Dual-mechanism detecting fluoride and tetracycline in food matrices using red-emitting carbon dots

Excessive exposure to fluoride and tetracycline can cause severe dental damage, including tetracycline-induced tooth discoloration and dental fluorosis. Herein, we introduce a dual-mechanism sensing strategy using red-emitting carbon dots (R-CDs) for the independent detection of fluoride and tetracycline. A key advantage of R-CDs as sensors is their ability to selectively identify both analytes through long-wavelength emission with a large Stokes shift. For fluoride detection, we developed a fluorescence-enhanced sensor based on R-CDs-Fe³⁺ via a competitive binding mechanism. Meanwhile, tetracycline detection was achieved using a fluorescence-quenching sensor leveraging static quenching and the internal filter effect (IFE). The successful quantification of fluoride and tetracycline in food matrices demonstrates the practical potential of R-CDs in food safety monitoring. Additionally, this study presents a novel framework for designing multi-target detection systems using a single type of carbon dots across different sensing mechanisms.