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.     

The Characteristics of Chitinase Expression in Aeromonas schubertii

In this study, chitinase activity in an incubation broth of Aeromonas schubertii was measured using colloidal chitin azure as the substrate. More specifically, the induction of chitinases due to amendment with various carbon sources was examined. The highest chitinase activity was found following amendment with 0.5–1.0 % chitin powder, whereas the activity increased negligibly due to amendment with other carbon sources, such as glucose, GlcNAc, GlcN, sorbitol, sucrose, cellulose, or starch. The chitinase activity induced by the chitin powder was suppressed when the glucose, GlcNAc, GlcN, or starch was added simultaneously to the medium but was not suppressed by the addition of sorbitol, sucrose, or cellulose. The activity of chitinase in the crude extract was also not directly inhibited by glucose. Taken together, these findings suggest that the induction of chitinase activity depends on the acquisition of suitable carbon sources from the environment and that induction occurs at a regulatory level.     

Crab-Eating Monkey Acidic Chitinase (CHIA) Efficiently Degrades Chitin and Chitosan under Acidic and High-Temperature Conditions

Chitooligosaccharides, the degradation products of chitin and chitosan, possess anti-bacterial, anti-tumor, and anti-inflammatory activities. The enzymatic production of chitooligosaccharides may increase the interest in their potential biomedical or agricultural usability in terms of the safety and simplicity of the manufacturing process. Crab-eating monkey acidic chitinase (CHIA) is an enzyme with robust activity in various environments. Here, we report the efficient degradation of chitin and chitosan by monkey CHIA under acidic and high-temperature conditions. Monkey CHIA hydrolyzed α-chitin at 50 °C, producing N-acetyl-d-glucosamine (GlcNAc) dimers more efficiently than at 37 °C. Moreover, the degradation rate increased with a longer incubation time (up to 72 h) without the inactivation of the enzyme. Five substrates (α-chitin, colloidal chitin, P-chitin, block-type, and random-type chitosan substrates) were exposed to monkey CHIS at pH 2.0 or pH 5.0 at 50 °C. P-chitin and random-type chitosan appeared to be the best sources of GlcNAc dimers and broad-scale chitooligosaccharides, respectively. In addition, the pattern of the products from the block-type chitosan was different between pH conditions (pH 2.0 and pH 5.0). Thus, monkey CHIA can degrade chitin and chitosan efficiently without inactivation under high-temperature or low pH conditions. Our results show that certain chitooligosaccharides are enriched by using different substrates under different conditions. Therefore, the reaction conditions can be adjusted to obtain desired oligomers. Crab-eating monkey CHIA can potentially become an efficient tool in producing chitooligosaccharide sets for agricultural and biomedical purposes.     

甲壳素/壳聚糖在环境治理上的应用

天然高分子化合物甲壳素、壳聚糖具有原料丰富、无毒、易于生物降解等优点,国内外众多学者对它的开发应用展开研究,本文综述了甲壳素、壳聚糖及其衍生物对环境污染物的去除,介绍了它在环境治理尤其是废水处理中的研究和应用情况。     

Poly(epsilon-caprolactone)/chitin and poly(epsilon-caprolactone)/chitosan blend films with compositional gradients: fabrication and their biodegradability

Poly(epsilon-caprolactone) (PCL)/chitin and PCL/chitosan blend films with compositional gradients were successfully fabricated by a dissolution/diffusion method; that is, repeatedly pouring the PCL/chitin (or PCL/chitosan) blend solutions, with variable composition, onto polysaccharide layers. The compositional gradient structure in the resulting films was characterized by polarized optic microscopy, ATR-FT-IR and trans-FT-IR microscopic spectroscopy. Enzymatic degradability of the PCL/chitin and PCL/chitosan blend films with compositional gradients in the presence of lysozyme was compared with those of homogeneous films and two-layer films. It was found that the degradation rate of PCL/chitin blend films with a compositional gradient was far lower than that of the neat chitin film, whereas the degradation rate of PCL/chitosan blend films with a compositional gradient was close to that of the neat chitosan film. The suppression of the chitosan crystallization, which accelerates the enzymatic degradation, at the surface of PCL/chitosan films with a compositional gradient was much more severe than that for PCL/chitin films with a compositional gradient.     

