Highly sensitive NADH detection by utilising an aluminium hydroxide/iron hydroxide/MWCNTs nanocomposite film-modified electrode

Glassy carbon electrode (GCE) modified with aluminium hydroxide/iron hydroxide/multi-walled carbon nanotubes (AH/IH/MWCNTs) composites has been prepared by a simple method and applied for dihydro-nicotinamide adenine dinucleotide (NADH) detection. AH/IH can not only accelerate electron transfer but also electrostatically interact with the phosphate groups of NADH through iron hydroxide to improve the sensitivity of the sensor. Meanwhile, MWCNTs served as a bonding agent to provide a built-in conductor, which resulted in boosted electron transfer at the interface. Compared with the GCE, MWCNTs–GCE, and AH/MWCNTs–GCE, the AH/IH/MWCNTs–GCE exhibited an extraordinary electrocatalytic response towards NADH, with a wide linear concentration range from 0.5 to 220 μM with a low-detection limit of 0.30 μM, at a comparatively low potential (+0.15 V versus Ag/AgCl). Moreover, alcohol dehydrogenase was used as a model system for the design of a sensitive ethanol biosensor. The resulting biosensor exhibited an ethanol sensitivity of 9 μA/mM, a concentration range of 20–400 μM, and a detection limit of 5 μM. These results demonstrate the potential of the AH/IH/MWCNTs nanocomposite film for biosensors in combination with NADH-producing enzymes.