Ascorbic acid detector based on fluorescent molybdenum disulfide quantum dots

A rapid and facile method is reported for the detection of ascorbic acid using molybdenum disulfide quantum dots (MoS₂ QDs) as a fluorescence sensor. Water-soluble and biocompatible MoS₂ QDs with the maximum fluorescence emission at 506 nm have been successfully synthesized by hydrothermal method and specific detection for ascorbic acid (AA) was constructed to utilize the modulation of metal ion on the fluorescence of MoS₂ QDs and the affinity and specificity between the ligand and the metal ion. The fluorescence of MoS₂ QDs was quenched by the irreversible static quenching of Fe³⁺ through the formation of a MoS₂ QDs/Fe³⁺ complex, while the pre-existence of AA can retain the fluorescence of MoS₂ QDs through the redox reaction between AA and Fe³⁺. Based on this principle, a good linear relationship was obtained in the AA concentration range 1 to 150 μM with a detection limit of 50 nM. The proposed fluorescent sensing strategy was proven to be highly selective, quite simple, and rapid with a requirement of only 5 min at room temperature (RT), which is particularly useful for rapid and easy analysis. Satisfactory results were obtained when applied to AA determination in fruits, beverages, and serum samples as well as AA imaging in living cells, suggesting its great potential in constructing other fluorescence detection and imaging platforms.