Three-Dimensional Sulfite Oxidase Bioanodes Based on Graphene Functionalized Carbon Paper for Sulfite/O₂ Biofuel Cells

Abstract

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Recent advances in surface chemistry of electrodes to promote direct enzymatic bioelectrocatalysis

“…Integral membrane proteins can directly exchange electrons with the electrode when incorporated in hydrophobic CNF networks [30]. Carbon surfaces can also be modified through deposition of polyelectrolyte as thin films [31]. Further, diazonium salt reduction is the method of choice to graft different functions on the carbon surface to drive specific interactions with regions of enzymes involved in DET [32][33][34].…”

Direct Electrochemical Enzyme Electron Transfer on Electrodes Modified by Self-Assembled Molecular Monolayers

“…The redox active centers of protein/enzymes in DET can be roughly categorized into two major groups: metal-based (iron, copper and molybdenum centers etc.) [20,[69][70][71] and non-metal-based (e.g., flavin adenine dinucleotide (FAD) and pyrrolo-quinoline quinone (PQQ)) centers [44,72,73]. Most, although not all, DET-capable enzymes harbor multiple redox centers, with internal ET relays via heme groups, copper clusters, or Fe-S clusters, which shuttle electrons between the electrode surface and the catalytic cofactors [45,74,75].…”

“…In this section, we overview recent studies where SAMs have been used in DET-type electrocatalysis and discuss how to obtain favorable orientations using versatile SAMs, as well as how to tune the interactions between the redox protein/enzyme and the SAM-modified electrodes. Redox proteins/enzymes which can be immobilized in well-defined orientations on SAM-modified supports are illustrated in Figure 2 [4,15,19,32,64,67,70,[76][77][78][79][80][81]. We shall overview and discuss some selected examples from each of these enzyme classes in Sections 3.1-3.3.…”

“…Although the crystallographic structure of cSOx shows that the distance between the catalytic Mo domain and the cyt b 5 domain is more than 32 Å, rapid internal ET in DET-type bioelectrocatalysis is still observed [126], effected by a conformational change on the electrode surface via the flexible tether. This "on-off" switch enables cyt b 5 to be either adjacent or remote from the Mo cofactor [70,127] in a gated ET mode, which is quite different from the rigidly bound ET relays in the FDH and GDH enzymes, but similar to the CDH operational mode.…”

Anode-Driven Controlled Release of Cathodic Fuel via pH Response for Smart Enzymatic Biofuel Cell

“…Enzymatic biofuel cells (EBFCs) can convert bioenergy from biochemical reactions directly to electricity and have been widely employed in self-powered biosensors, wearable devices, and implantable power sources (Chen et al, 2019b;Katz and MacVittie, 2013;Miyake et al, 2011;Wu et al, 2017;Xiao et al, 2019). To date, great efforts have been devoted to improving the performance of the EBFC (Fritea et al, 2019;Hickey et al, 2013;Tang et al, 2019). However, a vast majority of them suffered from the long-term coexistence of both anodic and cathodic fuels, which may be prone to interactive interference and the insufficient utilization of biofuels.…”