A ternary quenching electrochemiluminescence insulin immunosensor based on Mn2+ released from MnO2@Carbon core-shell nanospheres with ascorbic acid quenching AuPdPt-MoS2@TiO2 enhanced luminol.

Abstract

This work reported a ternary quenching strategy based on electrochemiluminescence resonance energy transfer (ECL-RET) between luminol/H2O2 system and MnO2 capped carbon nanospheres (MnO2@C) and Mn2+ released from the reduction of MnO2 and ascorbic acid (AA) consumed superoxide radical (O2•-) for detection of insulin. To improve the ECL behavior of luminol, AuPdPt hybrid nanoparticles decorated MoS2 nanosheet-coated TiO2 nanobelt (AuPdPt-MoS2@TiO2) were applied to combine with luminol and primary antibodies via covalent linkage which exhibited perfectly catalysis for the electroreduction of H2O2. In order to sensitively detect insulin, labels MnO2@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 MnO2 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 MnO2 producing Mn2+ which can be reacted with O2•- to further quench the ECL reaction between luminol and H2O2. 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\u202fpg\u202fmL-1 to 60\u202fng\u202fmL-1 and a low detection limit of 0.13\u202fpg\u202fmL-1 (S/N\u202f=\u202f3).