Synthesis of magnetic/silica nanoparticles with a core of magnetic clusters and their application for the immobilization of His-tagged enzymes

We synthesized magnetic/silica nanoparticles with a core/shell structure. The average diameter of the spherical particles was approximately 100 nm, and the average thickness of the silica shell was 20 nm. Due to the core of the magnetic clusters, the particles exhibited strong magnetization ( 21 emu/g). To immobilize His-tagged lipase, copper complexes with three different ligands were anchored to the surfaces of the particles. Up to 70% of the initial activity was obtained after three uses. Differences in the enzymatic activity and ligand-dependent reusability are discussed.