聚乳酸材料的仿生修饰研究进展

聚乳酸是生物可降解、生物相容性材料,但由于存在亲水性差、缺乏细胞识别位点等缺陷,限制了其在生物医学工程中的应用.模拟细胞与基质相互作用的特点以及细胞外基质的特性,通过表面修饰、本体改性和复合加工的方法在聚乳酸中引入蛋白胶原、活性肽、多糖以及羟基磷灰石等生物活性分子,实现聚乳酸的仿生修饰,能够有效提高聚乳酸材料的生物学功能.综述了利用这些生物活性分子对聚乳酸进行仿生修饰的研究进展.     

一种可促进成骨细胞黏附和生长的聚乙二醇接枝聚乳酸材料

用氨基封端聚乙二醇(H2N-PEGNH2)对聚乳酸(PLA)进行了本体改性,通过FITC荧光标记牛血清白蛋白(FITC-BSA)对材料的抗非特异性蛋白吸附性能进行了检测,在材料上体外培养Wistar大鼠成骨细胞,检测了材料的细胞相容性.结果表明:与聚乳酸相比,得到的产物聚乙二醇改性聚乳酸(PPLA)明显降低了对牛血清白蛋白的非特异性吸附,仅为PLA的37.3%,显著促进了成骨细胞的黏附和生长.由于该材料具有良好的亲水性、可降解性、细胞相容性及可反应性,预计在组织工程和药物缓释中有潜在应用.     

聚乳酸接枝多糖类生物仿生材料的研究进展

聚乳酸与多糖都是生物可降解、生物相容性材料,将聚乳酸的力学性能优越性和多糖的生物学优越性能综合利用起来,设计生物仿生材料是一种制备生物医用材料的新手段。文中综合讨论了聚乳酸与多糖接枝改性的最新研究进展,同时对于这类生物仿生材料目前存在的问题以及前景进行了评估。     

壳聚糖季铵盐抗菌剂的研究进展

壳聚糖是自然界中唯一存在的碱性多糖,具有生物可降解性、生物相容性、安全性和抗菌性等优良性能,由于壳聚糖所具有的抗菌性能,其在伤口缝合、处理植物种子、消毒剂、洗手液等方面获得了广泛的应用.季铵盐型壳聚糖衍生物材料是提高壳聚糖抗菌性的重要方向之一,也是抗菌材料研究的热点领域.本文综述了国内外有关壳聚糖季铵盐的不同制备方法,...     

3D打印用PLA基材料功能化改性研究

PLA(聚乳酸)作为当前3D打印领域的热点,具有良好的机械性能、生物可降解性以及化学稳定性等性能,被广泛研究。依据生物可降解材料PLA的性能,本文综述了3D打印PLA功能化改性的研究进展,分析了不同改性剂、复合物对PLA的改性影响,总结了当前改性研究现状,并为后续的改性研究提供新的方向。     

基于原子力显微镜的聚乳酸降解研究

目的 为了探究可降解聚乳酸在单分子层次的降解性能及其降解速率,使聚乳酸材料更好地应用于生物医学领域.方法 采用原子力显微镜在纳米层次上分别研究单个聚乳酸链在水以及酸、碱性溶液中的单分子力谱.结果 通过对其单链拉伸结果进行分析,发现单个聚乳酸分子链在纯水中短时间内发生水解断链的概率较小,可以保持其原有的长链和本征弹性,而在酸、碱性环境中则会在短时间内发生酸、碱微环境导致的加速水解行为,从而使长链聚乳酸分子较短时间内水解成为短链聚乳酸分子.通过对宏观颗粒状聚乳酸材料降解质量损失的分析,也说明酸、碱微环境会加速聚乳酸水解过程.结论 从单分子层次上进一步证明了水解过程中发生微环境的改变对聚乳酸降解速度的改变起着重要作用.     

壳聚糖作为药物缓释材料的研究进展

壳聚糖是几丁质的脱乙酰基衍生物。它具有生物相溶性好、低毒性、生物可降解性及可被吸收利用等特点，因此是一种良好的药物释放载体。综述了壳聚糖微球、壳聚糖纳米粒子、壳聚糖膜和壳聚糖水性凝胶的制备方法，药物缓释效果及其在临床上的应用。     

聚乳酸梯度功能材料的制备与应用研究

聚乳酸是一种具有良好的生物相容性、生物降解性和生物吸收性的高分子材料,近年来,被广泛应用于生物医用及日常生活等领域.梯度功能材料作为一种新型的复合材料,凭借其独特的性能优势受到广泛关注.综述了聚乳酸梯度功能材料的制备方法以及其在国内外应用领域取得的最新研究成果,展望了聚乳酸梯度功能材料未来的发展方向和应用前景.     

