An Ultrasensitive Turn-On Ratiometric Fluorescent Probes for Detection of Ag+ Based On Carbon Dots/SiO2 and Gold Nanoclusters

Abstract

In recent years, ratiometric fluorescent probes have been widely used in biochemical sensors and bioimaging due to their accuracy, sensitivity, and visibility. In this paper, we constructed “turn-on” ratiometric fluorescent probes for the detection of Ag+ by coupling carbon dots-silicon spheres composites (named CSs) and gold nanoclusters (AuNCs). The dual-emission fluorescent probes (CSA) exhibited two fluorescence emissions at 448 and 610 nm respectively, under a single excitation of 380 nm. When Ag+ was added, the fluorescence intensity of AuNCs was enhanced thus, quantitative detection could be carried out within the ranges of 0-0.1 μM and 0.1-10 μM. The detection limit of Ag+ was 1.6 nM. Fascinatingly, when the concentration of Ag+ was increased, the fluorescence colour of the CSA ratiometric probes changed from blue to purple and then to pink. More importantly, the CSA composites were utilized to prepare portable agarose hydrogels for the detection of Ag+ by visualization. To the best of our knowledege, this is the first time ratiometric probes sensors have been used to visually detect Ag+. Therefore, this dual-emission ratiometric fluorescent probes have the potential to be applied to the detection of Ag+ in environmental monitoring and food safety assessment. In particularly, this technology can also be extended to other analytes.