Preparation of thermo-sensitive magnetic microspheres and their application to bioprocesses

Ultrafine magnetite particles were prepared by the co-precipitation method. Poly(styrene/N-isopropylacrylamide/methacrylic acid) latex particles containing ultrafine magnetite [magnetic P(St/NIPAM/MAA)] were prepared by two-step emulsifier-free emulsion polymerization. Most of the synthesized magnetic latex particles showed the reversible transition between flocculation and dispersion by controlling temperature, and the thermoflocculated magnetic latex particles were separated quickly in a magnetic field. Copolymerization of divinylbenzene with St at the first step enhanced the particle growth and was effective to improve magnetic separation of thermo-flocculated latex particles. Porcine trypsin was covalently immobilized onto the thermo-sensitive magnetic latex particles with high efficiency by the carbodiimide method. The immobilized trypsin showed high activity, and hence the thermo-sensitive magnetic latex particles are effective for enzyme reaction processes. (C) 1999 Elsevier Science B.V. All rights reserved.