A Portable Microelectrochemical Sensor Based on Potentiostatic Polarization-Treated and Laser-Induced Graphene for the Simultaneous Determination of Ascorbic Acid, Dopamine, and Uric Acid

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