甲壳胺的结晶度和结晶形态

首次制得非晶甲壳胺样品,并给出了根据X射线衍射图精确计算甲壳胺结晶度的公式,计算得知甲壳胺的结晶度随脱酰度的增加(74%～85%)而增加,发现甲壳胺的结晶结构和结晶形态与制样条件有关。     

甲壳胺-明胶共混物的研究

甲壳胺 明胶共混物的研究莫秀梅（华东理工大学高分子材料系上海２００２３７）关键词甲壳素，明胶，共混物，红外光谱甲壳胺是甲壳素的脱乙酰基产物，即将甲壳素Ｃ２上的乙酰基脱去变成氨基，因此在甲壳胺分子侧链上增加了一个活泼氨基，从而易于化学改性或共混改性．...     

甲壳胺接枝聚合反应的研究

本文是以过硫酸钾为引发剂，研究甲基丙烯酸甲酯（ＭＭＡ）与甲壳胺的接枝聚合反应．通过对不同脱乙酰度（ｄａ）甲壳胺（ＣＴＳ）的接枝聚合反应条件实验，研究了反应时间，温度，引发剂浓度和单体浓度对接枝聚合反应的影响，从中得到优选的反应条件．在相同条件下，比较不同脱乙酰度甲壳胺及Ｎ－取代甲壳胺的接枝聚合反应结果，表明：甲壳胺中氨基参与了接枝聚合反应的引发过程．     

不同脱乙酰度对壳聚糖表面物理及吸附性能的影响

壳聚糖是甲壳素部分脱乙酰化的产物,脱乙酰度的大小对壳聚糖的性能影响很大。利用碱液法,通过对反应时间的控制,制备了不同脱乙酰度的壳聚糖并对其性能进行了研究。结果表明,随着脱乙酰度的增大,壳聚糖膜的吸水率增加,而对其表面接触角的变化则没有影响。同时,壳聚糖海绵对Ca2+和牛血清蛋白(BSA)的吸附能力也随着脱乙酰度的增大而增加。     

壳聚糖的基质辅助激光解吸电离飞行时间质谱分析

利用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)分析甲壳素脱乙酰化降解产物——壳聚糖,对基质、制样方法等影响MALDI-TOF-MS测定结果的因素进行了研究。实验发现,以2,5-二羟基苯甲酸(DHB)为基质,二次结晶法制样分析壳聚糖,既获得了壳聚糖的分子量信息,又可以推断壳聚糖的脱乙酰度,对壳聚糖的制备及其质量与性能控制有着十分重要的指导意义。     

蘑菇中甲壳素的提取及结构研究

以蘑菇为原料提取甲壳素,并制备壳聚糖。通过滴定法测定由蘑菇制备的壳聚糖的脱乙酰度,用乌氏黏度计测定了比浓黏度,并研究了制备工艺中加热温度和碱处理时间对它们的影响,计算了其产率;对以蘑菇为原料制取的甲壳素、壳聚糖的结构通过红外光谱进行表征。结果表明,在碱处理时间为24h、加热温度为100℃的条件下有较高的脱乙酰度;比浓黏度随着碱处理时间的延长、加热温度的增加都呈下降的趋势;壳聚糖产率为1．69％。制取的甲壳素、壳聚糖的红外光谱图表明,甲壳素在蘑菇中主要是以α-构型存在,α-构型甲壳素在浓碱中经过脱乙酰后生成β-构型的壳聚糖。     

乙酰化甲壳素膜的制备及表征

本文报道了加入二氯甲烷可使甲壳素的乙酰化反应更顺利进行,并提高了产物的乙酰化度,通过红外、X射线衍射分析、拉伸等方法对乙酰化甲壳素膜的结晶结构和力学性能作了表征和测定。     

甲壳胺与Zn(Ⅱ)的配位作用及其红外光谱

甲壳胺是甲壳素脱乙酰基的产物，由于分子中游离氨基的存在，使它对一些金属离子，尤其是过渡金属离子具有较好的螯合能力，因而被作为重金属离子的天然吸附剂和高分子金属催化剂的研究对象［１，２］．目前文献报道的以Ｃｕ（Ⅱ）和Ｐｄ（Ⅱ）的配合物居多，且配合物的制...     

