Microwave-assisted one-pot synthesis of highly luminescent N-doped carbon dots for cellular imaging and multi-ion probing
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The authors report on the microwave-assisted one-step synthesis of nitrogen-doped carbon dots (N-CDs) having a fluorescence quantum yield of 80% and a fluorescence lifetime of 15.0 ns. Citric acid and ethylenediamine were used as carbon source and as a nitrogen source, respectively. The N-CDs show excellent photostability over a wide range of pH values (4–11), even at high ion strength (2 M KCl) and after 4 h of continuous UV light irradiation. This makes these N-QDs promising candidates for fluorescent probes. Cellular toxicity test showed the N-CDs not to be cytotoxic to human nasopharyngeal carcinoma cells and human embryonic kidney cells even at 400 μg∙mL−1 levels after 48 h incubation. The fluorescence intensity of N-CDs at 445 nm is quenched by Fe(III), Hg(II), and chlorite ions, respectively. The N-CDs are shown to be viable fluorescent probes for the ions Fe(III), Hg(II), and chlorite. Respective detection limits are 12 nM, 0.8 nM, and 35 nM.
KeywordsTime-resolved fluorescence Quenching Quantum yield Fluorescence lifetime High-resolution transmission electron microscopy FTIR Stern-Volmer plot Cell imaging Ion analysis Cytotoxicity
This work was financially supported by National Natural Science Foundation of China (21563006, 21403039), Natural Science Foundation of Guangxi Province (2015GXNSFAA139033, 2016GXNSFBA380118), BAGUI Scholar Program of Guangxi Province of China, and Guangxi Colleges and Universities Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, Guangxi Teachers Education University.
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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