Immobilization of Trametes versicolor laccase on magnetically separable mesoporous silica spheres

Magnetic mesoporous silica spheres (MSS) with large pore size were prepared by reducing Fe3+-containing mesoporous silica spheres. Laccase from Trametes versicolor was immobilized on magnetic mesoporous silica spheres through physical adsorption and covalent attachment methods. Laccase oxidizes 2,2'-azinobis(3-ethylbenzthiazolin-6-sulfonate) (ABTS) to the green cation radical (ABTS(center dot+)) as a model system; the immobilized laccase retained the activity and exhibited higher resistance to pH changes and thermal stability. The immobilized laccase obtained through covalent attachment almost has no leaching and can retain above 70% of activity after 10 consecutive operations. More interesting, the immobilized laccase can be separated quickly using an external magnetic field. Therefore, the magnetite-containing mesoporous silica spheres are a promising support for enzyme immobilization.