Ultrasensitive Fluorescent Detection of Tetracycline Based on Selective Supramolecular Interaction of Nitrogen Chlorine Co–Doped Graphene Quantum Dots

Herein, a simple bottom-up method for producing nitrogen and chlorine co-doped graphene quantum dots (N, Cl-GQDs) was proposed by utilizing citric acid and 3,4-dichloroaniline via hydrothermal treatment, and a fluorescent sensor for the detection of tetracycline was demonstrated. These synthesized N, Cl-GQDs consist mostly of 1–3 layers with a uniform size of about 4.5 nm. Strong blue fluorescence with a quantum yield of 23.2 % was observed from the obtained N, Cl-GQDs when irradiated with a 365 nm UV light. Systematic studies indicate that N, Cl-GQDs have several superior features, including excitation-independent emission, high monodispersity, good stability and water solubility. Moreover, the fluorescence intensity of N, Cl-GQDs could be significantly quenched by the addition of a small amount of tetracycline. Finally, a fluorescent probe for the detection of tetracycline with a detection limit of 68 nM was proved, which exhibits great potentials for biosensors and biological imaging.