关键词: 硅烷化, 氨基磁性粒子, 固定化酶, 木瓜蛋白酶

Abstract: Magnetite nanoparticles were prepared by coprecipitation of Fe²⁺ and Fe³⁺ with NH₄OH,and then,silica was coated on the surface of the magnetite nanoparticles to form hydrophilic,well-distributed and well-dispersed magnetic silica nanospheres.Amino-silane was covalently coupled to the surface of the magnetic silica nanospheres and activated by glutaraldehyde.The immobilization of papain on the particles was studied,including optimization of immobilizing procedures,analysis of the immobilizing enzyme properties and its kinetics parameters.Results showed that immobilized enzyme has its optimizing temperature and pH at 70℃ and 6.8,respectively.Its Km was 34.48 mg/mL,and the enzyme activity reached 46.5%.It was proved that the amino-silane treated magnetic silica nanospheres could enhance the thermo stability,the pH endurance and the operation time of the enzyme compared to free enzyme.

Key words: silanization, amino-coated microspheres, immobilized enzyme, papain