Polyelectrolyte assembling for protein microencapsulation

We have developed a novel microencapsulation technique based on covering micronized protein-containing aggregates with a polyelectrolyte multilayer. Here we describe the procedure of the incorporation of pancreatic proteases or ovalbumin into microparticles by layer-by-layer adsorption of oppositely charged polyelectrolytes (dextran sulfate, chitosan) on a proteinaceous core and give an account of the impact of the microencapsulation protocol on the protein release parameters. Insoluble protein-polyanion microaggregates were used as templates. Microparticles varying in the number of cycles of polyelectrolyte adsorption on protein-polyanion aggregates were examined and compared. Polyelectrolyte microparticles were shown to retain the shape and dimensions of the initial template. The microparticles were stable at pH below 5; at pH close to the pH of small intestine a protein release started. The higher the number of polyelectrolyte adsorption cycles was, the lower was the protein release rate. The microparticles obtained seem to be a promising vehicle for oral protein delivery.