PLA大分子单体接枝NVP共聚物的合成与性能

制备了末端为双键的功能化聚乳酸大分子单体(PLA-HEMA),并以此大分子单体与N-乙烯基吡咯烷酮(NVP)进行自由基溶液共聚,合成了具有亲水性PVP-PHEMA主链和疏水性PLA支链的接枝共聚物。用FT-IR1、H-NMR、GPC、DSC、表面接触角测定研究了共聚物的结构与性能。结果表明:共聚物为非晶聚合物;NVP的摩尔投料量对共聚物的性能有显著影响,随NVP投料量增大,共聚物的分子量有所下降,玻璃化转变温度(Tg)增大;由于亲水性PVP和PHEMA链段的引入,共聚物的亲水性优于相应的线型聚乳酸材料。     

聚丙交酯及其共聚物的研究进展

聚丙交酯（PLA）是一种非常重要的生物医用材料,由于它在体内可降解、无毒、安全,在临床上得到了广泛的应用.为了适应更多、更广的医学应用,要求对聚丙交酯的降解速度、力学性能等进行调节控制,或者要求改善PLA的亲水性、生物相容性、细胞亲和性等等,为此合成了一系列PLA的共聚物,并对其性能进行了研究.本文对上述领域的研究进展进行了综述,结合了作者常年来在PLA共聚物的合成与性能方面的研究,分成四大类进行阐述：（1）丙交酯与其它内酯类的共聚;（2）丙交酯与聚乙二醇类大分子的共聚;（3）丙交酯与带有功能基团单体的共聚;（4）丙交酯与其它天然材料的共聚,并简要地叙述其在医学领域应用的前景.     

表面改性聚丙烯的血液相容性研究进展

聚丙烯具有价格低廉、无毒、易于加工等优点,使其在许多领域得到广泛的应用。但是聚丙烯自身有较强的疏水性,与血液相接触时,血浆蛋白会在材料表面大量吸附,诱发血小板的粘附和聚集,从而造成凝血和溶血的发生。在生物医用材料的应用过程中,血液相容性是限制材料能否长期应用的关键因素。本文综述了表面改性法提高聚丙烯血液相容性的研究现状、表面改性方法和常用的大分子单体,并分析了当前聚丙烯表面改性研究存在的问题,展望了具有良好血液相容性聚丙烯的发展前景。     

生物可降解聚酯用作蛋白质药物控释载体

聚乳酸PLA及乳酸与羟基乙酸的共聚物PLGA,由于其良好的生物相容性以及生物降解性,可用作蛋白质类药物控释体系的载体材料,同时可延长蛋白质药物的释放.本文综述了几种生物相容性聚酯及其衍生物以及它们的形成方法:(1)在PLGA的分子链中引入亲水性的含醚键的分子如PEO、PEG,来提高聚合物的亲水性,形成PLGA嵌段共聚物;(2)将细胞可接受的片段或多肽固定在聚合物支架表面,来增强PLGA与细胞间的粘附力,得到靶向的PLGA衍生物;(3)改变PLGA载体内的酸性环境,提高蛋白质药物在载体中的稳定性,发展了支化聚酯PVA-g-PLGA,并得到均速的药物释放.以上这些方法所得到的聚酯及其衍生物,均可作为蛋白质类药物安全、可靠的载体材料.     

