An electrochemical immunosensor for ultrasensitive detection of carbohydrate antigen 199 based on Au@CuxOS yolk–shell nanostructures with porous shells as labels.

A novel and sensitive electrochemical immunosensor for ultrasensitive detection of pancreatic cancer biomarker carbohydrate antigen 199 (CA199) was proposed by using Au@Cu x OS yolk–shell nanostructures with porous shells as labels for signal amplification. Au@Cu x OS yolk–shell nanostructures exhibit high electrocatalytic activity toward the reduction of hydrogen peroxide (H 2 O 2 ) as analytical signal. Moreover, secondary antibody (Ab 2 ) can adsorb on the surface of Au@Cu x OS with porous shells which has large surface area and could greatly increase the probability of Ab 2 –antigen interactions thereby leading to higher sensitivity. Reduced graphene oxide–tetraethylene pentamine (rGO–TEPA), containing abundant amine groups, was supported Au nanoparticles as a support platform to immobilize the primary antibody (Ab 1 ). The resulting sensing interface of rGO–TEPA/AuNPs could provide a large electroconductive surface area, allowing high loadings of the biological recognition elements as well as the occurrence of electrocatalytic and electron-transfer processes. Under optimal conditions, the immunosensor exhibited a wide linear response to CA199 ranging from 0.001 to 12 U/mL with a low detection limit of 0.0005 U/mL. The designed immunosensor displayed good precision, high sensitivity, acceptable stability and reproducibility, and has been applied to the analysis of serum with satisfactory results. The proposed method provides a new promising platform of clinical immunoassay for other biomolecules. [ABSTRACT FROM AUTHOR]