Cobalt-doped MoS2 nanocomposite with NADH oxidase mimetic activity and its application in colorimetric biosensing of NADH

Abstract

NADH oxidase (NOX) is an oxidoreductase that catalyzes the oxidation of NADH to NAD+ with the participation of oxygen. NOX can artificially regulate metabolic processes as an important regulatory enzyme for NAD+ regeneration. In this study, cobalt-doped molybdenum sulfide (Co-MoS2) nanocomposite was prepared by hydrothermal synthesis, which exhibited NOX mimics. The catalytic mechanism of NOX mimics was studied. The NOX-like activity of Co-MoS2 is optimal at pH 4.5 and in the temperature range of 20–45℃. Further, its catalytic activity maintained almost the same after 5 cycles of repetitive addition of NADH, suggesting that Co-MoS2 nanozyme possessed significant catalytic persistence. The produced H2O2 catalyzed by Co-MoS2 can be detected by horseradish peroxidase (HRP) and 3,3′,5,5′-tetramethylbenzidine at pH4.5. Thus, interestingly, a colorimetric NADH sensor was proposed on the basis of the enzymatic cascade reaction of NADH oxidase-like conjugated with HRP. This as-established method had wide detection range (0.5–800 μM) with the detection limit of 0.25 μM NADH, capable of detecting NADH in real sample.