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Chitosan Derivatives (chitosan + derivative)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Medical Sciences	25%
Chemistry	21%

Selected Abstracts

Synthesis of Novel Biomimetic Zwitterionic Phosphorylcholine-Bound Chitosan Derivative

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2006
Rong Zeng
Abstract Summary: Water-soluble biomimetic chitosan derivative conjugating zwitterionic phosphorylcholine was efficiently prepared through Atherton-Todd reaction under the mild conditions, and the possible formation mechanism of zwitterionic product was related to the nucleophilic attack of adjacent 3-hydroxyl on the D -glucosamine residue to phosphorus with the help of base. UV absorption and melting behaviors of DNA/phosphorylcholine-bound chitosan derivative showed that the phosphorylcholine-bound chitosan derivative could be a new carrier for long-circulating macromolecular drug delivery. Structure of zwitterionic PC-chitosan. [source]

Contact-Killing Polyelectrolyte Microcapsules Based on Chitosan Derivatives

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010
Di Cui
Abstract Polyelectrolyte-multilayer microcapsules are made by layer-by-layer (LbL) assembly of oppositely charged polyelectrolytes onto sacrificial colloidal particles, followed by core removal. In this paper, contact-killing polyelectrolyte microcapsules are prepared based solely on polysaccharides. To this end, water-soluble quaternized chitosan (QCHI) with varying degrees of substitution (DS) and hyaluronic acid (HA) are assembled into thin films. The quaternary ammonium groups are selectively grafted on the primary amine group of chitosan by exploiting its reaction with glycidyltrimethylammonium chloride (GTMAC) under homogeneous aqueous acidic conditions. The morphology of the capsules is closely dependent on the DS of the quaternized chitosan derivatives, which suggests differences in their complexation with HA. The DS is also a key parameter to control the antibacterial activity of QCHI against Escherichia Coli (E. coli). Thus, capsules containing the QCHI derivative with the highest DS are shown to be the most efficient to kill E. coli while retaining their biocompatibility toward myoblast cells, which suggests their potential as drug carriers able to combat bacterial infections. [source]

Physical Hydrogels of Poly(vinyl alcohol) with Different Syndiotacticity Prepared in the Presence of Lactosilated Chitosan Derivatives

MACROMOLECULAR BIOSCIENCE, Issue 9 2003
Giancarlo Masci
Abstract Poly(vinyl alcohol) (PVA) physical hydrogels were prepared by repeated freeze,thawing cycles using aqueous solutions of two PVA samples having different degrees of syndiotacticity, a-PVA and s-PVA with 55% and 61% of syndiotactic diads, respectively. The hydrogels were prepared in the presence of different amounts of lactosilated chitosan derivatives (LC) of different molecular weight. The PVA stereoregularity was found to have a dramatic effect on the amount of PVA incorporated into the hydrogels, leading to remarkable differences in the swelling degree and porosity of a-PVA and s-PVA hydrogels. A significant amount of LC was retained in the hydrogels after equilibrium swelling. The swelling of the a-PVA hydrogels was found to increase significantly by increasing the amount of LC while it was only slightly increased in the case of s-PVA hydrogels. The amount of LC released after equilibrium swelling was lower when chitosan derivatives with higher molecular weights were used. Increased initial concentrations of LC resulted in much higher porosity of the hydrogels. TGA and DSC studies showed that LC is stabilized by the incorporation in the PVA hydrogels. The melting temperature of the crystalline regions of PVA was not significantly influenced by LC. Conversely, the extension of the crystalline domains increased in the presence of LC. The retention of a chitosan derivative bearing , - D -galactose side chain residues makes these hydrogels potentially useful as scaffolds for hepatocytes culture. Scanning electron micrographs of PVA-LC hydrogels: (a) a-PVA; (b) a-PVA/LC150 80:20; (c) a-PVA/LC150 50:50. [source]

A synergistic chlorhexidine/chitosan combination for improved antiplaque strategies

JOURNAL OF PERIODONTAL RESEARCH, Issue 5 2005
E.-M. Decker
Background:, The minor efficacy of chlorhexidine (CHX) on other cariogenic bacteria than mutans streptococci such as Streptococcus sanguinis may contribute to uneffective antiplaque strategies. Methods and Results:, In addition to CHX (0.1%) as positive control and saline as negative control, two chitosan derivatives (0.2%) and their CHX combinations were applied to planktonic and attached sanguinis streptococci for 2 min. In a preclinical biofilm model, the bacteria suspended in human sterile saliva were allowed to attach to human enamel slides for 60 min under flow conditions mimicking human salivation. The efficacy of the test agents on streptococci was screened by the following parameters: vitality status, colony-forming units (CFU)/ml and cell density on enamel. The first combination reduced the bacterial vitality to ,0% and yielded a strong CFU reduction of 2,3 log10 units, much stronger than CHX alone. Furthermore, the first chitosan derivative showed a significant decrease of the surface coverage with these treated streptococci after attachment to enamel. Conclusions:, Based on these results, a new CHX formulation would be beneficial unifying the bioadhesive properties of chitosan with the antibacterial activity of CHX synergistically resulting in a superior antiplaque effect than CHX alone. [source]

