| abstract |
The invention relates to novel competitive immunoassays that are useful in detecting and quantitatively measuring analytes down to the nanomolar range. The invention also includes methods of selecting antibodies from libraries of polypeptides expressed on a cell surface. In conducting immunoassays, anti-analyte antibody molecules are expressed on the surface of a bacterial cell and then used to bind with labeled analyte. Quantitation is performed by competitively displacing the bound labeled analyte with a known amount of analyte and measuring the label. The method is rapid and inexpensive and may be performed with readily available safe labeling reagents such as fluorescent compounds. |