Uric acid detection by hydrogen peroxide independent biosensors: Novel insights and applications

Uric acid (UA) is one of the most electroactive low molecular weight compounds that can be electrochemically oxidized on the surfaces of numerous noble and non-noble electrocatalysts under applied polarization. Consequently, enzymatic determination of UA in model and real samples is complicated by possible interference between electrochemical and biochemical routes. Herein, a novel strategy for amperometric enzymatic hydrogen peroxide independent UA sensing at low concentrations ( e.g., below 50 mu M) is proposed. The UA-sensitive strategy relies on the use of screen printed electrodes modified by an electrodeposited hybrid functional sensing film comprising a non-noble electrocatalyst, a bioorganic layer containing enzyme uricase (UOx), and data acquisition enabling the biochemical transformation of UA to be distinguished from the electrochemical oxidation route. Performed selectivity test utilizing adenine, xanthine, urea, ascorbic acid, ethanol and glycerol did not reveal interferences during detection of UA. This proposed approach was tested for UA detection in model and fermentation samples. The quantitative results obtained in fermentation samples were validated through optical oxygen mini sensor studies and fluorescence-based bioassays.