In situ-grown ambient-temperature dual-emissive RhB/COF@ZIF-90 composite for ratiometric fluorescence detection of tetracycline in foods

In this work, a fluorescent sensor based on dual-emissive RhB/COF@ZIF-90 composite was fabricated for ratiometric detection of tetracycline (TC) residues in foods. To mitigate the aggregation-caused quenching (ACQ) effect of TAPB-DMTA COF, ZIF-90 on TAPB-DMTA COF composite was fabricated by an in situ growth strategy. Rhodamine B (RhB) was subsequently encapsulated within the ZIF-90 framework to construct a dual-emission fluorescent probe. When TC was present, the fluorescence signal at 460, 525 and 570 nm increased linearly with the amount of TC. The I 570 /I 460 and I 525 /I 570 ratio signals were demonstrated in the two linear ranges of 5–100 nM and 0.1–20 μM concentrations of TC, respectively. This multi-signal sensor exhibited a low detection limit of 0.29 nM, enabling highly sensitive detection of TC. Furthermore, this work paves the way for developing other MOF/COF hybrids as multi-emission fluorescent sensors for application in antibiotic sensing in foods.