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.     

等离子体表面技术和在有机材料改性应用中的新进展

综述了20世纪90年代以来低温等离子体表面技术及其在有机材料改性应用中的新进展。介绍阻挡放电和远等离子体处理是实现工业化和获得更好的等离子体表面改性的新方法。目前的研究更多地关注于等离子体接枝表面改性,即将不同性能的单体接枝于用等离子体处理过的材料表面获得永久性表面改性,以提高材料的粘附性、吸湿性、吸附性、导电性和生物相容性等。对低温等离子体表面改性技术的研究和应用进行了展望。     

Ti表面构建Ⅳ型胶原/肝素生物层提高细胞相容性的研究

支架表面内皮化成为最终实现支架与血液及组织长期相容的良好途径,内皮祖细胞在材料表面的集聚、生长与增殖使快速内皮化成为可能。利用静电结合作用将抗凝血药物肝素和内皮细胞基膜中重要组成的Ⅳ型胶原结合到Ti表面,使其具有良好的细胞相容性。Ti通过碱活化和硅烷化处理后,形成带正电荷的氨基表面,与有残留负电荷的肝素/Ⅳ型胶原复合物静电结合,形成生物化层。通过傅立叶红外掠射检测了材料表面特征基团的变化,通过水接触角的测定和扫描电子显微镜跟踪表面亲疏水性能以及表面形貌的变化。通过免疫荧光染色法对Ⅳ型胶原进行定性表征。结果显示仿生层构建成功,修饰后的表面较Ti表面能够粘附更多的内皮祖细胞,细胞生长与增殖较快,且细胞形态良好,细胞相容性得到明显改善。Ⅳ型胶原的引入对于心血管植入器械的表面改性有重要参考价值。     

钛表面层层组装胶原与肝素改善血液相容性的研究

为了改进钛表面的血液相容性，本实验通过电荷作用层层组装带正电的细胞外基质胶原和带负电的肝素，在钛表面形成多层仿生膜，以改善钛表面的血液相容性。钛通过氢氧化钠处理，表面形成多孔结构，并产生碱性羟基，之后将其浸泡于多聚赖氨酸溶液中，然后将材料交替浸泡于肝素和胶原中，最后一层为肝素，通过电荷吸引形成多层膜．通过傅立叶红外漫反射（FTTR）检测各步反应后表面基团的变化，通过扫描电子显微镜（SEM）观察表面形貌的变化，初步说明肝素已经结合在材料表面；血小板黏附实验直观反应组装膜有良好的血液相容性。通过本实验说明这种改性方法对于材料血液相容性的改善有一定价值。     

竹纤维/聚乳酸可降解复合材料相容界面构建进展

竹纤维/聚乳酸可降解复合材料是一种性能优越、可完全生物降解的绿色生态环保材料。在针对亲水竹纤维与疏水聚乳酸界面不相容而导致竹纤维/聚乳酸复合材料性能劣化的问题,研究者通常采用三种策略来提高其界面相容性:竹纤维改性、聚乳酸树脂改性和增容剂改性。在现有研究基础上,未来可以通过引进纳米纤维改性粒子改善复合体系的界面相容性,完善两相界面基础理论,促进更深入的界面作用及其机理研究,以推动竹纤维/聚乳酸可降解复合材料的发展。     

射频等离子体对纯钛表面的氨基化改性

采用射频辉光等离子体技术,以氮气与氨气的混合气体为气体源对纯钛进行处理。采用X射线光电子能谱对改性的样品表面成分进行分析,并讨论氨基化机理;采用表面接触角测试仪研究了处理时间、放置时间及保存方式对材料表面亲水性的影响。结果表明:经过氮气与氨气的混合气体等离子体改性后,材料表面存在氨基和氮钛化合物,处理90 min后,表面氨基含量高;改性后材料表面亲水性增加,但随放置时间的增加亲水性变差,在5 h内,改性钛片保存在氮气气氛中有利于亲水性的保持。     

