A Portable\nMicroelectrochemical Sensor Based on Potentiostatic\nPolarization-Treated and Laser-Induced Graphene for the Simultaneous\nDetermination of Ascorbic Acid, Dopamine, and Uric Acid

Maintaining normal biomolecular levels in the human body\nplays\na crucial role in controlling various diseases. In this work, we designed\na portable microelectrochemical sensor based on laser-induced graphene\n(LIG) for the simultaneous determination of ascorbic acid (AA), dopamine\n(DA), and uric acid (UA). A simple electrode surface modification\nstrategy, potentiostatic polarization in an alkali solution, was applied\nto functionalize the LIG surface with the aim of enhancing the LIG\nelectrocatalytic activity, conductivity, and wettability. After electrochemical\npretreatment, the modified electrode displayed significantly enhanced\nelectrocatalytic activity toward AA, DA, and UA, with well-separated\ncharacteristic oxidation peaks for each analyte, thus achieving their\nsimultaneous detection without further modification by nanomaterials.\nDifferential pulse voltammetry (DPV) was applied for determining these\nthree analytes. Under optimal conditions, calibration curves were\nobtained in the ranges 10–5000 μM, 0.1–6000 μM,\nand 10–8000 nM for AA, DA, and UA, with the detection limits\n(S/N = 3) of 1.43 μM, 6.83 nM, and 1.07 nM, respectively. The\nmicroelectrochemical sensor achieved reliable and satisfactory results\nin detecting AA, DA, and UA in actual urine samples, demonstrating\nsignificant application prospects in human health monitoring and clinical\ndiagnosis.