Photoelectrochemical/fluorescent detection of NAD⁺ based on gold nanoparticles acted as ethanol dehydrogenase

A dual-signal photoelectrochemical-fluorescent (PEC-FL) sensing method was developed for the detection of nicotinamide adenine dinucleotide (NAD⁺), utilizing gold nanoparticles (AuNPs) as nanozymes. Acting as ethanol dehydrogenase mimics, AuNPs catalyzed the reduction of NAD⁺ to NADH in the presence of ethanol. The generated NADH, serving as an electron donor, was oxidized at the surface of the ITO/BiVO₄/AuNPs electrode, leading to changes in the PEC signal. Furthermore, NADH emitted fluorescence at 470 nm, enabling specific detection of NAD⁺. The method demonstrated excellent linearity for NAD⁺ concentrations ranging from 0.5 microM to 20 microM (PEC) and 2 microM-20 microM (FL). The detection limits of 0.16 microM (PEC) and 0.38 microM (FL) calculated by using 3σ/s (n = 3). Employing AuNPs as nanozymes not only addressed the challenges in NAD⁺ determination but also provided a new strategy for developing efficient detection methods applicable to other significant environmental and biological analytes.