Silver nanoparticles as highly efficient and selective optical probe for sulphide via dendrimer formation in aqueous medium

Abstract

We herein report a highly efficient, cost effective, convenient as well as selective colorimetric probe for sulphide (S²⁻) in the form of silver nanoparticles (AgNPs) capped by an azonaphthol viz. 1-[(4-nitrophenyl)azo]-2-naphthol. A naked eye color change from bright yellow to colorless was observed upon the addition of S²⁻ to the AgNPs. A remarkable feature of this probe is the unique morphological transition of spherical AgNPs to dendritic architecture induced by S²⁻. Although dendritic AgNPs have been reported previously also by many workers through various methods. Here we are presenting a probe that not only selectively recognises S²⁻ colorimetrically but at the same time paves the way for the self-assembled dendritic structure of AgNPs. The lowest detection limit for S²⁻ was found to be 67 nM which is much lower than the maximum endurable level (15 μM) of S²⁻ in drinking water by World Health Organisation (WHO).