High sensitivity antigen detection by fluorescence anisotropy decay immunosensor

Immunosensor is an ideal kind of biosensor, which enables highly specific detection of any kind of biological molecules. However, in spite of long and intensive efforts of research and development, no immunosensor is in practical use. This is mainly because of the difficulty in reduction of the back ground noise of non-specific adsorption. In this study, fluorescence anisotropy decay principle was employed to avoide the disturbance of non-specific adsorption. Fluorescent labeled antibody, with Pyrene derivative, was immobilized on the surface of quartz substrate. Fluorescence anisotropy of immobilized antibody was measured by evanescent excitation stage. Antigen solution was administrated on the surface of the substrate and antigen antibody binding was detected as fluorescence anisotropy change. Detection of antigen at the concentration of as low as 100 fg/mL was demonstrated.