Preparation and Release Properties of Sol-Gel Encapsulated Proteins

A glycoprotein, bovine serum albumin (BSA) was used as a model compound for encapsulation in a sol-gel matrix. Dried gels were ground into powders and meshed to achieve particle sizes less than 250 μm. The products were washed with phosphate buffer. Capillary electrophoresis was used to evaluate the encapsulation efficiency and the kinetic properties of protein release. Several parameters, including the pH and composition of the background electrolyte, were investigated in an effort to eliminate the matrix effect from the determination of release kinetics. Complete separation of the silica matrix from BSA was using phosphate buffer, an applied voltage of 15 kV, and detection at 278 nm. Kinetic studies indicated that most of the BSA was released in the first 5 h. The rate of BSA release gradually decreased, and some BSA after 25 h. These results indicated that dilute potassium phosphate buffer could accelerate protein release, but this was not observed for the concentrations greater than 50 mM. We believe the developed method has potential utility in other systems for in vitro matrix dissolution and drug release studies.