丝素改性胶原膜的低温等离子体改性及体外抗凝血性研究

选用SO2、NH3、CO2三种工作气体，采用低温等离子体技术对丝素改性胶原膜进行了表面改性。运用X光电子能谱分析了材料的表面性质。材料的体外抗凝血性能由体外凝血时间——凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)作为评价标准。结果表明，SO2、CO2等离子体处理可分别在材料表面引入磺酸和酸酸基团，材料的体外抗凝血性得到很大的改善。NH3等离子体处理可以增加材料表面的氨基的数目，它对材料的抗凝血性没有贡献。     

基于等离子体技术改性纺织材料的研究进展

改性可改善纺织材料性能或赋予其新的性能.改性方法主要包括生物改性法、化学改性法和物理改性法.等离子体技术是物理改性法中的典型技术,主要基于电离产生的等离子体来实现各种改性目的.近年来,等离子体技术已成为一个非常活跃、发展迅速的研究领域,在纺织材料的表面改性中占有重要地位.相对于其他改性方法而言,等离子体技术具有化学药品使用少、污染小、可操作性强等优势.通过等离子体在材料表面的作用可实现材料改性而不影响材料的内部结构.基于等离子体技术处理纺织材料的研究主要集中在以下四个方面:(1)清洁效果;(2)改变表面形态;(3)引入自由基;(4)等离子体聚合.低温等离子体对材料的损伤较小,是目前纺织材料改性中应用较广泛的等离子体技术.通过等离子体技术的刻蚀活化、自由基改性、聚合覆膜三种途径可提升纺织材料的润湿性、耐摩擦性、生物相容性及可染色性能,还能赋予纺织材料抗菌、自清洁以及自修复等功能,从而提升纺织品的应用价值,拓展其应用范围.本文简述了等离子体技术的分类,总结了当前等离子体技术的发展现状,重点综述了等离子体技术在纺织材料领域的应用,详细阐述了基于等离子体技术对纺织纤维、织物和纤维膜进行改性的研究进展.最后,基于以上综述结果,对等离子体技术在纺织材料领域的研究前景进行了展望.     

聚氨酯人工血管的研究进展

聚氨酯由于其优良的机械性能和生物相容性而广泛应用于生物医用材料,如制作人工器官、药物释放载体及人工血管等.但是当它作为体内移植材料使用时会引起机体的炎症反应,并且与血液接触时还会引起持续的凝血和内膜增生.因此,要想将聚氨酯应用于人工血管,就要进一步提高它的生物相容性、血液相容性和细胞相容性等.目前主要是通过对聚氨酯进行本体改性、表面接枝聚合改性、等离子体处理聚氨酯表面、涂覆生物分子及结构设计等方法来提高其在体内使用时的性能.     

医用聚乳酸材料的化学改性研究进展

聚乳酸是一种常用的可生物降解的医用材料,但单纯聚乳酸并不能满足临床需要.对聚乳酸的改性工作一直都备受关注.综述了近几年聚乳酸生物降解材料的化学改性研究进展,重点论述了共聚、接枝、星型、表面改性4个方面.经改性后聚乳酸的力学性能、降解性能和亲水性能可以得到某些改善,从而更好地满足了生物医用需要.并展望了未来聚乳酸的发展.     

Effects of hydrolysis on dodecyl alcohol-modified bioactive glasses and PDLLA/modified bioactive glass composite films

