Hydrazide-functionalized poly(2-hydroxyethyl methacrylate) microspheres for immobilization of horseradish peroxidase

Nonporous cross-linked poly(2-hydroxyethyl methacrylate-co-ethylene dimetha crylate) (poly(HEMA-co-EDMA)) microspheres were prepared by dispersion poly merization of HEMA and EDMA. The polymerization was performed in toluene/2- methylpropan-1-ol in the presence of cellulose acetate butyrate as a steric stabilizer and dibenzoyl peroxide initiator. The particle size may be incr eased by decreasing the toluene/2-methylpropan-1-ol ratio and by increasing polymerization temperature. Adipohydrazide was attached to the microsphere s activated with 2,4,6-trichloro-1,3,5-triazine. After periodate oxidation of its carbohydrate moieties, horseradish peroxidase was coupled to the hyd razide-functionalized poly(HEMA-co-EDMA) microparticles up to 7.3 mu g of e nzyme/g of carrier without a significant loss of its activity. Immobilized peroxidase was found to be stable, retaining more than 97% of its initial a ctivity when stored for 23 days after the preparation.