Protein-loaded poly(epsilon-caprolactone) microparticles III. Entrapment of superoxide dismutase by the (water-in-oil)-in water solvent evaporation method

This work investigated some process parameters involved in the entrapment of superoxide dismutase (model protein) in poly(epsilon-caprolactone) microparticles by a multiple emulsion solvent evaporation method. In optimal operating conditions, the particles were smooth and spherical (mean diameter 8.66 +/- 0.18 mu m) with entrapment efficiency and retained biological activity of 68 +/- 2% and 8.48 +/- 1.07% (n = 3), respectively. This dramatic activity loss was ascribed to the deleterious effect of the polymer solvent. The use of alpha-cyclodextrin decreased the entrapment efficiency and retained biological activity. These two parameters were not considerably influenced by the freeze-drying. Moreover, thermal analysis showed that superoxide dismutase did not form a true solution with the polymer and an increase in the polymer crystallization temperature after the entrapment process.