A label-free colorimetric sensor based on silver nanoparticles directed to hydrogen peroxide and glucose

Abstract

A simple method has been developed for preparation of silver nanoparticles (AgNPs) based on the use of graphene quantum dots (GQDs) as a reducing agent and a stabilizer. The synthesized nanocomposites consisting of silver nanoparticles and graphene quantum dots (AgNPs/GQDs) has been characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Ultraviolet–visible spectroscopy (UV–Vis), Fourier-Transform Infrared spectroscopy (FT-IR), Energy Dispersive X-ray spectroscopy (EDX) and Dynamic Light Scattering (DLS). Results indicate that monodisperse of AgNPs has been obtained with particles size ca. ∼ 40 nm and specific plasmon peak of silver nanoparticles at 425 nm by UV–Vis spectrum. Using AgNPs/GQDs nanocomposite, we have constructed a colorimetric sensor for hydrogen peroxide (H2O2) and glucose sensors based on the use of AgNPs/GQDs as both probes: capture probe and signal probe. The fabricated sensors perform good sensitivity and selectivity with a low detection limit of 162 nM and 30 μM for H2O2 and glucose sensing, respectively. Moreover, the biosensors have been successfully applied to detect glucose concentrations in human urine.