Abstract: In this paper, amine-functionalized superparamagnetic nanogel was obtained by Hoffman degradation of the PAM-coated Fe₃O₄ nanoparticles prepared by photochemical in situ polymerization. α-Chymotrypsin was successfully bound to the magnetic nanogel with amino groups in the presence of 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide(EDC). The immobilized enzyme was characterized by using photo correlation spectroscopy(PCS), transmission electron microscopy(TEM), X-ray diffraction(XRD) analysis, thermogravimetric-differential scanning calorimetry(TG-DSC) and Fourier transform infrared spectroscopy. Mean particle size of the immobilized enzyme was measured to be 31 nm by PCS; the binding capacity was 69 mg enzyme/g nanogel determined by TG analysis, 61 mg enzyme /g nanogel determined by standard BCA. The crystalline structure of Fe₃O₄ was affected by xenon lamp irradiation and enzyme immobilization. Magnetic content of the immobilized enzyme was as high as 88%. Specific activity of the immobilized α-chymotrypsin was 0.93 U/(min·mg), 59.3% of free form. It can be expected that the immobilized α-chymotrypsin has a potential in the fast detection and separation, as well as the reuse of immobilized enzymes.

Key words: Photochemical in situ polymerization, Immobilized enzyme, Superparamagnetic Fe₃O₄, α-Chymotrypsin