Paper-based colorimetric sensor based on graphene oxide/platinum-gold nanocomposites for simultaneous detection of Hg2⁺ and Ag⁺

Abstract

The presence of Hg²⁺ and Ag⁺ ions in the environment represents a considerable risk to both human health and ecological systems. Current detection methodologies are typically characterized by their complexity, protracted duration, and inability to simultaneously identify these ions. This study introduces an innovative paper-based colorimetric sensor that employs graphene oxide/platinum-coated gold nanoparticles (GO/Pt@AuNPs) composites, marking the first instance of achieving simultaneous, rapid, low-cost, and visually quantifiable detection of Hg²⁺ and Ag⁺. The sensor capitalizes on the peroxidase-like activity of GO/Pt@AuNPs to facilitate the oxidation of tetramethylbenzidine (TMB) by hydrogen peroxide (H₂O₂), resulting in the production of a blue chromophore. The catalytic activity is selectively inhibited by Hg²⁺ and Ag⁺ ions, which leads to a decrease in color intensity that is directly proportional to the concentration of the ions. For quantitative analysis, Hg²⁺ was selectively masked using ethylenediaminetetraacetic acid (EDTA). Experimental findings have indicated detection limits of 0.05 μM for Hg²⁺ and 2.5 μM for Ag⁺, with a detection time of merely 1 min. This method is distinguished by its high selectivity, portability, and capability for naked-eye quantification, rendering it particularly suitable for the rapid on-site detection of Hg²⁺ and Ag⁺ in environmental water, food, and biological samples. This is an effective approach for monitoring pollutants in settings with limited resources.