Protein-loaded poly(epsilon-caprolactone) microparticles. I. Optimization of the preparation by (water-in-oil)-in water emulsion solvent evaporation

The aim of this work was to optimize protein entrapment in pure poly(epsilo n-caprolactone) (PCL) microparticles (MP) using the (water-in-oil)-in water solvent evaporation technique and bovine serum albumin (BSA) as drug model . Therefore, the preparative variables such as polymer solvent, protein/pol ymer ratio, polymer molecular weight, internal aqueous/organic phases ratio , organic/external aqueous phase ratio, and nature of the emulsifier were e valuated on microparticle characteristics such as BSA entrapment, entrapmen t efficiency, size and morphology. The in vitro release profiles of BSA fro m such MP in two different media with or without sodium dodecyl sulphate (S DS) were investigated. In optimum conditions, smooth and spherical pure PCL MP with high encapsulation efficiency (50.29 +/- 5.01%) were prepared. The release profiles of BSA in the release media were significantly different and faster in the presence of SDS. Moreover, they exhibited a relatively lo w burst effect after 24 h (<30%) followed by a continuous release over 28 d ays. Due to PCL's numerous desirable characteristics, such MP could be an e xciting alternative for the controlled release of proteinaceous compounds.