Control of Size and Morphology of Gelatin Microspheres

Gelatin microspheres with different particle size and surface morphology were obtained through an emulsification-coacervation method in water-in-oil (W/O) emulsions. The effect of preparation parameters on the size and morphology of the gelatin microspheres was investigated, and the influence of post-treatment, including washing solvent and freeze-drying, on the surface morphology was also studied. The results showed that spherical microspheres, without aggregation phenomena and with a very smooth and uniform surface, are formed during the cross-linking process. The particle size of the gelatin microspheres increased with increasing concentration of the gelatin solution, emulsifying time, and W/O phase volume ratio; however, the particle size of the gelatin microspheres decreased with increasing concentration of the emulsifier and stirring rate. During the post-treatment process, the surface of the gelatin microspheres collapsed when dehydrated by acetone; the surface morphologies of microspheres were smoother when dehydrated by acetone/water solution with a volume ratio of 5:1 and acetone in sequence. When the obtained smooth gelatin microspheres were soaked in deionized water for 24 h and then treated by freeze-drying method for 12 h, microspheres with porous structure were obtained.