Chitin Derivatives Research Articles

Preparation and evaluation of the chitin derivatives for wastewater treatments

The chitin thiocarbonate—Fe(II)H—H2O2 redox system was investigated as the initiator for the graft copolymerization of acrylonitrile and acrylic acid monomers onto chitin powder. The reaction with vinyl monomers onto chitin was carried out under various parameters of the graft copolymerization reaction to elucidate the polymerization behavior in terms of graft yield. Reactions of chitin—acrylonitrile graft copolymer with hydroxyl amine hydrochloride, as well as, sodium hydroxide were conducted in order to obtain chitin—(amidoxime-co-acrylonitrile) and chitin-(acrylate-co-acrylamide) graft copolymers, respectively. The reaction efficiency depends upon the alkali concentration, time, temperature, and on the reactant concentrations. The prepared chitin derivatives were evaluated for use in the wastewater treatments for adsorption and desorption of heavy metal ions as well as acid and basic dyes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1939–1946, 1997

Preparation and evaluation of the chitin derivatives for wastewater treatments

Preparation and evaluation of the chitin derivatives for wastewater treatments

A Novel Two-Phase Composting Process Using Shrimp Shells as an Amendment to Partly Composted Biomass

Shrimp and crab shells as well as other seafood industry residues contain chitin as a major component. Partly degraded (oligomeric) chitin is recognized as an elicitor of plant defense mechanisms and a growth suppressor of pathogenic fungi. A method of composting shrimp shells was developed with the objective of obtaining a compost of good quality and characterized by a significant content of oligomeric chitin. The method consists in mixing peat moss, sawdust and a nitrogen rich biomass such as cow manure and composting them until the thermophilic phase is terminated. The immature compost is then amended with 30 percent of shrimp waste on a dry weight basis, inducing a second thermophilic phase. An enzymatic method was developed to monitor the process of chitin degradation and to determine the most appropriate moment to stop the composting process. It was also shown that the peak value of oligomeric chitin content is accompanied by a decisive drop in ammonium content. The shrimp waste-based composts produced by this novel two-phase method have significantly high levels of disease suppressive chitin derivatives than commercially available composts.

Chitinolytic activity of an endophytic strain of Bacillus cereus.

Bacillus cereus strain 65, previously isolated as an endophyte of Sinapis, was shown to produce and excrete a chitinase with an apparent molecular mass of 36 kDa. The enzyme was classified as a chitobiosidase because it was able to cleave diacetylchitobiose (GlcNAc)2 from the non-reducing end of trimeric chitin derivatives. The chitinase exhibited activity over the pH range 4.5-7.5 and was stable between pH 4.0 and 8.5. The enzyme had an isoelectric point of 6.4. Application of B. cereus 65 directly to soil significantly protected cotton seedlings from root rot disease caused by Rhizoctonia solani.

Surface activity of water soluble amphiphilic chitin derivatives

Chitin was derivatized to extend its applications in the field of water soluble systems. It was first carboxymethylated and then alkylated. Two technics were used for that purpose: ionic surfactants playing the role of counterions form an electrostatic complex, and covalent derivatization. The difference between covalent alkylation and dynamic association (SPEC) is discussed in relation with the length of the alkyl chain and the density of alkylation.

Characterization of Chitin-Based Polymer Hybrids by Temperature-Programmed Analytical Pyrolysis Techniques. 1. Chitin-graft-poly(2-methyl-2-oxazoline)/Poly(vinyl chloride) Blends

Chitin-graft-poly(2-methyl-2-oxazoline)/poly(vinyl chloride) (PVC) blends were characterized by means of temperature-programmed analytical pyrolysis techniques such as temperature-programmed pyrolysis−mass spectrometry (TPPy-MS), TPPy−atomic emission detection (TPPy-AED), and TPPy−gas chromatography (TPPy-GC) mainly focusing on their miscibility and sites of the intermolecular interactions. The blends degraded stepwisely in almost three stages corresponding to the degradation of respective blending polymers. However, each degradation peak temperature changed as a function of the blend composition, in particular that of the first degradation stage mostly corresponding to the dehydrochlorination stage for PVC showed a minimum temperature for the blend with the saturated composition of miscibility. During the dehydrochlorination stage for PVC, many characteristic products formed from the chitin derivative were also evolved, suggesting the intermolecular interactions between PVC and the chitin derivative. Among these, a specific hybrid product, benzoic acid reflecting the segmental interaction between PVC and the chitin derivative was observed only for the blend with the saturated composition of miscibility. The evolution peak temperatures and the amounts of the characteristic degradation products were also correlated to the miscibility of the blends. In addition, the mechanisms of the intermolecular interaction of the blends were discussed.

