Fluorescent carbon dots based sensing system for detection of enrofloxacin in water solutions

Enrofloxacin (ENR) is one of the environmental pollutants need to remove in many wastewater treatment processes. Traditional methods for measuring ENR are often complex and time-consuming. Due to their low cost and high efficiency, fluorescent carbon dots can be used for detecting many pharmaceuticals. In this contribution, nitrogen doped fluorescent carbon dots (N-CDs) were firstly synthesized with a fluorescence quantum yield of 20.5%. The N-CDs can emit strong blue fluorescence when excited at 368 nm and there exist a large amount of carboxyl, hydroxyl and amine groups on their surfaces. In addition, the fluorescence of N-CDs could be quenched in the presence of Cu²⁺, which could be gradually restored upon adding ENR. Thereby, a rapid and sensitive fluorescent sensing strategy based on the fluorescence recovery of the N-CDs-Cu²⁺ system was designed for selective detection of ENR. The possible sensing mechanism was also proposed in terms of the results of resonance Rayleigh scattering, UV-vis absorption and Fourier transform infrared (FITR) spectra. Under the optimal condition, a good linear relationship was obtained for ENR determination with concentrations ranging from 1.0 to 15.0 μg·mL^-1 and the detection limit of 0.16 μg·mL^-1 was achieved. Finally the proposed sensing system was applied for the detection of ENR in real water samples with satisfactory results.