Preparation of water‐soluble chitosan derivatives and their antibacterial activity

Carboxymethyl chitosan sodium (CMCTS) was synthesized by chitosan and chloroacetic acid under an alkali catalyst. Acrylic acid sodium salt and methylacrylic acid sodium salt were grafted onto CMCTS to obtain copolymers with good water solubility. The graft reaction was carried out at 70°C for 2 h, and ammonium persulfate was used as an initiator. The structure changes of chitosan and its derivatives were investigated by the FTIR. The antibacterial activity of chitosan derivatives against Staphylococcus aureus and Escherichia coli were explored by the viable cell counting method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1357–1361, 2002     

Chelation of chitosan derivatives with zinc ions. I. O,N‐carboxymethyl chitosan

The chelation between O,N‐carboxymethyl chitosan (ONCMCh) and zinc sulfate in aqueous solution was studied by kinetic experiments and characterized by inductively coupled plasma (ICP) and UV spectrophotometry. The experimental data indicated that the chelating processes were greatly controlled by the reaction conditions (i.e., reaction time, temperature, and Zn²⁺ ionic and ligand concentrations). The consequence of chelating Zn²⁺ onto ONCMCh was the formation of complexes with different solubilities. The favorable complexes for ONCMCh‐Zn²⁺ chelate were at the low zinc ionic and ligand concentrations, as well as at the appropriate temperature. The evidence provided by the kinetic parameters and the changes in zinc concentration by ICP analysis further confirmed the plausible complexing mechanisms. While the formation of water‐soluble products was occasioned by the electrostatic attraction mechanism, the water‐insoluble products were predominantly formed by chelation of Zn²⁺ with O,N‐carboxymethyl chitosan. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2246–2253, 2000     

DNA delivery using low molecular water‐soluble chitosan nanocomplex as a biomedical device

We investigate the potential of low molecular water‐soluble chitosan (LMWSC), LMWSC–methoxy polyethylene glycol (MPEG) [LCP], and LMWSC–MPEG–cholesterol (LCP–Ch) as a gene carrier. LMWSC with free‐amine group was formed at the low weight ratio, above a 1:2 weight ratio of plasmid DNA:LMWSC. LCP and LCP–Ch achieved complex formation of above 1:8 and 1:24 by reacting with MPEG and cholesterol (Ch) on the amine‐group, respectively. Particle sizes at the pH 6.5 and 7.0 were about 100–120 nm and 120–160 nm, respectively. The surface charge of the complex also depended on the pH. At pH 6.5, the surface charge of the complex was higher than that at pH 7.0. The zeta potential of the LCP modified with MPEG or of the LCP‐Ch modified with cholesterol has lower positive value than that of LMWSC because of the decrease of the positive charge. The morphologies of the complexes by transmission electron microscope were of spherelike shape with the average diameters of about 100–150 nm. Among the three gene carriers, LCP–Ch/plasmid DNA showed the highest gene expression owing to the hydrophobic interaction between cell surface and cholesterol. No cytotoxicity was observed in the gene carriers investigated in this study at various concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3545–3551, 2006     

Immobilization of a nonspecific chitosan hydrolytic enzyme for application in preparation of water‐soluble low‐molecular‐weight chitosan

A nonspecific chitosan hydrolytic enzyme, cellulase, was immobilized onto magnetic chitosan microspheres, which was prepared in a well spherical shape by the suspension crosslinking technique. The morphology characterization of the microspheres was carried out with scanning electron microscope and the homogeneity of the magnetic materials (Fe₃O₄) in the microspheres was determined from optical micrograph. Factors affecting the immobilization, and the properties and stabilities of the immobilized enzyme were studied. The optimum concentration of the crosslinker and cellulase solution for the immobilization was 4% (v/v) and 6 mg/mL, respectively. The immobilized enzyme had a broader pH range of high activity and the loss of the activity of immobilized cellulase was lower than that of the free cellulase at high temperatures. This immobilized cellulase has higher apparent Michaelis–Menten constant K_m (1.28 mg/mL) than that of free cellulase (0.78 mg/mL), and the maximum apparent initial catalytic rate V_max of immobilized cellulase (0.39 mg mL^?1 h^?1) was lower than free enzyme (0.48 mg mL^?1 h^?1). Storage stability was enhanced after immobilization. The residual activity of the immobilized enzyme was 78% of original after 10 batch hydrolytic cycles, and the morphology of carrier was not changed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1334–1339, 2006     