新型聚原酸酯共聚物的合成及性能研究

以二聚甘油为原料,经过酯交换及氨基脱保护反应合成了一种两端含氨基的环状原酸酯新单体。该单体与辛二酸/十二烷二酸活性酯缩聚得到两种新的疏水性聚原酸酯共聚物POEAd-1和POEAd-2,其数均分子量分别由凝胶渗透色谱(GPC)测得为1.24×104及1.81×104,分散度(PDI)分别为1.59及1.93。热失重分析法证实POEAd-1和POEAd-2具有较高的热稳定性能,其起始降解温度分别可达198.5℃及202.5℃。溶血试验和MTT细胞毒性试验表明,POEAd-1和POEAd-2均具有良好生物相容性,作为一种潜在的生物医用材料,在药物缓控释领域将具有广阔的应用前景。     

乙烯吡咯烷酮对PET薄膜的表面接枝改性

利用低温等离子体和UV诱导技术,制备具有较高生物相容性和亲水性的聚对苯二甲酸乙二醇酯(PET)-聚乙烯吡咯烷酮(PNVP)复合膜。利用衰减全反射傅里叶红外光谱(ATR-FTIR)、X射线光电子能谱(XPS)、原子力显微镜(AFM)对PET-PNVP复合膜表面的结构形态进行了系统表征,对影响接枝度的因素如引发剂浓度、UV辐射时间、单体浓度也做了系统分析。润湿性分析结果表明,接枝PNVP的PET膜表面亲水性得到了有效改善。体外血液相容性实验表明PET-PNVP复合膜具有较好的血液相容性。噻唑蓝比色法(MTT法)细胞毒性实验表明,PETPNVP复合膜没有细胞毒性。     

基于多巴胺自聚合及肝素固定改善钛的血液相容性

利用多巴胺自聚合及肝素固定的方法对纯钛进行表面修饰, 以改善其血液相容性. 采用水接触角测量、 X射线光电子能谱(XPS)和甲苯胺蓝法(TBO)等方法对所修饰的材料进行了表征. 采用溶血实验检测了材料的溶血性能, 并结合活化部分凝血活酶时间(APTT)测试和血小板黏附实验对所修饰材料的血液相容性进行了评价. 结果表明, 多巴胺能够在钛表面实现自聚合, 肝素可以共价接枝在聚多巴胺层上, 经肝素修饰后的材料的表面亲水性显著提高, 而且具有较低的溶血率, APTT时间显著延长, 血小板的黏附数量和被激活程度也显著降低. 因此, 纯钛经多巴胺自聚合以及肝素接枝修饰后的血液相容性得到了显著改善, 有望成为具有抗凝血功能的新型心血管植入材料.     

单糖类化合物改性聚乳酸的研究进展

聚乳酸（PLA）作为一种性能良好的生物可降解材料,在生物医用高分子等方面有着广泛的应用。单糖类小分子对多肽、蛋白质等具有较好的亲和性,对组织细胞也有较好的相容性。为了改善PLA的亲水性、细胞相容性等性能,利用单糖类化合物改性聚乳酸日益受到关注。按照单糖种类的不同,本文综述了近年来各类单糖及其衍生物等改性聚乳酸的研究进展...     

316L钢表面纳米银镀层的制备、性质及血液相容性

采用恒电位电沉积方法在316L不锈钢表面沉积银纳米镀层, 并将钢板置于全氟硅烷溶液中浸泡, 通过动态凝血实验、 抗凝血时间测定、 血小板黏附实验、 溶血实验和蛋白吸附实验等手段, 测试材料的血液相容性. 结果表明, 通过上述方法可明显改善316L不锈钢的血液相容性, 而抗凝血性能、 溶血率及纤维蛋白吸附量不亚于裸钢板. 与316L裸不锈钢相比, 银镀膜全氟硅烷浸泡316L不锈钢具有良好的血液相容性, 是一种比较理想的冠状动脉支架材料, 具有良好的应用前景.     

聚乳酸两亲性共聚物的研究进展

聚乳酸是一种具有良好的生物相容性和可降解性高分子材料,也是被美国食品和药品管理局(FDA)批准的生物医用材料.但它本身的疏水性使其在医用方面受到限制.为克服其缺陷,人们对聚乳酸做了大量改性修饰的工作以提高亲水性,如将其与各种亲水性聚合物进行聚合制得不同结构类型的两亲性共聚物.本文中我们对聚乳酸两亲性共聚物的研究进展做了综述,并讨论了它的应用现状及前景.     

