Lewis Acid-Mediated Interfacial Microenvironment Engineering for Enhanced Cathodic Electrochemiluminescence Aptasensing of Perfluorooctanoic Acid Based on Ligand Defect-Modulated MIL-88B(Fe) MOF.
Abstract
Efficient interfacial activation of co-reactants to generate sufficient radical intermediates is fundamental to constructing high-performance co-reactant-type electrochemiluminescence (ECL) biosensing platforms. This work reported a microenvironment-engineered cathodic ECL strategy by integrating PSA-HOF as the luminophore with defect-engineered MIL-88B(Fe) as the co-reactant activation modulator for the sensitive detection of perfluorooctanoic acid (PFOA). Specifically, pyrrole-2-carboxylic acid-regulated Pca-MIL-88B(Fe), as a defect-engineered material, generated coordinatively unsaturated, electron-deficient Fe centers with exceptional Lewis acidity. These defect-derived sites established an optimal interfacial microenvironment for persulfate activation by critically enhancing K2S2O8 enrichment, optimizing adsorption configuration, facilitating electron redistribution, and promoting O-O bond polarization. This collective action significantly lowered the cathodic driving force required for K2S2O8 reduction and accelerated SO4•- generation through a Lewis acid-mediated pathway, ultimately leading to a marked enhancement in cathodic ECL efficiency. As a result, the PSA-HOF/Pca-MIL-88B(Fe) composite exhibited an approximately threefold increase in ECL intensity compared with pristine PSA-HOF. Leveraging this efficient signal amplification mechanism, the developed aptasensor exhibited superior analytical performance with the assistance of PFOA aptamer, featuring a wide linear response range spanning from 10 fM to 1 μM and an ultralow detection limit of 9.8 fM, while also exhibiting outstanding stability, selectivity, and reproducibility. This work provided a robust physicochemical insight into defect-mediated co-reactant activation and paved the way for designing high-efficiency ECL emitters for environmental monitoring.