水溶性甲壳素及其膜的制备与表征

通过对高脱乙酰度壳聚糖进行均相乙酰化反应，制得脱乙酰度为51．7％的水溶性甲壳素，产物有很好的水溶性．通过红外光谱、X-射线衍射、差热分析等测试表征了水溶性甲壳素结构．结果表明，水溶性甲壳素的结构发生了较大变化，结晶性显著下降是导致水溶性增加的主要原因．     

NMR、FTIR及电位滴定法测定壳聚糖脱乙酰度

脱乙酰度是影响甲壳素、壳聚糖及其衍生物物化特性和生物活性功能的重要参数。介绍了三种壳聚糖脱乙酰度的测定方法。以^13C交叉极化魔角旋转固体核磁法测定的结果作为参照，对红外光谱法和线性电位滴定法的测定结果进行了分析比较，并分析了不同测定方法的误差来源。     

Structural Investigations of Chitin and Its Deacetylation Products

The structure of crab chitin and chitosan from it with various degrees of deacetylation (DDA) are studied by x-ray diffraction, IR spectroscopy, and microscopy. Deacetylation causes substantial destruction of the chitin crystal structure, makes it amorphous, increases the defectiveness of crystallites as the DDA increases, weakens intermolecular H-bonds, and eliminates the fibrillarity.     

The crystal structure of chitin and chitosan

Roentgenographic studies are performed to investigate the structural changes in chitin under pressure and shear during its solid-state processing using a twin-screw extruder and Bridgman anvils. The structure of chitosan synthesized by the solid-phase method is studied. Deformation under the conditions of dry extrusion grinding at room temperature reduces the crystallinity of the original chitin. Addition of water restores the crystallinity of the material up to the value characteristic of the original chitin. Extrusion processing of chitin at room temperature with addition of water virtually preserves the crystallinity and degree of ordering of the chitin crystal lattice, the same as ordinary dry grinding at an elevated (180°C) temperature. The maximum degree of amorphization of chitin is attained by its processing on Bridgman anvils. Solid-state synthesis of chitosan from chitin leads to a product with a more amorphous structure in comparison with chitosan produced by the suspension method.     

Recent advancement and development of chitin and chitosan-based nanocomposite for drug delivery: Critical approach to clinical research

This review depicts the exposure of chitin and chitosan base multifunctional nanomaterial composites for promising applications in field of biomedical science structure, synthesis as well as potential application from a colossal angle. We elaborated critically each of the chitin and chitosan base nanomaterial with its potential application toward biomedical science. For different biomedical applications it use in form of hydrogels, microsphere, nanoparticles, aerogels, microsphere and in form of scaffold. Due to this it had been blended with different polymer such as starch, cellulose, alginate, lipid, hyaluronic acid, polyvinyl alcohol and caboxymethyl cellulose. In this review article, a comprehensive overview of combination of chitin and chitosan base nanomaterial with natural as well as synthetic polymers and their biomedical applications in biomedical field involving drug delivery system all the technical scientific issues have been addressed; highlighting the recent advancements.     

Acidic Proteases from Monterey Sardine (Sardinops sagax caerulea) Immobilized on Shrimp Waste Chitin and Chitosan Supports: Searching for a By-product Catalytic System

Solid wastes generated from the seafood industry represent an important environmental pollutant; therefore, utilization of those wastes for the development of processing biochemical tools could be an attractive and clean solution for the seafood industry. This study reports the immobilization of semi-purified acidic proteases from Monterey sardine stomachs onto chitin and chitosan materials extracted from shrimp head waste. Several supports (chitosan beads, chitosan flakes, and partially deacetylated flakes) were activated either with genipin or Na-tripolyphosphate and evaluated as a mean to immobilize acidic proteases. The protein load varied within the 67–91 % range on different supports. The immobilization systems based on chitosan beads achieved the highest protein loads but showed the lowest retained catalytic activities. The best catalytic behavior was obtained using partially deacetylated chitin flakes activated either with genipin or Na-tripolyphosphate. According to results, the immobilization matrix structure, as well as acetylation degree of chitin–chitosan used, has considerable influence on the catalytic behavior of immobilized proteases. Partially deacetylated chitin flakes represent a suitable option as support for enzyme immobilization because its preparation requires fewer steps than other supports. Two abundant seafood by-products were used to obtain a catalytic system with enough proteolytic activity to be considered for biotechnological applications in diverse fields.     

