ABSTRACT
Objective To prepare thermosensitive chitosan (CTS) hydrogels containing astragalus polysaccharides (APS)/CTS microshperes (MS), and evaluate its physicochemical properties. Methods The APS/CTS MS (APS-MS) were prepared by spray drying method, and characterized by Scanning Electron Microscopy (SEM) and Laser Granularity Analyzer. Depending on the gelation temperature and gelating time, thermosensitive CTS hydrogels (HG) containing APS-MS (APS-MS-HG) were optimized by signal factor experiments, and the morphological characteristics were observed by SEM. In vitro release behaviors of APS-MS, hydrogels containing APS (APS-HG) and APS-MS-HG in pH 6.8 phosphate buffer were evaluated by dialysis tube method. Results The APS-MS were well dispersed with nearly spherical shapes and slightly wrinkled surfaces. The surface weighted mean D[3,2] of APS-MS was 8.078μm. The optimal APS-MS-HG, APS-MS-HG J, contained 3.012% APS-MS which were agitated with a magnetic stirrer for 3h. Observed by SEM, APS-MS were stayed spherical and dispersed unevenly in HG J, but the porous structure of HG J was disappeared in APS-MS-HG J. The release of APS from APS-MS-HG J was without initial burst release, and the cumulative amount of APS was about 74.75% after 36h. Conclusion Suppressing the phenomenon of sudden release at the first stage of delivery, APS-MS-HG J holds great promise for topical applications as a sustained-release nasal delivery system.