SF/COL/PLCL和SF/COL/PLLA静电纺丝三维纳米纤维支架材料的性能研究

以具有良好生物相容性、生物可降解性的聚乳酸-聚己内酯(PLCL)和聚左旋乳酸(PLLA)为原料,通过静电纺丝法,以70∶30为质量比的SF/COL分别和聚左旋乳酸、聚左旋乳酸-己内酯共混制备不同质量比的纳米纤维支架材料。采用X射线衍射、热重分析等方法对复合材料的理化性能进行表征并对其交联前后的性能进行探讨和比较。结果表明,SF/COL与高分子聚合物复合后其分子结构和热稳定性变化不明显,交联后复合纳米纤维支架β化程度、结晶度和热稳定性较交联前均有所增加,能形成稳定的分子构象,热稳定性有所提高,在组织工程中可为特定细胞提供结构支持,有望成为一种新型的组织工程支架材料。     

高分子专利EI

本发明提供了一种采用马来酸酐改性的聚乳酸和生物活性物质为原料,制备生物活性聚乳酸材料的方法及其产物和应用,方法步骤：①直接加入有机二胺或二醇或羟胺或水进行反应;②产物经分离纯化后,在有机交联剂的作用下,加入聚乙二醇（也称聚环氧乙烷）或其衍生物反应;然后,③产物经分离纯化后,在有机交联剂的作用下,再加入生物活性物质反应,或在步骤②在有机交联剂的作用下,直接加入生物活性物质反应,获得生物活性聚乳酸产物。采用本方法,通过改变生物活性物质的种类,可制备具有不同生物活性的聚乳酸材料;也可通过本方法,选择一些药物为反应原料制备高分子药物。这种生物活性聚乳酸可很好地用作组织工程支架、药物靶向缓释载体等。     

Chitin and chitosan fibres: A review

Chitin is the most abundant natural amino polysaccharide and estimated to be produced annually almost as much as cellulose. It has become of great interest not only as an underutilized resource, but also as a new functional material of high potential in various fields and the recent progress in chitin chemistry is quite noteworthy. The purpose of this review is to take a closer look at fibres made of chitin and its derivatives. Based on the current research and existing products, some new and futuristic approaches, in the development of novel fibres and their applications have been thoroughly discussed.     

Bioadhesive properties of poly(alkylcyanoacrylate) nanoparticles coated with polysaccharide

Development of bioadhesive nanoparticles is of great interest to improve drug absorption through the intestinal barrier. Various Polysaccharide-coated poly(alkylcyanoacrylate) nanoparticles were prepared. The bioadhesive properties of the nanoparticles coated with dextran or chitosan in end-on or side-on conformation were evaluated with an ex-vivo adsorption experiment on rat intestine. Results show that diffusion of nanoparticles in mucus layer was governed by the nanoparticle diameter and isotherms of adsorption were influenced by the nature of polysaccharide used. High amount of nanoparticles coated with chitosan can be entrapped in the mucus layer even at low nanoparticle concentration in suspension. When nanoparticle concentration increased, a pseudo-plateau was reached. In the case of dextran-coated nanoparticles, linear increase of adsorption was observed and no saturation phenomenon was highlighted over the range of nanoparticle concentration used in this study. These results suggested that interactions involved in bioadhesion mechanism depended on the nature of polysaccharide. Electrostatic interactions are enhanced between chitosan-coated nanoparticles and glycoproteins of mucus leading to a saturated adsorption phenomenon whereas dextran-coated nanoparticles interacted by non-electrostatic interactions with mucus resulting in a non-saturated phenomenon. Polysaccharides grafted at the nanoparticle surface in the brush conformation appeared more favorable to promote interactions of nanoparticles with glycoproteins of mucus in comparison with the more compact loop conformation of polysaccharide chains.     

High-performance liquid chromatography of proteins on functional polysaccharide-coated silica supports

Dextran-coated silica supports are potentially excellent stationary phases for high-performance liquid chromatography of proteins. These supports combined the advantages of polysaccharide phases with the excellent mechanical characteristics of silica. The passivation of the inorganic phase was obtained by a coating with dextran or agarose substituted with a calculated amount of positively charged diethylaminoethyl (DEAE) functions. The passivation of the silica beads can be improved by a second coating with native polysaccharide. The supports presented minimal non-specific adsorption as tested by high-performance size-exclusion chromatography. Because of their polysaccharidic overlayer, these phases were easily grafted with active ligands like anticoagulant compounds (heparin or functional dextrans) or amidine derivatives and used in high-performance affinity chromatography. The affinity of these active supports for thrombin in solution was evaluated and their performances in affinity chromatography were determined. On these supports, the non-specific interactions were minimized and the importance of the specific binding between the active ligand and thrombin in the overall interaction mechanism was enhanced.This paper was presented at thebiomat 90 Conference.     

