化学修饰壳聚糖的血液相容性

壳聚糖是无毒、可生物降解、具有生物相容性的天然碱性多糖。本文综述了近年来提高壳聚糖的血液相容性的方法及以壳聚糖为原料制备肝素替代品的研究。壳聚糖分子上接枝血液相容性高分子、引入亲水基团或负电基团、酰化改性等均能提高壳聚糖的血液相容性;以壳聚糖为原料制备肝素的替代品可通过在壳聚糖分子上引入磺酸基,或将壳聚糖氧化成6-羧基壳聚糖后再引入磺酸基来实现。对今后如何进一步提高壳聚糖衍生物的血液相容性研究前景进行了展望。     

双指示剂法测定壳聚糖的脱乙酰度

壳聚糖是甲壳质经浓碱脱乙酰基后得到的衍生物,具有良好的生物相容性和生物可降解性,广泛应用于医药、食品、化妆品、轻工、印染、环保和生物工程等领域[1-2]。壳聚糖脱乙酰度(简称DD%)是指壳聚糖多糖分子氨基上脱去乙酰基的百分比,其高低直接影响到壳聚糖的溶解度、絮凝能力、螯合金属离子能力和N-选择性酰化能力等物化特性,是鉴定壳聚糖产品质量的一个重要指标。目前测定壳聚糖脱乙酰度的方法有酸碱滴定     

新型黄原酸壳聚糖对铅离子的吸附及机理研究

以壳聚糖为原料,先合成O-羧甲基壳聚糖,再和二硫化碳反应制备出新型黄原酸壳聚糖,使用元素分析、FT-IR、UV和TG对其结构进行表征。比较了壳聚糖、O-羧甲基壳聚糖和黄原酸壳聚糖对铅离子的吸附能力,并研究黄原酸壳聚糖对水溶液中铅离子的吸附性能,探讨了铅离子溶液的pH值对吸附的影响和黄原酸壳聚糖对铅离子的吸附热力学。结果表明,黄原酸壳聚糖对铅离子吸附量是壳聚糖的8.37倍,平衡吸附量可达600.6mg/g。XPS表明,吸附过程主要通过吸附剂中的氨基、羧基和黄原酸基团与铅离子发生作用完成。     

磁性壳聚糖微球的制备和应用

磁性壳聚糖微球是通过一定的方法用壳聚糖将磁性材料包埋而形成的磁性微球,其内核为纳米级的磁性金属微粒,外层为壳聚糖.壳聚糖含有大量的氨基和羟基,使其具有特定的理化性质,由此奠定了壳聚糖的许多生物学特性及加工特性的基础.另一方面,其磁性内核使磁性壳聚糖微球具有很好的顺磁性,利用外加磁场可以很方便地进行分离.因此磁性壳聚糖在固定化酶、污水处理、食品工业和生物医药等方面具有广泛的用途,磁性壳聚糖的制备及应用的相关研究也越来越受到重视.本文作者对磁性壳聚糖微球的制备和应用进行评述.     

壳聚糖含磷衍生物的合成、表征及其应用研究

壳聚糖是一种可再生的天然碱性多糖,具有多种优良的特性。但是,由于壳聚糖本身的溶解性很差,只能溶解在一些稀酸中,这就在一定程度上限制了其进一步的研究与应用。因此,通过修饰改性提高其已有功能、赋予新的功能是壳聚糖重要的研究领域。其中,通过磷酸化或磷酰化改性是壳聚糖改性研究的方向之一。本文综述了在壳聚糖链上引入含磷/膦基团合成壳聚糖含磷衍生物的研究进展;介绍并讨论了壳聚糖含磷衍生物的合成及纯化方法;对壳聚糖含磷衍生物结构、性能及表面形貌的表征进行了详细的阐述;对壳聚糖含磷衍生物的应用进行了总结,并展望了壳聚糖含磷衍生物未来的应用前景。     

