CuS as co-reaction accelerator in PTCA-K2S2O8 system for enhancing electrochemiluminescence behavior of PTCA and its application in detection of amyloid-β protein

In this work, 3,4,9,10-perylenetetracar-boxylic acid (PTCA) as luminophor was grafted on the surface of graphene oxide (PTCA-GO) directly. GO exhibited large specific surface area and excellent electrical conductivity which can immobilize large amounts of PTCA to improve the electrochemiluminescence (ECL) efficiency. Moreover, gold nanoparticles (Au NPs) were anchored on the surface of PTCA-GO to immobilize primary antibodies (Ab1) via Au-NH2 bond and enhance the electron transport of PTCA-GO. CuS was used as a novel co-reaction accelerator in PTCA-K2S2O8 system to label secondary antibodies (Ab2), which can react with the coreactant (K2S2O8) to produce more SO4•-. SiO2 nanospheres with large specific surface area were used to load a mass of CuS and Au NPs, which can directly combine with Ab2 and accelerate the ECL emission remarkably. Therefore, a novel sandwich-type ECL immunosensor was fabricated successfully for amyloid-β protein (Aβ) detection. Under the optimal condition, a wide detection range from 50 fg/mL to 25 ng/mL and a low detection limit of 18 fg/mL (S/N = 3) were obtained. Featuring favorable specificity, stability and reproducibility, the strategy can be a powerful analytical tool in sensitive trace detection of biomolecules in clinical analysis. •PTCA was grafted on Au@GO which improved the ECL behavior.•CuS acted as co-reaction accelerator to amplify the ECL signal.•CuS reacted with the coreactant (S2O82-) to produce more SO4•-.•Amyloid-β protein was ultrasensitively detected.