antiviral activity against H1N1 influenza A virus increased as the concentration of Ag NPs increased; chitosan alone exhibited no antiviral activity. Size dependence of the Ag NPs on antiviral activity was also observed: antiviral activity was generally stronger with smaller Ag NPs in the composites. These results indicate that Ag NP/Ch composites interacting with viruses exhibit antiviral activity.

Synthesis and X-ray structures of dilithium complexes of the phosphonate anions [PhP(E)(N(t)Bu)(2)](2-) (E = O, S, Se, Te) and dimethylaluminum derivatives of [PhP(E)(N(t)Bu)(NH(t)Bu)](-) (E = S, Se).

PubMed

Briand, Glen G; Chivers, Tristram; Krahn, Mark; Parvez, Masood

2002-12-16

The dilithium salts of the phosphonate dianions [PhP(E)(N(t)Bu)(2)](2-) (E = O, S, Se) are generated by the lithiation of [PhP(E)(NH(t)Bu)(2)] with n-butyllithium. The formation of the corresponding telluride (E = Te) is achieved by oxidation of [Li(2)[PhP(N(t)Bu)(2)

An Overview of the Protective Effects of Chitosan and Acetylated Chitosan Oligosaccharides against Neuronal Disorders.

PubMed

Hao, Cui; Wang, Wei; Wang, Shuyao; Zhang, Lijuan; Guo, Yunliang

2017-03-23

Chitin is the second most abundant biopolymer on Earth and is mainly comprised of a marine invertebrate, consisting of repeating β-1,4 linked N-acetylated glucosamine units, whereas its N-deacetylated product, chitosan, has broad medical applications. Interestingly, chitosan oligosaccharides have therapeutic effects on different types of neuronal disorders, including, but not limited to, Alzheimer's disease, Parkinson's disease, and nerve crush injury. A common link among neuronal disorders is observed at a sub-cellular level, such as atypical protein assemblies and induced neuronal death. Chronic activation of innate immune responses that lead to neuronal injury is also common in these diseases. Thus, the common mechanisms of neuronal disorders might explain the general therapeutic effects of chitosan oligosaccharides and their derivatives in these diseases. This review provides an update on the pathogenesis and therapy for neuronal disorders and will be mainly focused on the recent progress made towards the neuroprotective properties of chitosan and acetylated chitosan oligosaccharides. Their structural features and the underlying molecular mechanisms will also be discussed.

Hydrothermal synthesis and crystal structure of alkaline earth metal (Mg, Ca) based on 2,5-Dimethylbenzene-1,4-diylbis(methylene) diphosphonic acid

NASA Astrophysics Data System (ADS)

Xie, Y. C.; Cheng, Q. R.; Pan, Z. Q.

2018-02-01

New magnesium phosphonates Mg(H2L)31 (H4L = 2,5-dimethylbenzene-1,4 -diylbis(methylene)diphosphonic acid) and Ca(H2L)·2H2O 2 have been hydrothermally synthesized from H4L and the corresponding metal salts. Complex 1 and 2 have been characterized by IR, powder and single-crystal X-ray diffraction methods. Complex 1 crystallizes in trigonal space group R-3c and complex 2 belongs to the triclinic space group. The complexes both form two-dimensional (2D) network structure and show three-dimensional (3D) network through hydrogen bonds. Thermal stability of complex 1 and 2 have also been investigated. CCDC: 1534599 for 1; 1536423 for 2.

A New Epoxy Bis-Phosphonate Crosslinker for Durable Fire Retardancy on Cotton

USDA-ARS?s Scientific Manuscript database

A new epoxy bis-phosphonate crosslinker for cotton [2-(dimethoxy-phosphorylmethyl)-oxiranylmethyl]-phosphonic acid dimethyl ester was prepared in two steps from 3-chloro-2-chloromethylpropene in 55% yield. The new monomer was characterized by proton and carbon NMR and GC-mass spectrometry. This cro...

Use of hybrid chitosan membranes and N1E-115 cells for promoting nerve regeneration in an axonotmesis rat model.

PubMed

Amado, S; Simões, M J; Armada da Silva, P A S; Luís, A L; Shirosaki, Y; Lopes, M A; Santos, J D; Fregnan, F; Gambarotta, G; Raimondo, S; Fornaro, M; Veloso, A P; Varejão, A S P; Maurício, A C; Geuna, S

2008-11-01

Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to develop and test hybrid chitosan membranes to use in peripheral nerve reconstruction, either alone or enriched with N1E-115 neural cells. Hybrid chitosan membranes were tested in vitro, to assess their ability in supporting N1E-115 cell survival and differentiation, and in vivo to assess biocompatibility as well as to evaluate their effects on nerve fiber regeneration and functional recovery after a standardized rat sciatic nerve crush injury. Functional recovery was evaluated using the sciatic functional index (SFI), the static sciatic index (SSI), the extensor postural thrust (EPT), the withdrawal reflex latency (WRL) and ankle kinematics. Nerve fiber regeneration was assessed by quantitative stereological analysis and electron microscopy. All chitosan membranes showed good biocompatibility and proved to be a suitable substrate for plating the N1E-115 cellular system. By contrast, in vivo nerve regeneration assessment after crush injury showed that the freeze-dried chitosan type III, without N1E-115 cell addition, was the only type of membrane that significantly improved posttraumatic axonal regrowth and functional recovery. It can be thus suggested that local enwrapping with this type of chitosan membrane may represent an effective approach for the improvement of the clinical outcome in patients receiving peripheral nerve surgery.

Cytotoxicity and metal ions removal using antibacterial biodegradable hydrogels based on N-quaternized chitosan/poly(acrylic acid).

PubMed

Mohamed, Riham R; Elella, Mahmoud H Abu; Sabaa, Magdy W

2017-05-01

Physically crosslinked hydrogels resulted from interaction between N,N,N-trimethyl chitosan chloride (N-Quaternized Chitosan) (NQC) and poly(acrylic acid) (PAA) were synthesized in different weight ratios (3:1), (1:1) and (1:3) taking the following codes Q3P1, Q1P1 and Q1P3, respectively. Characterization of the mentioned hydrogels was done using several analysis tools including; FTIR, XRD, SEM, TGA, biodegradation in simulated body fluid (SBF) and cytotoxicity against HepG-2 liver cancer cells. FTIR results proved that the prepared hydrogels were formed via electrostatic and H-bonding interactions, while XRD patterns proved that the prepared hydrogels -irrespective to their ratios- were more crystalline than both matrices NQC and PAA. TGA results, on the other hand, revealed that Q1P3 hydrogel was the most thermally stable compared to the other two hydrogels (Q3P1 and Q1P1). Biodegradation tests in SBF proved that these hydrogels were more biodegradable than the native chitosan. Examination of the prepared hydrogels for their potency in heavy metal ions removal revealed that they adsorbed Fe (III) and Cd (II) ions more than chitosan, while they adsorbed Cr (III), Ni (II) and Cu (II) ions less than chitosan. Moreover, testing the prepared hydrogels as antibacterial agents towards several Gram positive and Gram negative bacteria revealed their higher antibacterial activity as compared with NQC when used alone. Evaluating the cytotoxic effect of these hydrogels on an in vitro human liver cancer cell model (HepG-2) showed their good cytotoxic activity towards HepG-2. Moreover, the inhibition rate increased with increasing the hydrogels concentration in the culture medium. Copyright © 2017 Elsevier B.V. All rights reserved.

Chitosan-edible oil based materials as upgraded adsorbents for textile dyes.

PubMed

Dos Santos, Clayane Carvalho; Mouta, Rodolpho; Junior, Manoel Carvalho Castro; Santana, Sirlane Aparecida Abreu; Silva, Hildo Antonio Dos Santos; Bezerra, Cícero Wellington Brito

2018-01-15

Biopolymer chitosan is a low cost, abundant, environmentally friendly, very selective and efficient anionic dyes adsorbent, being a promising material for large-scale removal of dyes from wastewater. However, raw chitosan (CS) is an ineffective cationic dyes adsorbent and its performance is pH sensitive, thus, CS modifications that address these issues need to be developed. Here, we report the preparation and characterization of two new CS modifications using edible oils (soybean oil or babassu oil), and their adsorption performance for two dyes, one anionic (remazol red, RR) and one cationic (methylene blue, MB). Both modifications extended the pH range of RR adsorption. The babassu oil modification increased adsorption capacity of the cationic dye MB, whereas the soybean oil modification increased that of RR. Such improvements demonstrate the potential of these two new CS modifications as adsorbent candidates for controlling dyes pollution in effluents. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Novel Multi-Phosphonate Surface Treatment of Titanium Dental Implants: A Study in Sheep

PubMed Central

von Salis-Soglio, Marcella; Stübinger, Stefan; Sidler, Michéle; Klein, Karina; Ferguson, Stephen J.; Kämpf, Käthi; Zlinszky, Katalin; Buchini, Sabrina; Curno, Richard; Péchy, Péter; Aronsson, Bjorn-Owe; von Rechenberg, Brigitte

2014-01-01

The aim of the present study was to evaluate a new multi-phosphonate surface treatment (SurfLink®) in an unloaded sheep model. Treated implants were compared to control implants in terms of bone to implant contact (BIC), bone formation, and biomechanical stability. The study used two types of implants (rough or machined surface finish) each with either the multi-phosphonate Wet or Dry treatment or no treatment (control) for a total of six groups. Animals were sacrificed after 2, 8, and 52 weeks. No adverse events were observed at any time point. At two weeks, removal torque showed significantly higher values for the multi-phosphonate treated rough surface (+32% and +29%, Dry and Wet, respectively) compared to rough control. At 52 weeks, a significantly higher removal torque was observed for the multi-phosphonate treated machined surfaces (+37% and 23%, Dry and Wet, respectively). The multi-phosphonate treated groups showed a positive tendency for higher BIC with time and increased new-old bone ratio at eight weeks. SEM images revealed greater amounts of organic materials on the multi-phosphonate treated compared to control implants, with the bone fracture (from the torque test) appearing within the bone rather than at the bone to implant interface as it occurred for control implants. PMID:25215424

Synthesis and Structural Studies of Calcium and Magnesium Phosphinate and Phosphonate Compounds

NASA Astrophysics Data System (ADS)

Bampoh, Victoria Naa Kwale

The work presented herein describes synthetic methodologies leading to the design of a wide array of magnesium and calcium based phosphinate and phosphonates with possible applications as bone scaffolding materials or additives to bone cements. The challenge to the chemistry of the alkaline earth phosphonate target compounds includes poor solubility of compounds, and poorly understood details on the control of the metal's coordination environment. Hence, less is known on phosphonate based alkaline earth metal organic frameworks as compared to transition metal phosphonates. Factors governing the challenges in obtaining crystalline, well-defined magnesium and calcium solids lie in the large metal diameters, the absence of energetically available d-orbitals to direct metal geometry, as well as the overall weakness of the metal-ligand bonds. A significant part of this project was concerned with the development of suitable reaction conditions to obtain X-ray quality crystals of the reaction products to allow for structural elucidation of the novel compounds. Various methodologies to aid in crystal growth including hydrothermal methods and gel crystallization were employed. We have used phosphinate and phosphonate ligands with different number of phosphorus oxygen atoms as well as diphosphonates with different linker lengths to determine their effects on the overall structural features. An interesting correlation is observed between the dimensionality of products and the increasing number of donor oxygen atoms in the ligands as we progress from phosphinic acid to the phosphorous acids. As an example, monophosphinate ligand only yielded one-dimensional compounds, whereas the phosphonates crystallize as one and two-dimensional compounds, and the di- and triphosphonate based compounds display two or three-dimensional geometries. This thesis provides a selection of calcium and magnesium compounds with one-dimensional geometry, as represented in a calcium phosphinate to novel

Synthesis of a new family of acyclic nucleoside phosphonates, analogues of TPases transition states.

PubMed

Dayde, Bénédicte; Benzaria, Samira; Pierra, Claire; Gosselin, Gilles; Surleraux, Dominique; Volle, Jean-Noël; Pirat, Jean-Luc; Virieux, David

2012-05-07

A 6-step procedure was developed for the synthesis of a new family of acyclic nucleoside phosphonates (ANPs), "PHEEPA" [(2-pyrimidinyl-2-(2-hydroxyethoxy)ethyl)phosphonic acids] in overall yields ranging from 4.5% to 32%. These compounds, which possess on one side a hydroxy function and on the other side a phosphonate group, can be considered either as potential antiviral agents or as transition state analogues of nucleoside phosphorylases such as thymidine phosphorylase.

Documents for SBAR Panel: Methylene Chloride and N-Methylpyrrolidone; Regulation of Certain Uses Under TSCA Section 6(a)

EPA Pesticide Factsheets

SBAR panel to to address the risks resulting from the manufacture, import, processing, distribution in commerce, and use of chemicals, as well as any manner or method of disposal of chemicals: n-methylpyrrolidone (NMP) and methylene chloride

Bacterial Degradation of Phosphonates Bound to High-Molecular-Weight Dissolved Organic Matter Produces Methane and Other Hydrocarbons

NASA Astrophysics Data System (ADS)

Sosa, O.; Ferron Smith, S.; Karl, D. M.; DeLong, E.; Repeta, D.

2016-02-01

The biological degradation of dissolved organic matter (DOM) plays important roles in the carbon cycle and energy balance of the ocean. Yet, the biochemical pathways that drive DOM turnover remain to be fully characterized. In this study, we tested the ability of two open ocean bacterial isolates (a Pseudomonas stutzeri strain (Gammaproteobacteria) and a Sulfitobacter isolate (Alphaproteobacteria)) to degrade DOM phosphonates. Each isolate encoded a complete phosphonate degradation pathway in its genome, and each was able to degrade simple alkyl-phosphonates like methyl phosphonate, releasing methane (or other short chain hydrocarbon gases) as a result. We found that cultures incubated in the presence of HMW DOM polysaccharides also produced methane and other trace gases under aerobic conditions. To demonstrate that phosphonates were the source of these gases, we constructed a P. stutzeri mutant disabled in the phosphonate degradation pathway. Unlike the wild type, the mutant strain was deficient in the production of methane and other gases from HMW DOM-associated phosphonates. These observations support the hypothesis that DOM-bound methyl phosphonates may be a significant source of methane in the water column, and that bacterial degradation of these compounds likely contribute to the subsurface methane maxima observed throughout the world's oceans.

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase.

PubMed

Kim, In-Hae; Park, Yong-Kyu; Nishiwaki, Hisashi; Hammock, Bruce D; Nishi, Kosuke

2015-11-15

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase (sEH) were investigated. First, a series of alkyl or aryl groups were substituted on the carbon alpha to the phosphonate function in amide compounds to see whether substituted phosphonates can act as a secondary pharmacophore. A tert-butyl group (16) on the alpha carbon was found to yield most potent inhibition on the target enzyme. A 4-50-fold drop in inhibition was induced by other substituents such as aryls, substituted aryls, cycloalkyls, and alkyls. Then, the modification of the O-substituents on the phosphonate function revealed that diethyl groups (16 and 23) were preferable for inhibition to other longer alkyls or substituted alkyls. In amide compounds with the optimized diethylphosphonate moiety and an alkyl substitution such as adamantane (16), tetrahydronaphthalene (31), or adamantanemethane (36), highly potent inhibitions were gained. In addition, the resulting potent amide-phosphonate compounds had reasonable water solubility, suggesting that substituted phosphonates in amide inhibitors are effective for both inhibition potency on the human sEH and water solubility as a secondary pharmacophore. Copyright © 2015 Elsevier Ltd. All rights reserved.

Self-assembled titanium phosphonate nanomaterial having a mesoscopic void space and its optoelectronic application.

PubMed

Pramanik, Malay; Patra, Astam K; Bhaumik, Asim

2013-04-14

Here we report the synthesis of a new crystalline titanium phosphonate material (HTiP-7) having a self-assembled nanostructure and a mesoscopic void space without the aid of any surfactant or templating agent. The material has been synthesized hydrothermally through the reaction between benzene-1,3,5-triphosphonic acid (BTPA) and titanium(iv) isopropoxide at neutral pH at 453 K for 24 h. This hybrid phosphonate material has been thoroughly characterized by powder X-ray diffraction, N2 sorption, HR TEM, FE SEM, TG-DTA, FT IR and UV-Vis diffuse reflectance spectroscopic studies. Two very well-known software packages, REFLEX and CELSIZ unit cell refinement programs, are employed to establish the triclinic crystal phase of this hybrid material (HTiP-7). Very tiny nanocrystals of HTiP-7 self-aggregated to form spherical nanoparticles of dimension ca. 25 nm together with a mesoscopic void space and good BET surface area (255 m(2) g(-1)). The framework is thermally stable up to 650 K. The material showed excellent carrier mobility for photocurrent generation in the presence of a photosensitizer molecule (Rose Bengal). To the best of our knowledge this is the first report of a photon-to-electron energy transfer process over a dye doped titanium phosphonate nanomaterial.

Methylene blue inhibits the asexual development of vivax malaria parasites from a region of increasing chloroquine resistance

PubMed Central

Suwanarusk, Rossarin; Russell, Bruce; Ong, Alice; Sriprawat, Kanlaya; Chu, Cindy S.; PyaePhyo, Aung; Malleret, Benoit; Nosten, François; Renia, Laurent

2015-01-01

Objectives Methylene blue, once discarded due to its unsettling yet mild side effects, has now found a renewed place in the pharmacopoeia of modern medicine. The continued spread of drug-resistant Plasmodium vivax and Plasmodium falciparum has also led to a recent re-examination of methylene blue's potent antimalarial properties. Here we examine the ex vivo susceptibility profile of Plasmodium spp. isolates to methylene blue; the isolates were from a region on the Thai–Myanmar border where there are increasing rates of failure when treating vivax malaria with chloroquine. Methods To do this we used a newly developed ex vivo susceptibility assay utilizing flow cytometry and a portable flow cytometer with a near-UV laser. Results P. vivax (median methylene blue IC50 3.1 nM, IQR 1.7–4.3 nM) and P. falciparum (median methylene blue IC50 1.8 nM, IQR 1.6–2.3 nM) are susceptible to methylene blue treatment at physiologically relevant levels. Unfortunately, the addition of chloroquine to combination treatments with methylene blue significantly reduces the ex vivo effectiveness of this molecule. Conclusions Our data support further efforts to employ methylene blue as a safe, low-cost antimalarial to treat drug-resistant malaria. PMID:25150147

Synthesis of biodegradable plastic from tapioca with N-Isopropylacrylamid and chitosan using glycerol as plasticizer

NASA Astrophysics Data System (ADS)

Syaubari; Safwani, S.; Riza, M.

2018-04-01

One of natural polymers that can be used as raw material in the manufacture of biodegradable plastic is tapioca and chitosan. The addition of other compounds such as glycerol as plasticizer is to improve the characteristics of the plastic that already produced. N- Isopropylacrylamid (NIPAm) is an organic compound that can be synthesized into a polymer or polymer grafting which also biodegradable too. This research aims tostudy the synthesis of biodegradable plastics from tapioca with the addition of chitosan, NIPAm, poly(NIPAm) and analyze the characteristics of biodegradable plastics that already produced. This research was done in three stages, there are (1) polymerization NIPAm, (2) the grafting of chitosan-poly NIPAm and (3) the synthesis of biodegradable plastics from starch mixture with variation of addition chitosan, NIPAm, poly(NIPAm), chitosan-graft-poly(NIPAm) and also variations of glycerol as plasticizer. The results of this research is a thin sheet of plastic which is will get analyzed for the characteristics of functional groups, mechanical, morphological and its biodegradability. FTIR spectra showed the grafting process with the new group formation of CO single-bond at 850 cm-1. Plastic with the addition of NIPAm and 1 ml glycerol has the highest tensile strength value about 31.1 MPa. Plastic with poly(NIPAm) and 4 ml glycerol produces the highest elongation value about 153.72%. Plastic with Chitosan-graft-poly(NIPAm) with 1 ml glycerol has the longest biodegradation because of the small mass-loss for six weeks which is about 6.6%.

Vitamin D-fortified chitosan films from mushroom waste

USDA-ARS?s Scientific Manuscript database

Brown mushroom (Agaricus bisporus) stalk bases from mushroom waste were treated with UV-B light to rapidly increase vitamin D2 content. Chitin was also recovered from this waste and converted into chitosan by N-deacetylation. FTIR spectra showed that the mushroom chitosan were similar to chitosan fr...

Comparison of Zirconium Phosphonate-Modified Surfaces for Immobilizing Phosphopeptides and Phosphate-Tagged Proteins.

PubMed

Forato, Florian; Liu, Hao; Benoit, Roland; Fayon, Franck; Charlier, Cathy; Fateh, Amina; Defontaine, Alain; Tellier, Charles; Talham, Daniel R; Queffélec, Clémence; Bujoli, Bruno

2016-06-07

Different routes for preparing zirconium phosphonate-modified surfaces for immobilizing biomolecular probes are compared. Two chemical-modification approaches were explored to form self-assembled monolayers on commercially available primary amine-functionalized slides, and the resulting surfaces were compared to well-characterized zirconium phosphonate monolayer-modified supports prepared using Langmuir-Blodgett methods. When using POCl3 as the amine phosphorylating agent followed by treatment with zirconyl chloride, the result was not a zirconium-phosphonate monolayer, as commonly assumed in the literature, but rather the process gives adsorbed zirconium oxide/hydroxide species and to a lower extent adsorbed zirconium phosphate and/or phosphonate. Reactions giving rise to these products were modeled in homogeneous-phase studies. Nevertheless, each of the three modified surfaces effectively immobilized phosphopeptides and phosphopeptide tags fused to an affinity protein. Unexpectedly, the zirconium oxide/hydroxide modified surface, formed by treating the amine-coated slides with POCl3/Zr(4+), afforded better immobilization of the peptides and proteins and efficient capture of their targets.

Thiolated chitosans.

PubMed

Bernkop-Schnürch, Andreas; Hornof, Margit; Guggi, Davide

2004-01-01

The derivatization of the primary amino groups of chitosan with coupling reagents bearing thiol functions leads to the formation of thiolated chitosans. So far, three types of thiolated chitosans have been generated: chitosan-cysteine conjugates, chitosan-thioglycolic acid conjugates and chitosan-4-thio-butyl-amidine conjugates. Various properties of chitosan are improved by this immobilization of thiol groups. Due to the formation of disulfide bonds with mucus glycoproteins, the mucoadhesiveness is 6--100-fold augmented (I). The permeation of paracellular markers through intestinal mucosa can be enhanced 1.6--3-fold utilizing thiolated instead of unmodified chitosan (II). Moreover, thiolated chitosans display in situ-gelling features, due to the pH-dependent formation of inter- as well as intra-molecular disulfide bonds (III). This latter process provides a strong cohesion and stability of carrier matrices being based on thiolated chitosans (IV). Consequently, thiolated chitosans can guarantee a prolonged controlled release of embedded therapeutic ingredients (V). The potential of thiolated chitosans has meanwhile also been demonstrated in vivo. A significant pharmacological efficacy of 1.3% of orally given salmon calcitonin, for instance, could be achieved utilizing thiolated chitosan as polymeric drug carrier matrix, while no effect was reached using unmodified chitosan. According to these results thiolated chitosans represent a promising new category of polymeric excipients in particular for the non-invasive administration of hydrophilic macromolecules. Further applications such as their use as scaffold materials in tissue engineering or as coating material for stents seem feasible.

Nitric Oxide-Releasing Chitosan Oligosaccharides as Antibacterial Agents

PubMed Central

Lu, Yuan; Slomberg, Danielle L.; Schoenfisch, Mark H.

2014-01-01

Secondary amine-functionalized chitosan oligosaccharides of different molecular weights (i.e., ~2500, 5000, 10000) were synthesized by grafting 2-methyl aziridine from the primary amines on chitosan oligosaccharides, followed by reaction with nitric oxide (NO) gas under basic conditions to yield N-diazeniumdiolate NO donors. The total NO storage, maximum NO flux, and half-life of the resulting NO-releasing chitosan oligosaccharides were controlled by the molar ratio of 2-methyl aziridine to primary amines (e.g., 1:1, 2:1) and the functional group surrounding the N-diazeniumdiolates (e.g., polyethylene glycol (PEG) chains), respectively. The secondary amine-modified chitosan oligosaccharides greatly increased the NO payload over existing biodegradable macromolecular NO donors. In addition, the water-solubility of the chitosan oligosaccharides enabled their penetration across the extracellular polysaccharides matrix of Pseudomonas aeruginosa biofilms and association with embedded bacteria. The effectiveness of these chitosan oligosaccharides at biofilm eradication was shown to depend on both the molecular weight and ionic characteristics. Low molecular weight and cationic chitosan oligosaccharides exhibited rapid association with bacteria throughout the entire biofilm, leading to enhanced biofilm killing. At concentrations resulting in 5-log killing of bacteria in Pseudomonas aeruginosa biofilms, the NO-releasing and control chitosan oligosaccharides elicited no significant cytotoxicity to mouse fibroblast L929 cells in vitro. PMID:24268196

40 CFR 721.10243 - Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis(2-chloroethyl) ester.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphonic acid, P-[2-[bis(2... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10243 Phosphonic acid, P-[2-[bis(2... to reporting. (1) The chemical substance identified as phosphonic acid, P-[2-[bis(2-hydroxyethyl...

40 CFR 721.10243 - Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis(2-chloroethyl) ester.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphonic acid, P-[2-[bis(2... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10243 Phosphonic acid, P-[2-[bis(2... to reporting. (1) The chemical substance identified as phosphonic acid, P-[2-[bis(2-hydroxyethyl...

Preparation and characterization of chitosan-natural nano hydroxyapatite-fucoidan nanocomposites for bone tissue engineering.

PubMed

Lowe, Baboucarr; Venkatesan, Jayachandran; Anil, Sukumaran; Shim, Min Suk; Kim, Se-Kwon

2016-12-01

Solid three dimensional (3D) composite scaffolds for bone tissue engineering were prepared using the freeze-drying method. The scaffolds were composed of chitosan, natural nano-hydroxyapatite (nHA) and fucoidan in the following combinations: chitosan, chitosan-fucoidan, chitosan-nHA, and chitosan-nHA-fucoidan. Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and optical microscopy (OM) were used to determine the physiochemical constituents and the morphology of the scaffolds. The addition of nHA into the chitosan-fucoidan composite scaffold reduced the water uptake and water retention. FT-IR analysis confirmed the presence of a phosphate group in the chitosan-nHA-fucoidan scaffold. This group is present because of the presence of nHA (isolated via alkaline hydrolysis from salmon fish bones). Microscopic results indicated that the dispersion of nHA and fucoidan in the chitosan matrix was uniform with a pore size of 10-400μm. The composite demonstrated a suitable micro architecture for cell growth and nutrient supplementation. This compatibility was further elucidated in vitro using periosteum-derived mesenchymal stem cells (PMSCs). The cells demonstrated high biocompatibility and excellent mineralization for the chitosan-nHA-fucoidan scaffold. We believe that a chitosan-nHA-fucoidan composite is a promising biomaterial for the scaffold that can be used for bone tissue regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

Methylene blue inhibits the asexual development of vivax malaria parasites from a region of increasing chloroquine resistance.

PubMed

Suwanarusk, Rossarin; Russell, Bruce; Ong, Alice; Sriprawat, Kanlaya; Chu, Cindy S; PyaePhyo, Aung; Malleret, Benoit; Nosten, François; Renia, Laurent

2015-01-01

Methylene blue, once discarded due to its unsettling yet mild side effects, has now found a renewed place in the pharmacopoeia of modern medicine. The continued spread of drug-resistant Plasmodium vivax and Plasmodium falciparum has also led to a recent re-examination of methylene blue's potent antimalarial properties. Here we examine the ex vivo susceptibility profile of Plasmodium spp. isolates to methylene blue; the isolates were from a region on the Thai-Myanmar border where there are increasing rates of failure when treating vivax malaria with chloroquine. To do this we used a newly developed ex vivo susceptibility assay utilizing flow cytometry and a portable flow cytometer with a near-UV laser. P. vivax (median methylene blue IC50 3.1 nM, IQR 1.7-4.3 nM) and P. falciparum (median methylene blue IC50 1.8 nM, IQR 1.6-2.3 nM) are susceptible to methylene blue treatment at physiologically relevant levels. Unfortunately, the addition of chloroquine to combination treatments with methylene blue significantly reduces the ex vivo effectiveness of this molecule. Our data support further efforts to employ methylene blue as a safe, low-cost antimalarial to treat drug-resistant malaria. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Study of Methylene Blue Ototoxicity in the Guinea Pig.

PubMed

Belhassen, Sarah; Alzahrani, Musaed; Nader, Marc-Elie; Gaboury, Louis; Saliba, Issam

2017-11-01

Methylene blue is widely used in the medical field, especially as a blue dye for staining. It is also used as a photosensitizing agent in antimicrobial photodynamic therapy, which once photoactivated is effective for the eradication of several multi-resistant bacteria. The objective of this study was to investigate the ototoxic potential of methylene blue and precise its use in otology. It was a prospective animal study performed on guinea pigs in our tertiary medical center. We divided the animals into two groups: an experimental group and a control group, who underwent a series of three intratympanic (IT) injections. In the control group (n = 10), they received injections of gentamicin in one ear (positive control) and normal saline in the contralateral ear (negative control). The experimental group (n = 10) received injections of methylene blue in one ear, compared to injections of normal saline in the contralateral ear. We conducted auditory-evoked brainstem response (ABR) before and 1 week after the injection series. Once this is completed, the cochlea was dissected and caspase-3 was analyzed by immunohistochemistry. The mean difference of hearing loss in the methylene blue group compared to normal saline was 1.50 dB, and it was not shown to be statistically significant (P = 0.688). For the positive control group, which received IT injections of gentamicin, the mean threshold of hearing loss difference for all the frequencies combined was 66.25 dB (P < 0.001). Furthermore, uptake of caspase-3 by immunohistochemistry (apoptotic marker) was negative in our group, which received injections of methylene blue. In light of our results, IT injections of methylene blue did not demonstrate an ototoxic potential. We recommend further studies to precise its use in the otologic field.

Study of Methylene Blue Ototoxicity in the Guinea Pig

PubMed Central

Belhassen, Sarah; Alzahrani, Musaed; Nader, Marc-Elie; Gaboury, Louis; Saliba, Issam

2017-01-01

Background Methylene blue is widely used in the medical field, especially as a blue dye for staining. It is also used as a photosensitizing agent in antimicrobial photodynamic therapy, which once photoactivated is effective for the eradication of several multi-resistant bacteria. The objective of this study was to investigate the ototoxic potential of methylene blue and precise its use in otology. Methods It was a prospective animal study performed on guinea pigs in our tertiary medical center. We divided the animals into two groups: an experimental group and a control group, who underwent a series of three intratympanic (IT) injections. In the control group (n = 10), they received injections of gentamicin in one ear (positive control) and normal saline in the contralateral ear (negative control). The experimental group (n = 10) received injections of methylene blue in one ear, compared to injections of normal saline in the contralateral ear. We conducted auditory-evoked brainstem response (ABR) before and 1 week after the injection series. Once this is completed, the cochlea was dissected and caspase-3 was analyzed by immunohistochemistry. Results The mean difference of hearing loss in the methylene blue group compared to normal saline was 1.50 dB, and it was not shown to be statistically significant (P = 0.688). For the positive control group, which received IT injections of gentamicin, the mean threshold of hearing loss difference for all the frequencies combined was 66.25 dB (P < 0.001). Furthermore, uptake of caspase-3 by immunohistochemistry (apoptotic marker) was negative in our group, which received injections of methylene blue. Conclusion In light of our results, IT injections of methylene blue did not demonstrate an ototoxic potential. We recommend further studies to precise its use in the otologic field. PMID:29038666

Perfluoroalkyl phosphonic and phosphinic acids as proton conductors for anhydrous proton-exchange membranes.

PubMed

Herath, Mahesha B; Creager, Stephen E; Kitaygorodskiy, Alex; DesMarteau, Darryl D

2010-09-10

A study of proton-transport rates and mechanisms under anhydrous conditions using a series of acid model compounds, analogous to comb-branch perfluorinated ionomers functionalized with phosphonic, phosphinic, sulfonic, and carboxylic acid protogenic groups, is reported. Model compounds are characterized with respect to proton conductivity, viscosity, proton, and anion (conjugate base) self-diffusion coefficients, and Hammett acidity. The highest conductivities, and also the highest viscosities, are observed for the phosphonic and phosphinic acid model compounds. Arrhenius analysis of conductivity and viscosity for these two acids reveals much lower activation energies for ion transport than for viscous flow. Additionally, the proton self-diffusion coefficients are much higher than the conjugate-base self-diffusion coefficients for these two acids. Taken together, these data suggest that anhydrous proton transport in the phosphonic and phosphinic acid model compounds occurs primarily by a structure-diffusion, hopping-based mechanism rather than a vehicle mechanism. Further analysis of ionic conductivity and ion self-diffusion rates by using the Nernst-Einstein equation reveals that the phosphonic and phosphinic acid model compounds are relatively highly dissociated even under anhydrous conditions. In contrast, sulfonic and carboxylic acid-based systems exhibit relatively low degrees of dissociation under anhydrous conditions. These findings suggest that fluoroalkyl phosphonic and phosphinic acids are good candidates for further development as anhydrous, high-temperature proton conductors.

Synthesis and characterization of low-toxicity N-caprinoyl-N-trimethyl chitosan as self-assembled micelles carriers for osthole

PubMed Central

Hu, Xiao-juan; Liu, Yang; Zhou, Xiao-feng; Zhu, Qiao-ling; Bei, Yong-yan; You, Ben-gang; Zhang, Chun-ge; Chen, Wei-liang; Wang, Zhou-li; Zhu, Ai-jun; Zhang, Xue-nong; Fan, Yu-jiang

2013-01-01

Novel amphiphilic chitosan derivatives (N-caprinoyl-N-trimethyl chitosan [CA-TMC]) were synthesized by grafting the hydrophobic moiety caprinoyl (CA) and hydrophilic moiety trimethyl chitosan to prepare carriers with good compatibility for poorly soluble drugs. Based on self-assembly, CA-TMC can form micelles with sizes ranging from 136 nm to 212 nm. The critical aggregation concentration increased from 0.6 mg • L−1 to 88 mg • L−1 with decrease in the degree of CA substitution. Osthole (OST) could be easily encapsulated into the CA-TMC micelles. The highest entrapment efficiency and drug loading of OST-loaded CA-TMC micelles(OST/CA-TMC) were 79.1% and 19.1%, respectively. The antitumor efficacy results show that OST/CA-TMC micelles have significant antitumor activity on Hela and MCF-7 cells, with a 50% of cell growth inhibition (IC50) of 35.8 and 46.7 μg. mL−1, respectively. Cell apoptosis was the main effect on cell death of Hela and MCF-7 cells after OST administration. The blank micelles did not affect apoptosis or cell death of Hela and MCF-7 cells. The fluorescence imaging results indicated that OST/CA-TMC micelles could be easily uptaken by Hela and MCF-7 cells and could localize in the cell nuclei. These findings suggest that CA-TMC micelles are promising carriers for OST delivery in cancer therapy. PMID:24106424

Removal of phosphonates from industrial wastewater with UV/FeII, Fenton and UV/Fenton treatment.

PubMed

Rott, Eduard; Minke, Ralf; Bali, Ulusoy; Steinmetz, Heidrun

2017-10-01

Phosphonates are an important group of phosphorus-containing compounds due to their increasing industrial use and possible eutrophication potential. This study involves investigations into the methods UV/Fe II , Fenton and UV/Fenton for their removal from a pure water matrix and industrial wastewaters. It could be shown that the degradability of phosphonates by UV/Fe II (6 kWh/m 3 ) in pure water crucially depended on the pH and was higher the less phosphonate groups a phosphonate contains. The UV/Fe II method is recommended in particular for the treatment of concentrates with nitrogen-free phosphonates, only little turbidity and a low content of organic compounds. Using Fenton reagent, the degradation of polyphosphonates was relatively weak in a pure water matrix (<20% transformation to o-PO 4 3- ). By means of the Photo-Fenton method (6 kWh/m 3 ), those phosphonates with the smallest numbers of phosphonate groups were easier degraded as well at pH 3.5 in a pure water matrix (o-PO 4 3- formation rates of up to 80%). Despite an incomplete transformation of organically bound phosphorus to o-PO 4 3- with Fenton reagent in an organically highly polluted wastewater (max. 15%), an almost total removal of the total P occurred. The most efficient total P elimination rates were achieved in accordance with the following Fenton implementation: reaction → sludge separation (acidic) → neutralization of the supernatant → sludge separation (neutral). Accordingly, a neutralization directly after the reaction phase led to a lower total P removal extent. Copyright © 2017 Elsevier Ltd. All rights reserved.

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphonic acid, p-octyl-, lanthanum... New Uses for Specific Chemical Substances § 721.10370 Phosphonic acid, p-octyl-, lanthanum (3+) salt... substance identified as phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS No. 1186211...

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphonic acid, p-octyl-, lanthanum... New Uses for Specific Chemical Substances § 721.10370 Phosphonic acid, p-octyl-, lanthanum (3+) salt... substance identified as phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS No. 1186211...

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphonic acid, p-octyl-, lanthanum... New Uses for Specific Chemical Substances § 721.10370 Phosphonic acid, p-octyl-, lanthanum (3+) salt... substance identified as phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS No. 1186211...

N,N'-Bis((6-methoxylpyridin-2-yl)methylene)-p-phenylenediimine based d(10) transition metal complexes and their utilization in co-sensitized solar cells.

PubMed

Wei, Liguo; Yang, Yulin; Fan, Ruiqing; Na, Yong; Wang, Ping; Dong, Yuwei; Yang, Bin; Cao, Wenwu

2014-08-07

N,N'-Bis((6-methoxylpyridin-2-yl)methylene)-p-phenylenediimine based four-coordinated d(10) transition metal complexes (named ML, M = Zn, Cd, Hg) were synthesized and employed as co-sensitizers and co-adsorbents in combination with a ruthenium complex N719 in dye sensitized solar cells. After co-sensitization, not only the incident-photon-to-current conversion efficiency is enhanced but also the dark current is reduced. A short circuit current density of 14.46 mA cm(-2), an open circuit voltage of 0.74 V and a fill factor of 0.62 corresponding to an overall conversion efficiency of 6.65% under AM 1.5 G solar irradiation were achieved when ZnL was used as a co-sensitizer, which are much higher than that for DSSCs only sensitized by N719 (5.22%) under the same conditions. The improvement in efficiency is attributed to the fact that N,N'-bis((6-methoxylpyridin-2-yl)methylene)-p-phenylenediimine coordinated complexes overcome the deficiency of N719 absorption in the low wavelength region of the visible spectrum, prevent its aggregation, offset competitive visible light absorption of I3(-) and reduce charge recombination due to formation of an effective cover layer of the dye molecules on the TiO2 surface. As a result, the synthesized complexes are promising candidates as co-adsorbents and co-sensitizers for highly efficient DSSCs.

Nerve transection repair using laser-activated chitosan in a rat model.

PubMed

Bhatt, Neel K; Khan, Taleef R; Mejias, Christopher; Paniello, Randal C

2017-08-01

Cranial nerve transection during head and neck surgery is conventionally repaired with microsuture. Previous studies have demonstrated recovery with laser nerve welding (LNW), a novel alternative to microsuture. LNW has been reported to have poorer tensile strength, however. Laser-activated chitosan, an adhesive biopolymer, may promote nerve recovery while enhancing the tensile strength of the repair. Using a rat posterior tibial nerve injury model, we compared four different methods of nerve repair in this pilot study. Animal study. Animals underwent unilateral posterior tibial nerve transection. The injury was repaired by potassium titanyl phosphate (KTP) laser alone (n = 20), KTP + chitosan (n = 12), microsuture + chitosan (n = 12), and chitosan alone (n = 14). Weekly walking tracks were conducted to measure functional recovery (FR). Tensile strength (TS) was measured at 6 weeks. At 6 weeks, KTP laser alone had the best recovery (FR = 93.4% ± 8.3%). Microsuture + chitosan, KTP + chitosan, and chitosan alone all showed good FR (87.4% ± 13.5%, 84.6% ± 13.0%, and 84.1% ± 10.0%, respectively). One-way analysis of variance was performed (F(3,56) = 2.6, P = .061). A TS threshold of 3.8 N was selected as a control mean recovery. Three groups-KTP alone, KTP + chitosan, and microsuture + chitosan-were found to meet threshold 60% (95% confidence interval [CI]: 23.1%-88.3%), 75% (95% CI: 46.8%-91.1%), and 100% (95% CI: 75.8%-100.0%), respectively. In the posterior tibial nerve model, all repair methods promoted nerve recovery. Laser-activated chitosan as a biopolymer anchor provided good TS and appears to be a novel alternative to microsuture. This repair method may have surgical utility following cranial nerve injury during head and neck surgery. NA Laryngoscope, 127:E253-E257, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

21 CFR 173.255 - Methylene chloride.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methylene chloride. 173.255 Section 173.255 Food... Related Substances § 173.255 Methylene chloride. Methylene chloride may be present in food under the... label of the hops extract identifies the presence of the methylene chloride and provides for the use of...

Antimicrobial Activity of Chitosan Derivatives Containing N-Quaternized Moieties in Its Backbone: A Review

PubMed Central

Martins, Alessandro F.; Facchi, Suelen P.; Follmann, Heveline D. M.; Pereira, Antonio G. B.; Rubira, Adley F.; Muniz, Edvani C.

2014-01-01

Chitosan, which is derived from a deacetylation reaction of chitin, has attractive antimicrobial activity. However, chitosan applications as a biocide are only effective in acidic medium due to its low solubility in neutral and basic conditions. Also, the positive charges carried by the protonated amine groups of chitosan (in acidic conditions) that are the driving force for its solubilization are also associated with its antimicrobial activity. Therefore, chemical modifications of chitosan are required to enhance its solubility and broaden the spectrum of its applications, including as biocide. Quaternization on the nitrogen atom of chitosan is the most used route to render water-soluble chitosan-derivatives, especially at physiological pH conditions. Recent reports in the literature demonstrate that such chitosan-derivatives present excellent antimicrobial activity due to permanent positive charge on nitrogen atoms side-bonded to the polymer backbone. This review presents some relevant work regarding the use of quaternized chitosan-derivatives obtained by different synthetic paths in applications as antimicrobial agents. PMID:25402643

Antimicrobial coating of modified chitosan onto cotton fabrics

NASA Astrophysics Data System (ADS)

Cheng, Xiaoli; Ma, Kaikai; Li, Rong; Ren, Xuehong; Huang, T. S.

2014-08-01

Chitosan has been applied as an antibacterial agent to provide biocidal function for textiles but has limitations of application condition and durability. In this study, a new N-halamine chitosan derivative was synthesized by introducing N-halamine hydantoin precursor. The synthesized chitosan derivative 1-Hydroxymethyl-5,5-dimethylhydantoin chitosan (chitosan-HDH) was coated onto cotton fabric with 1,2,3,4-butanetetracarboxylic acid (BTCA) as a crosslinking agent. The coatings were characterized and confirmed by FT-IR and SEM. The treated cotton fabrics can be rendered excellent antimicrobial activity upon exposure to dilute household bleach. The chlorinated coated swatches can inactivate 100% of the Staphylococcus aureus and E. coli O157:H7 with a contact time of 5 min. Almost all the lost chlorine after a month of storage could be recharged upon rechlorination. The crease recovery property of the treated swatches improved while the breaking strength decreased compared with uncoated cotton.

Intermediate temperature proton conductors for PEM fuel cells based on phosphonic acid as protogenic group: a progress report.

PubMed

Steininger, H; Schuster, M; Kreuer, K D; Kaltbeitzel, A; Bingöl, B; Meyer, W H; Schauff, S; Brunklaus, G; Maier, J; Spiess, H W

2007-04-21

The melting behaviour and transport properties of straight chain alkanes mono- and difunctionalized with phosphonic acid groups have been investigated as a function of their length. The increase of melting temperature and decrease of proton conductivity with increasing chain length is suggested to be the consequence of an increasing ordering of the alkane segments which constrains the free aggregation of the phosphonic acid groups. However, the proton mobility is reduced to a greater extent than the proton diffusion coefficient indicating an increasing cooperativity of proton transport with increasing length of the alkane segment. The results clearly indicate that the "spacer concept", which had been proven successful in the optimization of the proton conductivity of heterocycle based systems, fails in the case of phosphonic acid functionalized polymers. Instead, a very high concentration of phosphonic acid functional groups forming "bulky" hydrogen bonded aggregates is suggested to be essential for obtaining very high proton conductivity. Aggregation is also suggested to reduce condensation reactions generally observed in phosphonic acid containing systems. On the basis of this understanding, the proton conductivities of poly(vinyl phosphonic acid) and poly(meta-phenylene phosphonic acid) are discussed. Though both polymers exhibit a substantial concentration of phosphonic acid groups, aggregation seems to be constrained to such an extent that intrinsic proton conductivity is limited to values below sigma = 10(-3) S cm(-1) at T = 150 degrees C. The results suggest that different immobilization concepts have to be developed in order to minimize the conductivity reduction compared to the very high intrinsic proton conductivity of neat phosphonic acid under quasi dry conditions. In the presence of high water activities, however, (as usually present in PEM fuel cells) the very high ion exchange capacities (IEC) possible for phosphonic acid functionalized ionomers (IEC

Phosphonic Acids on an Atomically Defined Oxide Surface: The Binding Motif Changes with Surface Coverage.

PubMed

Schuschke, Christian; Schwarz, Matthias; Hohner, Chantal; Silva, Thais N; Fromm, Lukas; Döpper, Tibor; Görling, Andreas; Libuda, Jörg

2018-04-19

We have studied the anchoring mechanism of a phosphonic acid on an atomically defined oxide surface. Using time-resolved infrared reflection absorption spectroscopy, we investigated the reaction of deuterated phenylphosphonic acid (DPPA, C 6 H 5 PO 3 D 2 ) with an atomically defined Co 3 O 4 (111) surface in situ during film growth by physical vapor deposition. We show that the binding motif of the phosphonate anchor group changes as a function of coverage. At low coverage, DPPA binds in the form of a chelating tridentate phosphonate, while a transition to a chelating bidentate occurs close to monolayer saturation coverage. However, the coverage-dependent change in the binding motif is not associated with a major change of the molecular orientation, suggesting that the rigid phosphonate linker always maintains the DPPA in a strongly tilted orientation irrespective of the surface coverage.

Octa- and hexametallic iron(III)-potassium phosphonate cages.

PubMed

Gopal, Kandasamy; Tuna, Floriana; Winpenny, Richard E P

2011-12-07

Two new iron(III)-potassium phosphonate cage complexes with {K(2)Fe(6)} and {K(2)Fe(4)} cores are reported. Magnetic studies reveal antiferromagnetic interactions between the Fe(III) centres occur in these cages.

Impact of salt form and molecular weight of chitosan on swelling and drug release from chitosan matrix tablets.

PubMed

Huanbutta, Kampanart; Cheewatanakornkool, Kamonrak; Terada, Katsuhide; Nunthanid, Jurairat; Sriamornsak, Pornsak

2013-08-14

Magnetic resonance imaging (MRI) and gravimetric techniques were used to assess swelling and erosion behaviors of hydrophilic matrix tablets made of chitosan. The impact of salt form, molecular weight (MW) and dissolution medium on swelling behavior and drug (theophylline) release was studied. The matrix tablets made of chitosan glycolate (CGY) showed the greatest swelling in both acid and neutral media, compared to chitosan aspartate, chitosan glutamate and chitosan lactate. MRI illustrated that swelling region of CGY in both media was not different in the first 100 min but glassy region (dry core) in 0.1N HCl was less than in pH 6.8 buffer. The tablets prepared from chitosan with high MW swelled greater than those of low MW. Moreover, CGY can delay drug release in the acid condition due to thick swollen gel and low erosion rate. Therefore, CGY may be suitably applied as sustained drug release polymer or enteric coating material. Copyright © 2013 Elsevier Ltd. All rights reserved.

Amphiphilic chitosan derivatives as carrier agents for rotenone

NASA Astrophysics Data System (ADS)

Kamari, Azlan; Aljafree, Nurul Farhana Ahmad

2017-08-01

In the present study, the feasibility of amphiphilic chitosan derivatives, namely oleoyl carboxymethyl chitosan (OCMCs), N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) and deoxycholic acid carboxymethyl chitosan (DACMCs) as carrier agents for rotenone in water-insoluble pesticide formulations was investigated. Fourier Transform Infrared (FTIR) Spectrometer, CHN-O Elemental Analyser (CHN-O) and Transmission Electron Microscope (TEM) were used to characterise amphiphilic chitosan derivatives. The critical micelle concentration (CMC) of amphiphilic chitosan derivatives was determined using a Fluorescence Spectrometer. A High Performance Liquid Chromatography (HPLC) was used to determine the ability of OCMCs, DCMCs and DACMCs to load and release rotenone in an in vitro system. Based on TEM analysis, results have shown that amphiphilic chitosan derivatives formed self-assembly and exhibited spherical shape. The CMC values determined for OCMCs, DCMCs and DACMCs were 0.093, 0.098 and 0.468 mg/mL, respectively. The encapsulation efficiency (EE) values for the materials were more than 97.0%, meanwhile the loading capacity (LC) values were greater than 0.90%. OCMCs, DCMCs and DACMCs micelles exhibited an excellent ability to control the release of rotenone, of which 90.0% of rotenone was released within 40 to 52 h. In conclusion, OCMCs, DCMCs and DACMCs possess several key features to act as effective carrier agents for rotenone. Overall, amphiphilic chitosan derivatives produced in this study were successfully increased the solubility of rotenone by 49.0 times higher than free rotenone.

Synthesis and characterization of chitosan alkyl urea.

PubMed

Wang, Jing; Jiang, Ji-Zhou; Chen, Wei; Bai, Zheng-Wu

2016-07-10

Chitosan is a versatile material employed for various purposes in many fields including the development of chiral stationary phases for enantioseparation. Chitosan alkyl urea is a kind of intermediate used to prepare enantioseparation materials. In order to synthesize the intermediates, in the present work, a new way to prepare chitosan alkyl urea has been established: chitosan was first reacted with methyl chloroformate yielding N-methoxyformylated chitosan, which was then converted to chitosan alkyl urea through amine-ester exchange reaction. With a large excess of methyl chloroformate and primary amine of low stereohindrance, the amino group in chitosan could be almost completely converted to ureido group. The as-prepared chitosan alkyl urea derivatives were characterized by IR, (1)H NMR, (13)C NMR,(1)H-(1)H COSY and (1)H-(13)C HSQC NMR spectra. The chemical shifts of hydrogen and carbon atoms of glucose unit were assigned. It was found that the degree of substitution was obviously lower if cyclopropyl amine, aniline, tert-butyl amine and diethyl amine were used as reactants for the amine-ester exchange reaction. The reason was explained with the aid of theoretical calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methylene blue-aided cholangioscopy in patients with biliary strictures: feasibility and outcome analysis.

PubMed

Hoffman, A; Kiesslich, R; Bittinger, F; Galle, P R; Neurath, M F

2008-07-01

Chromoendoscopy using methylene blue is employed in the gastrointestinal tract to delineate neoplastic lesions. We tested the value of chromoendoscopy during choledochoscopy for characterization of local inflammation, neoplasias, and other alterations in patients with biliary strictures. Patients with suspected biliary lesions were scheduled for endoscopic retrograde cholangiography with subsequent cholangioscopy. After initial inspection of the bile duct, 15 ml methylene blue (0.1 %) was administered via the working channel of the cholangioscope. Newly appearing circumscribed or unstained lesions were judged according to their macroscopic type and staining features. Methylene-blue-aided diagnosis was compared with either clinical follow-up of the patients or, in some cases, with the results of targeted biopsies. A total of 55 patients [biliary stenosis/cholestasis of unknown origin (n = 24), stenosis after orthotopic liver transplantation (n = 11), primary sclerosing cholangitis (n = 20)] were included. Methylene blue unmasked subtle mucosal changes and permitted macroscopic characterization of circumscribed lesions. Characteristic surface staining patterns were seen in chronic inflammation, dysplasia, and ischemic-type biliary lesions. Nondysplastic mucosa appeared homogeneously stained, whereas scarred strictures showed a weak uptake of methylene blue. In this prospective feasibility study, methylene-blue-aided cholangioscopy was used for the first time to define different staining patterns of the bile duct. The differences in staining patterns identified normal, dysplastic, and inflamed mucosa of the bile duct, as was proved by follow-up or, in some cases, histology. Whereas homogeneous staining predicted the presence of normal mucosa, absence of staining of circumscribed lesions, or diffused staining of such lesions, represented neoplastic changes or inflammation.

Supramolecular metallogels with complex of phosphonate substituted carbazole derivative and aluminum(III) ion as gelator.

