Electrochemical sensor based on polydopamine-molecularly imprinted polymer for detection of 4-ethylphenyl sulfate "a novel gut metabolite": Fabrication, characterization, and performance evaluation in human urine

The 4-ethylphenyl sulfate (4-EPS) is considered a well-known gut microbiota derived metabolite that is involved in various human diseases and ailments. Thus, in the present work, an electrochemical sensor was developed using a polydopamine (PDA) based molecularly imprinted polymer (MIP) for the detection of 4-EPS, a gut metabolite using cyclic voltammetry (CV) for the first time. The synthesized PDA-MIP was characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques. The PDA-MIP was drop casted on the surface of screen-printed carbon electrode (SPCE) to fabricate an electrochemical sensor. The developed PDA-MIP/SPCE sensor showed a broad linear detection range of 0.1-300 ng/mL (corre-lation, R2 = 0.982) with a high sensitivity of 153.88 & mu;A (log ng/mL)-1cm � 2 and a low limit of detection (LOD) of 0.018 ng/mL. The selectivity studies were also performed against the possible interfering compounds in human urine. The reproducibility of fabricated PDA-MIP/SPCE shows relative standard deviation (RSD) of 5.34%. For demonstrating the effectiveness of the sensor, the real sample analysis was performed in human urine and it shows the good recovery range of 98.1-121.8% with a RSD of 1.35-13.93%. Therefore, the MIP based elec-trochemical sensor is economically feasible, which may propose a new diagnostic method for identifying diseases associated with the concentration of 4-EPS in other body fluids.