Electrochemical modification at multiwalled carbon nanotube electrodes with Azure A for FAD-glucose dehydrogenase wiring: structural optimization to enhance catalytic activity and stability

Seiya Tsujimura (1) , Shunya Tanaka (1) , Andrew Gross (2) , Michael Holzinger (3)

1 Université de Tsukuba = University of Tsukuba
2 DCM - Département de Chimie Moléculaire
3 DCM - BioCEN - Département de Chimie Moléculaire - Bioélectrochimie pour les capteurs, l’énergie et les nanomatériaux

Electrochemical grafting is a suitable technology to design the electrode surface with new chemical functionality whilst maintaining the bulk property of the electrode. Electrochemical amine oxidation and diazonium salt reduction are some of the widely used techniques. Here, the electrochemical grafting of Azure A on multiwalled carbon nanotube (MWCNT) electrodes for the efficient wiring of FAD-dependent glucose dehydrogenase (FADGDH) is reported. The diazonium salt of Azure A is formed in-situ and subsequently grafted on the electrode surface via electrochemical reduction. The formal potential of the resultant Azure A modified electrode shifts to-0.05 V vs Ag/AgCl upon radical coupling with the MWCNT electrode. The electron transfer from FAD buried in the protein shell to the electrode via Azure A is then observed in the presence of glucose in the buffer solution. This study focused on the important effect of the CNT mass loading on Azure A loading as well as the bioelectrocatalytic activity and storage stability. It is determined that the three-dimensional porous structure of the MWCNT electrode is favorable for the immobilization of FADGDH and efficient electron transfer via the azure A functions. The optimized modified electrode with 300 µg CNT loading retains its initial activity for three days and 25% of the initial activity after 10 days. Furthermore, we show that the grafted Azure A is stably immobilized on the MWCNTs for one month and therefore the limiting factor for stability relates to enzyme leaching and/or deactivation.

Mots clés: Phenothiazine, diazonium electrochemical grafting, bioelectrocatalysis, FADGDH, mediated electron transfer, bioanode, multiwalled carbon nanotube, glucose dehydrogenase electrode

Domaines: Chimie

Seiya Tsujimura, Shunya Tanaka, Andrew Gross, Michael Holzinger. Electrochemical modification at multiwalled carbon nanotube electrodes with Azure A for FAD-glucose dehydrogenase wiring: structural optimization to enhance catalytic activity and stability. JPhys Energy, 2021, 3 (2), pp.024004. ⟨10.1088/2515-7655/abd298⟩. ⟨hal-03376384⟩