Immobilization of glucose oxidase onto cobalt based on silica core/shell nanoparticles as carrier

Co-B/SiO ₂/NH ₂ magnetic nanoparticles (NPs) were prepared from a silica shell-coated Co-B core using the Stöber method and amine-modification on the surface. Glucose oxidase (GOD) was covalently immobilized on the surface of Co-B/SiO ₂/NH ₂ NPs using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) as an activating agent. The magnetic NPs characteristics, such as the synthesis of Co-B/SiO ₂/NH ₂ NPs, effect of pH, temperature, and concentration of buffer for enzyme immobilization, were investigated. The optimal reaction conditions for immobilization were determined to be 0.1 M of phosphate buffer solution, pH 7.0, and 5°C. In the case of immobilized GOD without d-glucose and with 0.1 M of d-glucose for blocking, 22.98 U/g and 24.83 U/g of their original activity were retained after 7 reuses, respectively.