Stable Ag nanoclusters-based nano-sensors: Rapid sonochemical synthesis and detecting Pb2+ in living cells

The preparation and applications of fluorescent Ag nanoclusters (AgNCs) have been developed rapidly. However, the poor stability and time-consuming in synthesis process limit their further application. Herein, a rapid sonochemical route is used to synthesize fluorescent AgNCs using hydrazine hydrate as reducing agent and glutathione (GSH) as capping agent. The AgNCs would be formed quickly (similar to 15 min) due to presence of ultrasonic wave, which show red fluorescence (lambda(em) = 645 nm), small size (similar to 2 nm) and good dispersion in aqueous solution. Moreover, GSH, as protecting agent on the surface of resultant AgNCs, has many functional groups including carboxyl and amino groups which make NCs show high photo-, time-, metal- and pH-stability. Then a stable Ag nanoclusters-based nano-sensor is designed for highly sensitive and selective label-free detection of Pb2+. This nanosensor shows a potential application as probe for monitoring Pb2+ not only in aqueous solution but also in living cells. Thus, these stable and fluorescent AgNCs could work as an alternative to conventional fluorescence probes for biolabeling, sensing and other applications. (C) 2016 Elsevier B.V. All rights reserved.