Non-enzymatic sensing of uric acid using a carbon nanotube ionic-liquid paste electrode modified with poly(beta-cyclodextrin)

We describe a nonenzymatic electrochemical sensor for uric acid. It is based on a carbon nanotube ionic-liquid paste electrode modified with poly(beta-cyclodextrin) that was prepared in-situ by electropolymerization. The functionalized multi-walled carbon nanotubes and the surface morphology of the modified electrodes were characterized by transmission electronic microscopy and scanning electron microscopy. The electrochemical response of uric acid was studied by cyclic voltammetry and linear sweep voltammetry. The effects of scan rate, pH value, electropolymerization cycles and accumulation time were also studied. Under optimized experimental conditions and at a working voltage of 500 mV vs. Ag/AgCl (3 M KCl), response to uric acid is linear in the 0.6 to 400 mu Ie and in the 0.4 to 1 mIe concentration ranges, and the detection limit is 0.3 mu Ie (at an S/N of 3). The electrode was successfully applied to the detection of uric acid in (spiked) human urine samples.