Electrochemical Detection of Dopamine and Uric Acid with Annealed Metal–Organic Framework/MXene (CuO/C/Ti₃C₂T_x) Nanosheet Composites for Neurotransmitter Sensing

Developing an efficient nonenzymatic electrochemical sensor for dopamine (DA), ascorbic acid (AA), and uric acid (UA) is crucial for addressing various health issues. Conventional sensors struggle with interference from massive AA concentrations, necessitating an advanced sensor design. To address these constraints, it is essential to design a dual-mode UA and DA sensor capable of maintaining its sensing performance, even in the presence of high AA concentrations. Hence, in this study, an MOF/MXene composite is prepared by an in situ growth approach and transforms into a highly conductive CuO/C/MXene composite for addressing the conductivity limitations of metal oxides and improving the sensing performance of the nonenzymatic electrochemical sensor. The structural integrity and compositional characterization of the synthesized and annealed composite are confirmed through XRD, Raman spectroscopy, FESEM, and EDAX, which revealed a dense distribution of CuO/C particles on MXene sheets, along with a porous octahedral structure. Furthermore, the formed CuO/C/MXene composite is coated on a glassy carbon electrode, and the electrochemical performance for DA, AA, and UA is determined by differential pulse voltammetry (DPV) and chronoamperometry (CA) techniques. It displays a broad linear detection range of DA (0.01–2960 μM), AA (0.01–46.5 mM), and UA (0.01–8.95 mM), with detection limits of 6.718 μM, 3.035 μM, and 1.747 nM, respectively. Also, the simultaneous performance of the proposed sensor for DA and UA analyses achieves a peak separation of 194 mV, even at elevated concentrations of ascorbic acid. The generated catalyst exhibits the lowest detection limit for dopamine, the broadest linear range for ascorbic acid and uric acid, and the simultaneous detection of dopamine and uric acid across a large potential range, attributable to the synergistic impact of the MXene and MOF-converted metal oxide composite. The proposed sensor shows excellent repeatability, reproducibility, stability, and selectivity with other sensing molecules and is suitable for analysis of real samples. This sensor has the potential for individuals with disabilities, particularly those with Parkinson’s disease and nephrosis, which are linked to abnormal dopamine and uric acid levels.