Aggregation-Induced Electrochemiluminescence of Silica-Confined Tetraphenylethylene with Pd Nanocube-Loaded Co3O4 Nanosheets as a Coreaction Accelerator for Sensitive Bioanalysis

Aggregation-induced electrochemiluminescence (AIECL) provides a new approach for the development of novel electrochemiluminescence (ECL) strategies. Herein, a biosensor was constructed by incorporating 1,1,2,2-tetra(4-carboxylphenyl)ethylene (H₄TCPE) into a mesoporous silica nanosphere (MSN) to obtain a highly organized AIECL luminophore of (MSN-H₄TCPE) for signal antibody (Ab₂) labeling and using Pd nanocube (NC)-loaded Co₃O₄ nanosheets (NSs) (PdNCs/Co₃O₄NSs) as a novel coreaction accelerator. The confinement of H₄TCPE molecules in the MSN restricted the intramolecular rotation and thus enhanced the radiation transition of H₄TCPE. In addition, the PdNCs/Co₃O₄NSs exhibited efficient mutual conversion of the Co²⁺/Co³⁺ redox couple with the perfect catalytic performance of PdNCs and facilitated the decomposition of the coreactant, leading to a substantial enhancement in ECL signal. Subsequently, the localization and fixation strategy with HWRGWVC (HWR) heptapeptides as a specific antibody immobilization agent was introduced, which further maintained the biological activity of the antibody on the PdNCs/Co₃O₄NSs and MSN-H₄TCPE surface and significantly improved the incubation performance. Benefiting from the perfect sensing strategy, the obtained ECL immunosensor revealed an admirable manifestation for the precise detection of neuron-specific enolase (NSE) with a broad concentration range of 1 fg/mL to 5 ng/mL and a detection limit of 0.33 fg/mL.