A stable glucose sensor with direct electron transfer, based on glucose dehydrogenase and chitosan hydro bonded multi-walled carbon nanotubes

Direct electron transfer (DET) glucose sensors are third-generation biosensors, which allow the enzyme to directly transfer electrons by glucose oxidation without a mediator. In previous studies, many researchers have focused on the glucose oxidase (GOx)-based DET glucose sensor; however, an efficient DET glucose sensor using flavin adenine dinucleotide (FAD)-glucose dehydrogenase (GDH) has not been developed. In the present study, we bound FAD-GDH and multi-walled carbon nanotubes (MWCNT), using chitosan (CS) compounds that support hydrogen bonding, van der Waals forces, and 3D structural adsorption. The GDH/CS-MWCNT-5 composite, which had a GDH concentration of 75 wt%, was physically adsorbed on screen-printed carbon electrodes (SPCEs), and cyclic voltammetry indicated that its oxidation and reduction peaks were at - 0.422 V and - 0.543 V (vs Ag/AgCl), respectively. In addition, the electrochemical results confirmed that the prepared GDH/CSMWCNT/SPCEs were not affected by other interfering substances or oxygen at pH of 7. The GDH/CSMWCNT/SPCEs displayed oxidation catalytic currents, which increased according to glucose concentrations across a range of 0-5.5 mM. Finally, the short-term stability of glucose, assessed for 10 days, was maintained at 80% of the GDH enzyme activity for 6 days, and it reduced to 50% of the initial activity for the remaining 4 days. Here, we illustrate the potential utility of the FAD-GDH-based DET method in continuous glucose monitoring sensors.

Automated summary

In this study, an efficient FAD-GDH-based DET glucose sensor was developed, which showed no interference from other substances or oxygen. The sensor exhibited increasing oxidation catalytic currents with different glucose concentrations and maintained high enzyme activity during short-term stability assessment.