Development of POC optical immunosensor based upon the fluorescence anisotropy measurement

The blood test is a routine procedure in medical diagnosis. However it takes a couple of days to get the results because blood samples are analyzed by sending to the specialized facility because the operation of the blood test instrument is costly for a hospital or clinic. So development of a novel low cost blood test device is an important issue considering the burden of the patient. To developing a low cost and instant diagnosis system, various immunosensor have been studied because of it´s quick response and application of micro fabrication. But background noise by the surface adsorption reduces the S/N ratio, and practical use of the immunosensor isn´t possible for now. So we tried to detect antigen-antibody reaction by fluorescence anisotropy in this study. Fluorescence anisotropy retains the information of the rotational motion of antibody molecules. As the antigen bounds to the antibody, the degrees of rotational freedom are reduced and the antigen-antibody reaction can be detected by the shift of fluorescence anisotropy. In principle fluorescence anisotropy is not affected by the nonspecific surface adsorption. A micro optical immunosensor was fabricated. Detection of anisotropy change by the antigen-antibody reaction was demonstrated with the device. For higher S/N ratio observation, evanescent excitation system was also developed.