HAP-TiO2 nanocomposites based electrochemical sensor for selective and simultaneous detection of para-aminohippuric acid and uric acid

Abstract

Kidney diagnosis by p-aminohippuric acid (PAH) test indicates the ability of the kidney to combine benzoic acid with PAH by determination of the latter eliminated in urine or blood serum. Hippuric acid synthesis also occurs in both the liver and cortical cells of the kidney. However, the PAH test did not become popular because of the non-availability of a simple method for quick and accurate determination of the PAH at an affordable cost. Here, we report a novel electrochemical sensor based on hydroxyapatite-titanium dioxide (HAP-TiO2) nanocomposite for quantifying specific biomarkers PAH and uric acid (UA). Nanostructured HAP and TiO2 powders have been synthesized independently by microwave irradiation and hydrolysis methods respectively and the composites are prepared by mixing the appropriate amounts of HAP and TiO2 under sonication. Voltammetric studies of HAP-TiO2 modified glassy carbon electrodes exhibited improved electrocatalytic activity towards the oxidation of PAH and UA in a phosphate buffer saline (pH7.0). Under the optimized conditions, the oxidation peak currents are linearly proportional to PAH and UA concentrations over wide linear ranges of 50 nM to 5.760 mM, and the corresponding lowest detection limits are estimated to be 37 nM and 43 nM (S/N = 3). The fabricated electrode has been successfully implemented for the determination of PAH and UA in human urine samples. Performance of the device in terms of sensitivity, specificity, and linear range fulfills the requirement for screening the chosen biomarkers simultaneously making it suitable for clinical non-invasive liver and kidney diagnoses.