A multi-responsive Tb-doped MOF probe for highly specific breath volatile biomarker recognition of lung cancer

The development of probes that are sensitive and selective for the detection of breath volatile biomarkers is crucial for early diagnosis of lung cancer (LC). Luminescent metal-organic frameworks (LMOFs) have attracted great attention due to their adjustable surface and excellent optical properties. Herein, we successfully prepared a series of bimetallic Tb-UiO-66 materials with large Stokes shifts for fluorescence sensing of breath volatile biomarkers (especially styrene and ethylbenzene (EB)) via a one-pot approach. The environmentally friendly ethanol solution was used as the fluorescence sensing solvent, which indirectly introduced intermolecular hydrogen bonding with the adjustment of the ratio of ethanol and water, realizing the unique sensing of Tb-UiO-66 for styrene and EB with single excitation and multiple emission. The limits of detection (LODs) of Tb-UiO-66 (1 : 103) for styrene and EB were 18.3 ppb and 0.45 ppm, respectively, which were the lowest recorded of all reported LMOFs so far. Additionally, Tb-UiO-66 (1 : 103) displayed good anti-interference ability even in the presence of other potentially interfering VOC biomarkers, such as 2-pentanone and cyclohexane. The fluorescence quenching of styrene was mainly due to the excited-state intramolecular proton transfer (ESIPT) and fluorescence resonant energy transfer (FRET), while twisted intramolecular charge transfer (TICT) and FRET were responsible for quenching of EB. Furthermore, Tb-UiO-66 (1 : 103) shows good recycling performance for sensing styrene and EB. More importantly, the detection of gaseous styrene and EB can be directly realized with the naked eye using Tb-UiO-66 (1 : 103) test strips.