Phosphorus-doped carbon dots for sensing both Au (III) and l-methionine

Herein, one type of carbon dots (CDs) directed by l -threonine has been innovatively synthesized on the basis of a facile approach. Meanwhile, the CDs mainly consisted of C, O, N, and P according to the detailed characterizations. Importantly, the CDs obtained here not only exhibited the bright-blue fluorescence and generally acceptable stability, but also showed the promising for detecting Au 3+ and l -methionine. To be specific, the off-process by an obvious fluorescence quenching of the CDs achieved assaying Au 3+ , and Au 3+ could be removed by the introduction of l -methionine through the stronger interaction between Au 3+ and l -methionine, and thus leading to the fluorescence of CDs recovered. Consequently, the quantitative analyses of Au 3+ concentration in a linear range of 6 μM–1 mM was obtained along with the range from 80 μM to 1 mM for l -methionine. In addition, the practicability of this proposed method was validated by the detections of the lake samples, suggesting that it could broaden the sensing strategies for assaying both Au 3+ and l -methionine.