Preparation of gelatin spherical microparticles in aqueous polymer suspension

Gelatin spherical microparticles were prepared by suspending a 20 wt% aqueous solution of gelatin in a 10 wt% aqueous solution of polyvinylpyrrolidone. Gelatin was used either without modification, or it was extracted with water or ammonium hydroxide. Suspending was carried out at 60°C. The particle size decreased considerably when the extracted gelatin was used, or when ammonium hydroxide was added to the suspension medium. Increasing the stirring intensity decreased the particle size and also the stability of the particles. The particles were stabilized by cooling and crosslinking with formaldehyde and separated from the suspension medium by washing with methanol. The resulting particles were dried of ethyl acetate. Five samples of the gelatin microparticles were prepared, the diameters of which varied from 0.5 to 15 μm in dry state.