Enhancing catalytic performance of β-glucosidase via immobilization on metal ions chelated magnetic nanoparticles

• Metal ions chelated magnetic nanoparticles were successfully synthesized.
• β-Glucosidase was successfully immobilized on magnetic nanoparticles.
• The immobilized β-glucosidase showed enhanced activity and good reusability.
• The immobilized β-glucosidase was promising in application.

A novel magnetic Fe3O4 nanoparticles (MNPs) coupled with agarose (AMNPs) was synthesized using co-precipitation via alkaline condition and span-80 surfactants in organic solvent. Iminodiacetate was first attached to the MNPs through epichlorohydrin agent and then chelated with metal ions. The morphology and chemical properties of these prepared supports were characterized by scanning electron microscopy (SEM), X-ray power diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FT-IR). Among them, the Co2+-chelated AMNPs (AMNPs-ECH-IDA-Co2+) showed the second highest enzyme adsorption capacity of 1.81 mg/g particles, and achieved the largest activity recovery of 117% per protein gram in immobilization of β-glucosidase (BGL). The Michaelis constant (Km) and Vmax of the immobilized BGL were 0.904 mM and 0.057 μmol/min, respectively, and its activation energy was much lower than the free form. Moreover, the immobilized enzyme exhibited enhanced thermostability and operational stability. It still retained more than 90% of its initial activity after being operated for 15 successive batches. This study demonstrates that the immobilized β-glucosidase has a good prospect in industrial applications.