A facile rapid-response and on-site sensor for tetracycline detection in environmental water based on europium-doped carbonized polymer dots

With the increasing concerns about public safety and environmental protection, it is of great significance to establish a rapid and sensitive method to detect antibiotic residues in environmental samples. Herein, fluorescent carbonized polymer dots (CPDs) were synthesized and used for quantitative assay of tetracycline (TC) by chelating with europium ions (Eu³⁺). The green fluorescence of CPDs could be gradually quenched by TC via inner filter effect and static quenching mechanism, while the red emission of Eu³⁺ was remarkably enhanced through energy transfer and antenna effect. This ratiometric fluorescence Eu/CPDs-based sensor displayed a wide detection range of 0.05–56, 56–100 μM with a detection limit of 16.4 nM, and was triumphantly applied for TC analysis in water samples with high reliability and accuracy. Moreover, the polymeric structure in CPDs endowed the sensor with good long-term sensing stability up to 600 days. By integrating Eu/CPDs with portable capillary testing kit, a point-of-use device was constructed for facile determination of TC in river water samples with a short sample-to-answer analysis process in 2 min. Due to its easy operation, low-cost, and there is no pretreatment required, the capillary-based testing kit provides a new strategy for on-site and rapid detection of antibiotics in various environmental water samples.