大豆分离蛋白接枝改性与应用研究进展

随着人们对环保问题和新材料发展的日益重视,大豆分离蛋白由于其生物可降解性、营养价值高、对人体与环境无害、来源广泛等特点而倍受关注.本文介绍了大豆分离蛋白的接枝改性方法及在食品添加剂、包装膜和医用外敷膜材料的基料以及化妆品中的应用,并综述了国内外在改善膜的应用特性方面取得的研究进展.     

大豆分离蛋白结构与性能

大豆分离蛋白是大豆的重要组成部分,含有大量活性基团,具有可再生、可生物降解性等优点,可以成为制备环境友好材料的主要原料。由于大豆分离蛋白的组成和构象会对其功能特性产生明显的影响,因此对其结构和性能之间的关系进行系统的研究无疑会对材料学家在今后开发出新型的具有优异性能的大豆蛋白材料具有相当的帮助。本文首先介绍了大豆分离蛋白的组成、亚基的结构以及对其两种主要成分——β-大豆伴球蛋白（7S球蛋白）和大豆球蛋白（11S球蛋白）的分离方法;然后对大豆分离蛋白在不同条件下的构象研究和其主要物理化学性质,如溶解性和凝胶性的研究进展作了介绍;最后对大豆分离蛋白在薄膜、纤维和塑料等材料领域的应用进行了简要的综述。     

大豆分离蛋白/琼脂糖复合水凝胶

采用简单的物理共混方法,制备一种大豆分离蛋白/琼脂糖降温型复合水凝胶.即在高温下聚乙二醇改性的大豆分离蛋白/琼脂糖混合物呈溶液状态,降温至生理温度37℃或更低温度则形成水凝胶.表征了该复合凝胶的溶胀度、力学性能、细胞毒性和细胞迁移率.结果表明,改性大豆分离蛋白/琼脂糖复合水凝胶具有较高的溶胀度和力学性能,良好的生物相容性和细胞迁移率,在伤口敷料领域显示出潜在的应用.     

壳聚糖改性技术的新进展Ⅰ．烷基化、酰化以及接枝化改性

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,本文介绍了自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,阐释了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烷基化、酰化以及接枝化改性等途径,并列表比较了以上各种手段的改性效果.本文的下篇<壳聚糖改性技术的新进展Ⅱ.交联化、季铵盐化、羧基化改性以及其低聚糖衍生物>将继续介绍基于壳聚糖的其它改性手段的最新进展.     

淀粉基高分子材料的研究进展

概述了近5年国内外在淀粉的化学、物理改性及其作为一种材料使用方面取得的最新研究进展.淀粉的化学改性主要介绍了淀粉的酯化、醚化、氧化、交联、接枝共聚等,而物理改性主要介绍了淀粉分别与黏土、脂肪族聚酯、聚乙烯醇以及纤维素等天然大分子的共混改性,同时还介绍了通过酸化制备淀粉纳米晶.淀粉基材料除了用于制备可生物降解塑料、吸附材...     

可生物降解聚丁二酸丁二醇酯及其共聚物的合成及改性研究进展

聚丁二酸丁二醇酯(PBS)是一种重要的可生物降解聚合物材料,在一定程度上可以缓解由于使用传统聚合物材料造成的"白色污染"问题.其合成和改性研究受到广泛的关注.本论文对PBS的聚合工艺及方法等方面进行了综述,并对PBS材料物理或化学改性进行了阐述.     

有机硅改性苯丙乳液的研究进展

综述了有机硅改性苯丙乳液的机理、方法和聚合技术研究进展.介绍了物理共混法和化学改性法,重点阐述了化学改性法的最新研究进展,并展望了有机硅改性苯丙乳液的发展趋势.     

聚偏氟乙烯膜的改性研究进展

主要介绍了聚偏氟乙烯(PVDF)膜在近年来改性方法的最新研究进展,从辐照改性、等离子体改性、共混改性和化学改性等几方面进行了详细介绍,简要介绍了PVDF膜作为离子交换膜的一些最新应用.     

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。     

改性高分子超滤膜的研究进展

随着超滤膜技术的发展,人们对膜材料的性能不断提出新的要求,其中改善膜的亲水性,提高膜的抗污染能力已成为有待解决的迫切问题.由于单一的膜材料很难同时具有良好的亲水性、成膜性、热稳定性、化学稳定性、耐酸碱性、耐微生物性侵蚀、耐氧化性和较好的机械强度等优点,因此采用膜材料改性或膜表面改性的方法来提高膜的性能,是解决这一问题的关键.本文介绍了目前国内外高分子超滤膜材料改性中常用的化学改性和物理改性方法.其中,化学改性可以通过膜材料和膜表面的化学改性来实现;而物理改性则主要是通过材料改性来实现.     