Blend fibers of polyacrylonitrile and water‐soluble chitosan derivative prepared from sodium thiocyanate solution

A water‐soluble chitosan derivative of N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), synthesized by the reaction of chitosan and glycidyltrimethyl ammonium chloride, and polyacrylonitrile (PAN) were blended using 46% (w/w) NaSCN aqueous solution as a common solvent. The total polymer concentration of blend solution was fixed at 12% (w/w), and the relative composition of PAN/HTCC in the blend solution varied from 0/100 to 80/20 by weight. The PAN/HTCC blend fibers with the appropriate physical property were prepared by a wet spinning and drawing process. The effect of HTCC content on the structural change, miscibility, and ability to be dyed of the blend fibers was investigated. The optical and scanning electron microscopic observation gave no indication of phase separation up to 20% HTCC content. Differential scanning calorimetry and dynamic mechanical measurements of the blend fibers show single glass transition temperatures that increase with increasing blend ratio of HTCC. All the experimental results exhibit that the blends are miscible on the molecular scale. The blend fibers could be dyed with an acid dye. This enhanced ability of the blend fibers to be dyed with acid dyes could be useful for one‐step dyeing when mixed with other fibers, such as wool and nylon. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1620–1629, 2001     

壳聚糖及其衍生物在水处理中的应用新进展

天然高分子聚合物壳聚糖具有原料丰富、无毒、易于生物降解等优点,在水处理方面的应用日益广泛,不断有新方法和新技术产生.综述了近几年来壳聚糖及其衍生物在含重金属离子废水,染料废水、食品工业废水和含酚废水处理中的应用新进展.     

DNA adsorption on poly(N,N‐dimethylacrylamide)‐grafted chitosan hydrogels

In this study, poly(N,N‐dimethylacrylamide) grafted chitosan (PDMAAm‐g‐CT) hydrogels were prepared for deoxyribonucleic acid (DNA) adsorption. Instead of directly grafting the N,N‐dimethylacrylamide (DMAAm) monomer onto the chitosan (CT) chains, poly(N,N‐dimethylacrylamide) with carboxylic acid end group (PDMAAm‐COOH) was firstly synthesized by free‐radical polymerization using mercaptoacetic acid (MAAc) as the chain‐transfer agent and then grafted onto the CT having amino groups. The synthesis of PDMAAm‐COOH and its grafting onto the CT chains were confirmed by attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy. From gel permeation chromatography measurements, the number‐average molecular weight (M _n) and polydispersity index of PDMAAm‐COOH were found as 2400 g/mol and 2.3, respectively. The PDMAAm‐g‐CT hydrogels were utilized as the adsorbents in DNA adsorption experiments conducted at +4°C in a trisEDTA solution of pH 7.4. The hydrogels produced with higher PDMAAm‐COOH content exhibited higher DNA adsorption capacity. The DNA adsorption capacity up to 4620 μg DNA/g dry gel could be achieved with the PDMAAm‐g‐CT hydrogels prepared in 80.0 wt % PDMAAm‐COOH feed concentration. This value is approximately seven times higher than that of CT alone. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of new water‐soluble chitosan containing hyperbranched‐vinylsulfonic acid sodium salt and their antimicrobial activities and chelation with metals

In this work, an efficient and simple method to graft a vinylsulfonic acid sodium salt on a poorly water‐soluble chitosan is described. Commercially available low molecular weight chitosan is converted to water‐soluble chitosan containing hyperbranched‐vinylsulfonic acid sodium salt groups. The process comprises the following steps: Michael addition of methyl acrylate, amidation with ethylenediamine, and Michael addition of vinylsulfonic acid sodium salt. A variety of chitosans containing vinylsulfonic acid sodium salt, with improved water solubility, is synthesized by repeating these three steps. The new chitosan derivatives show better antimicrobial activity against Micrococcus luteus ATCC 10240 and Achromobacter xylosoxidans ATCC 2706. In addition, they display better chelating behavior with heavy metals, like cadmium(II), copper(II), and nickel(II), than the starting chitosan. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polyelectrolyte complex beads composed of water‐soluble chitosan/alginate: Characterization and their protein release behavior