壳聚糖不饱和羧酸盐聚集行为的研究

以半干法制备了一系列壳聚糖不饱和羧酸盐--壳聚糖水杨酸盐(a1)、壳聚糖苯甲酸盐(a2)、壳聚糖肉桂酸盐(a3)壳聚糖丙烯酸盐(a4)和壳聚糖衣康酸盐(a5).用红外光谱和紫外光谱表征了该产品的结构,以凯氏定氮法测定了羧酸的结合量.结果表明壳聚糖和不饱和羧酸盐是通过壳聚糖上的氨基和羧酸中的羧基发生了成盐反应,羧酸的结合...     

壳聚糖改性技术的新进展Ⅱ交联化、季铵盐化、羧基化改性及其低聚糖衍生物

壳聚糖是一种新型高分子功能材料,自身具有优良的生物性能。为克服其溶解性较差等缺陷,扩大其应用范围,常采用物理和化学的手段对壳聚糖改性,以改善其物理、化学性能。本文是"壳聚糖改性技术的新进展Ⅰ"的下篇,将继续介绍2000年以来国内外关于壳聚糖物理和化学改性方面的最新研究进展,阐释改性途径以及对改性后所得衍生物的相关表征。主要涉及到壳聚糖的交联化改性、季铵盐化改性、羧基化改性以及制备壳聚糖低聚糖衍生物等途径。     

N-羧甲基壳聚糖的制备及其对重金属离子吸附研究

采用氯乙酸和壳聚糖为原料制备了N-羧甲基壳聚糖,并研究了其对重金属离子Pb2+、Co2+、Ni2+、Cd2+的吸附行为。采用了XRD、FT-IR、1H-NMR对N-羧甲基壳聚糖进行了表征,对N-羧甲基壳聚糖的4种金属离子配合物进行了FT-IR表征。结果表明,N-羧甲基壳聚糖对Pb2+、Co2+、Ni2+、Cd2+的吸附能力优于壳聚糖,分子中羧基是主要的螯合基团。     

O-羧甲基壳聚糖的制备及应用研究进展

O_羧甲基壳聚糖是壳聚糖的一种衍生物 ,具有比壳聚糖更优良的特性 ,有着更广阔的应用前景。本文对它的制备、性质、应用 ,特别是其在药物释放及基因治疗方面应用的研究进展进行了综述。     

壳聚糖静电纺纳米纤维的制备和特点

对纯壳聚糖、壳聚糖和聚合物的混合物、壳聚糖和蛋白质的混合物、壳聚糖衍生物、壳聚糖和无机纳米颗粒的混合物等静电纺纳米纤维的制备和特点进行了综述,对部分壳聚糖纳米纤维的应用进行了简述。     

羧甲基壳聚糖在果蔬保鲜中的应用研究进展

综述了羧甲基壳聚糖的特性及其在果蔬的涂膜保鲜中的应用研究进展,讨论了羧甲基壳聚糖的浓度、分子量、pH值、取代度对其特性的影响,介绍了羧甲基壳聚糖对果蔬的涂膜保鲜效果。本文对开发羧甲基壳聚糖在果蔬防腐保鲜方面的应用具有理论指导意义。     

Present and Future Role of Chitin and Chitosan in Food

The conversion of processed discarded material into valuable by‐products and alternative specialty materials has been identified as a timely challenge for food research and development associated with numerous applications of chitinous products. Chitin, chitosan, calcareous chitin, and chitosan, N‐acetylated chitosan, N‐methylene phosphonic chitosan (NMPC), and N‐lauryl‐N‐methylene phosphonic chitosan (LMPC) are being studied as a result of their broad range of food applications. These biopolymers offer a wide range of unique applications including formation of biodegradable films, immobilization of enzymes, preservation of foods from microbial deterioration, as additives (clarification and deacidification of fruits and beverages, emulsifier agents, thickening and stabilizing agents, color stabilization), and dietary supplements. This review summarizes some of the most important developments in this field.     