PubMed

Ding, Zicheng; Chen, Bo; Ding, Junqiao; Wang, Lixiang; Han, Yanchun

2014-07-01

Supramolecular metallogels can be gained from the phosphonate substituted 4,4'-bis(N-carbazolyl)biphenyl (PCBP) in the presence of aluminum chloride in alcohols, which can donate oxygen to aid proton transfer in the aluminum organophosphorus complexes. Inside the metallogels, three-dimensional fiber networks with nanofibers entangling and intersecting with each other inside are formed. The nanofibers show layered structures with a period thickness of 0.82 nm. As the content of aluminum(III) increases, the size of the fibers becomes smaller and the fibers pack more densely. It makes the transparent gel become turbid but nevertheless improves the stability of the metallogels. NMR, FT-IR and fluorescence spectroscopy show that the coordination interactions between the phosphonate groups of PCBP molecules and aluminum(III) ions as well as the π-π interactions among PCBP molecules are involved during the gel formation process. Copyright © 2014 Elsevier Inc. All rights reserved.

Developmental Toxicity of Perfluorinated Phosphonic Acids in Mice

EPA Science Inventory

Perfluorinated phosphonic acids (PFPAs) are a third member of the perfluoroalkyl acid (PFAA) family, and are structurally similar to the perfluoroalkyl sulfonates and perfluoroalkyl carboxylates. PFPAs are used primarily as a surfactant defoaming agent in pesticide production. Re...

Green synthesis approach: extraction of chitosan from fungus mycelia.

PubMed

Dhillon, Gurpreet Singh; Kaur, Surinder; Brar, Satinder Kaur; Verma, Mausam

2013-12-01

Chitosan, copolymer of glucosamine and N-acetyl glucosamine is mainly derived from chitin, which is present in cell walls of crustaceans and some other microorganisms, such as fungi. Chitosan is emerging as an important biopolymer having a broad range of applications in different fields. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal sources. The methods used for extraction of chitosan are laden with many disadvantages. Alternative options of producing chitosan from fungal biomass exist, in fact with superior physico-chemical properties. Researchers around the globe are attempting to commercialize chitosan production and extraction from fungal sources. Chitosan extracted from fungal sources has the potential to completely replace crustacean-derived chitosan. In this context, the present review discusses the potential of fungal biomass resulting from various biotechnological industries or grown on negative/low cost agricultural and industrial wastes and their by-products as an inexpensive source of chitosan. Biologically derived fungal chitosan offers promising advantages over the chitosan obtained from crustacean shells with respect to different physico-chemical attributes. The different aspects of fungal chitosan extraction methods and various parameters having an effect on the yield of chitosan are discussed in detail. This review also deals with essential attributes of chitosan for high value-added applications in different fields.

Seasonal Expression of the Picocyanobacterial Phosphonate Transporter Gene phnD in the Sargasso Sea

PubMed Central

Ilikchyan, Irina N.; McKay, Robert Michael L.; Kutovaya, Olga A.; Condon, Rob; Bullerjahn, George S.

2010-01-01

In phosphorus-limited marine environments, picocyanobacteria (Synechococcus and Prochlorococcus spp.) can hydrolyze naturally occurring phosphonates as a P source. Utilization of 2-aminoethylphosphonate (2-AEP) is dependent on expression of the phn genes, encoding functions required for uptake, and C–P bond cleavage. Prior work has indicated that expression of picocyanobacterial phnD, encoding the phosphonate binding protein of the phosphonate ABC transporter, is a proxy for the assimilation of phosphonates in natural assemblages of Synechococcus spp. and Prochlorococcus spp (Ilikchyan et al., 2009). In this study, we expand this work to assess seasonal phnD expression in the Sargasso Sea. By RT-PCR, our data confirm that phnD expression is constitutive for the Prochlorococcus spp. detected, but in Synechococcus spp. phnD transcription follows patterns of phosphorus availability in the mixed layer. Specifically, our data suggest that phnD is repressed in the spring when P is bioavailable following deep winter mixing. In the fall, phnD expression follows a depth-dependent pattern reflecting depleted P at the surface following summertime drawdown, and elevated P at depth. PMID:21687717

Peptide-decorated chitosan derivatives enhance fibroblast adhesion and proliferation in wound healing.

PubMed

Patrulea, V; Hirt-Burri, N; Jeannerat, A; Applegate, L A; Ostafe, V; Jordan, O; Borchard, G

2016-05-20

RGD peptide sequences are known to regulate cellular activities by interacting with α5β1, αvβ5 and αvβ3 integrin, which contributes to the wound healing process. In this study, RGDC peptide was immobilized onto chitosan derivative 1,6-diaminohexane-O-carboxymethyl-N,N,N-trimethyl chitosan (DAH-CMTMC) to display RGDC-promoting adhesion for enhanced wound healing. The efficiency of N-methylation, O-carboxymethylation and spacer grafting was quantitatively and qualitatively analyzed by (1)H NMR and FTIR, yielding 0.38 degree of substitution for N-methylation and >0.85 for O-carboxymethylation. The glass transition temperatures for chitosan derivatives were also studied. Peptide immobilization was achieved through sulfhydryl groups using sulfosuccinimidyl (4-iodoacetyl)amino-benzoate (sulfo-SIAB method). RGDC immobilized peptide onto DAH-CMTMC was found to be about 15.3 μg/mg of chitosan derivative by amino acid analysis (AAA). The significant increase of human dermal fibroblast (HDF) viability in vitro over 7 days suggests that RGDC-functionalized chitosan may lead to enhanced wound healing (viability >140%). Moreover, bio-adhesion and proliferation assays confirmed that coatings of RGDC-functionalized chitosan derivatives exhibit in vitro wound healing properties by enhancing fibroblast proliferation and adhesion. These results showed that RGDC peptide-functionalized chitosan provides an optimal environment for fibroblast adhesion and proliferation. Copyright © 2016 Elsevier Ltd. All rights reserved.

An overview of chitin or chitosan/nano ceramic composite scaffolds for bone tissue engineering.

PubMed

Deepthi, S; Venkatesan, J; Kim, Se-Kwon; Bumgardner, Joel D; Jayakumar, R

2016-12-01

Chitin and chitosan based nanocomposite scaffolds have been widely used for bone tissue engineering. These chitin and chitosan based scaffolds were reinforced with nanocomponents viz Hydroxyapatite (HAp), Bioglass ceramic (BGC), Silicon dioxide (SiO 2 ), Titanium dioxide (TiO 2 ) and Zirconium oxide (ZrO 2 ) to develop nanocomposite scaffolds. Plenty of works have been reported on the applications and characteristics of the nanoceramic composites however, compiling the work done in this field and presenting it in a single article is a thrust area. This review is written with an aim to fill this gap and focus on the preparations and applications of chitin or chitosan/nHAp, chitin or chitosan/nBGC, chitin or chitosan/nSiO 2 , chitin or chitosan/nTiO 2 and chitin or chitosan/nZrO 2 in the field of bone tissue engineering in detail. Many reports so far exemplify the importance of ceramics in bone regeneration. The effect of nanoceramics over native ceramics in developing composites, its role in osteogenesis etc. are the gist of this review. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 173.255 - Methylene chloride.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Methylene chloride. 173.255 Section 173.255 Food... Solvents, Lubricants, Release Agents and Related Substances § 173.255 Methylene chloride. Methylene chloride may be present in food under the following conditions: (a) In spice oleoresins as a residue from...

21 CFR 173.255 - Methylene chloride.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methylene chloride. 173.255 Section 173.255 Food... Solvents, Lubricants, Release Agents and Related Substances § 173.255 Methylene chloride. Methylene chloride may be present in food under the following conditions: (a) In spice oleoresins as a residue from...

The supramolecular architecture of tris(naphthalene-1,5-diaminium) bis(5-aminonaphthalen-1-aminium) octakis[hydrogen (5-carboxypyridin-3-yl)phosphonate].

PubMed

Wilk, Magdalena; Janczak, Jan; Videnova-Adrabinska, Veneta

2012-09-01

The asymmetric unit of the title compound, 3C(10)H(12)N(2)(2+)·2C(10)H(11)N(2)(+)·8C(6)H(5)NO(5)P(-), contains one and a half naphthalene-1,5-diaminium cations, in which the half-molecule has inversion symmetry, one 5-aminonaphthalen-1-aminium cation and four hydrogen (5-carboxypyridin-3-yl)phosphonate anions. The crystal structure is layered and consists of hydrogen-bonded anionic monolayers between which the cations are arranged. The acid monoanions are organized into one-dimensional chains along the [101] direction via hydrogen bonds established between the phosphonate sites. (C)O-H···N(py) hydrogen bonds (py is pyridine) crosslink the chains to form an undulating (010) monolayer. The cations serve both to balance the charge of the anionic network and to connect neighbouring layers via multiple hydrogen bonds to form a three-dimensional supramolecular architecture.

Phosphonic acid functionalization of nanostructured Ni-W coatings on steel

NASA Astrophysics Data System (ADS)

Orrillo, P. A.; Ribotta, S. B.; Gassa, L. M.; Benítez, G.; Salvarezza, R. C.; Vela, M. E.

2018-03-01

The functionalization of nanocrystalline Ni-W coatings, formed by galvanostatic pulsed electrodeposition on steel, by thermal treatment of octadecylphosphonic acid self-assembled on the oxidized alloy surface is studied by Raman spectroscopy, contact angle measurements, X-ray photoelectron spectroscopy, AFM and electrochemical techniques. Results show that this procedure preserves the surface topography and the optimum mechanical properties of the alloy. More importantly, it turns the alloy surface highly hydrophobic and markedly improves its corrosion resistance, in particular to pitting corrosion in aggressive solutions containing chloride anions. The ability of the phosphonate layer to improve surface properties arises from the barrier properties introduced by the hydrocarbon chains and the strong bonds between the phosphonate head and the underlying surface oxides.

Functionalization of chitosan by click chemistry

NASA Astrophysics Data System (ADS)

Cheaburu-Yilmaz, Catalina Natalia; Karavana, Sinem Yaprak; Yilmaz, Onur

2017-12-01

Chitosan modification represents a challenge nowadays. The variety of compounds which can be obtained with various architectures and different functionalities made it attractive to be used in fields like pharmacy and material science. Presents study deals with the chemical modification of chitosan by using click chemistry technique. The study adopted the approach of clicking azidated chitosan with a synthesized alkyne terminated polymer i.e. poly N isopropylacrylamide with thermoresponsive properties. Structures were confirmed by the FT-IR and HNMR spectra. Thermal characterization was performed showing different thermal behaviour with the chemical modification. The final synthesized graft copolymer can play important role within pharmaceutical formulations carrying drugs for topical or oral treatments.

Comparative study of chitosan and chitosan-gelatin scaffold for tissue engineering

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Dehiya, Brijnandan S.; Sindhu, Anil

2017-12-01

A number of orthopedic disorders and bone defect issues are solved by scaffold-based therapy in tissue engineering. The biocompatibility of chitosan (polysaccharide) and its similarity with glycosaminoglycan makes it a bone-grafting material. The current work focus on the synthesis of chitosan and chitosan-gelatin scaffold for hard tissue engineering. The chitosan and chitosan-gelatin scaffold have shown improved specific surface area, density, porosity, mechanical properties, biodegradability and absorption. These scaffolds can lead to the development or artificial fabrication of hard tissue alternates. The porous scaffold samples were prepared by freeze-drying method. The microstructure, mechanical and degradable properties of chitosan and chitosan-gelatin scaffolds were analyzed and results revealed that the scaffolds prepared from chitosan-gelatin can be utilized as a useful matrix for tissue engineering.

Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(caprolactone)/chitosan blends.

PubMed

Ghorbani, Fereshte Mohammad; Kaffashi, Babak; Shokrollahi, Parvin; Akhlaghi, Shahin; Hedenqvist, Mikael S

2016-02-01

The effect of hydroxyapatite nano-particles (nHA) on morphology, and rheological and thermal properties of PCL/chitosan blends was investigated. The tendency of nHA to reside in the submicron-dispersed chitosan phase is determined using SEM and AFM images. The presence of electrostatic interaction between amide sites of chitosan and ionic groups on the nHA surface was proved by FTIR. It is shown that the chitosan phase is thermodynamically more favorable for the nano-particles to reside than the PCL phase. Lack of implementation of Cox-Merz theory for this system shows that the polymer-nano-particle network is destructed by the flow. Results from dynamic rheological measurements and Zener fractional model show that the presence of nHA increases the shear moduli and relaxation time of the PCL/chitosan blends. DSC measurements showed that nHA nano-particles are responsible for the increase in melting and crystallization characteristics of the PCL/chitosan blends. Based on thermogravimetric analysis, the PCL/chitosan/nHA nano-composites exhibited a greater thermal stability compared to the nHA-free blends. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrosprayed chitosan nanoparticles: facile and efficient approach for bacterial transformation

NASA Astrophysics Data System (ADS)

Abyadeh, Morteza; Sadroddiny, Esmaeil; Ebrahimi, Ammar; Esmaeili, Fariba; Landi, Farzaneh Saeedi; Amani, Amir

2017-12-01

A rapid and efficient procedure for DNA transformation is a key prerequisite for successful cloning and genomic studies. While there are efforts to develop a facile method, so far obtained efficiencies for alternative methods have been unsatisfactory (i.e. 105-106 CFU/μg plasmid) compared with conventional method (up to 108 CFU/μg plasmid). In this work, for the first time, we prepared chitosan/pDNA nanoparticles by electrospraying methods to improve transformation process. Electrospray method was used for chitosan/pDNA nanoparticles production to investigate the non-competent bacterial transformation efficiency; besides, the effect of chitosan molecular weight, N/P ratio and nanoparticle size on non-competent bacterial transformation efficiency was evaluated too. The results showed that transformation efficiency increased with decreasing the molecular weight, N/P ratio and nanoparticles size. In addition, transformation efficiency of 1.7 × 108 CFU/μg plasmid was obtained with chitosan molecular weight, N/P ratio and nanoparticles size values of 30 kDa, 1 and 125 nm. Chitosan/pDNA electrosprayed nanoparticles were produced and the effect of molecular weight, N/P and size of nanoparticles on transformation efficiency was evaluated. In total, we present a facile and rapid method for bacterial transformation, which has comparable efficiency with the common method.

[Seven cases of parathyroidectomy for secondary hyperparathyroidism using methylene blue: suggestion for the method of methylene blue infusion].

PubMed

Kadoya, Tatsuo; Kinoshita, Yuki; Shiraishi, Munehiro; Uehara, Hirofumi; Yamamoto, Toshinori; Suetsugu, Keiko

2014-08-01

Intraoperative staining of the parathyroid glands with intravenously administered methylene blue is well described and has been demonstrated as an effective and safe method to facilitate parathyroidectomy. However, there have been several literatures of the development of postoperative neurological toxicity in patients who received methylene blue infusion during parathyroidectomy. We report the method of methylene blue infusion during parathyroidectomy at our institution. Seven adult patients who had undergone parathyroidectomy for secondary hyperparathyroidism associated with chronic renal failure were included in this study. Methylene blue was administered at a constant rate of 4 mg x kg(-1) x hr(-1) with a 1% solution just before the start of operation. The infusion was stopped after the first parathyroid gland was identified. The mean dose of methylene blue used was 2.2 +/- 0.8 mg x kg(-1). Consequently, the dose of methylene blue by this method could be decreased to less than half of the previously administered dose (6 mg x kg(-1)) at our institution. The dose of methylene blue used should be kept to the minimum required to identify the parathyroid glands in each case.

Tribology and stability of organic monolayers on CrN: a comparison among silane, phosphonate, alkene, and alkyne chemistries.

PubMed

Pujari, Sidharam P; Li, Yan; Regeling, Remco; Zuilhof, Han

2013-08-20

The fabrication of chemically and mechanically stable monolayers on the surfaces of various inorganic hard materials is crucial to the development of biomedical/electronic devices. In this Article, monolayers based on the reactivity of silane, phosphonate, 1-alkene, and 1-alkyne moieties were obtained on the hydroxyl-terminated chromium nitride surface. Their chemical stability and tribology were systematically investigated. The chemical stability of the modified CrN surfaces was tested in aqueous media at 60 °C at pH 3, 7, and 11 and monitored by static water contact angle measurements, X-ray photoelectron spectroscopy (XPS), ellipsometry, and Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS). The tribological properties of the resulting organic monolayers with different end groups (fluorinated or nonfluorinated) were studied using atomic force microscopy (AFM). It was found that the fluorinated monolayers exhibit a dramatic reduction of adhesion and friction force as well as excellent wear resistance compared to those of nonfluorinated coatings and bare CrN substrates. The combination of remarkable chemical stability and superior tribological properties makes these fluorinated monolayers promising candidates for the development of robust high-performance devices.

Phosphonated Near-Infrared Fluorophores for Biomedical Imaging of Bone**

PubMed Central

Hyun, Hoon; Wada, Hideyuki; Bao, Kai; Gravier, Julien; Yadav, Yogesh; Laramie, Matt; Henary, Maged; Frangioni, John V.

2014-01-01

The conventional method for creating targeted contrast agents is to conjugate separate targeting and fluorophore domains. In this study we report a new strategy based on incorporation of targeting moieties into the non-resonant structure of pentamethine and heptamethine indocyanines. Using the known affinity of phosphonates for bone minerals as a model system, we have synthesized two families of bifunctional molecules that target bone without the need for a traditional bisphosphonate. With peak fluorescence emission at ≈ 700 nm or ≈ 800 nm, these molecules can be used for FLARE dual-channel imaging. Longitudinal FLARE studies in mice demonstrate that phosphonated near-infrared fluorophores remain stable in bone for over 5 weeks, and histological analysis demonstrates incorporation into bone matrix. Taken together, we describe a new strategy for creating ultracompact, targeted, near-infrared fluorophores for various bioimaging applications. PMID:25139079

Reactive extraction of lactic acid with trioctylamine/methylene chloride/n-hexane

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

Han, D.H.; Hong, W.H.

The trioctylamine (TOA)/methylene chloride (MC)/n-hexane system was used as the extraction agent for the extraction of lactic acid. Curves of equilibrium and hydration were obtained at various temperatures and concentrations of TOA. A modified mass action model was proposed to interpret the equilibrium and the hydration curves. The reaction mechanism and the corresponding parameters which best represent the equilibrium data were estimated, and the concentration of water in the organic phase was predicted by inserting the parameters into the simple mathematical equation of the modified model. The concentration of MC and the change of temperature were important factors for themore » extraction and the stripping process. The stripping was performed by a simple distillation which was a combination of temperature-swing regeneration and diluent-swing regeneration. The type of inactive diluent has no influence on the stripping. The stripping efficiencies were about 70%.« less

Nitrate decontamination through functionalized chitosan in brackish water.

PubMed

Appunni, Sowmya; Rajesh, Mathur P; Prabhakar, Sivaraman

2016-08-20

N, N, N-Triethyl ammonium functionalized cross-linked chitosan beads (TEACCB) was prepared by alkylation of glutaraldehyde cross-linked chitosan beads to remove nitrate from brackish water. Physico-chemical characteristics of TEACCB were analyzed using FTIR, SEM, EDAX, TGA, DTA, BET surface area, swelling ratio and pHzpc. The maximum nitrate removal capacity of TEACCB was 2.26meq/g and is higher than other reported chitosan based adsorbents. Nitrate removal ratio in the presence and absence of common anions like chloride and sulphate demonstrated the selectively of TEACCB towards nitrate. The kinetic data of nitrate removal fitted well with the pseudo-second-order kinetic model. The thermodynamic parameters indicated that nitrate removal could be spontaneous and exothermic in nature. TEACCB was reused with 100% efficiency after regenerating with 0.05N HCl. Column study was carried out to remove nitrate from brackish water. These results are very significant to develop TEACCB based nitrate removal technology with great efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

NASA Astrophysics Data System (ADS)

Khairul, Wan M.; Daud, Adibah Izzati; Ismail, Noraznawati

2018-02-01

In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N'-(4-nitrobenzoyl) thiourea (1), N-chitosan-N'-(4-chlorobenzoyl) thiourea (2), N-chitosan-N'-(4-methylbenzoyl) thiourea (3), N-chitosan-N'-(2-iodobenzoyl) thiourea (4), and N-chitosan-N'-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activity as they were able to inhibit both Gram-positive and Gram-negative bacteria. Therefore, 1-5 showed good antibacterial activity and have high potential to be further developed as active materials in pharmaceutical interests.

Microwave-Assisted Hydrolysis of Chitosan from Shrimp Shell Waste for Glucosammine Hydrochlorid Production

NASA Astrophysics Data System (ADS)

Zaeni, Ahmad; Safitri, Endang; Fuadah, Badrotul; Nyoman Sudiana, I.

2017-05-01

Chitin is the most widespread renewable natural sources following cellulose as the main source of chitosan. Chitin is isolated from crustacean waste and shrimp shells. Chitosan is derived from chitin throuhgt demineralisation, deproteination, decolorisation and deacetylation process using chemicals such as sodium hydroxide, hydrogen chloride and acetone. Glucosamine hydrochloride (GlcN-Cl) can be produced by hydrolysis of chitosan by using hydrogen chloride. During deacetylation and hydrolysis the solution is heated by hotplate or furnace. In this paper we use microwave instead of hotplate for production chitosan and GlcN-Cl. The research investigates effect of microwaves to amount of rendemen and their property. The chitosan was characterized its moisture content, solubility, and degree of deacetylation (DDA). Whereas the glucosammine hydrochloride characterized its functional groups using FTIR and crystallization by using X-Ray Difraction (XRD). The experimental results show that the use of microwave energy on deacetilation of chitosan and hydrolisis processes can decrease time consuming and reactant concentration during production. the DDA value obtained was very high from 70 to 85%. The results also show that microwaves meet chitosan and GlcN-Cl standards.

Synthesis and properties of ApA analogues with shortened phosphonate internucleotide linkage.

PubMed

Králíková, Sárka; Buděšínský, Miloš; Barvík, Ivan; Masojídková, Milena; Točík, Zdeněk; Rosenberg, Ivan

2011-01-01

A complete series of the 2 '-5 ' and 3 '-5 ' regioisomeric types of r(ApA) and 2 '-d(ApA) analogues with the α-hydroxy-phosphonate C3 '-O-P-CH(OH)-C4 ″ internucleotide linkage, isopolar but non-isosteric with the phosphodiester one, were synthesized and their hybridization properties with polyU studied. Due to the chirality on the 5 '-carbon atom of the modified internucleotide linkage bearing phosphorus and hydroxy moieties, each regioisomeric type of ApA dimer is split into epimeric pairs. To examine the role of the 5 '-hydroxyl of the α-hydroxy-phosphonate moiety during hybridization, the appropriate r(ApA) analogues with 3 '(2 ')-O-P-CH(2)-C4 ″ linkage lacking the 5 '-hydroxyl were synthesized. Nuclear magnetic resonance (NMR) spectroscopy study on the conformation of the modified sugar-phosphate backbone, along with the hybridization measurements, revealed remarkable differences in the stability of complexes with polyU, depending on the 5 '-carbon atom configuration. Potential usefulness of the α-hydroxy-phosphonate linkage in modified oligoribonucleotides is discussed.

Synthesis, physiochemical and optical properties of chitosan based dye containing naphthalimide group.

PubMed

Kumar, Santosh; Koh, Joonseok

2013-04-15

A new biopolymer dye containing naphthalimide moiety was synthesized by reaction of N-naphthaloyl chitosan with 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazino-3-quinolinecarboxylic acid. N-naphthaloyl chitosan was synthesized by reaction of chitosan with 4-bromo-1,8-naphthalic anhydride in aqueous media by greener approach. The degree of substitution of chitosan biopolymer dye is 0.55 with a yield of 70%. The synthesized materials were characterized by using UV-vis, (1)H NMR, FTIR, and FT-Raman spectroscopy. Some physical properties and surface morphology were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Optical properties of chitosan biopolymer dye were evaluated by photoluminescence (PL) spectroscopy that showed red shift (λ(em)) peak at 442 nm and 551 nm at excitation wavelength 325 nm in comparison to chitosan. The solubility of chitosan biopolymer dye increased in most of the organic solvents. These results may provide new perspectives in biomedical applications as an optical and sensitive biosensor material. Copyright © 2013 Elsevier Ltd. All rights reserved.

Robotic laser tissue welding of sclera using chitosan films.

PubMed

Garcia, Pablo; Mines, Michael J; Bower, Kraig S; Hill, J; Menon, J; Tremblay, Eric; Smith, Benjamin

2009-01-01

To demonstrate the feasibility of scleral wound closure using a novel adhesive made of chitosan film. Five-millimeter scleral lacerations were created in enucleated pig eyes. Casted chitosan films were sized to 7x7 mm patches. Lacerations were sealed with chitosan film alone (7 eyes) or chitosan film followed by laser irradiation using a near infrared laser (1,455 nm) at 350 mW for 6 minutes (7 eyes). Seven eyes were closed with 9-0 nylon suture for comparison (7 eyes). Outcome measures included watertight closure, closure time, and leak pressure. Leak pressure was measured with a pressure transducer attached to tubing continuously monitored intraocular pressure during saline infusion. Watertight closure testing was performed immediately following closure (n = 3 per group) and after 24 hours (n = 3 per group). One eye in each group was fixed in formalin for histology. All wounds were watertight for each closure method. Mean closure time with unlasered chitosan film was 2.24 minutes (range 1.80-3.26, 7 eyes) with a mean leak pressure of 303 mm Hg (range 217-364, 3 eyes). Mean closure time with lasered chitosan was 12.47 minutes (range 11.45-14.15, 7 eyes) with a mean leak pressure of 454.7 mm Hg (range 152-721, 3 eyes). Suture closure required a mean of 4.83 minutes (range 4.03-7.30, 7 eyes) and resulted in a mean leak pressure of 570.3 mm Hg (range 460-646, 3 eyes). Both lasered and unlasered chitosan eyes remained watertight after 24 hours. Histology revealed minimal laser tissue damage in lasered eyes. In this preliminary study chitosan film successfully closed scleral lacerations with and without the application of laser energy. While laser appears to strengthen the closure, it significantly increases the closure time. Chitosan based adhesives hold promise as a scleral wound closure technique.

Comperative study of catalase immobilization on chitosan, magnetic chitosan and chitosan-clay composite beads.

PubMed

Başak, Esra; Aydemir, Tülin; Dinçer, Ayşe; Becerik, Seda Çınar

2013-12-01

Catalase was immobilized on chitosan and modified chitosan. Studies were carried out on free-immobilized catalase concerning the determination of optimum temperature, pH, thermal, storage stability, reusability, and kinetic parameters. Optimum temperature and pH for free catalase and catalase immobilized were found as 35°C and 7.0, respectively. After 100 times of repeated tests, the immobilized catalases on chitosan-clay and magnetic chitosan maintain over 50% and 60% of the original activity, respectively. The ease of catalase immobilization on low-cost matrices and good stability upon immobilization in the present study make it a suitable product for further use in the food industry.

Environmentally friendly surface modification of silk fiber: Chitosan grafting and dyeing

NASA Astrophysics Data System (ADS)

Davarpanah, Saideh; Mahmoodi, Niyaz Mohammad; Arami, Mokhtar; Bahrami, Hajir; Mazaheri, Firoozmehr

2009-01-01

In this paper, the surface modification of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N, N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB.B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules.

Phase Behavior and Conductivity of Phosphonated Block Copolymers Containing Ionic Liquids

NASA Astrophysics Data System (ADS)

Jung, Ha Young; Kim, Sung Yeon; Park, Moon Jeong

2015-03-01

As the focus on proton exchange fuel cells continues to escalate in the era of alternative energy systems, the rational design of sulfonated polymers has emerged as a key technique for enhancing device efficiency. While the sulfonic acid group guarantees high proton conductivity of membranes under humidified conditions, the growing need for high temperature operation has discouraged their practical uses in fuel cells. In this respect, phosphonated polymers have drawn intensive attention in recent years owing to their self-dissociation ability. In this study, we have synthesized a set of phosphonated block copolymers, poly(styrenephosphonate-methylbutylene) (PSP- b - PMB), by varying phosphonation level (PL). A wide variety of self-assembled morphologies, i.e., disordered, lamellar, hexagonally perforated lamellae and hexagonally packed cylindrical phases, were observed with PL. Remarkably, upon comparing the morphology of PSP- b-PMB and that of sulfonated analog, we found distinctly dissimilar domain sizes at the same molecular weight and composition. A range of ionic liquids (ILs) were incorporated into the PSP- b-PMB block copolymers and their ion transport properties were examined. It has been revealed that the degree of confinement of ionic phases (domain size) impacts the ion mobility and proton dissociation efficiency of IL-containing polymers.

Poly(N-isopropylacrylamide) hydrogel/chitosan scaffold hybrid for three-dimensional stem cell culture and cartilage tissue engineering.

PubMed

Mellati, Amir; Kiamahalleh, Meisam Valizadeh; Madani, S Hadi; Dai, Sheng; Bi, Jingxiu; Jin, Bo; Zhang, Hu

2016-11-01

Providing a controllable and definable three-dimensional (3D) microenvironment for chondrogenic differentiation of mesenchymal stem cells (MSCs) remains a great challenge for cartilage tissue engineering. In this work, poly(N-isopropylacrylamide) (PNIPAAm) polymers with the degrees of polymerization of 100 and 400 (NI100 and NI400) were prepared and the polymer solutions were introduced into the preprepared chitosan porous scaffolds (CS) to form hybrids (CSNI100 and CSNI400, respectively). SEM images indicated that the PNIPAAm gel partially occupied chitosan pores while the interconnected porous structure of chitosan was preserved. MSCs were incorporated within the hybrid and cell proliferation and chondrogenic differentiation were monitored. After 7-day incubation of the cell-laden constructs in a growth medium, the cell viability in CSNI100 and CSNI400 were 54 and 108% higher than that in CS alone, respectively. Glycosaminoglycan and total collagen contents increased 2.6- and 2.5-fold after 28-day culture of cell-laden CSNI400 in the chondrogenic medium. These results suggest that the hybrid structure composed of the chitosan porous scaffold and the well-defined PNIPAAm hydrogel, in particular CSNI400, is suitable for 3D stem cell culture and cartilage tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2764-2774, 2016. © 2016 Wiley Periodicals, Inc.

Functional modification of chitosan for biomedical application

NASA Astrophysics Data System (ADS)

Tang, Ruogu

Chitosan is a linear polysaccharide. Normally commercial chitosan consists of randomly distributed beta-(1-4)-linked D-glucosamine (deacetylated proportion) and N-acetyl-D-glucosamine (acetylated proportion) together. Chitosan has been proved to be a multifunctional biopolymer that presents several unique properties due to free amino groups in the repeating unit therefore chitosan has been widely applied in various areas. To be specific, provided by the excellent biocompatibility, chitosan is expected to be used in biological and medical applications including wound dressing, implants, drug carrier/delivery, etc. In this thesis, we worked on chitosan functionalization for biomedical application. The thesis are composed of three parts: In the first part, we focused on modifying the chitosan thin film, chemically introducing the nitric oxide functional groups on chitosan film. We covalently bonded small molecule diazeniumdiolates onto the chitosan films and examined the antimicrobial function and biocompatibility. Commercial chitosan was cast into films from acidic aqueous solutions. Glutaraldehyde reacted with the chitosan film to introduce aldehyde groups onto the chitosan film (GA-CS film). GA-CS reacted with a small molecule NO donor, NOC-18, to covalently immobilize NONO groups onto the polymer (NO-CS film). The-CHO and [NONO] group were verified by FT IR, UV and Griess reagent. The NO releasing rate in aqueous solution and and thermal stability were studied quantitatively to prove its effectiveness. A series of antimicrobial tests indicated that NO-CS films have multiple functions: 1. It could inhibit the bacteria growth in nutrient rich environment; 2. It could directly inactivate bacteria and biofilm; 3. It could reduce the bacteria adherence on the film surface as well as inhibit biofilm formation. In addition, the NO-CS film was proved to be biocompatible with cell and it was also compatible with other antibiotics like Amoxicillin. In the second part, we

Effects of post-session administration of methylene blue on fear extinction and contextual memory in adults with claustrophobia.

PubMed

Telch, Michael J; Bruchey, Aleksandra K; Rosenfield, David; Cobb, Adam R; Smits, Jasper; Pahl, Sandra; Gonzalez-Lima, F

2014-10-01

Preclinical studies have shown that low-dose methylene blue increases mitochondrial cytochrome oxidase activity in the brain and improves memory retention after learning tasks, including fear extinction. The authors report on the first controlled experiment to examine the memory-enhancing effects of posttraining methylene blue administration on retention of fear extinction and contextual memory following fear extinction training. Adult participants displaying marked claustrophobic fear were randomly assigned to double-blind administration of 260 mg of methylene blue (N=23) or administration of placebo (N=19) immediately following six 5-minute extinction trials in an enclosed chamber. Retesting occurred 1 month later to assess fear renewal as indexed by peak fear during exposure to a nontraining chamber, with the prediction that the effects of methylene blue would vary as a function of fear reduction achieved during extinction training. Incidental contextual memory was assessed 1 and 30 days after training to assess the cognitive-enhancing effects of methylene blue independent of its effects on fear attenuation. Consistent with predictions, participants displaying low end fear posttraining showed significantly less fear at the 1-month follow-up if they received methylene blue posttraining compared with placebo. In contrast, participants displaying moderate to high levels of posttraining fear tended to fare worse at the follow-up if they received methylene blue posttraining. Methylene blue's enhancement of contextual memory was unrelated to initial or posttraining claustrophobic fear. Methylene blue enhances memory and the retention of fear extinction when administered after a successful exposure session but may have a deleterious effect on extinction when administered after an unsuccessful exposure session.

Evaluation of antioxidant activities and chemical analysis of sulfated chitosan from Sepia prashadi.

PubMed

Seedevi, Palaniappan; Moovendhan, Meivelu; Vairamani, Shanmugam; Shanmugam, Annaian

2017-06-01

The chitin and chitosan of S. prashadi was prepared through demineralization, deproteinzation, deacetylation process and sulfation were carried by chlorosulfonic acid in N,N-dimethylformamide. The sulfate content in chitosan was found to be 18.9%. The carbon, hydrogen and nitrogen composition of the sulfated chitosan were recorded 39.09%, 6.95% and 6.58% respectively. The structural analysis was done by using FT-IR and NMR spectroscopy technique. The DSC curves of sulfated chitosan showed a large endothermic peak resolved with T o value of 54.57°C and T P value of 97.46°C. The morphology of sulfated chitin and sulfated chitosan were studied by SEM. The Further in vitro antioxidant activity of sulfated chitosan was screened by scavenging activity of superoxide radical assay, hydroxyl radical scavenging assay, metal-ion chelating effect and reducing power. Its anticoagulant activity was tested for human plasma with respect to Activated Partial Thromboplastin Time (APTT) and Prothrombin Time (PT). Results prove that sulfated chitosan has potent antioxidant and anticoagulant activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Neurospora crassa transcriptomics reveals oxidative stress and plasma membrane homeostasis biology genes as key targets in response to chitosan

PubMed Central

Lopez-Moya, Federico; Kowbel, David; Nueda, Ma José; Palma-Guerrero, Javier; Glass, N. Louise; Lopez-Llorca, Luis Vicente

2016-01-01

Chitosan is a natural polymer with antimicrobial activity. Chitosan causes plasma membrane permeabilization and induction of intracellular reactive oxygen species (ROS) in Neurospora crassa. We have determined the transcriptional profile of N. crassa to chitosan and identified the main gene targets involved in the cellular response to this compound. Global network analyses showed membrane, transport and oxidoreductase activity as key nodes affected by chitosan. Activation of oxidative metabolism indicates the importance of ROS and cell energy together with plasma membrane homeostasis in N. crassa response to chitosan. Deletion strain analysis of chitosan susceptibility pointed, NCU03639 encoding a class 3 lipase, involved in plasma membrane repair by lipid replacement and NCU04537 a MFS monosaccharide transporter related with assimilation of simple sugars, as main gene targets of chitosan. NCU10521, a glutathione S-transferase-4 involved in the generation of reducing power for scavenging intracellular ROS is also a determinant chitosan gene target. Ca2+ increased tolerance to chitosan in N. crassa. Growth of NCU10610 (fig 1 domain) and SYT1 (a synaptotagmin) deletion strains was significantly increased by Ca2+ in presence of chitosan. Both genes play a determinant role in N. crassa membrane homeostasis. Our results are of paramount importance for developing chitosan as antifungal. PMID:26694141

Removal of nitrate and phosphate using chitosan/Al2O3/Fe3O4 composite nanofibrous adsorbent: Comparison with chitosan/Al2O3/Fe3O4 beads.

PubMed

Bozorgpour, Farahnaz; Ramandi, Hossein Fasih; Jafari, Pooya; Samadi, Saman; Yazd, Shabnam Sharif; Aliabadi, Majid

2016-12-01

In the present study the chitosan/Al 2 O 3 /Fe 3 O 4 composite nanofibrous adsorbent was prepared by electrospinning process and its application for the removal of nitrate and phosphate were compared with chitosan/Al 2 O 3 /Fe 3 O 4 composite bead adsorbent. The influence of Al 2 O 3 /Fe 3 O 4 composite content, pH, contact time, nitrate and phosphate initial concentrations and temperature on the nitrate and phosphate sorption using synthesized bead and nanofibrous adsorbents was investigated in a single system. The reusability of chitosan/Al 2 O 3 /Fe 3 O 4 composite beads and nanofibers after five sorption-desorption cycles were carried out. The Box-Behnken design was used to investigate the interaction effects of adsorbent dosage, nitrate and phosphate initial concentrations on the nitrate and phosphate removal efficiency. The pseudo-second-order kinetic model and known Freundlich and Langmuir isotherm models were used to describe the kinetic and equilibrium data of nitrate and phosphate sorption using chitosan/Al 2 O 3 /Fe 3 O 4 composite beads and nanofibers. The influence of other anions including chloride, fluoride and sulphate on the sorption efficiency of nitrate and phosphate was examined. The obtained results revealed the higher potential of chitosan/Al 2 O 3 /Fe 3 O 4 composite nanofibers for nitrate and phosphate compared with chitosan/Al 2 O 3 /Fe 3 O 4 composite beads. Copyright © 2016 Elsevier B.V. All rights reserved.

Chitin, Chitosan, and Its Derivatives for Wound Healing: Old and New Materials

PubMed Central

Azuma, Kazuo; Izumi, Ryotaro; Osaki, Tomohiro; Ifuku, Shinsuke; Morimoto, Minoru; Saimoto, Hiroyuki; Minami, Saburo; Okamoto, Yoshiharu

2015-01-01

Chitin (β-(1-4)-poly-N-acetyl-d-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. It is often converted to its more deacetylated derivative, chitosan. Previously, many reports have indicated the accelerating effects of chitin, chitosan, and its derivatives on wound healing. More recently, chemically modified or nano-fibrous chitin and chitosan have been developed, and their effects on wound healing have been evaluated. In this review, the studies on the wound-healing effects of chitin, chitosan, and its derivatives are summarized. Moreover, the development of adhesive-based chitin and chitosan are also described. The evidence indicates that chitin, chitosan, and its derivatives are beneficial for the wound healing process. More recently, it is also indicate that some nano-based materials from chitin and chitosan are beneficial than chitin and chitosan for wound healing. Clinical applications of nano-based chitin and chitosan are also expected. PMID:25780874

Site-selective chemical modification of chymotrypsin using peptidyl derivatives bearing optically active diphenyl 1-amino-2-phenylethylphosphonate: Stereochemical effect of the diphenyl phosphonate moiety.

PubMed

Ono, Shin; Nakai, Takahiko; Kuroda, Hirofumi; Miyatake, Ryuta; Horino, Yoshikazu; Abe, Hitoshi; Umezaki, Masahito; Oyama, Hiroshi

2016-11-04

Diphenyl (α-aminoalkyl)phosphonates act as mechanism-based inhibitors against serine proteases by forming a covalent bond with the hydroxy group of the active center Ser residue. Because the covalent bond was found to be broken and replaced by 2-pyridinaldoxime methiodide (2PAM), we employed a peptidyl derivative bearing diphenyl 1-amino-2-phenylethylphosphonate moiety (Phe(p) (OPh)2 ) to target the active site of chymotrypsin and to selectively anchor to Lys175 in the vicinity of the active site. Previously, it was reported that the configuration of the α-carbon of phosphorus in diphenyl (α-aminoalkyl)phosphonates affects the inactivation reaction of serine proteases, i.e., the (R)-enantiomeric diphenyl phosphonate is comparable to l-amino acids and it effectively reacts with serine proteases, whereas the (S)-enantiomeric form does not. In this study, we evaluated the stereochemical effect of the phosphonate moiety on the selective chemical modification. Epimeric dipeptidyl derivatives, Ala-(R or S)-Phe(p) (OPh)2 , were prepared by separation with RP-HPLC. A tripeptidyl (R)-epimer (Ala-Ala-(R)-Phe(p) (OPh)2 ) exhibited a more potent inactivation ability against chymotrypsin than the (S)-epimer. The enzyme inactivated by the (R)-epimer was more effectively reactivated with 2PAM than the enzyme inactivated by the (S)-epimer. Finally, N-succinimidyl (NHS) active ester derivatives, NHS-Suc-Ala-Ala- (R or S)-Phe(p) (OPh)2 , were prepared, and we evaluated their action when modifying Lys175 in chymotrypsin. We demonstrated that the epimeric NHS derivative that possessed the diphenyl phosphonate moiety with the (R)-configuration effectively modified Lys175 in chymotrypsin, whereas that with the (S)-configuration did not. These results demonstrate the utility of peptidyl derivatives that bear an optically active diphenyl phosphonate moiety as affinity labeling probes in protein bioconjugation. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 521-530, 2016. �

Methylene blue prevents retinal damage in an experimental model of ischemic proliferative retinopathy.

PubMed

Rey-Funes, Manuel; Larrayoz, Ignacio M; Fernández, Juan C; Contartese, Daniela S; Rolón, Federico; Inserra, Pablo I F; Martínez-Murillo, Ricardo; López-Costa, Juan J; Dorfman, Verónica B; Martínez, Alfredo; Loidl, César F

2016-06-01

Perinatal asphyxia induces retinal lesions, generating ischemic proliferative retinopathy, which may result in blindness. Previously, we showed that the nitrergic system was involved in the physiopathology of perinatal asphyxia. Here we analyze the application of methylene blue, a well-known soluble guanylate cyclase inhibitor, as a therapeutic strategy to prevent retinopathy. Male rats (n = 28 per group) were treated in different ways: 1) control group comprised born-to-term animals; 2) methylene blue group comprised animals born from pregnant rats treated with methylene blue (2 mg/kg) 30 and 5 min before delivery; 3) perinatal asphyxia (PA) group comprised rats exposed to perinatal asphyxia (20 min at 37°C); and 4) methylene blue-PA group comprised animals born from pregnant rats treated with methylene blue (2 mg/kg) 30 and 5 min before delivery, and then the pups were subjected to PA as above. For molecular studies, mRNA was obtained at different times after asphyxia, and tissue was collected at 30 days for morphological and biochemical analysis. Perinatal asphyxia produced significant gliosis, angiogenesis, and thickening of the inner retina. Methylene blue treatment reduced these parameters. Perinatal asphyxia resulted in a significant elevation of the nitrergic system as shown by NO synthase (NOS) activity assays, Western blotting, and (immuno)histochemistry for the neuronal isoform of NOS and NADPH-diaphorase activity. All these parameters were also normalized by the treatment. In addition, methylene blue induced the upregulation of the anti-angiogenic peptide, pigment epithelium-derived factor. Application of methylene blue reduced morphological and biochemical parameters of retinopathy. This finding suggests the use of methylene blue as a new treatment to prevent or decrease retinal damage in the context of ischemic proliferative retinopathy. Copyright © 2016 the American Physiological Society.

Hydrothermal synthesis for new multifunctional materials: A few examples of phosphates and phosphonate-based hybrid materials

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

Rueff, Jean-Michel, E-mail: jean-michel.rueff@ensicaen.fr; Poienar, Maria; Guesdon, Anne

Novel physical or chemical properties are expected in a great variety of materials, in connection with the dimensionality of their structures and/or with their nanostructures, hierarchical superstructures etc. In the search of new advanced materials, the hydrothermal technique plays a crucial role, mimicking the nature able to produce fractal, hyperbranched, urchin-like or snow flake structures. In this short review including new results, this will be illustrated by examples selected in two types of materials, phosphates and phosphonates, prepared by this method. The importance of the synthesis parameters will be highlighted for a magnetic iron based phosphates and for hybrids containingmore » phosphonates organic building units crystallizing in different structural types. - Graphical abstract: Phosphate dendrite like and phosphonate platelet crystals.« less

Mucoadhesion mechanism of chitosan and thiolated chitosan-poly(isobutyl cyanoacrylate) core-shell nanoparticles.

PubMed

Bravo-Osuna, Irene; Vauthier, Christine; Farabollini, Alessandra; Palmieri, Giovanni Filippo; Ponchel, Gilles

2007-04-01

The study is focused on the evaluation of the potential bioadhesive behaviour of chitosan and thiolated chitosan (chitosan-TBA)-coated poly(isobutyl cyanoacrylates) (PIBCA) nanoparticles. Nanoparticles were obtained by radical emulsion polymerisation with chitosan of different molecular weight and with different proportions of chitosan/chitosan-TBA. Mucoadhesion was ex vivo evaluated under static conditions by applying nanoparticle suspensions on rat intestinal mucosal surfaces and evaluating the amount of nanoparticles remaining attached to the mucosa after incubation. The analysis of the results obtained demonstrated that the presence of either chitosan or thiolated chitosan on the PIBCA nanoparticle surface clearly enhanced the mucoadhesion behaviour thanks to non-covalent interactions (ionic interaction and hydrogen bonds) with mucus chains. Both, the molecular weight of chitosan and the proportion of chitosan-TBA in the formulation influenced the nanoparticle hydrodynamic diameter and hence their transport through the mucus layer. Improved interpenetration ability with the mucus chain during the attachment process was suggested for the chitosan of high molecular weight, enhancing the bioadhesiveness of the system. The presence of thiol groups on the nanoparticle surface at high concentration (200 x 10(-6) micromol SH/cm2) increased the mucoadhesion capacity of nanoparticles by forming covalent bonds with the cysteine residues of the mucus glycoproteins.

Structure and Order of Phosphonic Acid-Based Self-Assembled Monolayers on Si(100)

PubMed Central

Dubey, Manish; Weidner, Tobias; Gamble, Lara J.; Castner, David G.

2010-01-01

Organophosphonic acid self-assembled monolayers (SAMs) on oxide surfaces have recently seen increased use in electrical and biological sensor applications. The reliability and reproducibility of these sensors require good molecular organization in these SAMs. In this regard, packing, order and alignment in the SAMs is important, as it influences the electron transport measurements. In this study, we examine the order of hydroxyl- and methyl- terminated phosphonate films deposited onto silicon oxide surfaces by the tethering by aggregation and growth method using complementary, state-of-art surface characterization tools. Near edge x-ray absorption fine structure (NEXAFS) spectroscopy and in situ sum frequency generation (SFG) spectroscopy are used to study the order of the phosphonate SAMs in vacuum and under aqueous conditions, respectively. X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry results show that these samples form chemically intact monolayer phosphonate films. NEXAFS and SFG spectroscopy showed that molecular order exists in the octadecylphosphonic acid and 11-hydroxyundecylphosphonic acid SAMs. The chain tilt angles in these SAMs were approximately 37° and 45°, respectively. PMID:20735054

Chemoselective recognition with phosphonate cavitands: the ephedrine over pseudoephedrine case.

PubMed

Biavardi, Elisa; Ugozzoli, Franco; Massera, Chiara

2015-02-25

Complete discrimination of ephedrine and pseudoephedrine, both in solution and in the solid state, was achieved with a phosphonate cavitand receptor. The molecular origin of the epimer discrimination was revealed by the crystal structure of the respective complexes.

Synthesis of carboxymethylated and quaternized chitosans and their therapeutic effect on nonalcoholic Fatty liver disease.

PubMed

Liu, Xiaofei; Yang, Fan; Song, Tao; Zeng, Anrong; Wang, Qi; Sun, Zhong; Shen, Jun

2011-10-12

O-Carboxymethyl chitosan (O-CMCs) and N-((2-hydroxy-3-N,N-dimethylhexadecylammonium)propyl)chitosan chloride (N-CQCs) were synthesized for nonalcoholic fatty liver disease (NAFLD) treatment. The weight-average weight and substitution degree of O-CMCs and N-CQCs were 6.5 × 10(4) and 0.72 and 7.9 × 10(4) and 0.21, respectively. O-CMCs was negatively charged with a zeta-potential value of -31.82 mV, whereas that of N-CQCs was +36.1 mV, and both showed low cytotoxcity. Serum lipid level and liver fat accumulation were reduced with chitosan and its two derivatives. Furthermore, mRNA and protein expression assay of hepatic lipid metabolism enzymes and low-density lipoprotein receptor (LDL-R) were observed by RT-PCR and Western blot. Results showed that N-CQCs exhibited a more evident desired effect than chitosan and O-CMCs, indicating that amphiphilicity, solubility, and surface charge of chitosan and its two derivatives played roles in the expression of hepatic lipid metabolism enzymes and LDL-R. Therefore, dietary supplementation of O-CMCs and N-CQCs can alleviate the high fat diet induced aberrations related to NAFLD by their antilipidemic property.

Chitosan

PubMed Central

Smith, Alan; Perelman, Michael; Hinchcliffe, Michael

2014-01-01

The nasal route is attractive for the delivery of vaccines in that it not only offers an easy to use, non-invasive, needle-free alternative to more conventional parenteral injection, but it also creates an opportunity to elicit both systemic and (crucially) mucosal immune responses which may increase the capability of controlling pathogens at the site of entry. Immune responses to “naked” antigens are often modest and it is widely accepted that incorporation of an adjuvant is a prerequisite for the achievement of clinically effective nasal vaccines. Many existing adjuvants are sub-optimal or unsuitable because of local toxicity or poor enhancement of immunogenicity. Chitosan, particularly chitosan salts, have now been used in several preclinical and clinical studies with good tolerability, excellent immune stimulation and positive clinical results across a number of infections. Particularly significant evidence supporting chitosan as an adjuvant for nasal vaccination comes from clinical investigations on a norovirus vaccine; this demonstrated the ability of chitosan (ChiSys®), when combined with monophosphoryl lipid, to evoke robust immunological responses and confer protective immunity following (enteral) norovirus challenge. This article summarizes the totality of the meaningful information (including key unpublished data) supporting the development of chitosan-adjuvanted vaccines. PMID:24346613

Lyophilized insulin nanoparticles prepared from quaternized N-aryl derivatives of chitosan as a new strategy for oral delivery of insulin: in vitro, ex vivo and in vivo characterizations.

PubMed

Mahjub, Reza; Radmehr, Moojan; Dorkoosh, Farid Abedin; Ostad, Seyed Naser; Rafiee-Tehrani, Morteza

2014-12-01

The purpose of this research was the development, in vitro, ex vivo and in vivo characterization of lyophilized insulin nanoparticles prepared from quaternized N-aryl derivatives of chitosan. Insulin nanoparticles were prepared from methylated N-(4-N,N-dimethylaminobenzyl), methylated N-(4 pyridinyl) and methylated N-(benzyl). Insulin nanoparticles containing non-modified chitosan and also trimethyl chiotsan (TMC) were also prepared as control. The effects of the freeze-drying process on physico-chemical properties of nanoparticles were investigated. The release of insulin from the nanoparticles was studied in vitro. The mechanism of the release of insulin from different types of nanoparticles was determined using curve fitting. The secondary structure of the insulin released from the nanoparticles was analyzed using circular dichroism and the cell cytotoxicity of nanoparticles on a Caco-2 cell line was determined. Ex vivo studies were performed on excised rat jejunum using Frantz diffusion cells. In vivo studies were performed on diabetic male Wistar rats and blood glucose level and insulin serum concentration were determined. Optimized nanoparticles with proper physico-chemical properties were obtained. The lyophilization process was found to cause a decrease in zeta potential and an increase in PdI as well as and a decrease in entrapment efficiency (EE%) and loading efficiency (LE%) but conservation in size of nanoparticles. Atomic force microscopy (AFM) images showed non-aggregated, stable and spherical to sub-spherical nanoparticles. The in vitro release study revealed higher release rates for lyophilized compared to non-lyophilized nanoparticles. Cytotoxicity studies on Caco-2 cells revealed no significant cytotoxicity for prepared nanoparticles after 3-h post-incubation but did show the concentration-dependent cytotoxicity after 24 h. The percentage of cumulative insulin determined from ex vivo studies was significantly higher in nanoparticles prepared

Coalesced chitosan activated carbon composite for batch and fixed-bed adsorption of cationic and anionic dyes.

