A novel Lu(III)-based rare-earth metal-organic frameworks for rapid detection of phosphate with triple-signal output.

Accurate detection of phosphate is vital for food safety, health, and environmental monitoring. This work presents a rectangular plate-like lutetium(III)-based metal-organic frameworks (Lu-MOFs) utilizing Lu(III) ions as metal centers and TCPP as the ligand. Phosphate selectively disrupts the ligand-to-metal charge transfer within Lu-MOFs via host-guest interactions, inducing dual optical responses of enhanced magenta fluorescence and brown chromogenic transition. A portable sensing platform was developed using Lu-MOFs nanoprobe for on-site detection of phosphate, which integrates triple-signal readouts including fluorescent, colorimetric, and smartphone-based RGB analysis, providing respective LOD of 0.44, 2.05, and 4.08 μM. Importantly, this method showed high accuracy and reliability in detecting phosphate in complex samples including chilled foods, instant foods, beverages and water sample, matching well with the standard molybdenum blue method. These findings highlight the promising application potential of Lu-MOFs nanoprobe in the fields of food safety and environmental monitoring.