Self-Regulating Enzyme−Nanotube Ensemble Films and Their Application as Flexible Electrodes for Biofuel Cells

Abstract

Nanostructured carbons have been widely used for fabricating enzyme-modified electrodes due to their large specific surface area. However, because they are random aggregates of particular or tubular nanocarbons, the postmodification of enzymes to their intrananospace is generally hard to control. Here, we describe a free-standing film of carbon nanotube forest (CNTF) that can form a hybrid ensemble with enzymes through liquid-induced shrinkage. This provides in situ regulation of its intrananospace (inter-CNT pitch) to the size of enzymes and eventually serves as a highly active electrode. The CNTF ensemble with fructose dehydrogenase (FDH) showed the oxidation current density of 16 mA cm(-2) in stirred 200 mM fructose solution. The power density of a biofuel cell using the FDH-CNTF anode and the Laccase-CNTF cathode reached 1.8 mW cm(-2) (at 0.45 V) in the stirred oxygenic fructose solution, more than 80% of which could be maintained after continuous operation for 24 h. Application of the free-standing, flexible character of the enzyme-CNTF ensemble electrodes is demonstrated via their use in the patch or wound form.

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

“…One attractive study has been reported by Miyake et al for fructose oxidation. [311] A CNT forest was grown in the presence of an enzyme solution, and the network was shown to shrink to a near-hexagonal closepacked structure, with the intra-nanospace regulated by the size of the enzymes. For fructose oxidation, a current of up to 16 mA cm À2 was reached.…”

Effect of Pore Size of MgO-templated Carbon on the Direct Electrochemistry of <small>D</small>-fructose Dehydrogenase

“…For example, nanostructured carbons, such as carbon nanotubes [3][4][5][6][7] and carbon blacks, [8][9][10] and mesoporous carbons, such as carbon cryogel [11][12][13][14][15] and carbon aerogel, 16,17 have been investigated for use as enzyme electrode scaffolds. Carbon nanotubes and carbon blacks aggregate and create mesospaces suitable for enzymatic reactions.…”

Immobilization of acid phosphatase on a polyaniline/poly(acrylic acid) composite film for use as the anode of a fuel cell driven with L-ascorbic acid 2-phosphate

“…As to the development of the anode of the ASA2P fuel cell, the methods of fabricating the enzyme electrodes for amperometric biosensors and other biofuel cells can be applied, [9][10][11][12] in which the use of conducting polymers is helpful. The authors reported in a previous paper 13 that the film composed of polyaniline (PANI) and poly(acrylic acid) (PAA) showed both conductivity and electrochemical activity.…”