Immobilization of ?-galactosidase on concanavalin A modified silica-coated titanium dioxide nanocomposite and its interaction with monovalent and divalent cations

In this report, we describe a bioaffinity based immobilization protocol of beta-galactosidase on silica-coated titanium dioxide nanocomposite modified using concanavalin A. The prepared nanobiocatalyst displayed a phenomenally high yield of immobilization (221.7 %). The nanocomposite was characterized using electron dispersive spectroscopic analysis, scanning and transmission electron microscopy, raman and X-ray diffraction studies. The as-synthesized nanobiocatalyst showed high stability at a wide range of temperatures and pH. Meanwhile, the immobilized enzyme retained about 87 % activity after 10 successive uses, and the immobilized enzyme maintained 92 % activity after 2 months of storage. The ability of different cations to enhance enzyme activity was in the order Mg2+> K+> Na+> Ca2+. Furthermore, UV-visible spectroscopy was performed to determine structural changes in enzymes after interaction with cations. The activation of beta-galactosidase in the presence of cations can be controlled by adjusting their concentration which might have a good potential to be used in the dairy industry. This study was aimed to fabricate a stable and robust nanobiocatalyst that can be used for the manufacture of nanobiosensor with enhanced efficiency for the production of lactose free dairy products.