Electrochemiluminescence biosensor based on gold nanoparticles modulated cathode AIE-activated metal-organic...

In traditional metal-organic framework (MOF) electrochemiluminescence (ECL) systems, the organic luminescent ligands commonly exhibit aggregation-induced quenching (ACQ), which restricts both the efficiency and detection sensitivity of ECL. In this study, we employed the aggregation-induced emission (AIE) luminescent material 4',4″,4‴,4‴'-(ethene-1,1,2,2-tetrayl)tetrabiphenyl-4-carboxylic acid (H₄ETTC) as a ligand and successfully synthesized a highly efficient ECL emitter (named as PCN-94) via a straightforward hydrothermal reaction. Compared to H₄ETTC monomer, PCN-94 had better ECL emission, mainly due to the ECL enhancement induced by the framework. However, the luminescence of individual metal-organic framework (MOF) was unstable. To address this problem, the cathode aggregation-induced electrochemiluminescence (AIECL) performance of MOF was modulated by synthesizing two different sizes of gold nanoparticles (Au NPs). Through the tests of ultraviolet-visible (UV-vis) absorption and ECL spectra and the simulation of density functional theory (DFT) calculation, it was found that Au NPs with the size of 20 nm can enhance and stabilize the luminescence of PCN-94. On this basis, a novel "on-off" ECL biosensor was constructed, using PCN-94 as the energy donor and Fe-MIL-88 as the energy acceptor, which realized the ultra-sensitive detection of CA15-3. Therefore, this study provided a simple and effective strategy to improve the stability of AIECL materials by adjusting the size of Au NPs, which laid a solid foundation for the subsequent development and practical applications of high-performance biosensors.