Spherical hydrophilic magnetic polymer (MGM) containing oxiranes was synthesized by designing the inverse suspension polymerization system in which formamide was employed as the dispersant of magnetic Fe3O4 microcrystal.Scanning electron microscopy (SEM)

FT-IR spectroscopy

X-ray diffraction (XRD)

vibrating sample magnetometer (VSM)

low temperature N2 adsorption and chemical analysis methods were used to characterize the properties of the polymer.The results showed that MGM had good spherical shape and narrow size distribution

and the particles with diameters ranging from 0.13 mm to 0.28 mm were about 91 wt%.The surface hydrophilicity of Fe3O4 microcrystal was improved by formamide dispersing treatment.The gel particles made by the copolymerization of glycidyl methacrylate and N

N′-methylene bisacrylamide could encapsule Fe3O4 microcrystal to produce colloid cores

and uniform and stable MGM microspheres were formed by the conglomeration of the colloid cores.The saturated magnetization of MGM reached 6.5 emu/g while the Fe3O4 content were 6.17%.The specific surface area

average pore diameter and pore volume and oxirane content was 117.6 m2/g

15.6 nm

0.46 cm3/g and 0.53mmol/g

respectively.Penicillin G acylase (PGA) was immobilized on MGM microspheres by the covalent coupling between the reactive oxiranes of MGM and amino groups of PGA under mild conditions.The apparent activity of the immobilized PGA reached 502 IU/g for hydrolyzing penicillin G potassium to 6-aminopenicillanic acid at 37℃.There was no agglomeration of the magnetic particles in applications .