无规共聚物自组装球形胶束表面亲水性的耗散粒子动力学模拟

建立了含不同亲疏水粒子比的双亲性无规共聚物粗粒化模型. 采用耗散粒子动力学方法模拟了两亲性无规共聚物选择性溶剂自组装球形胶束表面的亲水性能. 模拟结果表明, 无规共聚物在选择性溶剂中自组装得到实心球形胶束, 球形胶束表面的亲水性与聚合物链亲水粒子含量、溶剂的选择性有关. 随着聚合物链所含亲水粒子增加, 球形胶束表面的亲水性增强. 球形胶束表面的亲水性随着疏水粒子与溶剂粒子间的排斥参数增大而增强, 模拟结果与实验结论一致. 该模拟方法给出的胶束微结构信息可以为双亲无规共聚物分子设计及自组装双亲胶束制备提供一定的理论指导.     

Anti-biofouling properties of comblike block copolymers with amphiphilic side chains

Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surface chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed.     

Aqueous Self‐Assembly of Purely Hydrophilic Block Copolymers into Giant Vesicles

Self‐assembly of macromolecules is fundamental to life itself, and historically, these systems have been primitively mimicked by the development of amphiphilic systems, driven by the hydrophobic effect. Herein, we demonstrate that self‐assembly of purely hydrophilic systems can be readily achieved with similar ease and success. We have synthesized double hydrophilic block copolymers from polysaccharides and poly(ethylene oxide) or poly(sarcosine) to yield high molar mass diblock copolymers through oxime chemistry. These hydrophilic materials can easily assemble into nanosized (<500 nm) and microsized (>5 μm) polymeric vesicles depending on concentration and diblock composition. Because of the solely hydrophilic nature of these materials, we expect them to be extraordinarily water permeable systems that would be well suited for use as cellular mimics.     

Development of lauroyl sulfated chitosan for enhancing hemocompatibility of chitosan

Chitosan (CS) has received much attention as a functional biopolymer especially in pharmaceutical applications, but has serious limitations owing to its poor hemo-compatibility property. Present paper focuses on the chemical modification of CS in order to enhance hemocompatibility. Amphiphilic derivative (lauroyl sulfated chitosan, LSCS) was prepared by the inclusion of sulfo group (hydrophilic) and lauroyl group (hydrophobic) to CS backbone and particles were prepared by an ionic-gellation approach. Modification was confirmed by FTIR, NMR and zeta potential measurements and the microparticles were evaluated for its particle size, swelling properties and thermal behaviour. Blood compatibility studies like hemolysis, RBC, WBC, platelet aggregation studies, blood clotting time, protein adsorption and C3 protein depletion assay were carried out for these polymers using standard techniques and cytotoxicity studies were performed to understand its applicability. Negatively charged (-6.06 mV) LSCS submicroparticles (886 nm) were prepared in this study. Blood compatibility studies demonstrated that the amphiphilic modification improved the hemocompatibility of CS. RBC aggregation and hemolysis induced by CS were significantly reduced by this modification. Further amphiphilic modification was effective in reducing the protein adsorption on CS. LSCS derivatives were found to be non-toxic in L929 cell lines. From these studies, it appears that LSCS is a hemocompatible version of CS.     

Polymer dispersions as intermediate state during the synthesis of specialty polymers

Heterophase polymerization in combination with ceric ion redox initiation offers some unique features with respect to the preparation of block copolymers and block copolymer particles. Various kinds of amphiphilic multi-block copolymers as well as electrosterically or sterically stabilized particles are easy accessible. A special feature of these particles is that they may consists of two different hydrophilic blocks and thus, leading to particles with a structured hydrophilic shell. The amphiphilic multiblock copolymers are used to form a new class of polymer dispersions by self-organization so-called polymeric colloidal complexes. In general, the particles of these complexes are structured and exhibit very often multiple morphologies. This principle of formation of polymer colloids is an easy way to prepare particles with an unusual morphology such as Janus-type particles.     

