[Polyelectrolyte microcapsules as systems for delivery of biologically active substances]

Novel biodegradable microcapsules for delivery of biologically active substances (BAS) were prepared by layer-by-layer (LbL) adsorption of oppositely charged polyelectrolytes, namely sodium alginate (Alg) and poly-L-lysine (PLL). To immobilize these BAS, porous spherical CaCO3 microparticles were used as templates. The templates (cores) were coated with several layers of oppositely charged polyelectrolytes forming shell on a core surface. The core-shell microparticles were converted into hollow microcapsules by a core dissolution after an EDTA treatment. Mild conditions for microcapsule fabrication allow to perform an entrapment of various biomolecules while keeping their bioactivity. Biocompatibility and biodegradable capability of the polyelectrolytes give a possibility to use the microcapsules as the target delivery systems. Chymotrypsin (Chym) entrapped into the microcapsules was used as a model enzyme. The immobilized enzyme was found to keep about 86% of the activity compared to a native Chym. The obtained microcapsules were stable at an acidic medium while they could be easily decomposed by trypsin treatment at an slightly alkaline medium. Chym was shown to be active after being released from the microcapsules decomposed by trypsin treatment. Thus, the microcapsules prepared by the LbL - technique can be used for the development of new type of BAS delivery systems in humans and animals.