壳聚糖膜结构与乙醇／水混合液的渗透汽化性能

用渗透汽化膜分离混合液体,纤维素、赛璐玢等作醇/水分离膜有较高的渗透通量,但分离系数低.甲壳素是广泛存在于自然界的一类天然高分子.前文报道了用甲壳素脱乙酰基的产物壳聚糖(CS)作醇/水渗透汽化(PV)分离膜,在一定的原料液浓度下具有较好的选择渗透性.本文讨论CS膜结构对乙醇/水混合液PV性能的影响,并探讨了提高选择性的途径.     

Difference in transfer of magnesium and sodium ions through electrodialytic membranes modified with chitosan

The difference in transfer of magnesium and sodium ions through electrodialytic cation-exchange membranes modified with chitosan was studied. The membranes were modified by electrodeposition of chitosan from solution on the membrane surface in the course of electrodialysis, preliminary sorption of chitosan on the membrane surface from aqueous chitosan hydrochloride, or application of a chitosan film to the dry membrane surface. The Mg²⁺/Na⁺ selectivity of transfer through modified electrodialytic membranes was examined in relation to the current density.     

Using NaCl particles as porogen to prepare a highly adsorbent chitosan membranes

Macroporous chitosan membranes were prepared by using NaCl particles porogen and genipin as cross-linking agent. For characterization and sorption behavior comparison, other genipin cross-linked chitosan membranes were prepared by either freeze drying or by using silica particles as porogen. The mean pore diameter, the porosity, the crystallinity index (CrI) as well as the effect of the drying procedures of these chitosan membranes were examined. NaCl reduced the CrI of the chitosan membrane. The oven drying (OD) procedure decreased the mean pore diameter, the porosity, and increased the CrI of the chitosan membranes when compared with the vacuum drying (VD) procedure. The heat treatment of chitosan membrane in aqueous NaOH to attract silica porogen increased the CrI of the membrane. Under the same conditions, the membranes prepared with NaCl had better sorption performance on RR 189 and Cu²⁺ than other membranes. The maximum sorption capacity (q_e) reached 1836.17 mg RR 189/g chitosan and 151.98 mg Cu²⁺/g chitosan. The pore diameter (d_pore) of the membranes was much larger than the diameter of the adsorbate molecules (d_adsorbate), such that the ratio of d_pore/d_adsorbate had little influence on q_e. The porosity and the amorphous extent of the membranes were almost the same on q_e. When using tyrosinase catalyzing, the hydrocaffeic acid (HCA) grafted on the NaCl treated chitosan membrane was almost 10 times more than on chitosan beads. The chitosan membrane prepared with NaCl can be used as a good adsorbent with high loading capacity for implanting molecules (such as ligands, enzymes, etc.) on.     

壳聚糖-丝心蛋白合金膜的研究(Ⅰ)——合金膜的结构及其对丝心蛋白吸水性和机械性能的改善

通过ＦＴＩＲ、Ｘ射线衍射、ＴＧＡ和ＤＳＣ等手段对壳聚糖－丝心蛋白合金膜的结构进行了表征．结果表明，合金膜中壳聚糖和丝心蛋白之间存在着较强的氢键相互作用，根据Ｘ射线衍射结果并结合合金膜表观均匀透明、扫描电镜观察未发现明显宏观相分离，认为合金膜是基本相容的．同时发现，在丝心蛋白中共混一定量的壳聚糖可以改善其吸水性和机械性能．     

A comparative study on the chitosan membranes prepared from acetic acid and glycine hydrochloride for removal of copper

