可降解聚乳酸与羟基磷灰石复合材料的研究

目的研制一种用于松质骨骨组织修复及骨折固定的可降解聚乳酸与羟基磷灰石复合材料。方法利用均匀复合技术,制备出羟基磷灰石在聚乳酸基体中呈单颗粒的复合材料;分别对羟基磷灰石、聚乳酸的组成、分子量及复合材料的形貌、结构、力学性能等进行测试表征。结果制备性能良好的PDLLA/HA复合材料。结论可降解聚乳酸与羟基磷灰石的复合材料具有组成均匀,生物力学性能可以满足临床使用要求。     

可降解聚乳酸/罗红霉素膜剂中药物体外释放性能研究

目的考察罗红霉素聚乳酸药膜的体外释药性能。方法采用紫外分光光度法测定溶液中罗红霉素的含量。测定波长为482nm。结果在不到三周的时间内,药物释放量超过80%。在最可能形成粘连的5-7d内,药物充分发挥了作用。结论该药膜对罗红霉素有一定的缓释作用,可用于防治术后粘连。     

生物可降解聚乳酸用于骨修复的发展前景和研究价值

背景:在骨修复材料中,聚乳酸及其复合材料因其优异的生物降解性、生物相容性和良好的力学性能已逐渐取代了传统的金属材料,成为研究热点之一.目的:以聚乳酸及其复合材料在骨修复领域应用为典例,阐述其生物降解机制以及调控聚乳酸降解速率的方法.方法:以聚乳酸、聚乳酸合成方法、聚乳酸及其复合材料、聚乳酸改性、生物可降解性、骨损伤修...     

纳米可降解聚乳酸-羟基乙酸尿道支架的制备及性能

背景：聚乳酸-羟基乙酸可作为尿道替代物进行组织缺损的修复。 目的：观察电纺丝法制备聚乳酸-羟基乙酸共聚物可降解尿道支架的可行性,并评价支架管的体外降解性能。 方法：采用电纺丝技术制备纳米聚乳酸-羟基乙酸共聚物(摩尔比80∶20)尿道支架管,并以戊二醛对支架进行交联、改性,将交联后支架截成长约1 cm小段并浸于尿液中进行体外降解实验。 结果与结论：支架管具有纳米结构,孔隙率约89%,孔径(32±19) µm;交联后可见纤维表面变粗糙,但纤维丝直径、孔径及孔隙率与交联前差异无显著性意义(P > 0.05),但交联后支架管力学性能显著提高。支架降解初期速度相对较快,中后期降解速度减慢,至8周时材料质量损失约50%,第10周完全崩解。材料在体内降解过程中相对分子质量的变化趋势与质量损失大体相同,降解早期相对分子质量下降相对较快,后期下降速度减慢并趋于平稳。表明采用电纺丝技术制备的纳米聚乳酸-羟基乙酸共聚物尿道支架可满足尿道组织工程支架的要求。     

生物可降解聚对二氧环己酮材料中单体残留的测定

建立聚二氧环己酮原料中单体二氧环己酮残留量的气相色谱测试方法。采用DB-624毛细管色谱柱(30.0 m×535μm×3.00μm),程序升温(146℃保持5 min,30℃/min升温至200℃,保持2 min)。载气为氮气,氢火焰离子化检测器(FID),进样口温度240℃,检测器温度250℃,分流比5:1,进样量2μL。结果显示单体在0.0239~0.1794 mg/m L范围内线性关系良好,平均回收率为100.3%,RSD为1.39,检测限浓度为0.2μg/m L,定量限浓度为0.5μg/m L。该方法简便快捷、准确度和灵敏度高。     

