Novel microparticulate system made of poly(methylidene malonate 2.1.2)

Formulation of PMM 2.1.2 microparticles entrapping ovalbumin as a model pro tein was achieved by using a double emulsion solvent evaporation method. Pa rameters such as the nature of the solvent, polymer concentration and polym er molecular weight were investigated. Preparation process led to the forma tion of spherical and smooth particles with a mean diameter of 5 mum, and a n encapsulation efficiency and protein loading level of up to 16 and 2.9% w /w, respectively. After an initial burst of approximately 10%, the protein was released at a rate of less than 1% per day. This slow release kinetics of encapsulated ovalbumin in phosphate buffer indicates that most of the pr otein was encapsulated within the polymer matrix. Degradation of PMM 2.1.2 microparticles in the presence of esterases indicated that side chain hydro lysis of the polymer was the rate-determining step in bioerosion; cleavage of the ester side chain, which was further hydrolyzed to glycolic acid and ethanol, led to an acrylic acid and subsequent solubilization of the polyme r. However, slow polymer backbone solubilization after degradation was obse rved. (C) 2001 Elsevier Science Ltd. All rights reserved.