Design and application of metal-organic framework based chemo-fluorescent sensor for selective sensing of the full spectrum of tetracyclines in complex samples

Tetracyclines antibiotics (TCs) are widely used as broad-spectrum antibiotics, but their overuse leads to environmental pollution and threatens human health. Existing detection techniques (mass spectrometry, etc.) are complicated and cumbersome, and do not allow for rapid detection. Consequently, it is imperative to develop a sensing technology for rapid on-site detection of full-spectrum TCs residues. The UV–visible absorption peaks of TCs overlap with the blue fluorescence excitation wavelength range, which can “turn-off” the blue fluorescence based on the internal filtering effect. Additionally, the β-diketone bond of TCs can bind to Eu 3+ , sensitizing Eu 3+ to produce red fluorescence. Thus, we constructed a selective sensing chemo-fluorescent sensor using blue nitrogen-doped carbon dots (BCDs) and europium metal–organic framework (Eu-MOF). As the concentration of TCs increased from 0 to 2.6 μM, the sensor exhibited a continuous change in fluorescence color from blue to purple to red. The limit of detection is 1.37 nM with a response time of less than 1 s. Furthermore, this study presents a portable capillary chemo-fluorescent sensor detection kit, which consists of a capillary chemo-fluorescent sensor comprising BCDs/Eu-MOF encapsulated in a self-designed non-fluorescent glass capillary, as well as a color recognizer with a kit produced using 3D printing technology. This fluorescence sensing technology with excellent sensitivity and selectivity provides technical support for the rapid detection of TCs and the reduction of pollutant hazards to sustainable human development.