▎ 摘　　要

The platinum-gold (PtAu)/reduced graphene oxide (rGO) nanocomposites were obtained via the gamma irradiation assisted by microemulsion while PtAu NPs showed the monodispersed flower-like shape with small-sized (below 15 nm). Gamma irradiation controlled the reduction of graphene oxide and PtAu NPs meanwhile the microemulsion endowed PtAu NPs with porous monodisperse flower-like structure and inhibited the agglomeration of nanoparticles. The size of PtAu NPs was limited by confinement effects of graphene oxide and fragmentation ability of gamma irradiation. An ultra-sensitive, label-free immunosensor was developed on the base of above rGO supported PtAu alloy nanoparticles for the determination of carcinoma embryonic antigen (CEA). The flower-like PtAu/rGO nanocomposites had a higher faradaic current than other nanocomposites, and the obtained PtAu NPs/rGO nanocomposites not only improve the electrocatalytic activity and increase the electrode surface area in nanoscale dimension, but also provide a stable and biocompatible matrix for the convenient conjugation of antibody, thus providing a high-efficiency immunoassay platform. The developed immunosensor showed excellent performance for the detection of CEA with a low detection limit of 7 fg.mL(-1) and a wide dynamic range from 10 fg.mL(-1) to 1x10(8) fg.mL(-1). In addition, the immunosensor system showed high specificity with the interference of ascorbic acid, bovine serum albumin, L-tryptophan and alpha fetal protein. The contribution of this work lies in the research of the synergistic effect of gamma irradiation and microemulsion in the formation of flower-like PtAu NPs/rGO nanoparticles applied in preparation of immunosensor. In view of the versatility of self-assembled nanoparticles, this strategy has great application prospects in fabrication of immunosensors and other biological devices.