PubMed

Auta, M; Hameed, B H

2013-05-01

A renewable waste tea activated carbon (WTAC) was coalesced with chitosan to form composite adsorbent used for waste water treatment. Adsorptive capacities of crosslinked chitosan beads (CCB) and its composite (WTAC-CCB) for Methylene blue dye (MB) and Acid blue 29 (AB29) were evaluated through batch and fixed-bed studies. Langmuir, Freundlich and Temkin adsorption isotherms were tested for the adsorption process and the experimental data were best fitted by Langmuir model and least by Freundlich model; the suitability of fitness was adjudged by the Chi-square (χ(2)) and Marquadt's percent standard deviation error functions. Judging by the values of χ(2), pseudo-second-order reaction model best described the adsorption process than pseudo-first-order kinetic model for MB/AB29 on both adsorbents. After five cycles of adsorbents desorption test, more than 50% WTAC-CCB adsorption efficiency was retained while CCB had <20% adsorption efficiency. The results of this study revealed that WTAC-CCB composite is a promising adsorbent for treatment of anionic and cationic dyes in effluent wastewaters. Copyright © 2012 Elsevier B.V. All rights reserved.

Neurospora crassa transcriptomics reveals oxidative stress and plasma membrane homeostasis biology genes as key targets in response to chitosan

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

Lopez-Moya, Federico; Kowbel, David; Nueda, Ma Jose

Chitosan is a natural polymer with antimicrobial activity. Chitosan causes plasma membrane permeabilization and induction of intracellular reactive oxygen species (ROS) in Neurospora crassa. In this paper, we have determined the transcriptional profile of N. crassa to chitosan and identified the main gene targets involved in the cellular response to this compound. Global network analyses showed membrane, transport and oxidoreductase activity as key nodes affected by chitosan. Activation of oxidative metabolism indicates the importance of ROS and cell energy together with plasma membrane homeostasis in N. crassa response to chitosan. Deletion strain analysis of chitosan susceptibility pointed NCU03639 encoding amore » class 3 lipase, involved in plasma membrane repair by lipid replacement, and NCU04537 a MFS monosaccharide transporter related to assimilation of simple sugars, as main gene targets of chitosan. NCU10521, a glutathione S-transferase-4 involved in the generation of reducing power for scavenging intracellular ROS is also a determinant chitosan gene target. Ca 2+ increased tolerance to chitosan in N. crassa. Growth of NCU10610 (fig 1 domain) and SYT1 (a synaptotagmin) deletion strains was significantly increased by Ca 2+ in the presence of chitosan. Both genes play a determinant role in N. crassa membrane homeostasis. Finally, our results are of paramount importance for developing chitosan as an antifungal.« less

Neurospora crassa transcriptomics reveals oxidative stress and plasma membrane homeostasis biology genes as key targets in response to chitosan

DOE PAGES

Lopez-Moya, Federico; Kowbel, David; Nueda, Ma Jose; ...

2015-12-01

Chitosan is a natural polymer with antimicrobial activity. Chitosan causes plasma membrane permeabilization and induction of intracellular reactive oxygen species (ROS) in Neurospora crassa. In this paper, we have determined the transcriptional profile of N. crassa to chitosan and identified the main gene targets involved in the cellular response to this compound. Global network analyses showed membrane, transport and oxidoreductase activity as key nodes affected by chitosan. Activation of oxidative metabolism indicates the importance of ROS and cell energy together with plasma membrane homeostasis in N. crassa response to chitosan. Deletion strain analysis of chitosan susceptibility pointed NCU03639 encoding amore » class 3 lipase, involved in plasma membrane repair by lipid replacement, and NCU04537 a MFS monosaccharide transporter related to assimilation of simple sugars, as main gene targets of chitosan. NCU10521, a glutathione S-transferase-4 involved in the generation of reducing power for scavenging intracellular ROS is also a determinant chitosan gene target. Ca 2+ increased tolerance to chitosan in N. crassa. Growth of NCU10610 (fig 1 domain) and SYT1 (a synaptotagmin) deletion strains was significantly increased by Ca 2+ in the presence of chitosan. Both genes play a determinant role in N. crassa membrane homeostasis. Finally, our results are of paramount importance for developing chitosan as an antifungal.« less

Cytotoxicity and biocompatibility evaluation of N,O-carboxymethyl chitosan/oxidized alginate hydrogel for drug delivery application.

PubMed

Li, Xingyi; Kong, Xiangye; Zhang, Zhaoliang; Nan, Kaihui; Li, LingLi; Wang, XianHou; Chen, Hao

2012-06-01

In this paper, covalently cross-linked hydrogel composed of N,O-carboxymethyl chitosan and oxidized alginate was developed intending for drug delivery application. In vitro/vivo cytocompatibility and biocompatibility of the developed hydrogel were preliminary evaluated. In vitro cytocompatibility test showed that the developed hydrogel exhibited good cytocompatibility against NH3T3 cells after 3-day incubation. According to the results of acute toxicity test, there was no obvious cytotoxicity for major organs during the period of 21-day intraperitoneal administration. Meanwhile, the developed hydrogel did not induce any cutaneous reaction within 72 h of subcutaneous injection followed by slow degradation and adsorption with the time evolution. Moreover, the extraction of developed hydrogel had nearly 0% of hemolysis ratio, which indicated the good hemocompatibility of hydrogel. Based on the above results, it may be concluded that the developed N,O-carboxymethyl chitosan/oxidized alginate hydrogel with non-cytotoxicity and good biocompatibility might suitable for the various drug delivery applications. Copyright © 2012 Elsevier B.V. All rights reserved.

pH-Dependence of Binding Constants and Desorption Rates of Phosphonate- and Hydroxamate-Anchored [Ru(bpy)3]2+ on TiO2 and WO3.

PubMed

Esarey, Samuel L; Bartlett, Bart M

2018-04-17

The binding constants and rate constants for desorption of the modified molecular dye [Ru(bpy) 3 ] 2+ anchored by either phosphonate or hydroxamate on the bipyridine ligand to anatase TiO 2 and WO 3 have been measured. In aqueous media at pH 1-10, repulsive electrostatic interactions between the negatively charged anchor and the negatively charged surface govern phosphonate desorption under neutral and basic conditions for TiO 2 anatase due to the high acidity of phosphonic acid (p K a,4 = 5.1). In contrast, the lower acidity of hydroxamate (p K a,1 = 6.5, p K a,2 = 9.1) leads to little change in adsorption/desorption properties as a function of pH from 1 to 7. The binding constant for hydroxamate is 10 3 in water, independent of pH in this range. These results are true for WO 3 as well, but are not reported at pH > 4 due to its Arrhenius acidity. Kinetics for desorption as a function of pH are reported, with a proposed mechanism for phosphonate desorption at high pH being the electrostatic repulsion of negative charges between the surface and the anionic anchor. Further, the hydroxamic acid anchor itself is likely the site of quasi-reversible redox activity in [Ru(bpy) 2 (2,2'-bpy-4,4'-(C(O)N(OH)) 2 )] 2+ , which does not lead to any measurable deterioration of the complex within 2 h of dark cyclic voltammogram scans in aqueous media. These results posit phosphonate as the preferred anchoring group under acidic conditions and hydroxamate for neutral/basic conditions.

Direct assembly synthesis of metal complex-semiconductor hybrid photocatalysts anchored by phosphonate for highly efficient CO2 reduction.

PubMed

Suzuki, Tomiko M; Tanaka, Hiromitsu; Morikawa, Takeshi; Iwaki, Masayo; Sato, Shunsuke; Saeki, Shu; Inoue, Masae; Kajino, Tsutomu; Motohiro, Tomoyoshi

2011-08-14

Hybrid photocatalysts consisting of a ruthenium complex and p-type photoactive N-doped Ta(2)O(5) anchored with an organic group were successfully synthesized by a direct assembly method. The photocatalyst anchored by phosphonate exhibited excellent photoconversion activity of CO(2) to formic acid under visible-light irradiation with respect to the reaction rate and stability. This journal is © The Royal Society of Chemistry 2011

Bone-Induced Chondroinduction in Sheep Jamshidi Biopsy Defects with and without Treatment by Subchondral Chitosan-Blood Implant

PubMed Central

Bell, Angela D.; Lascau-Coman, Viorica; Sun, Jun; Chen, Gaoping; Lowerison, Mark W.; Hurtig, Mark B.

2013-01-01

Objective: Delivery of chitosan to subchondral bone is a novel approach for augmented marrow stimulation. We evaluated the effect of 3 presolidified chitosan-blood implant formulations on osteochondral repair progression compared with untreated defects. Design: In N = 5 adult sheep, six 2-mm diameter Jamshidi biopsy holes were created bilaterally in the medial femoral condyle and treated with presolidified chitosan-blood implant with fluorescent chitosan tracer (10 kDa, 40 kDa, or 150k Da chitosan, left knee) or left to bleed (untreated, right knee). Implant residency and osteochondral repair were assessed at 1 day (N = 1), 3 weeks (N = 2), or 3 months (N = 2) postoperative using fluorescence microscopy, histomorphometry, stereology, and micro–computed tomography. Results: Chitosan implants were retained in 89% of treated Jamshidi holes up to 3 weeks postoperative. At 3 weeks, biopsy sites were variably covered by cartilage flow, and most bone holes contained cartilage flow fragments and heterogeneous granulation tissues with sparse leukocytes, stromal cells, and occasional adipocytes (volume density 1% to 3%). After 3 months of repair, most Jamshidi bone holes were deeper, remodeling at the edges, filled with angiogenic granulation tissue, and lined with variably sized chondrogenic foci fused to bone trabeculae or actively repairing bone plate. The 150-kDa chitosan implant elicited more subchondral cartilage formation compared with 40-kDa chitosan-treated and control defects (P < 0.05, N = 4). Treated defects contained more mineralized repair tissue than control defects at 3 months (P < 0.05, N = 12). Conclusion: Bone plate–induced chondroinduction is an articular cartilage repair mechanism. Jamshidi biopsy repair takes longer than 3 months and can be influenced by subchondral chitosan-blood implant. PMID:26069656

Synthesis and Characterization of a Chitosan Derivative for Electro-Optical Applications

NASA Technical Reports Server (NTRS)

Prastofer, Thomas

1996-01-01

Chitin is a naturally occurring polymer of alpha(1-4) poly N-acetylglucosamine found primarily in the shells of crustaceans and insects. This polymer is chemically and thermally stable and physically durable as a consequence of hydrogen bonding which causes the alignment and ordering of the polymer chains into microcrystals which aggregate into sheets with chiral nematic order. Industry has attempted to take advantage of chitin's properties and low cost (chitin is a waste product of the shellfish industry) to produce durable fibers and other products. This has been largely unsuccessful because of chitin's non reactivity and insolubility. Chitosan is the deacetylation product of chitin and retains many of the structural properties of chitin. Unlike chitin, chitosan is soluble in aqueous solution at reduced pH making it easier to be processed into fibers and films than chitin. Chitosan and its derivatives are now used in such commercial applications as wound dressings, waste water treatment, and in pharmaceuticals. In this study, we have synthesized a chitosan derivative, N-para-nitrophenyl chitosan (NPNPC), as a model material with potential applications in electro optics.

Preparation, characterization, and potential application of chitosan, chitosan derivatives, and chitosan metal nanoparticles in pharmaceutical drug delivery

PubMed Central

Ahmed, Tarek A; Aljaeid, Bader M

2016-01-01

Naturally occurring polymers, particularly of the polysaccharide type, have been used pharmaceutically for the delivery of a wide variety of therapeutic agents. Chitosan, the second abundant naturally occurring polysaccharide next to cellulose, is a biocompatible and biodegradable mucoadhesive polymer that has been extensively used in the preparation of micro-as well as nanoparticles. The prepared particles have been exploited as a potential carrier for different therapeutic agents such as peptides, proteins, vaccines, DNA, and drugs for parenteral and nonparenteral administration. Therapeutic agent-loaded chitosan micro- or nanoparticles were found to be more stable, permeable, and bioactive. In this review, we are highlighting the different methods of preparation and characterization of chitosan micro- and nanoparticles, while reviewing the pharmaceutical applications of these particles in drug delivery. Moreover, the roles of chitosan derivatives and chitosan metal nanoparticles in drug delivery have been illustrated. PMID:26869768

Yield Improvement and Energy Savings Uing Phosphonates as Additives in Kraft pulping

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

Ulrike W. Tschirner; Timothy Smith

2007-03-31

Project Objective: Develop a commercially viable modification to the Kraft process resulting in energy savings, increased yield and improved bleachability. Evaluate the feasibility of this technology across a spectrum of wood species used in North America. Develop detailed fundamental understanding of the mechanism by which phosphonates improve KAPPA number and yield. Evaluate the North American market potential for the use of phosphonates in the Kraft pulping process. Examine determinants of customer perceived value and explore organizational and operational factors influencing attitudes and behaviors. Provide an economic feasibility assessment for the supply chain, both suppliers (chemical supply companies) and buyers (Kraftmore » mills). Provide background to most effectively transfer this new technology to commercial mills.« less

A Methylene Blue–assisted Technique for Harvesting Lymph Nodes After Radical Surgery for Gastric Cancer

PubMed Central

Aoyama, Toru; Fujikawa, Hirohito; Cho, Haruhiko; Ogata, Takashi; Shirai, Junya; Hayashi, Tsutomu; Rino, Yasushi; Masuda, Munetaka; Oba, Mari S.; Morita, Satoshi

2015-01-01

Harvesting lymph nodes (LNs) after gastrectomy is essential for accurate staging. This trial evaluated the efficiency and quality of a conventional method and a methylene blue–assisted method in a randomized manner. The key eligibility criteria were as follows: (i) histologically proven adenocarcinoma of the stomach; (ii) clinical stage I-III; (iii) R0 resection planned by gastrectomy with D1+ or D2 lymphadenectomy. The primary endpoint was the ratio of the pathologic number of harvested LNs per time (minutes) as an efficacy measure. The secondary endpoint was the number of harvested LNs, as a quality measure. Between August 2012 and December 2012, 60 patients were assigned to undergo treatment using the conventional method (n=29) and the methylene blue dye method (n=31). The baseline demographics were mostly well balanced between the 2 groups. The number of harvested LNs (mean±SD) was 33.6±11.9 in the conventional arm and 43.4±13.9 in the methylene blue arm (P=0.005). The ratio of the number of the harvested LNs per time was 1.12±0.46 LNs/min in the conventional arm and 1.49±0.59 LNs/min in the methylene blue arm (P=0.010). In the subgroup analyses, the quality and efficacy were both superior for the methylene blue dye method compared with the conventional method. The methylene blue technique is recommended for harvesting LNs during gastric cancer surgery on the basis of both the quality and efficacy. PMID:25356528

Design, characterization and ex vivo evaluation of chitosan film integrating of insulin nanoparticles composed of thiolated chitosan derivative for buccal delivery of insulin.

PubMed

Mortazavian, Elaheh; Dorkoosh, Farid Abedin; Rafiee-Tehrani, Morteza

2014-05-01

The purpose of this study is to optimize and characterize of chitosan buccal film for delivery of insulin nanoparticles that were prepared from thiolated dimethyl ethyl chitosan (DMEC-Cys). Insulin nanoparticles composed of chitosan and dimethyl ethyl chitosan (DMEC) were also prepared as control groups. The release of insulin from nanoparticles was studied in vitro in phosphate buffer solution (PBS) pH 7.4. Optimization of chitosan buccal films has been carried out by central composite design (CCD) response surface methodology. Independent variables were different amounts of chitosan and glycerol as mucoadhesive polymer and plasticizer, respectively. Tensile strength and bioadhesion force were considered as dependent variables. Ex vivo study was performed on excised rabbit buccal mucosa. Optimized insulin nanoparticles were obtained with acceptable physicochemical properties. In vitro release profile of insulin nanoparticles revealed that the highest solubility of nanoparticles in aqueous media is related to DMEC-Cys nanoparticles. CCD showed that optimized buccal film containing 4% chitosan and 10% glycerol has 5.81 kg/mm(2) tensile strength and 2.47 N bioadhesion forces. Results of ex vivo study demonstrated that permeation of insulin nanoparticles through rabbit buccal mucosa is 17.1, 67.89 and 97.18% for chitosan, DMEC and DMEC-Cys nanoparticles, respectively. Thus, this study suggests that DMEC-Cys can act as a potential enhancer for buccal delivery of insulin.

Sustained methylene blue staining to guide anatomic hepatectomy for hepatocellular carcinoma: Initial experience and technical details.

PubMed

Shou-wang, Cai; Shi-zhong, Yang; Wen-ping, Lv; Geng, Chen; Wan-qing, Gu; Wei-dong, Duan; Wei-yi, Wang; Zhi-qiang, Huang; Jia-hong, Dong

2015-07-01

The boundary of the target hepatic segment within the liver parenchyma cannot be marked by the use of a conventional anatomic hepatectomy approach. This study describes a novel methylene blue staining technique for guiding the anatomic resection of hepatocellular carcinoma (HCC). Between February 2009 and February 2012, anatomic hepatectomy was performed in 106 patients with HCC via a novel, sustained methylene blue staining technique. Sustained staining was achieved by injecting methylene blue into the distal aspect of the portal vein after exposing Glisson's sheath. The hepatic pedicle was immediately ligated, and the hepatic parenchymal transection was performed along the interface between methylene blue stained tissue and unstained tissue. Anatomic hepatectomies included subsegmentectomy (n = 16), monosegmentectomy (n = 57), multisegmentectomy (n = 27), and hemihepatectomy (n = 6). The portal vein was injected successfully with methylene blue in 100% of cases, and complete staining of the target hepatic segment was achieved in 98 of 106 (92.5%) cases. Mean intraoperative bleeding was 360 ± 90 mL, and the postoperative complication rate was 24.5% (26/106). No perioperative mortality occurred. Operative margins were all negative on pathologic examination. Mean duration of postoperative follow-up was 40 months (range, 24-60). No local recurrence (around the operative margin) occurred. This novel technique of achieving sustained staining by injecting methylene blue then immediately ligating the hepatic pedicle is simple and feasible. It can guide the selection of the operative margin during hepatic parenchyma transection to improve the accuracy of anatomic hepatectomy for the treatment of HCC. Copyright © 2015 Elsevier Inc. All rights reserved.

Results of the Massachusetts methylene chloride end-users survey.

PubMed

Roelofs, Cora R; Ellenbecker, Michael J

2003-02-01

A survey of Massachusetts companies reporting use of methylene chloride between 1995 and 1999 was conducted to assess the status of industrial use of the chemical in 2000. Methylene chloride has had wide use in industry although it has been identified as potentially hazardous to exposed workers and the environment. New and tightened occupational and environmental regulations taking effect in the 1990s were hypothesized to have reduced use of the chemical in Massachusetts. Substitute technologies, especially aqueous cleaning, were expected to have replaced methylene chloride in many industries. Seventeen of the 21 Massachusetts manufacturing companies reporting use of over 10,000 lb/y of methylene chloride between 1995 and 1999 were surveyed by telephone regarding their experiences of methylene chloride use and elimination and/or replacement. Fifteen of the 17 companies had either eliminated (10) or reduced to below 10,000 lbs/yr (5) their use of methylene chloride at the time of the survey in 2000. Many of the surveyed companies moved to aqueous cleaning from methylene chloride degreasing operations. Environmental concerns were the most popular reason given for eliminating or reducing use of methylene chloride. Worker health and safety concerns, especially concern about compliance with the 1997 Occupational Safety and Health Administration methylene chloride standard, were also a motivation. In general, the companies associated many benefits and few problems with eliminating or reducing use of methylene chloride. Exposure reduction strategies based on toxics use reduction techniques appear to be feasible for many manufacturing companies. However, research should be conducted to assess the introduction of new hazards as a result of tightened regulations on methylene chloride.

Gene silencing activity of siRNA polyplexes based on thiolated N,N,N-trimethylated chitosan.

PubMed

Varkouhi, Amir K; Verheul, Rolf J; Schiffelers, Raymond M; Lammers, Twan; Storm, Gert; Hennink, Wim E

2010-12-15

N,N,N-Trimethylated chitosan (TMC) is a biodegradable polymer emerging as a promising nonviral vector for nucleic acid and protein delivery. In the present study, we investigated whether the introduction of thiol groups in TMC enhances the extracellular stability of the complexes based on this polymer and promotes the intracellular release of siRNA. The gene silencing activity and the cellular cytotoxicity of polyplexes based on thiolated TMC were compared with those based on the nonthiolated counterpart and the regularly used lipidic transfection agent Lipofectamine. Incubation of H1299 human lung cancer cells expressing firefly luciferase with siRNA/thiolated TMC polyplexes resulted in 60-80% gene silencing activity, whereas complexes based on nonthiolated TMC showed less silencing (40%). The silencing activity of the complexes based on Lipofectamine 2000 was about 60-70%. Importantly, the TMC-SH polyplexes retained their silencing activity in the presence of hyaluronic acid, while nonthiolated TMC polyplexes hardly showed any silencing activity, demonstrating their stability against competing anionic macromolecules. Under the experimental conditions tested, the cytotoxicity of the thiolated and nonthiolated siRNA complexes was lower than those based on Lipofectamine. Given the good extracellular stability and good silencing activity, it is concluded that polyplexes based on TMC-SH are attractive systems for further in vivo evaluations.

Comparison of cadmium adsorption onto chitosan and epichlorohydrin crosslinked chitosan/eggshell composite

NASA Astrophysics Data System (ADS)

Rahmi; Marlina; Nisfayati

2018-05-01

The use of chitosan and epichlorohydrin crosslinked chitosan/eggshell composite for cadmium adsorption from water were investigated. The factors affecting adsorption such as pH and contact time were considered. The results showed that the optimum pH of adsorption was pH = 6.0 and the equilibrium time of adsorption was 40 min. The adsorption isotherm of Cd ions onto chitosan and composite were well fitted to Langmuir equation. The maximum adsorption capacity (fitting by Langmuir model) of chitosan and composite were 1.008 and 11.7647 mg/g, respectively. Adsorption performance of composite after regeneration was better than chitosan.

Gallium(III) complexes of NOTA-bis (phosphonate) conjugates as PET radiotracers for bone imaging.

PubMed

Holub, Jan; Meckel, Marian; Kubíček, Vojtěch; Rösch, Frank; Hermann, Petr

2015-01-01

Ligands with geminal bis(phosphonic acid) appended to 1,4,7-triazacyclonone-1,4-diacetic acid fragment through acetamide (NOTAM(BP) ) or methylenephosphinate (NO2AP(BP) ) spacers designed for (68) Ga were prepared. Ga(III) complexation is much faster for ligand with methylenephosphinate spacer than that with acetamide one, in both chemical (high reactant concentrations) and radiolabeling studies with no-carrier-added (68) Ga. For both ligands, formation of Ga(III) complex was slower than that with NOTA owing to the strong out-of-cage binding of bis(phosphonate) group. Radiolabeling was efficient and fast only above 60 °C and in a narrow acidity region (pH ~3). At higher temperature, hydrolysis of amide bond of the carboxamide-bis(phosphonate) conjugate was observed during complexation reaction leading to Ga-NOTA complex. In vitro sorption studies confirmed effective binding of the (68) Ga complexes to hydroxyapatite being comparable with that found for common bis(phosphonate) drugs such as pamindronate. Selective bone uptake was confirmed in healthy rats by biodistribution studies ex vivo and by positron emission tomography imaging in vivo. Bone uptake was very high, with SUV (standardized uptake value) of 6.19 ± 1.27 for [(68) Ga]NO2AP(BP) ) at 60 min p.i., which is superior to uptake of (68) Ga-DOTA-based bis(phosphonates) and [(18) F]NaF reported earlier (SUV of 4.63 ± 0.38 and SUV of 4.87 ± 0.32 for [(68) Ga]DO3AP(BP) and [(18) F]NaF, respectively, at 60 min p.i.). Coincidently, accumulation in soft tissue is generally low (e.g. for kidneys SUV of 0.26 ± 0.09 for [(68) Ga]NO2AP(BP) at 60 min p.i.), revealing the new (68) Ga complexes as ideal tracers for noninvasive, fast and quantitative imaging of calcified tissue and for metastatic lesions using PET or PET/CT. Copyright © 2014 John Wiley & Sons, Ltd.

29 CFR 1926.1152 - Methylene chloride.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 8 2012-07-01 2012-07-01 false Methylene chloride. 1926.1152 Section 1926.1152 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Methylene chloride. Note: The requirements applicable to construction employment under this section are...

29 CFR 1926.1152 - Methylene chloride.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 8 2013-07-01 2013-07-01 false Methylene chloride. 1926.1152 Section 1926.1152 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Methylene chloride. Note: The requirements applicable to construction employment under this section are...

29 CFR 1915.1052 - Methylene chloride.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 7 2012-07-01 2012-07-01 false Methylene chloride. 1915.1052 Section 1915.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... § 1915.1052 Methylene chloride. Note: The requirements applicable to shipyard employment under this...

29 CFR 1915.1052 - Methylene chloride.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 7 2011-07-01 2011-07-01 false Methylene chloride. 1915.1052 Section 1915.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... § 1915.1052 Methylene chloride. Note: The requirements applicable to shipyard employment under this...

29 CFR 1915.1052 - Methylene chloride.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 7 2013-07-01 2013-07-01 false Methylene chloride. 1915.1052 Section 1915.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... § 1915.1052 Methylene chloride. Note: The requirements applicable to shipyard employment under this...

29 CFR 1926.1152 - Methylene chloride.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 8 2014-07-01 2014-07-01 false Methylene chloride. 1926.1152 Section 1926.1152 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Methylene chloride. Note: The requirements applicable to construction employment under this section are...

29 CFR 1926.1152 - Methylene chloride.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 8 2011-07-01 2011-07-01 false Methylene chloride. 1926.1152 Section 1926.1152 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Methylene chloride. Note: The requirements applicable to construction employment under this section are...

29 CFR 1915.1052 - Methylene chloride.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 7 2014-07-01 2014-07-01 false Methylene chloride. 1915.1052 Section 1915.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... § 1915.1052 Methylene chloride. Note: The requirements applicable to shipyard employment under this...

29 CFR 1926.1152 - Methylene chloride.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Methylene chloride. 1926.1152 Section 1926.1152 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Methylene chloride. Note: The requirements applicable to construction employment under this section are...

29 CFR 1915.1052 - Methylene chloride.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 7 2010-07-01 2010-07-01 false Methylene chloride. 1915.1052 Section 1915.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... § 1915.1052 Methylene chloride. Note: The requirements applicable to shipyard employment under this...

Preliminary assessment of developmental toxicity of Perfluorinated Phosphonic Acid in mice

EPA Science Inventory

Perfluorinated phosphonic acids (PFPAs) are a third member of the perfluoroalkyl acid (PFAA) family, and are structurally similar to the perfluoroalkyl sulfonates and perfluoroalkyl carboxylates. These emerging chemicals have recently been detected in the environment, particularl...

Preparation and Characterization of Facilitated Transport Membranes Composed of Chitosan-Styrene and Chitosan-Acrylonitrile Copolymers Modified by Methylimidazolium Based Ionic Liquids for CO2 Separation from CH4 and N2

PubMed Central

Otvagina, Ksenia V.; Mochalova, Alla E.; Sazanova, Tatyana S.; Petukhov, Anton N.; Moskvichev, Alexandr A.; Vorotyntsev, Andrey V.; Afonso, Carlos A. M.; Vorotyntsev, Ilya V.

2016-01-01

CO2 separation was found to be facilitated by transport membranes based on novel chitosan (CS)–poly(styrene) (PS) and chitosan (CS)–poly(acrylonitrile) (PAN) copolymer matrices doped with methylimidazolium based ionic liquids: [bmim][BF4], [bmim][PF6], and [bmim][Tf2N] (IL). CS plays the role of biodegradable film former and selectivity promoter. Copolymers were prepared implementing the latest achievements in radical copolymerization with chosen monomers, which enabled the achievement of outstanding mechanical strength values for the CS-based membranes (75–104 MPa for CS-PAN and 69–75 MPa for CS-PS). Ionic liquid (IL) doping affected the surface and mechanical properties of the membranes as well as the gas separation properties. The highest CO2 permeability 400 Barrers belongs to CS-b-PS/[bmim][BF4]. The highest selectivity α (CO2/N2) = 15.5 was achieved for CS-b-PAN/[bmim][BF4]. The operational temperature of the membranes is under 220 °C. PMID:27294964

Stereoselective synthesis of the 5'-hydroxy-5'-phosphonate derivatives of cytidine and cytosine arabinoside.

PubMed

Chen, Xuemei; Wiemer, Andrew J; Hohl, Raymond J; Wiemer, David F

2002-12-27

Both the (R)- and (S)-5'-hydroxy 5'-phosphonate derivatives of cytidine and cytosine arabinoside (ara-C) have been prepared via phosphite addition or a Lewis acid mediated hydrophosphonylation of appropriately protected 5'-nucleoside aldehydes. Phosphite addition to a cytosine aldehyde protected as the 2',3'-acetonide gave predominately the 5'R isomer, while phosphite addition to the corresponding 2',3'-bis TBS derivative favored the 5'S stereochemistry. In contrast, phosphite addition to the 2',3'-bis TBS protected aldehyde derived from ara-C gave only the 5'R adduct. However, TiCl(4)-mediated hydrophosphonylation of the same ara-C aldehyde favored the 5'S stereoisomer by a 2:1 ratio. Once all four of the diastereomers were in hand, the stereochemistry of these compounds could be assigned based on their spectral data or that obtained from their O-methyl mandelate derivatives. After hydrolysis of the phosphonate esters and various protecting groups, the four alpha-hydroxy phosphonic acids were tested for their ability to serve as substrates for the enzyme nucleoside monophosphate kinase and for their toxicity to K562 cells.

HDPE/Chitosan Blends Modified with Organobentonite Synthesized with Quaternary Ammonium Salt Impregnated Chitosan

PubMed Central

de Araújo, Maria José G.; Barbosa, Rossemberg C.; Fook, Marcus Vinícius L.; Canedo, Eduardo L.; Silva, Suédina M. L.; Medeiros, Eliton S.; Leite, Itamara F.

2018-01-01

In this study, blends based on a high density polyethylene (HDPE) and chitosan (CS) were successfully prepared by melt processing, in a laboratory internal mixer. The CS biopolymer content effect (up to maximum of 40%), and, the addition of bentonite clay modified with quaternary ammonium salt (CTAB) impregnated chitosan as a compatibilizing agent, on the properties of the blends was analyzed by Fourier transform-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, and scanning electron microscopy (SEM). The use of clay modified with CTAB impregnated chitosan, employing a method developed here, improved the compatibility of HDPE with chitosan, and therefore the thermal and some of the mechanical properties were enhanced, making HDPE/chitosan blends suitable candidates for food packaging. It was possible to obtain products of synthetic polymer, HDPE, with natural polymer, chitosan, using a method very used industrially, with acceptable and more friendly properties to the environment, when compared to conventional synthetic polymers. In addition, due to the possibility of impregnated chitosan with quaternary ammonium salt exhibit higher antibacterial activity than neat chitosan, the HDPE/chitosan/organobentonite blends may be potentially applied in food containers to favor the preservation of food for a longer time in comparison to conventional materials. PMID:29438286

HDPE/Chitosan Blends Modified with Organobentonite Synthesized with Quaternary Ammonium Salt Impregnated Chitosan.

PubMed

de Araújo, Maria José G; Barbosa, Rossemberg C; Fook, Marcus Vinícius L; Canedo, Eduardo L; Silva, Suédina M L; Medeiros, Eliton S; Leite, Itamara F

2018-02-13

In this study, blends based on a high density polyethylene (HDPE) and chitosan (CS) were successfully prepared by melt processing, in a laboratory internal mixer. The CS biopolymer content effect (up to maximum of 40%), and, the addition of bentonite clay modified with quaternary ammonium salt (CTAB) impregnated chitosan as a compatibilizing agent, on the properties of the blends was analyzed by Fourier transform-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, and scanning electron microscopy (SEM). The use of clay modified with CTAB impregnated chitosan, employing a method developed here, improved the compatibility of HDPE with chitosan, and therefore the thermal and some of the mechanical properties were enhanced, making HDPE/chitosan blends suitable candidates for food packaging. It was possible to obtain products of synthetic polymer, HDPE, with natural polymer, chitosan, using a method very used industrially, with acceptable and more friendly properties to the environment, when compared to conventional synthetic polymers. In addition, due to the possibility of impregnated chitosan with quaternary ammonium salt exhibit higher antibacterial activity than neat chitosan, the HDPE/chitosan/organobentonite blends may be potentially applied in food containers to favor the preservation of food for a longer time in comparison to conventional materials.

Effects of Perfluorinated Phosphonic Acid Exposure during pregnancy in the mouse

EPA Science Inventory

Perfluorinated phosphonic acids (PFPAs) are a member of the perfluoroalkyl acid (PFAA) family, and are structurally similar to the perfluoroalkyl sulfonates and perfluoroalkyl carboxylates. These chemicals have recently been detected in the environment, particularly in surface wa...

The targeted behavior of folate-decorated N-succinyl-N'-octyl chitosan evaluated by NIR system in mouse model

NASA Astrophysics Data System (ADS)

Zhu, Hongyan; Deng, Dawei; Chen, Haiyan; Qian, Zhiyu; Gu, Yueqing

2010-11-01

The development of more selective delivery systems for cancer diagnosis and chemotherapy is one of the most important goals of current anticancer research. The purpose of this study is to construct and evaluate the folate-decorated, self-assembled nanoparticles as candidates to deliver near infrared fluorescent dyes into tumors and to investigate the mechanisms underlying the tumor targeting with folate-decorated, self-assembled nanoparticles. Folate-decorated N-succinyl-N'-octyl chitosan (folate-SOC) were synthesized. The chemical modification chitosan could self-assemble into stable micelles in aqueous medium. Micelle size determined by size analysis was around 140 nm in a phosphate-buffered saline (PBS, PH 7.4). Folate-SOC could maintain their structure for up to 15 days in PBS. Near infrared dye ICG-Der-01 as a mode drug was loaded in the micelles, and the entrapment efficiency (EE) and drug loading (DL) were investigated. The targeted behavior of folate-SOC was evaluated by near-infrared fluorescence imaging in vivo on different groups of denuded mice, with A549 or Bel-7402 tumors. The optical imaging results indicated that folated-decorated SOC showed an excellent tumor specificity in Bel-7402 tumor-bearing mice, and weak tumor specificity in A549 tumor bearing mice. We believe that this work can provide insight for the engineering of nanoparticles and be extended to cancer therapy and diagnosis so as to deliver multiple therapeutic agents and imaging probes at high local concentrations.

29 CFR 1910.1052 - Methylene Chloride.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 6 2014-07-01 2013-07-01 true Methylene Chloride. 1910.1052 Section 1910.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1052 Methylene Chloride. This occupational...

29 CFR 1910.1052 - Methylene Chloride.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 6 2013-07-01 2013-07-01 false Methylene Chloride. 1910.1052 Section 1910.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1052 Methylene Chloride. This occupational...

29 CFR 1910.1052 - Methylene Chloride.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 6 2011-07-01 2011-07-01 false Methylene Chloride. 1910.1052 Section 1910.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1052 Methylene Chloride. This occupational...

29 CFR 1910.1052 - Methylene Chloride.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 6 2012-07-01 2012-07-01 false Methylene Chloride. 1910.1052 Section 1910.1052 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1052 Methylene Chloride. This occupational...

Methylene blue inhibits lumefantrine-resistant Plasmodium berghei.

PubMed

Mwangi, Victor Irungu; Mumo, Ruth Mwende; Kiboi, Daniel Muthui; Omar, Sabah Ahmed; Ng'ang'a, Zipporah Waithera; Ozwara, Hastings Suba

2016-06-30

Chemotherapy still is the most effective way to control malaria, a major public health problem in sub-Saharan Africa. The large-scale use of the combination therapy artemether-lumefantrine for malaria treatment in Africa predisposes lumefantrine to emergence of resistance. There is need to identify drugs that can be used as substitutes to lumefantrine for use in combination therapy. Methylene blue, a synthetic anti-methemoglobinemia drug, has been shown to contain antimalarial properties, making it a candidate for drug repurposing. The present study sought to determine antiplasmodial effects of methylene blue against lumefantrine- and pyrimethamine-resistant strains of P. berghei. Activity of methylene blue was assessed using the classical four-day test on mice infected with lumefantrine-resistant and pyrimethamine-resistant P. berghei. A dose of 45 mg/kg/day was effective for testing ED90. Parasitemia and mice survival was determined. At 45 mg/kg/day, methylene blue sustained significant parasite inhibition, over 99%, for at least 6 days post-treatment against lumefantrine-resistant and pyrimethamine-resistant P. berghei (p = 0.0086 and p = 0.0191, respectively). No serious adverse effects were observed. Our results indicate that methylene blue at a concentration of 45 mg/kg/day confers over 99% inhibition against lumefantrine- and pyrimethamine-resistant P. berghei for six days. This shows the potential use methylene blue in the development of antimalarials against lumefantrine- and pyrimethamine-resistant parasites.

Enzymatic degradation of thiolated chitosan.

PubMed

Laffleur, Flavia; Hintzen, Fabian; Rahmat, Deni; Shahnaz, Gul; Millotti, Gioconda; Bernkop-Schnürch, Andreas

2013-10-01

The objective of this study was to evaluate the biodegradability of thiolated chitosans in comparison to unmodified chitosan. Mediated by carbodiimide, thioglycolic acid (TGA) and mercaptonicotinic acid (MNA) were covalently attached to chitosan via formation an amide bond. Applying two different concentrations of carbodiimide 50 and 100 mM, two chitosan TGA conjugates (TGA A and TGA B) were obtained. According to chitosan solution (3% m/v) thiomer solutions were prepared and chitosanolytic enzyme solutions were added. Lysozyme, pectinase and cellulase were examined in chitosan degrading activity. The enzymatic degradability of these thiomers was investigated by viscosity measurements with a plate-plate viscometer. The obtained chitosan TGA conjugate A displayed 267.7 µmol and conjugate B displayed 116.3 µmol of immobilized thiol groups. With 325.4 µmol immobilized thiol groups, chitosan MNA conjugate displayed the most content of thiol groups. In rheological studies subsequently the modification proved that chitosan TGA conjugates with a higher coupling rate of thiol groups were not only degraded to a lesser extent by 20.9-26.4% but also more slowly. Chitosan mercaptonicotinic acid was degraded by 31.4-50.1% depending the investigated enzyme and even faster than unmodified chitosan. According to these results the biodegradability can be influenced by various modifications of the polymer which showed in particular that the rate of biodegradation is increased when MNA is the ligand, whereas the degradation is hampered when TGA is used as ligand for chitosan.

Experimental evaluation of photocrosslinkable chitosan as a biologic adhesive with surgical applications.

PubMed

Ono, K; Ishihara, M; Ozeki, Y; Deguchi, H; Sato, M; Saito, Y; Yura, H; Sato, M; Kikuchi, M; Kurita, A; Maehara, T

2001-11-01

In various surgical cases, effective tissue adhesives are required for both hemostasis (eg, intraoperative bleeding) and air sealing (eg, thoracic surgery). We have designed a chitosan molecule (Az-CH-LA) that can be photocrosslinked by ultraviolet (UV) light irradiation, thereby forming a hydrogel. The purpose of this work was to evaluate the effectiveness and safety of the photocrosslinkable chitosan hydrogel as an adhesive with surgical applications. The sealing ability of the chitosan hydrogel, determined as a bursting pressure, was assessed with removed thoracic aorta, trachea, and lung of farm pigs and in a rabbit model. The carotid artery and lung of rabbits were punctured with a needle, and the chitosan hydrogel was applied to, respectively, stop the bleeding and the air leakage. In vivo chitosan degradability and biologic responses were histologically assessed in animal models. The bursting pressure of chitosan hydrogel (30 mg/mL) and fibrin glue, respectively, was 225 +/- 25 mm Hg (mean +/- SD) and 80 +/- 20 mm Hg in the thoracic aorta; 77 +/- 29 mm Hg and 48 +/- 21 mm Hg in the trachea; and in the lung, 51 +/- 11 mm Hg (chitosan hydrogel), 62 +/- 4 mm Hg (fibrin glue, rubbing method), and 12 +/- 2 mm Hg (fibrin glue, layer method). The sealing ability of the chitosan hydrogel was stronger than that of fibrin glue. All rabbits with a carotid artery (n = 8) or lung (n = 8) that was punctured with a needle and then sealed with chitosan hydrogel survived the 1-month observation period without any bleeding or air leakage from the puncture sites. Histologic examinations demonstrated that 30 days after application, a fraction of the chitosan hydrogel was phagocytosed by macrophages, had partially degraded, and had induced the formation of fibrous tissues around the hydrogel. A newly developed photocrosslinkable chitosan has demonstrated strong sealing ability and a great potential for use as an adhesive in surgical operations.

Optimizing deacetylation process for chitosan production from green mussel (perna viridis) shell

NASA Astrophysics Data System (ADS)

Danarto, Y. C.; Distantina, Sperisa

2016-02-01

The green mussel (perna viridis) shell waste could be utilized for chitosan production because it contained chitin. Chitin can be derived into chitosan through the deacetylation process. Chitosan is a polysaccharides polymer that is readily soluble in dilute acid solution and easily modified into other useful compounds. This research aimed to study the chitosan production from green mussel shells. This experiment had the following stages, deproteinization process aimed to eliminate the protein content using 1N NaOH solution, demineralization process aimed to remove minerals in green mussel shells as CaCO3 using 1 N HCl solution and decolorization process aimed to eliminate the color pigments and other impurities using ethanol solvent. All process above resulted chitin. Furthermore, chemical modification of chitin into chitosan by deacetylation process. This stage was very important because it greatly affected the chitosan properties. This research studied two different treatment for deacetylation process. The first treatment was the deacetylation process using concentrated NaOH solution (50% w), at high temperatures (90 - 100 °C) for 2 hours extraction, whilw the second treatment was deacetylation process using a low concentration of NaOH solution (15% w), at room temperature for 24 hours. The results showed that deproteinization, demineralization, and decolorizaton was capable of removing protein, mineral, and pigment. This experiment yield chitin 41.6 %wt. Chitosan yield from second treatment was 39.5%w and it was better than first treatment. Chitosan from first treatment had 79.8% degree of deacetylation and 16.5 kDa molecular weight. It was better than first treatment.

Oxidation-mediated chitosan as additives for creation of chitosan aerogels with diverse three-dimensional interconnected skeletons

NASA Astrophysics Data System (ADS)

Zhang, Sizhao; Feng, Jian; Feng, Junzong; Jiang, Yonggang

2017-02-01

Naturally occurring polymer-based aerogels have myriad practical utilizations due to environmentally benign and fruitful resources. However, engineering morphology-controllable biomass aerogels still represents a great challenge. Here we present a facile solution to synthesize chitosan aerogels having distinguished textures by reacting oxidized chitosan with formaldehyde and chitosan sol. In more detail, chitosan was chemically oxidized using two types of oxidation agents such as ammonium persulphate (SPD) and sodium periodate (APS) to obtain corresponding oxidized chitosan, subsequently cross-linked with chitosan solution containing formaldehyde to harvest SPD-oxidized chitosan aerogels (SCAs) and APS-SPD-oxidized ones (ASCAs) after aging, solvent exchange and supercritical drying processes. We found that the morphologies of as-prepared chitosan aerogels are strongly dependent upon the oxidation pattern towards chitosan. The structural textures of SCAs and ASCAs appear nanoflake-like and nanofiber-like structures, which may be related to spatial freedom of active groups located in chitosan. Selected area electron diffraction analysis reveals that the crystalline properties of chitosan aerogels generally appear the serious deterioration comparing to raw chitosan owing to their interconnected skeletal structure formation. The occurrence of characteristic groups displays cross-linked chain construction by using chemical state measurements such as FT-IR and XPS. Further, a plausible mechanism for controlling morphology of chitosan aerogels is also established. This new family of method for creation of chitosan aerogels may open up a perspective for biomass aerogels with controllable textures.

Development of silver/titanium dioxide/chitosan adipate nanocomposite as an antibacterial coating for fruit storage

USDA-ARS?s Scientific Manuscript database

A novel nanocomposite of silver/titanium dioxide/chitosan adipate (Ag/TiO2/CS) was developed through photochemical reduction using a chitosan adipate template. Chitosan served as a reducing agent for the metal ions, and anchored metal ions by forming Ag–N coordination bonds and electrostatic attract...

Effect of chitosan content on gel content of epoxized natural rubber grafted with chitosan in latex form.

PubMed

Riyajan, Sa-Ad; Sukhlaaied, Wattana

2013-04-01

The epoxidized natural rubber (ENR) latex-g-chitosan (ENR-g-chitosan) was prepared in latex form using potassium persulphate as an initiator. Firstly, the reduction in molecular weight of chitosan was subjected to the addition of K2S2O8 at 70 °C for 15 min. The structure of the modified chitosan was characterized by ATR-FTIR. Secondarily, the influence of chitosan contents, reaction time, and temperature and K2S2O8 concentrations on the gel content of the modified ENR was investigated. The chemical structure of the ENR-g-chitosan was confirmed by (1)H-NMR and ATR-FTIR. The ether linkage of the ENR-g-chitosan was conformed at 1154 an 1089 cm(-1) by ATR-FTIR and 3.60 ppm by (1)H-NMR. The gel content of ENR-g-chitosan at 5% chitosan showed the highest value compared with other samples. But when chitosan increased from 5% to 10% or 20%, the gel content of ENR-g-chitosan dramatically decreased. The ENR-g-chitosan showed good thermal resistance due to incorporation of chitosan. The morphology of ENR-g-chitosan particle showed the core-shell structure observed by TEM. The optimum condition of grafting ENR with chitosan was found at 65°C for 3h of reaction time, ratio of ENR/chitosan at 9:1. Copyright © 2012 Elsevier B.V. All rights reserved.

Methylene blue induced morphological deformations in Plasmodium falciparum gametocytes: implications for transmission-blocking.

PubMed

Wadi, Ishan; Pillai, C Radhakrishna; Anvikar, Anupkumar R; Sinha, Abhinav; Nath, Mahendra; Valecha, Neena

2018-01-08

Malaria remains a global health problem despite availability of effective tools. For malaria elimination, drugs targeting sexual stages of Plasmodium falciparum need to be incorporated in treatment regimen along with schizonticidal drugs to interrupt transmission. Primaquine is recommended as a transmission blocking drug for its effect on mature gametocytes but is not extensively utilized because of associated safety concerns among glucose-6-phosphate dehydrogenase (G6PD) deficient patients. In present work, methylene blue, which is proposed as an alternative to primaquine is investigated for its gametocytocidal activity amongst Indian field isolates. An effort has been made to establish Indian field isolates of P. falciparum as in vitro model for gametocytocidal drugs screening. Plasmodium falciparum isolates were adapted to in vitro culture and induced to gametocyte production by hypoxanthine and culture was enriched for gametocyte stages using N-acetyl-glucosamine. Gametocytes were incubated with methylene blue for 48 h and stage specific gametocytocidal activity was evaluated by microscopic examination. Plasmodium falciparum field isolates RKL-9 and JDP-8 were able to reproducibly produce gametocytes in high yield and were used to screen gametocytocidal drugs. Methylene blue was found to target gametocytes in a concentration dependent manner by either completely eliminating gametocytes or rendering them morphologically deformed with mean IC 50 (early stages) as 424.1 nM and mean IC 50 (late stages) as 106.4 nM. These morphologically altered gametocytes appeared highly degenerated having shrinkage, distortions and membrane deformations. Field isolates that produce gametocytes in high yield in vitro can be identified and used to screen gametocytocidal drugs. These isolates should be used for validation of gametocytocidal hits obtained previously by using lab adapted reference strains. Methylene blue was found to target gametocytes produced from Indian field

In vivo assessment of chitosan/β-glycerophosphate as a new liquid embolic agent.

PubMed

Wang, Y; Xu, N; Luo, Q; Li, Y; Sun, L; Wang, H; Xu, K; Wang, B; Zhen, Y

2011-03-01

We sought to assess the feasibility of using thermosensitive chitosan/β-glycerophosphate forembolotherapy. The renal arteries in nine rabbits were embolized with chitosan/β-glycero-phosphate. The animals were studied angiographically and sacrificed at one week (n = 3), four weeks (n = 3), and eight weeks (n = 3) after embolotherapy. Histology was obtained at these three time points. Delivery of chitosan/β-glycerophosphate was successful in all cases. Complete occlusion was achieved in all cases. No recanalization was observed in the follow-up angiograms. No untoward inflammatory reactions were observed in the target renal arteries and infarcted kidneys during the histological examinations. Our preliminary feasibility evaluation in rabbit renal arteries indicates that C/GP is a satisfactory embolization agent.

Synthesis and characterization of N-(2-hydroxy)propyl-3-trimethyl ammonium chitosan chloride for potential application in gene delivery.

PubMed

Xiao, Bo; Wan, Ying; Wang, Xiaoyu; Zha, Qichen; Liu, Haoming; Qiu, Zhiye; Zhang, Shengmin

2012-03-01

A series of N-(2-hydroxy)propyl-3-trimethyl ammonium chitosan chloride (HTCC) samples with various degrees of quaternization ranging from 12.4 to 43.7% was synthesized. The structures and properties of HTCC were investigated by FT-IR, (1)H NMR, conductometric titration and XRD analysis. It was found that HTCC had a more amorphous structure than chitosan. HTCC samples showed significantly lower cytotoxicity than polyethyleneimine in HepG2 and HeLa cell lines. The samples spontaneously formed complexes with pGL3 luciferase plasmid. These complexes had desirable particle sizes (160-300 nm) and zeta potentials (10.8-18.7 mV) when the weight ratios of HTCC to plasmid altered in the range of 3:1-20:1. In vitro gene transfection results indicated that HTCC had significantly high transfection efficiency compared with chitosan for delivering pGL3 luciferase plasmid to HeLa cells. The results suggest that HTCC could be a promising non-viral vector for safe and efficient DNA delivery. Copyright © 2011 Elsevier B.V. All rights reserved.

DEGRADATION OF NITRILOTRIS (METHYLENEPHOSPHONIC ACID) AND RELATED (AMINO) PHOSPHONATE CHELATING AGENTS IN THE PRESENCE OF MANGANESE AND MOLECULAR OXYGEN. (R826376)

EPA Science Inventory

Phosphonates are used in an increasing variety of industrial and household
applications including cooling waters systems, oil production, textile industry,
and detergents. Phosphonates are not biodegraded during wastewater treatment but
instead are removed by adsor...

Influence of chitosan concentration on mechanical and barrier properties of corn starch/chitosan films.

PubMed

Ren, Lili; Yan, Xiaoxia; Zhou, Jiang; Tong, Jin; Su, Xingguang

2017-12-01

The active packaging films based on corn starch and chitosan were prepared through mixing the starch solution and the chitosan solution (1:1) by casting. The aim of this work was to characterize and analyze the effects of the chitosan concentrations (0, 21, 41, 61 and 81wt% of starch) on physicochemical, mechanical and water vapor barrier properties as well as morphological characteristics of the corn starch/chitosan (CS/CH) films. Starch molecules and chitosan could interact through hydrogen bonding as confirmed from the shift of the main peaks to higher wavenumbers in FTIR and the reduction of crystallinity in XRD. Results showed that the incorporation of chitosan resulted in an increase in film solubility, total color differences, tensile strength and elongation at break and a decrease in Young's modulus and water vapor permeability (WVP). Elongation at break of the CS/CH films increased with increasing of chitosan concentration, and reached a maximum at 41 wt%, then declined at higher chitosan concentration. The WVP of CS/CH films increased with an increase of chitosan concentration and the same tendency observed for the moisture content. The results suggest that this biodegradable CS/CH films could potentially be used as active packaging films for food and pharmaceutical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of Chitin and Chitosan Molecular Structure in Aqueous Solution

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

Franca, Eduardo D.; Lins, Roberto D.; Freitas, Luiz C.

Molecular dynamics simulations have been used to characterize the structure of chitin and chitosan fibers in aqueous solutions. Chitin fibers, whether isolated or in the form of a β-chitin nanoparticle, adopt the so-called 2-fold helix with Φ and φ values similar to its crystalline state. In solution, the intramolecular hydrogen bond HO3(n)•••O5(n+1) responsible for the 2-fold helical motif is stabilized by hydrogen bonds with water molecules in a well-defined orientation. On the other hand, chitosan can adopt five distinct helical motifs and its conformational equilibrium is highly dependent on pH. The hydrogen bond pattern and solvation around the O3 atommore » of insoluble chitosan (basic pH) are nearly identical to these quantities in chitin. Our findings suggest that the solubility and conformation of these polysaccharides are related to the stability of the intrachain HO3(n)•••O5(n+1) hydrogen bond, which is affect by the water exchange around the O3-HO3 hydroxyl group.« less

Intranasal delivery of cyclobenzaprine hydrochloride-loaded thiolated chitosan nanoparticles for pain relief.

