Crystalline Energy Funneling in Mixed-Ligand Zr-MOFs Drives Radical-Triggered ECL Amplification for Ultrasensitive Thrombin Sensing

Harnessing crystalline architectures to direct exciton migration presents a promising avenue for electrochemiluminescence (ECL) signal amplification in biosensing. Herein, we report a structurally orchestrated ECL platform based on a mixed-ligand zirconium metal-organic framework (Zr-MOF), assembled from 1,3,6,8-tetrakis(<i>p</i>-benzoic acid)pyrene (TBAPy) and zinc tetrakis(4-carboxyphenyl)porphyrin (ZnTCPP). The nanoscale colocalization of donor-acceptor pairs within a crystalline lattice establishes an intraframework energy funneling pathway, enabling directional resonance energy transfer (RET) from TBAPy to ZnTCPP with an efficiency of up to 76.5%. Beyond RET, radical-triggered excitation involving TBAPy^•- and superoxide (O₂^•-) further activates ZnTCPP-centered ECL emission, resulting in a 3-fold enhancement compared to single-ligand controls. By leveraging this synergistic amplification, an aptamer-gated, signal-off ECL biosensor was constructed for femtomolar-level thrombin detection (limit of detection: 0.47 fM) with exceptional selectivity. This work exemplifies a crystalline energy-programmed approach to coupling exciton dynamics with redox-active interfaces, offering a mechanistically traceable and highly sensitive platform for advanced bioanalytical applications.