原子转移自由基聚合法合成大豆分离蛋白-g-聚甲基丙烯酸2-羟乙酯

通过酰胺化反应在大豆分离蛋白(SPI)表面引入溴原子,合成了大分子引发剂SPI-Br,以CuCl和bpy为催化体系,通过原子转移自由基聚合法(ATRP)合成了大豆分离蛋白-g-聚甲基丙烯酸2-羟乙酯(SPI-g-PHEMA).用FTIR1、3C-NMR、GPC对大分子引发剂、接枝产物和接枝物降解链进行结构表征.结果表明,得到了表面接枝聚甲基丙烯酸2-羟乙酯长链的大豆分离蛋白接枝聚合物,用紫外分光光度计(UV)、荧光分光光度计z、eta电位和透射电镜(TEM)表征了接枝产物的溶液性质和微观形态.     

Molecular-level functionalization of electrode surfaces

An ultra-thin film of functional molecule(s) can be deposited on an electrode, which then serves as a device to amperometrically monitor compounds of biological interest. The methods of surface functionalization, mostly on tin oxide (SnO₂) electrodes, include: chemical modification (covalent bond formation between the surface OH group with a functional group of a molecule); the Langmuir-Blodgett technique, where the NH₂ group of a long-chain alkylamine is bound to an enzyme via a small dialdehyde molecule as spacer; and electropolymerization of pyrrole in an electrolyte containing a single enzyme or a sequentially operating bienzyme system. The results of such investigations by the author’s group are presented.     

蛋白质修饰的电化学研究

蛋白质的翻译后修饰对于生命体执行正常的生理功能具有十分重要的作用,是蛋白质科学研究的重要内容.目前研究蛋白质修饰的方法主要有质谱法、亲和层析等,然而由于蛋白质修饰研究的复杂性,迫切需要发掘新的技术手段.电化学方法理论成熟、应用广泛,在生命科学许多领域发挥着越来越重要的作用.蛋白质的体外修饰必将导致蛋白质特定位点基团的变化,可以利用巧妙设计的电化学方法予以表征和分析,以期探明修饰对蛋白质结构和功能的影响.此外,又可以利用电化学定量分析的独特优势快速准确地测定蛋白质修饰中涉及的相关酶活.正因为如此,蛋白质体外修饰的电化学研究已引起越来越多的关注.本文以作者课题组近期研究工作为主,结合国内外同行的相关代表性工作,介绍电化学方法在蛋白质修饰方面的近期研究进展,并探讨了今后的发展方向和趋势.     

两亲性树状聚合物*

树状聚合物及其功能化是近年来高分子科学界的研究热点之一。本文综述了不同类型的树状聚合物,分别有聚酯、聚丙三醇、聚乙烯亚胺等超支化聚合物,聚酰胺-胺、聚丙烯亚胺等树枝状聚合物。通过对树状聚合物末端大量官能团的亲水（亲油）改性可以制备两亲性树状聚合物,改性方法主要有酰胺化反应、酯化反应、麦克尔加成反应等。与通过缩聚反应所得到的上述树状聚合物不同,近年来配位聚合领域出现的通过“链行走”机理形成的树状聚乙烯,引起了高度关注,这方面着重介绍了乙烯与极性单体直接共聚合或者采用链行走与原子转移自由基聚合联用制备两亲性树状乙烯聚合物。最后对两亲性树状聚合物领域的发展前景进行了展望。     

Flexible,high-wettability and thermostable separator based on fluorinated polyimide for lithium-ion battery

To meet the booming demands for lithium-ion battery (LIB), it is practically significant to promote its electrochemical performance and safety. In our work, a novel kind of flexible membrane as separator for LIB is prepared via phase inversion method with soluble polyimide (SPI) containing trifluoromethyl substituent, which is synthesized from 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and 4,4′-oxydiphthalic anhydride (ODPA). The SPI separator shows 5% weight loss temperature (T_d5%) of 535 °C and maintains intrinsic dimension even after heating at 200 °C. The SPI membrane depicts a sponge-like structure with abundant interconnected pores and delivers a dominant porosity (67%). The SPI membrane displays desired electrolyte wettability, validated by contact angle tests (16.2° and 46.8° for SPI membrane and PE separator, respectively) and electrolyte uptake tests (420 and 132% for SPI membrane and PE separator, respectively). The LIB with SPI membrane as separator exhibits nice ionic conductivity (0.92 mS cm^?1) than that with PE separator (0.30 mS cm^?1), and therefore affords better electrochemical performance, such as cycling stability and rate capability.     

PREPARATION AND CHARACTERIZATION OF SOY PROTEIN ISOLATE(SPI)/MONTMORILLONITE(MMT) BIONANOCOMPOSITES

 The bionanocomposites of soy protein isolate (SPI)/montmorillonite (MMT) have been prepared successfully via simple melt mixing, in which MMT was used as nanofiller and glycerol was used as plasticizer. Their structures and properties were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermogravimetric analysis and tensile testing. XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by simple melt processing. The exfoliated MMT layers were randomly dispersed in the protein matrix as MMT content was low (less than 5 wt%), an incomplete exfoliation was evident from SEM results, and some primary particles were observed as the MMT content was high (from 5 wt% to 9 wt%). A significant improvement of the mechanical strength and thermal stability of SPI/MMT nanocomposites has been achieved. Our work suggests that simple melt processing is an efficient way to prepare SPI/MMT nanocomposites with exfoliated structure.     

