Abstract
Sol-gel-derived biocompatible titanium oxide-cerium oxide (TiO2-CeO2) nanocomposite film was deposited onto indium tin oxide (ITO)-coated glass substrate by the dip-coating method. This nanobiocomposite film has been characterized using x-ray diffraction, Fourier transform infrared, atomic force microscope, and electrochemical techniques, respectively. The particle size of the TiO2-CeO2 nanobiocomposite film was found to be 23 nm. The urea biosensor fabricated by immobilizing mixed enzyme [urease (Urs) and glutamate dehydrogenase (GLDH)] on this nanobiocomposite showed a response time of 10 s, sensitivity as 0.9165 mu Acm(-2) mM(-1), detection limit of 0.166 mu M, and negligible effect due to interferants uric acid, cholesterol, glucose, and ascorbic acid. The value of Michaelis-Menten constant (K-m) estimated using Lineweaver-Burke plot as 4.8 mM indicated enhancement in the affinity and/or activity of enzyme attached to their nanobiocomposite. This bioelectrode retained 95% of enzyme activity after 6 months at 4 degrees C.