CHARACTERIZATION AND MORPHOLOGICAL ANALYSIS OF PROTEIN-LOADED POLY(LACTIDE-CO-GLYCOLIDE) MICROPARTICLES PREPARED BY WATER-IN OIL-IN-WATER EMULSION TECHNIQUE

Poly(lactide-co-glycolide) microparticles, containing ricin toroid or fluorescein isothiocyanate-labeled bovine serum albumin were prepared by a water-in-oil-in-water emulsion solvent extraction procedure with a high encapsulation efficiency (from 60% to 94%). Three agitation methods: vortex mixing, homogenization and sonication, were used to make the first inner w/o emulsion and the second w/o/w emulsion. The effects of process parameters on structure, surface condition, particle size, core loading and in vitro release properties of the protein-loaded microparticles were studied. SDS-PAGE analysis showed that none of the agitation methods damaged the structural integrity and stability of the encapsulated protein. Confocal laser scanning microscopic analysis and in vitro studies indicated that heterogeneous microparticles provided a fast release profile with a large protein burst (62%), and homogeneous microparticles released protein slower with a much lower protein burst (7%). These properties may influence the dynamics of the antibody response.