Ultrasensitive amyloid-β proteins detection based on curcumin conjugated ZnO nanoparticles quenching electrochemiluminescence behavior of luminol immobilized on Au@MoS2/Bi2S3 nanorods.

This work reported curcumin quenched electrochemiluminescence (ECL) behavior of luminol with H2O2 as coreactant. To achieve excellent ECL signal, luminol was anchored on Au functionalized MoS2/Bi2S3 nanorods (Luminol-Au@MoS2/Bi2S3), which not only exhibited super catalysis for H2O2 decomposition to enhance the ECL intensity of luminol/H2O2 system, but also offered a satisfying substrate material for grafting more Au nanoparticles via Au-S binding which was used to adsorb luminol and primary antibodies. As an antioxidant, the hydrophobicity of curcumin limited its bioavailability. Herein, curcumin was conjugated with ZnO nanomaterials (ZnO-CR) to increase its dispersity in water which can make it more bioavailable. Moreover, the possible quenching mechanism between luminol/H2O2 system and ZnO-CR was ascribed to the consumption of superoxide radical (O2•-) and energy transfer. The consumption amount of O2•- was calculated to be 1.2092 μM/mL through superoxide anion free radical detection kit. Besides, polydopamine was self-polymerized on the surface of ZnO-CR (PDA@ZnO-CR) to anchor secondary antibodies. In optimum parameter, the ECL immunosensor exhibited excellent performance for amyloid-β(Aβ) proteins detection with a wide detection range from 0.05 pg mL-1 to 10 ng mL-1 and a low detection limit of 21 fg mL-1 (S/N = 3).