Cysteine-Grafted Cu MOF/ZnO/PANI Nanocomposite for Nonenzymatic Electrochemical Sensing of Dopamine

Electrochemical sensing has shown great promise in monitoring neurotransmitter levels, particularly dopamine, essential for diagnosing neurological illnesses like Parkinson's disease. Such techniques are easy, cost-effective, and extremely sensitive. The present investigation discusses the synthesis, characterization, and potential use of a cysteine-grafted Cu MOF/ZnO/PANI nanocomposite deposited on the modified glassy carbon electrode surface for nonenzymatic electrochemical sensing of dopamine. The synthesized nanocomposite was confirmed through X-ray diffraction, Fourier transform infrared, Raman, and scanning electron microscopy characterization techniques. Additionally, electrochemical analysis was conducted using cyclic voltammogram, differential pulse voltammetry, and chronoamperometry. The process was determined to be the diffusion-controlled oxidation of dopamine. Dopamine underwent spontaneous adsorption on the electrode surface through an electrochemically reversible mechanism. Despite various biological interfering factors, the nonenzymatic electrochemical sensor demonstrated a remarkable level of selectivity toward dopamine. Cysteine-grafted Cu MOF/ZnO/PANI produced the lowest dopamine detection limit, at 0.39 μM, and the sensitivity was observed as 122.57 μAmM^-1 cm^-2. Results have demonstrated that enhanced catalytic and conductive properties of MOFs, combined with nanostructured materials, are the primary factors affecting the sensor's performance.