Label-free fluorescence platform based on SiO2-coated CdTeS quantum dots for trace analysis of Ag+ in environmental water

In this study, a core-shell structural nano-composite material, namely CdTeS@SiO 2 , is synthesized by a simple silanization of Te-doped CdS quantum dots (CdTeS QDs). Through SiO 2 capping, CdTeS QDs not only improve the fluorescence performance effectively, but also greatly enhance the anti-interference ability in the environment. Based on its excellent optical properties , a novel fluorescence sensor is constructed for the ultramicro detection of Ag + . The fluorescence of CdTeS@SiO 2 is strongly quenched in the presence of Ag + and shows good linearity in the range of 0.005–5.0 μmol L −1 with a detection limit as low as 1.6 nmol L −1 . This is mainly due to its unique quenching mechanism: Ag +  destroys the spherical structure of SiO 2 and promotes the formation of non-radiative electron-hole pairs through electron transfer , leading to fluorescence quenching . At the same time, it competes with Cd for Te, S and MPA on the CdTeS surface, forming Ag–Te, Ag–S and Ag–MPA complexes attached to the CdTeS surface leading to wavelength red-shift. The feasibility of the proposed sensor is demonstrated through spiking experiments, which confirmed the potential value of the constructed fluorescence probe for real-world applications in detecting Ag + in environmental water.