α-Chymotrypsin Immobilization on the Surface of Phase-transferred Fe₃O₄ Nanoparticles

The oil-soluble magnetic Fe₃O₄ nanoparticles with uniform size and morphology were synthesized via thermal decomposition of Fe(acac)₃ precursor. They were successfully transferred into aqueous phase through the ligand-exchange reaction with water-soluble PEG diacid molecule, forming water-soluble, stable, nontoxic, and magnetic composite with surface functional group. TEM, M-H curve, FTIR and TGA were used to characterize the as-synthesized composite and demonstrated that the nanoparticles maintained their superparamagnetism and biocompatibility. α-Chymotrypsin(α-ChT) was immobilized on the surface of the water-soluble nanoparticles. The immobilized α-ChT exhibited better thermal stability and high activity after repeated usage.