电离辐射技术在甲壳素/壳聚糖改性中的应用

电离辐射技术作为一种材料改性的重要手段在天然高分子甲壳素／壳聚糖的开发研究方向有许多独特的优点,本文在甲壳素／壳聚糖的辐射加工及辐射改性的甲壳素／壳聚糖的应用两方面综述了该领域的最新进展。     

Comparative adsorption studies of indigo carmine dye on chitin and chitosan

The adsorption of indigo carmine dye onto chitin and chitosan from aqueous solutions was followed in a batch system. The ability of these materials to adsorb indigo carmine dye from aqueous solution was followed through a series of adsorption isotherms adjusted to a modified Langmuir equation. The maximum number of moles adsorbed was 1.24 +/- 0.16 x 10(-5) and 1.54 +/- 0.03 x 10(-4) mol g(-1) for chitin and chitosan, respectively. The same interactions were calorimetrically followed and the thermodynamic data showed exothermic enthalpic values of -40.12 +/- 3.52 and -29.25 +/- 1.93 kJ mol(-1) for chitin and chitosan, respectively. Gibbs free energies for the two adsorption processes of indigo carmine dye presented a positive value for chitin and a negative one for chitosan, reflecting that dye/surface interactions are thermodynamic favorable for chitosan and nonspontaneous for chitin at 298.15 K. The interaction processes were accompanied by an increase of entropy value for chitosan (90 +/- 6 J mol(-1)K(-1)) and a decrease for chitin (-145 +/- 13 J mol(-1)K(-1)). Thus, dye/chitosan interaction showed favorable enthalpic and entropic processes, reflecting thermodynamic stability of the formed complex, while dye/chitin interaction showed an exothermic enthalpic value and a highly nonfavorable entropic effect, resulting in a nonspontaneous thermodynamic system.     

A study of embolizing materials for chemo-embolization therapy of hepatocellular carcinoma: antitumor effect of cis-diamminedichloroplatinum(II) albumin microspheres, containing chitin and treated with chitosan on rabbits with VX2 hepatic tumors.

As an effective therapy for hepatocellular carcinoma, hepatic arterial chemo-embolization therapy has been widely used, and many embolizing materials have been extensively investigated. In the present study, we prepared various types of cis-diamminedichloroplatinum(II) (CDDP) albumin microspheres using chitin and chitosan, both of which have attracted considerable attention as new non-toxic biological polymer materials having favorable characteristics such as immune adjuvant activity, biological compatibility, and biodegradation. Hepatic artery of rabbit hepatic cancer models, which had transplanted VX2 tumors, were embolized with various types of microspheres. The anti-tumor effects and tumor-targeting of the microspheres, and the effects of the microspheres administration on the hepatic tissue were investigated. As a result, anti-tumor activity of the microspheres was increased by the addition of chitin-containing or chitosan treated materials; tumor growth rates of chitin addition and chitosan treated groups were approximately 160% and 120%, respectively, and were significantly lower than that of the non-treatment groups with a rate of approximately 580%. However, complete inhibition of tumor growth might have been impossible. Anti-tumor activity was increased by the addition of chitin-containing or chitosan treated materials. Whereas the growth inhibitory effect was insufficient, in order to potentiate anti-tumor activity, higher CDDP contents and sustained release of CDDP at a high level from microsphere and so on should be essentially improved for the near future. The CDDP level in hepatic tissue following the administration of microspheres was increased by adding chitin to the microspheres or by treating the microspheres with chitosan.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fabrication of a chitin/chitosan hydrocolloid wound dressing and evaluation of its bioactive properties

Research on Chemical Intermediates - The aim of this study was to develop a chitin/chitosan hydrocolloid (CCH) wound dressing. Chitosan was cross-linked with tripolyphosphate to prepare chitosan...     

Preparation and release characteristics of cisplatin albumin microspheres containing chitin and treated with chitosan

Cisplatin (CDDP) containing albumin microspheres and microcapsules incorporating biodegradable macromolecules, chitin and chitosan, were prepared, and their CDDP content and releasing ability and susceptibility to various enzymes were examined. Chitin was incorporated during preparation of the microspheres, while chitosan was used to treat preformed microspheres. CDDP content was remarkably increased by chitin; when chitin was incorporated at a concentration of 1.5%, the CDDP content of the microspheres was found to be 16.2% (1.8 times that with no addition of chitin). CDDP release was suppressed by chitin and chitosan. The 50% CDDP release time was about 1.5 h when no chitin was added, but about 16 h was required when chitin was incorporated into the microspheres at a concentration of 1.5%. Chitin and chitosan suppressed the decomposition by protease. The microspheres treated with 70% deacetylated chitosan showed the greatest susceptibility to lysozyme. In conclusion, CDDP release can be controlled by the use of chitin or chitosan, and the microspheres should show no immunogenicity in vivo because of their susceptibility to lysozyme.     