PubMed

Patel, Deepa; Naik, Sachin; Chuttani, Krishna; Mathur, Rashi; Mishra, Anil K; Misra, Ambikanandan

2013-09-01

The purpose of present investigation was to formulate and characterize the cyclobenzaprine HCl (CBZ)-loaded thiolated chitosan nanoparticles and assessment of in-vitro cell viability, trans-mucosal permeability on RPMI2650 cell monolayer, in-vivo pharmacokinetic and pharmacodynamic study of thiolated chitosan nanoparticles on Swiss albino mice after intranasal administration. A significant high permeation of drug was observed from thiolated chitosan nanoparticles with less toxicity on nasal epithelial cells. Brain uptake of the drug after (99m)Tc labeling was significantly enhanced after thiolation of chitosan. CBZ-loaded thiolated chitosan NPs significantly reverse the N-Methyl-.-Aspartate (NMDA)-induced hyperalgesia by intranasal administration than the CBZ solution. The studies of present investigation revealed that thiolation of chitosan significantly reduce trans-mucosal toxicity with enhanced trans-mucosal permeability via paracellular pathway and brain uptake of a hydrophilic drug (normally impermeable across blood brain barrier) and pain alleviation activity via intranasal route.

Chitosan coated carbon fiber microelectrode for selective in vivo detection of neurotransmitters in live zebrafish embryos

PubMed Central

Özel, Rıfat Emrah; Wallace, Kenneth N.; Andreescu, Silvana

2011-01-01

We report the development of a chitosan modified carbon fiber microelectrode for in vivo detection of serotonin. We find that chitosan has the ability to reject physiological levels of ascorbic acid interferences and facilitate selective and sensitive detection of in vivo levels of serotonin, a common catecholamine neurotransmitter. Presence of chitosan on the microelectrode surface was investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrode was characterized using differential pulse voltammetry (DPV). A detection limit of 1.6 nM serotonin with a sensitivity of 5.12 nA/µM, a linear range from 2 to 100 nM and a reproducibility of 6.5 % for n=6 electrodes were obtained. Chitosan modified microelectrodes selectively measure serotonin in presence of physiological levels of ascorbic acid. In vivo measurements were performed to measure concentration of serotonin in the live embryonic zebrafish intestine. The sensor quantifies in vivo intestinal levels of serotonin while successfully rejecting ascorbic acid interferences. We demonstrate that chitosan can be used as an effective coating to reject ascorbic acid interferences at carbon fiber microelectrodes, as an alternative to Nafion, and that chitosan modified microelectrodes are reliable tools for in vivo monitoring of changes in neurotransmitter levels. PMID:21601035

The mechanism of action of piperazine-phosphonates derivatives in cotton fabric

USDA-ARS?s Scientific Manuscript database

Piperazine-phosphonates additives are known to be very effective flame retardants on different polymeric systems, especially cotton cellulose. In order to understand their mechanism of action, we carried out the investigation of their thermal behavior on cotton fabric by, first, employing the attenu...

Transfection efficiency of chitosan and thiolated chitosan in retinal pigment epithelium cells: A comparative study

PubMed Central

Oliveira, Ana V.; Silva, Andreia P.; Bitoque, Diogo B.; Silva, Gabriela A.; Rosa da Costa, Ana M.

2013-01-01

OBJECTIVE: Gene therapy relies on efficient vector for a therapeutic effect. Efficient non-viral vectors are sought as an alternative to viral vectors. Chitosan, a cationic polymer, has been studied for its gene delivery potential. In this work, disulfide bond containing groups were covalently added to chitosan to improve the transfection efficiency. These bonds can be cleaved by cytoplasmic glutathione, thus, releasing the DNA load more efficiently. MATERIALS AND METHODS: Chitosan and thiolated chitosan nanoparticles (NPs) were prepared in order to obtain a NH3+:PO4− ratio of 5:1 and characterized for plasmid DNA complexation and release efficiency. Cytotoxicity and gene delivery studies were carried out on retinal pigment epithelial cells. RESULTS: In this work, we show that chitosan was effectively modified to incorporate a disulfide bond. The transfection efficiency of chitosan and thiolated chitosan varied according to the cell line used, however, thiolation did not seem to significantly improve transfection efficiency. CONCLUSION: The apparent lack of improvement in transfection efficiency of the thiolated chitosan NPs is most likely due to its size increase and charge inversion relatively to chitosan. Therefore, for retinal cells, thiolated chitosan does not seem to constitute an efficient strategy for gene delivery. PMID:23833516

Photochemical tissue bonding with chitosan adhesive films

PubMed Central

2010-01-01

Background Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Methods Adhesive films, based on chitosan and containing ~0.1 wt% RB were manufactured and bonded to calf intestine by a solid state laser (λ = 532 nm, Fluence~110 J/cm2, spot size~0.5 cm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results The RB-chitosan adhesive bonded firmly to the intestine with adhesion strength of 15 ± 2 kPa, (n = 31). The adhesion strength dropped to 0.5 ± 0.1 (n = 8) kPa when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26°C to 32°C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. Conclusion A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase. PMID:20825632

Methylene Chloride.

PubMed

Phillips, Jennan A

2018-02-01

Methylene chloride is an industrial solvent used in commercial paint strippers and degreasing agents. This chemical is widely used in consumer products, yet without appropriate protections, exposure may lead to death. Already banned in some countries, the Environmental Protection Agency (EPA) recently proposed limiting its use in the United States.

Improvement in hemocompatibility of chitosan/soy protein composite membranes by heparinization.

PubMed

Wang, Xiaomei; Shi, Na; Chen, Yan; Li, Chen; Du, Xinshen; Jin, Weihua; Chen, Yun; Chang, Peter R

2012-01-01

To improve the hemocompatibility of chitosan/soy protein isolate composite membranes by heparinization. Chitosan/soy protein isolate membranes (ChS-n, n=0, 10 and 30, corresponding to the soy protein isolate content in the membranes) and heparinized ChS-n membranes (HChS-n) were prepared by blending in dilute HAc/NaAc solution. The hemocompatibility of ChS-n and HChS-n membranes were comparatively evaluated by measuring surface heparin density, blood platelet adhesion, plasma recalcification time (PRT), thrombus formation and hemolysis assay. The surface heparin density analysis showed that heparinized chitosan/SPI soy protein isolate membranes have been successfully prepared by blending. The density of heparin on the surface of HChS-n membranes was in the range of 0.67-1.29 μg/cm2. The results of platelet adhesion measurement showed that the platelet adhesion numbers of HChS-n membranes were lower than those of the corresponding ChS-n membranes. The PRT of the HChS-0, HChS-10 and HChS-30 membranes were around 292, 306 and 295 s, respectively, which were longer than the corresponding ChS-0 (152 s), ChS-10 (204 s) and ChS-30 (273 s) membranes. The hemolysis rate of HChS-n membranes was lower than 1%. The hemocompatibility of ChS membranes could be improved by blending with heparin. Compared with ChS membranes, HChS membranes showed lower platelet adhesion, longer PRT, higher BCI, significant thromboresistivity and a lower hemolysis rate due to the heparinization. This widens the application of chitosan and soy protein-based biomaterials that may come in contact with blood.

Preparation of polyvinyl alcohol graphene oxide phosphonate film and research of thermal stability and mechanical properties.

PubMed

Li, Jihui; Song, Yunna; Ma, Zheng; Li, Ning; Niu, Shuai; Li, Yongshen

2018-05-01

In this article, flake graphite, nitric acid, peroxyacetic acid and phosphoric acid are used to prepare graphene oxide phosphonic and phosphinic acids (GOPAs), and GOPAs and polyvinyl alcohol (PVA) are used to synthesize polyvinyl alcohol graphene oxide phosphonate and phosphinate (PVAGOPs) in the case of faint acidity and ultrasound irradiation, and PVAGOPs are used to fabricate PVAGOPs film, and the structure and morphology of GOPAs, PVAGOPs and PVAGOPs film are characterized, and the thermal stability and mechanical properties of PVAGOPs film are investigated. Based on these, it has been proved that GOPAs consist of graphene oxide phosphonic acid and graphene oxide phosphinic acid, and there are CP covalent bonds between them, and PVAGOPs are composed of GOPAs and PVA, and there are six-member lactone rings between GOPAs and PVA, and the thermal stability and mechanical properties of PVAGOPs film are improved effectively. Copyright © 2018 Elsevier B.V. All rights reserved.

The dispersion of fine chitosan particles by beads-milling

NASA Astrophysics Data System (ADS)

Rochima, Emma; Utami, Safira; Hamdani, Herman; Azhary, Sundoro Yoga; Praseptiangga, Danar; Joni, I. Made; Panatarani, Camellia

2018-02-01

This research aimed to produce fine chitosan particles from a crab shell waste by beads-milling method by two different concentration of PEG as dispersing agent (150 and 300 wt. %). The characterization was performed to obtain the size and size distribution, the characteristics of functional groups and the degree of deacetylation. The results showed that the chitosan fine particles was obtained with a milling time 120 minutes with the best concentration of PEG 400 150 wt. %. The average particle size of the as-prepared suspension is 584 nm after addition of acetic acid solution (1%, v/v). Beads milling process did not change the glucosamine and N-acetylglucosamine content on chitosan structure which is indicated by degree of deacetylation higher than 70%. It was concluded that beads milling process can be applied to prepare chitosan fineparticles by proper adjustment in the milling time, pH and dosage of dispersing agent.

In Vivo Assessment of Chitosan/ β-Glycerophosphate as a New Liquid Embolic Agent

PubMed Central

Wang, Y.; Xu, N.; Luo, Q.; Li, Y.; Sun, L.; Wang, H.; Xu, K.; Wang, B.; Zhen, Y.

2011-01-01

Summary We sought to assess the feasibility of using thermosensitive chitosan/β-glycerophosphate for embolotherapy. The renal arteries in nine rabbits were embolized with chitosan/β-glycerophosphate. The animals were studied angiographically and sacrificed at one week (n = 3), four weeks (n = 3), and eight weeks (n = 3) after embolotherapy. Histology was obtained at these three time points. Delivery of chitosan/β-glycerophosphate was successful in all cases. Complete occlusion was achieved in all cases. No recanalization was observed in the follow-up angiograms. No untoward inflammatory reactions were observed in the target renal arteries and infarcted kidneys during the histological examinations. Our preliminary feasibility evaluation in rabbit renal arteries indicates that C/GP is a satisfactory embolization agent. PMID:21561564

Two-Ply Composite Membranes with Separation Layers from Chitosan and Sulfoethylcellulose on a Microporous Support Based on Poly(diphenylsulfone-N-phenylphthalimide).

PubMed

Kononova, Svetlana V; Kruchinina, Elena V; Petrova, Valentina A; Baklagina, Yulia G; Romashkova, Kira A; Orekhov, Anton S; Klechkovskaya, Vera V; Skorik, Yury A

2017-12-14

Two-ply composite membranes with separation layers from chitosan and sulfoethylcellulose were developed on a microporous support based on poly(diphenylsulfone- N -phenylphthalimide) and investigated by use of X-ray diffraction and scanning electron microscopy methods. The pervaporation properties of the membranes were studied for the separation of aqueous alcohol (ethanol, propan-2-ol) mixtures of different compositions. When the mixtures to be separated consist of less than 15 wt % water in propan-2-ol, the membranes composed of polyelectrolytes with the same molar fraction of ionogenic groups (-NH₃⁺ for chitosan and -SO₃ - for sulfoethylcellulose) show high permselectivity (the water content in the permeate was 100%). Factors affecting the structure of a non-porous layer of the polyelectrolyte complex formed on the substrate surface and the contribution of that complex to changes in the transport properties of membranes are discussed. The results indicate significant prospects for the use of chitosan and sulfoethylcellulose for the formation of highly selective pervaporation membranes.

Serotonin syndrome following methylene blue administration during cardiothoracic surgery.

PubMed

Smith, Christina J; Wang, Dorothy; Sgambelluri, Anna; Kramer, Robert S; Gagnon, David J

2015-04-01

Despite its favorable safety profile, there have been reports of methylene blue-induced encephalopathy and serotonin syndrome in patients undergoing parathyroidectomy. We report a case of serotonin syndrome following methylene blue administration in a cardiothoracic surgery patient. A 59-year-old woman taking preoperative venlafaxine and trazodone was given a single dose of 2 mg/kg methylene blue (167 mg) during a planned coronary artery bypass and mitral valve repair. Postoperatively, she was febrile to 38.7°C and developed full-body tremors, rhythmic twitching of the perioral muscles, slow conjugate roving eye movements, and spontaneous movements of the upper extremities. Electroencephalography revealed generalized diffuse slowing consistent with toxic encephalopathy, and a computed tomography scan showed no acute process. The patient's symptoms were most consistent with a methylene blue-induced serotonin syndrome. Her motor symptoms resolved within 48 hours and she was eventually discharged home. Only 2 cases of methylene blue-induced serotonin syndrome during cardiothoracic surgery have been described in the literature, with this report representing the third case. Methylene blue and its metabolite, azure B, are potent, reversible inhibitors of monoamine oxidase A which is responsible for serotonin metabolism. Concomitant administration of methylene blue with serotonin-modulating agents may precipitate serotonin syndrome. © The Author(s) 2015.

Physicochemical properties and biocompatibility of N-trimethyl chitosan: effect of quaternization and dimethylation.

PubMed

Jintapattanakit, Anchalee; Mao, Shirui; Kissel, Thomas; Junyaprasert, Varaporn Buraphacheep

2008-10-01

The aim of this research was to investigate the effect of degrees of quaternization (DQ) and dimethylation (DD) on physicochemical properties and cytotoxicity of N-trimethyl chitosan (TMC). TMC was synthesized by reductive methylation of chitosan in the presence of a strong base at elevated temperature and polymer characteristics were investigated. The number of methylation process and duration of reaction were demonstrated to affect the DQ and DD. An increased number of reaction steps increased DQ and decreased DD, while an extended duration of reaction increased both DQ and DD. The molecular weight of TMC was in the range of 60-550kDa. From the Mark-Houwink equation, it was found that TMC in 2% acetic acid/0.2M sodium acetate behaved as a spherical structure, approximating a random coil. The highest solubility was found with TMC of an intermediate DQ (40%) regardless of DD and molecular weight. The effect of DD on the physicochemical properties and cytotoxicity was obviously observed when proportion of DD to DQ was higher than 1. TMC with relatively high DD showed reduction in both solubility and mucoadhesion and hence decreased cytotoxicity. However, the influence of DD was insignificant when DQ of TMC was higher than 40% at which physicochemical properties and cytotoxicity were mainly dependent upon DQ.

The Effects of Phosphonic Acids in Dye-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

James, Keith Edward

Novel methods for the construction of dye-sensitized solar cells (DSSCs) were developed. A thin dense underlayer of TiO2 was applied on fluorine-doped tin oxide (FTO) glass using as a precursor Tyzor AA-105. Subsequently a mesoporous film of P-25 TiO2 was applied by spreading a suspension uniformly over the surface of the underlayer and allowing the plate to slowly dry while resting on a level surface. After sintering at 500° C slides were treated with TCPP as a sensitizing dye and assembled into DSSCs. A novel method was used to seal the cells; strips of ParafilmRTM were used as spacers between the electrodes and to secure the electrodes together. The cells were filled with a redox electrolyte and sealed by dipping into molten paraffin. A series of phosphonic acids and one arsonic acid were employed as coadsorbates in DSSCs. The coadsorbates were found to compete for binding sites, resulting in lower levels of dye adsorption. The resulting loss of photocurrent was not linear with the reduction of dye loading, and in some cases photocurrent and efficiency were higher for cells with lower levels of dye loading. Electrodes were treated with coadsorbates by procedures including pre-adsorption, simultaneous (sim-adsorption), and post-adsorption, using a range of concentrations and treatment times and a variety of solvents. Most cells were tested using an iodide-triiodide based electrolyte (I3I-1) but some cells were tested using electrolytes based on a Co(II)/Co(III) redox couple (CoBpy electrolytes). Phosphonic acid post-adsorbates increased the Voc of cells using CoBpy electrolytes but caused a decrease in the Voc of cells using I3I-1 electrolyte. Phosphonic acids as sim-adsorbates resulted in a significant increase in efficiency and Jsc, and they show promise as a treatment for TCPP DSSCs.

SF2312 is a natural phosphonate inhibitor of Enolase

PubMed Central

Maxwell, David; Lin, Yu-Hsi; Hammoudi, Naima; Peng, Zhenghong; Pisaneschi, Federica; Link, Todd M.; Lee, Gilbert R.; Sun, Duoli; Prasad, Basvoju A. Bhanu; Di Francesco, Maria Emilia; Czako, Barbara; Asara, John M.; Wang, Y. Alan; Bornmann, William; DePinho, Ronald A.; Muller, Florian L.

2016-01-01

Despite being critical for energy generation in most forms of life, few if any microbial antibiotics specifically inhibit glycolysis. To develop a specific inhibitor of the glycolytic enzyme Enolase 2 for the treatment of cancers with deletion of Enolase 1, we modeled the synthetic tool compound inhibitor, Phosphonoacetohydroxamate (PhAH) into the active site of human ENO2. A ring-stabilized analogue of PhAH, with the hydroxamic nitrogen linked to the alpha-carbon by an ethylene bridge, was predicted to increase binding affinity by stabilizing the inhibitor in a bound conformation. Unexpectedly, a structure based search revealed that our hypothesized back-bone-stabilized PhAH bears strong similarity to SF2312, a phosphonate antibiotic of unknown mode of action produced by the actinomycete Micromonospora, which is active under anaerobic conditions. Here, we present multiple lines of evidence, including a novel X-ray structure, that SF2312 is a highly potent, low nM inhibitor of Enolase. PMID:27723749

Blood contact properties of ascorbyl chitosan.

PubMed

Yalinca, Z; Yilmaz, E; Taneri, B; Bullici, F; Tuzmen, S

2013-01-01

Ascorbyl chitosan was synthesized by heating chitosan with ascorbic acid in isopropanol. The products were characterized by FTIR and C-13 NMR spectroscopies, SEM, and elemental analysis. Blood contact properties of ascorbyl chitosans were evaluated. The ascorbyl chitosans demonstrated to have increased lipid-lowering activity in comparison to chitosan alone upon contact with human blood serum in in vitro conditions. Furthermore, the total cholesterol/HDL ratio was improved towards the desirable ideal values after three hours contact with ascorbyl chitosan samples. The lipid-lowering activity increased with ascorbyl substitution. The inherent nonspecific adsorption capability of chitosan due to its chelating power with several different functional groups was exhibited by ascorbyl chitosans as well. This behavior was exemplified in a simultaneous decrease in the total iron values of the volunteers together with lower lipid levels. Furthermore, ascorbyl chitosans were observed to have less hemocompatibility but increased anticoagulant activity when compared to chitosan alone. Additional in vivo studies are necessary to support these results and to investigate further the advantages and disadvantages of these materials to prove their safety prior to clinical applications.

Chitin, Chitosan, and Glycated Chitosan Regulate Immune Responses: The Novel Adjuvants for Cancer Vaccine

PubMed Central

Li, Xiaosong; Min, Min; Du, Nan; Gu, Ying; Hode, Tomas; Naylor, Mark; Chen, Dianjun; Nordquist, Robert E.; Chen, Wei R.

2013-01-01

With the development of cancer immunotherapy, cancer vaccine has become a novel modality for cancer treatment, and the important role of adjuvant has been realized recently. Chitin, chitosan, and their derivatives have shown their advantages as adjuvants for cancer vaccine. In this paper, the adjuvant properties of chitin and chitosan were discussed, and some detailed information about glycated chitosan and chitosan nanoparticles was also presented to illustrate the trend for future development. PMID:23533454

Methylene blue test

MedlinePlus

The methylene blue test is a test to determine the type or to treat methemoglobinemia , a blood disorder. ... higher, you can become sick because the protein is not carrying ... of red. Methemoglobinemia has several causes, many of which are ...

Encapsulation of testosterone by chitosan nanoparticles.

PubMed

Chanphai, P; Tajmir-Riahi, H A

2017-05-01

The loading of testosterone by chitosan nanoparticles was investigated, using multiple spectroscopic methods, thermodynamic analysis, TEM images and modeling. Thermodynamic parameters showed testosterone-chitosan bindings occur mainly via H-bonding and van der Waals contacts. As polymer size increased more stable steroid-chitosan conjugates formed and hydrophobic contact was also observed. The loading efficacy of testosterone-nanocarrier was 40-55% and increased as chitosan size increased. Testosterone encapsulation markedly alters chitosan morphology. Chitosan nanoparticles are capable of transporting testosterone in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Antimicrobial activity of chitosan coatings and films against Listeria monocytogenes on black radish.

PubMed

Jovanović, Gordana D; Klaus, Anita S; Nikšić, Miomir P

2016-01-01

The antibacterial activity of chitosan coatings prepared with acetic or lactic acid, as well as of composite chitosan-gelatin films prepared with essential oils, was evaluated in fresh shredded black radish samples inoculated with Listeria monocytogenes ATCC 19115 and L. monocytogenes ATCC 19112 during seven days of storage at 4°C. The chitosan coating prepared with acetic acid showed the most effective antibacterial activity. All tested formulations of chitosan films exhibited strong antimicrobial activity on the growth of L. monocytogenes on black radish, although a higher inhibition of pathogens was achieved at higher concentrations of chitosan. The antimicrobial effect of chitosan films was even more pronounced with the addition of essential oils. Chitosan-gelatin films with thyme essential oils showed the most effective antimicrobial activity. A reduction of 2.4log10CFU/g for L. monocytogenes ATCC 19115 and 2.1log10CFU/g for L. monocytogenes ATCC 19112 was achieved in the presence of 1% chitosan film containing 0.2% of thyme essential oil after 24h of storage. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Synthesis of a novel amphiphilic quaternized chitosan and its distribution in rats.

PubMed

Liu, Xiaofei; Zeng, Anrong; Li, Lin; Yang, Fan; Wang, Qi; Sun, Zhong; Shen, Jun

2011-01-01

A novel amphiphilic chitosan derivative, N-[(2-hydroxy-3-N,N-dimethylhexadecyl ammonium)propyl]chitosan chloride (N-CQCs), was prepared with a degree of substitution (DS) of 15.58%. N-CQCs was positively charged and its zeta potential was +28.4 mV. The introduction of a long carbon chain with a quaternary ammonium salt group into the chitosan backbone enabled N-CQCs to be lipotropic and hydrophilic. According to the hypothesis of the hypocholesterolemic effect of N-CQCs, its organ distribution in rats was investigated 48 h after administration via gavage using fluorescein isothiocyanate labeling. N-CQCs showed lower cytotoxicity. The plasma half-life of N-CQCs in rats was 48 h and the plasma AUC0-48 h (P) was 371.70 μg/ml per h, suggesting that N-CQCs remained in body for a long time. The results also showed that the accumulation in adipose tissue and gastrointestinal tract was higher than in thymus, kidney, liver and spleen at 48 h after administration. It could be presumed that N-CQCs play an important part in the metabolic process of body fat. Adipose tissue and gastrointestinal tract were the probable interaction sites of N-CQCs and body fat.

Dense chitosan surgical membranes produced by a coincident compression-dehydration process

PubMed Central

Dooley, Thomas P.; Ellis, April L.; Belousova, Maria; Petersen, Don; DeCarlo, Arthur A.

2012-01-01

High density chitosan membranes were produced via a novel manufacturing process for use as implantable resorbable surgical membranes. The innovative method utilizes the following three sequential steps: (1) casting an acidic chitosan solution within a silicon mold, followed by freezing; (2) neutralizing the frozen acidic chitosan solution in alkaline solution to facilitate polymerization; and (3) applying coincident compression-dehydration under a vacuum. Resulting membranes of 0.2 – 0.5 mm thickness have densities as high as 1.6 g/cm3. Inclusion of glycerol prior to the compression-dehydration step provides additional physical and clinical handling benefits. The biomaterials exhibit tensile strength with a maximum load as high as 10.9 N at ~ 2.5 mm width and clinically-relevant resistance to suture pull-out with a maximum load as high as 2.2 N. These physical properties were superior to those of a commercial reconstituted collagen membrane. The dense chitosan membranes have excellent clinical handling characteristics, such as pliability and “memory” when wet. They are semi-permeable to small molecules, biodegradable in vitro in lysozyme solution, and the rates of degradation are inversely correlated to the degree of deacetylation. Furthermore, the dense chitosan membranes are biocompatible and resorbable in vivo as demonstrated in a rat oral wound healing model. The unique combination of physical, in vitro, in vivo, and clinical handling properties demonstrate the high utility of dense chitosan membranes produced by this new method. The materials may be useful as surgical barrier membranes, scaffolds for tissue engineering, wound dressings, and as delivery devices for active ingredients. PMID:23565872

Functionalized and graft copolymers of chitosan and its pharmaceutical applications.

PubMed

Bhavsar, Chintan; Momin, Munira; Gharat, Sankalp; Omri, Abdelwahab

2017-10-01

Chitosan is the second most abundant natural polysaccharide. It belongs a family of polycationic polymers comprised of repetitive units of glucosamine and N-acetylglucosamine. Its biodegradability, nontoxicity, non-immunogenicity and biocompatibility along with properties like mucoadhesion, fungistatic and bacteriogenic have made chitosan an appreciated polymer with numerous applications in the pharmaceutical, comestics and food industry. However, the limited solubility of chitosan at alkaline and neutral pH limits its widespread commercial use. This can be circumvented by fabrication of chitosan by graft copolymerization with acyl, alkyl, monomeric and polymeric moieties. Areas covered: Modifications like quarterization, thiolation, acylation and grafting result in copolymers with higher mucoadhesion strength, increased hydrophobic interactions (advantageous in hydrophobic drug entrapment), and increased solubility in alkaline pH, the ability for adsorption of metal ions, protein and peptide delivery and nutrient delivery. Insights on methods of polymerization, including atomic transfer radical polymerization and click chemistry are discussed. Applications of such modified chitosan copolymers in medical and surgical, and drug delivery, including nasal, oral and buccal delivery have also been covered. Expert opinion: Despite a number of successful investigations, commercialization of chitosan copolymers still remains a challenge. Further advancements in polymerization techniques may address the unmet needs of the healthcare industry.

Synthesis and anticoagulant activity of the quaternary ammonium chitosan sulfates.

PubMed

Fan, Lihong; Wu, Penghui; Zhang, Jinrong; Gao, Song; Wang, Libo; Li, Mingjia; Sha, Mingming; Xie, Weiguo; Nie, Min

2012-01-01

Quaternary ammonium chitosan sulfates with diverse degrees of substitution (DS) ascribed to sulfate groups between 0.52 and 1.55 were synthesized by reacting quaternary ammonium chitosan with an uncommon sulfating agent (N(SO(3)Na)(3)) that was prepared from sodium bisulfite (NaHSO(3)) through reaction with sodium nitrite (NaNO(2)) in the aqueous system homogeneous. The structures of the derivatives were characterized by FTIR, (1)H NMR and (13)C NMR. The factors affecting DS of quaternary ammonium chitosan sulfates which included the molar ratio of NaNO(2) to quaternary ammonium chitosan, sulfated temperature, sulfated time and pH of sulfated reaction solution were investigated in detail. Its anticoagulation activity in vitro was determined by an activated partial thromboplastin time (APTT) assay, a thrombin time (TT) assay and a prothrombin time (PT) assay. Results of anticoagulation assays showed quaternary ammonium chitosan sulfates significantly prolonged APTT and TT, but not PT, and demonstrated that the introduction of sulfate groups into the quaternary ammonium chitosan structure improved its anticoagulant activity obviously. The study showed its anticoagulant properties strongly depended on its DS, concentration and molecular weight. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

International, prospective haemovigilance study on methylene blue-treated plasma.

PubMed

Noens, L; Vilariño, Ma D; Megalou, A; Qureshi, H

2017-05-01

Methylene blue is a phenothiazine dye, which in combination with visible light has virucidal and bactericidal properties, disrupting the replication of a broad range of enveloped viruses and some non-enveloped viruses. The study objective was to collect data on adverse reactions occurring with methylene blue plasma administered in a routine clinical practice environment and document their characteristics and severity. This was an open label, multicentre, non-controlled, non-randomized, non-interventional study. Patients who receive a methylene blue plasma transfusion were observed for any signs and symptoms (adverse reactions) within 24 h safter the start of the transfusion, in different hospitals for a study duration of at least 1 year. A total of 19 315 methylene blue plasma units were transfused. There were eight patients with adverse reactions recorded during the study, one of them serious. Two had more than one reaction (two and four, respectively). Three patients had previous transfusions with methylene blue plasma only. Methylene blue plasma has a very acceptable safety profile with a rate of serious adverse reactions of 0·5/10 000 units. © 2017 International Society of Blood Transfusion.

Fusion of a Novel Genetically Engineered Chitosan Affinity Protein and Green Fluorescent Protein for Specific Detection of Chitosan In Vitro and In Situ

PubMed Central

Nampally, Malathi; Moerschbacher, Bruno Maria

2012-01-01

Chitin is the second most abundant polysaccharide, present, e.g., in insect and arthropod exoskeletons and fungal cell walls. In some species or under specific conditions, chitin appears to be enzymatically de-N-acetylated to chitosan—e.g., when pathogenic fungi invade their host tissues. Here, the deacetylation of chitin is assumed to represent a pathogenicity mechanism protecting the fungus from the host's chitin-driven immune response. While highly specific chitin binding lectins are well known and easily available, this is not the case for chitosan-specific probes. This is partly due to the poor antigenicity of chitosan so that producing high-affinity, specific antibodies is difficult. Also, lectins with specificity to chitosan have been described but are not commercially available, and our attempts to reproduce the findings were not successful. We have, therefore, generated a fusion protein between a chitosanase inactivated by site-directed mutagenesis, the green fluorescent protein (GFP), and StrepII, as well as His6 tags for purification and detection. The recombinant chitosan affinity protein (CAP) expressed in Escherichia coli was shown to specifically bind to chitosan, but not to chitin, and the affinity increased with decreasing degree of acetylation. In vitro, CAP detection was possible either based on GFP fluorescence or using Strep-Tactin conjugates or anti-His5 antibodies. CAP fluorescence microscopy revealed binding to the chitosan exposing endophytic infection structures of the wheat stem rust fungus, but not the chitin exposing ectophytic infection structures, verifying its suitability for in situ chitosan staining. PMID:22367086

P[N(i-Bu)CH(2)CH(2)](3)N: nonionic Lewis base for promoting the room-temperature synthesis of α,β-unsaturated esters, fluorides, ketones, and nitriles using Wadsworth-Emmons phosphonates.

PubMed

Chintareddy, Venkat Reddy; Ellern, Arkady; Verkade, John G

2010-11-05

The bicyclic triaminophosphine P(RNCH(2)CH(2))(3)N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of α,β-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and 1d led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.

Methylene Blue Inhibits Caspases by Oxidation of the Catalytic Cysteine.

PubMed

Pakavathkumar, Prateep; Sharma, Gyanesh; Kaushal, Vikas; Foveau, Bénédicte; LeBlanc, Andrea C

2015-09-24

Methylene blue, currently in phase 3 clinical trials against Alzheimer Disease, disaggregates the Tau protein of neurofibrillary tangles by oxidizing specific cysteine residues. Here, we investigated if methylene blue can inhibit caspases via the oxidation of their active site cysteine. Methylene blue, and derivatives, azure A and azure B competitively inhibited recombinant Caspase-6 (Casp6), and inhibited Casp6 activity in transfected human colon carcinoma cells and in serum-deprived primary human neuron cultures. Methylene blue also inhibited recombinant Casp1 and Casp3. Furthermore, methylene blue inhibited Casp3 activity in an acute mouse model of liver toxicity. Mass spectrometry confirmed methylene blue and azure B oxidation of the catalytic Cys163 cysteine of Casp6. Together, these results show a novel inhibitory mechanism of caspases via sulfenation of the active site cysteine. These results indicate that methylene blue or its derivatives could (1) have an additional effect against Alzheimer Disease by inhibiting brain caspase activity, (2) be used as a drug to prevent caspase activation in other conditions, and (3) predispose chronically treated individuals to cancer via the inhibition of caspases.

Methylene Blue Inhibits Caspases by Oxidation of the Catalytic Cysteine

PubMed Central

Pakavathkumar, Prateep; Sharma, Gyanesh; Kaushal, Vikas; Foveau, Bénédicte; LeBlanc, Andrea C.

2015-01-01

Methylene blue, currently in phase 3 clinical trials against Alzheimer Disease, disaggregates the Tau protein of neurofibrillary tangles by oxidizing specific cysteine residues. Here, we investigated if methylene blue can inhibit caspases via the oxidation of their active site cysteine. Methylene blue, and derivatives, azure A and azure B competitively inhibited recombinant Caspase-6 (Casp6), and inhibited Casp6 activity in transfected human colon carcinoma cells and in serum-deprived primary human neuron cultures. Methylene blue also inhibited recombinant Casp1 and Casp3. Furthermore, methylene blue inhibited Casp3 activity in an acute mouse model of liver toxicity. Mass spectrometry confirmed methylene blue and azure B oxidation of the catalytic Cys163 cysteine of Casp6. Together, these results show a novel inhibitory mechanism of caspases via sulfenation of the active site cysteine. These results indicate that methylene blue or its derivatives could (1) have an additional effect against Alzheimer Disease by inhibiting brain caspase activity, (2) be used as a drug to prevent caspase activation in other conditions, and (3) predispose chronically treated individuals to cancer via the inhibition of caspases. PMID:26400108

Visible light driven photocatalytic degradation of methylene blue using novel camphor sulfonic acid doped polycarbazole/g-C3N4 nanocomposite

NASA Astrophysics Data System (ADS)

Praveena, P.; Dhanavel, S.; Sangamithirai, D.; Narayanan, V.; Stephen, A.

2018-04-01

A novel polycabazole(PCz)/graphitic carbon nitride(g-C3N4) nanocomposite was synthesized via chemical oxidative polymerization method. In the present work, camphor sulfonic acid (CSA) was used as a dopantand ammonium peroxydisulphate (APS) was used as an oxidizing agent. The PCz/g-C3N4 nanocompositewas characterizedusing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-Visible spectroscopy (UV-Vis). The obtained results confirm the successful formation of PCz/g-C3N4 nanocomposite. Visible light induced photocatalytic activity of the novel catalyst was demonstrated using methylene blue as a target pollutant. The results suggestthat PCz/g-C3N4 nanocomposite can be used as an effective catalyst for the degradation of organic pollutants from waste water.

Pseudo-thermosetting chitosan hydrogels for biomedical application.

PubMed

Berger, J; Reist, M; Chenite, A; Felt-Baeyens, O; Mayer, J M; Gurny, R

2005-01-20

To prepare transparent chitosan/beta-glycerophosphate (betaGP) pseudo-thermosetting hydrogels, the deacetylation degree (DD) of chitosan has been modified by reacetylation with acetic anhydride. Two methods (I and II) of reacetylation have been compared and have shown that the use of previously filtered chitosan, dilution of acetic anhydride and reduction of temperature in method II improves efficiency and reproducibility. Chitosans with DD ranging from 35.0 to 83.2% have been prepared according to method II under homogeneous and non-homogeneous reacetylation conditions and the turbidity of chitosan/betaGP hydrogels containing homogeneously or non-homogeneously reacetylated chitosan has been investigated. Turbidity is shown to be modulated by the DD of chitosan and by the homogeneity of the medium during reacetylation, which influences the distribution mode of the chitosan monomers. The preparation of transparent chitosan/betaGP hydrogels requires a homogeneously reacetylated chitosan with a DD between 35 and 50%.

Pseudo-thermosetting chitosan hydrogels for biomedical application.

PubMed

Berger, J; Reist, M; Chenite, A; Felt-Baeyens, O; Mayer, J M; Gurny, R

2005-01-06

To prepare transparent chitosan/beta-glycerophosphate (betaGP) pseudo-thermosetting hydrogels, the deacetylation degree (DD) of chitosan has been modified by reacetylation with acetic anhydride. Two methods (I and II) of reacetylation have been compared and have shown that the use of previously filtered chitosan, dilution of acetic anhydride and reduction of temperature in method II improves efficiency and reproducibility. Chitosans with DD ranging from 35.0 to 83.2% have been prepared according to method II under homogeneous and non-homogeneous reacetylation conditions and the turbidity of chitosan/betaGP hydrogels containing homogeneously or non-homogeneously reacetylated chitosan has been investigated. Turbidity is shown to be modulated by the DD of chitosan and by the homogeneity of the medium during reacetylation, which influences the distribution mode of the chitosan monomers. The preparation of transparent chitosan/betaGP hydrogels requires a homogeneously reacetylated chitosan with a DD between 35 and 50%.

Comparative study of porous hydroxyapatite/chitosan and whitlockite/chitosan scaffolds for bone regeneration in calvarial defects

PubMed Central

Zhou, Ding; Qi, Chao; Chen, Yi-Xuan; Zhu, Ying-Jie; Sun, Tuan-Wei; Chen, Feng; Zhang, Chang-Qing

2017-01-01

Hydroxyapatite (HAP; Ca10(PO4)6(OH)2) and whitlockite (WH; Ca18Mg2(HPO4)2(PO4)12) are widely utilized in bone repair because they are the main components of hard tissues such as bones and teeth. In this paper, we synthesized HAP and WH hollow microspheres by using creatine phosphate disodium salt as an organic phosphorus source in aqueous solution through microwave-assisted hydrothermal method. Then, we prepared HAP/chitosan and WH/chitosan composite membranes to evaluate their biocompatibility in vitro and prepared porous HAP/chitosan and WH/chitosan scaffolds by freeze drying to compare their effects on bone regeneration in calvarial defects in a rat model. The experimental results indicated that the WH/chitosan composite membrane had a better biocompatibility, enhancing proliferation and osteogenic differentiation ability of human mesenchymal stem cells than HAP/chitosan. Moreover, the porous WH/chitosan scaffold can significantly promote bone regeneration in calvarial defects, and thus it is more promising for applications in tissue engineering such as calvarial repair compared to porous HAP/chitosan scaffold. PMID:28435251

Investigation of the effects of local glutathione and chitosan administration on incisional oral mucosal wound healing in rabbits.

PubMed

Kılıç, Ciğdem; Güleç Peker, Emine Gülçeri; Acartürk, Füsun; Kılıçaslan, Seda M Sarı; Çoşkun Cevher, Şule

2013-12-01

The aim of the present study was to investigate the effects of local glutathione (GSH) and chitosan applications on the oxidant events and histological changes that occur, during healing processes in rabbits with incisional intraoral mucosal wounds. For this purpose, discs containing glutathione and chitosan (1:1) were prepared and their physicochemical characteristics were evaluated. New Zealand white rabbits were used in in vivo studies. A standard incision was applied to the oral mucosa of rabbits. The rabbits were divided into four groups, being: an untreated incisional group (n=6), a group treated with discs containing GSH+chitosan (n=6), a group treated with discs containing solely chitosan (n=5) and a group treated with discs containing solely GSH (n=5). The levels of malondialdehyde (MDA), glutathione and nitric oxide (NOx) in the oral wound tissues were measured on the fifth day after the injury. Histological changes in the wound tissues were also investigated. The tissue MDA levels in the group treated with the disc containing GSH+chitosan were found to be lower than those in the other groups. There were no statistically significant differences in terms of tissue GSH and NOx levels between the group treated with the disc comprising GSH+chitosan and the control group that had untreated incision wounds. According to the histological findings, wound healing in the group treated with the disc containing solely chitosan was found to be better than in the other groups. The results of the experiments showed that the local application to the intraoral incision wounds of chitosan+GSH, and chitosan alone, can be effective in the wound healing processes of soft tissues and dental implants. Copyright © 2013 Elsevier B.V. All rights reserved.

Halloysite and chitosan oligosaccharide nanocomposite for wound healing.

PubMed

Sandri, Giuseppina; Aguzzi, Carola; Rossi, Silvia; Bonferoni, Maria Cristina; Bruni, Giovanna; Boselli, Cinzia; Cornaglia, Antonia Icaro; Riva, Federica; Viseras, Cesar; Caramella, Carla; Ferrari, Franca

2017-07-15

Halloysite is a natural nanotubular clay mineral (HNTs, Halloysite Nano Tubes) chemically identical to kaolinite and, due to its good biocompatibility, is an attractive nanomaterial for a vast range of biological applications. Chitosan oligosaccharides are homo- or heterooligomers of N-acetylglucosamine and D-glucosamine, that accelerate wound healing by enhancing the functions of inflammatory and repairing cells. The aim of the work was the development of a nanocomposite based on HNTs and chitosan oligosaccharides, to be used as pour powder to enhance healing in the treatment of chronic wounds. A 1:0.05 wt ratio HTNs/chitosan oligosaccharide nanocomposite was obtained by simply stirring the HTNs powder in a 1% w/w aqueous chitosan oligosaccharide solution and was formed by spontaneous ionic interaction resulting in 98.6% w/w HTNs and 1.4% w/w chitosan oligosaccharide composition. Advanced electron microscopy techniques were considered to confirm the structure of the hybrid nanotubes. Both HTNs and HTNs/chitosan oligosaccharide nanocomposite showed good in vitro biocompatibility with normal human dermal fibroblasts up to 300μg/ml concentration and enhanced in vitro fibroblast motility, promoting both proliferation and migration. The HTNs/chitosan oligosaccharide nanocomposite and the two components separately were tested for healing capacity in a murine (rat) model. HTNs/chitosan oligosaccharide allowed better skin reepithelization and reorganization than HNTs or chitosan oligosaccharide separately. The results suggest to develop the nanocomposite as a medical device for wound healing. The present work is focused on the development of halloysite and chitosan oligosaccharide nanocomposite for wound healing. It considers a therapeutic option for difficult to heal skin lesions and burns. The significance of the research considers two fundamental aspects: the first one is related to the development of a self-assembled nanocomposite, formed by spontaneous ionic

Oxygen and nitrogen plasma etching of three-dimensional hydroxyapatite/chitosan scaffolds fabricated by additive manufacturing

NASA Astrophysics Data System (ADS)

Myung, Sung-Woon; Kim, Byung-Hoon

2016-01-01

Three-dimensional (3D) chitosan and hydroxyapatite (HAp)/chitosan (CH) scaffolds were fabricated by additive manufacturing, then their surfaces were etched with oxygen (O2) and nitrogen (N2) plasma. O2 and N2 plasma etching was performed to increase surface properties such as hydrophilicity, roughness, and surface chemistry on the scaffolds. After etching, hydroxyapatite was exposed on the surface of 3D HAp/CH scaffolds. The surface morphology and chemical properties were characterized by contact angle measurement, scanning electron microscopy, X-ray diffraction, and attenuated total reflection Fourier infrared spectroscopy. The cell viability of 3D chitosan scaffolds was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The differentiation of preosteoblast cells was evaluated by alkaline phosphatase assay. The cell viability was improved by O2 and N2 plasma etching of 3D chitosan scaffolds. The present fabrication process for 3D scaffolds might be applied to a potential tool for preparing biocompatible scaffolds.

Highly efficient hydrophosphonylation of aldehydes and unactivated ketones catalyzed by methylene-linked pyrrolyl rare earth metal amido complexes.

PubMed

Zhou, Shuangliu; Wu, Zhangshuan; Rong, Jiewei; Wang, Shaowu; Yang, Gaosheng; Zhu, Xiancui; Zhang, Lijun

2012-02-27

A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) with 2-(2,6-Me(2)C(6)H(3)NHCH(2))C(4)H(3)NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ-η(5):η(1)):η(1)-2-[(2,6-Me(2)C(6)H(3))NCH(2)](C(4)H(3)N)LnN(SiMe(3))(2)}(2) [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by (1)H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol%) afforded the products in high yields (up to 99%) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99% with employment of low loadings (0.1 to 0.5 mol%) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel transmucosal absorption enhancers obtained by aminoalkylation of chitosan.

PubMed

Zambito, Ylenia; Uccello-Barretta, Gloria; Zaino, Chiara; Balzano, Federica; Di Colo, Giacomo

2006-12-01

Literature data suggest that quaternized chitosans have a transmucosal drug absorption enhancing property depending on their MW, quaternization degree and other structural features. With the purpose of preparing novel effective promoters, a chitosan (Ch) from crab shell (ChC; viscometric MW, 800 kDa; deacetylation: 90%, IR; 84%, NMR) and one from shrimp shell (ChS; viscometric MW, 590 kDa; deacetylation: 90%, IR; 82%, NMR) were reacted with 2-diethylaminoethyl chloride (DEAE-Cl) and novel derivatives containing different percentages of pendant quaternary ammonium groups were obtained. NMR analysis, based on HSQC, COSY, TOCSY and ROESY maps, indicated that three partially substituted N,O-[N,N-diethylaminomethyl(diethyldimethylene ammonium)(n)]methyl chitosans, coded N(+)-ChS-2 (degree of substitution, DS=40%; n=1.6), N(+)-ChS-4 (DS=132%; n=2.5), and N(+)-ChC-4 (DS=85%; n=1.7) resulted from the reaction, depending on whether the DEAE-Cl/Ch repeating unit molar ratio, was 2:1 or 4:1. The effects of the derivatives on the permeability of rhodamine 123 (Rh-123), hydrophobic, marker of the transcellular absorption route, and of fluorescein sodium (NaFlu), polar, marker of the paracellular route, across excised porcine cheek epithelium were assessed, using Franz type diffusion cells. Rh-123 permeability was enhanced by N(+)-ChS-4 (enhancement ratio, ER=8.4) and by N(+)-ChC-4 (ER=3.9), whereas N(+)-ChS-2 was ineffective. NaFlu permeability was enhanced by N(+)-ChS-2 (ER=7.2), N(+)-ChS-4 (ER=7.4) and N(+)-ChC-4 (ER=6.6). In conclusion, the three derivatives, whichever their DS, promote paracellular transport, while transcellular transport is substantially accelerated only by the most substituted one.

Effects of Paclitaxel-conjugated N-Succinyl-Hydroxyethyl Chitosan Film for Proliferative Cholangitis in Rabbit Biliary Stricture Model.

PubMed

Wang, Tao; Zou, Hao; Liu, Yun-Xia; Zhang, Xiao-Wen

2018-03-20

Paclitaxel (PTX) could inhibit the growth of fibroblasts, which occurs in proliferative cholangitis and leads to biliary stricture. However, its use has been limited due to poor bioavailability and local administration for short time. This study designed and synthesized a new PTX-conjugated chitosan film (N-succinyl-hydroxyethyl chitosan containing PTX [PTX-SHEC]) and evaluated its safety and efficiency using in vivo and in vitro experiments. The SHEC conjugated with PTX was confirmed by nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FT-IR) measurements. Drug releases in vitro and in vivo were determined using high-performance liquid chromatography. Cell viability in vitro was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. Rabbit biliary stricture model was constructed. All rabbits randomly divided into five groups (n = 8 in each group): the sham-operated rabbits were used as control (Group A), Groups B received laparotomies and suture, Group C received laparotomies and covered SHEC suture without the PTX coating, Group D received laparotomies and covered PTX-SHEC suture, and Group E received laparotomies and 1000 μmol/L PTX administration. Liver function tests and residual dosage of PTX from each group were measured by enzyme-linked immunosorbent assay. Histological data and α-smooth muscle actin (SMA) immunohistochemical staining of common bile duct were examined. NMR and FT-IR indicated that PTX was successfully introduced, based on the appearance of signals at 7.41-7.99 ppm, 1.50 ppm, and 1.03 ppm, due to the presence of aromatic protons, methylene protons, and methyl protons of PTX, respectively. No bile leak was observed. The PTX-conjugated film could slowly release PTX for 4 weeks (8.89 ± 0.03 μg at day 30). The in vitro cell viability test revealed significantly different levels of toxicity between films with and without PTX (111.7 ± 4.0% vs. 68.1 ± 6.0%, P < 0.001), whereas no statistically

The effect of chitosan and whey proteins-chitosan films on the growth of Penicillium expansum in apples.

PubMed

Simonaitiene, Dovile; Brink, Ieva; Sipailiene, Ausra; Leskauskaite, Daiva

2015-05-01

Penicillium expansum causes a major post-harvest disease of apples. The aim of this study was to investigate the inhibition effect of chitosan and whey proteins-chitosan films containing different amounts of quince and cranberry juice against P. expansum on the simulation medium and on apples. The mechanical properties of films were also evaluated. The presence of cranberry and quince juice in the composition of chitosan and whey proteins-chitosan films caused a significant (P ≤ 0.05) increase in elasticity and decrease in tensile strength of films. Chitosan and whey proteins-chitosan films with quince and cranberry juice demonstrated a significant (P ≤ 0.05) inhibition effect against P. expansum growth on the simulated medium and apples. The presence of cranberry juice in the composition of chitosan and whey proteins-chitosan films resulted in a longer lag phase and a lower P. expansum growth rate on the simulation medium in comparison with films made with the addition of quince juice. These differences were not evident when experiment was conducted with apples. Addition of quince and cranberry juice to the chitosan and whey proteins-chitosan films as natural antifungal agents has some potential for prolonging the shelf life of apples. © 2014 Society of Chemical Industry.

21 CFR 520.154a - Bacitracin methylene disalicylate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... prevention of necrotic enteritis caused by Clostridium perfringens susceptible to bacitracin methylene.... perfringens susceptible to bacitracin methylene disalicylate. (B) Limitations. Prepare a fresh solution daily...) Indications for use. For prevention of ulcerative enteritis due to Clostridium colinum susceptible to...

Differential responses of nitrifying archaea and bacteria to methylene blue toxicity.

PubMed

Sipos, A J; Urakawa, H

2016-02-01

Methylene blue, a heterocyclic aromatic chemical compound used to treat fish diseases in the ornamental fish aquaculture industry, is believed to impair nitrification as a side effect. However, very little is known about the toxicity of methylene blue to nitrifying micro-organisms. Here, we report the susceptibility of six bacterial and one archaeal ammonia-oxidizing micro-organisms to methylene blue within the range of 10 ppb to 10 ppm. Remarkably high susceptibility was observed in the archaeal species Nitrosopumilus maritimus compared to the bacterial species. Ammonia oxidation by Nitrosopumilus maritimus was inhibited 65% by 10 ppb of methylene blue. Of the bacterial species examined, Nitrosococcus oceani was the most resistant to methylene blue toxicity. For similar inhibition of Nitrosococcus oceani (75% inhibition), one thousand times more methylene blue (10 ppm) was needed. The examination of single cell viability on Nitrosomonas marina demonstrated that methylene blue is lethal to the cells rather than reducing their single cell ammonia oxidation activity. The level of susceptibility to methylene blue was related to the cell volume, intracytoplasmic membrane arrangement and the evolutionary lineage of nitrifying micro-organisms. Our findings are relevant for effectively using methylene blue in various aquaculture settings by helping minimize its impact on nitrifiers during the treatment of fish diseases. In the future, resistant nitrifiers such as Nitrosococcus oceani may be purposely added to aquaculture systems to maintain nitrification activity during treatments with methylene blue. The susceptibility of six bacterial and one archaeal nitrifying micro-organisms to methylene blue was tested. Remarkably high susceptibility was observed in the archaeal species compared to the bacterial species. The level of resistance to methylene blue was related to the cell volume, cytomembrane system and the taxonomic position of the nitrifying micro

Chitin and Chitosan: Production and Application of Versatile Biomedical Nanomaterials

PubMed Central

Elieh-Ali-Komi, Daniel; Hamblin, Michael R

2016-01-01

Chitin is the most abundant aminopolysaccharide polymer occurring in nature, and is the building material that gives strength to the exoskeletons of crustaceans, insects, and the cell walls of fungi. Through enzymatic or chemical deacetylation, chitin can be converted to its most well-known derivative, chitosan. The main natural sources of chitin are shrimp and crab shells, which are an abundant byproduct of the food-processing industry, that provides large quantities of this biopolymer to be used in biomedical applications. In living chitin-synthesizing organisms, the synthesis and degradation of chitin require strict enzymatic control to maintain homeostasis. Chitin synthase, the pivotal enzyme in the chitin synthesis pathway, uses UDP-N-acetylglucosamine (UDPGlcNAc), produce the chitin polymer, whereas, chitinase enzymes degrade chitin. Bacteria are considered as the major mediators of chitin degradation in nature. Chitin and chitosan, owing to their unique biochemical properties such as biocompatibility, biodegradability, non-toxicity, ability to form films, etc, have found many promising biomedical applications. Nanotechnology has also increasingly applied chitin and chitosan-based materials in its most recent achievements. Chitin and chitosan have been widely employed to fabricate polymer scaffolds. Moreover, the use of chitosan to produce designed-nanocarriers and to enable microencapsulation techniques is under increasing investigation for the delivery of drugs, biologics and vaccines. Each application is likely to require uniquely designed chitosan-based nano/micro-particles with specific dimensions and cargo-release characteristics. The ability to reproducibly manufacture chitosan nano/microparticles that can encapsulate protein cargos with high loading efficiencies remains a challenge. Chitosan can be successfully used in solution, as hydrogels and/or nano/microparticles, and (with different degrees of deacetylation) an endless array of derivatives with

Rat urinary metabolites of [9,10-methylene-14C] sterculic acid.

