PARTICLE DIFFRACTION ASSAY

摘要

Methods and apparatus are provided for detecting analyte in a sample using diffraction patterns. In the subject method, sample suspected of comprising analyte and particles if the analyte is not the particle, as well specific binding pair members, are combined in an assay medium with a solid surface transparent to a wavelength range of interest. In one embodiment, a cross-linking agent is included in the assay medium, where the particles cross-link in an amount proportional to the amount of analyte in the sample. As the particles interact with analyte and specific binding pair members, larger diffraction particles are formed which are randomly distributed in a single plane in the assay medium. The diffraction particles may remain mobile in solution or may settle on the solid surface. In an alternative embodiment, the solid surface comprises members of a specific binding pair which are randomly distributed, providing for specific binding of the diffraction particles to the surface. The diffraction particles are then irradiated with coherent light, where the light is diffracted into a diffraction pattern by the diffraction particles. The spacing and amplitude of the diffraction pattern is detected and measured. A logic means is used to relate the spacing and amplitude of the diffraction pattern to the presence of analyte in the sample.