Simultaneous electrochemical sensing of ascorbic acid and uric acid under biofouling conditions using nanoporous gold electrodes

Direct electrochemical sensing of biomolecules in samples with complex matrices such as human serum and blood is challenged by sensor surface biofouling resulting from the adsorption of concomitant macromolecules, particularly proteins. In this research, nanoporous gold (NPG) electrodes prepared from dealloying of a low-cost silver-gold alloy are applied as antibiofouling electrodes for the simultaneous determination of ascorbic acid (AA) and uric acid (UA). From cyclic voltammetric assays, the antibiofouling features of the fabricated NPG were interrogated in the presence of biofouling agents, fibrinogen (FN) and bovine serum albumin (BSA) proteins using ascorbic acid and uric acid as the redox probes. It was shown that the porous surface of NPG ensured a stable signal for the redox probe even in the presence of proteins found in biological samples. The antibiofouling capability of NPG is credited to the biosieving effect of the morphology of the NPG, restricting the diffusion of large proteins into gold pores while permitting access of small electroactive molecules to efficiently exchange electrons. By applying differential pulse voltammetry (DPV) under optimum conditions, the AA and UA biomolecules were simultaneously determined with limits of detection of 63.0 and 9.0 mu M, respectively. The DPV signals of AA and UA were stable on NPG in a biofouling environment and, the proposed NPG sensor was successfully applied for the simultaneous determination of AA and UA in the mimic human serum sample of fetal bovine serum (FBS).