Fluorescent nanozyme for the dual-mode detection of tetracycline: Aggregation-induced luminescence and boosting peroxidase-like activity

In this work, we proposed a metal-organic framework (MOF) -based fluorescent nanozyme for tetracycline detection. The intrinsic peroxidase-like activity and fluorescence of the proposed fluorescent nanozyme are ascribed from the encapsulated hemin and fluorescent ligand, respectively. In the presence of tetracycline, the peroxidase activity is boosted through the π-π staking interaction with confined hemin, leading to colorless TMB being oxidized into dark blue. The aggregation of tetracycline in the MOF skeleton exhibited distinctive green fluorescence with emission at 535 nm. In contrast, the intrinsic blue fluorescence of MOF at 425 nm was quenched via the inner filter effect, enabling ratiometric fluorescence (F 535 /F 425 ) detection of tetracycline. Under the optimum conditions, the limit of detection for both colorimetric and fluorometry detection was calculated to be 27.2 and 4.1 nM, respectively. The proposed dual-mode probe also demonstrated excellent practical performance and promising in the on-field detection of tetracycline.