Highly sensitive fluorescence detection of tetracycline in food samples using a Zn5 cluster-based zwitterionic metal-organic framework

A brilliantly stable and luminescent Zn5-cluster-based metal-organic framework, namely {[Zn5(bci)4(OH)2(SO4)2].4H2O} (MOF 1), was successfully constructed by zwitterionic ligand H2bciCl (1,3-bis(4-carboxybenzyl)-1H-imidazol-3-ium chloride) in solvothermal condition. MOF 1 which crystallized in tetragonal crystal system P41212 space group with 8-connected bcu body-centered-cubic topology exhibits excellent organic solvent stability, water stability, and pH stability. As a new fluorescence sensor, MOF 1 can selectively, sensi-tively, rapidly and recyclably detect tetracycline (TCY) antibiotic in aqueous solution through fluorescence quenching effect with a low detection limit of 0.083 mu M. Additionally, as a fluorescent detection material with potential practical application value, MOF 1 is able to detect TCY in chicken, egg and fish samples with excellent recovery rates. The reasonable fluorescent detection mechanism has been confirmed, which may be a combi-nation of fluorescence resonance energy transfer (FRET) and photoelectron electron transfer (PET).