Enhanced oral absorption of paclitaxel in N -deoxycholic acid- N, O -hydroxyethyl chitosan micellar system,

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2010
Hong Li
Abstract The overall goal of this study was to develop a micellar system of paclitaxel (PTX) to enhance its oral absorption. An amphiphilic chitosan derivative, N -deoxycholic acid- N, O -hydroxyethyl chitosan (DHC), was synthesized and characterized by FTIR, 1H NMR, elemental analysis, and X-ray diffraction (XRD) techniques. The degree of substitution (DS) of hydroxyethyl group and deoxycholic acid group ranged from 89.5,114.5% and 1.11,8.17%, respectively. The critical micelle concentration (CMC) values of DHC decreased from 0.26 to 0.16,mg/mL as the DS of deoxycholic acid group increased. PTX was successfully loaded in DHC micelles with a high drug loading (31.68,±,0.14%) and entrapment efficiency (77.57,±,0.51%). The particle size of PTX-loaded DHC micelles ranged from 203.35,±,2.19 to 236.70,±,3.40,nm as the DS of deoxycholic acid group increased. After orally administration of PTX-loaded DHC micelles, the bioavailability was threefold compared with that of an orally dosed Taxol®. The single-pass intestinal perfusion studies (SPIP) showed that the intestinal absorption of micelles was via endocytosis involving a saturable process and a p-glycoprotein (P-gp)-independent way. All these indicated that the DHC micelles might be a promising tool for oral delivery of poorly water-soluble drugs. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4543,4553, 2010 [source]

Potential prospects of chitosan derivative trimethyl chitosan chloride (TMC) as a polymeric absorption enhancer: synthesis, characterization and applications

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2008
Jasjeet K. Sahni
ABSTRACT In recent years, researchers have been working extensively on various novel properties of polymers to develop increased efficiency of drug delivery and improve bioavailability of various drug molecules, especially macromolecules. Chitosan, a naturally occurring polysaccharide, because of its protonated/polymeric nature, provides effective and safe absorption of peptide and protein drugs. Its transmucosal absorption is, however, limited to acidic media because of its strong intermolecular hydrogen bonds. A new partially quaternized chitosan derivative, N-trimethyl chitosan chloride (TMC), has been synthesized with improved solubility, safety and effectiveness as an absorption enhancer at neutral pH and in aqueous environment. It enhances the absorption, especially of peptide drugs, by reversible opening of tight junctions in between epithelial cells, thereby facilitating the paracellular diffusion of peptide drugs. This derivative thus opens new perspectives as a biomaterial for various pharmaceutical applications/drug delivery systems. This review deals with the potential use of the quaternized chitosan derivative as a permeation enhancer for the mucosal delivery of macromolecular drugs along with its other biomedical applications. [source]

The Encapsulation of Bleomycin Within Chitosan Based Polymeric Vesicles Does Not Alter its Biodistribution

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2000
J. SLUDDEN
Polymeric vesicles have recently been developed from an amphiphilic chitosan derivative,palmitoyl glycol chitosan. Their potential as a drug delivery system was evaluated using the anti-cancer compound bleomycin as a model drug. Palmitoyl glycol chitosan (GCP41) was synthesised by conjugation of palmitoyl groups to glycol chitosan. Bleomycin-containing vesicles (669 nm diameter) were prepared from a mixture of GCP41 and cholesterol by remote loading. The vesicles were imaged by freeze-fracture electron microscopy and their in-vitro stability tested. Incubation of the larger vesicles with plasma in-vitro led to a reduction of mean size by 49%, a reaction not seen with control sorbitan monostearate niosomes (215 nm in size). They also showed a higher initial drug release (1 h), but GCP41 and sorbitan monostearate vesicles retained 62% and 63% of the encapsulated drug after 24 h, respectively. The biodistribution of smaller vesicles (290 nm) prepared by extrusion through a 200-nm filter was also studied in male Balb/c mice. Encapsulation of bleomycin into polymeric vesicles did not significantly alter the pharmacokinetics of biodistribution of bleomycin in male Balb/c mice although plasma and kidney levels were slightly increased. It is concluded that the extruded GCP41 vesicles break down in plasma in-vivo and hence are unlikely to offer any therapeutic advantage over the free drug. [source]

