An ultrasensitive fluorescent sensor for organophosphorus pesticides detection based on RB-Ag/Au bimetallic nanoparticles

A simple strategy for the fabrication of a highly selective and sensitive fluorescence probe based on Rhodamine B (RB) modified silver/gold bimetal nanoparticles (RB-Ag/Au NPs) was developed. The fluorescence of RB-Ag/Au NPs remains quenched until exposure to organophosphorus pesticides (OPs). This is because that the coordination ability of Ag/Au NPs with OPs is stronger than that of Ag/Au NPs with RB. So RB would be displaced from the surface of the Ag/Au NPs, accompanying the fluorescence recovery of RB. The RB-Ag/Au NPs were characterized by transmission electron microscope (TEM) and fluorescence spectra. It can be applied to the determination of OPs in real fruit and water samples with the limit of detection (LOD) as low as 0.0018 ng/mL. The system combines organic with inorganic nanohybrids fluorescent sensors, which can be used for detecting OPs with ultrasensitivity. Moreover, the detection system presents excellent anti-interference ability when exposed to a sequence of interfering ions.