초록/요약

Abstract 1 The present work describes a method for the detection of NAD+ and NADH by simple preparation of the electrode by coimmobilization of diaphorase and polysiloxane viologen polymer electron mediator. The viologen polymer and diaphorase were entrapped on a glassy carbon electrode surface by drop-coated hydrophilic polyurethane. The modified electrode showed good electrocatalytic activities in NAD+ reduction and NADH oxidation. It showed a detection limit of 28 μM, a sensitivity of 0.22 nAμM-1, and a linear range from 0.2 mM to 4 mM for detecting NAD+. NADH sensing was also demonstrated. This sensing system of NAD+ was also coupled with glucose dehydrogenase to detect D-glucose. Abstract 2 Here we report a simple-prepared modified electrode for electrochemical detection of NAD+ and NADH. Propylamine viologen and diaphorase were crosslinked by poly (ethylene glycol (400) diglycidyl ether) onto printed electrode surface. By means of cyclic voltammetry and amperometry, the electrochemical characteristics of the modified electrode were described. As results shown, the modified electrode showed good electrochemical reactivity for detecting both NAD+ and NADH. Additionally, the modified electrode successfully detected NAD+ with a sensitivity of 14.8 nAμM-1 and a detection limit of 0.4 μM. The case of NADH detection showed a sensitivity of 24 nAμM-1 and a detection limit of 0.25 μM with a fast response time of 3 s (t90%). The pH profiles were also studied and for NAD+ reduction and NADH oxidation, respectively.