可降解聚对二氧环己酮材料的临床应用

背景：近年来诸多研究已经报道了聚对二氧环己酮的生物相容性、生物可吸收性和生物降解性;聚对二氧环己酮还在组织修复材料以及支架材料等医用领域有很好的应用。但聚对二氧环己酮的体内免疫反应评价及机制评价还有待于进一步研究,以更好地理解这些材料对免疫系统的作用。 目的：总结和分析聚对二氧环己酮的降解特性及其在临床应用方面的研究进展。 方法：应用计算机检索PubMed数据库(2000-01/2010-06),以“polydioxanone,Absorbable”为检索词;应用计算机检索CNKI数据库(2000-01/2010-06),以“聚对二氧环己酮”为检索词。共收集176篇关于聚对二氧环己酮临床应用的文献,中文39篇,英文137篇。排除发表时间较早,重复及类似研究,纳入25篇符合标准的文献。 结果与结论：聚对二氧环己酮是一种具有良好生物相容性、生物可吸收性和生物降解性的脂肪族聚酯。其分子链中独特的醚键,使其还具有良好的柔韧性,是理想的手术缝合线材料,同时还可以用于制造骨板和组织修复材料以及电纺成心血管支架等,在医用领域具有广泛的应用前景。     

斑块偏心率对可降解聚乳酸支架植入狭窄血管的影响

目的 研究支架在植入狭窄血管后,斑块偏心率对支架性能以及血管和斑块应力分布的影响.方法 构建支架和理想化狭窄血管模型,赋予斑块4种不同偏心率(0％、20％、40％、60％),采用有限元方法分析支架扩张至目标位移时,支架的径向回弹率和轴向缩短率、血管和斑块的应力变化情况.结果 随着斑块偏心率增加,支架的径向回弹率和轴向缩...     

表面图案化生物可降解聚膦腈制备及对成骨细胞的黏附

背景：纳/微米尺度的拓扑结构可影响细胞在基体上的黏附和增殖。 目的：改变制备条件,考察表面图案化聚(甘氨酸乙酯-丙氨酸乙酯)膦腈(PGAP)膜的表面性质对成骨细胞黏附和增殖的影响。 方法：将PGAP溶于氯仿配成不同浓度溶液,在25 ℃、20%或80%湿度下浇铸成膜。采用SEM、AFM、XRD和水接触角进行表征,通过体外培养,采用黏附、增殖和细胞形态等评价膜表面特性对成骨细胞生物学行为的影响。 结果与结论：高相对湿度环境有利于形成图案化表面,溶液浓度升高使图案化结构变得更加规整。溶液质量浓度120 g/L时,可得到一种蜂巢结构表面,但当其升至160 g/L后,反而不利于图案化表面的形成。高湿度环境下得到的膜表现出极性磷和氮原子在表面富集的现象。这些特性使表面图案化的PGAP膜更易于吸附蛋白质,从而使成骨细胞更易在其上黏附,增殖速度更快,细胞铺展状态也更好。说明溶液浓度和环境湿度是一种简便、可用于控制PGAP膜表面性质的方法,可用于对成骨细胞生物学行为的调控。     

降解材料聚乳酸－聚乙二醇生物相容性的研究

作者对国产新型生物医用可降解材料ＤＬ—聚乳酸—聚乙二醇共聚物（ＰＥＬＡ）进行了系统的生物学评价。结果表明：降解材料ＰＥＬＡ无全身毒性、无热原和细胞毒性、无溶血（溶血率小于５％）、对皮肤和眼粘膜无刺激、不引起致敬反应、对骨髓多染红细胞无影响。体内植入２８０天，材料基本降解完全，材料周围纤维囊壁厚度逐渐变薄，炎症细胞反应减轻。因此，可认为降解材料ＰＥＬＡ有良好的生物相容性。     

三维多孔支架材料PLLA/n-HA的体外生物相容性研究

目的：研究三维多孔支架材料聚乳酸/纳米羟基磷灰石(PLLA/n-HA)的体外生物相容性,探讨其作为细胞培养材料和骨组织工程支架的可行性。方法将大鼠成骨细胞接种于PLLA/n-HA复合支架上,体外共同培养后,CCK-8法检测大鼠成骨细胞增殖活性,荧光倒置显微镜、扫描电子显微镜下观察PLLA/n-HA复合支架材料表面和孔隙内细胞粘附情况。结果 CCK-8法检测显示实验组复合支架材料上细胞的增殖与空白对照组的差异无统计学意义（P>0.05）;电镜观察到细胞在复合支架材料表面和孔隙内大量黏附、生长,并且随着共培养时间的增加,材料表面的细胞数量呈几何级增长。结论三维多孔支架材料PLLA/n-HA的生物相容性较好,可望成为一种性能良好的骨组织工程支架材料。     