Polyelectrolyte complex (PEC) beads were prepared from water‐soluble chitosan (WSC) and alginate complex solution with different ratios by dropping method, and all procedures used were performed in aqueous medium at neutral environment. The structure and morphology of the beads were characterized by IR spectroscopy and scanning electron microscopy (SEM). IR spectroscopy confirmed the electrostatic interactions between amino groups of WSC and carboxyl groups of alginate. SEM showed internal section of the PEC bead, which had porous structure compared with compact structure of alginate beads. The swelling behavior, encapsulation efficiency, and release behavior of bovine serum albumin (BSA) from the beads at different pHs were investigated. PEC beads demonstrated different responses to pH from alginate beads. The ratio of WSC to alginate influenced the encapsulation and release of BSA. At pH 1.2, small amount (< 15%) of BSA was released from the PEC beads except AC12. However, at pH 7.4, a large amount (> 80%) of BSA was released from AL in the first 3 h due to the rapid disintegration of the beads, whereas BSA release was retarded from complex beads due to the forming of PEC. The results suggested that the WSC/alginate beads could be a suitable polymeric carrier for site‐specific protein drug delivery in the intestine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4614–4622, 2006     

Preparation and anti‐clay‐swelling ability of new water‐soluble cellulose derivatives containing quaternary ammonium groups

New water‐soluble cellulose derivatives containing quaternary ammonium groups were prepared by the heterogeneous reactions of hydroxyethyl cellulose with a quaternary chlorohydrin and characterized by reaction parameters and infrared analyses. The dependence of the heterogeneous reaction on the different affecting factors was studied. The cellulose derivatives obtained were investigated for their property as the water‐soluble polymer for inhibiting the swelling of water‐sensitive clay in oilfields. Based on the kinetic curves for clay hydration swelling, a mathematical model that relates linear clay expansion as a function of hydration rate and hydration equilibrium constant was developed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1416–1422, 2001     

Formation of a DNA/N‐dodecylated chitosan complex and salt‐induced gene delivery

An N‐dodecylated chitosan (CS‐12) was synthesized from dodecyl bromide and chitosan and was assembled with DNA to form a polyelectrolyte complex (DNA/CS‐12 PEC). UV was used to examine the thermal stability of DNA embedded in PEC. The results indicate that the incorporation of dodecylated chitosan can enhance the thermal stability of DNA. The analysis of AFM image shows that PEC develops a globule‐like structure composed of 40–115 DNA molecules. Dissociation of PEC was investigated by the addition of low molecular weight electrolytes. The added small molecular salts dissociate the PEC, inducing DNA to release. The ability of Mg²⁺ to dissociate PEC is greater compared to that of Na⁺ and K⁺. From AFM images, it can be visualized that DNA remains intact and undamaged due to the protection from DNase offered by alkylated chitosan. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3391–3395, 2001     

Synthesis of highly swellable hydrogels of water‐soluble carboxymethyl chitosan and poly(ethylene glycol)

Highly swellable hydrogels were produced by crosslinking of high molecular weight carboxymethylated chitosan (CmCHT) with poly(ethylene glycol) (PEG) oligomers. The hydrogel swelling capacity could be controlled via the crosslinking density and ranged from 900% to 5600%. The hydrogels showed good homogeneity with a high interconnected porosity in the swollen state and with nanodomains rich in CmCHT and others rich in PEG diglycidyl ether. Oscillatory frequency sweep analysis showed a storage modulus of 27 kPa for the hydrogel with the highest crosslinking density, which together with the exhibited enzyme degradability with lysozyme at 59 days indicate that these hydrogels have potential use in delivery systems or soft tissue regeneration. © 2017 Society of Chemical Industry     

Studies on the interaction of DNA and water‐soluble polymeric Schiff base–nickel complexes

