Cysteine-Grafted\nCu MOF/ZnO/PANI Nanocomposite for\nNonenzymatic Electrochemical Sensing of Dopamine

Electrochemical sensing has shown great promise in monitoring\nneurotransmitter\nlevels, particularly dopamine, essential for diagnosing neurological\nillnesses like Parkinson’s disease. Such techniques are easy,\ncost-effective, and extremely sensitive. The present investigation\ndiscusses the synthesis, characterization, and potential use of a\ncysteine-grafted Cu MOF/ZnO/PANI nanocomposite deposited on the modified\nglassy carbon electrode surface for nonenzymatic electrochemical sensing\nof dopamine. The synthesized nanocomposite was confirmed through X-ray\ndiffraction, Fourier transform infrared, Raman, and scanning electron\nmicroscopy characterization techniques. Additionally, electrochemical\nanalysis was conducted using cyclic voltammogram, differential pulse\nvoltammetry, and chronoamperometry. The process was determined to\nbe the diffusion-controlled oxidation of dopamine. Dopamine underwent\nspontaneous adsorption on the electrode surface through an electrochemically\nreversible mechanism. Despite various biological interfering factors,\nthe nonenzymatic electrochemical sensor demonstrated a remarkable\nlevel of selectivity toward dopamine. Cysteine-grafted Cu MOF/ZnO/PANI\nproduced the lowest dopamine detection limit, at 0.39 μM, and\nthe sensitivity was observed as 122.57 μAmM<sup>–1</sup> cm<sup>–2</sup>. Results have demonstrated that enhanced\ncatalytic and conductive properties of MOFs, combined with nanostructured\nmaterials, are the primary factors affecting the sensor’s performance.