壳聚糖的化学改性及其应用

综述了近年来壳聚糖化学改性研究,从酯化反应、醚化反应、N-烷基化反应、Schiff碱反应、酰化反应、交联和接枝共聚反应等介绍壳聚糖化学改性研究发展现状;并着重阐述了壳聚糖及其衍生物在日用化学品、农业、食品加工业、医药、环保和纺织业等领域中的应用;展望了壳聚糖研究应用的发展方向,尤其是在日用化学品中的应用前景。     

甲壳素与甲壳胺纤维 3.纤维的化学改性

作为天然高分子材料,甲壳素和甲壳胺有许多优良的物化和生物活性。通过化学改性,甲壳素和甲壳胺可以获得更多的性能。总结了甲壳素和甲壳胺的化学衍生物和各种复合材料。     

Synthesis and characterization of biodegradable TPP/genipin co-crosslinked chitosan gel beads

Novel chitosan gel beads were synthesized by a coupled ionic and chemical co-crosslinking mechanism. Tripolyphosphate (TPP) and a naturally occurring crosslinking reagent, genipin, which has been used in herbal medicine, were employed, respectively, as an ionic and a chemical crosslinkers to prepare the chitosan-based networks of gel beads. The competitive crosslinking of chitosan with ionic crosslinker (TPP) and chemical crosslinker (genipin) was characterized by FTIR, UV and EDAX spectroscopy (X-ray energy dispersion) spectroscopy. The variation of characteristic peak of genipin observed from UV spectroscopy and the characteristic peak of tripolyphosphate in crosslinked chitosan-based networks observed from FTIR spectroscopy suggests that the co-crosslinking mechanism is dependent on the pH of TPP/genipin co-crosslinker. The energy profiles of carbon and phosphorus estimated from confirms that chemical crosslinking dominates the co-crosslinking reaction at higher pH condition (pH 7.0 and 9.0) and ionic crosslinking dominates the co-crosslinking reaction at lower pH condition (pH 1.0, 3.0 and 5.0). The pH-dependent ionic/chemical co-crosslinking mechanism shows an obvious effect on the swelling property and enzymatic degradation behavior of prepared chitosan networks. These results reveal that the ionic/chemical co-crosslinked chitosan networks may be suitable for biomedical applications.     

Influence of Chitosan and Chitosan Derivatives on Hydrodynamics and Mass Transfer in a Bubble Contactor

The behavior of chitosan and two kinds of chitosan derivatives in carbon dioxide absorption in a bubble column contactor is analyzed. The effects of absorption type (physical or chemical), polymer type, concentration, and liquid‐phase physical properties on hydrodynamics (bubble size, gas holdup, and specific interfacial area) and mass transfer (absorption rate and mass transfer coefficient) are evaluated.     

广谱水溶性壳聚糖的研究进展

拓宽能够溶解壳聚糖的水介质的pH范围,是克服壳聚糖应用和研究受局限的有效途径,因而一直得到人们广泛的关注。作者综述了近年来改善壳聚糖溶解于宽pH范围水溶液的方法,并简要介绍了水溶性壳聚糖的应用研究。     

壳聚糖改性及其衍生物在水处理中的应用

研究壳聚糖改性及其衍生物在水处理中的应用。壳聚糖衍生物能够有效去除水中重金属离子、COD和色度等,且无二次污染。与传统壳聚糖衍生物相比,壳聚糖复合衍生物更经济、高效,合成性能更为优良的新型壳聚糖衍生物,与其他技术联合使用,对复杂水的处理能力更强。     

壳聚糖及其衍生物对汞离子的吸附研究进展

综述了壳聚糖及其衍生物在废水治理方面除汞的最新进展,介绍了壳聚糖及其衍生物在不同条件下的吸附能力。其中,壳聚糖对Hg(Ⅱ)离子的吸附能力在430～1 127mg/g之间,而壳聚糖衍生物能增加吸附的稳定性和选择性。此外,磁性吸附技术是近年来研究的热点。     