甲壳素/甲壳胺的聚集态结构及性能

制备了不同脱乙酰度的甲壳素,并对脱酰化反应进行了研究,找出了适合不同脱酰度甲壳素的溶剂,探讨了制样温度与甲壳胺膜的结晶形态和力学性能之间的关系,比较了甲壳素、甲壳胺及不同来源甲壳素的结晶形态.     

Wet‐spinning and applications of functional fibers based on chitin and chitosan

A series of novel human‐made functional fibers (biofibers) based on chitin and chitosan are prepared by the wet‐spinning and the post chemical modification of chitosan fiber. The wet‐spinning gives rise to a series of biofibers: chitin, chitosan, chitin‐cellulose, chitosan‐cellulose, chitin‐silk fibroin, chitin‐glycosaminoglycans, chitin‐cellulose‐silk fibroin, chitosan‐tropocollagen, and chitin‐cellulose‐silk fibroin. The post chemical modification of chitosan fiber gives rise to a series of chemically modified fibers: N ‐acylchitosans, N ‐arylidene‐ and N ‐alkylidene‐chitosans, N ‐acetylchitosan (chitin)‐tropocollagen, and chitosan‐transition metal complexes. Some of the current and potential applications of these biofibers are described.     

Biomimetic approach to forming chitin/aragonite composites

Biomimetic materials which display the complexity of biominerals like nacre are synthetically difficult to prepare. The formation of chitin/calcium carbonate composites, where CaCO(3) is present as aragonite, was achieved via reacetylation of preformed chitosan scaffolds followed by the combination of presoaking of chitin templates with mineral solutions in the presence of poly(acrylic acid). The as-synthesised composites are comprised of well-ordered ribbons of aragonite crystals held within an organic matrix, mimicking the structure of nacre.     

Extraction and Characterization of Chitin and Chitosan from Parapenaeus longirostris from Moroccan Local Sources

The contents of the exoskeleton of Parapenaeus longirostris from Moroccan local sources were analyzed and the percentages of inorganic salt, protein, lipid, and chitin were determined. Chitin in the α form was extracted from Parapenaeus longirostris shells by 0.25 M HCl and 1 M NaOH treatment for demineralization and deproteinization, respectively. The obtained chitin was converted into the more useful soluble chitosan. The chemical structure and physico-chemical properties of chitin and chitosan were characterized using Fourier transform-infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The molecular weight (MW) of chitosan was determined by viscometric methods. The degree of acetylation (DA) of chitin and chitosan was determined by the ¹H NMR technique. To the best of our knowledge this is the first report on the extraction and characterization of chitin and chitosan from Parapenaeus longirostris.     

A study of embolizing materials for chemo-embolization therapy of hepatocellular carcinoma: embolic effect of cisplatin albumin microspheres using chitin and chitosan in dogs, and changes of cisplatin content in blood and tissue.

Hepatic artery of dogs was embolized with cisplatin (CDDP) albumin microspheres containing chitin and chitosan to investigate the in vivo CDDP release kinetics from CDDP albumin microspheres, the CDDP cumulative characteristics in the liver, and the influence of microsphere administration on hepatic tissue. Results showed that changes in blood CDDP content were dependent on CDDP albumin microsphere type and that release kinetics were better sustained when chitin was added to the microspheres or when the microspheres were treated with chitosan. In particular, the administration of CDDP in the chitin-containing CDDP chitosan albumin microspheres showed a blood CDDP content of approximately 0.26 micrograms Pt/ml 14 d after administration. The administration of chitin-containing or chitosan treated CDDP microspheres showed a CDDP content in the hepatic tissue of 0.14 to 0.23 micrograms Pt/g 28 d after administration. They also showed better control of CDDP release than those without chitin or chitosan treatment. No CDDP influence on hepatic tissue was observed. We conclude that, even in vivo, chitin and chitosan are effective embolic materials.     

Physico-chemical characteristics and functional properties of chitin and chitosan produced by Mucor circinelloides using yam bean as substrate

Microbiological processes were used for chitin and chitosan production by Mucor circinelloides (UCP 050) grown in yam bean (Pachyrhizus erosus L. Urban) medium. The polysaccharides were extracted by alkali-acid treatment and structural investigations by X-ray diffraction, Fourier transform IR analysis, viscosity and thermal analysis by TG, DTG, and DTA were done. The highest biomass yield (20.7 g/L) was obtained at 96 hours. The highest levels of chitosan (64 mg/g) and chitin (500 mg/g) were produced at 48 and 72 hours, respectively. It was demonstrated that yam bean shows great potential as an economic medium and it is possible to achieve a good yield of chitosan with chemical properties that enable its use in biotechnological applications.     

