Electrochemiluminescence Resonance Energy Transfer Biosensor Based on Self-Enhanced Terbium-Based Metal–Organic Frameworks with Antenna Effect for Sensitive MicroRNA-155 Detection

O quencher, which has a broad UV-Vis absorption range, was introduced for resonance energy transfer (RET)-based suppression. A dual-output toehold-mediated strand displacement (TMSD) strategy was employed to enable target recycling and "on-off" signal control. Using microRNA-155 (miR-155), a biomarker implicated in multiple cancers, as a model target, the biosensor exhibited a wide linear detection range from 10 aM to 1 nM and an ultralow detection limit of 4.7 aM. It also had excellent specificity and achieved high recovery rates when applied to detect human serum and cancer cell samples. Overall, this work describes a robust strategy for integrating Ln-MOF emission platforms with nucleic acid amplification, presenting a powerful tool for the ultrasensitive detection of clinically relevant miRNA.