Introducing AgNPs-VB2 composites as the dual signal quenching of CeO2–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 2 and AuNPs decorated graphitic carbon nitride quantum dots (CeO 2 –AuNPs–g-CNQDs) were synthesized, which produced high ECL emission with coreactant K 2 S 2 O 8 for “switch-on” state. Noticeably, due to the reversible Ce 3+ ↔ Ce 4+ reaction, nano-CeO 2 could serve as highly-efficient coreaction accelerator and induce the decomposition of S 2 O 8 2− into SO 4 • - , which endowed the g-CNQDs/K 2 S 2 O 8 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 2 nanocomposites were used as dual labels to quench the ECL signal of g-CNQDs-K 2 S 2 O 8 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 −5 _ 50 ng mL −1 with a low detection limit of 0.0045 pg mL −1 ( S/N  = 3). This work provided a promising tool in early clinical diagnostics of prostate cancer.