Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, PR China.
School and Hospital of Stomatology, Perking University, Beijing 100081, PR China.
Mater Sci Eng C Mater Biol Appl. 2012 Aug 1;32(6):1407-14. doi: 10.1016/j.msec.2012.04.018. Epub 2012 Apr 21.
Poly(lactide-co-glycolide) (PLGA) copolymers are the most prevalent materials for tissue engineering applications. To mimic the real microenvironment of extracellular matrix (ECM) for cell growth, nanofibrous PLGA scaffolds are preferred. PLGA5050 (in which the molar ratio of lactidyl to glycolidyl units is 50:50), which is an utterly amorphous polymer, was first reported to be made into nanofibrous networks (fiber diameter around 500 nm) using phase separation from PLGA5050/THF solutions in this study. The concentration of polymeric solution had significant effects on fiber diameter and unit length. Nonsolvent (e.g. H2O) was unnecessary to form the PLGA5050 gel, which was critical to nanofibrosis, as if the environmental temperature for gelation occurrence was low enough (-70 °C). The physical crosslinks to stabilize the PLGA5050/THF gel were believed to be GA segments along the backbone owing to their inferior solubility in THF. The addition of H2O would cause adverse effects of liquid-liquid phase separation and nanofibrosis failure owing to the hydrophilicity of glycolidyl units. Associating with the phase separation method, particle-leaching technique was applied to fabricate three-dimensional scaffolds with macroporous and nanofibrous structures. To ensure the occurrence of nanofibrosis on macropore walls, the temperature of salt particles should be best lowed to -70 °C beforehand. Accordingly, scaffolds prepared under varied parameters exhibited different nanofiber and pore morphologies, which affected the pore size, porosity, specific surface area, water contact angle and protein adsorption ability etc. The preliminary cell (MC3T3-E1) culture confirmed the cell ingrowth into the macroporous and nanofibrous PLGA5050 scaffolds in comparison with the solely nanofibrous matrixes. This kind of bi-scaled three dimensional matrixes can be superior candidate scaffolds for tissue engineering applications.
聚（丙交酯-乙交酯）（PLGA）共聚物是组织工程应用中最常见的材料。为了模拟细胞生长的细胞外基质（ECM）的真实微环境，优选纳米纤维 PLGA 支架。在这项研究中，首次报道了具有 50:50 摩尔比的丙交酯和乙交酯单元的完全无定形聚合物 PLGA5050 通过从 PLGA5050/THF 溶液中相分离制成纳米纤维网络（纤维直径约 500nm）。聚合物溶液的浓度对纤维直径和单位长度有显著影响。不需要非溶剂（例如 H2O）形成 PLGA5050 凝胶，这对于纳米纤维化至关重要，因为凝胶发生的环境温度足够低（-70°C）。据信，稳定 PLGA5050/THF 凝胶的物理交联是由于其在 THF 中的较差溶解度而沿着主链的 GA 段。由于乙交酯单元的亲水性，添加 H2O 会导致液-液相分离和纳米纤维化失败的不利影响。结合相分离方法，应用粒子沥滤技术制备具有大孔和纳米纤维结构的三维支架。为了确保在大孔壁上发生纳米纤维化，盐颗粒的温度应最好预先降低至-70°C。因此，在不同参数下制备的支架表现出不同的纳米纤维和孔形态，这影响了孔径、孔隙率、比表面积、水接触角和蛋白质吸附能力等。初步的细胞（MC3T3-E1）培养证实，与仅纳米纤维基质相比，细胞在大孔和纳米纤维 PLGA5050 支架中向内生长。这种双尺度三维基质可以是组织工程应用的优秀候选支架。
