A ternary quenching electrochemiluminescence insulin immunosensor based on Mn released from MnO@Carbon core-shell nanospheres with ascorbic acid quenching AuPdPt-MoS@TiO enhanced luminol.

This work reported a ternary quenching strategy based on electrochemiluminescence resonance energy transfer (ECL-RET) between luminol/HO system and MnO capped carbon nanospheres (MnO@C) and Mn released from the reduction of MnO and ascorbic acid (AA) consumed superoxide radical (O) for detection of insulin. To improve the ECL behavior of luminol, AuPdPt hybrid nanoparticles decorated MoS nanosheet-coated TiO nanobelt (AuPdPt-MoS@TiO) were applied to combine with luminol and primary antibodies via covalent linkage which exhibited perfectly catalysis for the electroreduction of HO. In order to sensitively detect insulin, labels MnO@C were used to anchor secondary antibodies via electrostatic interaction and inhibit the ECL intensity of luminol. The perfect overlap of the ECL spectrum of luminol with the absorption spectrum of MnO allowed the ECL-RET to decrease ECL signals of luminol. Specifically, AA was introduced not only to inhibit the ECL of luminol, but also to reduce MnO producing Mn which can be reacted with O to further quench the ECL reaction between luminol and HO. On the basis of the dual quenching effect of luminol, the sandwich immunosensor was prepared to determine insulin with wide linear range from 0.5 pg mL to 60 ng mL and a low detection limit of 0.13 pg mL (S/N = 3).