One-pot hydrothermal synthesis of orange fluorescent silver nanoclusters as a general probe for sulfides

Abstract

Water-soluble fluorescent silver nanoclusters (AgNCs) with almost seven and nine silver atoms and a quantum yield (QY) of 5.38 ± 0.25% were successfully prepared via one-pot hydrothermal synthesis using polymethacrylic acid sodium salt (PMAA-Na) as a template. The as-prepared PMAA–AgNCs displayed a mono-distribution, they were uniform in size and the color of the fluorescence, emitting at 579 nm, was orange when excited at 502 nm. What is more, we found that the as-prepared PMAA–AgNCs could be quenched by sulfides based on the formation of a metal–ligand bond Ag–S, and thus sulfides could be sensitively detected by spectrofluorometry. As proof of concept, thiourea (TU) and other sulfides including cysteine (Cys), glutathione (GSH) and DL-methionine could be detected. For example, the color of the orange fluorescent AgNCs solutions darkened upon the addition of TU and the fluorescence of PMAA–AgNCs was quenched. The detection limit for TU was 6.10 μM in the linear range from 8.57 μM to 2.29 mM.