Chapter 18 - Applications Of Spectrophotometry

Question 1

What are immunoassays and how do they work?

Answer 1

An enzyme linked immunosorbent assay (ELISA) employs antibodies to detect analyte. Antibody1 is specific for the analyte of interest and is bound to a polymer support and treated with unknown. After excess unbound molecules have been washed away, the analyte remains bound to antibody 1. The bound analyte is then treated with antibody 2 which recognizes a different site on the analyte and to which an enzyme is covalently attached. Enzyme bound to antibody 2 can catalyze reactions that produce coloured or fluorescent products. Each molecule of analyte bound in the immunoassay leads to many molecules of coloured or fluorescent product that are easily measured.