Immobilization of proteins in microspheres of biodegradable polyacryldextran

Macromolecules were immobilized by an emulsion polymerization technique in biodegradable microspheres of polyacryldextran, prepared by copolymerizing bisacrylamide with acryldextran. Such particles can be characterized by D-T-C expressions, where D denotes the concentration of derivatized dextran, T is the total concentration of acrylic compounds in the monomeric solution, and C denotes the fraction of cross-linker. In microparticles based on dextran T40 with a D-T-C of 11-1-75, the yield of immobilized protein was greater than in polyacrylamide particles. The properties of the immobilized proteins, e.g., Km and Vmax, were retained. The heat stability of the proteins was improved so that 5--10% of carbonic anhydrase still was active after 30 min at 100 degrees. However, the leakage of proteins from the polyacryldextran particles was greater than from polyacrylamide particles.