Bio-Rad's Bio-Plex® suspension array system, xMAP technology overview

Abstract

The Bio-Plex(®) system utilizes xMAP technology to permit the multiplexing of up to 100 different analytes. Multiplex analysis gives researchers the ability to look at analytes simultaneously providing more information from less sample volume in less time than traditional immunoassay methods. Similar to ELISA, xMAP utilizes an antibody sandwich for detection but differs from ELISA in capture substrate and detection method. Rather than a flat surface, Bio-Plex(®) assays make use of differentially detectable bead sets as a substrate capturing analytes in solution and employs fluorescent methods for detection. These bead sets identify the analytes and detection antibodies are used to measure the quantity of analyte. The use of differentially detectable beads enables the simultaneous identification and quantification of many analytes in the same sample.

Figure 1

Multiplex immunoassay technology. Beads are colored internally with two different fluorescent dyes (red and infrared). Ten different concentrations of red and infrared dyes are used to generate 100 distinct bead regions. Each bead region is conjugated to a specific target analyte.

Figure 2

Data acquisition and reduction. Dyed beads are pushed through a detection chamber in a single file. The red classification laser (635 nm) interrogates internal dye to identify bead regions. The green reporter laser (532 nm) interrogates fluorescent reporter to measure analyte concentration.

Figure 3

Immobilized magnetic beads illuminated with LED’s and imaged using CCD technology.

Figure 4

xMAP workflow.

Figure 5

Magnetic bead architecture.

Figure 6

Hands-free washing and separation of magnetic beads.

Figure 7

Visualization of sample relationships by analyte using Bio-Plex® Data Pro Software.