3种干燥方法对壳聚糖微球支架物理性能和载药性能的影响

Effects of three drying methods on the physical properties and drug delivery in chitosan microspheres

目的研究干燥方法对壳聚糖微球支架物理性能和载药性能的影响。方法首先用凝集沉淀法制备湿润的壳聚糖微球,然后选用自然干燥法、慢速冻干法、快速冻干法进行干燥,检测微球的物理性能。最后以牛血清白蛋白(BSA)为模型药物,检测药物在壳聚糖微球中的包封率和释放曲线。结果与冻干微球比较,自然干燥微球的直径小,孔隙率低,溶胀小,降解慢。冻干温度也能够对支架的性能产生明显影响;与慢速冻干微球比较,快速冻干微球的直径更大,孔隙率更高,比表面积更大。载药实验表明自然干燥微球的包封率最低,释放速度最慢;快速冻干微球的包封率较高,释放速度最快,但存在最明显的突释效应;慢速冻干微球包封率与快速冻干微球类似,释放速度居中。结论干燥方法会影响支架的物理性能,进一步影响BSA的装载和释放。

Objective The purpose of this study is to investigate the effects of different drying methods on the physical properties and drug delivery of chitosan microspheres. Methods Three types of drying methods were utilized, including air drying and freeze drying after freezing at -20 ℃(slow cooling) and at -80 ℃(fast cooling). The physical properties of microspheres were characterized. Utilizing bovine serum albumin (BSA) as the model drug, the in-vitro release behaviors of drug-loaded beads were investigated. Results By comparing the physical properties of the different drying methods, the microspheres’ diameters, porosities, and surface area were observed to increase successively from air drying and slow cooling to fast cooling, whereas the pore size and the swelling and degradation rates varied. The drug-loading experiments revealed that the loading capacity of air-dried microspheres was the lowest and the release rate was the slowest. Although the loading capacity of fast cooling microspheres was high, an obvious burst release was observed. The loading capacity of slow cooling microspheres was similar to that of the fast cooling microspheres and the loaded BSA can be released continuously. Conclusion The results indicate that different drying methods can affect the physical properties of chitosan microspheres, which further influence drug loading and release.