Basic principles of ELISA

To date, the commonest type of immunoassay is the enzyme-linked immunosorbent assay (ELISA). The ELISA technique was developed through the pioneering work of Engvall and Perlmann in the 1970s. By immobilizing the reagents to a surface, the facile separation of bound and unbound material is achieved, making ELISA a powerful tool for the measurement of analytes in crude sample preparations.ELISA has become the basic immunoassay on which many of the modern assay formats are based. 

Calibration standards can be included in the ELISA experiment to produce a sigmoidal standard curve, and can provide the means to quantify the extent of the binding event and hence, the amount of target analyte present in an unknown sample. ELISAs can be employed as quantitative screening assays, depending on the particular performance characteristics of the assay and assuming the use of adequate control samples. 

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