Assay

Assay

If the procedure of the detection reaction of an analyte is standardized, so-called assays are used in molecular biology. In this case, the evidence of DNA and DNA-binding proteins, RNA, proteins and viruses can be distinguished. Although there is a broad spectrum of assays, they usually have the following steps in common: sample processing and manipulation, analyte-specific discrimination or identification, signal or analyte amplification, signal detection and interpretation, and signal amplification and improvement (reduction of the background signal by filters).

Depending on the time of measurement, a distinction is made between endpoint assays and kinetic assays. The number of detectable analytes allows subdivision of assays in single-target assays and multiplex assays. Similarly, categorization by outcome type is possible in qualitative assays, semi-quantitative assays, quantitative assays, and functional assays. With respect to the sample type, a distinction is made between bioassays, ligand binding assays and immunoassays. Some examples of detection systems that can be used in constructing an assay are photometry, turbidimetry, nephelometry, reflectometry, and cytometry.

Known assays include the DNAse footprinting assay, the electrophoretic mobility shift assay, the Bradford test, the Lowry test, ELISA, the enzyme-linked fluorescence assay (ELFA), and the electrochemiluminescent immunoassay (ECLIA).