PubMed

Eisele, T A; Yoss, J K; Nixon, J E; PAwlowski, N E; Libbey, L M; Sinnhuber, R O

1977-07-20

1. The metabolism of [9,10-methylene-14C] sterculic acid was studied in corn oil and Stercula foetida oil fed rats. The majority of the radioactivity was excreted into the urine as short chain dicarboxylic acids. The main urinary metabolites were cis-3,4-methylene adipic acid, cis-3,4-methylene suberic acid, trans-3,4-methylene adipic acid, cis-3,4-methylene pimelic acid, and cis-3,4-methylene azelic acid. 2. Formation of these urinary metabolites requires alpha-, beta-, and omega-oxidation plus reduction of the cyclopropene ring to a cyclopropane ring. Sterculic acid must be transported through both mitochondrial and microsomal systems. 3. Other non-radioactive urinary compounds were also identified. A proposed pathway for the metabolism of sterculic acid and possible detrimental effects caused by these metabolites is discussed.

Application of chitosan and its N-heterocyclic derivatives for preconcentration of noble metal ions and their determination using atomic absorption spectrometry.

PubMed

Azarova, Yu A; Pestov, A V; Ustinov, A Yu; Bratskaya, S Yu

2015-12-10

Chitosan and its N-heterocyclic derivatives N-2-(2-pyridyl)ethylchitosan (2-PEC), N-2-(4-pyridyl) ethylchitosan (4-PEC), and N-(5-methyl-4-imidazolyl) methylchitosan (IMC) have been applied in group preconcentration of gold, platinum, and palladium for subsequent determination by atomic absorption spectroscopy (AAS) in solutions with high background concentrations of iron and sodium ions. It has been shown that the sorption mechanism, which was elucidated by XPS, significantly influences the sorption capacity of materials, the efficiency of metal ions elution after preconcentration, and, as a result, the accuracy of metal determination by AAS. We have shown that native chitosan was not suitable for preconcentration of Au(III), if the elution step was used as a part of the analysis scheme. The group preconcentration of Au(III), Pd(II), and Pt(IV) with subsequent quantitative elution using 0.1M HCl/1M thiourea solution was possible only on IMC and 4-PEC. Application of IMC for analysis of the national standard quartz ore sample proved that gold could be accurately determined after preconcentration/elution with the recovery above 80%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pharmacological performance of novel poly-(ionic liquid)-grafted chitosan-N-salicylidene Schiff bases and their complexes.

PubMed

Elshaarawy, Reda F M; Refaee, Ayaat A; El-Sawi, Emtithal A

2016-08-01

In our endeavor to develop a new class of pharmacological candidates with antimicrobial and anticancer efficacy, a series of biopolymeric chitosan Schiff bases bearing salicylidene ionic liquid (IL-Sal) brushes (ILCSB1-3, poly-(GlcNHAc-GlcNH2-(GlcN-Sal-IL)) was successfully synthesized by adopting efficient synthetic routes. Unfortunately, metalation trials of these biopolymeric Schiff bases afford the corresponding Ag(I)/M(II) complexes (where M=Co, Pd). These designed architectures were structurally characterized and pharmacologically evaluated for their in vitro antimicrobial, against common bacterial and fungal pathogens, and anticancer activities against human colon carcinoma (HCT-116) cell line. In conclusion functionalization of chitosan with IL-Sal brushes coupled with metalation of formed ILCSBs were synergistically enhanced its antimicrobial and antitumor properties to a great extent. Noteworthy, Ag-ILCSB2 (IC50=9.13μg/mL) was ca. 5-fold more cytotoxic against HCT-116 cell line than ILCSB2 (IC50=43.30μg/mL). Copyright © 2016. Published by Elsevier Ltd.

Cholic acid modified N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride for superoxide dismutase delivery.

PubMed

Cheng, Ye; Cai, Huanxin; Yin, Baoru; Yao, Ping

2013-09-15

A series of novel amphiphilic chitosan derivatives, cholic acid modified N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (HTCC-CA) with different quaternization degrees and cholic acid substitutions were synthesized in this study. HTCC-CA is biocompatible and forms particles in aqueous solution. The binding with superoxide dismutase (SOD) at pH 6.8 destroys the original aggregates of HTCC-CA and produces smaller SOD/HTCC-CA complex nanoparticles via electrostatic and hydrophobic interactions. The SOD loading efficiency and loading capacity of HTCC-CA can reach to more than 90% and 45%, respectively. Confocal laser scanning microscopy observation and flow cytometry analysis reveal that SOD/HTCC-CA complex nanoparticles greatly enhance the cellular internalization of the loaded SOD. The SOD activities and malonaldehyde concentrations in the serum and organs of the rats, administrated intravenously with free SOD, free HTCC-CA, and SOD/HTCC-CA nanoparticles, were assayed to evaluate the antioxidant efficiency in vivo. The results demonstrate that free HTCC-CA is effective to scavenge superoxide radicals in the blood circulation and SOD/HTCC-CA nanoparticles have better antioxidant efficiency than free SOD as well as free HTCC-CA. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and evaluation of N-naphthyl-N,O-succinyl chitosan micelles containing clotrimazole for oral candidiasis treatment.

PubMed

Tonglairoum, Prasopchai; Woraphatphadung, Thisirak; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Akkaramongkolporn, Prasert; Sajomsang, Warayuth; Opanasopit, Praneet

2017-03-01

Clotrimazole (CZ)-loaded N-naphthyl-N,O-succinyl chitosan (NSCS) micelles have been developed as an alternative for oral candidiasis treatment. NSCS was synthesized by reductive N-amination and N,O-succinylation. CZ was incorporated into the micelles using various methods, including the dropping method, the dialysis method, and the O/W emulsion method. The size and morphology of the CZ-loaded micelles were characterized using dynamic light scattering measurements (DLS) and a transmission electron microscope (TEM), respectively. The drug entrapment efficiency, loading capacity, release characteristics, and antifungal activity against Candida albicans were also evaluated. The CZ-loaded micelles prepared using different methods differed in the size of micelles. The micelles ranged in size from 120 nm to 173 nm. The micelles prepared via the O/W emulsion method offered the highest percentage entrapment efficiency and loading capacity. The CZ released from the CZ-loaded micelles at much faster rate compared to CZ powder. The CZ-loaded NSCS micelles can significantly hinder the growth of Candida cells after contact. These CZ-loaded NSCS micelles offer great antifungal activity and might be further developed to be a promising candidate for oral candidiasis treatment.

Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan

PubMed Central

Kumirska, Jolanta; Czerwicka, Małgorzata; Kaczyński, Zbigniew; Bychowska, Anna; Brzozowski, Krzysztof; Thöming, Jorg; Stepnowski, Piotr

2010-01-01

Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds. PMID:20559489

Herstellung von Chitosan und einige Anwendungen

NASA Astrophysics Data System (ADS)

Struszczyk, Marcin Henryk

2001-05-01

. Die aus Chitosan-Dispersionen hergestellten MCChB-Filme weisen bessere mechanische Eigenschaften (Bruchfestigkeit, Dehnung) und eine höhere Wasseraufnahmefähigkeit auf als Filme, die nach herkömmlichen Methoden aus sauerer Lösung hergestellt werden. Die Einführung von Proteinen ändert die mechanischen Eigenschaften der MCChB-Filme abhängig von der Art, der Proteine sowie des DD und der Mv des eingesetzte Chitosan. Die Zugabe von Protein beschleunigt den biologischen Abbau der MCChB-Filme. Aus den untersuchten MCChB-Filmen mit Proteinzusatz können leichte, reißfeste und dennoch elastische Materialen hergestellt werden. 4. Mit Hilfe von MCChB-Dispersion kann Papier modifiziert werden. Dadurch werden die mechanischen Eigenschaften verbessert und die Wasseraufnahme wird verringert. Die Zugabe von Proteinen verringert das Wasseraufnahmevermögen noch weiter. Ein geringes Wasseraufnahmevermögen ist der bedeutendste Faktor bei der Papierherstellung. Auch Papier, das mit einem MCChB-Protein-Komplexe modifiziert wurde, zeigt gute mechanische Eigenschaften. 5. Wird Chitosan durch unmittelbare Einführung von MCChB auf Cellulose-Fasern aufgebracht, so erhält man eine netzartige Struktur, während durch Ausfällung aufgebrachtes Chitosan eine dünne Schicht auf den Cellulose-Fasern bildet. Die netzartige Struktur erleichtert die Bioabbaubarkeit, während die Schichtstruktur diese erschwert. 6. Die guten mechanischen Eigenschaften, die geringe Wasseraufnahmefähigkeit und die mit Cellulose vergleichbare Bioabbaubarkeit von Papier, das mit MCChB modifiziert wurde, lassen MCChB für die Veredlung von Papier nützlich erscheinen. 1. Deacetylation of the crustacean chitosan causes drastically decrease in the Mv with increasing reaction temperature and time as well as the concentration of sodium hydroxide. However, the DD are relatively less affected. Pandalus borealis is a good source for production of chitosan having high Mv and low DD, whereas chitosan of medium to low Mv

Chitin and chitosan from the Norway lobster by-products: Antimicrobial and anti-proliferative activities.

PubMed

Sayari, Nadhem; Sila, Assaâd; Abdelmalek, Baha Eddine; Abdallah, Rihab Ben; Ellouz-Chaabouni, Semia; Bougatef, Ali; Balti, Rafik

2016-06-01

Chitin was recovered through enzymatic deproteinization of the Norway lobster (Nephrops norvegicus) processing by-products. The obtained chitin was characterized and converted into chitosan by N-deacetylation, the acid-soluble form of chitin. Chitosan samples were then characterized by Fourier transform infrared spectroscopy (FTIR) and 13 Cross polarization magic angle spinning nuclear magnetic resonance (CP/MAS)-NMR spectroscopy. The antimicrobial activity and anti-proliferative capacity of chitosan were evaluated. Antimicrobial activity assays indicated that prepared chitosan exhibited marked inhibitory activity against the bacterial and fungal strains tested. Further, cytotoxic effects of chitosan samples on human colon carcinoma cells HCT116 was evaluated using the MTT assay. Chitosan showed the antiproliferative capacity against the colon-cancer-cell HCT116 in a dose dependent manner with IC50 of 4.6mg/ml. Indeed, HCT116 cell proliferation was significantly inhibited (p<0.05) between 13.5 and 67.5% at 0.5-6mg/mL of chitosan after 24h of cell treatment. The chitosan showed high antitumor activity which seemed to be dependent on its characteristics such as acetylation degree. Copyright © 2016 Elsevier B.V. All rights reserved.

Pharmacokinetics and biodegradation of chitosan in rats

NASA Astrophysics Data System (ADS)

Li, Hui; Jiang, Zhiwen; Han, Baoqin; Niu, Shuyi; Dong, Wen; Liu, Wanshun

2015-10-01

Chitosan, an excellent biomedical material, has received a widespread in vivo application. In contrast, its metabolism and distribution once being implanted were less documented. In this study, the pharmacokinetics and biodegradation of fluorescein isothiocyanate (FITC) labeled and muscle implantation administrated chitosan in rats were investigated with fluorescence spectrophotometry, histological assay and gel chromatography. After implantation, chitosan was degraded gradually during its distribution to diverse organs. Among the tested organs, liver and kidney were found to be the first two highest in chitosan content, which was followed by heart, brain and spleen. Urinary excretion was believed to be the major pathway of chitosan elimination, yet 80% of chitosan administered to rats was not trackable in their urine. This indicated that the majority of chitosan was degraded in tissues. In average, the molecular weight of the degradation products of chitosan in diverse organs and urine was found to be <65 kDa. This further confirmed the in vivo degradation of chitosan. Our findings provided new evidences for the intensive and safe application of chitosan as a biomedical material.

High-efficiency volume holograms recording on acrylamide and N,N'methylene-bis-acrylamide photopolymer with pulsed laser

NASA Astrophysics Data System (ADS)

Gallego, Sergi; Ortuno, Manuel; Garcia, Celia; Neipp, Cristian; Belendez, Augusto; Pascual, Inmaculada V.

2004-09-01

In order to achieve higher diffraction efficiencies of the volume gratings stored in acrylamide based photopolymer, we introduce in the photopolymer a crosslinker (N,N'methylene-bis-acrylamide). The presence of this component increase the rate polymerization and the modulation of refraction index. The recording was performed using a holographic copying process. The original was a grating of 1000 lines/mm processed using silver halide sensitized gelatine, with diffraction efficiency around 50 % for a reconstruction wavelength of 532 nm. The main beam was split in two secondary beams by the original grating, with an intensity ratio 1:1. The results obtained using the new composition of material are compared with the composition without crosslinker. In the other hand the no linearity of the material's response is also studied comparing the energetic sensitivity, diffraction efficiencies and index modulation of gratings recorded with pulsed and continuous laser. This study is realized fitting the angular scan of each grating using Kogelnik's theory. The gratings are recorded with wavelength of 532 nm when pulsed exposure is used and with wavelength of 514 nm when continues exposure is used. Using pulsed laser at 532 nm the photopolymer without crosslinker presents the diffraction efficiencies lightly smaller than 60%. In the other hand when the crosslinker has been introduced in photopolymer composition, the diffraction efficiencies achieves are higher than 85 %.

Inhibition of dog and human gastric lipases by enantiomeric phosphonate inhibitors: a structure-activity study.

PubMed

Miled, Nabil; Roussel, Alain; Bussetta, Cécile; Berti-Dupuis, Liliane; Rivière, Mireille; Buono, Gérard; Verger, Robert; Cambillau, Christian; Canaan, Stéphane

2003-10-14

The crystal structures of gastric lipases in the apo form [Roussel, A., et al. (1999) J. Biol. Chem. 274, 16995-17002] or in complex with the (R(P))-undecyl butyl phosphonate [C(11)Y(4)(+)] [Roussel, A., et al. (2002) J. Biol. Chem. 277, 2266-2274] have improved our understanding of the structure-activity relationships of acid lipases. In this report, we have performed a kinetic study with dog and human gastric lipases (DGL and HGL, respectively) using several phosphonate inhibitors by varying the absolute configuration of the phosphorus atom and the chain length of the alkyl/alkoxy substituents. Using the two previously determined structures and that of a new crystal structure obtained with the other (S(P))-phosphonate enantiomer [C(11)Y(4)(-)], we constructed models of phosphonate inhibitors fitting into the active site crevices of DGL and HGL. All inhibitors with a chain length of fewer than 12 carbon atoms were found to be completely buried in the catalytic crevice, whereas longer alkyl/alkoxy chains were found to point out of the cavity. The main stereospecific determinant explaining the stronger inhibition of the S(P) enantiomers is the presence of a hydrogen bond involving the catalytic histidine as found in the DGL-C(11)Y(4)(-) complex. On the basis of these results, we have built a model of the first tetrahedral intermediate corresponding to the tristearoyl-lipase complex. The triglyceride molecule completely fills the active site crevice of DGL, in contrast with what is observed with other lipases such as pancreatic lipases which have a shallower and narrower active site. For substrate hydrolysis, the supply of water molecules to the active site might be achieved through a lateral channel identified in the protein core.

Role of N-acetyltransferase 2 acetylation polymorphism in 4, 4'-methylene bis (2-chloroaniline) biotransformation.

PubMed

Hein, David W; Zhang, Xiaoyan; Doll, Mark A

2018-02-01

Arylamine N-acetyltransferase 1 (NAT1) and 2 (NAT2) catalyze the acetylation of arylamine carcinogens. Single nucleotide polymorphisms in the NAT2 coding exon present in NAT2 haplotypes encode allozymes with reduced N-acetyltransferase activity towards the N-acetylation of arylamine carcinogens and the O-acetylation of their N-hydroxylated metabolites. NAT2 acetylator phenotype modifies urinary bladder cancer risk following exposures to arylamine carcinogens such as 4-aminobiphenyl. 4, 4'-methylene bis (2-chloroaniline) (MOCA) is a Group 1 carcinogen for which a role of the NAT2 acetylation polymorphism on cancer risk is unknown. We investigated the role of NAT2 and the genetic acetylation polymorphism on both MOCA N-acetylation and N-hydroxy-MOCA O-acetylation. MOCA N-acetylation exhibited a robust gene dose response in rabbit liver cytosol and in cryopreserved human hepatocytes derived from individuals of rapid, intermediate and slow acetylator NAT2 genotype. MOCA exhibited about 4-fold higher affinity for recombinant human NAT2 than NAT1. Recombinant human NAT2*4 (reference) and 15 variant recombinant human NAT2 allozymes catalyzed both the N-acetylation of MOCA and the O-acetylation of N-hydroxy-MOCA. Human NAT2 5, NAT2 6, NAT2 7 and NAT2 14 allozymes catalyzed MOCA N-acetylation and N-hydroxy-O-acetylation at rates much lower than the reference NAT2 4 allozyme. In conclusion, our results show that NAT2 acetylator genotype has an important role in MOCA metabolism and suggest that risk assessments related to MOCA exposures consider accounting for NAT2 acetylator phenotype in the analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison and Characterisation of Regenerated Chitosan from 1-Butyl-3-methylimidazolium Chloride and Chitosan from Crab Shells

PubMed Central

Arnold, Lyndon

2015-01-01

Chitosan is a biopolymer derived from chitin which is naturally occurring in the exoskeleton of crustaceans. This paper reports dissolution and regeneration of chitosan by directly dissolving in an ionic liquid solvent, 1-butyl-3-methylimidazolium chloride (BMIMCl). This will provide an ideal platform to solubilise these kinds of polymers to achieve the dissolution. The current study dissolved chitosan from crab shell utilising BMIMCl as a solvent and characterised the resultant regenerated polymer. The regenerated chitosan showed increased hydrogen bonding when characterised by Fourier transform infrared (FTIR) spectral analysis. In addition, the study also compared the characteristics of regenerated and generic chitosan. The regenerated chitosan was also evaluated for antimicrobial properties and showed to possess antibacterial features similar to the commercial grade. This method can be utilised in future for blending of polymers with chitosan in a dissolved phase. PMID:26090452

Evaluation of phosphonate treatments for control of phytophthora crown rot of walnut

USDA-ARS?s Scientific Manuscript database

Foliar and soil applications of phosphonate were evaluated in a factorial manner for control of trunk cankers caused by Phytophthora citricola in a Persian walnut orchard, cultivar ‘Chandler’. In each of two experiments, the foliar treatment was applied once in the second week of September, whereas...

Phosphorus sorption on marine carbonate sediment: phosphonate as model organic compounds.

PubMed

Huang, Xiao-Lan; Zhang, Jia-Zhong

2011-11-01

Organophosphonate, characterized by the presence of a stable, covalent, carbon to phosphorus (C-P) bond, is a group of synthetic or biogenic organophosphorus compounds. The fate of these organic phosphorus compounds in the environment is not well studied. This study presents the first investigation on the sorption of phosphorus (P) in the presence of two model phosphonate compounds, 2-aminothylphosphonoic acid (2-AEP) and phosphonoformic acid (PFA), on marine carbonate sediments. In contrast to other organic P compounds, no significant inorganic phosphate exchange was observed in seawater. P was found to adsorb on the sediment only in the presence of PFA, not 2-AEP. This indicated that sorption of P from phosphonate on marine sediment was compound specific. Compared with inorganic phosphate sorption on the same sediments, P sorption from organic phosphorus is much less in the marine environment. Further study is needed to understand the potential role of the organophosphonate compounds in biogeochemical cycle of phosphorus in the environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

A simple and convenient method to synthesize N-[(2-hydroxyl)-propyl-3-trimethylammonium] chitosan chloride in an ionic liquid.

PubMed

Yang, Xiaodeng; Zhang, Chuanguang; Qiao, Congde; Mu, Xueli; Li, Tianduo; Xu, Jinku; Shi, Lei; Zhang, Dongju

2015-10-05

N-[(2-Hydroxyl)-propyl-3-trimethyl ammonium] chitosan chloride (HTCC) was synthesized through nucleophilic substitution of 2,3-epoxypropyltrimethyl ammonium chloride (EPTAC) onto chitosan using ionic liquid of 1-allyl-3-methylimidazole chloride (AmimCl) as a homogeneous and green reaction media. The chemical structure of HTCC was confirmed by FTIR, (1)H NMR and (13)C NMR. The FTIR peak intensity of amino group at 1595 cm(-1) decreased and that of [Formula: see text] at 1475 cm(-1) increased with the increase of reaction time, confirming the substitution of EPTAC on CS. The degree of substitutions (DS) were calculated from the integral area of (1)H NMR, and the optimum reaction condition was obtained, namely, reaction time of 8h, temperature of 80°C and [Formula: see text] of 3/1. The degree of crystallinity and thermal properties of HTCC were characterized by XRD, TG, DSC, and DMA methods. Data from XRD, TG, DSC and DMA show that the degree of crystallinity, thermal stability, as well as glass transition temperature of HTCC decreased with the increase of DS. The reaction mechanism of chitosan with EPTAC in AmimCl was elucidated by performing density functional theory (DFT) calculations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry.

PubMed

Bauer, Anna; Luetjohann, Jens; Rohn, Sascha; Kuballa, Juergen; Jantzen, Eckard

2018-01-10

A new sensitive, fast, and robust method using ion chromatography tandem mass spectrometry (IC-MS/MS) for the determination of fosetyl and phosphonic acid in plant-derived matrices was developed. For compensation of matrix effects and differences in recovery rates the isotopically labeled internal standard (ILIS) 18 O 3 -labeled phosphonic acid was added to the samples prior to the extraction of the target compounds. The validation of the method for the matrices tomato, apple, lemon, sultana, avocado, and wheat was performed according to the actual EU guidance document SANTE/11945/2015. The precision and accuracy were determined in five replicates at spiking levels of 0.010 and 0.100 mg/kg with recovery rates between 76 and 105% and RSDs between 1.2 and 17.8%. In this paper, it was achieved for the first time to detect both fosetyl and phosphonic acid at the reporting level of 0.010 mg/kg most relevant for organic plant food commodities.

Synthesis and kinetic evaluation of cyclophostin and cyclipostins phosphonate analogs as selective and potent inhibitors of microbial lipases.

PubMed

Point, Vanessa; Malla, Raj K; Diomande, Sadia; Martin, Benjamin P; Delorme, Vincent; Carriere, Frederic; Canaan, Stephane; Rath, Nigam P; Spilling, Christopher D; Cavalier, Jean-François

2012-11-26

A new series of customizable diastereomeric cis- and trans-monocyclic enol-phosphonate analogs to Cyclophostin and Cyclipostins were synthesized. Their potencies and mechanisms of inhibition toward six representative lipolytic enzymes belonging to distinct lipase families were examined. With mammalian gastric and pancreatic lipases no inhibition occurred with any of the compounds tested. Conversely, Fusarium solani Cutinase and lipases from Mycobacterium tuberculosis (Rv0183 and LipY) were all fully inactivated. The best inhibitors displayed a cis conformation (H and OMe) and exhibited higher inhibitory activities than the lipase inhibitor Orlistat toward the same enzymes. Our results have revealed that chemical group at the γ-carbon of the phosphonate ring strongly impacts the inhibitory efficiency, leading to a significant improvement in selectivity toward a target lipase over another. The powerful and selective inhibition of microbial (fungal and mycobacterial) lipases suggests that these seven-membered monocyclic enol-phosphonates should provide useful leads for the development of novel and highly selective antimicrobial agents.

Synthesis and kinetic evaluation of Cyclophostin and Cyclipostins phosphonate analogs as selective and potent inhibitors of microbial lipases

PubMed Central

Point, Vanessa; Malla, Raj K.; Diomande, Sadia; Martin, Benjamin P.; Delorme, Vincent; Carriere, Frederic; Canaan, Stephane; Rath, Nigam P.; Spilling, Christopher D.; Cavalier, Jean-François

2012-01-01

New series of customizable diastereomeric cis- and trans-monocyclic enol-phosphonate analogs to Cyclophostin and Cyclipostins were synthesized. Their potencies and mechanisms of inhibition toward six representative lipolytic enzymes belonging to distinct lipase families were examined. With mammalian gastric and pancreatic lipases no inhibition occurred with any of the compounds tested. Conversely, Fusarium solani Cutinase and lipases from Mycobacterium tuberculosis (Rv0183 and LipY) were all fully inactivated. Best inhibitors displayed a cis conformation (H and OMe) and exhibited higher inhibitory activities than the lipase inhibitor Orlistat towards same enzymes. Our results have revealed that chemical group at the γ-carbon of the phosphonate ring strongly impacts the inhibitory efficiency, leading to a significant improvement in selectivity toward a target lipase over another. The powerful and selective inhibition of microbial (fungal and mycobacterial) lipases suggests that these 7-membered monocyclic enol-phosphonates should provide useful leads for the development of novel and highly selective antimicrobial agents. PMID:23095026

Neurometabolic mechanisms for memory enhancement and neuroprotection of methylene blue

PubMed Central

Rojas, Julio C.; Bruchey, Aleksandra K.; Gonzalez-Lima, F.

2011-01-01

This paper provides the first review of the memory-enhancing and neuroprotective metabolic mechanisms of action of methylene blue in vivo. These mechanisms have important implications as a new neurobiological approach to improve normal memory and to treat memory impairment and neurodegeneration associated with mitochondrial dysfunction. Methylene blue’s action is unique because its neurobiological effects are not determined by regular drug-receptor interactions or drug-response paradigms. Methylene blue shows a hormetic dose-response, with opposite effects at low and high doses. At low doses, methylene blue is an electron cycler in the mitochondrial electron transport chain, with unparalleled antioxidant and cell respiration-enhancing properties that affect the function of the nervous system in a versatile manner. A major role of the respiratory enzyme cytochrome oxidase on the memory-enhancing effects of methylene blue is supported by available data. The memory-enhancing effects have been associated with improvement of memory consolidation in a network-specific and use-dependent fashion. In addition, low doses of methylene blue have also been used for neuroprotection against mitochondrial dysfunction in humans and experimental models of disease. The unique auto-oxidizing property of methylene blue and its pleiotropic effects on a number of tissue oxidases explain its potent neuroprotective effects at low doses. The evidence reviewed supports a mechanistic role of low-dose methylene blue as a promising and safe intervention for improving memory and for the treatment of acute and chronic conditions characterized by increased oxidative stress, neurodegeneration and memory impairment. PMID:22067440

The use of functionalized monoalkyl phosphates and phosphonates in the colloidal processing of oxide ceramic powders

NASA Astrophysics Data System (ADS)

Radsick, Timothy Carl

The purpose of this study was to develop phosphorous-based chemicals that could be used to modify the interparticle pair potential of several oxide ceramic particles, thereby enabling their use in colloidal processing schemes. Several procedures for the synthesis of 11-12 carbon alpha,o-functionalized monoalkyl phosphates and phosphonates were developed. Because of its simplicity and its use of mild reagents, a procedure based on the Michaelis-Arbuzov rearrangement was selected to produce the bulk of the chemicals used in this study. Carboxyl- and hydroxyl-terminated monoalkyl phosphonates were adsorbed onto alumina and zirconia powders using either aqueous-based or solvent-based methods to produce a monolayer of "brushlike" steric molecules. In the aqueous-based methods, powders were processed at pH values below their isoelectric point in order to produce a positive charge on the powder, thereby attracting the negatively charged phosphate or phosphonate group onto the powder surface to form the steric monolayer. In solvent-based methods, powder was suspended in an acetone solution of the phosphonates, heated at reflux, washed, dried and heat treated at 120°C under vacuum. The zeta potential of the coated powders was measured to quantify the degree of steric layer adsorption and the shift in the isoelectric point. Slurries of coated alumina and zirconia were prepared having 20 vol % powder. Rheological behavior was studied by measuring viscosity as a function of shear rate for slurries of various pH values and counterion concentrations. Slurries with powder processed via the solvent method were the least sensitive to changes in slurry pH and were straightforward to prepare. It is thought that the solvent-based coating procedure produced a stronger, multi-dentate powder-phosphonate bond than that of the aqueous-based procedure. Dispersed and coagulated slurries were able to be prepared over a wide pH range, including at the isoelectric point of the uncoated powders

Effects of chitosan combined with nisin treatment on storage quality of large yellow croaker (Pseudosciaena crocea).

PubMed

Hui, Guohua; Liu, Wei; Feng, Hailin; Li, Jian; Gao, Yuanyuan

2016-07-15

Effects of chitosan combined with different concentrations of nisin on quality enhancement of large yellow croaker (Pseudosciaena crocea) stored at 4 °C were evaluated for 8 days. Changes in sensory score and volatile spoilage products, total viable counts (TVC), and physiochemical indexes including weight loss, colour, pH, total volatile basic nitrogen (TVB-N), and K-value were examined. Results demonstrated that nisin-treated samples presented better quality preservation effects than chitosan alone. 1% chitosan combined with 0.6% nisin presented optimal quality enhancement effects, such as moisture loss control, volatile spoilage inhibition, TVB-N reduction, TVC growth control, and colour and sensory acceptability maintenance. Therefore, chitosan combined with nisin is promising in large yellow croaker shelf life extension. Copyright © 2016 Elsevier Ltd. All rights reserved.

Environmental applications of chitosan and its derivatives.

PubMed

Yong, Soon Kong; Shrivastava, Manoj; Srivastava, Prashant; Kunhikrishnan, Anitha; Bolan, Nanthi

2015-01-01

Chitosan originates from the seafood processing industry and is one of the most abundant of bio-waste materials. Chitosan is a by-product of the alkaline deacetylation process of chitin. Chemically, chitosan is a polysaccharide that is soluble in acidic solution and precipitates at higher pHs. It has great potential for certain environmental applications, such as remediation of organic and inorganic contaminants, including toxic metals and dyes in soil, sediment and water, and development of contaminant sensors. Traditionally, seafood waste has been the primary source of chitin. More recently, alternative sources have emerged such as fungal mycelium, mushroom and krill wastes, and these new sources of chitin and chitosan may overcome seasonal supply limitations that have existed. The production of chitosan from the above-mentioned waste streams not only reduces waste volume, but alleviates pressure on landfills to which the waste would otherwise go. Chitosan production involves four major steps, viz., deproteination, demineralization, bleaching and deacetylation. These four processes require excessive usage of strong alkali at different stages, and drives chitosan's production cost up, potentially making the application of high-grade chitosan for commercial remediation untenable. Alternate chitosan processing techniques, such as microbial or enzymatic processes, may become more cost-effective due to lower energy consumption and waste generation. Chitosan has proved to be versatile for so many environmental applications, because it possesses certain key functional groups, including - OH and -NH2 . However, the efficacy of chitosan is diminished at low pH because of its increased solubility and instability. These deficiencies can be overcome by modifying chitosan's structure via crosslinking. Such modification not only enhances the structural stability of chitosan under low pH conditions, but also improves its physicochemical characteristics, such as porosity

Improvement of absorption enhancing effects of n-dodecyl-beta-D-maltopyranoside by its colon-specific delivery using chitosan capsules.

PubMed

Fetih, Gihan; Lindberg, Sara; Itoh, Katsuhito; Okada, Naoki; Fujita, Takuya; Habib, Fawsia; Artersson, Per; Attia, Mohammed; Yamamoto, Akira

2005-04-11

In general, absorption enhancing effects of various absorption enhancers were greater in the large intestine than those in the small intestinal regions. Therefore, the effectiveness of absorption enhancers is expected to be remarkably observed, if these enhancers can be delivered to the large intestine with some poorly absorbable drugs after oral administration. In this study, therefore, we examined whether chitosan capsules were effective for the colon-specific delivery of a certain absorption enhancer and can improve the absorption enhancing action of the absorption enhancer after oral administration. 5(6)-Carboxyfluorescein (CF) was used as a model drug to investigate the site-dependent effectiveness of various absorption enhancers by an in situ closed loop method. Sodium glycocholate (NaGC), n-dodecyl-beta-d-maltopyranoside (LM), sodium salicylate (NaSal) and sodium caprate (NaCap) were used as models of absorption enhancers in this study. Overall, the absorption enhancing effects of these enhancers for intestinal absorption of CF were greater in the colon than those in the jejunum and the ileum. Especially, among these enhancers tested in this study, LM showed much greater absorption enhancing effect in the colon than in the jejunum and the ileum. Therefore, LM was selected as a model absorption enhancer to examine the effect of chitosan capsules on the absorption enhancing effect of LM. When CF and LM were orally administered to rats using chitosan capsules, the plasma concentration of CF was much higher than those in other dosage forms including solution and gelatin capsules. Therefore, chitosan capsules may be useful carriers for colon-specific delivery of LM, thereby increasing its absorption enhancing effect from the intestinal membranes.

Microgel-Encapsulated Methylene Blue for the Treatment of Breast Cancer Cells by Photodynamic Therapy

PubMed Central

Khanal, Anil; Bui, Minh-Phuong Ngoc

2014-01-01

Purpose Photodynamic therapy (PDT) is gaining increasing recognition for breast cancer treatment because it offers local selectivity and reduced toxic side effects compared to radiotherapy and chemotherapy. In PDT, photosensitizer drugs are loaded in different nanomaterials and used in combination with light exposure. However, the most representative issue with PDT is the difficulty of nanomaterials to encapsulate anticancer drugs at high doses, which results in low efficacy of the PDT treatment. Here, we proposed the development of the poly(N-isopropylacrylamide) (PNIPAM) microgel for the encapsulation of methylene blue, an anticancer drug, for its use as breast cancer treatment in MCF-7 cell line. Methods We developed biocompatible microgels based on nonfunctionalized PNIPAM and its corresponding anionically functionalized PNIPAM and polyacrylic acid (PNIPAM-co-PAA) microgel. Methylene blue was used as the photosensitizer drug because of its ability to generate toxic reactive oxygen species upon exposure to light at 664 nm. Core PNIPAM and core/shell PNIPAM-co-PAA microgels were synthesized and characterized using ultraviolet-visible spectroscopy and dynamic light scattering. The effect of methylene blue was evaluated using the MCF-7 cell line. Results Loading of methylene blue in core PNIPAM microgel was higher than that in the core/shell PNIPAM-co-PAA microgel, indicating that electrostatic interactions did not play an important role in loading a cationic drug. This behavior is probably due to the skin layer inhibiting the high uptake of drugs in the PNIPAM-co-PAA microgel. Core PNIPAM microgel effectively retained the cationic drug (i.e., methylene blue) for several hours compared to core/shell PNIPAM-co-PAA and enhanced its photodynamic efficacy in vitro more than that of free methylene blue. Conclusion Our results showed that the employment of core PNIPAM and core/shell PNIPAM-co-PAA microgels enhanced the encapsulation of methylene blue. Core PNIPAM

Microgel-encapsulated methylene blue for the treatment of breast cancer cells by photodynamic therapy.

PubMed

Khanal, Anil; Bui, Minh-Phuong Ngoc; Seo, Seong S

2014-03-01

Photodynamic therapy (PDT) is gaining increasing recognition for breast cancer treatment because it offers local selectivity and reduced toxic side effects compared to radiotherapy and chemotherapy. In PDT, photosensitizer drugs are loaded in different nanomaterials and used in combination with light exposure. However, the most representative issue with PDT is the difficulty of nanomaterials to encapsulate anticancer drugs at high doses, which results in low efficacy of the PDT treatment. Here, we proposed the development of the poly(N-isopropylacrylamide) (PNIPAM) microgel for the encapsulation of methylene blue, an anticancer drug, for its use as breast cancer treatment in MCF-7 cell line. We developed biocompatible microgels based on nonfunctionalized PNIPAM and its corresponding anionically functionalized PNIPAM and polyacrylic acid (PNIPAM-co-PAA) microgel. Methylene blue was used as the photosensitizer drug because of its ability to generate toxic reactive oxygen species upon exposure to light at 664 nm. Core PNIPAM and core/shell PNIPAM-co-PAA microgels were synthesized and characterized using ultraviolet-visible spectroscopy and dynamic light scattering. The effect of methylene blue was evaluated using the MCF-7 cell line. Loading of methylene blue in core PNIPAM microgel was higher than that in the core/shell PNIPAM-co-PAA microgel, indicating that electrostatic interactions did not play an important role in loading a cationic drug. This behavior is probably due to the skin layer inhibiting the high uptake of drugs in the PNIPAM-co-PAA microgel. Core PNIPAM microgel effectively retained the cationic drug (i.e., methylene blue) for several hours compared to core/shell PNIPAM-co-PAA and enhanced its photodynamic efficacy in vitro more than that of free methylene blue. Our results showed that the employment of core PNIPAM and core/shell PNIPAM-co-PAA microgels enhanced the encapsulation of methylene blue. Core PNIPAM microgel released the drug more slowly

Synthesis and characterization of Ag2S decorated chitosan nanocomposites and chitosan nanofibers for removal of lincosamides antibiotic.

PubMed

Gupta, Vinod Kumar; Fakhri, Ali; Agarwal, Shilpi; Azad, Mona

2017-10-01

We report the synthesis of Ag 2 S-Chitosan nanocomposites and Ag 2 S-chitosan nanohybrids as performance adsorbents for Lincosamides such as Clindamycin antibiotic removal. Isotherms and kinetic studies were determined to understand the adsorption behavior both two adsorbent. At low adsorbent dose, removals are increased in the adsorption process, and performance is better with Ag 2 S-chitosan nanohybrids due to the special surface area increased. The average sizes and surface area of Ag 2 S-Chitosan nanocomposites and Ag 2 S-chitosan nanohybrids were found as 50nm, 70nm and 180.18, 238.24m 2 g -1 , respectively. In particular, Ag 2 S-Chitosan nanocomposites and Ag 2 S-chitosan nanohybrids show high maximum Clindamycin adsorption capacity (q max ) of 153.21, and 181.28mgg -1 , respectively. More strikingly, Ag 2 S-Chitosan nanocomposites and Ag 2 S-chitosan nanohybrids are also demonstrated to nearly completely remove Clindamycin from drinking water. The excellent adsorption performance along with their cost effective, convenient synthesis makes this range of adsorbents highly promising for commercial applications in drinking water and wastewater treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

[The clinical value of sentinel lymph node detection in laryngeal and hypopharyngeal carcinoma patients with clinically negative neck by methylene blue method and radiolabeled tracer method].

PubMed

Zhao, Xin; Xiao, Dajiang; Ni, Jianming; Zhu, Guochen; Yuan, Yuan; Xu, Ting; Zhang, Yongsheng

2014-11-01

To investigate the clinical value of sentinel lymph node (SLN) detection in laryngeal and hypopharyngeal carcinoma patients with clinically negative neck (cN0) by methylene blue method, radiolabeled tracer method and combination of these two methods. Thirty-three patients with cN0 laryngeal carcinoma and six patients with cN0 hypopharyngeal carcinoma underwent SLN detection using both of methylene blue and radiolabeled tracer method. All these patients were accepted received the injection of radioactive isotope 99 Tc(m)-sulfur colloid (SC) and methylene blue into the carcinoma before surgery, then all these patients underwent intraopertive lymphatic mapping with a handheld gamma-detecting probe and blue-dyed SLN. After the mapping of SLN, selected neck dissections and tumor resections were peformed. The results of SLN detection by radiolabeled tracer, dye and combination of both methods were compared. The detection rate of SLN by radiolabeled tracer, methylene blue and combined method were 89.7%, 79.5%, 92.3% respectively. The number of detected SLN was significantly different between radiolabeled tracer method and combined method, and also between methylene blue method and combined method. The detection rate of methylene blue and radiolabeled tracer method were significantly different from combined method (P < 0.05). Nine patients were found to have lymph node metastasis by final pathological examination. The accuracy and negative rate of SLN detection of the combined method were 97.2% and 11.1%. The combined method using radiolabeled tracer and methylene blue can improve the detection rate and accuracy of sentinel lymph node detection. Furthermore, sentinel lymph node detection can accurately represent the cervical lymph node status in cN0 laryngeal and hypopharyngeal carcinoma.

[Experimental study on the chitosan-DNA vaccines against campylobacter jejuni invasion].

PubMed

Zheng, Hui; Cai, Fang-cheng; Zhong, Min; Deng, Bing; Li, Xin; Zhang, Xiao-ping

2007-09-01

The immunogenicity and protective efficacy of an experimental Campylobacter jejuni (C. jejuni) chitosan-DNA vaccines were evaluated in mice. The chitosan-DNA vaccines were prepared by embedding pcDNA3.1(+)-cadF and pcDNA3.1(+)-peblA with chitosan respectively. BALB/c mice were intranasally immunized in a four-dose primary series (7 d intervals) at doses of 60 microg chitosan-DNA vaccines each time. The comparative immunogenicities of nine formulations were assessed on the basis of the generation of antigen-specific antibodies in serum and intestinal secretions. Mice were attacked repeatedly through intragastric administration of C. jejuni HS:19 at the 8th week after the immunization and protective efficacy was determined by detecting the degrees of protection afforded against C. jejuni invaded. The mice immunized with chitosan-DNA vaccines have generated high levels of IgA and IgG from the sera and IgA from the intestinal secretions and the P/N value went up to 20.58, 30.13 and 6.87 respectively. Meanwhile, the expression of intestinal SIgA increased correspondingly. Moreover the chitosan-DNA vaccines induced strongest level of protection in BALB/c mice against challenge with C. jejuni HS:19 strain and the protective efficacies was 93.70. The results of this study indicate that the chitosan-DNA vaccines could induce significant protective immunity against C. jejuni challenge in the mice model.

The preparation and antioxidant activity of the sulfanilamide derivatives of chitosan and chitosan sulfates.

PubMed

Zhong, Zhimei; Ji, Xia; Xing, Ronge; Liu, Song; Guo, Zhanyong; Chen, Xiaolin; Li, Pengcheng

2007-06-01

Chitosan (CS) and chitosan sulfates (CSS) with different molecular weight (Mw) were reacted with 4-acetamidobenzene sulfonyl chloride to obtain sulfanilamide derivatives of chitosan and chitosan sulfates (LSACS, HSACS, LSACSS, HSACSS). The preparation conditions such as different reaction time, temperature, solvent, and the molar ratio of reaction materials are discussed in this paper. Their structures were characterized by FTIR spectroscopy and elemental analyses. The antioxidant activities of the derivatives were investigated employing various established in vitro systems, such as hydroxyl-radical ((*)OH) superoxide anion (O2(*-)) scavenging and reducing power. All kinds of the compounds (HCS, LCS, HCSS, LCSS, HSACS, LSACS, HSACSS, LSACSS) showed stronger scavenging activity on hydroxyl radical than ascorbic acid (Vc). The inhibitory activities of the derivatives toward superoxide radical by the PMS-NADH system were obvious. The experiment showed that the superoxide radical scavenging effect of sulfanilamide derivatives of chitosan and chitosan sulfates was stronger than that of original CS and CSS. All of the derivatives were efficient in the reducing power. The results indicated that the sulfanilamide group were grafted on CS and CSS increased the reducing power of them obviously.

Metal phosphonate coordination networks and frameworks as precursors of electrocatalysts for the hydrogen and oxygen evolution reactions

NASA Astrophysics Data System (ADS)

Zhang, Rui; El-Refaei, Sayed M.; Russo, Patrícia A.; Pinna, Nicola

2018-05-01

The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) play key roles in the conversion of energy derived from renewable energy sources into chemical energy. Efficient, robust, and inexpensive electrocatalysts are necessary for driving these reactions at high rates at low overpotentials and minimize energetic losses. Recently, electrocatalysts derived from hybrid metal phosphonate compounds have shown high activity for the HER or OER. We review here the utilization of metal phosphonate coordination networks and metal-organic frameworks as precursors/templates for transition-metal phosphides, phosphates, or oxyhydroxides generated in situ in alkaline solutions, and their electrocatalytic performance in HER or OER.

Rhodium-catalyzed enantioselective cyclizations of γ-alkynylaldehydes with acyl phosphonates: ligand- and substituent-controlled C-P or C-H bond cleavage.

PubMed

Masuda, Kengo; Sakiyama, Norifumi; Tanaka, Rie; Noguchi, Keiichi; Tanaka, Ken

2011-05-11

It has been established that a cationic rhodium(I)/(R)-H(8)-BINAP or (R)-Segphos complex catalyzes two modes of enantioselective cyclizations of γ-alkynylaldehydes with acyl phosphonates via C-P or C-H bond cleavage. The ligands of the Rh(I) complexes and the substitutents of both γ-alkynylaldehydes and acyl phosphonates control these two different pathways. © 2011 American Chemical Society

A methylene blue-assisted technique for harvesting lymph nodes after radical surgery for gastric cancer: a prospective, randomized, controlled study.

PubMed

Aoyama, Toru; Fujikawa, Hirohito; Cho, Haruhiko; Ogata, Takashi; Shirai, Junya; Hayashi, Tsutomu; Rino, Yasushi; Masuda, Munetaka; Oba, Mari S; Morita, Satoshi; Yoshikawa, Takaki

2015-02-01

Harvesting lymph nodes (LNs) after gastrectomy is essential for accurate staging. This trial evaluated the efficiency and quality of a conventional method and a methylene blue-assisted method in a randomized manner. The key eligibility criteria were as follows: (i) histologically proven adenocarcinoma of the stomach; (ii) clinical stage I-III; (iii) R0 resection planned by gastrectomy with D1+ or D2 lymphadenectomy. The primary endpoint was the ratio of the pathologic number of harvested LNs per time (minutes) as an efficacy measure. The secondary endpoint was the number of harvested LNs, as a quality measure. Between August 2012 and December 2012, 60 patients were assigned to undergo treatment using the conventional method (n=29) and the methylene blue dye method (n=31). The baseline demographics were mostly well balanced between the 2 groups. The number of harvested LNs (mean±SD) was 33.6±11.9 in the conventional arm and 43.4±13.9 in the methylene blue arm (P=0.005). The ratio of the number of the harvested LNs per time was 1.12±0.46 LNs/min in the conventional arm and 1.49±0.59 LNs/min in the methylene blue arm (P=0.010). In the subgroup analyses, the quality and efficacy were both superior for the methylene blue dye method compared with the conventional method. The methylene blue technique is recommended for harvesting LNs during gastric cancer surgery on the basis of both the quality and efficacy.

Modified methylene blue injection improves lymph node harvest in rectal cancer.

PubMed

Liu, Jianpei; Huang, Pinjie; Zheng, Zongheng; Chen, Tufeng; Wei, Hongbo

2017-04-01

The presence of nodal metastases in rectal cancer plays an important role in accurate staging and prognosis, which depends on adequate lymph node harvest. The aim of this prospective study is to investigate the feasibility and survival benefit of improving lymph node harvest by a modified method with methylene blue injection in rectal cancer specimens. One hundred and thirty-one patients with rectal cancer were randomly assigned to the control group in which lymph nodes were harvested by palpation and sight, or to the methylene blue group using a modified method of injection into the superior rectal artery with methylene blue. Analysis of clinicopathologic records, including a long-term follow-up, was performed. In the methylene blue group, 678 lymph nodes were harvested by simple palpation and sight. Methylene blue injection added 853 lymph nodes to the total harvest as well as 32 additional metastatic lymph nodes, causing a shift to node-positive stage in four patients. The average number of lymph nodes harvested was 11.7 ± 3.4 in the control group and 23.2 ± 4.7 in the methylene blue group, respectively. The harvest of small lymph nodes (<5 mm) and the average number of metastatic nodes were both significantly higher in the methylene blue group. The modified method of injection with methylene blue had no impact on overall survival. The modified method with methylene blue injection improved lymph node harvest in rectal cancer, especially small node and metastatic node retrieval, which provided more accurate staging. However, it was not associated with overall survival. © 2014 Royal Australasian College of Surgeons.

Plasticized chitosan/polyolefin films produced by extrusion.

PubMed

Matet, Marie; Heuzey, Marie-Claude; Ajji, Abdellah; Sarazin, Pierre

2015-03-06

Plasticized chitosan and polyethylene blends were produced through a single-pass extrusion process. Using a twin-screw extruder, chitosan plasticization was achieved in the presence of an acetic acid solution and glycerol, and directly mixed with metallocene polyethylene, mPE, to produce a masterbatch. Different dilutions of the masterbatch (2, 5 and 10 wt% of plasticized chitosan), in the presence of ethylene vinyl acetate, EVA, were subsequently achieved in single screw film extrusion. Very small plasticized chitosan domains (number average diameter <5 μm) were visible in the polymeric matrix. The resulting films presented a brown color and increasing haze with chitosan plasticized content. Mechanical properties of the mPE films were affected by the presence of plasticized chitosan, but improvement was observed as a result of some compatibility between mPE and chitosan in the presence of EVA. Finally the incorporation of plasticized chitosan affected mPE water vapor permeability while oxygen permeability remained constant. Copyright © 2014 Elsevier Ltd. All rights reserved.

A mediator-free glucose biosensor based on glucose oxidase/chitosan/α-zirconium phosphate ternary biocomposite.

PubMed

Liu, Li-Min; Wen, Jiwu; Liu, Lijun; He, Deyong; Kuang, Ren-yun; Shi, Taqing

2014-01-15

A novel glucose oxidase/chitosan/α-zirconium phosphate (GOD/chitosan/α-ZrP) ternary biocomposite was prepared by co-intercalating glucose oxidase (GOD) and chitosan into the interlayers of α-zirconium phosphate (α-ZrP) via a delamination-reassembly procedure. The results of X-ray diffraction, infrared spectroscopy, circular dichroism, and ultraviolet spectrum characterizations indicated not only the layered and hybrid structure of the GOD/chitosan/α-ZrP ternary biocomposite but also the recovered activity of the intercalated GOD improved by the co-intercalated chitosan. By depositing the GOD/chitosan/α-ZrP biocomposite film onto a glassy carbon electrode, the direct electrochemistry of the intercalated GOD was achieved with a fast electron transfer rate constant, k(s), of 7.48±3.52 s(-1). Moreover, this GOD/chitosan/α-ZrP biocomposite modified electrode exhibited a sensitive response to glucose in the linear range of 0.25-8.0 mM (R=0.9994, n=14), with a determination limit of 0.076 mM. Copyright © 2013 Elsevier Inc. All rights reserved.

UV-crosslinkable and thermo-responsive chitosan hybrid hydrogel for NIR-triggered localized on-demand drug delivery.

PubMed

Wang, Lei; Li, Baoqiang; Xu, Feng; Xu, Zheheng; Wei, Daqing; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu

2017-10-15

Innovative drug delivery technologies based on smart hydrogels for localized on-demand drug delivery had aroused great interest. To acquire smart UV-crosslinkable chitosan hydrogel for NIR-triggered localized on-demanded drug release, a novel UV-crosslinkable and thermo-responsive chitosan was first designed and synthesized by grafting with poly N-isopropylacrylamide, acetylation of methacryloyl groups and embedding with photothermal carbon. The UV-crosslinkable unit (methacryloyl groups) endowed chitosan with gelation via UV irradiation. The thermo-responsive unit (poly N-isopropylacrylamide) endowed chitosan hydrogel with temperature-triggered volume shrinkage and reversible swelling/de-swelling behavior. The chitosan hybrid hydrogel embedded with photothermal carbon exhibited distinct NIR-triggered volume shrinkage (∼42% shrinkage) in response to temperature elevation as induced by NIR laser irradiation. As a demonstration, doxorubicin release rate was accelerated and approximately 40 times higher than that from non-irradiated hydrogels. The UV-crosslinkable and thermal-responsive hybrid hydrogel served as in situ forming hydrogel-based drug depot is developed for NIR-triggered localized on-demand release. Copyright © 2017 Elsevier Ltd. All rights reserved.

Colorimetric detection of biothiols based on aggregation of chitosan-stabilized silver nanoparticles

NASA Astrophysics Data System (ADS)

Mohammadi, Somayeh; Khayatian, Gholamreza

2017-10-01

We have described a simple and reliable colorimetric method for the sensing of biothiols such as cysteine, homocysteine, and glutathione in biological samples. The selective binding of chitosan capped silver nanoparticles to biothiols induced aggregation of the chitosan-Ag NPs. But the other amino acids that do not have thiol group cannot aggregate the chitosan-Ag NPs. Aggregation of chitosan-Ag NPs has been confirmed with UV-vis absorption spectra, zeta potential and transmission electron microscopy images. Under optimum conditions, good linear relationships existed between the absorption ratios (at A500/A415) and the concentrations of cysteine, homocysteine, and glutathione in the range of 0.1-10.0 μM with detection limits of 15.0, 84.6 and 40.0 nM, respectively. This probe was successfully applied to detect these biothiols in biological samples (urine and plasma).

Photochemical quenching of aqueous methylene blue by N, Nb co-doped TiO2 nanomaterials under visible light: a confirmatory UV/LC-MS study

NASA Astrophysics Data System (ADS)

Gupta, Kamini; Pandey, Ashutosh; Singh, R. P.

2017-12-01

Nanodimensional un-doped, Nb doped, N doped and N,Nb co-doped TiO2 particles have been prepared by the sol-gel procedure. Phase identification of the anatase particles was done by X-ray powder diffraction and Deby-Scherrer calculations revealed their particle sizes to range from 20 to 30 nm. The band gap energies of the samples were measured by UV-Vis-diffuse reflectance (UV-DRS) spectra. While un-doped TiO2 showed wide optical absorption in the UV region. The co-doped TiO2 particles exhibited narrow band gaps of ~2.7 eV, which showed absorption in the visible region. A decline in charge carrier recombination rates in the prepared samples was confirmed through photoluminescence (PL). The morphological appearances of the particles have been examined by scanning electron microscopy. X-ray photoelectron spectroscopy (XPS) of the samples confirmed the incorporations of N and Nb into the TiO2 matrices. The photocatalytic efficiencies of the prepared particles have been determined by the degradation of the non-biodegradable dye methylene blue (MB) under electromagnetic radiation. The co-doped sample showed superior photocatalytic activity under the visible light (λ  >  400) over the other samples. Photochemical quenching of aqueous MB was further analysed by UV/LC-MS which confirmed the attenuation of methylene blue.

