A colorimetric sensor for the stable and selective detection of mercury ions using PAH-capped silver nanoparticles in an aqueous medium

In this study, we present a novel colorimetric method for the precise and sensitive detection of Hg ions utilizing silver nanoparticles (AgNPs) produced and stabilized in an aqueous medium using Poly allyl amine hydrochloride (PAH). Nanoparticles were prepared from silver nitrate and NaBH₄ along with CTAB at 26 ± 2 °C with an average size of 30.21 ± 6.5 nm. The prepared AgNPs solution exhibited yellowish brown color with a surface Plasmon peak at 420 nm. By adding Hg ions, the yellow color of the solution was transformed into a colorless suspension, and the color change was proportional to the Hg ion concentration. The presence of other metal ions had no effect on the color (sensitivity); confirming the selectivity of CTAB stabilized PAH capped AgNPs towards Hg ions. The generated probe has a 1 nM low detection limit when measured using a UV–visible spectrophotometer. The proposed approach has the potential to be utilized in real-time environments with greater precession by applying RGB values to make a revolutionary sensor using visible light imaging technique.