Methylene Green Electrodeposited on SWNTs-Based “Bucky” Papers for NADH and l-Malate Oxidation

Abstract

This research introduces a cavity anode design based on new single-walled nanotube (SWNTs) papers, "bucky" papers, used for the oxidation (and regeneration) of nicotinamide adenine dinucleotide (NADH) and the oxidation of l-malate. The materials designed are paper-like processed composites containing also additives: BP11 sample contains SWNTs and isopropanol (IPA); the BPMG sample contains SWNTs, IPA, and methylene green (MG). NADH/NAD(+) is the cofactor responsible for the oxidation of l-malate by malate dehydrogenase (MDH), in the Krebs' cycle. Because of the high overpotential of NADH oxidation, poly methylene green (PMG) was utilized as the electrocatalyst to produce NAD(+). The electrocatalyst was deposited on the surface of the "bucky" papers by electropolymerization by means of 10 voltammetric cycles in a range of -0.5 V and +1.3 V (vs Ag/AgCl reference electrode) at a scan rate of 5 mV/s. The catalytic performance of PMG was evaluated by chronoamperometric measurements of NADH oxidation at 0.3 V in phosphate buffer and l-malate oxidation at 0.1 V in the presence of MDH. For both "bucky" papers, the chronoamperometric curves of PMG, current vs NADH concentration, show a linear relationship demonstrating to have a first order Fick's law behavior for concentrations of NADH lower than 6 mM. The chronoamperometric curves in the presence of MDH, current against l-malate concentration, show a Michaelis-Menten behavior where no inhibition or competitive reaction are detected. Additionally, the anodic materials were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the polymerization of MG is effectively observed in the form of particles nucleation. The anodes show an excellent electrocatalytic activity toward NADH oxidation. The electrode design is feasible, reproducible, and overall stable.

Coupling of an enzymatic biofuel cell to an electrochemical cell for self-powered glucose sensing with optical readout

“…MG was deposited on the surface of the P10-SPE working electrode by electrochemical deposition in a three electrode cell, where a Pt wire and Ag/AgCl/3 M KCl were used respectively as counter and reference electrodes and the PEDOT surface of the SPE constituting the working electrode. The adsorption of MG was performed by cyclic voltammetry at a scan rate of 5 mV s −1 between −0.5 and 0.4 V (vs. Ag/AgCl/3 M KCl) in a solution containing 0.5 mM MG and 0.1 M KNO 3 dissolved in phosphate buffer pH 7.0 [15].…”

New electrode architectures based on poly(methylene green) and functionalized carbon nanotubes: Characterization and application to detection of acetaminophen and pyridoxine

“…The best way to prepare films of electroactive polymer is by electropolymerisation of the redox-active monomer, as is the case of phenazine monomers [1]. Electropolymerised films of phenazines have been extensively used in electrochemical sensors and biosensors [2], poly (methylene green) (PMG) being mostly utilized for electrocatalysis of NAD + regeneration [3][4][5], and consequently for the development of biofuel cells based on NAD + -dependent dehydrogenase enzymes [6][7][8][9][10][11].…”

“…CNT have been also used together with PMG, synergetic effects having been demonstrated in dehydrogenase-based reagentless biosensors [14], in a malate dehydrogenase "bucky" paper anode [6], in ethanol/air biofuel cells [9], and in a glucose dehydrogenase based bioanode [9].…”

Power Harvesting from Human Serum in Buckypaper-Based Enzymatic Biofuel Cell

“…In our study, the strategy of direct electrochemical communication has been successfully applied with nanostructured buckypaper composed of multi-wall CNTs (Narváez Villarrubia et al, 2011;Strack et al, 2011;Halámková et al, 2012;MacVittie and Katz, 2014). Enzymes were immobilized onto buckypaper by using a heterobifunctional cross-linker, 1-pyrenebutanoic acid succinimidyl ester (PBSE), which provides covalent binding with amino groups of protein lysine residues through the formation of amide bonds and interacts with CNTs via π-π stacking of the polyaromatic pyrenyl moieties (Strack et al, 2011).…”