Fluorescent nanosensor platform based on CdTe QDs-aptamer probe and MoS2 nanosheets for detection of silver(Ⅰ) ions

Silver ion (Ag + ) is a significant metal pollutant known for its potential toxicity to aquatic life and human health. Long-term exposure to toxic heavy metals will do great harm to humans and animals. Therefore, it is urgent to develop an efficient method for detecting Ag + . Herein, we have developed a simple, sensitive, highly selective and cost-effective fluorescence “off-on” mode nanosensor based on environmentally friendly and biocompatible materials for sensitive detection of Ag + in aqueous environments. In this sensing strategy, Ag + can specifically interact with the cytosine-cytosine (C-C) mismatch in single-stranded DNA, where Ag + induces the folding of single-stranded DNA to form hairpin structures and stable metal-mediated cytosine-Ag + -cytosine (C-Ag + -C) base pairs via coordinate bonds. Massive changes to the molecular volume and fluorescence signal are brought about by the development of the C-Ag + -C complex. To reach our objective, CdTe quantum dots (CdTe QDs) with low toxicity and strong signal were prepared as fluorophores for detecting Ag + target. Using the inner filter effect (IFE) between hydrophilic CdTe QDs and MoS 2 nanosheets to achieve the fluorescence quenching of the CdTe QDs, and the subsequent fluorescence turn-on process is due to the formation of C-Ag + -C complex, which makes its probe fluorophore far away from the surface of MoS 2 nanosheets, thus realizing fluorescence “off-on” sensing strategy. The proposed nanosensor can distinguish Ag + from other interfering ions with high sensitivity and selectivity. The nanosensor proposed here possesses a quick response time of 8 min and an ultra-low detection limit of 1.1 nM.