Effective entrapment of protein into polylactide microcapsule by solvent evaporation of W/O/W emulsion

Entrapment of bovine serum albumin into microcapsule using polylactic acid as a wall material was carried out by solvent evaporation of a W/O/W emulsi on prepared by a two-step emulsification method. Effects of the conditions ill the first step emulsification, which gave a W/O emulsion, and the conce ntrations of additives in the inner and outer aqueous phases on the entrapm ent efficiency and the morphology of the microcapsule are discussed. The en trapment efficiency of albumin decreases with increasing in the hold up of dispersion phase in the first step W/O emulsion preparation, and the concen tration of additives in the inner aqueous phase. On the other hand, by ultr asonic treatment for W/O emulsion and an increase in the concentration of a dditives in the outer aqueous phase, entrapment efficiency of the protein i ncreases. Permeation of water from the outer into the inner aqueous phase b y osmotic pressure difference, which causes the coalescence of the inner aq ueous phase droplets and a decrease in the capsule wall thickness, decrease s the entrapment efficiency. By considering these factors, almost all the a mount of albumin dissolved in the inner aqueous phase can be entrapped in t he capsule, and it is possible to control the entrapment of water soluble c ore materials in the preparation of microcapsules by the solvent evaporatio n method.