Glucose oxidase-encapsulated nanogold hollow microspheres as labels based on a sensitive electroluminescent immunoassay

We herein report the synthesis of glucose oxidase-encapsulated nanogold hollow microspheres (GOx-GHS), which show excellent catalytic performance for the reduction reaction of glucose, and the nanogold on the GOx-GHS provided the nanoparticles with good biocompatibility. In addition, the electrochemiluminescence (ECL) property of luminol was investigated and a type of luminol nano-composite (AuNPs-EGN-luminol) was prepared. The as-prepared nano-composite was found to have good ECL property of the luminol, as well as good electroconductibility. The prepared GOx-GHS and AuNPs-EGN-luminol were applied in a sandwich-type ECL immunosensor for cancer antigen 125 (CA125). In the immunosensor, AuNPs-EGN-luminol acted as a solid support for CA125 primary antibody, and GOx-GHS was employed as the supporter of CA 125 secondary antibody. With the addition of glucose, the hydrogen peroxide was prepared and the ECL property of the AuNPs-EGN-luminol was enhanced. The proposed immunosensor enabled CA125 concentrations to be determined in the range of 1 pg mL −1 to 100 ng mL −1 , with a detection limit of 0.38 pg mL −1 . We herein report the synthesis of glucose oxidase-encapsulated nanogold hollow microspheres (GOx-GHS), which show excellent catalytic performance for the reduction reaction of glucose.