Secondary globular structure of copolymers containing amphiphilic and hydrophilic units: Computer simulation analysis

The coil-globule transition in copolymers composed of amphiphilic and hydrophilic monomer units has been studied by the computer simulation technique. It has been shown that the structure of globules formed in such systems substantially depends on the rate at which the solvent quality worsens. The globule resulting from slow cooling is cylindrical, and its core contains a large amount of hydrophilic groups. The globule formed upon rapid cooling takes the helical conformation, in which all hydrophilic groups are displaced to the periphery. One helix turn of such globules contains 3–5 units. In both cases, the backbone of the polymer chain forms a typical zigzag-shaped structure with an average angle between neighboring bond vectors of about 60°. This fact implies that globules of copolymers consisting of amphiphilic and hydrophilic units comprise secondary structure components.     

Amphiphilic Polymethyloxazoline–Polyethyleneimine Copolymers: Interaction with Lipid Bilayer and Antibacterial Properties

Polycations, mimicking activity of antibacterial peptides, belong to an important class of molecules investigated as a support or as an alternative to antibiotics. In this work, studies of modified linear amphiphilic statistical polymethyloxazoline (PMOX) and polyethyleneimine copolymers (PMOX_PEI) series are presented. Variation of PEI content in the structure results in controllable changes of polymeric aggregates zeta potential. The structure with the highest positive charge shows the best antimicrobial activity, well visible in tests against model Gram‐positive and Gram‐negative bacteria, fungi, and mycobacterium strains. The polymer toxicity is evaluated with MTT and hemolysis assay as a reference. Quartz crystal microbalance (QCM‐D) is used to investigate interaction between polycations and a model lipid membrane. Polymer activity correlates well with molecular structure, showing that amphiphilic component is altering polymer behavior in contact with the lipid bilayer.     

Core-Corona Micelles Formed by Self-Assembly of Random Copolymer and Homopolymer Mixtures: Dissipative Particle Dynamics Simulations

Dissipative particle dynamics simulation was applied to investigate the cooperative aggregation of amphiphilic random copolymer and homopolymer mixtures in selective solvents. The amphiphilic random copolymers were set to contain more hydrophilic segments. The effects of the contents of homopolymers, the chain length of amphiphilic random copolymers, the interaction parameters, as well as the simulation time, on the cooperative aggregation were systematically studied with dissipative particle dynamics simulation method. The results showed that core-corona micelles could be formed with the addition of homopolymers, where the homopolymers accumulate at the core and the amphiphilic random copolymers as the corona. This work demonstrated that the morphology and the size of the micelles could be tuned by the controlled addition of homopolymers in the process of self-assembly.     

Physical deposition behavior of charged amphiphilic diblock copolymers: Effect of charge distribution and electric field

Coarse-grained molecular dynamics simulations are used to investigate physical deposition behavior of charged amphiphlic diblock copolymers. The effects of solvent selectivity, charge distribution in amphiphlic diblock copolymers, and electric field strength on deposition conformations are studied qualitatively. Flat amphiphilic bilayers, which consist of hydrophilic monolayer and hydrophobic brush, are formed by physical deposition of charged amphiphlic diblock copolymers in nonselective solvents. For physically deposited amphiphlic diblock copolymers in selective solvents, amphiphilic bilayers consist of disc-shaped hydrophilic monolayers and hydrophobic nanospheres are found. This study sheds light on the formation of various amphiphlic diblock copolymer deposition conformations in different solvents and interaction mechanism of different components. Furthermore, the evolution of physical deposition process of charged amphiphlic diblock copolymers layer offers new insight to the controlling of amphiphilic bilayer thickness, hydrophobic nanosphere size, and interface property of depositional amphiphlic diblock copolymers.