Covalent binding of α-chymotrypsin on the magnetic nanogels covered by amino groups

A new aminated carrier—magnetic nanogels covered by amino groups, was obtained by Hoffman degradation of polyacrylamide-coated Fe₃O₄ nanoparticles prepared by photochemical polymerization. α-Chymotrypsin (CT) was covalently bound to the magnetic nanogels by use of 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide and N-hydroxysuccinimide at room temperature. Immobilization time, pH value of the reaction mixture and proportion of CT to the magnetic nanogels were investigated to obtain the optimum condition for CT immobilization. The maximal specific activity of the bound CT was determined to be 0.93 U/(mg min), 59.3% of free counterpart. The maximal binding capacity was measured to be 102 mg enzyme/g nanogel. Furthermore, the bound CT exhibited good thermal stability, storage stability and reusability.