亚稳态O/W Pickering高内相乳液模板法优控制备互通大孔生物支架

Porous polymers templated from high internal phase emulsions (polyHIPEs) have been highly desirable in cartilage tissue engineering because of their ultrahigh porosity and abundant pore surface functionality provided by colloidal particles. However, the polyHIPEs obtained in recent studies have poor hydrophilicity and interconnectivity, and the small pores limit the proliferation and migration of cartilage cells. In this proposal, high internal phase emulsions (HIPEs) stabilized by gelatin nanoparticles will be first prepared. Particle property, emulsification conditions, temperature and polymerization process will be tuned to obtain metastable HIPEs, which helps to form large droplets owing to the controlled coalescence and ripening of emulsions. Macroporous scaffolds will be subsequently obtained after polymerization. Especially, in order to illuminate the relationship between pore structure of polyHIPEs and metastable emulsion templates, behavior of particles at the interface and change of microstructure of the metastable emulsions will be investigated in situ. At last, the adhesion, proliferation, and migration of cartilage cells in polyHIPEs will be studied to illustrate the correlation of pore structures with the cell response. The outcome of this project thereby will not only provide insightful understanding in metastability mechanism, but also lead to the preparation of macroporous scaffolds for cartilage tissue engineering.

Pickering高内相乳液模板法制备的多孔聚合物（polyHIPEs）具有超高孔隙率，且包埋于孔道的胶体粒子可赋予其丰富的表面功能性，因而是理想的软骨组织工程支架。但现有的polyHIPEs亲水性和孔道连通性较差，孔径尺寸偏小，影响了软骨细胞的增殖和迁移。本项目拟采用明胶纳米颗粒稳定的O/W高内相乳液为模板，通过调节胶体粒子性质、乳化条件、实验温度及聚合反应进程等形成亚稳态乳液，利用液滴聚并和乳液熟化实现液滴粒径可控增长，随后引发聚合反应获得互通大孔生物支架。借助明胶纳米颗粒的自发荧光特性，研究胶体粒子的界面行为和亚稳态乳液微观结构的变化趋势，解析亚稳态高内相乳液模板与polyHIPEs孔道结构的关联机制。最后研究软骨细胞在polyHIPEs中的黏附、增殖和迁移，阐明细胞响应与polyHIPEs孔道结构的内在关联，为互通大孔polyHIPEs应用于软骨组织工程支架奠定理论基础。

Pickering乳液模板法制备的多孔聚合物具有超高孔隙率，且包埋于孔道的胶体粒子可赋予其丰富的表面功能性，是理想的软骨组织工程支架。但现有Pickering乳液模板法制备的生物支架孔道连通性较差，孔径尺寸偏小，不利于软骨细胞的增殖和迁移。在本研究中，我们采用明胶纳米颗粒稳定的Pickering乳液为模板，通过调节胶体粒子的表面润湿性、油相类型、聚合反应进程以及盐溶液处理等形成亚稳态乳液模板，利用液滴聚并和乳液熟化实现液滴粒径可控增长，随后引发聚合反应获得互通大孔生物支架。通过SEM、CLSM、表面接触角、流变仪等表征颗粒以及生物支架的微观结构与理化性质，并进一步优化生物支架的机械性能、抗菌和促成骨功能。首先合成具有不同润湿性的明胶纳米颗粒，并利用其作为Pickering乳液模板稳定剂。结果表明，疏水性更强的氨基化明胶纳米颗粒（AGNPs）相比于明胶纳米颗粒（GNPs）能够完全吸附于液滴表面，形成致密吸附层和更大液滴尺寸。油相类型以及负载物对Pickering乳液的微观结构和液滴尺寸影响较大，长链的以及含有更多杂质的油形成的Pickering乳液的粒径更大，并且，其油水界面的吸附层更为稀疏。通过控制连续相的聚合物和交联剂的用量可调控聚合反应进程，从而调控乳液的稳定性、液滴尺寸以及连续相网络结构强度。最后，采用明胶纳米颗粒和羟基磷灰石为共同稳定剂，通过硫酸铜盐溶液处理乳液模板，调节乳液稳定性和连续相凝胶网络结构的机械性能，并且在形成大孔结构的同时引入铜离子，赋予生物支架抗菌和促成骨双重功能。研究发现，盐溶液处理可增加生物支架大孔的数量，且浸泡时间越长，大孔数量越多。本项目所形成的方法简便、建立了亚稳态Pickering乳液模板与生物支架孔道结构的关联机制，在软骨修复，植入材料等领域具有潜在应用。