A reusable ratiometric fluorescent probe for the detection and removal of doxycycline antibiotic demonstrated by environmental sample investigations

Tetracycline antibiotic residues have attracted worldwide attention due to the serious damage to human health and the environment. However, most of the reported fluorescent probes were based on a single fluorescence channel-based response, which often suffered from signal fluctuation-induced poor reproducibility. Herein, by taking advantage of the unique properties of zeolitic imidazolate frameworks (ZIFs), a novel europium-doped ZIF nanocomposite (ZIF-Eu) was reported for the detection of doxycycline (DOX) in a ratiometric fluorescence manner. The synthesized probe only showed blue fluorescence at 420 nm since the fluorescence of Eu was quenched by the coordinated water molecules. However, due to the strong coordination ability of DOX to Eu atoms, the probe solution demonstrated an obvious fluorescence enhancement at 615 nm in the presence of DOX, while the blue fluorescence signal remained unchanged, realizing a ratiometric fluorescence response to DOX with a good linear range from 1 to 9 mu M and a detection limit of 49 nM. Interestingly, it is found that DOX could be discriminated from other tetracycline antibiotics using this ratiometric fluorescent probe. In addition, direct detection of DOX in soil samples, the DOX removal efficiency and the reusability of the proposed ZIF-Eu nanocomposite were demonstrated to evaluate its potential in environmental remediation application.