Investigation on preparation and protein release of biodegradable polymer microspheres as drug-delivery system

Among the different approaches to achieve protein delivery, the use of polymers, especially biodegraded, holds great promise. This work aimed to study the preparation and protein release of a novel drug-delivery system based on human serum albumin (HSA) encapsulated into biodegradable polymer microspheres. The microspheres containing HSA were elaborated by the solvent-extraction method based on the formation of multiple w/o/w, emulsion. The encapsulation efficiency (E,E.) of HSA was determined by the CBB method. Alginate/alginate and calcium chloride was added into an internal aqueous phase to investigate the protein loading efficiency, protein stability, and in vitro release profiles. Microspheres were characterized in terms of their morphology, size distribution, loading efficiency, and in vitro protein release. SDS-PAGE results showed that HSA kept its structural integrity during the encapsulation and release procedure. In vitro studies indicated that the microspheres with alginate added in the internal aqueous phase had a smaller extent of burst release. In conclusion, the work presents a new approach for macromolecular drugs (such as protein drugs, vaccines, and peptide drugs) delivery. (C) 2002 John Wiley Sons, Inc.