Preparation of gelatin/hyaluronic acid microspheres with different morphologies for drug delivery

Gelatin/hyaluronic acid (Gel/HA) microspheres were prepared by emulsion–coagulation method using glutaraldehyde as cross-linker. The influence of treatment methods, including removing water by different concentrations of acetone/water solution and freeze drying, on surface morphology was also investigated. The in vitro release behaviors of icariin from smooth Gel/HA microspheres were also studied. The results indicated that the smooth and wrinkled Gel/HA microspheres were obtained when treated by pure acetone/water solution (volume ratio of 3:1) and pure acetone, respectively. More wrinkled microcracks could be observed when the Gel/HA microspheres were washed by pure acetone for longer time. The microspheres with porous structure were prepared when the obtained smooth Gel/HA microspheres were treated by freeze-drying method at −45 °C. The size of Gel/HA microspheres increased with increasing immersion time in distilled water and showed deeper and bigger pores after freeze-drying process. The cumulative drug release of icariin from the microspheres decreased with increasing GA content. The results of icariin release kinetics from Gel/HA microspheres indicated Fickian diffusion.