Anthracene-Modified Multi-Walled Carbon Nanotubes as Direct Electron Transfer Scaffolds for Enzymatic Oxygen Reduction

Abstract

The development of new methods to facilitate direct electron transfer (DET) between enzymes and electrodes is of much interest because of the desire for stable biofuel cells that produce significant amounts of power. In this study, hydroxylated multiwalled carbon nanotubes (MWCNTs) were covalently modified with anthracene groups to help orient the active sites of laccase to allow for DET. The onset of the catalytic oxygen reduction current for these biocathodes occurred near the potential of the T1 active site of laccase, and optimized biocathodes produced background-subtracted current densities up to 140 μA/cm 2 . Potentiostatic and galvanostatic stability measurements of the biocathodes revealed losses of 25% and 30%, respectively, after 24 h of constant operation. Finally, the novel biocathodes were utilized in biofuel cells employing two different anodic enzymes. A compartmentalized cell using a mediated glucose oxidase anode produced an open circuit voltage of 0.819 ( 0.022 V, a maximum power density of 56.8 ((1.8) μW/cm 2 , and a maximum current density of 205.7 ((7.8) μA/cm 2 . A compartment-less cell using a DET fructose dehydrogenase anode produced an open circuit voltage of 0.707 ( 0.005 V, a maximum power density of 34.4 ((2.7) μW/cm 2 , and a maximum current density of 201.7 ((14.4) μA/cm 2 .

Cholesterol as a Promising Alternative Energy Source: Bioelectrocatalytic Oxidation Using NAD-Dependent Cholesterol Dehydrogenase in Human Serum

“…5,15,34 Toray carbon paper electrodes were cut and coated with paraffin wax to yield an exposed geometric surface area of 1 cm 2 . Bilayer bioanodes (ChDH/C 8 -LPEI/DH/FcMe 2 -LPEI) were prepared by first casting the DH/FcMe 2 -LPEI layer.…”

“…5,[9][10][11] Metalloenzymes, such as laccases, bilirubin oxidase and peroxidase, are generally used at the cathode of EFCs allowing the bioelectrocatalytic reduction of O 2 or peroxides to H 2 O. [12][13][14][15] In addition to carbohydrates, other types of enzyme substrates have been reported as fuels such as alkanes, carboxylic acids, and other organic molecules. 1,16,17 Cholesterol, a sterol lipid, is a potential fuel for EFCs that can be oxidized to cholest-4-ene-3-one by some oxidases and dehydrogenases.…”

Biohydrogen for a New Generation of H2/O2 Biofuel Cells: A Sustainable Energy Perspective

“…[178][179][180][181][182] Following the same idea, graphite electrodes, either bare or modified by CNTs, were modified with aryl diazonium salts, [66] pyrene derivatives, [57,[183][184][185] or benzoic acid derivatives. [186] Accurate observations revealed a decrease in the hysteresis of the onset of O 2 reduction [57] related to the enzyme orientation of Sreptomyces coelicolor (Sc) LAC, which helps in the efficient bioelectrocatalysis in neutral media and in the presence of chloride.…”

“…[181] Many groups have reported LAC and BOD immobilization on CNTbased electrodes. [180,181,183,[226][227][228] Notably, Lalaoui et al electropolymerized pyrroles bearing a pyrene function on MWCNTs for LAC immobilization. [229] The electrode showed a high stability, retaining 50 % activity after one month.…”

TEMPO as a Promising Electrocatalyst for the Electrochemical Oxidation of Hydrogen Peroxide in Bioelectronic Applications

“…37 The anode was an unmodified Toray paper electrode (geometric area 1 cm 2 ) immersed in a solution of OxOx, 100 mM oxalate, and 5 mM TEMPO in an O 2 saturated 200 mM phosphate buffer at pH 5.2. The separator was a Nafion 212 membrane.…”