Silver Nanoparticle-Loaded 3D Pyrene-Based Covalent Organic Frameworks Combined with an Entropy-Driven Amplification Strategy for Microcystin-LR Detection

Abstract

Developing highly sensitive and stable electrochemiluminescence (ECL) biosensing platforms requires overcoming inherent limitations, such as aggregation-caused quenching (ACQ) of luminophores and coreactant-induced electrode passivation. In this work, we developed an ECL biosensor capable of detecting microcystin-LR (MC-LR) at trace levels. The system combines three-dimensional pyrene-based covalent organic frameworks (3D Py-COF) with an entropy-driven DNA cyclic amplification process, exhibiting excellent sensitivity and reliability. The unique 3D topological architecture of the Py-COF spatially isolates the pyrene nodes, effectively suppressing intermolecular π–π stacking and mitigating the ACQ effect. Furthermore, in situ-loaded silver nanoparticles (Ag NPs) serve as potent internal catalysts, facilitating potassium persulfate (K2S2O8) transformation to generate sulfate radicals (SO4•–). The design not only significantly enhances ECL emission but also mitigates electrode passivation effects. By combining the 3D Py-COF with a designed entropy-driven DNA cyclic amplification strategy, the ECL detection system achieves signal transduction and amplification driven by the synergistic action of aptamer recognition and endonuclease cleavage. The proposed biosensor greatly improved the reliability of detection, demonstrating a broad linear range spanning from 1.0 pg/mL to 100 ng/mL, with a limit of detection as low as 0.51 pg/mL. Taking advantage of strong selectivity and dependable reproducibility, the present work introduces an innovative method for precise detection of trace toxins in water systems.