In the biological sciences, a multiplex assay is a type of

immunoassay An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoa ...

that uses magnetic beads to simultaneously measure multiple

analyte An analyte, component (in clinical chemistry), or chemical species is a substance or chemical constituent that is of interest in an analytical procedure. The purest substances are referred to as analytes, such as 24 karat gold, NaCl, water, etc. ...

s in a single experiment. A multiplex assay is a derivative of an

ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presen ...

using beads for binding the capture antibody. Multiplex assays are still more common in research than in clinical settings. In a multiplex assay, microspheres of designated colors are coated with antibodies of defined binding specificities. The results can be read by

flow cytometry Flow cytometry (FC) is a technique used to detect and measure physical and chemical characteristics of a population of cells or particles. In this process, a sample containing cells or particles is suspended in a fluid and injected into the flow ...

because the beads are distinguishable by fluorescent signature. The number of analytes measured is determined by the number of different bead colors. Multiplex assays within a given application area or class of technology can be further stratified based on how many analytes can be measured per assay, where "multiplex" refers to those with the highest number of analyte measurements per assay (up to millions) and "low-plex" or "mid-plex" refers to procedures that process fewer (10s to 1000s), though there are no formal guidelines for calling a procedure multi-, mid-, or low-plex based on number of analytes measured. Single-analyte assays or low-to-mid-plex procedures typically predate the rise of their multiplex versions, which often require specialized technologies or miniaturization to achieve a higher degree of parallelization.

References

{{Reflist Laboratory techniques Research methods