A highly sensitive NADH biosensor using nitrogen doped graphene modified electrodes

The present work describes the fabrication of highly sensitive and selective β-nicotinamide adenine dinucleotide (NADH) sensor using nitrogen doped graphene (NDG). NDG modified glassy carbon electrode (GCE) exhibits strong and stable electrocatalytic response towards NADH oxidation. A substantial (253 mV) decrease in the overpotential for NADH oxidation reaction (compared to GCE) is observed at NDG/GCE. NDG was prepared using hydrothermal procedure and characterized using spectroscopy and microscopy techniques. Furthermore, amperometric responses of NDG/GCE have high sensitivity towards NADH oxidation at lower oxidation potential and minimization of surface contamination. The fabricated NADH biosensor exhibited enhanced and reproducible sensitivity of 0.16 μA/μM (S/N = 3) with a response time of < 3 s and the calculated limit of detection is 0.37 μM. A linear dynamic range from 0.5–12 μM was observed for the fabricated biosensor with a correlation coefficient (R2) of 0.99. Moreover, the biosensor exhibited strong stability after prolonged usage. The oxidation peak potential at the NDG/GCE remained unchanged even after 15 days, with minimum surface contamination. Therefore, NDG materials are found useful and promising candidates for NADH detection and are attractive for dehydrogenase based biosensor.