Electrochemiluminescence enzyme biosensors for ultrasensitive determination of glucose using glucose dehydrogenase immobilized on vertical silica nanochannels

Abstract

Accurate determination of glucose in biological samples is of great significance for healthcare monitoring and medical diagnosis. Herein we reported an economical "signal-on" glucose electrochemiluminescence (ECL) enzyme biosensor for ultrasensitive detection of glucose based on vertically-ordered mesoporous silica films (VMSF) covalently modified with a monolayer of glucose dehydrogenase (GDH). In the presence of glucose, β-nicotinamide adenine dinucleotide sodium salt (NAD+)-dependent GDH on the surface of VMSF catalyzes the oxidation of glucose and β-nicotinamide adenine dinucleotide (NADH) reduced from NAD+ is generated concomitantly in situ. The access of NADH to underlying electrode surface is prohibited by ultrasmall nanopores, but it can act as a co-reactant to promote the ECL intensity of Ru(bpy)32+ by the free diffusion of Ru-related species, exhibiting a unique catalytic route. By recording the ECL intensity of Ru(bpy)32+ electrostatically amplified by VMSF, the present ECL enzyme biosensor allows the ultrasensitive detection of glucose substrate with a wide linear range (10 nM to 1 mM) and a rather low limit of detection (1.5 nM). Furthermore, the developed ECL enzyme biosensor is capable of anti-fouling and accurate detection of glucose in human serum and artificial sweat without tedious preprocessing, which provides a ECL enzyme sensing platform for ultrasensitive detection of a variety of substrates of interest by simply tailoring the recognition elements.