Enzyme decorated dendritic bimetallic nanocomposite biosensor for detection of HCHO

In recent times, bi- and tri-metallic nanocomposites are being extensively studied to improve the catalytic surface and sensitivity of detection. In this study, we designed a formaldehyde dehydrogenase decorated Cys-AuPd-ErGO nanocomposite with fern like AuPd dendrites deposited on reduced graphene oxide (ErGO) on screen printed electrode (SPE) for determination of NADH and successfully demonstrated its application for detection of HCHO. This biosensor exhibited direct electron transfer by lowering the oxidation potential of NADH from +0.63 V to 0.32 V vs Ag/AgCl, avoiding usage of electron mediators. The sensor LOD was 0.3 μM HCHO with excellent sensitivity of 70 μA/μM/cm2 and linear detection range between 1 μM and 100 μM during chronoamperometric studies at applied over potential of +0.35 V vs Ag/AgCl. The sensor was tested for its performance in simulated HCHO adulterated samples of fish and milk, and appreciable recoveries (88–104%) at tested concentrations indicated good sensor performance. It was also validated against conventional method of HPLC with highly acceptable correlation coefficient of 0.99, indicating successful fabrication of a simple, “on site” disposable sensor for HCHO detection. The developed biosensor can also find wide application in quantitative measurement of NADH and analytes involved in reactions with the co-enzyme. [Display omitted] •Electrochemically deposited Bimetallic (Gold–Palladium) nano-dendrite on electrochemically reduced graphene oxide as electrocatalyst for highly sensitive detection of NADH .•Detection of NADH at lower oxidation potential (0.32 V vs Ag/AgCl) and redox mediator independent NADH oxidation.•Formaldehyde dehydrogenase decorated on electrocatalyst surface for NADH dependent detection of HCHO .•Determination of HCHO in various food samples such as fish and milk and validation using HPLC method .•Methodology supports various NADH dependent enzyme based electrochemical sensors .