Detection of Silver Nanoparticles Using Green Synthesis of Fluorescent Nitrogen-Doped Carbon Dots

In this study, we synthesized simple water-soluble nitrogen-doped carbon dots (NCDs) using a one-step hydrothermal treatment of pomegranate juice and ammonium hydroxide. These low-cost NCDs exhibit high fluorescence emission, with a maximum emission at 395 nm, which can be specifically quenched by silver nanoparticles (AgNPs) via inner filter effect in the presence of l-cysteine. Our transmission electron microscopy analysis results show that l-cysteine induces the aggregation of NCDs beside the aggregated AgNPs, thereby quenching the NCD fluorescence emission. We used this phenomenon to develop a fluorescence method for the facile detection of AgNPs with a linear range of 8.3 x 10(-10)-3.3 x 10(-8) M and a detection limit of 3.8 x 10(-10) M (3 delta/slope). To evaluate the efficiency of the proposed method in a real sample, we used it to determine the concentration of AgNPs in spiked environmental water samples. The simplicity of the proposed procedure as well as its satisfactory recoveries introduces a new and potentially highly green method for the selective and rapid monitoring of AgNPs in environmental waters.