A Reagentless Biosensor for the Amperometric Determination of NADH

Abstract

A flavin analog (1) in which the isoalloxazine ring of riboflavin is linked to a pyrrole group has been synthesized and electrochemically characterized. The enzyme flavin reductase (Fre) was successfully immobilized by copolymerization of compound 1 and the amphiphilic pyrrole ammonium derivative 2. The amperometric response of the resulting poly(1-2)-Fre electrode to NADH was based on the oxidation of the enzymically reduced flavin analog 1 at ¹0.1 V (vs. SCE). The sensitivity and detection limit of the biosensor for NADH are 13.7 mA M ¹1 cm ¹2 and 0.5 mM, respectively. The new biosensor is NADH-specific since no amperometric response was observed for repeated additions of NADPH.

Otimização da preparação de eletrodo de pasta de carbono contendo riboflavina imobilizada em suporte inorgânico

“…A importância de flavinas em catálises enzimáticas tem motivado os estudos do comportamento eletroquímico de monocamadas ou agregados contendo flavinas sintéticas 9 . A flavina nucleotídeo tem a habilidade para transferir um ou dois elétrons e promover a redução de oxigênio molecular 10 . As flavinas também trabalham como coenzimas redox em muitas transformações biológicas e, conseqüen-temente, vêm sendo empregadas como mediadores redox entre o eletrodo e várias enzimas 11 .…”

Ca2+ enhanced catalytic NADH oxidation: a coupled 31P-NMR and electrochemistry study

“…However, significant overpotentials are required to oxidize this compound at bare electrode surfaces. One way to overcome this problem is the use of redox mediators and numerous molecules have been suggested for this purpose, [1][2][3][4][5][6][7][8] but so far with only limited commercial importance due to either short lifetime or modest rate constants. Furthermore, in many cases there is no detailed understanding of the involved chemical and electrochemical reactions on a molecular level, which might help to resolve the above-mentioned problems.…”