Synthesis and characterization of glucose oxidase–core/shell magnetic nanoparticle complexes into chitosan bead

The goal of this study was to improve the activity and stability of glucose oxidase (GOD) immobilized on Co-B/SiO2 nanoparticles (NPs) entrapped in chitosan beads. The Co-B/SiO2 NPs were prepared from a silica shell-coated Co-B core using the Stöber method. GOD was covalently immobilized on the surface of Co-B/SiO2/NH2 NPs using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) as an activating agent. The optimal conditions for immobilization of GOD onto chitosan bead (IGCB) were a 1.2 wt% of chitosan solution, and 2.0 wt% of sodium tripolyphosphate (TPP). KM and Vmax were determined to be 60.7 mM and 43.5 μM/min for free GODs (FG), 15.2 mM and 4.8 μM/min for immobilized GODs (IG), and 51.2 mM and 5.0 μM/min for IGCB, respectively. After being entrapped into the chitosan beads, the GOD exhibited improved storage and operation stability. The IG and IGCB retained 48% and 64% of their initial activity after 7 reuses, respectively.