Application of chitosan-based materials as adsorbents in wastewater treatment has received considerable attention in recent years. This study is concerned with the influence of various parameters of the reaction medium with a metal and a biosorbant on the kinetics of copper biosorption from synthetic solutions. Initially, we prepared pure chitosan-based membranes and those modified in two different ways: chitosan membrane prepared from traditional acetic acid and the membrane prepared from glycine hydrochloride, chitosan membranes modified such as chitosan/polyvinyl alcohol (PVA) blends membrane with different compositions (100/0, 80/20, 50/50, 20/80 and 0/100%) and chitosan membranes cross-linked with glutaraldehyde. The membranes were characterized by FTIR spectroscopy, DSC, and rheological measurements. Then, we studied the kinetics of copper biosorption by the membranes. The results suggest that adding PVA to a chitosan membrane can greatly improve the flexibility and wettability of chitosan membranes. The values attained in equilibrium for the chitosan membranes prepared from glycine hydrochloride (95.5 mg g^?1 for chitosan/PVA 50/50%) exceed those for chitosan membranes prepared from acetic acid (61.5 mg/g for chitosan/PVA 50/50%).     

Development of Reasonably Stable Chitosan Based Proton Exchange Membranes for a Glucose Oxidase Based Enzymatic Biofuel Cell

Chitosan based reasonably stable membranes were prepared as polymeric electrolyte and separator for enzymatic fuel cell applications. Glucose oxidase (GOx) bioanode centered biofuel cell with the developed chitosan membranes performed much better in stability with high current densities than that of the biofuel cell utilizing a 125 μ‐thick perfluorosulfonic acid‐type membrane (i. e. Nafion® 115). Proposed chitosan membrane structural stability was enhanced by employing cellulosic support materials and chemical crosslinking. The effects of pH, buffer type, buffer concentration, temperature on the manufactured chitosan membranes along with the biofuel cell system were investigated. The biofuel cell operation parameters were optimized for the current density and stability aspects and more than 3 mA cm^?2 current density was acquired from the cell at optimum conditions. Operational half‐life of the chitosan membrane was found as higher than the half‐life of the GOx immobilized bioanode. Therefore, this result indicates that chitosan membrane structural stability was not a limiting issue for the biofuel cell lifespan.     

Preparation and characterization of stable chitosan nanofibrous membrane for lipase immobilization

Nanofibrous membrane with a fiber diameter of 80-150 nm was fabricated from mixed chitosan/poly(vinyl alcohol) (PVA) solution by an electrospinning process. Field emission scanning electron microscope and transmission electron microscope were used to characterize the morphology of the nanofibrous membrane. It was found that chitosan nanofibrous membrane with stabilized morphology could be prepared through removing most of PVA from the nascent one with 0.5 M NaOH aqueous solution. This treatment also resulted in an obvious decrease in fiber diameter. The stabilized chitosan nanofibrous membrane was explored as support for enzyme immobilization due to the characteristics of excellent biocompatibility, high surface/volume ratio, and large porosity. Lipase from Candida rugosa was immobilized on the nanofibrous membrane using glutaraldehyde (GA) as coupling reagent. The properties of the immobilized lipase were assayed and compared with the free one. Results showed that, the observed lipase loading on this nanofibrous membrane was up to 63.6 mg/g and the activity retention of the immobilized lipase was 49.8% under the optimum condition. The pH and thermal stabilities of lipase were improved after it was immobilized on the chitosan nanofibrous membrane. In addition, the experimental results of reusability and storage stability indicated that the residual activities of the immobilized lipase were 46% after 10 cycles and 56.2% after 30 days, which were obviously higher than that of the free one.     

然聚电解质壳聚糖/羧甲基壳聚糖配合物膜的研制

制备了一种新型聚电解质膜壳聚糖/羧甲基壳聚糖配合物膜, 并对膜的结构进行了初步表征; 同时考察了不同配比的配合物膜对模型蛋白质溶菌酶的吸附性能. 结果表明, 在碱性条件下(pH＝9.2), 随着羧甲基壳聚糖含量的增加, 膜对溶菌酶的吸附能力也随之增强; 当羧甲基壳聚糖的含量为w＝40%时, 膜的吸附性能较佳, 可达92 mg/g.