Voltammetric Determination of Uric Acid Based on Molecularly Imprinted Polymer Modified Carbon Paste Electrode

Molecularly imprinted polymer (MIP) for uric acid (UA) was synthesized by thermal polymerization using acrylic acid (AA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross linker and 2,2-azobis(2-isobutyro) nitrile (AIBN) as initiator. The noncovalent interactions involved in four possible conformations of pre-polymer complex were computationally studied by density functional theory. The hydrogen bond formation between UA and AA was confirmed by Fourier transform infrared (FTIR) spectrum of the MIP before extraction of UA. After extraction of the template, the molecularly imprinted polymer based carbon paste electrode (MIPCPE) was fabricated under optimized conditions. A significant enhancement in the electrocatalytic oxidation of UA was found at MIPCPE. The electrochemical behavior of sensor was investigated by cyclic voltammetry (CV) and differential pulse adsorptive stripping voltammetry (DPAdSV). The electrochemical impedance spectroscopy (EIS) studies revealed less charge transfer resistance (R-ct) at MIPCPE than NIPCPE. Under optimized conditions, calibration curve was obtained with a linearity range of 0.5 mu M to 100 mu M and the limit of detection was 0.1 mu M. The sensor showed good selectivity towards UA in the presence of interferents and was successfully applied for the determination of UA in spiked serum samples.