Electrochemiluminescence Peptide-Based Biosensor with Hetero-Nanostructures as Coreaction Accelerator for the Ultrasensitive Determination of Tryptase.

In this work, a luminol-centric biosensor was constructed for the ultrasensitive detection of tryptase (TPS) combining dissolved O ₂ as the endogenous coreactant and Au-Ag-Pt heteronanostructures (AAPHNs) as coreaction accelerator. Dissolved O ₂ could rapidly generate superoxide anion radical (O ₂ ^•- ) with the catalysis of AAPHNs to in situ react with luminol anion radical (L ^•- ) to generate excited-state species 3-aminophthalate (AP ^2-* ) for emitting ECL signal, resulting in a remarkable "single on" state. In order to further improve the sensitivity of the sensor, we employed self-assembled DNA nanotubes (DNANTs) as a carrier to immobilize the luminophore of doxorubicin-luminol (Dox-Lu) complex. In this assay system, target tryptase could directly induce the cleavage of vasoactive intestinal peptide (VIP), which caused the ECL probe of DNANTs-Dox-Lu releasing from the electrode surface to obtain a significant "signal off" state. By changing the signal from "on" to "off", the proposed ECL peptide-based biosensor for TPS detection achieved a dynamic concentration range (2.5 pg/mL-200 ng/mL) with an extremely low detection limit of 0.81 pg/mL. This work presented a new signal amplification method for the construction of the sensor based on the luminol-dissolved O ₂ ECL system.