A ratiometric fluorescent nanoprobe based on CdSe quantum dots for the detection of Ag+ in environmental samples and living cells.

With the widespread application of Ag+ in modern life and industry, the potential hazardous effects of Ag+ to environment and humans have attracted great concerns. Thus, effective and rapid strategies for Ag+ detection are highly desirable. In this paper, a novel ratiometric fluorescence sensor using CdSe quantum dots (QDs) has been constructed for sensitive and selective detection of Ag+, which is based on the formation of Ag2Se QDs. CdSe QDs were initially prepared and showed single wavelength emission at 510 nm. When Ag+ exists, a rising peak appeared at 650 nm and the emission at 510 nm declined, exhibiting distinct ratiometric fluorescence emission (I650/I510) characteristic with a linear response over the Ag+ concentration range of 0.01-4 μM. Significantly, the fluorescence changed from green to red. The detection limit of the constructed sensor is 1.4 nM. Furthermore, the sensing assay can be successfully applied to detect Ag+ in real water samples and living cells.