Urea biosensor based on zinc oxide/multi-walled carbon nanotubes/chitosan nanocomposite thin films

For the development of urea biosensor, (zinc oxide-chitosan) ZnO CH and multi-walled carbon nanotubes-chitosan (MWCNT-CH) nano-hybrid films have been developed on indium-tin-oxide (ITO) coated glass substrate. These films act as a bio-molecular matrix for immobilization of urease (Ur) and glutamate dehydrogenase (GLDH). Formation of this nano-hybrid film is confirmed by Fourier transform infrared spectroscopy (FTIR). Both sols are stable against agglomeration as zeta potential value is greater than 30 mV in each case. Cyclic voltammetry (CV) studies show decrease in value of current after the immobilization of urease and glutamate dehydrogenase which indicates insulating properties of urease enzyme. Lower Michaelis-Menten constant (Km) values of ZnO based biosensor (2.1 mg/dL) indicates that this bio-electrode has more enzyme affinity of urease to urea while CNTs based biosensor has better detection limit (0.2 mg/dl) with linear regression 0.998. Copyright © 2014 American Scientific Publishers.