Dual-ligand Zr-based metal–organic framework for ratiometric fluorescence sensing and imaging of copper ion in biological system

Excessive accumulation of copper ions in the human body is closely associated with various diseases, including gastrointestinal disorders, neurological dysfunction, and hepatorenal diseases. Thus, reliable detection techniques for Cu²⁺ in blood and cells are crucial for early diagnosis and pathology studies. In this work, a dual-ligand Zr-MOF (TCPP@UiO-66-(OH)₂) was successfully synthesized in situ using tetrakis(4-carboxyphenyl)porphyrin (TCPP) and 2,5-dihydroxyterephthalic acid (H₂BDC-(OH)₂) as ligands via a simple one-pot method. This dual-ligand Zr-MOF was reported as a ratiometric fluorescence sensing probe for Cu²⁺ detection, featuring with single excitation and dual-emission. The green-emitting H₂BDC-(OH)₂ serves as an effective internal reference for efficient correction in complex environments, while TCPP provides active sites for Cu²⁺ recognition, with its red emission being selectively quenched by Cu²⁺. The fluorescence probe demonstrates excellent selectivity, high sensitivity, a broad linear detection range (1 uM-12 uM), and a low limit of detection (42 nM). Moreover, the developed fluorescence sensing platform has been successfully applied to Cu²⁺ detection in human serum and imaging in living cells, highlighting its significant potential for biosensing applications.