Squid chitin as a potential alternative chitin source: Deacetylation behavior and characteristic properties

β-Chitin was isolated from squid pens, and the characteristic chemical and physical properties were elucidated in comparison with those of shrimp chitin, α-chitin. Deacetylation behavior of the squid chitin was first studied to look into the reactivity of β-chitin and also to establish an efficient procedure for preparing squid chitosan. The squid chitin proved to show much higher reactivity in alkaline deacetylation than shrimp chitin. Although it was deacetylated quite easily, the product assumed a dark brown color under the ordinary reaction conditions for shrimp chitosan. Squid chitosan was successfully prepared by repeated alkaline treatments under mild conditions, particularly with high concentration alkali at low temperatures, without appreciable discoloration. The structural characteristics of the squid chitin were discussed on the basis of the IR and x-ray analysis data. The crystalline structure of squid chitin was destroyed easily on deacetylation compared to that of shrimp chitin, and moreover, the resulting squid chitosan was amorphous unlike crystalline shrimp chitosan. The squid chitin was characterized by the remarkable affinity for organic solvents and water. Squid chitin and chitosan also showed much higher hygroscopicity and retention of the absorbed water than shrimp chitin and chitosan and are considered to be useful as highly hydrophilic materials. © 1993 John Wiley & Sons, Inc.     

Current Status and New Perspectives on Chitin and Chitosan as Functional Biopolymers

The natural biopolymer chitin and its deacetylated product chitosan are found abundantly in nature as structural building blocks and are used in all sectors of human activities like materials science, nutrition, health care, and energy. Far from being fully recognized, these polymers are able to open opportunities for completely novel applications due to their exceptional properties which an economic value is intrinsically entrapped. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal and insect sources. Significant efforts have been devoted to commercialize chitosan extracted from fungal and insect sources to completely replace crustacean-derived chitosan. However, the traditional chitin extraction processes are laden with many disadvantages. The present review discusses the potential bioextraction of chitosan from fungal, insect, and crustacean as well as its superior physico-chemical properties. The different aspects of fungal, insects, and crustacean chitosan extraction methods and various parameters having an effect on the yield of chitin and chitosan are discussed in detail. In addition, this review also deals with essential attributes of chitosan for high value-added applications in different fields and highlighted new perspectives on the production of chitin and deacetylated chitosan from different sources with the concomitant reduction of the environmental impact.     

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.     

甲壳素衍生物对烟草抗菌活性影响的研究

研究了不同浓度，不同种类酸溶解和不同脱乙酰度的壳聚糖以及水溶解羧甲基壳聚糖对烟草中主要霉菌的抑菌活性，以及它们对烟丝内在质量，焦油，烟碱等的影响。结果表明：酸溶解壳聚糖和水溶解羧甲基壳聚糖对烟草霉变微生物均具有抑制作用，醋酸溶解的壳聚糖较水溶解的羧甲基壳聚糖效果好，水溶解的羧甲基壳聚糖较柠檬酸溶解的壳聚糖效果好，且随壳聚糖脱乙酰度的升高，抑菌作用增强，使烟草内在品质有所改善，其主流烟气焦油，烟碱释放量也略有降低。     

甲壳质、甲壳胺衍生物保护的贵金属胶体

<正> 高分子保护金属胶体是近年来金属催化剂领域中引人注目的研究课题。它除了具有负载型金属催化剂的优点外,还具备下列新优点:a.胶体分散体系可形成“均相”溶液;b.保护高分子可以屏蔽胶体催化剂,减小毒物或空气的不良影响;c.胶体溶液的透光性能比颗粒要好得多,由此最近高分子保护金属胶体常被用于光化学研究中的催化剂;d.高分子保护金属胶体与普通金属胶体相比较,不仅具有较稳定的特点,而且尺寸小(1—10nm)、分布窄,表现出极高的催化活性和选择性;e.保护高分子对金属的修饰作用,可