Facile surface modification of the poly(l-cysteine) on 2D-printed reduced graphene oxide electrode to fabricate a highly sensitive electrochemical sensor for determining the antipsychotic drug olanzapine

Amino acid-based polymers are alternative modifiers for electrode surface modification that can be simply and rapidly synthesized through electrochemical methods. Hence, we aim to develop a novel and easy-to-construct electrochemical sensor based on a two-dimensional-printed reduced graphene oxide electrode modified with poly(l-cysteine) for the determination of the antipsychotic drug olanzapine. The poly(l-cysteine) was employed as the only modifier for electrode surface modification, which was conducted via a single-step electropolymerization procedure. The surface composition and morphology of the developed sensor were examined by using a field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The electrochemical characterization of the sensor was also performed by utilizing cyclic voltammetric and electrochemical impedance spectroscopic techniques. All electrochemical parameters and analytical performances of interest were thoroughly investigated. Under optimal conditions, the developed approach showed broad linear dynamic ranges of 10–1000 and 1500–5000 nM and a low detection limit of 0.91 nM in the detection of trace amounts of olanzapine. When the proposed approach was used to analyze olanzapine in human serum samples to verify its feasibility, it exhibited high accuracy and good precision. In contrast to conventional electrodes, our newly developed electrochemical electrode could be an appropriate device for monitoring the effectiveness and safety of the antipsychotic drug olanzapine.