Quinone-Modified Surfaces for Enhanced Enzyme-Electrode Interactions in Pyrroloquinoline-Quinone-Dependent Glucose Dehydrogenase Anodes

An approach for enhancing the enzyme-electrode interface reactions with pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (GDH) is described in this study. Modification of carbonaceous electrodes with ubiquinone or its functional analogues (1,2- and 1,4-benzoquinones) that have the appropriate redox potential to provide a driving force for an electron transfer to occur, along with fast electron-transfer rate through these molecules, creates an electron sink on the electrode surface that can pull electrons from the cofactor, increasing the electron-transfer rate and generating higher current densities. Several important parameters are experimentally evaluated and/or calculated using density functional theory. Among the quinones investigated, 1,4-benzoquinone has the greatest influence on the PQQ-dependent GDH anodes, yielding 5.1-fold higher current densities on single-walled, and 3.3-fold on multi-walled carbon nanotube papers in comparison to unmodified PQQ-dependent GDH anodes.