A self-assembled silver chalcogenide electrochemical sensor based on rGO-Ag2Se for highly selective detection of serotonin

Abstract

Herein, we have developed a sensitive and selective electrochemical sensor for the detection of serotonin (ST) by using self-assembled silver selenide on reduced graphene oxide (rGO-Ag2Se). The size of the Ag2Se nanoparticles was found to be approximately 60-70 nm by high-resolution transmission electron microscopy (HR-TEM). The absorption spectra of rGO-Ag2Se were observed at 258 nm using Ultraviolet-visible (UV-vis) spectroscopy. X-ray diff ;raction (XRD) confirmed the amorphous nature of rGO and the crystalline structure of Ag2Se nanoparticles. The elemental composition and the electronic state of the elements in rGO-Ag2Se were studied using X-ray photoelectron spectroscopy (XPS), which confirmed the presence of C, O, Ag, and Se. The glassy carbon electrode (GCE) surface was modified with rGO-Ag2Se and studied through cyclic voltammetry and impedance spectroscopy. Cyclic voltammetry revealed the electron transport behavior of rGO, which resulted in an increment in the redox peak current. The electrochemical impedance spectrum revealed that the charge transfer resistance (R-ct) of rGO-Ag2Se was 81.3 Omega and also confirmed the facilitation of electron diffusion at the rGO-Ag2Se/GCE. Under optimized conditions, rGO-Ag2Se/GCE displays better sensing ability for ST over a linear range from 0.1 to 15 mu M with a limit of detection (LOD) of 29.6 nM. Recoveries in the real time detection of ST in undiluted serum (97.8-101.9%) and the PBS diluted serum (96.0-102.3%) were in the excellent range. The fabricated sensor showed good stability (18 days), high selectivity, and satisfactory results on real sample, and is a good platform for rapid diagnosis of ST-linked diseases.