Nanostructured nickel oxide film for application to fish freshness biosensor

Xanthine oxidase (XOx) has been physisorbed onto nanostructured nickel oxide (n-NiO, ∼41 nm), electrophoretically deposited onto indium-tin-oxide (ITO) glass substrate using poly-ethylene glycol via co-precipitation. The electrochemical response studies of the XOx/n-NiO/ITO bioelectrode show linear response in the xanthine concentration range as 10–200 μM (R2 = 0.9989), sensitivity as 0.6214 μA/μM cm2, detection limit as 2.989 μM, standard deviation as 0.6192 μA, response time of 15 s with the stability of 100 days. The observed low value (0.0306 mM) Michaelis–Menten constant (Km) indicates high affinity of XOx towards xanthine.