In this article, mesoporous 58S and 58S bioactive glasses (BGs) were surface modified by dodecyl alcohol through esterification reaction and PDLLA/modified BGs composite films were prepared. The purpose of this study was to investigate the properties of the modified BGs particles and the PDLLA/modified BGs composite films before and after hydrolytic treatment. The modified BGs powders and composite films were treated in boiling water for 20 min to remove the dodecyl chains. After hydrolytic treatment, the modified BGs powders showed increased hydrophilicity and the FTIR analysis revealed that most dodecyl chains were removed. Furthermore, the hydrophilicity of the PDLLA/modified BGs composite films was also greatly improved. The tensile strength of the composite films after hydrolysis decreased slightly, but was still much higher than that of pure PDLLA film. In addition, bone marrow mesenchymal stem cells from dogs on the composite films after hydrolytic treatment showed the highest proliferation rate. The results suggest that hydrolytic treatment is an effective and practicable method to remove alcohol chains from surface-modified BGs and polymers/modified BG composites, which may be used for preparation of bioactive scaffolds for tissue engineering applications.     

聚乳酸涂层改善网状羟基磷灰石陶瓷支架力学性能的研究

采用有机泡沫浸渍法制备出高孔隙率的三维网状羟基磷灰石(HA)生物陶瓷支架,并采用不同浓度的聚乳酸(PDLLA)溶液涂覆网状HA支架,以达到增强补韧网化陶瓷支架的目的.通过扫描电镜观察PDLLA涂覆网状HA陶瓷支架的显微结构和测试力学强度,研究了不同浓度PDLLA溶液涂覆对网状HA支架的涂层厚度、显微结构和力学性能的影响.实验结果表明:涂覆一定量的PDLLA涂层可以显著提高网状HA生物陶瓷支架的抗压强度,同时保持网状陶瓷支架的贯通性和孔隙率.     

Formation of bone-like apatite on poly(L-lactide) to improve osteoblast-like compatibility in vitro and in vivo

The biomimetic apatite coating process was adopted to modify poly(L-lactide) (PLLA) surfaces with osteoblasts-like cell compatibility. The apatite coating was formed on the pre-hydrolyzed PLLA film and scaffold surfaces by incubating in simulated body fluid (SBF). Scanning electron microscopy and energy dispersive X-ray analyzer were utilized to characterize the composition and the structure of the apatite coating. The cytocompatibility of the modified PLLA films was investigated by testing osteoblast-like attachment, proliferation, alkaline phosphatase (ALP) activity, and cell cycle. Subsequently, the modified PLLA scaffolds were co-cultured with the osteoblasts-like in vitro and subcutaneously implanted into nude mice. The experimental results showed that the formed apatite had a nano-sized particle and matrix configuration. The surface modification of PLLA with apatite coating significantly promoted osteoblast-like compatibility. After a four-week culture in vivo, no significant inflammatory signs were observed in the implanted regions and osteoblast-like congeries with bone-like structure began to form in the scaffolds. The positive results of this study suggest a good way to produce desirable PLLA biomaterials for bone tissue engineering.     

电纺丝聚乳酸纤维支架的制备及其细胞相容性研究

静电纺丝法制备的聚(D,L-乳酸)超细纤维具有孔隙率高、孔径/结构可调、生物相容性良好等特点,已成为组织工程支架材料研究的热点。探讨了纺丝溶液浓度、流量、电压、干燥方式等影响聚(D,L-乳酸)纤维支架形貌的因素,确定了最佳工艺参数为纺丝溶液浓度为0.20g/mL,流速为0.8mL/h,电压为12kV,经真空冷冻干燥,可获得分布比较均匀,直径大多为500～900nm的聚乳酸纤维。体外细胞形貌观察表明聚(D,L-乳酸)纤维支架具有良好的细胞相容性。     

Formation of bone-like apatite on poly(L-lactide) to improve osteoblast-like compatibility in vitro and in vivo

