Zinc oxide-chitosan nanobiocomposite for urea sensor

Zinc oxide (ZnO)-chitosan (CH) nanobiocomposite film onto indium-tin-oxide (ITO) coated glass has been used to immobilize urease (Urs) and glutamate dehydrogenase (GLDH) for urea detection. The presence of ZnO nanoparticles in CH results in its increased surface area and enhanced electron transfer kinetics. The Urs-GLDH/CH-ZnO/ITO bioelectrode characterized using electrochemical, Fourier transform infrared, and scanning electron microscopy studies exhibit linearity of 5-100 mg/dl, detection limit of 3 mg/dl, response time of 10 s, reproducibility as 20 times, and shelf life of 3 months. The low Michaelis-Menten constant (K-m) value (4.92 mg/dl) indicates enhanced affinity of enzyme with nanobiocomposite. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2980448]