Synthesis and Antibacterial Activity of Water-soluble Chitin Derivatives

Diethylaminoethyl–chitin (DEAE–chitin) was synthesized by introducing DEAE groups onto the C(6)–OH in chitin. DEAE–chitin was N-deacetylated by heating in aqueous 10% sodium hydroxide containing sodium borohydride to prepare the diethylaminoethyl–chitosan (DEAE–chitosan). In addition, DEAE–chitin was quaternized with ethyl halide to produce triethylaminoethyl–chitin (TEAE–chitin). Their antibacterial activities were evaluated by using colony count against Staphylococcus aureus and Escherichia coli by means of shake flask method. The antibacterial activity was found to increase in order of DEAE–chitin, DEAE–chitosan, TEAE–chitin. DEAE–chitin was hydrolyzed by enzymes to investigate the effect of molecular weight on its antibacterial activities. The antibacterial activity was dependent on the structure, particularly on the molecular weight of chitin derivatives. © 1997 John Wiley & Sons, Ltd.

Synthesis and Antibacterial Activity of Water‐soluble Chitin Derivatives

Diethylaminoethyl–chitin (DEAE–chitin) was synthesized by introducing DEAE groups onto the C(6)–OH in chitin. DEAE–chitin was N-deacetylated by heating in aqueous 10% sodium hydroxide containing sodium borohydride to prepare the diethylaminoethyl–chitosan (DEAE–chitosan). In addition, DEAE–chitin was quaternized with ethyl halide to produce triethylaminoethyl–chitin (TEAE–chitin). Their antibacterial activities were evaluated by using colony count against Staphylococcus aureus and Escherichia coli by means of shake flask method. The antibacterial activity was found to increase in order of DEAE–chitin, DEAE–chitosan, TEAE–chitin. DEAE–chitin was hydrolyzed by enzymes to investigate the effect of molecular weight on its antibacterial activities. The antibacterial activity was dependent on the structure, particularly on the molecular weight of chitin derivatives. © 1997 John Wiley & Sons, Ltd.

Crystal Morphology, Biosynthesis, and Physical Assembly of Cellulose, Chitin, and Chitosan

Cellulose and its chemical analogs chitin and chitosan are abundant and technologically important fibrous polysaccharides. Cellulose and chitin are, respectively, the first [1] and second [2] most abundant natural polysaccharides. Chitosan, though less prevalent in nature, is a useful and easily accessible derivative of chitin. All three polymers are biodegradable, renewable resources with versatile chemical and physical properties. As such, they are the subject of active scientific and commercial scrutiny.

Human enzymatic activities related to the therapeutic administration of chitin derivatives.

Three cases are presented where modified chitins have been extensively administered to volunteers, as dressings for wounded soft and bone tissues, as anticholesterolemic dietary foods, and in the controlled delivery of anti-inflammatory drugs. The interactions of the modified chitins with human enzymes is critically examined. In the context of drug carrier resorption and wound healing, chitooligomers and monomers, generated by lysozyme, N-acetylglucosaminidase and human chitinase, activate macrophages and stimulate fibroblasts, respectively; the effects are production of smooth, vascularized and physiologically normal tissues. In the dietary food area, lipase, amylase, 3-hydroxy-3-methylglutaryl CoA reductase, glucokinase and the enzymes of prostaglandin synthesis are involved in the oral administration of chitosan: lipid adsorption is depressed mainly because of the physical form of the chitosan-lipid aggregates, which are unsuitable as substrates. When chitosan is used as a drug carrier, chitosan-drug complexes are present. The uniqueness of chitosan among polysaccharides is underlined in terms of susceptibility to enzymatic depolymerization, cationicity, supply of cell-activating oligomers, and supply of N-acetylglucosamine for rebuilding of other biopolymers. Advances in molecular recognition and biocompatibility are also presented.

