Radiation synthesized poly(n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles as LSPR-based optical sensor for mercury ions estimation

Poly(n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles (PVP-Au-NPs) have been synthesized via a green-⁶⁰Co-Gamma radiolytic route and employed as a localized surface plasmon resonance (LSPR)-based optical sensor for estimation of trace quantities of Hg²⁺ ion in aqueous solutions. The in situ generated PVP-Au-NPs were characterized using UV–vis spectroscopy, transmission electron microscopy, and particle size analysis techniques. Reaction conditions were optimized to obtain uniformly dispersed PVP-Au-NPs with average particle size of 7.1 ± 1.6 nm (±s), which exhibited a narrow LSPR band at ∼527 nm. The decrease in LSPR band intensity of PVP-Au-NPs with increase in Hg²⁺ ion concentration was found to be linear in the Hg²⁺ ion concentration range of 0–100 nM. The LSPR-based PVP-Au-NPs optical sensor system was found to be selective for Hg²⁺ and independent of interference from other metal ions such as Ca^2+, Cu²⁺, Cd²⁺, and Fe²⁺ up to a concentration of 500 nM