Noncompetitive immunoassays for small molecules with high sensitivity and specificity

Abstract

Publisher Summary Immunoassays techniques are widely used for trace characterization of physiologically active substances with a low molecular weight. These techniques exhibit excellent specificity and feasibility along with higher sensitivity than other common analytical methods used in this field. Noncompetitive assays, also known as immunometric assays, are essentially classified as two-site immunometric assays and single-antibody immunometric assays. The common feature of these assays is the reaction of analyte versus excess amount of antibodies. It is noted that noncompetitive immunoassays are considered more sensitive than competitive assays, an advantage that is exhibited by mathematical modeling. Noncompetitive assays measure the analyte bound sites, while the competitive assays determine the analyte-unbound sites. The antigen-specific antibodies are often directly labeled with the signal-generating group to allow simple and sensitive measurement of the antigen-antibody complex. Noncompetitive assays also demonstrate an additional advantage of higher precision and wider working range, both of which are because of the use of excess antibody.