A cost-effective alternative to ELISAs and other platforms is multiplexing, which utilizes our MAGPIX CCD imager. The basis of a multiplex is antibody-coated microparticles, rather than antibody-coated microplates as with a traditional ELISA. Each microparticle is coated with one type of antibody and a ratio of fluorophores (i.e., dye) that tells the MAGPIX what kind of microparticle it is (i.e., one coated with IL-6 responsive antibodies). Using a series of washes and additions, a microparticle-antibody-analyte-antibody-conjugate chain is created using streptavidin-phycoerythrin as a fluorescent enzyme. Once loaded onto the MAGPIX, each sample well is assessed by the machine – first an LED excites the fluorophores to establish what kind of microparticle it is (i.e., one for IL-6), and then another LED excites the streptavidin-phycoerythrin, measuring the response with a CCD camera, and compares it to a standard curve to establish a concentration.

The primary benefit of multiplexing lies in the ability to distinguish one type of microparticle from another, which in turn allows for multiple types of microparticles to be added to the same sample. Using a 12-PLEX will give you results for 12 different analytes with the use of only 125 µL of sample. Additionally, multiplexing is remarkably cheap as compared to a panel of ELISAs. The first analyte purchased in a PLEX includes all consumables needed to run the plate, such as a mylar plate and reagents, in addition to microparticles and conjugate specific to that analyte. Cost-savings begin on the second analyte (as compared to purchasing two ELISAs), as only microparticle and conjugate need be obtained for any analytes past the first.

View R&D System’s Multiplex Building Tool.