高孔隙率聚(乳酸—羟基乙酸)共聚物组织工程支架快速成形新工艺

提出一种新的快速成形(Rapid prototyping,RP)工艺方法,用于成形具有可设计的多级孔隙结构、贯通的大孔结构和高孔隙率的骨、软骨组织工程支架。它将基于离散/堆积原理的快速成形工艺与相分离、致孔剂浸出法两种传统工艺相结合,将致孔剂与高分子溶液混合制成悬液,由压力注射式喷头按照计算机设计的路径挤出至低温环境,冷冻固化、粘结成形并发生相分离,溶剂结晶被冷冻干燥去除后留下一级孔隙结构(10μm),致孔剂被去除后留下二级孔隙结构(10～100μm),按照RP所设计的路径可构建任意复杂外形和三级孔隙结构(100μm),且可以保证支架具有超过90%的孔隙率。此外,由于分散颗粒可以提高高分子溶液的粘度,解决连续挤出原理喷头无法成形具有高孔隙率的低分子量支架材料,降低材料对喷射/挤出手段的要求。此处将其用于成形要求降解速度快、孔隙率高的聚(乳酸-羟基乙酸)共聚物(Poly(Lactide-co-glycolide),PLGA)的软骨组织工程支架。

Novel Rapid Prototyping Method to Fabricate Poly(lactide-co-glycolide) Scaffold with High Porosity

A novel method is proposed to fabricate scaffolds with three-grade pores,high porosity and interconnected macro-pores. It is based on rapid prototyping (RP),phase separation and particulate leaching. The particulate is mixed into polymer solution homogeneously. And then the slurry is extruded into a low-temperature room as designed in the computer by a volume-actuated injecting (VAI) nozzle. Then a frozen scaffold with macro-pores more than 100 μm in diameter is obtained. Micro-pores less than 10 μm and between 10 μm and 100 μm in diameter also can be obtained by the respective removal of solvent and particulate. The porosity is higher than 90%. The concentration of polymer and particulate can influence both the porosity and viscosity of the slurry. Therefore,polymer with different molecular weight can be processed by the VAI nozzle to get a high-porosity scaffold. Several poly(Lactide-co-glycolide) (PLGA) scaffolds with low molecular weight and high porosity are fabricated for cartilage tissue engineering.