The Fe_3O_4-SiO_2 core-shell nanoparticles were synthesized by a modified St?ber method using Fe_3O_4 nanoparticles as the core ethyl orthosilicate(TEOS) as a precursor. Fe_3O_4-SiO_2 core-shell nanoparticles were modified with 3-Glycidyloxypropyl trimethoxysilane to obtain epoxy-functionalized Fe_3O_4-SiO_2 core-shell nanoparticles

and then carbonic anhydrase(CA) was immobilized on the carrier material. The carrier material were characterized by Fourier transform infrared spectroscopy(FTIR) and transmission electron microscope(TEM). By using p-nitrophenol acetate(p-NPA) as a substrate

an ultraviolet spectrophotometer was used to test the enzyme activity

and the performance of immobilized enzyme was characterized. The results show that

the thermal stability

storage stability and recycling performance of the immobilized enzyme are better than the free enzyme under the same conditions

and it still maintains 84.2% relative activity after 10 times of recycling.