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.