Rapid fixation of methylene chloride by a macrocyclic amine.

PubMed

Lee, Jung-Jae; Stanger, Keith J; Noll, Bruce C; Gonzalez, Carlos; Marquez, Manuel; Smith, Bradley D

2005-03-30

A simple macrocyclic amine is alkylated by methylene chloride to give a quaternary ammonium chloride salt. When methylene chloride is the solvent, the reaction exhibits pseudo-first-order kinetics, and the reaction half-life at 25.0 degrees C is 2.0 min. The reaction half-life for a structurally related, acyclic amine is approximately 50 000 times longer. Detailed calculations favor a mechanism where the methylene chloride associates with the macrocycle to form an activated prereaction complex. The macrocyclic nitrogen subsequently attacks the methylene chloride with a classic SN2 trajectory, and although the carbon-chlorine bond breaks, the chloride leaving group does not separate from the newly formed cationic macrocycle, such that the product is a tightly associated ion-pair. X-ray crystal structures of the starting amine and the product salt, as well as kinetic data, support this mechanism.

Continuous and massive intake of chitosan affects mineral and fat-soluble vitamin status in rats fed on a high-fat diet.

PubMed

Deuchi, K; Kanauchi, O; Shizukuishi, M; Kobayashi, E

1995-07-01

We investigated the effects of continuous and massive intake of chitosan with sodium ascorbate (AsN) on the mineral and the fat-soluble vitamin status in male Sprague-Dawley rats fed on a high-fat diet. The apparent fat digestibility in the chitosan-receiving group was significantly lower than that in the cellulose- or glucosamine-receiving group. Chitosan feeding for 2 weeks caused a decrease in mineral absorption and bone mineral content, and it was necessary to administer twice the amount of Ca in the AIN-76 formula, which was supplemented with AsN, to prevent such a decrease in the bone mineral content. Moreover, the ingestion of chitosan along with AsN led to a marked and rapid decrease in the serum vitamin E level, while such a loss in vitamin E was not observed for rats given glucosamine monomer instead of chitosan.

N-acetylcysteine, Ascorbic Acid, and Methylene Blue for the Treatment of Aluminium Phosphide Poisoning: Still Beneficial?

PubMed Central

Gheshlaghi, Farzad; Lavasanijou, Mohamad Reza; Moghaddam, Noushin Afshar; Khazaei, Majid; Behjati, Mohaddeseh; Farajzadegan, Ziba; Sabzghabaee, Ali Mohammad

2015-01-01

Objectives: Intentional and accidental intoxication with aluminium phosphide (ALP) remains a clinical problem, especially in the Middle East region. Considering the high mortality rate besides lack of any recommended first option drug for its treatment, this study was aimed to compare the therapeutic effects of N-acetylcysteine (NAC), vitamin C (Vit C), and methylene blue; both in isolate and also in combination, for the treatment of ALP intoxication in a rat model. Materials and Methods: In this experimental animal study, 80 male Wistar rats in eight groups were intoxicated with ALP (12.5 mg/kg) and treated with a single dose of NAC (100 mg/kg) or Vit C (500–1,000 mg/kg) or methylene blue (1 mg/kg/5 min, 0.1%) or two of these agents or all three of them (controls were not treated). Rats were monitored regarding the parameters of drug efficacy as increased survival time and reduced morbidity and mortality rate for 3 consecutive days to ensure toxin neutralization. Macroscopic changes were recorded and biopsy sections were taken from brain, cerebellum, kidney, liver, and heart for microscopic evaluation regarding cellular hypoxia. Results: The mean survival times of rats exposed to ALP and treated with VitC + NAC was 210.55±236.22 minutes. In analysis of survival times, there was a significant difference between Group 5 which received VitC + NAC and the other groups (P < 0.01). Serum magnesium levels after death were higher than normal (P = 0.01). Conclusions: Despite the higher survival rate of antioxidant-treated rats compared with controls, this difference was not statistically significant. PMID:26862259

Chitosan Improves Anti-Biofilm Efficacy of Gentamicin through Facilitating Antibiotic Penetration

PubMed Central

Mu, Haibo; Guo, Fan; Niu, Hong; Liu, Qianjin; Wang, Shunchun; Duan, Jinyou

2014-01-01

Antibiotic overuse is one of the major drivers in the generation of antibiotic resistant “super bugs” that can potentially cause serious effects on health. In this study, we reported that the polycationic polysaccharide, chitosan could improve the efficacy of a given antibiotic (gentamicin) to combat bacterial biofilms, the universal lifestyle of microbes in the world. Short- or long-term treatment with the mixture of chitosan and gentamicin resulted in the dispersal of Listeria monocytogenes (L. monocytogenes) biofilms. In this combination, chitosan with a moderate molecular mass (~13 kDa) and high N-deacetylation degree (~88% DD) elicited an optimal anti-biofilm and bactericidal activity. Mechanistic insights indicated that chitosan facilitated the entry of gentamicin into the architecture of L. monocytogenes biofilms. Finally, we showed that this combination was also effective in the eradication of biofilms built by two other Listeria species, Listeria welshimeri and Listeria innocua. Thus, our findings pointed out that chitosan supplementation might overcome the resistance of Listeria biofilms to gentamicin, which might be helpful in prevention of gentamicin overuse in case of combating Listeria biofilms when this specific antibiotic was recommended. PMID:25479075

Disinfection of water with new chitosan-modified hybrid clay composite adsorbent.

PubMed

Unuabonah, Emmanuel I; Adewuyi, Adewale; Kolawole, Matthew O; Omorogie, Martins O; Olatunde, Olalekan C; Fayemi, Scott O; Günter, Christina; Okoli, Chukwunonso P; Agunbiade, Foluso O; Taubert, Andreas

2017-08-01

Hybrid clay composites were prepared from Kaolinite clay and Carica papaya seeds via modification with chitosan, Alum, NaOH, and ZnCl 2 in different ratios, using solvothermal and surface modification techniques. Several composite adsorbents were prepared, and the most efficient of them for the removal of gram negative enteric bacteria was the hybrid clay composite that was surface-modified with chitosan, Ch-nHYCA 1:5 (Chitosan: nHYCA = 1:5). This composite adsorbent had a maximum adsorption removal value of 4.07 × 10 6 cfu/mL for V. cholerae after 120 min, 1.95 × 10 6 cfu/mL for E. coli after ∼180 min and 3.25 × 10 6 cfu/mL for S. typhi after 270 min. The Brouers-Sotolongo model was found to better predict the maximum adsorption capacity ( q max ) of Ch-nHYCA 1:5 composite adsorbent for the removal of E. coli with a q max of 103.07 mg/g (7.93 × 10 7 cfu/mL) and V. cholerae with a q max of 154.18 mg/g (1.19 × 10 8 cfu/mL) while the Sips model best described S. typhi adsorption by Ch-nHYCA 1:5 composite with an estimated q max of 83.65 mg/g (6.43 × 10 7 cfu/mL). These efficiencies do far exceed the alert/action levels of ca. 500 cfu/mL in drinking water for these bacteria. The simplicity of the composite preparation process and the availability of raw materials used for its preparation underscore the potential of this low-cost chitosan-modified composite adsorbent (Ch-nHYCA 1:5 ) for water treatment.

Vibrational spectroscopic and quantum chemical calculations of (E)-N-Carbamimidoyl-4-((naphthalen-1-yl-methylene)amino)benzene sulfonamide.

PubMed

Chandran, Asha; Varghese, Hema Tresa; Mary, Y Sheena; Panicker, C Yohannan; Manojkumar, T K; Van Alsenoy, Christian; Rajendran, G

2012-02-15

FT-IR and FT-Raman spectra of (E)-N-Carbamimidoyl-4-((naphthalen-1-yl-methylene)amino)benzene sulfonamide were recorded and analyzed. The vibrational wavenumbers were computing at various levels of theory. The data obtained from theoretical calculations are used to assign vibrational bands obtained experimentally. The results indicate that B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and structural parameters. The calculated first hyperpolarizability is comparable with reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The geometrical parameters of the title compound are in agreement with that of similar derivatives. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of Cy5.5-Labeled Hydrophobically Modified Glycol Chitosan Nanoparticles for Protein Delivery

NASA Astrophysics Data System (ADS)

Chin, Amanda

Therapeutic proteins are often highly susceptible to enzymatic degradation, thus restricting their in vivo stability. To overcome this limitation, delivery systems designed to promote uptake and reduce degradation kinetics have undergone a rapid shift from macro-scale systems to nanomaterial based carriers. Many of these nanomaterials, however, elicit immune responses and may have cytotoxic effects both in vitro and in vivo. The naturally derived polysaccharide chitosan has emerged as a promising biodegradable material and has been utilized for many biomedical applications; nevertheless, its function is often constrained by poor solubility. Glycol chitosan, a derivative of chitosan, can be hydrophobically modified to impart amphiphilic properties that enable the self-assembly into nanoparticles in aqueous media at neutral pH. This nanoparticle system has shown initial success as a therapeutic agent in several model cell culture systems, but little is known about its stability against enzymatic degradation. Therefore, the goal of this research was to investigate the resistance of hydrophobically modified glycol chitosan against enzyme-catalyzed degradation using an in vivo simulated system containing lysozyme. To synthesize the nanoparticles, hydrophobic cholanic acid was first covalently conjugated to glycol chitosan using of N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Conjugates were purified by dialysis, lyophilized, and ultra-sonicated to form nanoparticles. Fourier transform infrared (FT-IR) spectroscopy confirmed the binding of 5beta-cholanic acid to the glycol chitosan. Particle size and stability over time were determined with dynamic light scattering (DLS), and particle morphology was evaluated by transmission electron microscopy (TEM). The average diameter of the nanoparticles was approximately 200 nm, which remained stable at 4°C for up to 10 days. Additionally, a near infrared fluorescent (NIRF) dye

Inhalation exposure to methylene chloride does not induce systemic immunotoxicity in rats.

PubMed

Warbrick, E V; Kilgour, J D; Dearman, R J; Kimber, I; Dugard, P H

2003-07-11

Methylene chloride (dichloromethane) is used in a variety of industrial applications. To date, there has been no formal assessment of immunotoxicity attributed to methylene chloride. Studies were undertaken to examine whether methylene chloride has any potential to influence the integrity of immune function. For this purpose, Sprague-Dawley rats of both genders were exposed by inhalation to a single high dose (5000 ppm) of methylene chloride for 6 h/d, 5 d/wk for 28 d. This was considered the relevant route of administration, as not only is inhalation a primary route for human exposure to methylene chloride, but, also, the chemical is absorbed rapidly via the lungs. Under these conditions of exposure, methylene chloride failed to influence absolute or relative thymus weights in either gender and produced a significant reduction in relative, but not absolute, spleen weight in female rats only. Immunocompetence was measured as a function of the ability of treated animals to mount immunoglobulin M (IgM) antibody responses to sheep red blood cells (SRBC) as determined by enzyme-linked immunosorbent assay (ELISA). Exposure to methylene chloride did not affect antibody production. Evidence indicates that under these conditions of exposure, methylene chloride did not compromise immune function.

Enhanced solubility and antioxidant activity of chlorogenic acid-chitosan conjugates due to the conjugation of chitosan with chlorogenic acid.

PubMed

Rui, Liyun; Xie, Minhao; Hu, Bing; Zhou, Li; Saeeduddin, Muhammad; Zeng, Xiaoxiong

2017-08-15

Chlorogenic acid-chitosan conjugate was synthesized by introducing of chlorogenic acid onto chitosan with the aid of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and hydroxybenzotriazole. The data of UV-vis, FT-IR and NMR for chlorogenic acid-chitosan conjugates demonstrated the successful conjugation of chlorogenic acid with chitosan. Compared to chitosan, chlorogenic acid-chitosan conjugates exhibited increased solubility in distilled water, 1% acetic acid solution (v/v) or 50% ethanol solution (v/v) containing 0.5% acetic acid. Moreover, chlorogenic acid-chitosan conjugates showed dramatic enhancements in metal ion chelating activity, total antioxidant capacity, scavenging activities on 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) and superoxide radicals, inhibitory effects on lipid peroxidation and β-carotene-linoleic acid bleaching, and protective effect on H 2 O 2 -induced oxidative injury of PC12 cells. Particularly, chlorogenic acid-chitosan conjugate exhibited higher inhibitory effects on lipid peroxidation and β-carotene-linoleic acid bleaching than chlorogenic acid. The results suggested that chlorogenic acid-chitosan conjugates could serve as food supplements to enhance the function of foods in future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of methylene chloride on microorganisms and phenanthrene mineralization in soil.

PubMed

Schwartz, Egbert; Trinh, Sinh V; Scow, Kate M

2002-01-01

This study investigated the effects of the quantity of methylene chloride, used as a carrier solvent for phenanthrene when added to soil, on phenanthrene mineralization kinetics, soil phospholipid fatty add profiles (PLFA), and phenanthrene distribution. Methylene chloride dosages of 25 microL/g soil or more resulted in an enrichment of saturated PLFAs, suggesting soil microorganisms had adjusted their cell membranes in response to the solvent. A greater fraction of phenanthrene mineralized when spiked in 5 microL/g than in 25 microL/g methylene chloride suggesting that the methylene chloride became toxic to phenanthrene-degrading organisms in soil. Phenanthrene was more equally distributed among 0.1 g soil subsamples if spiked in 25 than 5 or 1 microL methylene chloride per gram soil. Thus the amount of methylene chloride used to spike phenanthrene in soil strongly impacted the mineralization kinetics, phenanthrene distribution, and microbial community in soil. Because a variety of spiking methods are used in biodegradation research, scientists should consider the quantity of solvents used when comparing results among different studies.

Synthesis, kinetic evaluation, and utilization of a biotinylated dipeptide proline diphenyl phosphonate for the disclosure of dipeptidyl peptidase IV-like serine proteases.

PubMed

Gilmore, Brendan F; Carson, Louise; McShane, Laura L; Quinn, Derek; Coulter, Wilson A; Walker, Brian

2006-08-18

In this study, we report on the synthesis, kinetic characterisation, and application of a novel biotinylated and active site-directed inactivator of dipeptidyl peptidase IV (DPP-IV). Thus, the dipeptide-derived proline diphenyl phosphonate NH(2)-Glu(biotinyl-PEG)-Pro(P)(OPh)(2) has been prepared by a combination of classical solution- and solid-phase methodologies and has been shown to be an irreversible inhibitor of porcine DPP-IV, exhibiting an over all second-order rate constant (k(i)/K(i)) for inhibition of 1.57 x 10(3) M(-1) min(-1). This value compares favourably with previously reported rates of inactivation of DPP-IV by dipeptides containing a P(1) proline diphenyl phosphonate grouping [B. Boduszek, J. Oleksyszyn, C.M. Kam, J. Selzler, R.E. Smith, J.C. Powers, Dipeptide phophonates as inhibitors of dipeptidyl peptidase IV, J. Med. Chem. 37 (1994) 3969-3976; B.F. Gilmore, J.F. Lynas, C.J. Scott, C. McGoohan, L. Martin, B. Walker, Dipeptide proline diphenyl phosphonates are potent, irreversible inhibitors of seprase (FAPalpha), Biochem, Biophys. Res. Commun. 346 (2006) 436-446.], thus demonstrating that the incorporation of the side-chain modified (N-biotinyl-3-(2-(2-(3-aminopropyloxy)-ethoxy)-ethoxy)-propyl) glutamic acid residue at the P(2) position is compatible with inhibitor efficacy. The utilisation of this probe for the detection of both purified dipeptidyl peptidase IV and the disclosure of a dipeptidyl peptidase IV-like activity from a clinical isolate of Porphyromonas gingivalis, using established electrophoretic and Western blotting techniques previously developed by our group, is also demonstrated.

Mesoscopic Modeling of the Encapsulation of Capsaicin by Lecithin/Chitosan Liposomal Nanoparticles.

PubMed

Terrón-Mejía, Ketzasmin A; Martínez-Benavidez, Evelin; Higuera-Ciapara, Inocencio; Virués, Claudia; Hernández, Javier; Domínguez, Zaira; Argüelles-Monal, Waldo; Goycoolea, Francisco M; López-Rendón, Roberto; Gama Goicochea, Armando

2018-06-12

The transport of hydrophobic drugs in the human body exhibits complications due to the low solubility of these compounds. With the purpose of enhancing the bioavailability and biodistribution of such drugs, recent studies have reported the use of amphiphilic molecules, such as phospholipids, for the synthesis of nanoparticles or nanocapsules. Given that phospholipids can self-assemble in liposomes or micellar structures, they are ideal candidates to function as vehicles of hydrophobic molecules. In this work, we report mesoscopic simulations of nanoliposomes, constituted by lecithin and coated with a shell of chitosan. The stability of such structures and the efficiency of the encapsulation of capsaicin, as well as the internal and superficial distribution of capsaicin and chitosan inside the nanoliposome, were analyzed. The characterization of the system was carried out through density maps and the potentials of mean force for the lecithin-capsaicin, lecithin-chitosan, and capsaicin-chitosan interactions. The results of these simulations show that chitosan is deposited on the surface of the nanoliposome, as has been reported in some experimental works. It was also observed that a nanoliposome of approximately 18 nm in diameter is stable during the simulation. The deposition behavior was found to be influenced by a pattern of N-acetylation of chitosan.

Bone-Induced Chondroinduction in Sheep Jamshidi Biopsy Defects with and without Treatment by Subchondral Chitosan-Blood Implant: 1-Day, 3-Week, and 3-Month Repair.

PubMed

Bell, Angela D; Lascau-Coman, Viorica; Sun, Jun; Chen, Gaoping; Lowerison, Mark W; Hurtig, Mark B; Hoemann, Caroline D

2013-04-01

Delivery of chitosan to subchondral bone is a novel approach for augmented marrow stimulation. We evaluated the effect of 3 presolidified chitosan-blood implant formulations on osteochondral repair progression compared with untreated defects. In N = 5 adult sheep, six 2-mm diameter Jamshidi biopsy holes were created bilaterally in the medial femoral condyle and treated with presolidified chitosan-blood implant with fluorescent chitosan tracer (10 kDa, 40 kDa, or 150k Da chitosan, left knee) or left to bleed (untreated, right knee). Implant residency and osteochondral repair were assessed at 1 day (N = 1), 3 weeks (N = 2), or 3 months (N = 2) postoperative using fluorescence microscopy, histomorphometry, stereology, and micro-computed tomography. Chitosan implants were retained in 89% of treated Jamshidi holes up to 3 weeks postoperative. At 3 weeks, biopsy sites were variably covered by cartilage flow, and most bone holes contained cartilage flow fragments and heterogeneous granulation tissues with sparse leukocytes, stromal cells, and occasional adipocytes (volume density 1% to 3%). After 3 months of repair, most Jamshidi bone holes were deeper, remodeling at the edges, filled with angiogenic granulation tissue, and lined with variably sized chondrogenic foci fused to bone trabeculae or actively repairing bone plate. The 150-kDa chitosan implant elicited more subchondral cartilage formation compared with 40-kDa chitosan-treated and control defects (P < 0.05, N = 4). Treated defects contained more mineralized repair tissue than control defects at 3 months (P < 0.05, N = 12). Bone plate-induced chondroinduction is an articular cartilage repair mechanism. Jamshidi biopsy repair takes longer than 3 months and can be influenced by subchondral chitosan-blood implant.

Effectiveness of chitosan against wine-related microorganisms.

PubMed

Bağder Elmaci, Simel; Gülgör, Gökşen; Tokatli, Mehmet; Erten, Hüseyin; İşci, Asli; Özçelik, Filiz

2015-03-01

The antimicrobial action of chitosan against wine related microorganisms, including Lactobacillus plantarum, Saccharomyces cerevisiae, Oeonococcus oeni, Lactobacillus hilgardii, Brettanomyces bruxellensis, Hanseniaspora uvarum and Zygosaccharomyces bailii was examined in laboratory media. In order to assess the potential applicability of chitosan as a microbial control agent for wine, the effect of chitosan, applied individually and/or in combination with sulphur dioxide (SO2), on the growth of microorganisms involved in various stages of winemaking and on the fermentative performance of S. cerevisiae was investigated. Of the seven wine-related microorganisms studied, S. cerevisiae exhibited the strongest resistance to antimicrobial action of chitosan in laboratory media with a minimum inhibitory concentration (MIC) greater than 2 g/L. L. hilgardii, O. oeni and B. bruxellensis were the most susceptible to chitosan since they were completely inactivated by chitosan at 0.2 g/L. The MIC of chitosan for L. plantarum, H. uvarum and Z. bailii was 2, 0.4 and 0.4 g/L, respectively. In wine experiments, it was found that chitosan had a retarding effect on alcoholic fermentation without significantly altering the viability and the fermentative performance of S. cerevisiae. With regard to non-Saccharomyces yeasts (H. uvarum and Z. bailii) involved in winemaking, the early deaths of these yeasts in mixed cultures with S. cerevisiae were not probably due to the antimicrobial action of chitosan but rather due to ethanol produced by the yeasts. The complex interactions between chitosan and wine ingredients as well as microbial interactions during wine fermentation considerably affect the efficacy of chitosan. It was concluded that chitosan was worthy of further investigation as an alternative or complementary preservative to SO2 in wine industry.

Alkyl chitosan film-high strength, functional biomaterials.

PubMed

Lu, Li; Xing, Cao; Xin, Shen; Shitao, Yu; Feng, Su; Shiwei, Liu; Fusheng, Liu; Congxia, Xie

2017-11-01

Biofilm with strong tensile strength is a topic item in the area of tissue engineering, medicine engineering, and so forth. Here we introduced an alkyl chitosan film with strong tensile strength and its possibility for an absorbable anticoagulation material in vivo was tested in the series of blood test, such as dynamic coagulation time, plasma recalcification time and hemolysis. Alkyl chitosan film was a better biomaterial than traditional chitosan film in the anticoagulation, tissue compatibility and cell compatibility. The unique trait of alkyl chitosan film may be for its greater contact angle and hydrophobicity ability to reduce the adsorption capacity for the blood component and the activity of fibrinolytic enzymes, enhance the antibacterial capacity than chitosan film. Moreover, none of chitosan film or butyl chitosan film exhibited quick inflammation or other disadvantage and degraded quickly by implanted test. Therefore, Alkyl chitosan film is of prospective properties as an implantable, absorbable agent for tissue heals, and this material need further research. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3034-3041, 2017. © 2017 Wiley Periodicals, Inc.

Removal of Arsenic (V) from Aqueous Solutions Using Chitosan-Red Scoria and Chitosan-Pumice Blends.

PubMed

Asere, Tsegaye Girma; Mincke, Stein; De Clercq, Jeriffa; Verbeken, Kim; Tessema, Dejene A; Fufa, Fekadu; Stevens, Christian V; Du Laing, Gijs

2017-08-09

In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch-Rs) and chitosan: pumice (Ch-Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm ( R ² > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water.

Effect of lipiodol and methylene blue on the thoracoscopic preoperative positioning.

PubMed

Zhang, Chuan-Yu; Yu, Hua-Long; Liu, Shi-He; Jiang, Gang; Wang, Yong-Jie

2015-01-01

The aim of this study was to compare and analyze the site-specific accuracy of mixture of lipiodol and methylene blue (MLM) (0.6 ml, 1:5) and pure methylene blue (0.5 ml) on the rabbit lungs. In this study, CT-guided percutaneous injection of MLM and methylene blue. Compare the staining degree by biopsy of lung tissue. Use 4 points system to evaluate the site-specific accuracy at 6h and 24 h after injection. For MLM, evaluate its radiopacity by radiation. When evaluate the positioning, 2 points mean acceptable, 3 points mean excellent. The results indicated that the staining range of MLM is obvious less than that of methylene blue (0.6 vs. 1.0 cm, P<0.01), but the staining capacity of MLM is higher than that of methylene blue (2.8 vs. 2.2, P = 0.01). About the staining abilities which are evaluated as excellent, MLM group accounts for 81%, methylene blue group accounts for 38% (P = 0.011). About the radiopacity which are evaluated as acceptable or excellent, MLM group accounts for 62%. With good direct vision, the suitable positioning rate of MLM can be 100%, which is better than that of methylene blue. In conclusion, percutaneous injection of MLM can be used to lung positioning. The result shows that use MLM is better than only using methylene blue. But it is necessary to do the investigation in human beings in order to confirm the feasibility of its clinical application.

Effect of lipiodol and methylene blue on the thoracoscopic preoperative positioning

PubMed Central

Zhang, Chuan-Yu; Yu, Hua-Long; Liu, Shi-He; Jiang, Gang; Wang, Yong-Jie

2015-01-01

The aim of this study was to compare and analyze the site-specific accuracy of mixture of lipiodol and methylene blue (MLM) (0.6 ml, 1:5) and pure methylene blue (0.5 ml) on the rabbit lungs. In this study, CT-guided percutaneous injection of MLM and methylene blue. Compare the staining degree by biopsy of lung tissue. Use 4 points system to evaluate the site-specific accuracy at 6h and 24 h after injection. For MLM, evaluate its radiopacity by radiation. When evaluate the positioning, 2 points mean acceptable, 3 points mean excellent. The results indicated that the staining range of MLM is obvious less than that of methylene blue (0.6 vs. 1.0 cm, P<0.01), but the staining capacity of MLM is higher than that of methylene blue (2.8 vs. 2.2, P = 0.01). About the staining abilities which are evaluated as excellent, MLM group accounts for 81%, methylene blue group accounts for 38% (P = 0.011). About the radiopacity which are evaluated as acceptable or excellent, MLM group accounts for 62%. With good direct vision, the suitable positioning rate of MLM can be 100%, which is better than that of methylene blue. In conclusion, percutaneous injection of MLM can be used to lung positioning. The result shows that use MLM is better than only using methylene blue. But it is necessary to do the investigation in human beings in order to confirm the feasibility of its clinical application. PMID:26221301

Synthesis and evaluation on pH- and temperature-responsive chitosan-p(MAA-co-NIPAM) hydrogels.

PubMed

Rasib, S Z M; Ahmad, Z; Khan, A; Akil, H M; Othman, M B H; Hamid, Z A A; Ullah, F

2018-03-01

In this study, chitosan-poly(methacrylic acid-co-N-isopropylacrylamide) [chitosan-p(MAA-co-NIPAM)] hydrogels were synthesized by emulsion polymerization. In order to be used as a carrier for drug delivery systems, the hydrogels had to be biocompatible, biodegradable and multi-responsive. The polymerization was performed by copolymerize MAA and NIPAM with chitosan polymer to produce a chitosan-based hydrogel. Due to instability during synthesis and complexity of components to produce the hydrogel, further study at different times of reaction is important to observe the synthesis process, the effect of end product on swelling behaviour and the most important is to find the best way to control the hydrogel synthesis in order to have an optimal swelling behaviour for drug release application. Studied by using Fourier transform infra-red (FTIR) spectroscopy found that, the synthesized was successfully produced stable chitosan-based hydrogel with PNIPAM continuously covered the outer surface of hydrogel which influenced much on the stability during synthesis. The chitosan and PMAA increased the zeta potential of the hydrogel and the chitosan capable to control shrinkage above human body temperature. The chitosan-p(MAA-co-NIPAM) hydrogels also responses to pH and temperature thus improved the ability to performance as a drug carrier. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanisms of methylene blue stimulation of the hexose monophosphate shunt in erythrocytes.

PubMed

Metz, E N; Balcerzak, P; Sagone, A L

1976-10-01

The response of the hexose monophosphate shunt in erythrocytes was studied with the ionization chamber-electrometer apparatus to measure continuously 14CO2 derived from 14C-labeled substrates. The effect of methylene blue at high (0.1 mM) and low (1 muM) concentrations was evaluated under different gas mixtures; air, carbon monoxide, and 6% carbon monoxide in air. The latter gas mixture results in nearly 100% carboxyhemoglobin but provides a physiologic partial pressure of oxygen. The extent to which pentose is recycled through the shunt in response to methylene blue stimulation was examined with radioactive glucose substrates labeled on the first, second, and third carbon positions. Generation of hydrogen peroxide after stimulation of erythrocytes with methylene blue was evaluated by the catalase-aminotriazole trapping technique, [14C]formate oxidation, and oxidation of reduced glutatione. Stimulation of the shunt with 1 muM methylene blue was markedly impaired in the absence of oxyhemoglobin, but stimulation with 0.1 mM methylene blue was only slightly impaired under the carbon monoxide-air mixture. The higher concentration of methylene blue produced evidence of hydrogen peroxide generation of all three techniques. Despite the evidence for the involvement of oxygen, oxyhemoglobin, and hydrogen peroxide in the response to methylene blue, cells containing methemoglobin induced by sodium nitrite or from a patient with congenital methemoglobinemia responded normally to methylene blue in the absence of oxygen. These experiments indicate that the reactions induced by methylene blue in erythrocytes are more complex than generally thought and that high concentrations are associated with production of peroxide.

Emerging Biomedical Applications of Nano-Chitins and Nano-Chitosans Obtained via Advanced Eco-Friendly Technologies from Marine Resources

PubMed Central

Muzzarelli, Riccardo A. A.; El Mehtedi, Mohamad; Mattioli-Belmonte, Monica

2014-01-01

The present review article is intended to direct attention to the technological advances made in the 2010–2014 quinquennium for the isolation and manufacture of nanofibrillar chitin and chitosan. Otherwise called nanocrystals or whiskers, n-chitin and n-chitosan are obtained either by mechanical chitin disassembly and fibrillation optionally assisted by sonication, or by e-spinning of solutions of polysaccharides often accompanied by poly(ethylene oxide) or poly(caprolactone). The biomedical areas where n-chitin may find applications include hemostasis and wound healing, regeneration of tissues such as joints and bones, cell culture, antimicrobial agents, and dermal protection. The biomedical applications of n-chitosan include epithelial tissue regeneration, bone and dental tissue regeneration, as well as protection against bacteria, fungi and viruses. It has been found that the nano size enhances the performances of chitins and chitosans in all cases considered, with no exceptions. Biotechnological approaches will boost the applications of the said safe, eco-friendly and benign nanomaterials not only in these fields, but also for biosensors and in targeted drug delivery areas. PMID:25415349

Post-Session Administration of USP Methylene Blue Facilitates the Retention of Pathological Fear Extinction and Contextual Memory in Phobic Adults

PubMed Central

Telch, Michael J.; Bruchey, Aleksandra K.; Rosenfield, David; Cobb, Adam R.; Smits, Jasper; Pahl, Sandra; Gonzalez-Lima, F.

2015-01-01

Objective Preclinical studies have shown that low-dose USP methylene blue increases mitochondrial cytochrome oxidase activity in the brain and improves memory retention after learning tasks, including fear extinction. We report on the first controlled experiment to examine the memory-enhancing effects of post-training methylene blue administration on retention of fear extinction and contextual memory following fear extinction training. Method Adults (N = 42) displaying marked claustrophobic fear were randomized to double-blind administration of 260 mg of methylene blue versus placebo immediately following six five-minute extinction trials to an enclosed chamber. Retesting occurred one month later to assess fear renewal as indexed by peak fear during exposure to a non-trained enclosed chamber with the prediction that methylene blue's effects would vary as a function of fear reduction achieved during extinction training. Incidental contextual memory was assessed 1 and 30 days after training to assess the cognitive enhancing effects of methylene blue independent of its effects on fear attenuation. Results Consistent with predictions, participants displaying low end fear at post-training showed significantly less fear at follow-up if they received methylene blue post-training relative to placebo. In contrast, participants displaying moderate to high levels of post-training fear tended to fare worse at follow-up relative to placebo. Methylene blue's enhancement of contextual memory was unrelated to initial or post-training claustrophobic fear. Conclusions Methylene blue enhances memory and the retention of fear extinction when administered after a successful exposure session, but may have a deleterious effect on extinction when administered after an unsuccessful exposure session. PMID:25018057

Structure of the Escherichia coli phosphonate binding protein PhnD and rationally optimized phosphonate biosensors.

PubMed

Alicea, Ismael; Marvin, Jonathan S; Miklos, Aleksandr E; Ellington, Andrew D; Looger, Loren L; Schreiter, Eric R

2011-12-02

The phnD gene of Escherichia coli encodes the periplasmic binding protein of the phosphonate (Pn) uptake and utilization pathway. We have crystallized and determined structures of E. coli PhnD (EcPhnD) in the absence of ligand and in complex with the environmentally abundant 2-aminoethylphosphonate (2AEP). Similar to other bacterial periplasmic binding proteins, 2AEP binds near the center of mass of EcPhnD in a cleft formed between two lobes. Comparison of the open, unliganded structure with the closed 2AEP-bound structure shows that the two lobes pivot around a hinge by ~70° between the two states. Extensive hydrogen bonding and electrostatic interactions stabilize 2AEP, which binds to EcPhnD with low nanomolar affinity. These structures provide insight into Pn uptake by bacteria and facilitated the rational design of high signal-to-noise Pn biosensors based on both coupled small-molecule dyes and autocatalytic fluorescent proteins. Copyright © 2011 Elsevier Ltd. All rights reserved.

Structure of the Escherichia coli Phosphonate Binding Protein PhnD and Rationally Optimized Phosphonate Biosensors

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

Alicea, Ismael; Marvin, Jonathan S.; Miklos, Aleksandr E.

2012-09-17

The phnD gene of Escherichia coli encodes the periplasmic binding protein of the phosphonate (Pn) uptake and utilization pathway. We have crystallized and determined structures of E. coli PhnD (EcPhnD) in the absence of ligand and in complex with the environmentally abundant 2-aminoethylphosphonate (2AEP). Similar to other bacterial periplasmic binding proteins, 2AEP binds near the center of mass of EcPhnD in a cleft formed between two lobes. Comparison of the open, unliganded structure with the closed 2AEP-bound structure shows that the two lobes pivot around a hinge by {approx}70{sup o} between the two states. Extensive hydrogen bonding and electrostatic interactionsmore » stabilize 2AEP, which binds to EcPhnD with low nanomolar affinity. These structures provide insight into Pn uptake by bacteria and facilitated the rational design of high signal-to-noise Pn biosensors based on both coupled small-molecule dyes and autocatalytic fluorescent proteins.« less

In vitro and in vivo chitosan membranes testing for peripheral nerve reconstruction.

PubMed

Simões, M J; Gärtner, A; Shirosaki, Y; Gil da Costa, R M; Cortez, P P; Gartnër, F; Santos, J D; Lopes, M A; Geuna, S; Varejão, A S P; Maurício, A Colette

2011-01-01

Tissue regeneration over a large defect with a subsequent satisfactory functional recovery still stands as a major problem in areas such as nerve regeneration or bone healing. The routine technique for the reconstruction of a nerve gap is the use of autologous nerve grafting, but still with severe complications. Over the last decades several attempts have been made to overcome this problem by using biomaterials as scaffolds for guided tissue regeneration. Despite the wide range of biomaterials available, functional recovery after a serious nerve injury is still far from acceptable. Prior to the use of a new biomaterial on healing tissues, an evaluation of the host's inflammatory response is mandatory. In this study, three chitosan membranes were tested in vitro and in vivo for later use as nerve guides for the reconstruction of peripheral nerves submitted to axonotmesis or neurotmesis lesions. Chitosan membranes, with different compositions, were tested in vitro, with a nerve growth factor cellular producing system, N1E-115 cell line, cultured over each of the three membranes and differentiated for 48h in the presence of 1.5% of DMSO. The intracellular calcium concentrations of the non-differentiated and of the 48h-differentiated cells cultured on the three types of the chitosan membranes were measured to determine the cell culture viability. In vivo, the chitosan membranes were implanted subcutaneously in a rat model, and histological evaluations were performed from material retrieved on weeks 1, 2, 4 and 8 after implantation. The three types of chitosan membranes were a viable substrate for the N1E-115 cell multiplication, survival and differentiation. Furthermore, the in vivo studies suggested that these chitosan membranes are promising candidates as a supporting material for tissue engineering applications on the peripheral nerve, possibly owing to their porous structure, their chemical modifications and high affinity to cellular systems.

Development of chitosan-pullulan composite nanoparticles for nasal delivery of vaccines: in vivo studies.

PubMed

Cevher, Erdal; Salomon, Stefan K; Somavarapu, Satyanarayana; Brocchini, Steve; Alpar, H Oya

2015-01-01

Here, we aimed at developing chitosan/pullulan composite nanoparticles and testing their potential as novel systems for the nasal delivery of diphtheria toxoid (DT). All the chitosan derivatives [N-trimethyl (TMC), chloride and glutamate] and carboxymethyl pullulan (CMP) were synthesised and antigen-loaded composites were prepared by polyion complexation of chitosan and pullulan derivatives (particle size: 239-405 nm; surface charge: +18 and +27 mV). Their immunological effects after intranasal administration to mice were compared to intramuscular route. Composite nanoparticles induced higher levels of IgG responses than particles formed with chitosan derivative and antigen. Nasally administered TMC-pullulan composites showed higher DT serum IgG titre when compared with the other composites. Co-encapsulation of CpG ODN within TMC-CMP-DT nanoparticles resulted in a balanced Th1/Th2 response. TMC/pullulan composite nanoparticles also induced highest cytokine levels compared to those of chitosan salts. These findings demonstrated that TMC-CMP-DT composite nanoparticles are promising delivery system for nasal vaccination.

Methylene blue adsorption by algal biomass based materials: biosorbents characterization and process behaviour.

PubMed

Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

2007-08-17

Dead algal biomass is a natural material that serves as a basis for developing a new family of sorbent materials potentially suitable for many industrial applications. In this work an algal industrial waste from agar extraction process, algae Gelidium and a composite material obtained by immobilization of the algal waste with polyacrylonitrile (PAN) were physical characterized and used as biosorbents for dyes removal using methylene blue as model. The apparent and real densities and the porosity of biosorbents particles were determined by mercury porosimetry and helium picnometry. The methylene blue adsorption in the liquid phase was the method chosen to calculate the specific surface area of biosorbent particles as it seems to reproduce better the surface area accessible to metal ions in the biosorption process than the N2 adsorption-desorption dry method. The porous texture of the biosorbents particles was also studied. Equilibrium isotherms are well described by the Langmuir equation, giving maximum uptake capacities of 171, 104 and 74 mg g(-1), respectively for algae, algal waste and composite material. Kinetic experiments at different initial methylene blue concentrations were performed to evaluate the equilibrium time and the importance of the driving force to overcome mass transfer resistances. The pseudo-first-order and pseudo-second-order kinetic models adequately describe the kinetic data. The biosorbents used in this work proved to be promising materials for removing methylene blue from aqueous solutions.

Guided surgical debridement: staining tissues with methylene blue.

PubMed

Dorafshar, Amir H; Gitman, Marina; Henry, Ginard; Agarwal, Shailesh; Gottlieb, Lawrence J

2010-01-01

Precise surgical debridement of wounds is required to achieve wound closure. The authors describe their experience with a technique using topical methylene blue to facilitate precise surgical debridement. In this technique, methylene blue dye is applied topically to the wound surface at the onset of surgery. The stained wound site is then wiped to remove dye from the surface of normal epithelium; eschar, nonviable tissue, and granulation tissue remain stained. The methylene blue-stained tissue is surgically removed, and the newly debrided surface of the wound is assessed for adequate vascularity and biopsied to verify presence of bacteriologic balance before closure. The authors have used this technique in more than 200 wound debridements during the past year, including acute surgical or traumatic wounds, acute and subacute burn wounds, chronic granulating wounds, partially epithelialized wounds, sinus tracts, and fistulae. No adverse reactions have been noted, even on patients undergoing multiple applications through serial operations. Topical application of methylene blue to wounds with mixed tissue content helps to distinguish between viable and nonviable tissue and between epithelialized and nonepithelialized areas, facilitating more precise and complete wound debridement.

Versatile nature of hetero-chitosan based derivatives as biodegradable adsorbent for heavy metal ions; a review.

PubMed

Ahmad, Mudasir; Manzoor, Kaiser; Ikram, Saiqa

2017-12-01

The polyfunctional chitosan can act as the biological macromolecule ligand not only for the adsorption and the recovery of metal ions from an aqueous media, but also for the fabrication of novel adsorbents which shows selectivity and better adsorption properties. The unmodified chitosan itself, a single cationic polysaccharide, has hydroxyl and amine groups carrying complex properties with the metal ions. In addition, the selectivity of metal ions, the adsorption efficiency and adsorption capacity of the adsorbent can be modified chemically. This review covers the synthetic strategies of chitosan towards the synthesis of hetero-chitosan based adsorbents via chemical modifications in past two decades. It also includes how chemical modification influences the metal adsorption with N, O, S and P containing chitosan derivatives. Hope this review article provides an opportunity for researchers in the future to explore the potential of chitosan as an adsorbent for removal of metal ions from wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

Chitosan-film enhanced chitosan nerve guides for long-distance regeneration of peripheral nerves.

PubMed

Meyer, Cora; Stenberg, Lena; Gonzalez-Perez, Francisco; Wrobel, Sandra; Ronchi, Giulia; Udina, Esther; Suganuma, Seigo; Geuna, Stefano; Navarro, Xavier; Dahlin, Lars B; Grothe, Claudia; Haastert-Talini, Kirsten

2016-01-01

Biosynthetic nerve grafts are developed in order to complement or replace autologous nerve grafts for peripheral nerve reconstruction. Artificial nerve guides currently approved for clinical use are not widely applied in reconstructive surgery as they still have limitations especially when it comes to critical distance repair. Here we report a comprehensive analysis of fine-tuned chitosan nerve guides (CNGs) enhanced by introduction of a longitudinal chitosan film to reconstruct critical length 15 mm sciatic nerve defects in adult healthy Wistar or diabetic Goto-Kakizaki rats. Short and long term investigations demonstrated that the CNGs enhanced by the guiding structure of the introduced chitosan film significantly improved functional and morphological results of nerve regeneration in comparison to simple hollow CNGs. Importantly, this was detectable both in healthy and in diabetic rats (short term) and the regeneration outcome almost reached the outcome after autologous nerve grafting (long term). Hollow CNGs provide properties likely leading to a wider clinical acceptance than other artificial nerve guides and their performance can be increased by simple introduction of a chitosan film with the same advantageous properties. Therefore, the chitosan film enhanced CNGs represent a new generation medical device for peripheral nerve reconstruction. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effect of Chitosan Properties on Immunoreactivity

PubMed Central

Ravindranathan, Sruthi; Koppolu, Bhanu prasanth; Smith, Sean G.; Zaharoff, David A.

2016-01-01

Chitosan is a widely investigated biopolymer in drug and gene delivery, tissue engineering and vaccine development. However, the immune response to chitosan is not clearly understood due to contradicting results in literature regarding its immunoreactivity. Thus, in this study, we analyzed effects of various biochemical properties, namely degree of deacetylation (DDA), viscosity/polymer length and endotoxin levels, on immune responses by antigen presenting cells (APCs). Chitosan solutions from various sources were treated with mouse and human APCs (macrophages and/or dendritic cells) and the amount of tumor necrosis factor-α (TNF-α) released by the cells was used as an indicator of immunoreactivity. Our results indicate that only endotoxin content and not DDA or viscosity influenced chitosan-induced immune responses. Our data also indicate that low endotoxin chitosan (<0.01 EU/mg) ranging from 20 to 600 cP and 80% to 97% DDA is essentially inert. This study emphasizes the need for more complete characterization and purification of chitosan in preclinical studies in order for this valuable biomaterial to achieve widespread clinical application. PMID:27187416

Effect of chitosan-carvacrol coating on the quality of Pacific white shrimp during iced storage as affected by caprylic acid.

PubMed

Wang, Qianyun; Lei, Jun; Ma, Junjie; Yuan, Gaofeng; Sun, Haiyan

2018-01-01

This study aimed to investigate the effect of chitosan-carvacrol coating with or without caprylic acid (CAP) on the quality of Pacific white shrimp (Litopenaeus vannamei) during 10days of iced storage. The result showed that chitosan-carvacrol coating significantly inhibited the increase in total aerobic plate count (TPC), pH and total volatile basic nitrogen content (TVB-N) of shrimp in comparison with the control. Chitosan-carvacrol coating also delayed the melanosis formation and changes of ΔE values, and improved the texture and sensory properties of shrimp. Moreover, incorporation of CAP potentiated the efficacy of chitosan-carvacrol coating in retarding the increase of TPC and TVB-N. Incorporation of CAP into chitosan-carvacrol coating also enabled the texture characteristics of shrimp to be retained greater degrees. These results suggested that chitosan-carvacrol coating may be promising to be used as active packaging for extending the shelf life, and incorporation of CAP may enhance the efficacy of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of chitosan/poly-γ-glutamic acid/pluronic/curcumin nanoparticles in chitosan dressings for wound regeneration.

PubMed

Lin, Yu-Hsin; Lin, Jui-Hsiang; Hong, Ya-Shiuan

2017-01-01

The hydrophobic polyphenol curcumin has anti-inflammatory, antimicrobial, and wound-healing properties that warrant its pharmacological consideration. We report a curcumin nanoparticle with a tripolymeric composite that can be used as a delivery device for wound healing. The present composite nanoparticles were prepared with three biocompatible polymers of chitosan, poly-γ-glutamic acid, and pluronic using a simple ionic gelation technology. Pluronic was used to enhance the solubility of curcumin in chitosan/poly-γ-glutamic acid nanoparticles, leading to the incorporation of chitosan/poly-γ-glutamic acid/pluronic/curcumin nanoparticles into chitosan membranes, and reduced inflammation and bacterial infection during wound regeneration. Nanoparticles were of 193.1 ± 8.9 nm and had a zeta potential of 20.6 ± 2.4 mV. Moreover, in vitro analyses indicated controlled curcumin release in a simulated skin tissue model. Subsequent in vivo studies show that chitosan wound dressing containing chitosan/poly-γ-glutamic acid/pluronic/curcumin nanoparticles promoted neocollagen regeneration and tissue reconstruction. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 81-90, 2017. © 2015 Wiley Periodicals, Inc.

Effect of phosphonate treatments for sudden oak death on tanoaks in naturally infested forests

Treesearch

Matteo Garbelotto; Doug Schmidt

2013-01-01

Application of phosphonate compounds has been shown to be an effective preventive treatment for sudden oak death (SOD), caused by Phytophthora ramorum, in coast live oak (Quercus agrifolia Née) and tanoak (Notholithocarpus densiflorus Manos, Cannon & S.H. Oh). To test the effectiveness of...

Chitosan-silica hybrid porous membranes.

PubMed

Pandis, Christos; Madeira, Sara; Matos, Joana; Kyritsis, Apostolos; Mano, João F; Ribelles, José Luis Gómez

2014-09-01

Chitosan-silica porous hybrids were prepared by a novel strategy in order to improve the mechanical properties of chitosan (CHT) in the hydrogel state. The inorganic silica phase was introduced by sol-gel reactions in acidic medium inside the pores of already prepared porous scaffolds. In order to make the scaffolds insoluble in acidic media chitosan was cross-linked by genipin (GEN) with an optimum GEN concentration of 3.2 wt.%. Sol-gel reactions took place with Tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) acting as silica precursors. GPTMS served also as a coupling agent between the free amino groups of chitosan and the silica network. The morphology study of the composite revealed that the silica phase appears as a layer covering the chitosan membrane pore walls. The mechanical properties of the hybrids were characterized by means of compressive stress-strain measurements. By immersion in water the hybrids exhibit an increase in elastic modulus up to two orders of magnitude. Copyright © 2014 Elsevier B.V. All rights reserved.

Visible light induced photobleaching of methylene blue over melamine-doped TiO2 nanocatalyst

EPA Science Inventory

TiO2 doping with N-rich melamine produced a stable, active and visible light sentisized nanocatalyst that showed a remarkable efficiency towards the photobleaching of a model compound – methylene blue (MB) in aqueous solution. The photobleaching followed a mixed reaction order ki...

Study on the inclusion interaction of p-sulfonated calix[ n]arenes with Vitamin K 3 using methylene blue as a spectral probe

NASA Astrophysics Data System (ADS)

Lu, Qin; Gu, Jiashan; Yu, Huapeng; Liu, Chun; Wang, Lun; Zhou, Yunyou

2007-09-01

The characteristics of host-guest complexation between p-sulfonated calix[ n]arene ( SCnA, n = 4, 6) and Vitamin K 3 ( VK3) were investigated by fluorescence spectrometry and absorption spectrometry using methylene blue ( MB) as a probe. Interaction with MB and SCnA led to an obvious decrease in fluorescence intensity of MB, accompanying with shifts of emission peaks. Absorption peaks also showed interesting changes; however, when VK3 was added, fluorescence intensity and absorbance recovered and a slight and slow red shift was observed. The obtained results showed that the inclusion ability of p-sulphonated calix[ n]arenes towards VK3 was the order: p-sulphonated calix[6]arene ( SC6A) > p-sulphonated calix[4]arene ( SC4A). Relative mechanism was proposed to explain the inclusion process.

Study on the inclusion interaction of p-sulfonated calix[n]arenes with Vitamin K3 using methylene blue as a spectral probe.

PubMed

Lu, Qin; Gu, Jiashan; Yu, Huapeng; Liu, Chun; Wang, Lun; Zhou, Yunyou

2007-09-01

The characteristics of host-guest complexation between p-sulfonated calix[n]arene (SCnA, n = 4, 6) and Vitamin K(3) (VK(3)) were investigated by fluorescence spectrometry and absorption spectrometry using methylene blue (MB) as a probe. Interaction with MB and SCnA led to an obvious decrease in fluorescence intensity of MB, accompanying with shifts of emission peaks. Absorption peaks also showed interesting changes; however, when VK(3) was added, fluorescence intensity and absorbance recovered and a slight and slow red shift was observed. The obtained results showed that the inclusion ability of p-sulphonated calix[n]arenes towards VK(3) was the order: p-sulphonated calix[6]arene (SC6A) >p-sulphonated calix[4]arene (SC4A). Relative mechanism was proposed to explain the inclusion process.

Antimicrobial activity of chitosan and a chitosan oligomer against bacterial pathogens of warmwater fish

USDA-ARS?s Scientific Manuscript database

Aim: The antibacterial activities of chitosan (CS) and its derivative chitosan oligosaccharide lactate (COL) were evaluated against Aeromonas hydrophila, Edwardsiella ictaluri and Flavobacterium columnare, three highly pathogenic bacteria of warmwater finfish. Methods and Results: The kinetics of ce...

Methylene blue is associated with poor outcomes in vasoplegic shock.

PubMed

Weiner, Menachem M; Lin, Hung-Mo; Danforth, Dennis; Rao, Srikar; Hosseinian, Leila; Fischer, Gregory W

2013-12-01

The purpose of this study was to investigate whether patients who received methylene blue as treatment for vasoplegia during cardiac surgery with cardiopulmonary bypass had decreased morbidity and mortality. Retrospective analysis. Single tertiary care university hospital. Adult patients who suffered from vasoplegia and underwent all types of cardiac surgery with cardiopulmonary bypass at this institution between 2007 and 2008. With IRB approval, the authors reviewed the charts of the identified patients and divided them into 2 groups based on whether they had received methylene blue. Two hundred twenty-six patients were identified who met the inclusion criteria for the study. Fifty-seven of these patients had received methylene blue for vasoplegia. The authors collected data on preoperative and intraoperative variables as well as outcomes. The patients who received methylene blue had higher rates of in-hospital mortality, a compilation of morbidities, as well as renal failure and hyperbilirubinemia. A multiple logistic regression model demonstrated that receiving methylene blue was an independent predictor of in-hospital mortality (p value: 0.007, OR 4.26, 95% CI: 1.49-12.12), compilation of morbidities (p value: 0.001, OR 4.80, 95% CI: 1.85-12.43), and hyperbilirubinemia (p value:<0.001, OR 6.58, 95% CI: 2.91-14.89). Using propensity score matching, the association with morbidity was again seen but the association with mortality was not found. The current study identified the use of methylene blue as treatment for vasoplegia to be independently associated with poor outcomes. While further studies are required, a thorough risk-benefit analysis should be applied before using methylene blue and, perhaps, it should be relegated to rescue use and not as first-line therapy. Copyright © 2013 Elsevier Inc. All rights reserved.

