Reagentless detection of uric acid based on Iron doped Zinc Oxide matrix

Iron doped ZnO thin films (ZnO:Fe) have been exploited for mediator-less biosensing application and have been realized as a potential matrix for the development of uric acid biosensor. Doping of iron in ZnO thin film tailors its redox property and electrical conductivity and a modified ZnO matrix is obtained that does not require any mediator in the solution besides bottom conducting electrode. The studies reveal that the bio-electrode based on Iron doped ZnO thin film matrix exhibits high sensitivity (298.33 μAmM^-1cm^-2) with good linearity over a wide range (0.05 mM to 1.0 mM) of uric acid concentration. A low value (0.16 mM) of Michaelis-Menten constant (Km) indicates high affinity of the immobilized uricase towards uric acid. The proposed ZnO:Fe thin film matrix based uric acid biosensor is found to exhibit excellent reproducibility, long shelf life (20 weeks) and high selectivity.