Immobilization of glucose oxidase onto a novel platform based on modified TiO2 and graphene oxide, direct electrochemistry, catalytic and photocatalytic activity.

In this work a new organic-inorganic nanocomposite has been introduced for enzyme immobilization. The composite consisting of graphene oxide (GO) and titanium oxide nanoparticles (TiO2) modified with 2, 2'-dithioxo-3, 3'-bis (3-(triethoxysilyl) propyl)-2H, 2'H-[5, 5'-bithiazolylidene]-4, 4'(3H, 3'H)-dione as Organic-Inorganic Supporting Ligand (OISL). The OISL was covalently attached to TiO2 nanoparticles and employed for obtaining a suitable solid surface to enzyme attachment. The glucose oxidase (GOD) was irreversibly loaded on the GC/GO/TiO2-OISL using consecutive cyclic voltammetry. The enzyme immobilization and the enzymatic activity were determined by electrochemical methods. The cyclic voltammogram displayed a pair of well-defined and nearly symmetric redox peaks with a formal potential of -0.465V and an apparent electron transfer rate constant of 1.74s(-1). The GO/TiO2-OISL can catalyze the electroreduction and electrooxidation of hydrogen peroxide. The GC/GO/TiO2-OISL/GOD electrode was used in the hydrogen peroxide determination. The fabricated nanobiocomposite shows dramatic photoelectrocatalytic activity which evaluated by studying the electrocatalytic activity of the fabricated electrode toward hydrogen peroxide in darkness and in the presences of light.