Microfluidic Fabrication of Cell Adhesive Chitosan Microtubes

PubMed Central

Oh, Jonghyun; Kim, Keekyoung; Won, Sung Wook; Cha, Chaenyung; Gaharwar, Akhilesh; Selimović, Šeila; Bae, Hojae; Lee, Kwang Ho; Lee, Dong Hwan; Lee, Sang-Hoon; Khademhosseini, Ali

2013-01-01

Chitosan has been used as a scaffolding material in tissue engineering due to its mechanical properties and biocompatibility. With increased appreciation of the effect of micro- and nanoscale environments on cellular behavior, there is increased emphasis on generating microfabricated chitosan structures. Here we employed a microfluidic coaxial flow-focusing system to generate cell adhesive chitosan microtubes of controlled sizes by modifying the flow rates of a chitosan pre-polymer solution and phosphate buffered saline (PBS). The microtubes were extruded from a glass capillary with a 300 μm inner diameter. After ionic crosslinking with sodium tripolyphosphate (TPP), fabricated microtubes had inner and outer diameter ranges of 70-150 μm and 120-185 μm. Computational simulation validated the controlled size of microtubes and cell attachment. To enhance cell adhesiveness on the microtubes, we mixed gelatin with the chitosan pre-polymer solution and adjusted the pH values of the chitosan pre-polymer solution with gelatin and TPP. During the fabrication of microtubes, fibroblasts suspended in core PBS flow adhered to the inner surface of chitosan-gelatin microtubes. To achieve physiological pH values, we adjusted pH values of chiotsan pre-polymer solution and TPP. In particular, we were able to improve cell viability to 92% with pH values of 5.8 and 7.4 for chitosan and TPP solution respectively. Cell culturing for three days showed that the addition of the gelatin enhanced cell spreading and proliferation inside the chitosan-gelatin microtubes. The microfluidic fabrication method for ionically crosslinked chitosan microtubes at physiological pH can be compatible with a variety of cells and used as a versatile platform for microengineered tissue engineering. PMID:23355068

Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts

DOE PAGES

Shaffer, David W.; Xie, Yan; Szalda, David J.; ...

2017-09-24

Here, a critical step in creating an artificial photosynthesis system for energy storage is designing catalysts that can thrive in an assembled device. Single-site catalysts have an advantage over bimolecular catalysts because they remain effective when immobilized. Hybrid water oxidation catalysts described here, combining the features of single-site bis-phosphonate catalysts and fast bimolecular bis-carboxylate catalysts, have reached turnover frequencies over 100 s –1, faster than both related catalysts under identical conditions. The new [(bpHc)Ru(L) 2] (bpH 2cH = 2,2'-bipyridine-6-phosphonic acid-6'-carboxylic acid, L = 4-picoline or isoquinoline) catalysts proceed through a single-site water nucleophilic attack pathway. The pendant phosphonate base mediatesmore » O–O bond formation via intramolecular atom-proton transfer with a calculated barrier of only 9.1 kcal/mol. Additionally, the labile carboxylate group allows water to bind early in the catalytic cycle, allowing intramolecular proton-coupled electron transfer to lower the potentials for oxidation steps and catalysis. That a single-site catalyst can be this fast lends credence to the possibility that the oxygen evolving complex adopts a similar mechanism.« less

Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts

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

Shaffer, David W.; Xie, Yan; Szalda, David J.

Here, a critical step in creating an artificial photosynthesis system for energy storage is designing catalysts that can thrive in an assembled device. Single-site catalysts have an advantage over bimolecular catalysts because they remain effective when immobilized. Hybrid water oxidation catalysts described here, combining the features of single-site bis-phosphonate catalysts and fast bimolecular bis-carboxylate catalysts, have reached turnover frequencies over 100 s –1, faster than both related catalysts under identical conditions. The new [(bpHc)Ru(L) 2] (bpH 2cH = 2,2'-bipyridine-6-phosphonic acid-6'-carboxylic acid, L = 4-picoline or isoquinoline) catalysts proceed through a single-site water nucleophilic attack pathway. The pendant phosphonate base mediatesmore » O–O bond formation via intramolecular atom-proton transfer with a calculated barrier of only 9.1 kcal/mol. Additionally, the labile carboxylate group allows water to bind early in the catalytic cycle, allowing intramolecular proton-coupled electron transfer to lower the potentials for oxidation steps and catalysis. That a single-site catalyst can be this fast lends credence to the possibility that the oxygen evolving complex adopts a similar mechanism.« less

Gd-DTPA Adsorption on Chitosan/Magnetite Nanocomposites

NASA Astrophysics Data System (ADS)

Pylypchuk, Ie. V.; Kołodyńska, D.; Kozioł, M.; Gorbyk, P. P.

2016-03-01

The synthesis of the chitosan/magnetite nanocomposites is presented. Composites were prepared by co-precipitation of iron(II) and iron(III) salts by aqueous ammonia in the 0.1 % chitosan solution. It was shown that magnetite synthesis in the chitosan medium does not affect the magnetite crystal structure. The thermal analysis data showed 4.6 % of mass concentration of chitosan in the hybrid chitosan/magnetite composite. In the concentration range of initial Gd-DTPA solution up to 0.4 mmol/L, addition of chitosan to magnetite increases the adsorption capacity and affinity to Gd-DTPA complex. The Langmuir and Freundlich adsorption models were applied to describe adsorption processes. Nanocomposites were characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and specific surface area determination (ASAP) methods.

Removal of p-alkylphenols from aqueous solutions by combined use of mushroom tyrosinase and chitosan beads.

PubMed

Yamada, Kazunori; Inoue, Tomoaki; Akiba, Yuji; Kashiwada, Ayumi; Matsuda, Kiyomi; Hirata, Mitsuo

2006-10-01

Enzymatic removal of p-alkylphenols from aqueous solutions was investigated through the two-step approach, the quinone conversion of p-alkylphenols with mushroom tyrosinase (EC 1.14.18.1) and the subsequent adsorption of quinone derivatives enzymatically generated on chitosan beads at pH 7.0 and 45 degrees C as the optimum conditions. This technique is quite effective for removal of various p-alkylphenols from an aqueous solution. The % removal values of 97-100% were obtained for p-n-alkylphenols with carbon chain lengths of 5 to 9. In addition, removal of other p-alkylphenols was enhanced by increasing either the tyrosinase concentration or the amount of added chitosan beads, and their % removal values reached >93 except for 4-tert-pentylphenol. This technique was also applicable to remove 4-n-octylphenol (4NOP) and 4-n-nonylphenol (4NNP) as suspected endocrine disrupting chemicals. The reaction of quinone derivatives enzymatically generated with the chitosan's amino groups was confirmed by the appearance of peaks for UV-visible spectrum measurements of the chitosan films incubated in the p-alkylphenol and tyrosinase mixture solutions. In addition, 4-tert-pentylphenol underwent tyrosinase-catalyzed oxidation in the presence of hydrogen peroxide.

Quirks of dye nomenclature. 8. Methylene blue, azure and violet.

PubMed

Cooksey, C J

2017-01-01

Methylene blue was synthesized in 1877 and soon found application in medicine, staining for microscopy and as an industrial dye and pigment. An enormous literature has accumulated since its introduction. Early on, it was known that methylene blue could be degraded easily by demethylation; consequently, the purity of commercial samples often was low. Therefore, demethylation products, such as azures and methylene violet, also are considered here. The names and identity of the components, their varying modes of manufacture, analytical methods and their contribution to biological staining are discussed.

Effects of chitosan-based coatings containing peppermint essential oil on the quality of post-harvest papaya fruit

USDA-ARS?s Scientific Manuscript database

Edible coatings comprised of antimicrobial polymers based on chitosan are promising technologies to preserve post-harvest fruit quality. In this study, we investigated the potential utility of a coating made from chitosan modified by N-acylation with fatty acid to preserve post-harvest papaya qualit...

pH influences the biocompatibility of methylene blue solutions.

PubMed

Gusman, David Jonathan Rodrigues; Cintra, Luciano Tavares Angelo; Novaes, Vivian Cristina Noronha; Matheus, Henrique Rinaldi; de Araujo, Nathália Januario; de Almeida, Juliano Milanezi

2018-01-01

The aim of this study was to investigate the biocompatibility of methylene blue at different pH levels through the method of implantation in subcutaneous tissue. Eighty-four sterilized polyethylene tubes were allocated in the subcutaneous tissue of 28 rats, each one receiving four tubes, set into four groups: group tube (G-T)-empty tube, fibrin group (G-F)-tube filled with fibrin sponge, group methylene blue pH 7 (G-MB/pH 7)-tube filled with fibrin sponge soaked by methylene blue (100 μg/ml) at pH 7.0, and group methylene blue pH 1 (G-MB/pH 1)-tube filled with fibrin sponge and soaked by methylene blue (100 μg/ml) at pH 1.0. After 7, 15, and 30 days, seven animals from each group were euthanized, and the tubes involved by the surrounding tissue were removed and fixed with 4% buffered formaldehyde solution. The collected pieces were processed and histological sections (4 μm) were stained with hematoxylin and eosin and analyzed by light microscopy. Scores were assigned to analysis of histopathologic parameters. The results were statistically analyzed by the Kruskal-Wallis test (p ≤ 0.05). At 7 and 30 days, the G-MB/pH 1 group showed no significant difference in the G-T control group, while G-MB/pH 7 had a significant increase on tissue reaction, also when compared to G-T. At 15 days, there was no statistical difference between the groups. Within the limits of this study, it is concluded that methylene blue at pH 1.0 provides better biocompatibility than at pH 7.0.

Analogues of methotrexate and aminopterin with gamma-methylene and gamma-cyano substitution of the glutamate side chain: synthesis and in vitro biological activity.

PubMed

Rosowsky, A; Bader, H; Freisheim, J H

1991-01-01

Analogues of methotrexate (MTX) and aminopterin (AMT) modified at the gamma-position of the glutamate side chain were synthesized and evaluated as dihydrofolate reductase (DHFR) inhibitors and tumor cell growth inhibitors. Condesations of 4-amino-4-deoxy-N10-methylpteroic acid (mAPA) with dimethyl DL-4-methyleneglutamate in the presence of diethyl phosphorocyanidate (DEPC) followed by alkaline hydrolysis yielded N-(4-amino-4-deoxy-N10-methylpteroyl)-DL-4-methyleneglutamic acid (gamma-methyleneMTX). Condensation of 4-amino-4-deoxy-N10-formylpteroic acid (fAPA) with dimethyl-DL-4-methyleneglutamate by the mixed carboxylic-carbonic anhydride method yielded N-4-amino-4-deoxypteroyl)-DL-4-methyleneglutamic acid (gamma-methyleneAMT). Also prepared via DEPC coupling was a mixture of the four possible diastereomers of N-(4-amino-4-deoxy-N10-methylpteroyl)-4-cyanoglutamic acid (gamma-cyanoMTX). The requisite intermediate gamma-tert-butyl alpha-methyl 4-cyanoglutamate, as a DL-threo/DL-erythro mixture, was prepared from methyl N alpha-Boc-O-tosyl-L-serinate by reaction with sodium tert-butyl cyanoacetate followed by mild trifluoroacetic treatment to selectively remove the Boc group. The gamma-methylene derivatives of MTX and AMT are attractive because of their potential to act as Michael acceptors within the DHFR active site. gamma-CyanoMTX may be viewed as a congener of the nonpolyglutamated MTX analogue gamma-fluoroMTX. In vitro bioassay data for the gamma-methylene and gamma-cyano compounds support the idea that the active site of DHFR, already known for its ability to tolerate modification of the gamma-carboxyl group of MTX and AMT, can likewise accommodate substitution on the gamma-carbon itself.

Recognition of sentinel lymph nodes in patients with papillary thyroid cancer by nano-carbon and methylene blue.

PubMed

Liu, Fangzhou; Zhu, Yan; Qian, Yichuan; Zhang, Jia; Zhang, Yu; Zhang, Yuan

2017-01-01

To compare the accuracy and feasibility of methylene blue and nano-carbon in clinical tracing of sentinel lymph nodes (SLNs) in patients with papillary thyroid cancer (PTC). Ninety-six PTC patients were selected and randomly divided into a methylene blue group and a nano-carbon group (n=48). During surgery, tracer agent was injected around the tumor, and SLNs were resected and subjected to frozen pathological examination. The results were compared with those of routine pathological examination after surgery. Latent lymph node metastasis (level VI and lateral neck) was detected in both groups, with neck distribution of SLNs. There was no significant difference in the detection rate or accuracy of SLNs between two groups (P>0.05). The incorrect resection rate of parathyroid gland and incidence of temporary hypoparathyroidism in the methylene blue group were significantly higher than those of the nano-carbon group (t=4.137, P<0.05). The state of PTC lymph nodes can be well evaluated by SLN biopsy using both methylene blue and nano-carbon as tracers, but using nano-carbon has a lower incidence rate of parathyroid injury, with great clinical prospects accordingly.

Biodegradable chitosan nanogels crosslinked with genipin.

PubMed

Arteche Pujana, Maite; Pérez-Álvarez, Leyre; Cesteros Iturbe, Luis Carlos; Katime, Issa

2013-05-15

Chitosan nanoparticles crosslinked with genipin were prepared by reverse microemulsion that allowed to obtain highly monodisperse (3-20 nm by TEM) nanogels. The incorporation of genipin into chitosan was confirmed and quantitatively evaluated by UV-vis and (1)H NMR. Loosely crosslinked chitosan networks showed higher water solubility at neutral pHs than pure chitosan. The hydrodynamic diameter of the genipin-chitosan nanogels ranged from 270 to 390 nm and no remarkable differences were found when the crosslinking degree was varied. The hydrodynamic diameters of the nanoparticles increased slightly at acidic pH and the protonation of ionizable amino groups with the pH was confirmed by the zeta potential measurements. The biocompatible and biodegradable nature, as well as the colloidal and monodisperse particle size of the prepared nanogels, make them attractive candidates for a large variety of biomedical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Antimicrobial and Physicochemical Characterization of Biodegradable, Nitric Oxide-Releasing Nanocellulose-Chitosan Packaging Membranes.

PubMed

Sundaram, Jaya; Pant, Jitendra; Goudie, Marcus J; Mani, Sudhagar; Handa, Hitesh

2016-06-29

Biodegradable composite membranes with antimicrobial properties consisting of nanocellulose fibrils (CNFs), chitosan, and S-nitroso-N-acetyl-d-penicillamine (SNAP) were developed and tested for food packaging applications. As a nitric oxide donor, SNAP was encapsulated into completely dispersed chitosan in 100 mL of 0.1 N acetic acid and was thoroughly mixed with CNFs to produce a composite membrane. The fabricated membranes had a uniform dispersion of chitosan and SNAP within the CNFs, which was confirmed through scanning electron microscopy (SEM) micrographs and a chemiluminescence nitric oxide analyzer. The membranes prepared without SNAP showed lower water vapor permeability than that of the membranes with SNAP. The addition of SNAP resulted in a decrease in Young's modulus for both two- and three-layer membrane configurations. Antimicrobial property evaluation of SNAP-incorporated membranes showed an effective zone of inhibition against bacterial strains of Enterococcus faecalis, Staphylococcus aureus, and Listeria monocytogenes and demonstrated its potential applications for food packaging.

Influence of chitosan structure on the formation and stability of DNA-chitosan polyelectrolyte complexes.

PubMed

Strand, Sabina P; Danielsen, Signe; Christensen, Bjørn E; Vårum, Kjell M

2005-01-01

The interactions between DNA and chitosans varying in fractional content of acetylated units (FA), degree of polymerization (DP), and degree of ionization were investigated by several techniques, including an ethidium bromide (EtBr) fluorescence assay, gel retardation, atomic force microscopy, and dynamic and electrophoretic light scattering. The charge density of the chitosan and the number of charges per chain were found to be the dominating factors for the structure and stability of DNA-chitosan complexes. All high molecular weight chitosans condensed DNA into physically stable polyplexes; however, the properties of the complexes were strongly dependent on FA, and thereby the charge density of chitosan. By employing fully charged oligomers of constant charge density, it was shown that the complexation of DNA and stability of the polyplexes is governed by the number of cationic residues per chain. A minimum of 6-9 positive charges appeared necessary to provide interaction strength comparable to that of polycations. In contrast, further increase in the number of charges above 9 did not increase the apparent binding affinity as judged from the EtBr displacement assay. The chitosan oligomers exhibited a pH-dependent interaction with DNA, reflecting the number of ionized amino groups. The complexation of DNA and the stability of oligomer-based polyplexes became reduced above pH 7.4. Such pH-dependent dissociation of polyplexes around the physiological pH is highly relevant in gene delivery applications and might be one of the reasons for the high transfection activity of oligomer-based polyplexes observed.

Regioselective Sequential Modification of Chitosan via Azide-Alkyne Click Reaction: Synthesis, Characterization, and Antimicrobial Activity of Chitosan Derivatives and Nanoparticles

PubMed Central

Sarwar, Atif; Katas, Haliza; Samsudin, Siti Noradila; Zin, Noraziah Mohamad

2015-01-01

Recently, the attention of researchers has been drawn toward the synthesis of chitosan derivatives and their nanoparticles with enhanced antimicrobial activities. In this study, chitosan derivatives with different azides and alkyne groups were synthesized using click chemistry, and these were further transformed into nanoparticles by using the ionotropic gelation method. A series of chitosan derivatives was successfully synthesized by regioselective modification of chitosan via an azide-alkyne click reaction. The amino moieties of chitosan were protected during derivatization by pthaloylation and subsequently unblocked at the end to restore their functionality. Nanoparticles of synthesized derivatives were fabricated by ionic gelation to form complexes of polyanionic penta-sodium tripolyphosphate (TPP) and cationic chitosan derivatives. Particle size analysis showed that nanoparticle size ranged from 181.03 ± 12.73 nm to 236.50 ± 14.32 nm and had narrow polydispersity index and positive surface charge. The derivatives and corresponding nanoparticles were evaluated in vitro for antibacterial and antifungal activities against three gram-positive and gram-negative bacteria and three fungal strains, respectively. The minimum inhibitory concentration (MIC) of all derivatives ranged from 31.3 to 250 µg/mL for bacteria and 188 to1500 µg/mL for fungi and was lower than that of native chitosan. The nanoparticles with MIC ranging from 1.56 to 25 µg/mLfor bacteria and 94 to 750 µg/mL for fungi exhibited higher activity than the chitosan derivatives. Chitosan O-(1-methylbenzene) triazolyl carbamate and chitosan O-(1-methyl phenyl sulfide) triazolyl carbamate were the most active against the tested bacterial and fungal strains. The hemolytic assay on erythrocytes and cell viability test on two different cell lines (Chinese hamster lung fibroblast cells V79 and Human hepatic cell line WRL68) demonstrated the safety; suggesting that these derivatives could be used in future

Effect of enzymatic degradation of chitosan in polyhydroxybutyrate/chitosan/calcium phosphate composites on in vitro osteoblast response.

PubMed

Giretova, Maria; Medvecky, Lubomir; Stulajterova, Radoslava; Sopcak, Tibor; Briancin, Jaroslav; Tatarkova, Monika

2016-12-01

Polyhydroxybutyrate/chitosan/calcium phosphate composites are interesting biomaterials for utilization in regenerative medicine and they may by applied in reconstruction of deeper subchondral defects. Insufficient informations were found in recent papers about the influence of lysozyme degradation of chitosan in calcium phosphate/chitosan based composites on in vitro cytotoxicity and proliferation activity of osteoblasts. The effect of enzymatic chitosan degradation on osteoblasts proliferation was studied on composite films in which the porosity of origin 3D scaffolds was eliminated and the surface texture was modified. The significantly enhanced proliferation activity with faster population growth of osteoblasts were found on enzymatically degraded biopolymer composite films with α-tricalcium phosphate and nanohydroxyapatite. No cytotoxicity of composite films prepared from lysozyme degraded scaffolds containing a large fraction of low molecular weight chitosans (LMWC), was revealed after 10 days of cultivation. Contrary to above in the higher cytotoxicity origin untreated nanohydroxyapatite films and porous composite scaffolds. The results showed that the synergistic effect of surface distribution, morphology of nanohydroxyapatite particles, microtopography and the presence of LMWC due to chitosan degradation in composite films were responsible for compensation of the cytotoxicity of nanohydroxyapatite composite films or porous composite scaffolds.

Maillard reaction products from chitosan-xylan ionic liquid solution.

PubMed

Luo, Yuqiong; Ling, Yunzhi; Wang, Xiaoying; Han, Yang; Zeng, Xianjie; Sun, Runcang

2013-10-15

A facile method is reported to prepare Maillard reaction products (MRPs) from chitosan and xylan in co-solvent ionic liquid. UV absorbance and fluorescence changes were regarded as indicators of the occurrence of Maillard reaction. FT-IR, NMR, XRD and TG were used to investigate the structure of chitosan-xylan conjugate. The results revealed that when chitosan reacted with xylan in ionic liquid, the hydrogen bonds in chitosan were destroyed, the facts resulted in the formation of chitosan-xylan MRPs. Moreover, when the mass ratio of chitosan to xylan was 1:1, the Maillard reaction proceeded easily. In addition, relatively high antioxidant property was also noted for the chitosan-xylan conjugate with mass ratio 1:1. So the obtained chitosan-xylan MRP is a promising antioxidant agent for food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chitosan: A potential biopolymer for wound management.

PubMed

Bano, Ijaz; Arshad, Muhammad; Yasin, Tariq; Ghauri, Muhammad Afzal; Younus, Muhammad

2017-09-01

It has been seen that slow healing and non-healing wounds conditions are treatable but still challenging to humans. Wound dressing usually seeks for biocompatible and biodegradable recipe. Natural polysaccharides like chitosan have been examined for its antimicrobial and healing properties on the basis of its variation in molecular weight and degree of deacetylation. Chitosan adopts some vital characteristics for treatment of various kinds of wounds which include its bonding nature, antifungal, bactericidal and permeability to oxygen. Chitosan therefore has been modified into various forms for the treatment of wounds and burns. The purpose of this review article is to understand the exploitation of chitosan and its derivatives as wound dressings. This article will also provide a concise insight on the properties of chitosan necessary for skin healing and regeneration, particularly highlighting the emerging role of chitosan films as next generation skin substitutes for the treatment of full thickness wounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular interactions in gelatin/chitosan composite films.

PubMed

Qiao, Congde; Ma, Xianguang; Zhang, Jianlong; Yao, Jinshui

2017-11-15

Gelatin and chitosan were mixed at different mass ratios in solution forms, and the rheological properties of these film-forming solutions, upon cooling, were studied. The results indicate that the significant interactions between gelatin and chitosan promote the formation of multiple complexes, reflected by an increase in the storage modulus of gelatin solution. Furthermore, these molecular interactions hinder the formation of gelatin networks, consequently decreasing the storage modulus of polymer gels. Both hydrogen bonds and electrostatic interactions are formed between gelatin and chitosan, as evidenced by the shift of the amide-II bands of polymers. X-ray patterns of composite films indicate that the contents of triple helices decrease with increasing chitosan content. Only one glass transition temperature (T g ) was observed in composite films with different composition ratios, and it decreases gradually with an increase in chitosan proportion, indicating that gelatin and chitosan have good miscibility and form a wide range of blends. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitroreductase-triggered activation of a novel caged fluorescent probe obtained from methylene blue.

PubMed

Bae, Jungeun; McNamara, Louis E; Nael, Manal A; Mahdi, Fakhri; Doerksen, Robert J; Bidwell, Gene L; Hammer, Nathan I; Jo, Seongbong

2015-08-18

A near-infrared fluorescent probe based on methylene blue (p-NBMB) was developed for the detection of nitroreductase. Conjugating methylene blue with a p-nitrobenzyl moiety enables it to be activated by nitroreductase-catalyzed 1,6-elimination, resulting in the release of an active methylene blue fluorophore.

Understanding the mechanism of action of triazine-phosphonate derivatives as flame retardants for cotton fabrics

USDA-ARS?s Scientific Manuscript database

Countless hours of research and studies on triazine, phosphonate and their combination have provided insightful information into their flame retardant properties on polymeric systems. However, only limited number of studies shed light on the mechanism of flame retardant cotton fabrics. The purpose...

Mucoadhesive properties and interaction with P-glycoprotein (P-gp) of thiolated-chitosans and -glycol chitosans and corresponding parent polymers: a comparative study.

PubMed

Trapani, Adriana; Palazzo, Claudio; Contino, Marialessandra; Perrone, Maria Grazia; Cioffi, Nicola; Ditaranto, Nicoletta; Colabufo, Nicola Antonio; Conese, Massimo; Trapani, Giuseppe; Puglisi, Giovanni

2014-03-10

The aim of the present work was to compare the mucoadhesive and efflux pump P-glycoprotein (P-gp) interacting properties of chitosan (CS)- and glycolchitosan (GCS)-based thiomers and corresponding unmodified parent polymers. For this purpose, the glycol chitosan-N-acetyl-cysteine (GCS-NAC) and glycol chitosan-glutathione (GCS-GSH) thiomers were prepared under simple and mild conditions. Their mucoadhesive characteristics were studied by turbidimetric and zeta potential measurements. The P-gp interacting properties were evaluated measuring the effects of thiolated- and unmodified-polymers on the bidirectional transport (BA/AB) of rhodamine-123 across Caco-2 cells as well as in the calcein-AM and ATPase activity assays. Although all the thiomers and unmodified polymers showed optimal-excellent mucoadhesive properties, the best mucoadhesive performances have been obtained by CS and CS-based thiomers. Moreover, it was found that the pretreatment of Caco-2 cell monolayer with GCS-NAC or GCS restores Rho-123 cell entrance by inhibiting P-gp activity. Hence, GCS-NAC and GCS may constitute new biomaterials useful for improving the bioavailability of P-gp substrates.

[Sensitive determination of Bi3+ by spectrofluorimetry based on graphene oxide-methylene blue system].

PubMed

Zhai, Qiu-ge; Guo, Peng; Zhou, Lin; Liu, Yan-ming

2014-08-01

Graphene oxide was prepared by the modified Hummers method and characterized by field emission scanning electron microscopy. The interaction of graphene with methylene blue was studied by UV absorption, the intensity of two main absorption peaks of methylene blue decreased significantly after the fluorescence was quenched, and the energy transfer didn't occur because the overlap of the absorption spectrum of GO and the emission spectrum of MB is too small. Therefore, the fluorescence quenching of MB and GO was static. When adding a certain amount of Bi3+ in the graphene-methylene blue system, Bi3+ replaces the methylene blue from the graphene-methylene blue complexes because Bi3+ has the smaller volume and is more positively charged. The methylene blue therefore dissociates from the GO-MB complexes, resulting in the recovery of fluorescence of the system. Furthermore, the fluorescence of the system increases with the increase in the amount of Bi3+ due to the enhanced amount of MB in the system. A novel spectrofluorimetric method was therefore developed for the sensitive determination of Bi3+. Some parameters including the concentration of methylene blue, the amount of graphene oxide, the amount of nitric acid and the sequence of reagent adding were optimized to obtain higher sensitivity. The fluorescence of the system was detected at an emission wavelength of 667 nm with excitation at 690 nm. Under the optimized conditions, the concentration of Bi3+ showed good linear relationships with the fluorescence intensity in the range of 0.5-100 micromol x L(-1), with correlation coefficients of r = 0.9955. The limits of detection for Bi3+ was 1.0 x 10(-8) mol x L(-1) (S/N=3). The selectivity of the proposed method was evaluated and the results showed that 1000-fold K+, Ca+, Na+, Mg2+, Cu2+; 100-fold Fe3+, Be2+, SiO2- Al3+, Ni2+, Sb3+, NO3-, Cl-, F-, and 20-fold Pb2+, Hg2+, Cd2+ had negligible interference with the determination of Bi3+. The method has advantages of

Permeability Evaluation Through Chitosan Membranes Using Taguchi Design

PubMed Central

Sharma, Vipin; Marwaha, Rakesh Kumar; Dureja, Harish

2010-01-01

In the present study, chitosan membranes capable of imitating permeation characteristics of diclofenac diethylamine across animal skin were prepared using cast drying method. The effect of concentration of chitosan, concentration of cross-linking agent (NaTPP), crosslinking time was studied using Taguchi design. Taguchi design ranked concentration of chitosan as the most important factor influencing the permeation parameters of diclofenac diethylamine. The flux of the diclofenac diethylamine solution through optimized chitosan membrane (T9) was found to be comparable to that obtained across rat skin. The mathematical model developed using multilinear regression analysis can be used to formulate chitosan membranes that can mimic the desired permeation characteristics. The developed chitosan membranes can be utilized as a substitute to animal skin for in vitro permeation studies. PMID:21179329

Permeability evaluation through chitosan membranes using taguchi design.

PubMed

Sharma, Vipin; Marwaha, Rakesh Kumar; Dureja, Harish

2010-01-01

In the present study, chitosan membranes capable of imitating permeation characteristics of diclofenac diethylamine across animal skin were prepared using cast drying method. The effect of concentration of chitosan, concentration of cross-linking agent (NaTPP), crosslinking time was studied using Taguchi design. Taguchi design ranked concentration of chitosan as the most important factor influencing the permeation parameters of diclofenac diethylamine. The flux of the diclofenac diethylamine solution through optimized chitosan membrane (T9) was found to be comparable to that obtained across rat skin. The mathematical model developed using multilinear regression analysis can be used to formulate chitosan membranes that can mimic the desired permeation characteristics. The developed chitosan membranes can be utilized as a substitute to animal skin for in vitro permeation studies.

Cytotoxic activity of aminoderivatized cationic chitosan derivatives.

PubMed

Lee, Jung-Kul; Lim, Hyun-Soo; Kim, Jung-Hoe

2002-10-21

Chitosan derivatives were prepared by dialkylaminoalkylation and reductive amination followed by quaternization. In this study, the cytotoxic activity of the chitosan derivatives was investigated and a relationship between structure and activity is suggested. The cationic chitosan derivatives elicited dose-dependent inhibitory effects on the proliferation of tumor cell lines.

Metabolism of 4,4'-methylene-bis-2-chloroaniline (MOCA) by rats in vivo and formation of N-hydroxy MOCA by rat and human liver microsomes.

PubMed

Morton, K C; Lee, M S; Siedlik, P; Chapman, R

1988-05-01

The metabolism of 4,4'-methylene-bis-2-chloroaniline (MOCA) was investigated because it is an animal carcinogen to which humans have been exposed. In CD rats, where MOCA is a hepatocarcinogen, less than or equal to 0.2% of an oral dose of [14C]MOCA was recovered unchanged in the urine; enzymatic hydrolysis and extraction of urinary radioactivity indicated the presence of glucuronide and sulfate conjugates. In rat bile, the predominant metabolite was N-glucuronyl MOCA. Liver microsomes from male CD rats or human males (surgical specimens) were incubated in vitro with [14C] MOCA. Metabolite formation, which was dependent upon reduced pyridine nucleotides and intact microsomes, was quantitated by TLC and HPLC using appropriate chemically synthesized standards. N-Hydroxylation of MOCA occurred at a rate of 335 +/- 119 pmol/min/mg rat microsomal protein (n = 3) versus 230 or 765 (n = 2) with microsomes from humans; the product was identified by isotopic dilution for both species. The rates of 5-hydroxy-MOCA (o-aminophenol) formation were 92 +/- 33 (rats) and 7, 35 (human); rates for the benzhydrol derivative were 82 +/- 12 (rats) and 60, 160 (human). In rats, all three rates were elevated 4- to 8-fold by pretreatment with phenobarbital, which also enhanced the formation of partially characterized polar derivatives that appeared to result from oxidation and cleavage at the methylene carbon. The latter pathway typically amounted to 50-100% of the 4,4'-diamino-3,3'-dichlorobenzhydrol value in control or pretreated animals. Thus, rats metabolize MOCA extensively and the pathways include N-hydroxlation, which is regarded as an obligatory step in metabolic activation of arylamines. The presence of MOCA N-hydroxylase in human liver supports the hypothesis that exposure of humans to MOCA entails a carcinogenic risk.

Tunable passively Q-switched erbium-doped fiber laser with Chitosan/MoS2 saturable absorber

NASA Astrophysics Data System (ADS)

Ahmad, H.; Aidit, S. N.; Ooi, S. I.; Tiu, Z. C.

2018-07-01

Chitosan, an organic polymer derived from the outer skeletons of crustacean and in the cell wall of fungi is explored as polymer host to develop thin film saturable absorber (SA). As a polymer, Chitosan shows high thermal stability as well as significant transmission characteristics. The highly transparent polymer serves as a good host for SA materials, and a composite Chitosan/MoS2 thin film is demonstrated to successfully generate stable Q-switched lasing output at operating wavelength of 1561.5 nm. At maximum pump power of 280.5 mW, the generated pulse exhibits maximum pulse repetition rate and pulse energy of 79.4 kHz and 43.69 nJ respectively as well as minimum pulse width of 1.02 μs. The overall efficiency of the laser cavity with the Chitosan/MoS2 thin film SA is approximately 0.93%. These results reflect the outstanding performance of Chitosan/MoS2 SA as compared to other MoS2 SA prepared using mechanical exfoliation and optical deposition technique. Moreover, the Chitosan polymer is shown to be a highly potential host in the SA fabrication process due to its promising performance which is comparable to PVA.

Chitosan-hyaluronic acid/nano silver composite sponges for drug resistant bacteria infected diabetic wounds.

PubMed

Anisha, B S; Biswas, Raja; Chennazhi, K P; Jayakumar, R

2013-11-01

The aim of this work was to develop an antimicrobial sponge composed of chitosan, hyaluronic acid (HA) and nano silver (nAg) as a wound dressing for diabetic foot ulcers (DFU) infected with drug resistant bacteria. nAg (5-20 nm) was prepared and characterized. The nanocomposite sponges were prepared by homogenous mixing of chitosan, HA and nAg followed by freeze drying to obtain a flexible and porous structure. The prepared sponges were characterized using SEM and FT-IR. The porosity, swelling, biodegradation and haemostatic potential of the sponges were also studied. Antibacterial activity of the prepared sponges was analysed using Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Klebsiella pneumonia. Chitosan-HA/nAg composite sponges showed potent antimicrobial property against the tested organisms. Sponges containing higher nAg (0.005%, 0.01% and 0.02%) concentrations showed antibacterial activity against MRSA. Cytotoxicity and cell attachment studies were done using human dermal fibroblast cells. The nanocomposite sponges showed a nAg concentration dependent toxicity towards fibroblast cells. Our results suggest that this nanocomposite sponges could be used as a potential material for wound dressing for DFU infected with antibiotic resistant bacteria if the optimal concentration of nAg exhibiting antibacterial action with least toxicity towards mammalian cells is identified. Copyright © 2013 Elsevier B.V. All rights reserved.

Chitosan in Molecularly-Imprinted Polymers: Current and Future Prospects.

PubMed

Xu, Long; Huang, Yun-An; Zhu, Qiu-Jin; Ye, Chun

2015-08-07

Chitosan is widely used in molecular imprinting technology (MIT) as a functional monomer or supporting matrix because of its low cost and high contents of amino and hydroxyl functional groups. The various excellent properties of chitosan, which include nontoxicity, biodegradability, biocompatibility, and attractive physical and mechanical performances, make chitosan a promising alternative to conventional functional monomers. Recently, chitosan molecularly-imprinted polymers have gained considerable attention and showed significant potential in many fields, such as curbing environmental pollution, medicine, protein separation and identification, and chiral-compound separation. These extensive applications are due to the polymers' desired selectivity, physical robustness, and thermal stability, as well as their low cost and easy preparation. Cross-linkers, which fix the functional groups of chitosan around imprinted molecules, play an important role in chitosan molecularly-imprinted polymers. This review summarizes the important cross-linkers of chitosan molecularly-imprinted polymers and illustrates the cross-linking mechanism of chitosan and cross-linkers based on the two glucosamine units. Finally, some significant attempts to further develop the application of chitosan in MIT are proposed.

[Methylene blue in the treatment of vasodilatory shock: a Meta-analysis].

PubMed

Zhang, Xiongfeng; Gao, Yun; Pan, Pengfei; Wang, Yi; Li, Wenzhe; Yu, Xiangyou

2017-11-01

To investigate the clinical efficacy of methylene blue in the treatment of refractory hypotension caused by vascular paralysis during the course of vasodilatory shock. The related articles were searched by retrieving the terms using methylene blue, vascular paralysis, hemodynamics, hypotension, vasodilatory shock in CNKI, China Biomedical Literature database, Wanfang database, PubMed, Springer Link, and BIOSIS Previews database. The retrieval time was from January 1994 to June 2017. The randomized clinical trials (RCTs) which using methylene blue as the experimental group, normal saline or catecholamine as the control in the treatment of refractory hypotension caused by vascular paralysis during the course of vasodilatory shock were collected. The primary end points were mean arterial pressure (MAP) immediately or 1 hour after the methylene blue administration, and the mortality at the longest follow-up available; the secondary end point was serum lactic acid (Lac) 1 hour after the methylene blue administration. Literature screening, data extraction and quality evaluation were carried out by two researchers. Meta analysis was performed using RevMan 5.3 software. The sensitivity analysis was performed in two trials with low risk of bias. The funnel plot for MAP was performed in five relative trials to analyze the research and publication bias. Totally 269 relative articles were collected, according to the inclusion and exclusion criteria, finally 6 RCTs with 214 patients were enrolled, 108 in methylene blue group, and 106 in control group. Four of the studies were considered to have mild to moderate risk of bias, two studies of high risk of bias. The Meta-analysis demonstrated that compared with the control group, methylene blue could significantly improve MAP [mean difference (MD) = 4.87, 95% confidence interval (95%CI) = 2.61 to 7.13, P < 0.000 1], reduce the serum Lac levels (MD = -1.06, 95%CI = -1.98 to -0.14, P = 0.02), and the mortality was decreased without

Synthesis and in vitro evaluation of methotrexate conjugated O, N-carboxymethyl chitosan via peptidyl spacers

NASA Astrophysics Data System (ADS)

Li, Dan; Lu, Bo; Zhang, Hong; Huang, Zhijun; Xu, Peihu; Zheng, Hua; Yin, Yihua; Xu, Haixing; Liu, Xia; Lou, Yiceng; Zhang, Xueqiong; Xiong, Fuliang

2014-09-01

The use of methotrexate (MTX), an anticancer drug for the treatment of hematologic malignancies, has been limited in the clinical application due to its poor water solubility, high clearance rate, and lack of target specificity. To solve these problems, O, N-carboxymethyl chitosan-dipeptide-MTX conjugates have been synthesized and characterized by fourier transform infrared radiation spectroscopy and proton nuclear magnetic resonance (1H NMR). All polymeric conjugates showed satisfactory water solubility. The results of the study revealed that drug release and toxicity were affected by employing polymeric conjugation strategy and dipeptide spacers [glycylglycine (Gly-Gly), glycyl- l-phenylalanine (Gly-Phe), glycyl- l-tyrosine (Gly-Tyr)]. It has been found that drugs could be effectively loaded and released when polymeric prodrugs were combined with a dipeptide spacer. In conclusion, O, N-CMCS-dipeptide-MTX polymeric prodrugs could potentially be used as responsive drug delivery systems.

Entirely S-protected chitosan: A promising mucoadhesive excipient for metronidazole vaginal tablets.

PubMed

Lupo, Noemi; Fodor, Benjamin; Muhammad, Ijaz; Yaqoob, Muhammad; Matuszczak, Barbara; Bernkop-Schnürch, Andreas

2017-12-01

Synthesis and evaluation of an entirely S-protected chitosan as mucoadhesive excipient for vaginal drug delivery. N-acetyl-cysteine was linked to 6-mercaptonicotinamide via disulphide exchange reaction. The obtained ligand, NAC-6-MNA, was subsequently attached to chitosan by carbodiimide mediated amide bond formation in two concentrations. The synthesized S-protected chitosan was chemically characterized and mucoadhesive properties and stability against oxidation were investigated. Moreover, metronidazole tablets comprising the S-protected chitosan were evaluated regarding water uptake capacity, disintegration behaviour, residence time on vaginal mucosa, release of the encapsulated drug and antimicrobial activity. S-protected chitosan displayed 160±19 (CS-MNA-160) and 320±38 (CS-MNA-320)µmol of ligand per gram of polymer. At pH 4.2, CS-MNA-160 and CS-MNA-320 showed 5.2-fold and 6.2-fold increase in mucus viscosity in comparison to unmodified chitosan (One-way ANOVA, p<.001), whereas, 9.9-fold (CS-MNA-160) and 15.6-fold (CS-MNA-320) (One-way ANOVA, p<.001) increase in viscosity was measured at pH 6. The S-protected chitosan remained stable against oxidation in presence of 0.5%v/v hydrogen peroxide. Metronidazole tablets consisting in S-protected chitosan showed prolonged residence time on vaginal mucosa and improved water uptake capacity and disintegration time in comparison to tablets consisting of unmodified chitosan. Moreover, CS-MNA-320 metronidazole tablets displayed prolonged drug release and antimicrobial activity. On the basis of the achieved results, entirely S-protected chitosan represents a promising excipient for the development of metronidazole vaginal tablets. S-protected thiomers are polymers modified with thiol groups protected by aromatic ligands and characterized by strong mucoadhesive properties and high stability against oxidation. Up to date, the entirely S-protection of thiol groups was achieved via the synthesis of the ligand 2-((2-amino-2

Fatal exposure to methylene chloride among bathtub refinishers - United States, 2000-2011.

PubMed

2012-02-24

In 2010, the Michigan Fatality Assessment and Control Evaluation program conducted an investigation into the death of a bathtub refinisher who used a methylene chloride-based paint stripping product marketed for use in aircraft maintenance. The program identified two earlier, similar deaths in Michigan. Program staff members notified CDC's National Institute for Occupational Safety and Health (NIOSH), which in turn notified the Occupational Safety and Health Administration (OSHA). In addition to the three deaths, OSHA identified 10 other bathtub refinisher fatalities associated with methylene chloride stripping agents that had been investigated in nine states during 2000-2011. Each death occurred in a residential bathroom with inadequate ventilation. Protective equipment, including a respirator, either was not used or was inadequate to protect against methylene chloride vapor, which has been recognized as potentially fatal to furniture strippers and factory workers but has not been reported previously as a cause of death among bathtub refinishers. Worker safety agencies, public health agencies, methylene chloride-based stripper manufacturers, and trade organizations should communicate the extreme hazards of using methylene chloride-based stripping products in bathtub refinishing to employers, workers, and consumers. Employers should strongly consider alternative methods of bathtub stripping and always ensure worker safety protections that reduce the risk for health hazards to acceptable levels. Employers choosing to use methylene chloride-based stripping products must comply with OSHA's standard to limit methylene chloride exposures to safe levels.

Degree of Acetylization Chitosan Gonggong Snail Shells

NASA Astrophysics Data System (ADS)

Horiza, H.; Iskandar, I.; Aldo, N.

2018-04-01

Chitosan is a polysaccharide obtained from the deacetylation of chitin, which is generally derived from crustacean animal waste and animal skins other sea. One marine animals that have compounds that can be processed chitin chitosan is derived from the snail Gonggong marine waters of Riau Islands province. The purpose of this study was to determine the degree of chitosan from the shells of snails asetilisasi Gonggong. This research is an experimental research laboratory. The results of this study indicate that the degree of chitosan shell snail deasetilisasi Gonggong is 70.27%.

Chitosan boosts the antimicrobial activity of Origanum vulgare essential oil in modified atmosphere packaged pork.

PubMed

Paparella, Antonello; Mazzarrino, Giovanni; Chaves-López, Clemencia; Rossi, Chiara; Sacchetti, Giampiero; Guerrieri, Oana; Serio, Annalisa

2016-10-01

The potential of chitosan as a possible booster of the antimicrobial activity of Origanum vulgare EO (OEO) against spoilage bacteria and Listeria monocytogenes was investigated in fresh pork meat. Pork fillets were inoculated with 3 L. monocytogenes strains, dipped either in Origanum vulgare (oregano) Essential Oil (OEO) at 2 and 4%, or in chitosan 1% alone or added with 2 and 4% OEO, then packed under modified atmosphere (70% O2, 20% CO2, 10% N2) and stored at 4 °C for 15 days. OEO did not reduce L. monocytogenes growth, while 2 Log decrease was obtained after 2 days of storage in treatments with chitosan alone or with OEO, with growth inhibition up to day 15 in samples with chitosan and OEO 4%. When OEO was combined with chitosan, total viable counts and spoilage bacteria were reduced and contained over time, particularly Pseudomonas (2.0 Log CFU/g at day 15) and Brochothrix thermosphacta (undetectable). All the treatments applied extended meat shelf-life with respect to control, whose commercial shelf-life was 10 days. Chitosan treatments enhanced L* and maintained a* values almost stable during storage. Chitosan and OEO singly applied reduced lipid oxidation (0.62-0.75 mg malondialdehyde/Kg meat) compared to control (0.99 mg malondialdehyde/Kg meat). Finally, chitosan treated samples were not recognized with respect to the control, whereas OEO gave bitter taste; chitosan with OEO instead mitigated the effect of OEO addition to meat. Chitosan combined with OEO boosts its antimicrobial activity and shows a potential for application in industrial production of fresh pork in MAP, to achieve shelf-life extension, control of L. monocytogenes growth, stability of color and protective effect from oxidation, with low sensory impact. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chitosan pretreatment for cotton dyeing with black tea

NASA Astrophysics Data System (ADS)

Campos, J.; Díaz-García, P.; Montava, I.; Bonet-Aracil, M.; Bou-Belda, E.

2017-10-01

Chitosan is used in a wide range of applications due to its intrinsic properties. Chitosan is a biopolymer obtained from chitin and among their most important aspects highlights its bonding with cotton and its antibacterial properties. In this study two different molecular weight chitosan are used in the dyeing process of cotton with black tea to evaluate its influence. In order to evaluate the effect of the pretreatment with chitosan, DSC and reflection spectrophotometer analysis are performed. The curing temperature is evaluated by the DSC analysis of cotton fabric treated with 15 g/L of chitosan, whilst the enhancement of the dyeing is evaluated by the colorimetric coordinates and the K/S value obtained spectrophotometrically. This study shows the extent of improvement of the pretreatment with chitosan in dyeing with natural products as black tea.

DEMONSTRATION OF N-METHYL PYRROLIDONE (NMP) AS A POLLUTION PREVENTION ALTERNATIVE TO PAINT STRIPPING WITH METHYLENE CHLORIDE

EPA Science Inventory

This objective of this paper is to demonstrate that NMP is a viable pollution prevention alternative to methylene chloride. Maine Corps Logistics Base (MCLB), Albany, GA, USA was the host site for the demonstration. MCLB's primary function is maintenance of military ground supp...

Swelling kinetics of spray-dried chitosan acetate assessed by magnetic resonance imaging and their relation to drug release kinetics of chitosan matrix tablets.

PubMed

Huanbutta, Kampanart; Sriamornsak, Pornsak; Limmatvapirat, Sontaya; Luangtana-anan, Manee; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide; Nunthanid, Jurairat

2011-02-01

Magnetic resonance imaging (MRI) was used to assess in situ swelling behaviors of spray-dried chitosan acetate (CSA) in 0.1N HCl, pH 6.8 and pH 5.0 Tris-HCl buffers. The in vitro drug releases from CSA matrix tablets containing the model drugs, diclofenac sodium and theophylline were investigated in all media using USP-4 apparatus. The effect of chitosan molecular weight, especially in pH 6.8 Tris-HCl, was also studied. In 0.1N HCl, the drug release from the matrix tablets was the lowest in relation to the highest swelling of CSA. The swelling kinetics in Tris-HCl buffers are Fickian diffusion according to their best fit to Higuchi's model as well as the drug release kinetics in all the media. The high swelling rate (k(s)(')) was found to delay the drug release rate (k'). The linear relationship between the swelling and fractions of drug release in Tris-HCl buffers was observed, indicating an important role of the swelling on controlling the drug release mechanism. Additionally, CSA of 200 and 800 kDa chitosan did not swell in pH 6.8 Tris-HCl but disintegrated into fractions, and the drug release from the matrix tablets was the highest. Copyright © 2010 Elsevier B.V. All rights reserved.

Strong adhesion and cohesion of chitosan in aqueous solutions

PubMed Central

Lee, Dong Woog; Lim, Chanoong; Israelachvili, Jacob N.; Hwang, Dong Soo

2014-01-01

Chitosan, a load-bearing biomacromolecule found in the exoskeletons of crustaceans and insects, is a promising biopolymer for the replacement of synthetic plastic compounds. Here, surface interactions mediated by chitosan in aqueous solutions, including the effects of pH and contact time, were investigated using a surface forces apparatus (SFA). Chitosan films showed an adhesion to mica for all tested pH ranges (3.0–8.5), achieving a maximum value at pH 3.0 after a contact time of 1 hr (Wad ~6.4 mJ/m2). We also found weak or no cohesion between two opposing chitosan layers on mica in aqueous buffer until the critical contact time for maximum adhesion (chitosan-mica) was reached. Strong cohesion (Wco ~8.5 mJ/m2) between the films was measured with increasing contact times up to 1 hr at pH 3.0, which is equivalent to ~60% of the strongest, previously reported, mussel underwater adhesion. Such time-dependent adhesion properties are most likely related to molecular or molecular group reorientations and interdigitations. At high pH (8.5), the solubility of chitosan changes drastically, causing the chitosan-chitosan (cohesion) interaction to be repulsive at all separation distances and contact times. The strong contact time and pH-dependent chitosan-chitosan cohesion and adhesion properties provide new insight into the development of chitosan based load-bearing materials. PMID:24138057

Humidity detection using chitosan film based sensor

NASA Astrophysics Data System (ADS)

Nasution, T. I.; Nainggolan, I.; Dalimunthe, D.; Balyan, M.; Cuana, R.; Khanifah, S.

2018-02-01

A humidity sensor made of the natural polymer chitosan has been successfully fabricated in the film form by a solution casting method. Humidity testing was performed by placing a chitosan film sensor in a cooling machine room, model KT-2000 Ahu. The testing results showed that the output voltage values of chitosan film sensor increased with the increase in humidity percentage. For the increase in humidity percentage from 30 to 90% showed that the output voltage of chitosan film sensor increased from 32.19 to 138.75 mV. It was also found that the sensor evidenced good repeatability and stability during the testing. Therefore, chitosan has a great potential to be used as new sensing material for the humidity detection of which was cheaper and environmentally friendly.

Preparation and modification of N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride nanoparticle as a protein carrier.

PubMed

Xu, Yongmei; Du, Yumin; Huang, Ronghua; Gao, Leping

2003-12-01

N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is water-soluble derivative of chitosan (CS), synthesized by the reaction between glycidyl-trimethyl-ammonium chloride and CS. HTCC nanoparticles have been formed based on ionic gelation process of HTCC and sodium tripolyphosphate (TPP). Bovine serum albumin (BSA), as a model protein drug, was incorporated into the HTCC nanoparticles. HTCC nanoparticles were 110-180 nm in size, and their encapsulation efficiency was up to 90%. In vitro release studies showed a burst effect and a slow and continuous release followed. Encapsulation efficiency was obviously increased with increase of initial BSA concentration. Increasing TPP concentration from 0.5 to 0.7 mg/ml promoted encapsulation efficiency from 46.7% to 90%, and delayed release. As for modified HTCC nanoparticles, adding polyethylene glycol (PEG) or sodium alginate obviously decreased the burst effect of BSA from 42% to 18%. Encapsulation efficiency was significantly reduced from 47.6% to 2% with increase of PEG from 1.0 to 20.0 mg/ml. Encapsulation efficiency was increased from 14.5% to 25.4% with increase of alginate from 0.3 to 1.0 mg/ml.

The effect of temperature and chitosan concentration during storage on the growth of chitosan nanoparticle produced by ionic gelation method

NASA Astrophysics Data System (ADS)

Handani, Wenny Rinda; Sediawan, Wahyudi Budi; Tawfiequrrahman, Ahmad; Wiratni, Kusumastuti, Yuni

2017-05-01

The objective of this research was to get the mechanism of nano size chitosan particle growth during storage by observing the effect of temperature and initial concentration of chitosan. The products were analyzed using PSA to have the average of particle radius. Nanochitosan solution was prepared by ionic gelation method. This method is described as an electrostatic interaction between positively charged amine with negatively charged polyanion, such as tripolyphosphate (TPP). Chitosan was dissolved in 1% acetic acid and was stirred for 30 minutes. Tween 80 was added to avoid agglomeration. TPP was prepared by dissolving 0.336 g into distilled water. The nano size chitosan was obtained by mixing TPP and chitosan solution dropwise while stirring for 30 minutes. This step was done at 15°C and ambient temperature (about 30°C) and chitosan concentration 0.2%, 0.4% and 0.6%. The results show that temperature during ionic gelation process (15°C and 30°C) does not affect the initial size of the nanoparticles produced as well as the growth of the nanoparticles during storage. On the other hand, initial chitosan concentration strongly affects initial size of the nanoparticles produced and the growth of the nanoparticles during storage. The concentration of chitosan at 0.2%, 0.4%, 0.6% gave initial size of nanoparticle chitosan of 175.3 nm, 337.9 nm, 643.3 nm respectively. On the other hand, the growth mechanism of chitosan nanoparticle depended on its radius(R). At R<500 nm, the growth rate of nanoparticles is controlled by adsorption at the surface of the particles, while at R>500 nm, it is controlled by diffusion in the liquid film around the particles.

