N-doped carbon dot as fluorescent probe for detection of cysteamine and multicolor cell imaging

In the present work, we developed nitrogen-doped carbon dots (NCDs) as novel fluorescence probe for the quantitative detection of cysteamine. NCDs were synthesized by a rapid one-pot microwave assisted pyrolysis method using tartaric acid as the source of carbon and urea as N-dopant. The synthesized NCDs possessed multicolor (blue, green and red) fluorescence and excitation wavelength dependent emission behaviour. It was found that the fluorescence intensity of NCDs was quenched with the addition of cysteamine which may be attributed to the formation of non-fluorescent ground state complex. Under optimum condition, the linear response was observed in the range of 10–210 μM and the detection limit was found to be 75.6 nM for sensing the cysteamine. Moreover, the proposed sensing methodology showed high selectivity for cysteamine over a number of interfering metal ions and amino acids. The remarkable biocompatibility of NCDs was investigated in MDA-MB-231 breast cancer cells which impacts its immense potential for diagnostic purposes. The proposed sensing method is thus simple with high sensitivity and excellent selectivity. We expect that this method will become a potential tool for the detection of cysteamine in biological samples.