The Electrochemical Synthesis of Poly (Caffeic Acid)-Gold Nanoparticles on Pencil Graphite Electrode: Sensitive Determination of Antipsychotic Drug Clozapine and an Insight into the Electrooxidation Mechanism

This work presents a new simple and sensitive electrochemical sensor based on poly (Caffeic acid) (P(CA)) and gold nanoparticles (AuNPs) nanocomposite modified single-use pencil graphite electrode (AuNPs/P(CA)/PGE). The modification presents a facile approach based on electropolymerization and electrodeposition in one step. Cyclic voltammetry and electrochemical impedance spectroscopy were utilized for electro-synthesis, preparation, and sensor characterization. Electrocatalytic activities of AuNPs/P(CA)/PGE sensor were compared with PGE, AuNPs/PGE, and P(CA)/PGE. AuNPs/P(CA)/PGE sensor exhibited a proper electrocatalytic current toward clozapine (CLZ), which has a drug-efficient matter for threatening psychiatric disorders like schizophrenia. The quantification of CLZ in human plasma or urine levels is essential for proper antidote application, determining the therapeutic doses and gene polymorphism, or making judgments in forensic psychiatry. Differential pulse voltammetry was employed to quantify CLZ in Britton-Robinson buffer solution (pH 9.0). Sensor performance was tested due to the nanomaterial and pH effect. CLZ’s oxidation peak (about + 0.35 V) was linear in the (0.01–1000.0) μM linear range with the 3.0 nM detection limit. The analytical applicability of the sensor was carried out in pharmaceutical dosage forms, human serum, and human urine. The electrochemical oxidation mechanism of the antipsychotic drug CLZ was studied to highlight its pathways.