Abstract
A colorimetric immunoassay of the present invention uses nanostructured material with high absorption and high scattering ability as a label material for biosensors. Subject matters to be measured may be characterized or quantified by determining the changes in optical properties of the nanostructured material. The biosensor of the present invention may be operated in broad light wavelength range and detected by direct observation with naked eye. The biosensor of the present invention may be also provided with advantages such as higher sensitivity and lower cost.