An amperometric oxalate biosensor based on sorghum oxalate oxidase bound carboxylated multiwalled carbon nanotubes-polyaniline composite film

A highly sensitive, specific and rapid electrochemical oxalate biosensor was constructed by covalently immobilizing sorghum leaf oxalate oxidase on carboxylated multiwalled carbon nanotubes and conducting polymer, polyaniline nanocomposite film electrodeposited over the surface of platinum (Pt) wire using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) chemistry. The modified electrode was characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FFIR) spectrophotometry. The optimized oxalate biosensor showed linear response range of 8.4-272 mu M with correlation coefficient of 0.93 and rapid response within Ss at a potential of 0.4 V vs Ag/AgCl. The sensitivity was approximately 0.0113 mu A/mu M with a detection limit of 3.0 mu M. Proposed oxalate biosensor was successfully applied to human urine sample. (C) 2010 Published by Elsevier B.V.