The modes and activities of the interaction of DNA and water‐soluble polymeric Schiff base–nickel complexes, which have been prepared by polymeric analogous reaction, have been discussed according to absorption spectra, circular dichroism spectra, and fluorescent probe method. It is indicated that polymeric matrix effect and increasing solubility in water can increase the interaction of these water‐soluble polymeric metal complexes with DNA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 887–893, 2002; DOI 10.1002/app.10000     

壳聚糖及其衍生物对土壤重金属的稳定化效应

随着工业的发展,特别是采矿冶炼等行业的发展,使含重金属的废弃物进入土壤,造成土壤重金属污染,对环境和人体健康产生极大威胁。本文以湖南怀化某铅锌矿渣堆放地周围污染土壤为研究目标,通过壳聚糖及其衍生物对污染土壤中重金属离子的稳定化实验,筛选出对目标重金属（Cd²⁺、Pb²⁺、Zn²⁺）具有最佳稳定效果的稳定剂,探究了稳定剂对土壤中重金属离子的稳定机理,并在模拟酸雨淋溶条件下研究了最佳稳定剂对重金属离子的长期稳定化效果。稳定化实验结果表明,壳聚糖及其衍生物对土壤重金属离子均有稳定化作用,其中羧甲基壳聚糖的稳定效果最好,其使污染土壤中重金属离子的可迁移性及生物有效性明显降低。通过重金属形态分析、扫描电镜（SEM）及X射线衍射（XRD）分析得出稳定剂与土壤中重金属离子发生反应生成络合物,并通过机理分析进一步验证了羧甲基壳聚糖的稳定效果最好;淋溶实验表明,羧甲基壳聚糖对土壤中重金属离子具有长期稳定性,经其稳定后土壤中重金属离子以更稳定不易迁移的形态存在,且使土壤环境得到改善,增强了土壤本身对重金属离子的稳定。羧甲基壳聚糖有望成为修复重金属（Cd²⁺、Pb²⁺、Zn²⁺）污染土壤的优良稳定剂。     

Structure and properties of water‐soluble p‐carboxybenzyl polysaccharide derivatives

A series of water‐soluble and water‐insoluble heteroxylans, citrus pectin, and both starch components, amylose and amylopectin, were hydrophobically modified by introducing low amounts of p‐carboxybenzyl groups at constant reaction conditions. The achieved degree of substitution ranged from 0.03 to 0.22. The derivatives were characterized by chemical and spectral analyses. They exhibited tensioactive properties evaluated by various surface‐activity tests. The results indicate a weak surface tension‐lowering effect and low foamability of all derivatives. However, significant emulsifying and protein foam‐stabilizing effects were found for most of the studied derivatives, the most pronounced for the modified pectin and acidic xylans. The rheological behavior of the derivatives was investigated by rotational and oscillation rheometry. The results indicated that the hydrophobic interactions lowered significantly the apparent viscosity of the xylan dispersions and introduced changes, particularly in their flow properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1191–1199, 2000     

Preparation and structural characterization of water‐soluble O‐hydroxypropyl chitin derivatives

Water‐soluble hydroxypropyl chitin (HPC) derivatives were prepared by the reaction of chitin with propylene oxide in homogeneous conditions using a dimethylacetamide/5% lithium chloride solvent system. The reaction conditions for a proper substitution of the hydroxypropyl group were an 80°C reaction temperature, 24‐h reaction time, and 48‐h aging time. ¹H‐NMR and ¹³C‐cross‐polarization/magic angle spinning NMR spectroscopy were used for determining the substitution value and reaction site of substitution. It was found that the substitution reaction occurred mainly at the C₆? OH group in the chitin molecules and water‐soluble chitin derivatives could be obtained at a substitution value higher than 0.35, which is known as a critical substitution value. X‐ray diffraction analysis and FTIR spectroscopy showed that the structural characteristics of HPC derivatives were dependent on the substitution value. As the substitution value of the HPC derivative increased the α‐chitin crystal structure changed to the water‐soluble β‐chitin form in higher substitution values. Differences in the interchenic hydrogen bonding, interplanar spacing of the crystal lattice plane, and crystallinity can explain the structural changes upon substitution. The thermal decomposition temperature was also related to the characteristics of the crystalline structure, depending on a critical substitution value. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2624–2632, 2001     