The biomimetic apatite coating process was adopted to modify poly(L-lactide) (PLLA) surfaces with osteoblasts-like cell compatibility. The apatite coating was formed on the pre-hydrolyzed PLLA film and scaffold surfaces by incubating in simulated body fluid (SBF). Scanning electron microscopy and energy dispersive X-ray analyzer were utilized to characterize the composition and the structure of the apatite coating. The cytocompatibility of the modified PLLA films was investigated by testing osteoblast-like attachment, proliferation, alkaline phosphatase (ALP) activity, and cell cycle. Subsequently, the modified PLLA scaffolds were co-cultured with the osteoblasts-like in vitro and subcutaneously implanted into nude mice. The experimental results showed that the formed apatite had a nano-sized particle and matrix configuration. The surface modification of PLLA with apatite coating significantly promoted osteoblast-like compatibility. After a four-week culture in vivo, no significant inflammatory signs were observed in the implanted regions and osteoblast-like congeries with bone-like structure began to form in the scaffolds. The positive results of this study suggest a good way to produce desirable PLLA biomaterials for bone tissue engineering.     

Surface modified electrospun nanofibrous scaffolds for nerve tissue engineering

The development of biodegradable polymeric scaffolds with surface properties that dominate interactions between the material and biological environment is of great interest in biomedical applications. In this regard, poly-ε-caprolactone (PCL) nanofibrous scaffolds were fabricated by an electrospinning process and surface modified by a simple plasma treatment process for enhancing the Schwann cell adhesion, proliferation and interactions with nanofibers necessary for nerve tissue formation. The hydrophilicity of surface modified PCL nanofibrous scaffolds (p-PCL) was evaluated by contact angle and x-ray photoelectron spectroscopy studies. Naturally derived polymers such as collagen are frequently used for the fabrication of biocomposite PCL/collagen scaffolds, though the feasibility of procuring large amounts of natural materials for clinical applications remains a concern, along with their cost and mechanical stability. The proliferation of Schwann cells on p-PCL nanofibrous scaffolds showed a 17% increase in cell proliferation compared to those on PCL/collagen nanofibrous scaffolds after 8 days of cell culture. Schwann cells were found to attach and proliferate on surface modified PCL nanofibrous scaffolds expressing bipolar elongations, retaining their normal morphology. The results of our study showed that plasma treated PCL nanofibrous scaffolds are a cost-effective material compared to PCL/collagen scaffolds, and can potentially serve as an ideal tissue engineered scaffold, especially for peripheral nerve regeneration.     

Polysaccharide surface engineering of poly(D, L-lactic acid) via electrostatic self-assembly technique and its effects on osteoblast growth behaviours

The objective of this study was to surface modify the poly (D, L-lactic acid) (PDLLA) films and assess the effects of the modified surfaces on the functions of osteoblasts cultured in vitro. A layer-by-layer (LBL) self assembly technique, was used leading to the formation of multilayers on the PDLLA film surfaces. Chitosan (Chi) and poly (styrene sulfonate, sodium salt) (PSS) were utilized as polycation and polyanion in this study, respectively. The layer structure was investigated by using X-ray photoelectron spectroscopy (XPS) and water contact angle measurement, respectively. XPS analysis displayed the presence of chitosan on PDLLA surface. A full coverage of coating with PSS/Chi layers was achieved on the PDLLA surface only after the deposition layers of PEI/(PSS/Chi)₂. These results showed that PDLLA films could be modified with PSS/Chi pairs which may affect the biocompatibility of the modified PDLLA films. To confirm this hypothesis, cell proliferation, cell viability as well as alkaline phosphtase activity of osteoblasts on layer-by-layer modified PDLLA films as well as control samples were investigated in vitro. The proliferation of osteoblasts on modified PDLLA films was found to be greater than that on control (p < 0.05 and p < 0.01) after 1, 4 and 7 days culture, respectively. Cell viability measurement showed that the PSS/Chi modified PDLLA films have higher cell viability (p < 0.01) than control. Osteoblast differentiation function (ALP) on LBL-modified PDLLA film was found significantly higher (p < 0.01) than that of virgin PDLLA films. These data suggests that PSS/Chi pair was successfully employed to surface modify PDLLA film via a layer-by-layer technique, and enhanced its cell biocompatibility.     

