Fluorescence determination of the total amount of tetracyclines by a flavonol-based supramolecular sensor

Tetracyclines (TCs) are a group of broad-spectrum antibiotics against multiplying microorganisms yet with several adverse effects on humans. Since all types of TCs have the similar chemical skeleton and mechanism of action, quantification of total amount of TCs in the environment was of particular importance. To date, dozens of fluorescent probes have been reported for TCs detection, but only very few of them enabled detection of total TCs. In this study, we report a novel supramolecular sensor constructed by human serum albumin as the recognition moiety and a flavonol fluorophore as the indicator. Under the 370 nm UV excitation, this sensor exhibits the rapid response (5 s), acceptable sensitivity (limit of detection ∼ 0.58 μM), long dynamic detection range (0-20 μM), prominent specificity, and excellent anti-interference properties for analysis of total TCs. The mechanism was carefully validated using ¹H NMR, fluorescence titration experiments, molecular docking, and mass spectrometry. We expect this work can inspire more sensor design for TCs quantification.