The preparation of BSA-PLLA microparticles in a batch supercritical anti-solvent process

Poly(l-lactic acid) (PLLA) microparticles loaded with a model protein (bovine serum albumin: BSA) have been prepared using a novel batch supercritical anti-solvent process. BSA-PLLA microparticles were characterized as regards their morphologies, BSA content and in vitro release profile. Scanning electron microscopy observations showed that BSA-PLLA microparticles possessed irregular and elliptical morphology with smooth surface. Fourier-transformed infrared (FTIR) assessment and differential scanning calorimetry (DSC) measurement indicated the successful encapsulations of BSA into PLLA during the process. In vitro release of BSA-PLLA microparticles showed an initial burst release of about 40% in 30 min and a prolonged release of the protein over a 24 h period at 37 °C. This work shows that our novel process can be used to efficiently encapsulate solid protein particles and get sustained-release solvent-free microparticles, without any structural alteration of the BSA protein.