Self-Enhanced Ratiometric ECL Strategy Based on a Dual-Emission Ce/Tb-MOF Luminophore with Spatially Resolved Coreactant Delivery for Ultrasensitive Pro-GRP Detection

Dual-signal-output ratiometric electrochemiluminescence (ECL) platforms offer a promising solution to address the instability and inaccuracies associated with single-signal ECL detection. However, most existing ratiometric systems still rely on two independent luminophores, inevitably increasing the system complexity and compromising the detection accuracy. In this study, a bimetallic dual-ligand ECL luminophore, Ce/Tb-MOF, was synthesized via a solvothermal approach, exhibiting distinct anodic and cathodic ECL emissions from a single luminophore. To spatially regulate signal generation and avoid the complications of coreactant mixing, we designed a beacon nanostructure, TPA-β-CD@Au, that locally introduces the anodic coreactant tripropylamine (TPA) upon target binding. This enabled the implementation of a ″Reverse Regulation of Anodic/Cathodic Signals″ strategy, wherein target recognition simultaneously suppresses cathodic emission and enhances anodic emission, achieving internally calibrated signal output. Based on this mechanism, a highly sensitive ECL immunosensor was developed for the detection of Pro-gastrin-releasing peptide (Pro-GRP). The sensor exhibited excellent analytical performance, including a broad dynamic range (100 fg/mL to 100 ng/mL), a low detection limit of 52.4 fg/mL, and strong anti-interference capability. This work presents a robust and simplified ratiometric ECL platform and provides valuable insights into the rational design of multifunctional MOF-based biosensors for clinical diagnostics.