MoS₂ quantum dots as a unique fluorescent "turn-off-on" probe for the simple and rapid determination of adenosine...

We report a one-step hydrothermal method for the preparation of fluorescent molybdenum disulfide quantum dots (MoS₂ QDs) and demonstrate the feasibility of fluorescent "turn-off-on" sensing of adenosine triphosphate (ATP) by using the MoS₂ QDs. MoS₂ QDs having strong blue-green fluorescence at 506 nm and good water-solubility were successfully synthesized by using ammonium tetrathiomolybdate as a single precursor. The fluorescence of MoS₂ QDs was first quenched by Fe³⁺ through the formation of a MoS₂ QDs/Fe³⁺ complex. ATP with the ability to coordinate with Fe³⁺ caused the dissociation of MoS₂ QDs/Fe³⁺, resulting in the final release of MoS₂ QDs and the recovery of fluorescence through a one-step competitive chelating process that took only 10 min to reach equilibrium at room temperature (RT). Facile and rapid sensing of Fe³⁺ and ATP could thus be achieved through the fluorescent "turn-off-on" strategy. Good linear relationships were obtained over the concentration ranges of 0-200 μM for Fe³⁺ and 0-140 μM for ATP with a lowest detectable concentration of 5 μM for ATP. Satisfactory results were obtained when the method was applied to a standard addition recovery trial of ATP in human serum samples. No complex surface modification during the preparation or detection process was needed based on the fluorescent "turn-off-on" method of the MoS₂ QDs, which suggests its great potential in fluorescent sensing.