Corneal epithelialisation on surface-modified hydrogel implants: artificial cornea

The objective was to investigate corneal re-epithelialisation of surface-modified polymethacrylate hydrogel implants in order to evaluate them as potential materials for an artificial cornea. Polymethacrylate hydrogels were modified with amines and then coated with different extracellular matrix proteins (collagen I, IV, laminin and fibronectin). The modified hydrogels were surgically implanted into bovine corneas maintained in a 3-D culture system for 5 days. The epithelial growth across the implant surface was evaluated using fluorescent, light and electron microscopy. Full epithelialisation was achieved on 1,4-diaminobutane-modified hydrogels after coating with collagen IV. Hydrogels modified with 1,4-diaminobutane but without further coating only showed partial re-epithelialisation. Hydrogels modified with other amines (1,2-diaminoethane or 1,3-diaminopropane) showed only partial re-epithelialisation; further coating with extracellular matrix proteins improved epithelialisation of these surfaces but did not result in complete re-epithelialisation. Evaluation of the corneas implanted with the 1,4-diaminobutane-modified hydrogels coated with collagen IV showed that the artificial corneas remain clear, integrate well and become covered by a healthy stratified epithelium. In conclusion the 1,4-diaminobutane surface-modified hydrogel coated with collagen IV supported the growth of a stable stratified epithelium. With further refinement this hydrogel has the potential to be used clinically for an artificial cornea.     

Histological study of surface modified three dimensional poly (<Emphasis Type="SmallCaps">d</Emphasis>,<Emphasis Type="SmallCaps"> l</Emphasis>-lactic acid) scaffolds with chitosan in vivo

Biocompatibility and tissue regenerating capacity are essential for biomaterials that used in tissue engineering. The aim of this study was to histologically assess the tissue reactions and bone conductivities of surface modified three dimensional (3-D) poly (d, l-lactic acid) (PDLLA) scaffolds, which were coated with chitosan via a physical entrapment method. The native PDLLA scaffold was prepared via thermally induced phrase separation technique and was characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Osteocalcin assay, a method to evaluate the bone formation potential, has shown that the osteocalcin production in chitosan-modified 3-D PDLLA scaffold group was significantly higher (p < 0.05) than that of in control. The tissue reactions and bone conductivities between surface modified PDLLA and native PDLLA scaffolds were evaluated using a rabbit radialis defect model in vivo and compared at different implantation intervals (2, 4, 8 and 12 weeks). The histological results have shown a higher bone formation potential and better biocompatibility of chitosan-modified 3-D PDLLA scaffolds as compared with the control group scaffolds.     

Fabrication and evaluation of biomimetic scaffolds by using collagen–alginate fibrillar gels for potential tissue engineering applications

Pore architecture and its stable functionality under cell culturing of three dimensional (3D) scaffolds are of great importance for tissue engineering purposes. In this study, alginate was incorporated with collagen to fabricate collagen–alginate composite scaffolds with different collagen/alginate ratios by lyophilizing the respective composite gels formed via collagen fibrillogenesis in vitro and then chemically crosslinking. The effects of alginate amount and crosslinking treatment on pore architecture, swelling behavior, enzymatic degradation and tensile property of composite scaffolds were systematically investigated. The relevant results indicated that the present strategy was simple but efficient to fabricate highly interconnected strong biomimetic 3D scaffolds with nanofibrous surface. NIH3T3 cells were used as a model cell to evaluate the cytocompatibility, attachment to the nanofibrous surface and porous architectural stability in terms of cell proliferation and infiltration within the crosslinked scaffolds. Compared with the mechanically weakest crosslinked collagen sponges, the cell-cultured composite scaffolds presented a good porous architecture, thus permitting cell proliferation on the top surface as well as infiltration into the inner part of 3D composite scaffolds. These composite scaffolds with pore size ranging from 150 to 300 μm, over 90% porosity, tuned biodegradability and water-uptake capability are promising for tissue engineering applications.