Abstract
It is urgent that a convenient and sensitive technique of detecting Hg2+ be developed because of its toxicity. Conventional fluorescence analysis works with a single fluorescence probe, and it often suffers from signal fluctuations which are influenced by external factors. In this research, a novel dual-emission probe assembled through utilizing CdTe quantum dots (QDs) and rhodamine B was designed to detect Hg2+ visually. Only the emission of CdTe QDs was quenched after adding Hg2+ in the dual-emission probe, which caused an intensity ratio change of the two different emission wavelengths and hence facilitated the visual detection of Hg2+. Compared to single emission QDs-based probe, a better linear relationship was shown between the variation of fluorescence intensity and the concentration of Hg2+, and the limit of detection (LOD) was found to be11.4 nM in the range of 0–2.6 μM. Interestingly, the intensity of the probe containing Hg2+ could be recovered in presence of glutathione (GSH) due to the stronger binding affinity of Hg2+ towards GSH than that towards CdTe QDs. Based on this phenomenon, an IMPLICATION logic gate using Hg2+/GSH as inputs and the fluorescence signal of QDs as an output was constructed.
Highlights
Without being modified the surface further, CdTe quantum dots (QDs) were still able to disperse well in aqueous medium, which led to the formation of steady colloidal solutions directly
Peng et al, generalized an experience formula to calculate the size of the CdTe QDs based on a large number of experimental results [27]: D = 9.8127 × 10−7 λ3 − 1.7147 × 10−3 λ2 + 1.0064λ − 194.84 (1)
After adding 750 nM Hg ions, the luminescence intensity reduces quickly in less than 30 s, stays stably in 5 min. These results show intensity reduces quickly in less than 30 s, stays stably in 5 min. These results show that the reaction of Hg2+ with CdTe QDs is very quick and the luminescence is stable in a that the reaction of Hg2+ with CdTe QDs is very quick and the luminescence is stable in a long time, which are in favor of practical application
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. A facile, rapid, inexpensive and highly sensitive technique to detect mercury ions is still needed Toward this goal, in recent years, much effort has been focused on developing novel fluorescent detection systems for mercury, including sensors based on gold nanoparticles, organic dyes, quantum dots (QDs) and lanthanide-doped nanoparticles, etc. Among the research on dual-emission probes, there are many studies on the application of QD-based ratiometric fluorescent probes to metal ion detection, even including metal-free carbon QDs and graphene QDs [22,23,24]. In this study, aiming to explore the operability of QDs used as an optical signal probe, a novel probe using the dual-emission pathway was designed to detect mercury. On the basis of turn on/off property of the probe, an implication logic gate using Hg2+ /GSH as inputs and the fluorescence signal of emission of QDs as an output was designed
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