Multi‐Enzyme Immobilized Anodes Utilizing Maltose Fuel for Biofuel Cell Applications

Abstract

Multi‐enzyme immobilized carbon‐felt electrodes are fabricated for application as a bioanode in biofuel cells to utilize both maltose and glucose as the fuel. The unique combination of three enzymes (maltase, mutarotase, and glucose oxidase) enables us to utilize maltose as the fuel for the bioanode. The new electrode based on carbon felt (CF) demonstrates a high oxidation current density of 6.5 mA cm−2 at 0.34 V vs. Ag/AgCl in a neutral phosphate buffer solution containing 0.025 mol dm−3 (≡M) maltose in a half‐cell configuration. Furthermore, we improve the bioanode performance by changing the surfactant from cetyltrimethylammonium bromide (CTAB) to Triton X‐100® (TX), which is used as a carbon nanotube (CNT) dispersant in the bioanode preparation process. A superior current density of 17 mA cm−2 at 0.34 V vs. Ag/AgCl is demonstrated with the multi‐enzyme bioanode by using TX as the CNT dispersant, owing to the good dispersion of CNTs attached to CF and the reduced deactivation and leakage of the enzymes. A maltose/O2 biofuel cell, composed of the multi‐enzyme immobilized bioanode and a biocathode based on bilirubin oxidase and mediator, delivers a maximum power density of 2.3 mW cm−2 and an open‐circuit voltage of 0.69 V in 0.2 M phosphate buffer solution containing 50 mM maltose.

Multi‐Enzyme‐Modified Bioanode Utilising Starch as a Fuel

“…0.04 mol L À 1 was selected based on our previous reports. [18] As shown in Figure 3a, the oxidation peak in the first cycle appeared at approximately 0.18 V on the CNT electrode, and the current decayed to 1.12 mA cm À 2 at 0.6 V possibly due to the inefficient activity of the enzyme reaction relay. In the tenth cycle, almost the same voltammograms were obtained for the starch-containing and starch-free solutions, indicating that the oxidation and reduction currents originated from the redox reaction of the mediator and not from starch degradation.…”

“…These monosaccharides can be easily oxidised using one particular enzyme. In contrast, disaccharides have rarely been used as biofuels [18][19][20] because of the limited number of enzymes for their direct oxidation. Using electrodes that combine several enzymes, known as multi-enzyme or enzyme-cascade bioelectrodes, [21][22][23][24][25][26][27] is an effective approach to address this issue.…”

“…We recently demonstrated a maltose bioanode for EFCs by developing a multi-enzyme bioanode system by combining three different enzymes, namely, α-glucosidase, mutarotase (MUT), and glucose oxidase. [18] Based on the previously demonstrated multi-enzyme system, [18,28] we focused on starch as a polysaccharide fuel for EFCs to extend our idea to multi-enzyme bioanodes. Starch is a α-D-glucose-containing polymer and is one of the most common edible polysaccharides.…”

Carbon Nanotubes in Biomedicine

“…Bharti et al [105] compared the role of a cationic an anionic surfactants in the synthesis and resulting properties of MWCNTs decorated with bi-metallic Pt-Pd nanoparticles. Yasujima [106] used Triton X-100 ® to disperse CNTs in a bioanode preparation process in a multienzyme immobilized carbon-felt electrode. Martinez-Paz et al [107] employed 0.015% Pluronic F68 culture medium solution to obtain a homogenous suspension of oxidized MWCNTs in order to determine the possible toxic effects in invertebrate Chironomus riparius caused by CNTs environmental dispersion.…”

Thermal Annealing‐Enhanced Bioelectrocatalysis in Membraneless Glucose/Oxygen Biofuel Cell based on Hydrophilic Carbon Fibers

“…Enzymatic biofuel cells (EBFCs) are green energy conversion devices that use oxidoreductases as catalysts to convert the chemical energy from renewable biofuels (e. g., sugars, alcohols, and organic acid) into electric energy under moderate conditions, [1][2][3][4][5][6] and have attracted tremendous interest due to their low-cost and high catalytic efficiency in contrast to the conventional fuel cells using noble-metals as catalysts. [7][8][9][10][11] In addition, the biofuels (e. g., glucose, lactate) used in EBFCs are abundant in the environment and especially endogenous to living organisms, so EBFCs are envisaged to be able to power implantable and wearable devices.…”