A simple strategy for modulating the fluorescence of MoS₂ quantum dots (QDs) is described. The fluorescence of MoS₂ QDs was firstly switched off by the addition of Cr(VI), and the quenched fluorescence was further switched on by introducing ascorbic acid (AA) into the mixture. The fluorescence quenching of MoS₂ QDs by Cr(VI) was attributed to the fluorescence inner filter effect. After the addition of AA, Cr(VI) was reduced to Cr(III), and the fluorescence was restored. This finding has been applied for the fluorescent sensing of Cr(VI) in drinking water and AA in serum samples. In addition, the present method has been extended for turn-on sensing of an important biomarker alkaline phosphatase (ALP). There is a linear relationship between the fluorescence intensity and the concentrations of ALP in the range from 2.5 to 50 U/L, and the limit of detection is 0.34 U/L. The results showed MoS₂ QDs hold great potential as a multifunctional fluorescent probe for the detection of metal ions, biological small molecules, and proteins.

中文翻译：

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MoS 2量子点的可切换荧光：用于检测铬（VI），抗坏血酸和碱性磷酸酶活性的多功能探针

描述了一种简单的策略，用于调制MoS ₂量子点（QDs）的荧光。首先通过添加Cr（VI）来关闭MoS ₂ QD的荧光，然后通过将抗坏血酸（AA）引入到混合物中来进一步打开淬灭的荧光。MoS ₂的荧光猝灭Cr（VI）的QD归因于荧光内滤效应。加入AA后，Cr（VI）还原为Cr（III），并恢复了荧光。该发现已用于荧光检测饮用水中的Cr（VI）和血清样品中的AA。另外，本方法已经扩展用于重要生物标志物碱性磷酸酶（ALP）的开启感测。荧光强度与ALP浓度在2.5至50 U / L之间存在线性关系，检出限为0.34 U / L。结果表明，MoS ₂ QDs作为检测金属离子，生物小分子和蛋白质的多功能荧光探针具有巨大的潜力。