壳聚糖酰胺衍生物保湿性能研究

壳聚糖具有良好的保湿性能 ,但由于不溶于水 ,因此在化妆品中难以应用。虽然它能溶于酸溶液中 ,但会发生降解而不稳定。壳聚糖可与生物有机酸反应制得壳聚糖N -酰化的衍生物 ,2 %的该类衍生物 ,其保湿性明显优于10 %的甘油水溶液 ,而且粘度稳定 ,无降解发生 ,故可在化妆品中用作保湿剂。     

壳聚糖的化学改性(Ⅰ)

壳聚糖是一种带阳离子的天然活性多糖,在一定条件下可以发生降解反应,其降解产物具有比壳聚糖更优良的功能特性,广泛应用于医药、食品、农业及环保等领域。壳聚糖与醛、酮可发生Schiff反应生成相应的醛亚胺或酮亚胺化合物,后者在氢硼化物作用下加氢进一步转化为各种N-烷基类衍生物。文章概述了近年来壳聚糖化学改性方面取得的某些研究进展,主要包括糖类改性,三甲基化、N-琥珀酰化、硫醇化和叠氮化改性,环状糊精改性,冠醚改性,化学接枝改性等。     

Synthesis and characterization of lactobionic acid grafted pegylated chitosan and nanoparticle complex application

A series of chemical modifications of chitosan were conducted by grafting a hydrophilic methoxy poly(ethylene glycol) (MPEG) and a target sugar molecule lactobionic acid (LA). The MPEG was grafted onto C6-OH position of chitosan, and the grafting degree was reduced for chitosan with high degree of depolymerization. The lactobionic acid was proposed to graft onto C2-NH₂ position of chitosan. The LA grafting ratio was dependent on pegylation degree of chitosan, where the flexibility and shielding effect of MPEG hindered LA grafting onto chitosan. The lactobionic acid grafted pegylated chitosan, DADP-CS-(O-MPEG)-(N-LA), successfully provoked DNA condensation into nanoparticle complexes due to electrostatic compaction. The presence of MPEG on DADP-CS-(O-MPEG)-(N-LA) played an important role on preventing nanoparticle aggregation.     

FUNCTIONALIZED CHITOSAN AND ITS USE IN PHARMACEUTICAL,BIOMEDICAL, AND BIOTECHNOLOGICAL RESEARCH

Hybrids of natural polymers with synthetic polymers are of great interest because of their application as biomedical and biodegradable materials. One of the natural polymers that has attracted much recent attention is chitosan, a polysaccharide obtained by alkaline deacetylation of chitin, exhibiting excellent biological properties such as biodegradability in the human body and immunological, antibacterial, and wound-healing activities. Chitosan has also been found to be a good candidate as a support material for gene delivery, cell culture, and tissue engineering. In this review we have presented the current applications of the various types of chitosan derivatives synthesized in the fields of drug delivery, tissue engineering, wound healing, antimicrobials, biotechnology, pharmaceutics, and cosmetics.     

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

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.     

Fabrication of chitosan microspheres for efficient adsorption of methyl orange

In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), and an Energy Dispersive Spectrometer(EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution(coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g~(-1) and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model.The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.     

壳聚糖季铵盐及其衍生物的应用研究进展

壳聚糖是一种天然无毒多糖,可生物降解,具有生物相容性。在实际应用中壳聚糖水溶性差,只能在酸性介质中溶解。为了提高壳聚糖的溶解度并改善其理化及生物特性以扩大其应用范围,有必要对壳聚糖进行化学修饰。壳聚糖季铵盐是一种常见的壳聚糖修饰产物,属于水溶性壳聚糖衍生物,由于骨架上有强正电荷,因此其pH值溶解范围较宽。综述了壳聚糖季铵盐及其衍生物在抗菌活性、基因运载、给药系统、抗凝血材料、传感器等方面的应用进展,提出改进壳聚糖季铵盐及其衍生物的合成路线,可合成一系列生物学性能改良的壳聚糖季铵盐及其衍生物,有望将其应用于特殊领域。     