Kinetic aspects of polyelectrolyte adsorption: adsorption of chitin derivatives onto liposomes as a model system.

Carboxymethylchitin (CMC) and Carboxymethyl/Glycolchitin (CO) have been adsorbed onto liposomes at physiological ionic strength (I) and pH using phosphate buffer saline (PBS, I = 154 mM, pH = 7.4). Adsorption isotherms at different polymer weight average molecular weights (Mw), for Positive ([+]) or high surface affinity liposomes (DSPC:CHOL:DMTAP, 5:4:1), and Neutral ([N]) or low surface affinity liposomes (DSPC:CHOL, 1:1), have been obtained at T = 25 degrees C. For all CMCs, the adsorbed amount increases with polymer concentration ([P]zero) and no true plateau is observed. The CMC Mw = 4.19 x 10(5) adsorbed on a positive surface fits Langmuir kinetics with maximal coverage gamma max = 325.4 micrograms/mg (polymer/lipid), and inverse of equilibrium constant K* = 4.743 x 10(-4) mg/ml. For all isotherms the predicted amount of polymer needed to coat the entire surface based on the Radius of Gyration (Rg) is inferior to the amount adsorbed. This fact in conjunction with the dependence of gamma max on the number of adsorption shots, suggests that the adsorption is not thermodynamically but kinetically controlled.

Enzymatic hydrolysis reaction of water-soluble chitin derivatives with egg white lysozyme

Hydrolysis reactions using two kinds of water-soluble chitin derivatives and egg white lysozyme were carried out. The optimum pHs of the lysozyme were 5.0 and 3.8 for CM- and DHP-chitin, respectively. There were large differences in the reactivities, that is, in the case of DHP-chitin the reactivity was 7.9–10% of that for CM-chitin.

Metal-chelating chitin derivatives via reaction of chitosan with nitrilotriacetic acid

Chitosan was cross-linked to various extents with nitrilotriacetic acid in the presence of a water-soluble carbodiimide in homogeneous solution, and was then fully N-acetylated. The structure of the nitrilotriacetic acid residues attached to the chitin backbone was determined by acid-base titration. It was shown that the chitin derivatives contained both iminodiacetate and iminomonoacetate residues which form 1:1-type complexes with copper ions. The chitin gels obtained swelled reversibly with water and behaved like ampholytic cross-linked resins in aqueous solutions of acids and bases.

Efficient Graft Copolymerization of 2-Methyl-2-oxazoline onto Tosyl- and Iodo-Chitins in Solution

Graft copolymerization of 2-methyl-2-oxazoline onto tosyl- and iodo-chitins has been examined. The reaction proceeded efficiently with tosyl-chitin in solution to give chitin derivatives having poly(N-acetylethyleneimine) side chains, and the grafting percentage was 280% under appropriate conditions. Graft copolymerization was also possible with iodo-chitin, but rather sluggish. Hydrolytic degradation of the chitin main chain allowed the isolation of the introduced side chains. The number-average molecular weight of the polyethyleneimine isolated from a graft copolymer with grafting percentage of 160% was 2700, indicating that 18% of the carbon atoms having a tosyloxy group were actually utilized for initiating the graft copolymerization. The resulting graft copolymers showed high affinity for both organic solvents and water, and may be useful as a new type of chitin-derived hybrid materials.

Chitin derivatives. I. Kinetics of the heat-induced conversion of chitosan to chitin

The water-soluble solids comprised of the ionic complex between chitosan and acetic acid, chitosonium acetate, are converted into chitin by heating. The thermally-induced conversion of a water-soluble chitosonium acetate in film form into a water-insoluble chitin film was examined by thermal analysis (DMTA, TGA, DSC, and TMA) and by solid state 13C-NMR spectroscopy. Results indicate that tan δ-transitions occur at increasingly high temperatures, and over progressively wider temperature ranges, as the transformation progresses. Likewise, the storage modulus, log E′, increases as the chitosonium acetate film undergoes “cure” and converts to chitin. Cure kinetic parameters are obtained using the model proposed by Provder et al. modified for glass transition temperature (Tg). The results suggest the existence of two sequential first order reactions, an initial and a late cure reaction, having activation energies of approximately 15 and 21 kcal/mol, respectively. © 1996 John Wiley & Sons, Inc.

