Rapid and ratiometric fluorescent detection of hypochlorite by glutathione functionalized molybdenum disulfide quantum dots

We proposed a rapid and ratiometric fluorescent detection method for hypochlorite by glutathione functionalized molybdenum disulfide quantum dots (G-MoS2 QDs). The G-MoS2 QDs were obtained through a hydrothermal method and the maximum fluorescence intensity was obtained at 430 nm under excitation of 360 nm. The fluorescence of G-MoS2 QDs at 430 nm can be weakened by curcumin through the inner filter effect, meanwhile the fluorescence of curcumin at 540 nm appeared. Hypochlorite can fast oxidize curcumin and weaken the inner filter effect, thus the fluorescence of curcumin at 540 nm decreased and the fluorescence of G-MoS2 QDs at 430 nm increased. This process takes only 30 s at room temperature. This is the rationale behind our rapid ratiometric fluorescent detection model for hypochlorite. Two linear detection ranges for hypochlorite are obtained with concentration from 1 to 20 μM and 20 to 30 μM, the limit of detection (LOD) was 11.5 nM. The standard spike recovery tests on milk and tap water samples showed satisfactory results, which extended the application of G-MoS2 QDs in the field of ratiometric fluorescence detection assays.