Synthesis of Novel Biomimetic Zwitterionic Phosphorylcholine-Bound Chitosan Derivative

Enhancement of Laser Cancer Treatment by a Chitosan-derived Immunoadjuvant,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2005
Wei R. Chen
ABSTRACT A chitosan derivative, glycated chitosan (GC), has been used as an immunostimulant for cancer treatment in laser immunotherapy. The function of GC is to enhance the host immune response after direct cancer cell destruction by a selective laser photothermal interaction. To further test its effects, laser immunotherapy was extended to include several different adjuvants for immunological stimulation and to include photodynamic therapy (PDT) as a different tumor-destruction mechanism. Complete Freund (CF) adjuvant, incomplete Freund (IF) adjuvant and Corynebacterium parvum (CP) were selected for treatment of metastatic mammary tumors in rats, in combination with a selective photothermal interaction. The solution of the immunoadjuvants admixed with indocyanine green (ICG), a light-absorbing dye, was injected directly into the tumors, followed by noninvasive irradiation of an 805 nm laser. Combined with PDT, in the treatment of tumors in mice, GC was administered peritumorally immediately after laser irradiation. The survivals of treated animals were compared with untreated control animals. In the treatment of rat tumors, CF, IF and CP raised the cure rates from 0% to 18%, 7% and 9%, respectively. In comparison, GC resulted in a 29% long-term survival. In the treatment of EMT6 mammary sarcoma in mice, GC of 0.5% and 1.5% concentrations increased the cure rates of Photofrin-based PDT treatment from 38% to 63% and 75%, respectively. In the treatment of Line 1 lung adenocarcinoma in mice, a 1.67% GC solution enabled a noncurative meso -substituted tetra(meta -hydroxy-phenyl)chlorin,based PDT to cure 37% of the tumor-bearing mice. The experimental results of this study confirmed our previous studies, showing that immunoadjuvants played an active role in laser-related cancer treatment and that GC significantly enhanced the efficacy of laser cancer treatment. [source]

Measurement of critical concentration for mesophase formation of chitosan derivatives in both aqueous and organic solutions

POLYMER INTERNATIONAL, Issue 12 2006
Yan-ming Dong
Abstract A novel chitosan derivative, acryloyl chitosan (AcCs), and two N -maleoyl chitosans, MaCs-1 and MaCs-2, with different degrees of substitution were synthesized using completely deacetylated chitosan as raw material under different reaction conditions. AcCs is an amphiphilic chitosan derivative, but MaCs-1 and MaCs-2 are soluble in water and organic solvents respectively. The concentrated solutions of AcCs, MaCs-1 and MaCs-2 all demonstrated mesophases and were investigated using polarizing optical microscopy (POM). Circular dichroism (CD) was also employed for determining the critical concentration for mesophase formation. A broad peak in the visible light region of CD spectra had its origin in the appearance of the mesophase, and arose from the selective reflection of cholesteric helix pitches. The results of CD measurements agreed with those of POM. The critical concentration values for aqueous solutions were much lower than those for organic solutions, which was explained by the strong interactions between the chitosan derivatives and water. Copyright © 2006 Society of Chemical Industry [source]

Application of a fibre-reactive chitosan derivative to cotton fabric as a zero-salt dyeing auxiliary

COLORATION TECHNOLOGY, Issue 3 2004
Sang-Hoon Lim
Cotton fabric has been treated with a fibre-reactive chitosan derivative containing quaternary ammonium groups, O -acrylamidomethyl- N -[(2-hydroxy-3-trimethylammonium)propyl]chitosan chloride (NMA-HTCC). Cotton treated with NMA-HTCC has been dyed with direct and reactive dyes without the addition of salt. The colour yield was higher than that on untreated cotton, despite the addition of a large amount salt in the latter case. After dyeing, cotton treated with NMA-HTCC gave better wash fastness than the untreated cotton. The light fastness was however inferior to that on untreated cotton. The antimicrobial activity of cotton treated with NMA-HTCC against Staphylococcus aureus was considerably lower after dyeing, probably due to the antimicrobial effect of the cationic group on NMA-HTCC being blocked by its combination with the anionic dye. [source]

