Water-Stable Tb-MOF for Highly Sensitive Fluorescent Sensing of Liver Disease Thiol Biomarkers and NOR Logic Gate Operation

Abstract

The development of efficient and stable fluorescent sensors for the detection of liver disease-related thiol biomarkers is of great clinical significance. In this work, a terbium-based metal−organic framework (Tb-MOF) with robust structure and excellent fluorescence properties was constructed via a solvothermal method. The material exhibited stability in aqueous phase and over a wide pH range, and showed highly selective and sensitive specific fluorescence quenching responses towards three liver disease-associated thiol biomarkers: glutathione (GSH), tiopronin (MPG), and 2-mercaptopropionic acid (MPA), with limits of detection (LODs) of 14.17, 15.01, and 18.79 μM, respectively. Based on the fluorescence on−off effect, a three-input NOR molecular logic gate was successfully fabricated to achieve intelligent logical discrimination of multiple targets. Meanwhile, a Tb-MOF@hydrogel system was developed to realize naked-eye visual detection. Spike recovery experiments in simulated physiological matrices confirmed the reliability of this sensor for practical biological sample detection. Notably, the fluorescence signal in aqueous phase is dominated by the broad-band emission of the ligand rather than the characteristic f−f emission of Tb³⁺. Combined with theoretical calculations, the dominant fluorescence quenching mechanism involving thiol-induced electronic structure reconstruction of the metal cluster and excited-state non-radiative internal conversion was elucidated. This study provides a new strategy for the design of multifunctional and intelligent lanthanide-based MOF biosensing platforms.