Green construction of recyclable amino-tannic acid modified magnetic nanoparticles: Application for β-glucosidase immobilization.

The β-glucosidase (BGL) enzyme in food industry is great interest due to its role in food conversion to produce functional food products. In this study, the BGL was covalently immobilized onto amino-tannic acid modified FeO magnetic nanoparticles (ATA-FeO MNPs) as biocompatible nanoplatform by modified poly-aldehyde pullulan (PAP) as a cross-linker to enhance the ability and strength of the nanoparticle connection to the enzyme. The properties of support were subsequently characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The highest percentage of loading and immobilization yield was obtained with 0.1 mg enzyme/mL citrate buffer (pH 6, 1 M) enzyme solution, carrier solution of 10 mg ATA-FeO/3 mL citrate buffer (pH 6, 1 M), and PAP solution of 20% total reaction system volume. Optimum pH and temperature were found for free (pH 5.0 and temperature 30 °C) and immobilized (pH 6.0 and temperature 40 °C) enzyme. The immobilized BGL maintains its activity to 83% after 10 cycles. Therefore, immobilization of BGL by this method is an efficient procedure to improve the properties of enzyme.