Monophasic molybdenum selenide-reduced graphene oxide nanocomposite sheets based immunosensing platform for ultrasensitive serotonin detection

Abstract

Herein, an ultrasensitive and label-free immunosensing platform has been fabricated; based on monophasic molybdenum tetraselenide-reduced graphene oxide nanocomposite (mnMo3Se4@RGO) sheets for serotonin biomarker detection. We used one pot low temperature hydrothermal process for the synthesis of mnMo3Se4@RGO and functionalization was carried out using APTES (3-aminopropyl triethoxy silane). Afterward, the covalent bioconjugation of anti-serotonin onto APTES/mnMo3Se4@RGO/ITO electrode was carried out via EDC-NHS coupling chemistry followed by addition of BSA (bovine serum albumin) for blocking of the non-specific binding sites onto the electrode surface. The structural, morphological and functional properties of mnMo3Se4@RGO and fabricated electrodes were characterized using XRD (X-ray diffraction), Raman spectroscopy, SEM (scanning electron microscopy), HR-TEM (High-resolution transmission electron microscopy) and FT-IR (Fourier-transform infrared spectroscopy). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used to demonstrate the electrochemical properties as well as response studies of the developed platform. The developed immunosensing platform (BSA/anti-serotonin/APTES/mnMo3Se4@RGO/ITO) for serotonin detection shows wider linear detection range (10–1200 nM), higher sensitivity (18.4 µA log(nM)−1 cm−2) and remarkable lower detection limit (2.5 nM). We believe that the developed immunosensor has the potential to detect serotonin and also gives the understanding of the disease associated with low and high level of serotonin.