Biodegradable poly (lactic acid) microspheres for drug delivery systems

In connection with aim of maximizing the bio-availability of conventional drugs with minimum side-effects, new drug delivery systems (DDS) continue to attracted much attention. The controlled or sustained release of drugs represents one such approach, and in this regard report upon a study of DDS using biodegradable polymers which include poly (lactic acid) (PLA), poly (glycolic acid), and their copolymers (PLGA). Much attention is being paid to the controlled release of bio-active agents from microcapsules and microspheres made of biodegradable polymers, such as lactic acid homopolymers, as well as copolymers of glycolic acid. (11-21) Microcapsules or microspheres are injectable and able to provide pre-programmed durations of action, offering several advantages over the conventional dosage forms. This article reviews the results of a work program conducted in collaboration with a medical doctor upon DDS using biodegradable microspheres, such as PLA and PLGA.     

聚乳酸的合成与降解机理

聚乳酸是近年来获得广泛应用的生物相容性良好的生物材料。本文综述了聚乳酸在合成与降解方面研究的最新进展,分别对聚合与降解机理进行了总结与评述。     

生物可降解材料聚己内酯微球的细胞相容性体外研究

将聚己内酯制成平均粒径 5 .0 8± 0 .2 3μm的微球 ,采用流式细胞术研究经不同纯化处理的微球其浸提液对小鼠成纤维细胞凋亡及细胞周期的影响。结果表明 ,不同的纯化条件对聚己内酯微球的细胞相容性影响巨大。经充分洗涤干燥的产品在给药剂量范围内细胞相容性良好     

Oppositely Synchronized Lamellar Bending in Poly(l‐lactic acid) Versus Poly(d‐lactic acid) Blended with Poly(1,4‐butylene adipate)

Lamellar bending habits, as influenced by molecular‐chain chirality, in packing into dendritic spherulites with specific optical patterns are discussed using two model polymers of opposite chirality that are blended with a common polymer as examples: i) poly(l ‐lactic acid)/poly(butylene adipate) (PLLA/PBA) and ii) poly(d ‐lactic acid)/PBA (PDLA/PBA) blends. The bending habits in the spherulites of PLLA or PDLA blended with PBA are dictated by the chirality, specifically the counterclockwise and clockwise directions for the PLLA/PBA (50:50) and PDLA/PBA (50:50) blends, respectively. Straight lamellae in spiral lozenge crystals are packed with crystal aggregates of PLLA on top of the flat‐on lamellae plates acting as a basal plane during crystallization at T_c; spiral lozenge‐crystal frameworks are surrounded by needle‐like crystals resembling PBA crystals.

     

Biodegradable honeycomb-patterned film composed of poly(lactic acid) and dioleoylphosphatidylethanolamine

Honeycomb-patterned films have been reported to be useful for scaffolds of cell culture in tissue engineering. In the present study, we investigated a new compound, dioleoylphosphatidylethanolamine (DOPE), a naturally derived phospholipid having unsaturated fatty acid moieties, as a surfactant for fabricating honeycomb-patterned poly(d,l-lactide) (PLA) film. Only DOPE among commercially available phospholipids was useful as a surfactant, and it showed good solubility in PLA/chloroform solution and an excellent property for fabricating honeycomb-patterned film (the concentration of DOPE was from 0.2% to 20% by weight based on the weight of PLA). The pore size of the honeycomb was uniform, and all pores were interconnected with each other. The contact angle of water on the honeycomb-patterned film was affected by the amount of DOPE. Time-of-flight secondary ion mass spectrometer (TOF-SIMS) data suggested that DOPE was concentrated on the surface of the honeycomb-patterned film. To investigate cell proliferation and adhesion on the honeycomb-patterned film, NIH3T3 fibroblast cells were cultured on the film. The NIH3T3 cells adhered well on the honeycomb-patterned PLA film with DOPE (PLA-DOPE) and showed good cell proliferation compared to that on honeycomb-patterned PLA film fabricated with a copolymer (CAP) of dodecylacrylamide and omega-carboxyhexylacrylamide (PLA-CAP). These results suggest that the honeycomb-patterned PLA-DOPE can be applicable as a scaffold for cells with better profiles in comparison with PLA-CAP.     

