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 (Rct) at MIPCPE than NIPCPE. Under optimized conditions, calibration curve was obtained with a linearity range of 0.5 µM to 100 µM and the limit of detection was 0.1 µM. 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.
Graphene is well known for a variety of sensing applications due to its unique charge transport properties and ultra-thinness. Here we report, interfacing of electrochemically reduced graphene oxide (ERGO) with the polymer of erichrome black-T (PEBT) as a sensing platform for the simultaneous voltammetric determination of epinephrine (EP), uric acid (UA) and folic acid (FA). The reduction of graphene oxide (GO) and the polymerization of EBT was enabled using cyclic voltammetry (CV). Electrochemical impedance spectroscopy (EIS) and CV have been probed to study the electron transfer kinetics of the modified electrodes. An enhanced sensitivity towards the EP, UA and FA electrochemical oxidation has been observed after the modification of GCE with PEBT/ERGO. The sensor is able to detect simultaneously EP, UA and FA in their mixture at well-defined peak potential resolution. The proposed method allowed for the determination of EP, UA and FA in the presence of other interfering species with the limit of detection of 0.4 μM, 1 μM and 4.0 μM respectively. The fabricated PEBT/ERGO/GCE successfully used for the simultaneous determination of the analytes in blood sera samples with acceptable recovery rates.
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