Effects of sulfate chitosan derivatives on nonalcoholic fatty liver disease

NASA Astrophysics Data System (ADS)

Yu, Mingming; Wang, Yuanhong; Jiang, Tingfu; Lv, Zhihua

2014-06-01

Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentration emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly ameliorated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD.

[Development of a near-infrared fluorescence imaging system based on fluorescence properties of methylene blue].

PubMed

Huang, Lu-Mao; DU, Pei-Yan; Chen, Lan; Zhang, Sa; Zhou, Di-Fu; Chen, Chun-Lin; Xin, Xue-Gang

2018-04-20

To develop a near-infrared fluorescence imaging system based on the fluorescence properties of methylene blue. According to the optical properties of methylene blue, we used a custom-made specific LED light source and an interference filter, a CCD camera and other relevant components to construct the near-infrared fluorescence imaging system. We tested the signal-to-background ratio (SBR) of this imaging system for detecting methylene blue under different experimental conditions and analyzed the SBR in urine samples collected from 15 Wistar rats with intravenous injection of methylene blue at the doses of 0, 1.4, 1.6, 1.8, or 2.0 0 mg/kg methylene blue. The SBR of this imaging system for detecting methylene blue was affected by the concentration of methylene blue and the distance from the sample (P<0.05). In the urine samples from Wistar rats, the SBR varied with the the injection dose, and the rats injected with 1.6 mg/kg methylene blue showed the highest SBR (8.71∓0.20) in the urine (P<0.05). This near-infrared fluorescence imaging system is useful for fluorescence detection of methylene blue and can be used for real-time recognition of ureters during abdominal surgery.

77 FR 1512 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Methylene...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-10

... for OMB Review; Comment Request; Methylene Chloride Standard ACTION: Notice. SUMMARY: The Department... collection request (ICR) titled, ``Methylene Chloride Standard,'' to the Office of Management and Budget (OMB... at [email protected] . SUPPLEMENTARY INFORMATION: The methylene chloride (MC) standard requires...

Interaction between chitosan and its related enzymes: A review.

PubMed

Shinya, Shoko; Fukamizo, Tamo

2017-11-01

Chitosan-related enzymes including chitosanases, exo-β-glucosaminidases, and enzymes having chitosan-binding modules recognize ligands through electrostatic interactions between the acidic amino acids in proteins and amino groups of chitosan polysaccharides. However, in GH8 chitosanases, several aromatic residues are also involved in substrate recognition through stacking interactions, and these enzymes consequently hydrolyze β-1,4-glucan as well as chitosan. The binding grooves of these chitosanases are extended and opened at both ends of the grooves, so that the enzymes can clamp a long chitosan polysaccharide. The association/dissociation of positively charged glucosamine residues to/from the binding pocket of a GH2 exo-β-glucosaminidase controls the p K a of the catalytic acid, thereby maintaining the high catalytic potency of the enzyme. In contrast to chitosanases, chitosan-binding modules only accommodate a couple of glucosamine residues, predominantly recognizing the non-reducing end glucosamine residue of chitosan by electrostatic interactions and a hydrogen-bonding network. These structural findings on chitosan-related enzymes may contribute to future applications for the efficient conversion of the chitin/chitosan biomass. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrophoretic Deposition of Chitosan/h-BN and Chitosan/h-BN/TiO₂ Composite Coatings on Stainless Steel (316L) Substrates.

PubMed

Raddaha, Namir S; Cordero-Arias, Luis; Cabanas-Polo, Sandra; Virtanen, Sannakaisa; Roether, Judith A; Boccaccini, Aldo R

2014-03-04

This article presents the results of an experimental investigation designed to deposit chitosan/hexagonal boron nitride (h-BN) and chitosan/h-BN/titania (TiO₂) composites on SS316L substrates using electrophoretic deposition (EPD) for potential antibacterial applications. The influence of EPD parameters (voltage and deposition time) and relative concentrations of chitosan, h-BN and TiO₂ in suspension on deposition yield was studied. The composition and structure of deposited coatings were investigated by FTIR, XRD and SEM. It was observed that h-BN and TiO₂ particles were dispersed in the chitosan matrix through simultaneous deposition. The adhesion between the electrophoretic coatings and the stainless steel substrates was tested by using tape test technique, and the results showed that the adhesion strength corresponded to 3B and 4B classes. Corrosion resistance was evaluated by electrochemical polarization curves, indicating enhanced corrosion resistance of the chitosan/h-BN/TiO₂ and chitosan/h-BN coatings compared to the bare stainless steel substrate. In order to investigate the in-vitro inorganic bioactivity, coatings were immersed in simulated body fluid (SBF) for 28 days. FTIR and XRD results showed no formation of hydroxyapatite on the surface of chitosan/h-BN/TiO₂ and chitosan/h-BN coatings, which are therefore non bioactive but potentially useful as antibacterial coatings.

β-Chitin and chitosan from squid gladius: Biological activities of chitosan and its application as clarifying agent for apple juice.

PubMed

Abdelmalek, Baha Eddine; Sila, Assaâd; Haddar, Anissa; Bougatef, Ali; Ayadi, Mohamed Ali

2017-11-01

Chitin is the second most abundant polysaccharide in biomass after cellulose and the term chitosan usually refers to a family of polymers obtained after chitin deacetylation. The aim of this work was the preparation and the characterization of chitin and chitosan from the gladius (pen) of the European squid (Loligo vulgaris). A high level of deproteinization (more than 80%) was recorded using Alcalase ® with an enzyme/protein ratio of 10U/mg. The demineralization of the gladius was completely achieved within 8h at room temperature in HCl. 13 C NMR, FTIR, and XRD diffractograms of prepared chitin and chitosan were taken and then degree of deacetylation of chitosan was calculated using 13 C CP/MAS-NMR Spectroscopic. Further, in vitro antioxidant capacity of chitosan was evaluated on 1,1-diphenyl-2-picrylhydrazyl method (IC 50 =3.2mgmL -1 ) and the β-carotene bleaching assay (IC 50 =3.3mgmL -1 ). Antimicrobial activity was also investigated and assays indicated that prepared chitosan exhibited marked inhibitory activity against all microbial strains tested. Additionally, chitosan was tested such as clarifying agent for apple juice and showed powerful clarification capability, without affecting nutritional value. Furthermore, the results suggested that prepared chitosan could be used as alternative additive in pharmaceutical preparations and food industry. Copyright © 2017 Elsevier B.V. All rights reserved.

Poly(acrylonitrile)chitosan composite membranes for urease immobilization.

PubMed

Gabrovska, Katya; Georgieva, Aneliya; Godjevargova, Tzonka; Stoilova, Olya; Manolova, Nevena

2007-05-10

(Poly)acrylonitrile/chitosan (PANCHI) composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of PAN and PANCHI membranes were determined by TEM and SEM analyses. It was found that the average size of the pore under a selective layer base PAN membrane is 7 microm, while the membrane coated with 0.25% chitosan shows a reduced pore size--small or equal to 5 microm and with 0.35% chitosan--about 4 microm. The amounts of the functional groups, the degree of hydrophilicity and transport characteristics of PAN/Chitosan composite membranes were determined. Urease was covalently immobilized onto all kinds of PAN/chitosan composite membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity (94%) was measured for urease bound to PANCHI2 membranes (0.25% chitosan). The basic characteristics (pH(opt), pH(stability), T(opt), T(stability), heat inactivation and storage stability) of immobilized urease were determined. The obtained results show that the poly(acrylonitrile)chitosan composite membranes are suitable for enzyme immobilization.

Thermal decomposition reactions of cotton fabric treated with piperazine-phosphonates derivatives as a flame retardant

USDA-ARS?s Scientific Manuscript database

There has been a great scientific interest in exploring the great potential of the piperazine-phosphonates in flame retardant (FR) application on cotton fabric by investigating the thermal decomposition of cotton fabric treated with them. This research tries to understand the mode of action of the t...

Emerging Chitosan-Based Films for Food Packaging Applications.

PubMed

Wang, Hongxia; Qian, Jun; Ding, Fuyuan

2018-01-17

Recent years have witnessed great developments in biobased polymer packaging films for the serious environmental problems caused by the petroleum-based nonbiodegradable packaging materials. Chitosan is one of the most abundant biopolymers after cellulose. Chitosan-based materials have been widely applied in various fields for their biological and physical properties of biocompatibility, biodegradability, antimicrobial ability, and easy film forming ability. Different chitosan-based films have been fabricated and applied in the field of food packaging. Most of the review papers related to chitosan-based films are focusing on antibacterial food packaging films. Along with the advances in the nanotechnology and polymer science, numerous strategies, for instance direct casting, coating, dipping, layer-by-layer assembly, and extrusion, have been employed to prepare chitosan-based films with multiple functionalities. The emerging food packaging applications of chitosan-based films as antibacterial films, barrier films, and sensing films have achieved great developments. This article comprehensively reviews recent advances in the preparation and application of engineered chitosan-based films in food packaging fields.

Lecithin/chitosan nanoparticles for transdermal delivery of melatonin.

PubMed

Hafner, Anita; Lovrić, Jasmina; Pepić, Ivan; Filipović-Grčić, Jelena

2011-01-01

In this study, the potential of lecithin/chitosan nanoparticles (NPs) as colloidal nanosystem for transdermal melatonin delivery was investigated. Mean diameter and zeta-potential of NPs differing in lecithin type (Lipoid S45 and S100) and chitosan content ranged between 113.7 and 331.5 nm and 4.6 and 31.2 mV, respectively. Melatonin loadings were up to 7.2%. The potential of lecithin/chitosan NPs to enhance transdermal melatonin delivery was investigated by determining the drug flux across dermatomed porcine skin and its skin deposition. Lecithin/chitosan NPs provided 1.3-2.3-fold higher flux compared to melatonin solution. The highest flux, 9.0 ± 0.21 µg/cm²/h, was observed for S45 lecithin/chitosan NPs with lecithin/chitosan weight ratio of 20:1. NP possible cytotoxicity in vitro was evaluated using human skin keratinocytes and fibroblasts. It was demonstrated that lecithin/chitosan NPs can be applied to skin cells at concentrations up to 200 µg/mL without inducing plasma membrane damage or cell viability decrease.

A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material.

PubMed

Wen, Zhaohui; Zhang, Liming; Chen, Chao; Liu, Yibo; Wu, Changjun; Dai, Changsong

2013-04-01

Slow corrosion rate and poor bioactivity restrict iron-based implants in biomedical application. In this study, we design a new iron-foam-based calcium phosphate/chitosan coating biodegradable composites offering a priority mechanical and bioactive property for bone tissue engineering through electrophoretic deposition (EPD) followed by a conversion process into a phosphate buffer solution (PBS). Tensile test results showed that the mechanical property of iron foam could be regulated through altering the construction of polyurethane foam. The priority coatings were deposited from 40% nano hydroxyapatite (nHA)/ethanol suspension mixed with 60% nHA/chitosan-acetic acid aqueous solution. In vitro immersion test showed that oxidation-iron foam as the matrix decreased the amount of iron implanted and had not influence on the bioactivity of this implant, obviously. So, this method could also be a promising method for the preparation of a new calcium phosphate/chitosan coating on foam construction. Copyright © 2012. Published by Elsevier B.V.

High-efficiency volume holograms recording on acrylamide and N,N‧methylene-bis-acrylamide photopolymer with pulsed laser

NASA Astrophysics Data System (ADS)

Gallego, S.; Ortuño, M.; García, C.; Neipp, C.; Beléndez, A.; Pascual, I.

2005-11-01

In order to achieve a better understanding of the mechanisms of hologram formation and higher diffraction efficiencies in volume gratings stored in acrylamide based photopolymers, a crosslinker (N,N'methylene-bis-acrylamide) has been incorporated in the photopolymer to record holograms by pulsed laser exposure. The presence of this component increases the polymerization rate and refractive index modulation. The recording was performed using a holographic copying process. The original was a grating of 1000?lines/mm processed using silver halide sensitized gelatin. First, the effect of the pulse fluence was investigated. When the pulse fluence was optimized, the results obtained using the new composition of material were compared with those using the composition without a crosslinker. Using a pulsed laser at 532?nm the photopolymer without crosslinker presented diffraction efficiencies slightly less than 60%. On the other hand, when the crosslinker was introduced in the photopolymer composition, the diffraction efficiencies achieved were higher than 85%. The non-linearity of the material's response was also studied comparing the energetic sensitivity, diffraction efficiencies and index modulation of gratings recorded with pulsed and continuous laser exposure. This study was performed fitting the angular scan of each grating using Kogelnik's theory.

Effect of polymer molecular weight on chitosan-protein interaction.

PubMed

Bekale, L; Agudelo, D; Tajmir-Riahi, H A

2015-01-01

We present a comprehensive study of the interactions between chitosan nanoparticles (15, 100 and 200 kDa with the same degree of deacetylation 90%) and two model proteins, i.e., bovine (BSA) and human serum albumins (HSA), with the aim of correlating chitosan molecular weight (Mw) and the binding affinity of these naturally occurring polymers to protein. The effect of chitosan on the protein secondary structure and the influence of protein complexation on the shape of chitosan nanoparticles are discussed. A combination of multiple spectroscopic methods, transmission electron microscopy (TEM) and thermodynamic analysis were used to assess the polymer-protein complex formation. Results revealed that the three chitosan nanoparticles interact with BSA to form chitosan-BSA complexes, mainly through hydrophobic contacts with the affinity order: 200>100>15 kDa. However, HSA-chitosan complexation is mainly via electrostatic interactions with the stability order: 100>200>15 kDa. Furthermore, the association between polymer and protein causes a partial protein conformational change by a major reduction of α-helix from 63% (free BSA) to 57% (chitosan-BSA) and 57% (free HSA) to 51% (chitosan-HSA). Finally, TEM micrographs clearly revealed that the binding of serum albumins with chitosan nanoparticles induces a significant change in protein morphology and the shape of the polymer. Copyright © 2014 Elsevier B.V. All rights reserved.

N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride: An immune-enhancing adjuvant for hepatitis E virus recombinant polypeptide vaccine in mice.

PubMed

Tao, Wei; Zheng, Hai-Qun; Fu, Ting; He, Zhuo-Jing; Hong, Yan

2017-08-03

Adjuvants are essential for enhancing vaccine potency by improving the humoral and/or cell-mediated immune response to vaccine antigens. This study was performed to evaluate the immuno-enhancing characteristic of N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (HTCC), the cationically modified chitosan, as an adjuvant for hepatitis E virus (HEV) recombinant polypeptide vaccine. Animal experiments showed that HTCC provides adjuvant activity when co-administered with HEV recombinant polypeptide vaccine by intramuscularly route. Vaccination using HTCC as an adjuvant was associated with increases of the serum HEV-specific IgG antibodies, splenocytes proliferation and the growths of CD4 + CD8 - T lymphocytes and IFN-γ-secreting T lymphocytes in peripheral blood. These findings suggested that HTCC had strong immuno-enhancing effect. Our findings are the first to demonstrate that HTCC is safe and effective in inducing a good antibody response and stimulating Th1-biased immune responses for HEV recombinant polypeptide vaccine.

Synthesis of α,α-Difluorinated Phosphonate pSer/pThr Mimetics via Rhodium-Catalyzed Asymmetric Hydrogenation of β-Difluorophosphonomethyl α-(Acylamino)acrylates.

PubMed

Chen, Hong-Xue; Kang, Jie; Chang, Rong; Zhang, Yun-Lai; Duan, Hua-Zhen; Li, Yan-Mei; Chen, Yong-Xiang

2018-06-01

A novel and facile synthetic strategy for α,α-difluorinated phosphonate mimetics of phosphoserine/phosphothreonine utilizing rhodium-catalyzed asymmetric hydrogenation was developed. The dehydrogenated substrate β-difluorophosphonomethyl α-(acylamino)acrylates were first prepared from protected serine/threonine followed by asymmetric hydrogenation using the rhodium-DuPhos catalytic system to generate the chiral center(s). These important phosphonate building blocks were successfully incorporated into phosphatase-resistant peptides, which displayed similar inhibition to the 14-3-3 ζ protein as the parent pSer/pThr peptides.

Study on different molecular weights of chitosan as an immobilization matrix for a glucose biosensor.

PubMed

Ang, Lee Fung; Por, Lip Yee; Yam, Mun Fei

2013-01-01

Two chitosan samples (medium molecular weight (MMCHI) and low molecular weight (LMCHI)) were investigated as an enzyme immobilization matrix for the fabrication of a glucose biosensor. Chitosan membranes prepared from acetic acid were flexible, transparent, smooth and quick-drying. The FTIR spectra showed the existence of intermolecular interactions between chitosan and glucose oxidase (GOD). Higher catalytic activities were observed on for GOD-MMCHI than GOD-LMCHI and for those crosslinked with glutaraldehyde than using the adsorption technique. Enzyme loading greater than 0.6 mg decreased the activity. Under optimum conditions (pH 6.0, 35°C and applied potential of 0.6 V) response times of 85 s and 65 s were observed for medium molecular weight chitosan glucose biosensor (GOD-MMCHI/PT) and low molecular weight chitosan glucose biosensor (GOD-LMCHI/PT), respectively. The apparent Michaelis-Menten constant ([Formula: see text]) was found to be 12.737 mM for GOD-MMCHI/PT and 17.692 mM for GOD-LMCHI/PT. This indicated that GOD-MMCHI/PT had greater affinity for the enzyme. Moreover, GOD-MMCHI/PT showed higher sensitivity (52.3666 nA/mM glucose) when compared with GOD-LMCHI/PT (9.8579 nA/mM glucose) at S/N>3. Better repeatability and reproducibility were achieved with GOD-MMCHI/PT than GOD-LMCHI/PT regarding glucose measurement. GOD-MMCHI/PT was found to give the highest enzymatic activity among the electrodes under investigation. The extent of interference encountered by GOD-MMCHI/PT and GOD-LMCHI/PT was not significantly different. Although the Nafion coated biosensor significantly reduced the signal due to the interferents under study, it also significantly reduced the response to glucose. The performance of the biosensors in the determination of glucose in rat serum was evaluated. Comparatively better accuracy and recovery results were obtained for GOD-MMCHI/PT. Hence, GOD-MMCHI/PT showed a better performance when compared with GOD-LMCHI/PT. In conclusion

Study on Different Molecular Weights of Chitosan as an Immobilization Matrix for a Glucose Biosensor

PubMed Central

Ang, Lee Fung; Por, Lip Yee; Yam, Mun Fei

2013-01-01

Two chitosan samples (medium molecular weight (MMCHI) and low molecular weight (LMCHI)) were investigated as an enzyme immobilization matrix for the fabrication of a glucose biosensor. Chitosan membranes prepared from acetic acid were flexible, transparent, smooth and quick-drying. The FTIR spectra showed the existence of intermolecular interactions between chitosan and glucose oxidase (GOD). Higher catalytic activities were observed on for GOD-MMCHI than GOD-LMCHI and for those crosslinked with glutaraldehyde than using the adsorption technique. Enzyme loading greater than 0.6 mg decreased the activity. Under optimum conditions (pH 6.0, 35°C and applied potential of 0.6 V) response times of 85 s and 65 s were observed for medium molecular weight chitosan glucose biosensor (GOD-MMCHI/PT) and low molecular weight chitosan glucose biosensor (GOD-LMCHI/PT), respectively. The apparent Michaelis-Menten constant () was found to be 12.737 mM for GOD-MMCHI/PT and 17.692 mM for GOD-LMCHI/PT. This indicated that GOD-MMCHI/PT had greater affinity for the enzyme. Moreover, GOD-MMCHI/PT showed higher sensitivity (52.3666 nA/mM glucose) when compared with GOD-LMCHI/PT (9.8579 nA/mM glucose) at S/N>3. Better repeatability and reproducibility were achieved with GOD-MMCHI/PT than GOD-LMCHI/PT regarding glucose measurement. GOD-MMCHI/PT was found to give the highest enzymatic activity among the electrodes under investigation. The extent of interference encountered by GOD-MMCHI/PT and GOD-LMCHI/PT was not significantly different. Although the Nafion coated biosensor significantly reduced the signal due to the interferents under study, it also significantly reduced the response to glucose. The performance of the biosensors in the determination of glucose in rat serum was evaluated. Comparatively better accuracy and recovery results were obtained for GOD-MMCHI/PT. Hence, GOD-MMCHI/PT showed a better performance when compared with GOD-LMCHI/PT. In conclusion, chitosan membranes shave

Effect of degree of deacetylation of chitosan on adsorption capacity and reusability of chitosan/polyvinyl alcohol/TiO2 nano composite.

PubMed

Habiba, Umma; Joo, Tan Chin; Siddique, Tawsif A; Salleh, Areisman; Ang, Bee Chin; Afifi, Amalina M

2017-11-01

The chitosan/polyvinyl alcohol/TiO 2 composite was synthesized. Two different degrees of deacetylation of chitosan were prepared by hydrolysis to compare the effectiveness of them. The composite was analyzed via field emission scanning electron microscopy, Fourier transform infrared, X-ray diffraction, thermal gravimetric analysis, weight loss test and adsorption study. The FTIR and XRD results proved the interaction among chitosan, PVA and TiO 2 without any chemical reaction. It was found that, chitosan with higher degree of deacetylation has better stability. Furthermore, it also showed that higher DD of chitosan required less time to reach equilibrium for methyl orange. The adsorption followed the pseudo-second-order kinetic model. The Langmuir and Freundlich isotherm models were fitted well for isotherm study. Adsorption capacity was higher for the composite containing chitosan with higher DD. The dye removal rate was independent of the dye's initial concentration. The adsorption capacity was increased with temperature and it was found from reusability test that the composite containing chitosan with higher DD is more reusable. It was notable that adsorption capacity was even after 15 runs. Therefore, chitosan/PVA/TiO 2 composite can be a very useful material for dye removal. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and characterisation of zein and chitosan edible film

USDA-ARS?s Scientific Manuscript database

The aim of this work was to develop zein/chitosan blends and study the heat effect on chitosan in the film-making process. The zein and chitosan solutions were prepared separately; two different chitosan solutions were produced, one heated at 80 ºC for 1 h, and another just stirred for 1 h and unhea...

Barrier properties of nano silicon carbide designed chitosan nanocomposites.

PubMed

Pradhan, Gopal C; Dash, Satyabrata; Swain, Sarat K

2015-12-10

Nano silicon carbide (SiC) designed chitosan nanocomposites were prepared by solution technique. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used for studying structural interaction of nano silicon carbide (SiC) with chitosan. The morphology of chitosan/SiC nanocomposites was investigated by field emission scanning electron microscope (FESEM), and high resolution transmission electron microscope (HRTEM). The thermal stability of chitosan was substantially increased due to incorporation of stable silicon carbide nanopowder. The oxygen permeability of chitosan/SiC nanocomposites was reduced by three folds as compared to the virgin chitosan. The chemical resistance properties of chitosan were enhanced due to the incorporation of nano SiC. The biodegradability was investigated using sludge water. The tensile strength of chitosan/SiC nanocomposites was increased with increasing percentage of SiC. The substantial reduction in oxygen barrier properties in combination with increased thermal stability, tensile strength and chemical resistance properties; the synthesized nanocomposite may be suitable for packaging applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Scanning electron microscopy (SEM) evaluation of sealing ability of MTA and EndoSequence as root-end filling materials with chitosan and carboxymethyl chitosan (CMC) as retrograde smear layer removing agents.

PubMed

Nagesh, Bolla; Jeevani, Eppala; Sujana, Varri; Damaraju, Bharagavi; Sreeha, Kaluvakolanu; Ramesh, Penumaka

2016-01-01

The purpose of this study was to evaluate the sealing ability of mineral trioxide aggregate (MTA) and EndoSequence with chitosan and carboxymethyl chitosan (CMC) as retrograde smear layer removing agents using scanning electron microscopy (SEM). Forty human single rooted teeth were taken. Crowns were decoronated and canals were obturated. Apically roots were resected and retrograde cavities were done. Based on the type of retrograde material placed and the type of smear layer removal agent used for retrograde cavities, they were divided into four groups (N = 10): Group I chitosan with EndoSequence, group II chitosan with MTA, group III CMC with EndoSequence, and Group IV CMC with MTA. All the samples were longitudinally sectioned, and the SEM analysis was done for marginal adaptation. Kruskal-Wallis and Mann-Witney analysis tests. SEM images showed the presence of less gaps in group III, i.e., CMC with EndoSequence when compared to other groups with statistically significant difference. Within the limited scope of this study, it was concluded that EndoSequence as retrograde material showed better marginal sealing ability.

Synthesis and characteristics of chitin and chitosan with the (2-hydroxy-3-trimethylammonium)propyl functionality, and evaluation of their antioxidant activity in vitro.

PubMed

Zhang, Xiao; Geng, Xiaodong; Jiang, Hengjun; Li, Jianrong; Huang, Jianying

2012-06-20

Quaternary amino groups were introduced into chitin and chitosan to obtain O-(2-hydroxy-3-trimethylammonium)propyl chitin (OHT-chitin) and N-(2-hydroxy-3-trimethylammonium)propyl chitosan (NHT-chitosan). They were characterized by FTIR spectra, and GPC. The molecular weight Mw of OHT-chitin and NHT-chitosan were 8986 and 9723 with polydispersity of 1.01 and 1.0 2, respectively. Their antioxidant activities in vitro were further studied. It was found that β-carotene-linoleic acid values of OHT-chitin and NHT-chitosan at 0.8 mg/mL were up to 91% and 96%, while that of chitosan was 40%. Based on photobleaching of α,α-diphenyl-β-picrylhydrazyl (DPPH) at 326 nm, the DPPH inhibitory activity of OHT-chitin and NHT-chitosan was 30.9% and 31.9% at 5 mg/mL, whereas chitosan only gave 4.8%. It was also exhibited that OHT-chitin and NHT-chitosan had better antioxidant activity than chitosan according to the reducing power as well as H2O2 scavenging activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

An unusual methylene aziridine refined in P2(1)/c and the nonstandard setting P2(1)/n.

PubMed

Feast, George C; Haestier, James; Page, Lee W; Robertson, Jeremy; Thompson, Amber L; Watkin, David J

2009-12-01

The unusual methylene aziridine 6-tert-butyl-3-oxa-2-thia-1-azabicyclo[5.1.0]oct-6-ene 2,2-dioxide, C(9)H(15)NO(3)S, was found to crystallize with two molecules in the asymmetric unit. The structure was solved in both the approximately orthogonal and the oblique settings of space group No. 14, viz. P2(1)/n and P2(1)/c, respectively. A comparison of these results clearly displayed an increase in the correlation between coordinates in the ac plane for the oblique cell. The increase in the corresponding covariances makes a significant contribution to the standard uncertainties of derived parameters, e.g. bond lengths. Since there is yet no CIF definition for the full variance-covariance matrix, there are clear advantages to reporting the structure in the nonstandard space-group setting.

Functional Comparison for Lipid Metabolism and Intestinal and Fecal Microflora Enzyme Activities between Low Molecular Weight Chitosan and Chitosan Oligosaccharide in High-Fat-Diet-Fed Rats.

PubMed

Chiu, Chen-Yuan; Feng, Shih-An; Liu, Shing-Hwa; Chiang, Meng-Tsan

2017-07-24

The present study investigated and compared the regulatory effects on the lipid-related metabolism and intestinal disaccharidase/fecal bacterial enzyme activities between low molecular weight chitosan and chitosan oligosaccharide in high-fat-diet-fed rats. Diet supplementation of low molecular weight chitosan showed greater efficiency than chitosan oligosaccharide in suppressing the increased weights in body and in liver and adipose tissues of high-fat-diet-fed rats. Supplementation of low molecular weight chitosan also showed a greater improvement than chitosan oligosaccharide in imbalance of plasma, hepatic, and fecal lipid profiles, and intestinal disaccharidase activities in high-fat-diet-fed rats. Moreover, both low molecular weight chitosan and chitosan oligosaccharide significantly decreased the fecal microflora mucinase and β-glucuronidase activities in high-fat-diet-fed rats. These results suggest that low molecular weight chitosan exerts a greater positive improvement than chitosan oligosaccharide in lipid metabolism and intestinal disaccharidase activity in high-fat-diet-induced obese rats.

Validation of an ergonomic method to withdraw [99mTc] radiopharmaceuticals.

PubMed

Blondeel-Gomes, Sandy; Marie, Solène; Fouque, Julien; Loyeau, Sabrina; Madar, Olivier; Lokiec, François

2017-11-10

The main objective of the present work was to ensure quality of radiopharmaceuticals syringes withdrawn with a "Spinal needle/obturator In-Stopper" system. Methods: Visual examinations and physicochemical tests are performed at T0 and T+4h for [ 99m Tc]albumin nanocolloid and T+7h for [ 99m Tc]eluate, [ 99m Tc] HydroxyMethylene DiPhosphonate and [ 99m Tc]Human Serum Albumin. Microbiological validation was performed according to European pharmacopoeia. Fingertip radiation exposure was evaluated to confirm the safety of the system. Results: Results show stable visual and physicochemical properties. The integrity of the connector was not affected after 30 punctures (no cores). No microbiological contamination was found on tested syringes. Conclusion: The system could be used 30 times. The stability of syringes drawing with this method is guaranteed up to 4 hours for [ 99m Tc]albumin nanocolloid and 7 hours for [ 99m Tc]eluate, [ 99m Tc]HydroxyMethylene DisPhosphonate and [ 99m Tc]Human serum albumin. Copyright © 2017 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Thiolated chitosans: useful excipients for oral drug delivery.

PubMed

Werle, Martin; Bernkop-Schnürch, Andreas

2008-03-01

To improve the bioavailability of orally administered drugs, formulations based on polymers are of great interest for pharmaceutical technologists. Thiolated chitosans are multifunctional polymers that exhibit improved mucoadhesive, cohesive and permeation-enhancing as well as efflux-pump-inhibitory properties. They can be synthesized by derivatization of the primary amino groups of chitosan with coupling reagents bearing thiol functions. Various data gained in-vitro as well as in-vivo studies clearly demonstrate the potential of thiolated chitosans for oral drug delivery. Within the current review, the synthesis and characterization of thiolated chitosans so far developed is summarized. Features of thiolated chitosans important for oral drug delivery are discussed as well. Moreover, different formulation approaches, such as matrix tablets and micro-/nanoparticles, as well as the applicability of thiolated chitosans for the oral delivery of various substance classes including peptides and efflux pump substrates, are highlighted.

Chitosan-caseinate bilayer coatings for paper packaging materials.

PubMed

Khwaldia, Khaoula; Basta, Altaf H; Aloui, Hajer; El-Saied, Houssni

2014-01-01

Papers coated with caseinate and caseinate/chitosan bilayer films were developed. Caseinate, chitosan and caseinate/chitosan films were preliminary characterized by FTIR spectroscopy and thermal stability analyses. The effects of coating weight, caseinate concentration (7%, 10%, and 12%, w/w), and coating application methods (single layer and bilayer) on the physical and mechanical properties of coated papers were studied. Increasing the concentration of caseinate led to a decrease in water vapor permeability (WVP) of the resulting coated paper sheets. Chitosan significantly (p<0.05) increased the elongation at break (%E) of coated paper. However, the application of chitosan as a second layer on wet or dry caseinate films did not significantly affect (p>0.05) the tensile strength (TS) of coated paper. The greatest reduction in paper WVP is achieved by addition of a chitosan layer to the dried preformed caseinate-coated paper. Copyright © 2013 Elsevier Ltd. All rights reserved.

Photocatalytic enhancement of floating photocatalyst: Layer-by-layer hybrid carbonized chitosan and Fe-N- codoped TiO2 on fly ash cenospheres

NASA Astrophysics Data System (ADS)

Song, Jingke; Wang, Xuejiang; Bu, Yunjie; Wang, Xin; Zhang, Jing; Huang, Jiayu; Ma, RongRong; Zhao, Jianfu

2017-01-01

Due to the advantage of floating on water surface, floating photocatalysts show higher rates of radical formation and collection efficiencies. And they were expected to be used for solar remediation of non-stirred and non-oxygenated reservoirs. In this research, floating fly ash cenospheres (FAC) supported layer-by- layer hybrid carbonized chitosan and Fe-N-codoped TiO2 was prepared by a simple sol-gel method. The catalysts were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy(DRS), nitrogen adsorption analyses for Brunauer-Emmett-Teller (BET) specific surface area. It is indicated that Fe-N codoped narrowed the material's band gap, and the layer of carbonized chitosan (Cts) increased the catalyst's adsorption capacity and the absorption ability of visible light. Comparing with Fe-N-TiO2/FAC and N-TiO2/FAC, the composite photocatalyst show excellent performance on the degradation of RhB. Photodegradation rate of RhB by Fe-N-TiO2/FAC-Cts was 0.01018 min-1, which is about 1.5 and 2.09 times higher than Fe-N-TiO2/FAC and N-TiO2/FAC under visible light irradiation in 240 min, respectively. The dye photosentization, capture of holes and electrons by Fe3+ ion, and synergistic effect of adsorption and photodegradation were attributed to the results for the improvement of photocatalytic performance. The floating photocatalyst can be reused for at least three consecutive times without any significant decrease on the degradation of Rhodamin B after each reuse.

Spectrum and mechanisms of inflammasome activation by chitosan.

PubMed

Bueter, Chelsea L; Lee, Chrono K; Wang, Jennifer P; Ostroff, Gary R; Specht, Charles A; Levitz, Stuart M

2014-06-15

Chitosan, the deacetylated derivative of chitin, can be found in the cell wall of some fungi and is used in translational applications. We have shown that highly purified preparations of chitosan, but not chitin, activate the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in primed mouse bone marrow-derived macrophages (BMMΦ), inducing a robust IL-1β response. In this article, we further define specific cell types that are activated and delineate mechanisms of activation. BMMΦ differentiated to promote a classically activated (M1) phenotype released more IL-1β in response to chitosan than intermediate or alternatively activated macrophages (M2). Chitosan, but not chitin, induced a robust IL-1β response in mouse dendritic cells, peritoneal macrophages, and human PBMCs. Three mechanisms for NLRP3 inflammasome activation may contribute: K(+) efflux, reactive oxygen species, and lysosomal destabilization. The contributions of these mechanisms were tested using a K(+) efflux inhibitor, high extracellular potassium, a mitochondrial reactive oxygen species inhibitor, lysosomal acidification inhibitors, and a cathepsin B inhibitor. These studies revealed that each of these pathways participated in optimal NLRP3 inflammasome activation by chitosan. Finally, neither chitosan nor chitin stimulated significant release from unprimed BMMΦ of any of 22 cytokines and chemokines assayed. This study has the following conclusions: 1) chitosan, but not chitin, stimulates IL-1β release from multiple murine and human cell types; 2) multiple nonredundant mechanisms appear to participate in inflammasome activation by chitosan; and 3) chitin and chitosan are relatively weak stimulators of inflammatory mediators from unprimed BMMΦ. These data have implications for understanding the nature of the immune response to microbes and biomaterials that contain chitin and chitosan. Copyright © 2014 by The American Association of Immunologists, Inc.

64Cu-Labeled Phosphonate Cross-Bridged Chelator Conjugates of c(RGDyK) for PET/CT Imaging of Osteolytic Bone Metastases.

PubMed

Ocak, Meltem; Beaino, Wissam; White, Alexander; Zeng, Dexing; Cai, Zhengxin; Anderson, Carolyn J

2018-03-01

The goal of this research was to evaluate c(RGDyK) conjugated to phosphonate-based cross-bridged chelators using Cu-free click chemistry in the 4T1 mouse mammary tumor bone metastasis model in comparison with 64 Cu-CB-TE2A-c(RGDyK), which previously showed selective binding to integrin αvβ3 on osteoclasts. Two phosphonate-based cross-bridged chelators (CB-TE1A1P and CB-TE1K1P) were conjugated to c(RGDyK) through bio-orthogonal strain-promoted alkyne-azide cycloaddition. In vitro and in vivo evaluation of the 64 Cu-labeled TE1A1P-DBCO-c(RGDyK) (AP-c(RGDyK)), TE1K1P-PEG4-DBCO-c(RGDyK) (KP-c(RGDyK)), and CB-TE2A-c(RGDyK) were compared in the 4T1 mouse model of bone metastasis. The affinities of the unconjugated and chelator-c(RGDyK) analogs for αvβ3 integrin were determined using a competitive-binding assay. For in vivo evaluation, BALB/c mice were injected with 1 × 10 5 4T1/Luc cells in the left ventricle. Formation of metastases was monitored by bioluminescence imaging (BLI) followed by small-animal PET/CT 2 h postinjection of radiotracers. The chelator-peptide conjugates showed similar affinity to integrin αvβ3, in the low nM range. PET imaging demonstrated a higher uptake in bones having metastases for all 64 Cu-labeled c(RGDyK) analogs compared with bones in nontumor-bearing mice. The correlation between uptake of 64 Cu-AP-c(RGDyK) and 64 Cu-KP-c(RGDyK) in bones with metastases based on PET/CT imaging, and osteoclast number based on histomorphometry, was improved over the previously investigated 64 Cu-CB-TE2A-c(RGDyK). These data suggest that the phosphonate chelator conjugates of c(RDGyK) peptides are promising PET tracers suitable for imaging tumor-associated osteoclasts in bone metastases.

Rapidly photo-cross-linkable chitosan hydrogel for peripheral neurosurgeries.

PubMed

Rickett, Todd A; Amoozgar, Zohreh; Tuchek, Chad A; Park, Joonyoung; Yeo, Yoon; Shi, Riyi

2011-01-10

Restoring continuity to severed peripheral nerves is crucial to regeneration and enables functional recovery. However, the two most common agents for coaptation, sutures and fibrin glues, have drawbacks such as inflammation, pathogenesis, and dehiscence. Chitosan-based adhesives are a promising alternative, reported to have good cytocompatibility and favorable immunogenicity. A photo-cross-linkable hydrogel based on chitosan is proposed as a new adhesive for peripheral nerve anastomosis. Two Az-chitosans were synthesized by conjugating 4-azidobenzoic acid with low (LMW, 15 kDa) and high (HMW, 50-190 kDa) molecular weight chitosans. These solutions formed a hydrogel in less than 1 min under UV light. The LMW Az-chitosan was more tightly cross-linked than the HMW variant, undergoing significantly less swelling and possessing a higher rheological storage modulus, and both Az-chitosan gels were stiffer than commercial fibrin glue. Severed nerves repaired by Az-chitosan adhesives tolerated longitudinal forces comparable or superior to fibrin glue. Adhesive exposure to intact nerves and neural cell culture showed both Az-chitosans to be nontoxic in the acute (minutes) and chronic (days) time frames. These results demonstrate that Az-chitosan hydrogels are cytocompatible and mechanically suitable for use as bioadhesives in peripheral neurosurgeries.

Poly(D,L-Lactide-Co-Glycolide) Tubes With Multifilament Chitosan Yarn or Chitosan Sponge Core in Nerve Regeneration.

PubMed

Wlaszczuk, Adam; Marcol, Wiesław; Kucharska, Magdalena; Wawro, Dariusz; Palen, Piotr; Lewin-Kowalik, Joanna

2016-11-01

The influence of different kinds of nerve guidance conduits on regeneration of totally transected rat sciatic nerves through a 7-mm gap was examined. Five different types of conduits made of chitosan and poly(D,L-lactide-co-glycolide) (PLGA) were constructed and tested in vivo. We divided 50 animals into equal groups of 10, with a different type of conduit implanted in each group: chitosan sponge core with an average molecular mass of polymer (Mv) of 287 kDa with 7 channels in a PLGA sleeve, chitosan sponge core with an Mv of 423 kDa with 7 channels in a PLGA sleeve, chitosan sponge core (Mv, 423 kDa) with 13 channels in a PLGA sleeve, chitosan multifilament yarn in a PLGA sleeve, and a PLGA sleeve only. Seven weeks after the operation, we examined the distance covered by regenerating nerve fibers, growing of nerves into the conduit's core, and intensity and type of inflammatory reaction in the conduit, as well as autotomy behavior (reflecting neuropathic pain intensity) in the animals. Two types of conduits were allowing nerve outgrowth through the gap with minor autotomy and minor inflammatory reactions. These were the conduits with chitosan multifilament yarn in a PLGA sleeve and the conduits with 13-channel microcrystalline chitosan sponge in a PLGA sleeve. The type of chitosan used to build the nerve guidance conduit influences the intensity and character of inflammatory reaction present during nerve regeneration, which in turn affects the distance crossed by regenerating nerve fibers, growing of the nerve fibers into the conduit's core, and the intensity of autotomy in the animals. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Synthesis, characterization and antibacterial activity of hybrid chitosan-cerium oxide nanoparticles: As a bionanomaterials.

PubMed

Senthilkumar, R P; Bhuvaneshwari, V; Ranjithkumar, R; Sathiyavimal, S; Malayaman, V; Chandarshekar, B

2017-11-01

The hybrid chitosan cerium oxide nanoparticles were prepared for the first time by green chemistry approach using plant leaf extract. The intense peak observed around 292nm in the UV-vis spectrum indicate the formation of cerium oxide nanoparticles. The XRD pattern revealed that the hybrid chitosan-cerium oxide nanoparticles have a polycrystalline structure with cubic fluorite phase. The FTIR spectrum of prepared samples showed the formation of Ce-O bonds and chitosan main chains COC and CO. The FESEM image of hybrid chitosan cerium oxide nanoparticles revealed that the particles are spherical in shape with grains size varying from 23.12nm to 89.91nm. EDAX analysis confirmed the presence of Ce, O, C and N elements in the prepared sample. TEM images showed that the prepared hybrid chitosan-cerium oxide nanoparticles are predominantly uniform in size and most of the particles are spherical in shape with less agglomeration and the particles size varies from 3.61nm to 24.40nm. The prepared chitosan cerium oxide nanoparticles of 50μL concentration showed good antibacterial properties against test pathogens, which was confirmed by the FESEM analysis. The prepared small particle size facilitate that these hybrid ChiCO 2 NPs could effectively be used in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Plant Growth Hormones on Mucor indicus Growth and Chitosan and Ethanol Production.

PubMed

Safaei, Zahra; Karimi, Keikhosro; Golkar, Poorandokht; Zamani, Akram

2015-07-22

The objective of this study was to investigate the effects of indole-3-acetic acid (IAA) and kinetin (KIN) on Mucor indicus growth, cell wall composition, and ethanol production. A semi-synthetic medium, supplemented with 0-5 mg/L hormones, was used for the cultivations (at 32 °C for 48 h). By addition of 1 mg/L of each hormone, the biomass and ethanol yields were increased and decreased, respectively. At higher levels, however, an inverse trend was observed. The glucosamine fraction of the cell wall, as a representative for chitosan, followed similar but sharper changes, compared to the biomass. The highest level was 221% higher than that obtained without hormones. The sum of glucosamine and N-acetyl glucosamine (chitin and chitosan) was noticeably enhanced in the presence of the hormones. Increase of chitosan was accompanied by a decrease in the phosphate content, with the lowest phosphate (0.01 g/g cell wall) being obtained when the chitosan was at the maximum (0.45 g/g cell wall). In conclusion, IAA and KIN significantly enhanced the M. indicus growth and chitosan production, while at the same time decreasing the ethanol yield to some extent. This study shows that plant growth hormones have a high potential for the improvement of fungal chitosan production by M. indicus.

Chitosan derivatives with antimicrobial, antitumour and antioxidant activities--a review.

PubMed

Jarmila, Vinsová; Vavríková, Eva

2011-01-01

Chitosan is a linear polysaccharide with a good biodegradability, biocompatibility, and no toxicity, which provide it with huge potential for future development. The chitosan molecule appears to be a suitable polymeric complex for many biomedical applications. This review gathers current findings on the antibacterial, antifungal, antitumour and antioxidant activities of chitosan derivatives and concurs with our previous review presenting data collected up to 2008. Antibacterial activity is based on molecular weight, the degree of deacetylation, the type of substitutents, which can be cationic or easily form cations, and the type of bacterium. In general, high molecular weight chitosan cannot pass through cell membranes and forms a film that protects cells against nutrient transport through the microbial cell membrane. Low molecular weight chitosan derivatives are water soluble and can better incorporate the active molecule into the cell. Gram-negative bacteria, often represented by Escherichia coli, have an anionic bacterial surface on which cationic chitosan derivatives interact electrostatically. Thus, many chitosan conjugates have cationic components such as ammonium, pyridinium or piperazinium substituents introduced into their molecules to increase their positive charge. Gram-positive bacteria like Staphylococcus aureus are inhibited by the binding of lower molecular weight chitosan derivatives to DNA or RNA. Chitosan nanoparticles exhibit an increase in loading capacity and efficacy. Antitumour active compounds such as doxorubicin, paclitaxel, docetaxel and norcantharidin are used as drug carriers. It is evident that chitosan, with its low molecular weight, is a useful carrier for molecular drugs requiring targeted delivery. The antioxidant scavenging activity of chitosan has been established by the strong hydrogen-donating ability of chitosan. The low molecular weight and greater degree of quarternization have a positive influence on the antioxidant activity

Novel methylene blue staining technique for localizing small esophageal leiomyomas during thoracoscopic enucleation.

PubMed

Zhang, Z; Ai, B; Liao, Y; Liu, L; Liu, M

2016-11-01

The treatment of choice for leiomyoma, the most common benign esophageal tumor, is thoracoscopic enucleation. One of the most difficult aspects of thoracoscopic enucleation is the precise localization of small tumors (≤1.5 cm) and tumors without external protrusion. No simple, feasible solutions to this problem are available. We developed a novel methylene blue staining technique to localize small esophageal leiomyomas and evaluated the feasibility of our technique. Between January 2013 and July 2014, eight patients with small esophageal leiomyomas (≤1.5 cm) underwent thoracoscopic enucleation in Tongji Hospital. Preoperative endoscopic ultrasonography was performed in all patients. The leiomyomas were located in the middle (n = 5) and lower (n = 3) thirds of the esophagus. We preoperatively injected 0.5-1.0 mL methylene blue in the submucosa adjacent to the tumors under standard gastroscope guidance. The entire staining process took about 10 minutes. Staining was successful in all patients. The unstained tumor was exposed after the blue-stained mediastinal pleura, and overlying muscle were incised longitudinally. All procedures were successfully completed without conversion to open surgery. No abnormalities were detected in the esophageal mucosa. The median operating time was 60 minutes (range, 40-90 minutes). Postoperative histopathology confirmed leiomyoma in all patients. The median postoperative hospital stay was 6 days (range, 5-7 days). No major complications, such as esophageal leakage or esophageal diverticulum, occurred. Endoscopic methylene blue staining is safe and feasible for localizing small esophageal leiomyomas during thoracoscopic enucleation. This method will enable precise and easy enucleation. © 2015 International Society for Diseases of the Esophagus.

Hierarchical structure and physicochemical properties of plasticized chitosan.

PubMed

Meng, Qingkai; Heuzey, Marie-Claude; Carreau, Pierre J

2014-04-14

Plasticized chitosan with hierarchical structure, including multiple length scale structural units, was prepared by a "melt"-based method, that is, thermomechanical mixing, as opposed to the usual casting-evaporation procedure. Chitosan was successfully plasticized by thermomechanical mixing in the presence of concentrated lactic acid and glycerol using a batch mixer. Different plasticization formulations were compared in this study, in which concentrated lactic acid was used as protonation agent as well as plasticizer. The microstructure of thermomechanically plasticized chitosan was investigated by X-ray diffraction, scanning electron microscopy, and optical microscopy. With increasing amount of additional plasticizers (glycerol or water), the crystallinity of the plasticized chitosan decreased from 63.7% for the original chitosan powder to almost zero for the sample plasticized with additional water. Salt linkage between lactic acid molecules and amino side chains of chitosan was confirmed by FTIR spectroscopy: the lactic acid molecules expanded the space between the chitosan molecules of the crystalline phase. In the presence of other plasticizers (glycerol and water), various levels of structural units including an amorphous phase, nanofibrils, nanofibril clusters, and microfibers were produced under mechanical shear and thermal energy and identified for the first time. The thermal and thermomechanical properties of the plasticized chitosan were measured by thermogravimetric analysis, differential scanning calorimetric, and DMA. These properties were correlated with the different levels of microstructure, including multiple structural units.

Chitosan functionalized poly-ε-caprolactone electrospun fibers and 3D printed scaffolds as antibacterial materials for tissue engineering applications.

PubMed

Tardajos, Myriam G; Cama, Giuseppe; Dash, Mamoni; Misseeuw, Lara; Gheysens, Tom; Gorzelanny, Christian; Coenye, Tom; Dubruel, Peter

2018-07-01

Tissue engineering (TE) approaches often employ polymer-based scaffolds to provide support with a view to the improved regeneration of damaged tissues. The aim of this research was to develop a surface modification method for introducing chitosan as an antibacterial agent in both electrospun membranes and 3D printed poly-ε-caprolactone (PCL) scaffolds. The scaffolds were functionalized by grafting methacrylic acid N-hydroxysuccinimide ester (NHSMA) onto the surface after Ar-plasma/air activation. Subsequently, the newly-introduced NHS groups were used to couple with chitosan of various molecular weights (Mw). High Mw chitosan exhibited a better coverage of the surface as indicated by the higher N% detected by X-ray photoelectron spectroscopy (XPS) and the observations with either scanning electron microscopy (SEM)(for fibers) or Coomassie blue staining (for 3D-printed scaffolds). A lactate dehydrogenase assay (LDH) using L929 fibroblasts demonstrated the cell-adhesion and cell-viability capacity of the modified samples. The antibacterial properties against S. aureus ATCC 6538 and S. epidermidis ET13 revealed a slower bacterial growth rate on the surface of the chitosan modified scaffolds, regardless the chitosan Mw. Copyright © 2018 Elsevier Ltd. All rights reserved.

A novel thermoresponsive hydrogel based on chitosan.

PubMed

Schuetz, Yannic B; Gurny, Robert; Jordan, Olivier

2008-01-01

Injectable thermosetting chitosan hydrogels are attractive systems for drug delivery and tissue engineering that combine biodegradability, biocompatibility and the ability to form in situ gel-like implants. Thermally-induced gelation relies advantageously on biopolymer secondary interactions, avoiding potentially toxic polymerization reactions that may occur with in situ polymerizing formulations. In view of a biomedical use, such formulations have to be sterilizable and storable on extended periods without losing their thermosetting properties. These two key features have been studied in the present paper. Chitosans from two different sources were added with several phosphate-free polyols or polyoses as gelling agents. Despite a reduction in chitosan molecular weight following autoclaving, the hydrogels prepared with autoclaved chitosan showed the desired thermosetting properties. Hence, chitosan steam sterilization combined with aseptic preparation of the hydrogel allows a sterile formulation to be obtained. Whereas thermosetting hydrogels were shown to be unstable when refrigerated, freezing was shown to be conceivable as a storage method. When trehalose or mannitol was used as stabilizing agent, the formulation reconstituted from a lyophilizate displayed thermosetting properties and was still injectable, paving the way to the development of a clinically utilizable, novel chitosan thermosetting hydrogel.

Methylene Blue to Treat Protamine-induced Anaphylaxis Reactions. An Experimental Study in Pigs.

PubMed

Albuquerque, Agnes Afrodite S; Margarido, Edson A; Menardi, Antonio Carlos; Scorzoni, Adilson; Celotto, Andrea Carla; Rodrigues, Alfredo J; Vicente, Walter Vilella A; Evora, Paulo Roberto B

2016-01-01

To examine if methylene blue (MB) can counteract or prevent protamine (P) cardiovascular effects. The protocol included five heparinized pig groups: Group Sham -without any drug; Group MB - MB 3 mg/kg infusion; Group P - protamine; Group P/MB - MB after protamine; Group MB/P - MB before protamine. Nitric oxide levels were obtained by the nitric oxide/ozone chemiluminescence method, performed using the Nitric Oxide Analizer 280i (Sievers, Boulder, CO, USA). Malondialdehyde plasma levels were estimated using the thiobarbiturate technique. 1) Groups Sham and MB presented unchanged parameters; 2) Group P - a) Intravenous protamine infusion caused mean arterial pressure decrease and recovery trend after 25-30 minutes, b) Cardiac output decreased and remained stable until the end of protamine injection, and c) Sustained systemic vascular resistance increased until the end of protamine injection; 3) Methylene blue infusion after protamine (Group P/MB) - a) Marked mean arterial pressure decreased after protamine, but recovery after methylene blue injection, b) Cardiac output decreased after protamine infusion, recovering after methylene blue infusion, and c) Sustained systemic vascular resistance increased after protamine infusion and methylene blue injections; 4) Methylene blue infusion before protamine (Group MB/P) - a) Mean arterial pressure decrease was less severe with rapid recovery, b) After methylene blue, there was a progressive cardiac output increase up to protamine injection, when cardiac output decreased, and c) Sustained systemic vascular resistance decreased after protamine, followed by immediate Sustained systemic vascular resistance increase; 5) Plasma nitrite/nitrate and malondialdehyde values did not differ among the experimental groups. Reviewing these experimental results and our clinical experience, we suggest methylene blue safely prevents and treats hemodynamic protamine complications, from the endothelium function point of view.

Remediation of coal mining wastewaters using chitosan microspheres.