Why isn't 'standard' heme good enough for c-type and d1-type cytochromes?

This perspective seeks to discuss why biology often modifies the fundamental iron-protoporphyrin IX moiety that is the very versatile cofactor of many heme proteins. A very common modification is the attachment of this cofactor via covalent bonds to two (or rarely one) sulfur atoms of cysteine residue side chains. This modification results in c-type cytochromes, which have diverse structures and functions. The covalent bonds are made in different ways depending on the cell type. There is little understanding of the reasons for this complexity in assembly routes but proposals for the rationale behind the covalent modification are presented. In contrast to the widespread c-type cytochromes, the d1 heme is restricted to a single enzyme, the cytochrome cd1 nitrite reductase that catalyses the one-electron reduction of nitrite to nitric oxide. This is an extensively derivatised heme; a comparison is drawn with another type of respiratory nitrite reductase in which the active site is a c-type heme, but the product ammonia.     

Postpolymerization modification of poly(pentafluorophenyl methacrylate): Synthesis of a diverse water‐soluble polymer library

This article explores the feasibility of poly(pentafluorophenyl methacrylate) (PPFMA) prepared by reversible addition fragmentation chain transfer (RAFT) polymerization as a platform for the preparation of diverse libraries of functional polymers via postpolymerization modification with primary amines. Experiments with a broad range of functional amines and PPFMA precursors of different molecular weights indicated that the postpolymerization modification reaction proceeds with good to excellent conversion for a diverse variety of functional amines and is essentially independent of the PPFMA precursor molecular weight. The RAFT end group, which was well preserved throughout the polymerization, is cleaved during postpolymerization modification to generate a thiol end group that provides possibilities for further orthogonal chain‐end modification reactions. The degree of postpolymerization modification can be controlled by varying the relative amount of primary amine that is used and random polymethacrylamide copolymers can be prepared via a one‐pot/two‐step sequential addition procedure. Cytotoxicity experiments revealed that the postpolymerization modification strategy does not lead to any additional toxicity compared with the corresponding polymer obtained via direct polymerization, which makes this approach also of interest for the synthesis of biologically active polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4332–4345, 2009     

大豆分离蛋白与壳聚糖复合材料的制备

蛋白质与多糖的静电作用是生物体内一个基本医学-化学现象,是实现自组装的主要驱动力,可利用这种非共价作用设计和构筑理想的微结构。 以大豆分离蛋白(Soybean Protein Isolates,SPI)和壳聚糖(Chitosan,CS)为原料,采用浊度法考察了配比、溶液pH值、离子强度和温度对SPI与CS在溶液中相互作用的影响。 结果显示,由于pH值影响静电作用强度,从而成为影响SPI与CS相互作用的主要因素,其中,当pH值为5.5~6.6时,SPI与CS可以实现有效结合。在较低的离子强度下,有利于形成具有紧凑结构的CS/SPI聚集体,较高离子强度下聚集体发生解离。 蛋白质受热发生变性,多肽链上的疏水氨基酸残基暴露在溶液中,导致与壳聚糖链的疏水作用增强。 DLS结果显示,CS与SPI自组装形成了分布均一的纳米粒子,变性后的SPI与CS形成的纳米粒子粒径有所增大,分布均一;经戊二醛交联,粒径有所减小。 SEM显示,壳聚糖单层膜表面存在龟裂现象,与SPI形成双层膜后龟裂消失;同时,单层膜厚度约为300 nm,双层膜厚度约为500 nm。     

Evaluation of proton conductivity of sulfonated polyimide/dihydroxy naphthalene charge‐transfer complex hybrid membranes

Sulfonated polyimide (SPI)/dihydroxynaphthalene (DHN) charge‐transfer (CT) complex hybrid films were investigated as possible alternative for polymer electrolyte membranes in polymer electrolyte fuel cells. SPI/DHN CT complex hybrid films include CT complexes, which might work as electronic conductors, and sulfonic acid units, which could work as proton conductors. Therefore, the origin of the conductivity of SPI/DHN complex hybrid films was evaluated by four‐probe impedance measurements in the through‐plane direction of the films. The obtained conductivity of the CT complex hybrid films increased with the increase of ion exchange capacity of the CT films and the decrease of CT complex concentration in the films. These results indicated that proton transfer dominantly occurred in the CT complex hybrid films. Proton conductivity of the CT complex hybrid films consisting of 2,6‐ or 1,5‐DHN showed the similar values, although the molecular geometries of the CT complex were different. The activation energy values for proton conductivity in the CT films were approximately the same as that of Nafion 212. Water uptake (WU) results were also conducted and suggest that CT complex formation could control the degree of WU of the films and prevent dissolution of SPI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2991–2997