Chiral discrimination by HPLC on aryl carbamate derivatives of chitin coated onto microporous aminopropyl silica

Optical resolution of a range of racemic compounds was investigated using bis(aryl carbamate) derivatives of chitin coated onto microporous organosilane-modified silica. The influence on chiral discrimination of factors such as the carbamate/support weight ratio, the nature of polysaccharide, and the influence of the aryl group substituents was investigated. The bis(3,5-dimethylphenyl carbamate) derivative of a noncommerical chitin gave the best results. © 1996 Wiley-Liss, Inc.

Prevention of postoperative adhesions with the chitin derivative N‐O‐carboxymethylchitosan

The ideal barrier agent for the prevention of surgical adhesions has remained elusive. We have examined the ability of a new hydrogel N-O-carboxymethylchitosan, a derivative of chitin with properties similar to the extracellular matrix, to prevent adhesions when applied topically to traumatized mesothelial surfaces. In two rodent adhesion models (pericardial and peritoneal), the application of N-O-carboxymethylchitosan significantly prevented or minimized the formation of scar and fibrosis. According to a scoring system from 0 to 3 (0 = no adhesions and 3 = severe dense adhesions), control groups in each model consistently produced severe dense adhesions (2.9 +/- 0.2, 2.7 +/- 0.3). All treated groups consistently scored less than 1.0, indicating minimal or no fibrosis. The differences between the control and treated groups were statistically significant (p < 0.05). Thus, the application of N-O-carboxymethylchitosan to traumatized mesothelial surfaces may have significant potential in the prevention of postoperative adhesion formation.

Chiral discrimination by HPLC on aryl carbamate derivatives of chitin coated onto microporous aminopropyl silica

Optical resolution of a range of racemic compounds was investigated using bis(aryl carbamate) derivatives of chitin coated onto microporous organosilane-modified silica. The influence on chiral discrimination of factors such as the carbamate/support weight ratio, the nature of polysaccharide, and the influence of the aryl group substituents was investigated. The bis(3,5-dimethylphenyl carbamate) derivative of a noncommerical chitin gave the best results. © 1996 Wiley-Liss, Inc.

Topical application of 70% deacetylated chitin (DAC-70): a new approach to the management of senile erythroderma following eczema

Chitin is a polymer of D-glucosamine, beta-poly-N-acetyl D-glucosamine. The chitin derivative, 70% deacetylated chitin (DAC-70), shows immunopotentiating activity. DAC-70 ointment 3.5% in a white petrolatum base was used to treat defined areas of four patients with senile exfoliative erythroderma following eczema. The effects of DAC-70 were compared with those of glyteer (0.2% soybean tar ointment) with 0.1% dexamethasone. In all patients erythroderma ceased spreading within 1 to 2 weeks in all treated areas. Thus, topically applied 3.5% DAC-70 may be of similar value to glyteer in the treatment of exfoliative erythroderma following eczema.

Increase in epidermal ATPase-positive Langerhans cells following topical application of 70% deacetylated chitin (DAC-70) in DNCB-sensitized contact dermatitis in guinea pigs preliminary report

Chitin is a polymer of D-glucosamine, beta-poly-N-acetyl D-glucosamine. The chitin derivative, 70% deacetylated chitin (DAC-70), is immunopotentiating. The present study was conducted to determine the immunoregulatory events in skin following topical application of DAC-70 to DNCB-sensitized contact dermatitis in guinea pigs. On the 3rd day of treatment, DNCB-induced erythema was reduced in all five guinea pigs treated with 10% or 3.5% DAC-70 ointment. On the 7th day of treatment, ATPase-positive Langerhans cell (LC) density in epidermal sheets was 1021 + 131/mm2 (mean + SD) for 10% DAC-70-treated skin, and 1000 + 130/mm2 for 3.5% DAC-70-treated skin, both values exceeding 782 + 65/mm2 for normal epidermis. The value in DAC-70-treated samples was significantly greater (P < 0.01) than in normal epidermis. DAC-70 thus appears to have an immunoregulatory effect by increasing the number of epidermal LCs.