One-pot hydrothermal synthesis of nitrogen and sulfur co-doped carbon dots and their application for sensitive detection of curcumin and temperature

In this study, excitation-independent emission nitrogen and sulfur co-doped fluorescence carbon dots (N,S-CDs) was fabricated by using a simple and efficient one-step hydrothermal treatment with sodium citrate and thiourea as precursor. We found that the obtained N,S-CDs displayed excellent optical properties and emitted strong blue fluorescence under the 365 nm UV lamp. The relative quantum yield was as high as 26.9% using quinine sulfate as reference. The fluorescence of N,S-CDs could be effectively quenched when curcumin(CM) was added into the solution based on the inner filter effect (IFE). The as-prepared N,S-CDs without any modification could be as switch-off fluorescent probe for fluorescence turn-off detection of CM in the range of 0.15-18.0 mu mol L-1 with the detection limit of about 0.04 mu mol L-1. Moreover, the as-prepared N,S-CDs were successfully employed to the detection of CM in urine samples with satisfactory results. Noticeably, the N,S-CDs showed a distinct temperature-sensitive feature and used to construct fluorescent temperature sensor. Therefore, a convenient approach was proposed that N,S-CDs could be used as a fluorescent probe for rapid and sensitive detection of curcumin and temperature.