Electrochemical sensor based on electropolymerized Orange G and oxygenated carbon nanotubes for the detection of dopamine

Electropolymerization is a widely applied technique in the development of electrochemical sensors due to the formation of films that enable sensitive and selective detection and quantification of electroactive analytes. A nanocomposite film composed of electropolymerized Orange G dye and oxidized multi-walled carbon nanotubes was used to develop an electrochemical sensor. The nanocomposite film exhibited a pronounced electrocatalytic effect on the oxidation of dopamine, a critical electroactive neurotransmitter used to evaluate the effectiveness of the modified electrode as a sensor. By employing electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy, the formation of the conductive polymeric film was confirmed, and the analyte response was tested at each step of sensor construction. Combining oxygenated carbon nanotubes with the Orange G polymeric film resulted in lower charge transfer resistance and reduced interference from uric acid and ascorbic acid in the dopamine signal. A detection limit of 38.2 nmol L⁻¹ was achieved for dopamine determination, along with a good recovery percentage (96.64–102.57 %) in a human serum sample matrix. Therefore, the constructed nanocomposite film showed significant potential for application as a dopamine sensor, exhibiting good repeatability (RSD = 3.6 %) and reproducibility (RSD = 6.9 %).