Flexible silver-metal-organic framework probe for highly sensitive and visual detection of tetracycline hydrochloride in freshwater fish

Tetracycline hydrochloride (TCH) is commonly used in aquaculture to prevent bacterial infections, renders the detection of its residues highly crucial for ensuring the safety of aquatic products. In this study, an Ag-based metal-organic framework, Ag-dcp (H₃dcp = 3-(3,5-dicarboxyphenyl)-6-carboxypyridine), was synthesized through hydrothermal method. The Ag-dcp framework offers environmental advantages, including a green synthesis process and potential for sustainable, eco-friendly applications. The uncoordinated carboxyl groups in Ag-dcp provide potential interaction sites for TCH, while the rhombic channels in the flexible structure of Ag-dcp that match the size of TCH effectively facilitate host-guest interactions. The Ag-dcp enables ratiometric fluorescence detection with high sensitivity via intramolecular charge transfer (ICT) triggered by TCH-induced ether bond rotation. The probe demonstrates a fluorescence color changes from blue to orange, achieving a detection limit as low as 0.14 μM and offering an ultrafast response time of just 10 s. Principal component analysis (PCA) was employed to effectively distinguish TCH from other tetracycline analogs (minocycline hydrochloride (MH) and doxycycline hydrochloride (DOX)), thereby enhancing the selectivity of the Ag-dcp probe. The fluorescence probe demonstrated performance comparable to HPLC in detecting TCH in freshwater fish. The detection strategy proposed here, based on the MOF structure, offers valuable insights for designing MOF materials and their specialized applications.