Contact-Killing Polyelectrolyte Microcapsules Based on Chitosan Derivatives

Photoinitiating polymerization to prepare biocompatible chitosan hydrogels

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008
Xiaohong Hu
Abstract Chitosan hydrogels were prepared from water soluble chitosan derivatives (chitosan-MA-LA, CML) by photoinitiating polymerization under the existence of Irgacure2959 and the irradiation of UV light. The CML was obtained by amidation of the amine groups of chitosan with lactic acid and methacrylic acid. Gelation time of the hydrogel could be adjusted within a range of 5,50 min, and controlled by factors such as the degree of MA substitution, initiator concentration, existence of oxygen, and salt. The dry hydrogel adsorbed tens to hundred times of water, forming a highly hydrated gel. The swelling ratio was smaller at the higher degree of MA substitution, higher pH, and higher salt concentration. Rheological test showed that the hydrogel is elastomeric in the measuring frequency range, with a storage modulus and loss modulus of 0.8,7 kPa and 10,100 Pa, respectively. In vitro culture of chondrocytes demonstrated that the cells could normally proliferate in the extractant of the hydrogels, showing no cytotoxicity at lower initiator concentration. By contrast, the extractant of the hydrogel made by the redox initiating system, i.e., ammonium persulfate (APS) and N,N,N,,N,-tetramethylethylenediamine (TEMED), showed apparent cytotoxicity. Thus, the chitosan hydrogels initiated by the Irgacure2959 have better comprehensive properties, in particular better biocompatibility, and are more suitable for biomedical applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

A synergistic chlorhexidine/chitosan combination for improved antiplaque strategies

Advances and potential applications of chitosan derivatives as mucoadhesive biomaterials in modern drug delivery

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 8 2006
Shruti Chopra
Pharmaceutical technologists have been working extensively on various mucoadhesive polymeric systems to create an intimate and prolonged contact at the site of administration. Chitosan is one of the most promising polymers because of its non-toxic, polycationic biocompatible, biodegradable nature, and particularly due to its mucoadhesive and permeation enhancing properties. Due to its potential importance in controlled drug delivery applications, pharmaceutical scientists have exploited this mucoadhesive polymer. However, chitosan suffers from limited solubility at physiological pH and causes presystemic metabolism of drugs in intestinal and gastric fluids in the presence of proteolytic enzymes. These inherent drawbacks of chitosan have been overcome by forming derivatives such as carboxylated, various conjugates, thiolated, and acylated chitosan, thus providing a platform for sustained release formulations at a controlled rate, prolonged residence time, improved patient compliance by reducing dosing frequency, enhanced bioavailability and a significant improvement in therapeutic efficacy. We have explored the potential benefits of these improved chitosan derivatives in modern drug delivery. [source]

Methylation of Chitosan with Iodomethane: Effect of Reaction Conditions on Chemoselectivity and Degree of Substitution

MACROMOLECULAR BIOSCIENCE, Issue 10 2003
Elisabete Curti
Abstract N,N,N -trimethylchitosan (TMC) was prepared by reacting purified chitosan with iodomethane, in the presence of sodium hydroxide, water and sodium iodide, at room temperature. The reaction medium was N -methyl-2-pyrrolidone. Different samples of TMC were obtained by adding to the reaction medium a fixed volume (5.5 mL) of aqueous NaOH solutions at different concentrations (15, 20, 30 and 40 wt.-%) and carrying out the reactions for 9 or 24 h. The features observed in the 1H and 13C NMR spectra of these chitosan derivatives, in respect of the chemical shift, number and relative intensity of the signals, depended strongly on the excess of NaOH and H3CI added to the reaction medium, but when the lowest excess was employed, the characteristics of the derivative were not affected by the reaction time to the same extent. The average degree of quaternization of these N -methylated derivatives of chitosan ranged from 10.5% to 44.8%, according to the reaction conditions. Increasing the excess of NaOH, in reactions carried out for 9 h, resulted in TMC samples with progressively higher content of trimethylated sites however, the reaction yields were correspondingly lower and O -alkylation was favored in these cases. 1H NMR spectrum of sample [AX]24h dissolved in D2O (Cp,=,10 g/L). [source]

Physical Hydrogels of Poly(vinyl alcohol) with Different Syndiotacticity Prepared in the Presence of Lactosilated Chitosan Derivatives

