Nitrogen-doped carbon quantum dots as a fluorescent probe to detect copper ions, glutathione, and intracellular pH
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A facile one-step hydrothermal method was developed to synthesize nitrogen-doped carbon quantum dots (N-CQDs) by utilizing hexamethylenetetramine as the carbon and nitrogen source. The quantum yield (QY) of 21.7% was under the excitation wavelength of 420 nm with maximum emission at 508 nm. This N-CQD fluorescent probe has been successfully applied to selectively determine the concentration of copper ion (Cu2+) with a linear range of 0.1–40 μM and a limit of detection of 0.09 μM. In addition, the fluorescence of N-CQDs could be effectively quenched by Cu2+ and specifically recovered by glutathione (GSH), which render the N-CQDs as a premium fluorescent probe for GSH detection. This fluorescence “turn-on” protocol was applied to determine GSH with a linear range of 0.1–30 μM as well as a detection limit of 0.05 μM. For pH detection, there is good linearity in the pH range of 2.87–7.24. Furthermore, N-CQD is a promising and convenient fluorescent pH, Cu2+, and glutathione sensor with brilliant biocompatibility and low cytotoxicity in environmental monitoring and bioimaging applications.
KeywordsFluorescent probe Carbon quantum dots Copper ion Glutathione pH
This study received financial support from the National Natural Science Foundation of China (Nos. 21475152 and 21576296) and Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety (No. 2018TP1003).
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Conflict of interest
The authors declare that they have no conflict of interest.
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