Editors' Choice—An Enzymatic Electrode Integrated with Alcohol Dehydrogenase and Chloranil in Liquid-Crystalline Cubic Phases on Carbon Nanotubes for Sensitive Amperometric Detection of NADH and Ethanol

Abstract

It’s highly desired to simultaneously immobilize enzymes and their electron mediators on electrode surface to fabricate integrated enzymatic electrodes for constructing enzyme-based bioelectrochemical devices. Herein, a facile and efficient immobilizing method has been developed using liquid-crystalline lipidic cubic phases (LCPs) coated on single-walled carbon nanotubes (SWCNTs) films as hosting matrix. To demonstrate this, an integrated enzymatic electrode has been developed by co-hosting NAD+-dependent alcohol dehydrogenase (ADH) and the NADH-oxidizing electrocatalyst chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone,TCBQ) into LCPs on CNTs for NADH detection and ethanol biosensing. In this study, TCBQ shows excellent electrocatalytic activity toward NADH electro-oxidation at a low overpotential of ca. 0.13 V (vs. Ag/AgCl) and the integrated enzymatic electrode displays fast response to ethanol oxidation. Under the optimal conditions, the built ethanol biosensor exhibits a wide linear dynamic range from 0.2 to 13 mM, low detection limit of 0.05 mM (S/N = 3), high sensitivity of 0.5188 μA mM−1, and high stability. Furthermore, the developed ethanol biosensor has been used to detect ethanol content in complex real samples including human blood, beer, red wine, and Chinese liquor with satisfactory results, suggesting its potential applications in analytical and biomedical measurements.