Effects of Molecular Architecture on the Stereocomplex Crystallization in Poly(lactic acid) Blends

The crystallization behavior of two chemically identical but physically different co‐crystallizing poly(l ‐lactic acid) (PLLA)‐based blends is studied. The first set studied involves an all‐l unit polymer (PLLA) co‐crystallizing with a PDLA–miscible soft polyether–PDLA triblock copoly­mer, where d refers to the d isomer. The second set studied involves homopolymer blends of PLLA/miscible soft polyether/PDLA with compositions identical to the first set. Crystallization is performed under isothermal and non‐isothermal crystallization conditions and the crystallization kinetics, crystal perfection, and the blend morphology are investigated. It is clear that the stereocomplex crystallization is significantly slower in the triblock copolymer blends in comparison with the homopolymer blends. Furthermore, based on diffraction, spectroscopic, and thermal data, it is found that the stereocomplex crystals formed in the homopolymer blends achieve higher order and perfection, with a melting temperature 15–20 °C higher than those formed in the triblock blends.

     

Temperature-Sensitive Biodegradable Poly(ethylene glycol)

We report here that the incorporation of several disulfide bonds along poly(ethylene glycol) (PEG) gives temperature sensitivity, as well as biodegradability to PEG. To synthesize a PEG with temperature sensitivity in a physiologically important range (20–40°C), PEGs with molecular masses of 400 and 600 Da were randomly coupled by disulfide bonds. As the mol ratio of PEG (400 Da) disulfide to PEG (600 Da) disulfide increased from 40:60 to 60:40, the cloud point of the polymer aqueous solution decreased from 35°C to 27°C. The disulfide bonds between PEGs were degraded in the presence of a thiol-containing biomolecule of glutathione in a thiol-concentration-dependent manner.     

Poly(L-lysine)-GRGDS as a biomimetic surface modifier for poly(lactic acid)

The immobilization of adhesion peptide sequences (such as RGD) at the surfaces of poly(alpha-hydroxyacid)s, including poly(lactic acid) (PLA), is complicated by an absence of functional groups to support covalent attachment. We demonstrate a method to overcome this problem, by attaching the peptide to poly(L-lysine) (PLL), which immobilizes the sequence through adsorption at the poly(alpha-hydroxyacid) surface. When coated using a 0.01% w/v solution of PLL-GRGDS, bovine aortic endothelial cells seeded upon the modified PLA showed a marked increase in spreading over unmodified PLA. However, inhibition of the cell-spreading effect occurred when using higher concentrations of PLL-GRGDS, which we attribute to the PLL component. This inhibitory effect can be challenged by increasing the amount of GRGDS attached to each PLL molecule. Potentially, this is a flexible method of surface modification that can engineer many different types of tissue engineering scaffolds with a variety of biomolecules, thus allowing initial cell adhesion to be controlled.     

不同表面电荷微球改性聚乳酸表面的制备及其细胞相容性研究

采用不同的表面活性剂制备得到不同表面电荷性质的聚乳酸微球。并利用表面截留原理,将不同表面电荷性质的微球结合到聚乳酸基材表面,制备获得了不同表面电荷性质的微球改性聚乳酸表面。激光共聚焦显微镜、扫描电镜对改性表面的稳定性、表面形貌的测试结果显示,该方法成功地获得了稳定的、具有不同表面电荷性质的微球改性聚乳酸表面;软骨细胞相容性测试结果表明正电荷表面性质的微球改性聚乳酸表面较其他表面电荷性质的微球改性聚乳酸表面具有更好的细胞相容性,更能促进细胞的黏附、增殖等生长过程。