Introducing AgNPs-VB composites as the dual signal quenching of CeO-AuNPs-g-CNQDs hybrids for ultrasensitive "on-off" electrochemiluminescence immunosensing of prostate specific antigen.

An ultrasensitive resonance energy transfer based "on-off" switch electrochemiluminescence (ECL) immunosensing strategy was proposed and applied for prostate specific antigen (PSA) detection. In detail, self-enhancing nanohybrids of nano-CeO and AuNPs decorated graphitic carbon nitride quantum dots (CeO-AuNPs-g-CNQDs) were synthesized, which produced high ECL emission with coreactant KSO for "switch-on" state. Noticeably, due to the reversible Ce↔ Ce reaction, nano-CeO could serve as highly-efficient coreaction accelerator and induce the decomposition of SO into SO, which endowed the g-CNQDs/KSO system with enhanced ECL emission. Moreover, AuNPs acted crucial role in promoting the electronic transmission rate and providing sites to immobilize the biomolecules. On the other hand, the AgNPs-VB nanocomposites were used as dual labels to quench the ECL signal of g-CNQDs-KSO system via ECL-RET, leading to the decreased ECL for "switch-off" state. On the basis of sandwich-typed immunosensing strategy, the developed ECL immunosensing platform exhibited sensitive response to PSA in a linear range of 1.0 × 10 50 ng mL with a low detection limit of 0.0045 pg mL (S/N = 3). This work provided a promising tool in early clinical diagnostics of prostate cancer.