A Glucose-Responsive Enzymatic Electrode on Carbon Nanodots for Glucose Biosensor and Glucose/Air Biofuel Cell

Yue Gao,Feng Gao,Guozhi Wu

doi:10.4236/ajac.2019.109027

Abstract

In this study, an enzymatic electrode for glucose biosensing and bioanode of glucose/air biofuel cell has been fabricated by immobilizing poly (methylene green) (polyMG) for electrocatalytic NADH oxidation and NAD+-dependent glucose dehydrogenase (GDH) for oxidizing glucose on carbon nanodots (CNDs). The polyMG-CNDscomposites obtained by electro-polymerization of dye MG molecules adsorbed on CNDs display excellent electrocatalytic activity toward NADH electro-oxidation at a low overpotential of ca. -0.10 V (vs. Ag/AgCl) and the integrated enzymatic electrode shows fast response to glucose electrooxidation. Using the fabricated GDH-based enzymatic electrode, a glucose biosensor was constructed and exhibits a wide linear dynamic range from 0 to 8 mM, a low detection limit of 0.02 μM (S/N = 3), and fast response time (ca. 4 s) under the optimized conditions. The developed glucose biosensor was used to detect glucose content in human blood with satisfactory results. The fabricated GDH-based enzymatic electrode was also employed as bioanode to assembly a glucose/air biofuel cell with the laccase-CNDs/GC as the biocathode. The maximum power density delivered by the assembled glucose/air biofuel cell reaches 3.1 μW·cm-2 at a cell voltage of 0.22 V in real sample fruit juice. The present study demonstrates that potential applications of GDH-based CNDs electrode in analytical and biomedical measurements.

Highlights

It is the essential groundwork to fabricate enzymatic electrodes for constructing enzyme-based electrochemical biosensors and enzymatic biofuel cells (BFCs) [1] [2] [3] [4] [5]
An enzymatic electrode for glucose biosensing and bioanode of glucose/air biofuel cell has been fabricated by immobilizing poly for electrocatalytic NADH oxidation and NAD+-dependent glucose dehydrogenase (GDH) for oxidizing glucose on carbon nanodots (CNDs)
From Figure 2(B), we can clearly see that the peak current increases significantly with the addition of an increasing amount of NADH. These results demonstrate that the polymerized methylene green (polyMG)-CNDs composites show excellent electrocatalytic activity to NADH oxidation and could be further fabricated NAD-dependent dehydrogenase based enzymatic electrodes

Summary

Introduction

It is the essential groundwork to fabricate enzymatic electrodes for constructing enzyme-based electrochemical biosensors and enzymatic biofuel cells (BFCs) [1] [2] [3] [4] [5]. The GDH family is classified into three different types on the basis of its cofactors, nicotinamide adenine dinucleotide-dependent GDH (NAD-GDH), flavin adenine dinucleotide-dependent GDH (FAD-GDH), and pyrroloquinoline quinone-dependent GDH (PQQ-GDH) [11]-[16]. Among these enzymes, NAD-GDH is widely favored to be chosen to construct enzymatic electrode because it is insensitive to oxygen and highly specific to glucose [11]-[16]. The NAD-GDH based enzymatic electrode is allowed to improve the accuracy and selectivity of electrochemical biosensor of glucose and reduce the cross-talk of glucose/O2 BFC. Carbon-based materials have been intrigued due to the good electric conductivity and biocompatibility [16] [18] [23] [24] [25] [26]

Methods

Findings

Discussion

Conclusion