In vitro comparative hemostatic studies of chitin,chitosan, and their derivatives

The effects of chitin, chitosan, and their derivatives on in vitro human blood coagulation and platelet activation were comparatively studied. The coagulation was assessed by the measure of the whole blood clotting time (WHBCT) and plasma recalcification time (PRT). The tested materials were chitin, chitosan, partially N‐acetylated chitosan (PNAC), N,O‐carboxymethylchitosan (NOCC), N‐sulfated chitosan, N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride, and SPONGOSTAN® standard (a positive control). The results revealed that the WHBCTs of whole blood mixed with chitin, chitosan, NOCC, or SPONGOSTAN® standard were significantly decreased with respect to that of the pure whole blood (a blank control) (P < 0.05), while the WHBCT value of whole blood mixed with PNAC was not significantly reduced. However, the presence of PNAC significantly lowered the PRT value, similar to the addition of chitin, NOCC, or SPONGOSTAN® standard. Chitosan was found to reduce PRT, but not significantly. In the platelet adhesion and activation studies, the morphology of platelets adherent to the film surfaces of tested materials was examined using a scanning electron microscopic technique. Because of their effective coagulation activites, chitosan, PNAC, and NOCC were further evaluated to determine how platelets behaved when in contact with these film samples for given periods. It was found that NOCC activated platelets most effectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 445–451, 2006     

Microencapsulation of water‐soluble herbicide by interfacial reaction. I. Characterization of microencapsulation

A new microencapsulation was established in which small microcapsules with a hydrophilic polymeric wall could be fabricated, capsulizing the water‐soluble content. The new microencapsulation is based on an emulsion interfacial reaction technique that combines the characteristics of an interfacial reaction and conventional emulsion processes. In this technique, hydrophilic polymers [poly(vinyl alcohol) and chitosan] were used as the wall material of the microcapsules. The microencapsulation process was composed mainly of the following steps: preparation of a water/oil (w/o) emulsion 1 containing hydrophilic polymers and a water‐soluble core material and w/o emulsion 2 containing a water‐soluble crosslinking agent and catalyst; the formation of microcapsules by mixing emulsion 1 and emulsion 2; and washing and drying the formed microcapsules. In the new technique an insoluble polymer film was formed easily by the fast crosslinking reaction on the surface of tiny emulsified polymer solution particles in contact with the emulsified crosslinking agent solution particles under mixing with high speed agitation. Thereby, small stable microcapsules were formed. The emphasis in this study was on the establishment of the microencapsulation process by which microcapsules were formed and controlled. The microencapsulation was characterized by analysis of the size distribution of microcapsules fabricated with process conditions. The clarification of the effect of the preparation conditions was also made on the morphology and diameter of the microcapsules. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1645–1655, 2000     

壳聚糖及其衍生物对重金属吸附性能的研究

壳聚糖分子中含有大量的氨基和羟基,可以进行多种化学改性,得到相应的衍生物。改性前后的壳聚糖对重金属都具有吸附作用,可以作为重金属离子的富集剂。文章综述了近年来壳聚糖及其衍生物在吸附重金属方面的研究进展,对比了不同产品对重金属的吸附容量和选择性,以及它们所适用的条件。文章指出,进一步开发水溶性和螯合能力优良的壳聚糖衍生物是今后研究的方向。     

Preparation and adsorption behavior of macrocyclic tetra‐amine derivatives of chitosan

The new macrocyclic polyamine derivatives of chitosan were synthesized by reacting epoxy‐activated macrocyclic tetra‐amine with the C6 hydroxyl or C2 amino group in chitosan. The obtained copolymers (CTS‐OM, CTS‐NM) contain amino functional groups, the secondary amines, and more polar hydroxyl groups in its skeleton. Elemental analysis, infrared spectra, and solid‐state ¹³C‐NMR analysis confirmed their structures. The adsorption behavior of the macrocyclic polyamine grafted chitosan for Ag⁺, Pb²⁺, Hg²⁺, and Cr³⁺ was investigated. The experimental results showed that the two novel derivatives of chitosan have high adsorption capacity and good selectivity for some metal ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 407–412, 2005