Immunoassay by hydride generation-atomic fluorescence spectrometer using arsenic absorbed Fe 3 O 4 @Au nanoparticles as label

A novel immunoassay method based on hydride generation-atomic fluoresce spectrometer (HG-AFS) with arsenic (As) absorbed Fe 3 O 4 @Au (Fe 3 O 4 @Au-As) nanoparticles as tags to the antibody for the rapid and early diagnosis of α-fetoprotein (AFP) in primary carcinoma of the liver is proposed. The new approach combined the use of Fe 3 O 4 @Au-As nanoparticles labeled antibody, and HG-AFS detection for sandwich-type immunoassay. Firstly, Fe 3 O 4 @Au-As nanoparticles were prepared. Then Fe 3 O 4 @Au-As composite is used to immoblize HRP-labeled anti-AFP as secondary antibody (bionanospheres). The bionanospheres were characterized by transmission electron microscopy (TEM), and ultraviolet visible spectroscopy (UV-Vis). Sandwich-type protocol was successfully introduced to develop a new high-efficiency HG-AFS immunoassay. An important advantage of HG-AFS is high sensitivity to the detection of As. And in the immune-complex the concentration of As is high and has a linear relationship with AFP antigen, which could enlarge the signals. The antigen concentration, thus, was determined by measuring the arsenic in the immune complex with HG-AFS, which is quite promising for the detection of low concentration AFP at early stage of primary carcinoma of the liver.