Tea-derived carbon dots with two ratiometric fluorescence channels for the independent detection of Hg and HO.

Ratiometric fluorescence carbon dots (CDs) that serve as probes have attracted more attention on account of their unique optical properties, low toxicity, anti-interference, and internal reference. However, the facile fabrication of CDs with the aim of detecting multiple targets through mutually independent response channels is always a challenge. Herein, multifunctional label-free N-doped ratiometric fluorescence CDs (N-CDs) are developed from tea leaves extract and -phenylenediamine by a mild solvothermal method. The prepared N-CDs are tailored with nitrogen- and oxygen-containing functional groups on the surface and contribute to splendid hydrophilia. Two completely independent ratiometric fluorescence channels of N-CDs, respectively, respond to Hg and HO in a mutually independent manner. Based on the interactions of N-Hg and O-Hg, N-CDs achieve an excellently sensitive and selective detection for Hg in the channel of /, giving a linear relationship in the range of 0-50 μM. Also, a wide range of Hg concentration (0-100 μM) is linear to through UV-vis assay. Otherwise, the linear determination of HO content (0-30%) is realized in another channel (/). The good performance in the independent testing of Hg and HO, demonstrate that the proposed N-CDs have potential in multifunctional detection.