Bioactive Properties of Chitin/Chitosan—Calcium Phosphate Composite Materials

Calcium phosphate coating over phosphorylated derivatives of chitin/chitosan material was produced by a process based on phosphorylation, Ca(OH)₂ treatment and SBF (simulated body fluid solution) immersion. Chitin/chitosan phosphorylated using urea and H₃PO₄ and then soaked in saturated Ca(OH)₂ solution at ambient temperature, which lead to the formation of thin coatings formed by partial hydrolysis of the PO₄ functionalities, were found to stimulate the growth of a calcium phosphate coating on their surfaces after soaking in 1.5 × SBF solution for as little as one day. The Ca(OH)₂ treatment facilitates the formation of a calcium phosphate precursor over the phosphorylated chitin/chitosan, which in turn encourages the growth of a calcium deficient apatite coating over the surface upon immersion in SBF solution. The bio-compatibility of calcium phosphate compound—chitin/chitosan composite materials was evaluated by cell culture test using L-929 cells. The initial anchoring ratio and the adhesive strength of L-929 cells for composites was higher than that for the polystyrene disk (LUX, control). The results of in-vitro evaluation suggested that the calcium phosphate—chitin/chitosan composite materials were suitable for cell carrier materials.     

壳聚糖的结构特性及其衍生物的应用

壳聚糖由甲壳素经脱乙酰基而得,又称为可溶性甲壳素。壳聚糖的结构特征使其具有了独特的物理化学性质和生物活性。本文介绍了壳聚糖的结构特性、重要的化学性质及衍生物的应用。     

Functional polymer/inorganic hybrid nanoparticles for macrophage targeting delivery of oligodeoxynucleotides in cancer immunotherapy

To efficiently deliver CpG oligodeoxynucleotides (ODN) in cancer immunotherapy, a multifunctional macrophage targeting delivery system was designed and prepared. Mannosylated carboxymethyl chitosan/protamine sulfate/CaCO₃/ODN (MCMC/PS/CaCO₃/ODN) nanoparticles were prepared using a facile self-assembly method. The functional components, including MCMC to endow the nanoparticles with macrophage targeting ability, PS to improve the ODN loading capacity and enhance the cell uptake, and CaCO₃ to encapsulate ODN and induce the favorable pH sensitivity, were introduced to the delivery systems by self-assembly. Due to the mannose mediated endocytosis and the favorable effects of PS in overcoming delivery barriers, MCMC/PS/CaCO₃/ODN nanoparticles exhibit a much higher ODN delivery efficiency and a significantly enhanced immune stimulation capacity as compared with Lipofectamine 2000/ODN complexes. The regulation of NF-κB activity by our ODN delivery system results in dramatically increased production of proinflammatory cytokines including IL-12, IL-6, and TNF-α in RAW264.7 cells. The significantly increased CD80 expression after stimulation by the ODN delivery systems indicates the successful modulation of the macrophage polarity to the anti-tumor M1 phenotype. The multifunctional macrophage targeting delivery system developed has promising applications in delivery of CpG ODN in cancer immunotherapy.     

Cellulose/chitosan hybrid nanofibers from electrospinning of their ester derivatives

A facile approach has been established to generate cellulose/chitosan hybrid nanofibers with full range of compositions by electrospinning of their ester derivatives, cellulose acetate (CA) and dibutyryl chitin (DBC), followed by alkaline hydrolysis to cellulose (Cell) and chitosan (CS). DBC was synthesized by acid-catalyzed acylation of chitin (CHI) with butyric anhydride and the newly formed butyl groups on C3 and C6 were confirmed by FT-IR and ¹HNMR. DBC had robust solubility in acetone, DMAc, DMF, ethanol, and acetic acid, all except ethanol were also solvents for CA, allowing mixing of these ester derivatives. Fiber formation by electrospinning of either DBC or CA alone and together in these common solvents and their mixtures were studied. The 1/1 acetone/acetic acid was found to be the optimal solvent system to generate fibers from either DBC or CA as well as their mixtures at all CA/DBC ratios, resulting in hybrid fibers with diameters ranging from 30 to 350 nm. DBC and CA were well mixed and showed no phase separate in the hybrid fibers. Alkaline hydrolysis (NaOH) of the equal mass CA/DBC nanofibers regenerated Cell and CHI readily via O-deacylation, then proceeded to further deacetylate CHI to CS via N-deacetylation at higher alkaline concentrations and/or temperatures. Under conditions studied, hydrolysis with 5N NaOH at 100 °C for 3 h was optimal to regenerate cellulose/chitosan hybrid nanofibers.