4-Ethylphenyl Sulfate Detection by an Electrochemical Sensor Based on a MoS2 Nanosheet-Modified Molecularly Imprinted Biopolymer

One of the gut-derived uremic toxins 4-ethylphenyl sulfate (4-EPS) exhibits significantly elevated plasma levels in chronic kidney diseases and autism, and its early quantification in bodily fluids is important. Therefore, the development of rapid and sensitive technologies for 4-EPS detection is of significant importance for clinical diagnosis. In the current work, the synthesis of a molecularly imprinted biopolymer (MIBP) carrying 4-EPS specific cavities only using the biopolymer polydopamine (PDA) and molybdenum disulfide (MoS₂) nanosheets has been reported. The fabricated electrode was prepared using screen-printed carbon electrodes on a polyvinyl chloride substrate. The synthesized material was characterized using several techniques, and electrochemical studies were performed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The DPV technique for the electrochemical sensing of 4-EPS using the fabricated sensor (PDA@MoS₂-MIBP) determined a sensitivity of 0.012 μA/ng mL/cm² and a limit of detection of 30 ng/mL in a broad linear range of 1–2200 ng/mL. Also, the interferent study was performed to evaluate the selectivity of the fabricated sensor along with the control and stability study. Moreover, the performance of the sensor was evaluated in the spiked urine sample, and a comparison was made with the data obtained by ultraperformance liquid chromatography–tandem mass spectroscopy.