Synthesis and characterization of uniform polyepoxide micrometer sized particles by redox graft polymerization of glycidyl methacylate on oxidized polystyrene and polydivinylbenzene microspheres for enzyme immobilization

Polystyrene template microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in 2-methoxyethanol. Uniform polystyrene/poly(divinyl benzene) composite microspheres were formed by a single-step swelling process of the polystyrene template microspheres with dibutyl phthalate droplets containing divinyl benzene and benzoyl peroxide, followed by polymerization at 73 °C. Uniform poly(divinyl benzene) microspheres of higher surface area were produced by dissolution of the template polystyrene part of the former composite microspheres with methylene chloride. Hydroperoxide conjugated polystyrene and poly(divinyl benzene) microspheres were produced by controlled ozonolysis of these microspheres. Polyepoxide conjugated microspheres were then formed by redox graft polymerization of glycidyl methacylate on the hydroperoxide-conjugated microspheres. Microspheres with different properties, e.g., size, size distribution, shape, surface morphology, surface area, etc., have been prepared by changing various parameters belonging to the ozonolysis and the grafting polymerization processes, e.g., ozonolysis conditions and monomer volume. Trypsin was then covalently bound to the polyepoxide conjugated microspheres by interacting the epoxide groups of the particles with primary amino groups of the enzyme. A comparison between the enzymatic activity of the conjugated and the free trypsin was also established.