Insecticidal and fungicidal activity of new synthesized chitosan derivatives

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 10 2005
Entsar I Rabea
Abstract Chitosan, the N -deacetylated derivative of chitin, is a potential biopolysaccharide owing to its specific structure and properties. In this paper, we report on the synthesis of 24 new chitosan derivatives, N -alkyl chitosans (NAC) and N -benzyl chitosans (NBC), that are soluble in dilute aqueous acetic acid. The different derivatives were synthesized by reductive amination and analyzed by 1H NMR spectroscopy. A high degree of substitution (DS) was obtained with N -(butyl)chitosan (DS 0.36) at a 1:1 mole ratio for NAC derivatives and N -(2,4-dichlorobenzyl)chitosan (DS 0.52) for NBC derivatives. Their insecticidal and fungicidal activities were tested against larvae of the cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), the grey mould Botrytis cinerea Pers (Leotiales: Sclerotiniaceae) and the rice leaf blast Pyricularia grisea Cavara (Teleomorph: Magnaporthe grisea (Hebert) Barr). The oral feeding bioassay indicated that all the derivatives had significant insecticidal activity at 5 g kg,1 in artificial diet. The most active was N -(2-chloro-6-fluorobenzyl)chitosan, which caused 100% mortality at 0.625 g kg,1, with an estimated LC50 of 0.32 g kg,1. Treated larvae ceased feeding after 2,3 days; the mechanism of action remains unknown. In a radial hyphal growth bioassay with both plant pathogens, all derivatives showed a higher fungicidal action than chitosan. N -Dodecylchitosan, N -(p -isopropylbenzyl)chitosan and N -(2,6-dichlorobenzyl)chitosan were the most active against B cinerea, with EC50 values of 0.57, 0.57 and 0.52 g litre,1, respectively. Against P grisea,N -(m -nitrobenzyl)chitosan was the most active, with 77% inhibition at 5 g litre,1. The effect of different substitutions is discussed in relation to insecticidal and fungicidal activity. Copyright © 2005 Society of Chemical Industry [source]

Chemical modification of chitosan: synthesis and biological activity of new heterocyclic chitosan derivatives

POLYMER INTERNATIONAL, Issue 2 2008
Mohamed EI Badawy
Abstract BACKGROUND: Numerous works have been published on the chemical modification of chitosan; this polymer is still being modified, leading to various derivatives with improved properties. In the present study, heterocyclic aldehydes including furan-2-carbaldehyde, 5-methylfuran-2-carbaldehyde, 3-pyridine carboxyaldehyde, benzo[d][1,3]dioxole-5-carbaldehyde and 4-oxo-4H -chromene-3-carbaldehyde were reacted with chitosan by a reductive alkylation reaction to produce for the first time five new N -heterocyclic chitosan derivatives to improve the biological activity of chitosan against the most important economic plant pests including fungi and insects, in particular the cotton leafworm Spodoptera littoralis. RESULTS: The chemical structures of the synthesized compounds were confirmed by 1H NMR spectroscopy and the degree of substitution ranged from 0.30 to 0.43. The fungicidal assessment was investigated in vitro using a mycelia radial growth inhibition technique against soil-borne pathogenic fungi Fusarium oxysporum and Pythium debaryanum and the rice leaf blast Pyricularia grisea. The results showed that N -[(5-methylfuran-2-yl)methyl] chitosan was the most active against P. grisea with an EC50 value of 0.919 mg mL,1 while N -(benzo[d][1,3]dioxol-5-ylmethyl) chitosan and N -(methyl-4H -chromen-4-one) chitosan exhibited the most potent fungicidal activity against P. debaryanum and F. oxysporum. An insecticidal bioassay against the larvae of S. littoralis showed that N -(methyl-4H -chromen-4-one) chitosan exhibited a significant growth inhibition and antifeedant activity among the synthesized compounds. CONCLUSION: The chemical modification of chitosan molecule with a heterocyclic moiety led to an enhancement in the biological activity against the plant pathogenic fungi F. oxysporum, P. debaryanum and P. grisea and the cotton leafworm insect S. littoralis. Copyright © 2007 Society of Chemical Industry [source]

Measurement of critical concentration for mesophase formation of chitosan derivatives in both aqueous and organic solutions

One-pot synthesis in aqueous system for water-soluble chitosan- graft -poly(ethylene glycol) methyl ether

BIOPOLYMERS, Issue 6 2006
J. Fangkangwanwong
Abstract Chitosan is functionalized with poly(ethylene glycol) methyl ether (mPEG) at the amino and hydroxyl groups via a single step reaction in a homogeneous aqueous system. A chitosan aqueous solution obtained from the mixture of chitosan and hydroxybenzotriazole (HOBt) in water is a key factor in providing mild conditions to conjugate mPEG by using a carbodiimide conjugating agent. The reaction at ambient temperature for 24 h gives chitosan- g -mPEG with water solubility with mPEG content as high as 42%. This work demonstrates that a water-soluble chitosan,HOBt complex is an effective system for the preparation of chitosan derivatives via the aqueous system without the use of acids or organic solvents. © 2006 Wiley Periodicals, Inc. Biopolymers 82:580,586, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]