Renewable antioxidant properties of suspensible chitosan–polypyrrole composites

Conductive polymers have the ability to capture radicals and have become in focus for antioxidant applications of food packaging or biomedical applications. Unfortunately, the conducting polymers such as polypyrrole are difficult to suspense in solution after chemical or electrochemical polymerization. Chitosan, as a natural polymer from chitin, can be dissolved in diluted acetic acid solutions. In the present study, composites suspensible in diluted acetic acid solutions have been produced by the chemical polymerization of pyrrole in chitosan solution using ammonium persulfate (APS) as the oxidant. FTIR and UV–Vis measurements did identify an attachment of polypyrrole to chitosan.In order to optimize the activity and stability of the composites, the ratios of APS: polypyrrole: chitosan were analyzed. The chitosan–polypyrrole composites were formed as membranes (coatings); impedance measurements indicated their conductivity to be in the range of 10^?3–10^?7 S cm^?1. The antioxidant (radical scavenger activity) properties were determined by the di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) assay. The radical scavenger activity of the composites was found renewable by means of electrochemical cycling.     

壳聚糖及其衍生物应用研究进展

介绍了壳聚糖的性质及研究历史,综述了壳聚糖及其衍生物在水处理、膜分离、分析化学、纺织工业、冷却水循环系统的阻垢、液晶及生物医用材料等方面的应用研究,并对壳聚糖的应用研究进行了展望。     

壳聚糖季铵盐及其复合物的研究进展

壳聚糖季铵盐及其复合物是一种很有应用前景的材料,作者综述了壳聚糖季铵盐及其复合物在载基因、载药、抗菌创伤材料、抗凝血材料、水处理材料等领域的研究进展。     

A fundamental study of chitosan/PEO electrospinning

A highly deacetylated (97.5%) chitosan in 50% acetic acid was electrospun at moderate temperatures (25-70 °C) in the presence of a low content of polyethylene oxide (10 wt% PEO) to beadless nanofibers of 60-80 nm in diameter. A systematic quantitative analysis of the solution properties such as surface tension, conductivity, viscosity and acid concentration was conducted in order to shed light on the electrospinnability of this polysaccharide. Rheological properties of chitosan and PEO solutions were studied in order to explain how PEO improves the electrospinnability of chitosan. Positive charges on the chitosan molecule and its chain stiffness were considered as the main limiting factors for electrospinability of neat chitosan as compared to PEO, since surface tension and viscosity of the respective solutions were similar. Various blends of chitosan and PEO solutions with different component ratios were prepared (for 4 wt% total polymer content). A significant positive deviation from the additivity rule in the zero shear viscosity of chitosan/PEO blends was observed and believed to be a proof for strong hydrogen bonding between chitosan and PEO chains, making their blends electrospinnable. The impact of temperature and blend composition on the morphology and diameter of electrospun fibers was also investigated. Electrospinning at moderate temperatures (40-70 °C) helped to obtain beadless nanofibers with higher chitosan content. Additionally, it was found that higher chitosan content in the precursor blends led to thinner nanofibers. Increasing chitosan/PEO ratio from 50/50 to 90/10 led to a diameter reduction from 123 to 63 nm. Producing defect free nanofibrous mats from the electrospinning process and with high chitosan content is particularly promising for antibacterial film packaging and filtration applications.     

壳聚糖及其衍生物对金属离子吸附研究进展

壳聚糖是一种天然高分子,分子中含有大量的氨基和羟基,对金属离子有很好的吸附能力.本文综述了壳聚糖及其衍生物对金属离子的吸附研究情况,并对其发展前景作了展望.     

甲壳素与甲壳胺纤维1.纤维的制备

甲壳素和甲壳胺是广泛存在于动物和植物中的天然高分子材料。近年来,这两个高分子的生物相容性、生物可降解性、对伤口愈合的促进性能和其它一些优异性能在科技和工商界引起了广泛的重视。作为一种天然再生资源,它们在许多领域内都有很广的应用和开发潜力。总结了甲壳素和甲壳胺纤维的生产条件。