A paradoxical method for NAD+/NADH accumulation on an electrode surface using a hydrophobic ionic liquid.
In this communication, we describe a novel and facile method for the immobilization of NAD(+)/NADH on an electrode surface using a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][Tf(2)N]). By taking advantage of the insolubility of NAD(+)/NADH in hydrophobic ionic liquids, it is expected that NAD(+)/NADH can be retained on the electrode's surface. Alcohol dehydrogenase (ADH) and NAD(+)/NADH were immobilized with a gelatin hydrogel on an electrode that was modified with an electropolymerized ruthenium complex containing 5-amino-1,10-phenanthroline (pAPRu) as a mediator for NADH oxidation. The (ADH, NAD(+))/pAPRu-immobilized electrode exhibited the electrocatalytic oxidation of ethanol in [C4mim][Tf(2)N]. The obtained catalytic current in [C4mim][Tf(2)N] was comparable to that in buffer solution containing NAD(+). It was confirmed by UV-vis spectroscopy that NAD(+) did not dissolve in the [C4mim][Tf(2)N] and was retained on the electrode's surface. Furthermore, we succeeded in constructing an ethanol/O(2) biofuel cell comprised of an (ADH, NAD(+))/pAPRu anode and a bilirubin oxidase cathode using [C4mim][Tf(2)N] as an electrolyte.
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei, Tokyo 184-8588, Japan.
Miyuki
M
Masuda
Yusuke
Y
Motoyama
Jun
J
Kuwahara
Nobuhumi
N
Nakamura
Hiroyuki
H
Ohno
D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D001674:Bioelectric Energy Sources; D015374:Biosensing Techniques; D002384:Catalysis; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005780:Gelatin / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D007094:Imides / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D009243:NAD / Q000737:chemistry* / Q000378:metabolism; D010618:Phenanthrolines / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology
C569906:1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; D004800:Enzymes, Immobilized; D007093:Imidazoles; D007094:Imides; D052578:Ionic Liquids; D010618:Phenanthrolines; D009243:NAD; D000431:Ethanol; D005780:Gelatin; D000426:Alcohol Dehydrogenase; C025205:1,10-phenanthroline