Mass spectrometric determination of O-glycosylation sites using beta-elimination and partial acid hydrolysis

The present study demonstrates that treating O-glycosylated peptides with methylamine vapor followed by partial acid hydrolysis is an effective means for locating O-glycosylation site(s). The reaction with methylamine transforms the glycosylated Ser and Thr residues into stable methylamine derivatives with a mass increment of +13 Da relative to nonglycosylated Ser and Thr residues. Peptide sequencing based on partial acid hydrolysis followed by mass spectrometric analysis or in favorable cases by CID-MS/MS enables the determination of the formerly O-glycosylated sites.     

4-Nitro-7-piperazino-2,1,3-benzoxadiazole as a reagent for monitoring of airborne isocyanates by liquid chromatography

4-Nitro-7-piperazino-2,1,3-benzoxadiazole (NBDPZ) is presented as a new reagent for the determination of mono- and diisocyanates in air samples. NBDPZ readily reacts with the airborne analytes, thus yielding the corresponding urea derivatives, which are subsequently separated by means of reversed-phase liquid chromatography. On a phenyl-modified stationary phase, excellent baseline separation for numerous mono- and diisocyanate derivatives is obtained. Both diode array and fluorescence detection are performed with limits of detection of 11-35 and 5-9 nmol/L for the individual derivatives, respectively. In contrast to established derivatizing agents for the analysis of isocyanates, NBDPZ provides for increased selectivity due to the favorable detection wavelengths in the visible range (UV/visible, absorption maximums approximately 480 nm; fluorescence, excitation maximums approximately 470 nm, emission maximums approximately 535 nm). In addition, the high molar absorptivities of the reagent and the derivatives provide excellent sensitivity that is superior to most literature-known methods. Finally, air sampling methods comprising both the use of impingers and test tubes are developed and successfully applied to the determination of isocyanates in gaseous samples. Excellent recovery reaching values of >90% is observed for each of the two techniques investigated.     

Synthesis and characterization of polycationic chitosan-graft-poly (l-lysine)

A type of polysaccharide/polypeptide hydride material, chitosan derivatives with polypeptide side chains, was prepared via ring-opening polymerization of N_ε-carbobenzyloxy-l-lysine NCA initiated by water-soluble chitosan and followed by removing the side-chain protective groups. The graft polymer was investigated through FTIR spectroscopy, proton nuclear magnetic resonance spectroscopy and X-ray diffraction to confirm the structure. Furthermore, the results of the atomic force microscopy (AFM) measurement indicated the chitosan-graft-poly (l-lysine) was a kind of extraordinary polycation.     

聚噻吩及其衍生物热电材料研究进展

近来,聚合物热电材料因其成本低、资源丰富、热导率低等优势被认为是最有前途的热电材料之一。聚噻吩及其衍生物是研究较为广泛的一类聚合物热电材料。综述了近年来聚噻吩、聚噻吩衍生物以及聚噻吩基/无机复合热电材料在热电领域的研究进展。已有研究表明,聚噻吩及其衍生物热电材料具有高的Seebeck系数,其See-beck系数与电导率通常是此消彼长的关系。通过制备低维材料,与高电导率的无机纳米材料复合以及适度掺杂等方法可有效提高聚噻吩及其衍生物的热电性能。     

A New Binder for Pharmaceutical Dosage Forms

Gellan gum is a biodegradable polysaccharide recently approved by the U.S. Food and Drug Administration (FDA) for industrial use as a food additive. The objective of the present investigation was to evaluate its potential use as a binder for pharmaceutical dosage forms. Tablets were prepared with gellan gum and evaluated for tablet characteristics. Efficiency of gellan gum and its effects on various disintegrants were also studied.     

有机太阳能电池阴极界面层概述

体相异质结聚合物太阳能电池因具有质轻、柔韧性好、便于大面积印刷等优点引起了越来越多的关注。近年来,聚合物太阳能电池取得了较大的进步。然而,聚合物太阳能电池要实现商业化大面积制备还需要解决一些科学问题,如电荷的分离、传输和收集效率低等。良好的界面接触对提高器件性能至关重要。本文综述了聚合物太阳能电池界面层的作用及分类,包括无机类、富勒烯类、水/醇溶性中性共轭聚合物、水/醇溶性离子型共轭聚合物电解质、超支化小分子和苝酰亚胺衍生物。     

药用超分子材料环糊精衍生物的安全性研究

目的：综述药用超分子材料环糊精衍生物近年来在国内外的安全性研究进展,以促进国内这方面的研究。方法：从环糊精衍生物在不同制剂应用中的安全性方面概括了其最新研究。结果：环糊精及其衍生物在改善药物理化性质、改进处方、提高药效、降低副作用等方面具有重要价值。除了少数环糊精有较大的毒副作用外,环糊精及其衍生物可以作为安全的药物辅料。结论：有关环糊精及其衍生物的毒副作用的研究尚未完善,如磺丁基醚－β－环糊精的毒副作用以及大部分环糊精及其衍生物的长期毒副作用。我国应大力研究、开发和应用环糊精及其衍生物,以扩展优良的药用辅料。