Glad assisted synthesis of NiO nanorods for realization of enzymatic reagentless urea biosensor

• NiO nanorods (Nr-NiO) synthesized under glancing angle deposition (GLAD) configuration in RF sputtering.
• NiO nanorods (Nr-NiO) based urea biosensor is fabricated.
• Nr-NiO acts as a suitable matrix due to its high catalytic activity along with the redox behavior.
• Nr-NiO catalyzes the oxidation and reduction of thiol group present at the active sites of the immobilized enzyme urease.

NiO nanorods (Nr-NiO) synthesized under glancing angle deposition (GLAD) configuration in RF sputtering have been explored for potential application in urea biosensor. Vertically aligned cone shaped NiO nanorods synthesized over ITO coated glass (Nr-NiO/ITO/Glass) exhibit enhanced electrochemical current in a reagent less buffer due to its electro-catalytic species that are based on the shuttling of electrons between Ni2+ and Ni3+ in the octahedral site. The fabricated bioelectrode (Ur/Nr-NiO/ITO/glass) after immobilization of urease (Ur) shows excellent biosensing response characteristics with a relatively high sensitivity of about 48.0 μA/(mM) and a good linearity over a wide range (0.83–16.65 Mm) of urea concentration with the long shelf life of about 20 weeks. The low value of the Michaelis–Menten constant (Km=0.47 mM) indicates the high affinity of immobilized urease (Ur) towards the analyte (urea). The high electro-catalytic activity, along with the redox behavior of Nr-NiO, makes it an efficient matrix for the realization of a reagent less urea biosensor.