Electrochemical sensor based on graphene oxide/chitosan/ZnO/Au nanocomposite for the determination of losartan

Detection and measurement of biological species and drug molecules are important, so that they have a significant part of the research not only in the field of diagnosis of diseases, but also in various therapeutic areas [1]. Undoubtedly, one of the prominent approaches at the scientific-research level is to use nanotechnology to design and manufacture a variety of biological and chemical sensors in order to increase the sensitivity and improve their specific performance. Graphene has been used for the sensitive determination of various drugs molecules, due to their excellent conductivity because of π-π staking and synergetic effects with other materials [2]. Chitosan as a natural polymer is a suitable material with promising characteristics to be used for biosensors. Metal nanoparticles (MNPs) based electrochemical sensors and biosensors are playing important role in diagnostic device [3].In this study, a highly sensitive electrochemical sensor based on glassy carbon electrode modified by graphene oxide, chitosan, gold metal nanoparticles, and zinc oxide with a constant potential method for measuring losartan drug. The morphology and structure of the nanocomposite were characterized by the Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Electrochemical and electro catalytic behavior of this modified electrode for identification and measurement of losartan were carried out in pH 7.0 PBS, by Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV). Under optimum conditions, DPV indicated linear relationship between oxidation peak current and losartan concentration in the range of 0.5-18.0 μM with detection limit of 0.073 μM. The sensor was successfully applied for the highly sensitive determination of losartan in pharmaceutical products and urine samples with satisfactory results.