A NOVEL EMULSIFICATION-SOLVENT EXTRACTION TECHNIQUE FOR PRODUCTION OF PROTEIN LOADED BIODEGRADABLE MICROPARTICLES FOR VACCINE AND DRUG-DELIVERY

This paper describes the preparation of poly(lactide-co-glycolide) (PLG) microparticles containing ovalbumin (OVA) as a model antigen, using three different approaches; based on solvent evaporation/extraction techniques. These are respectively: (1) water-in oil-in water (W/O/W), (2) water-in oil-in water-in oil (W/O/W/O),and (3) water-in oil-in oil (W/O/O). The effects of process parameters on particle size, surface morphology, protein entrapment and release properties are presented. The use of methanol as the continuous phase results in a protein entrapment level of approximately 10% (w/w) in 10 mu m microparticles and the microparticles retain good spherical form. This successful use of an organic continuous phase, which is miscible with the polymer solution, offers the prospect of enhancing the protein loading capacity of resorbable polylactide microparticles and of improving the delivery of effective doses of vaccine and therapeutic proteins and peptides. Ovalbumin appears to act as a surfactant in the water-in oil-in oil method. This has implications for protein release and vaccine performance.