Bio-Rad Bio-Plex Pro™ TGF-β Assays - Manual (Page 4)

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Principle
Technology
The Bio-Plex ® multiplex system is built upon the three core elements of
xMAP technology:
n
Fluorescently dyed microspheres (also called beads), each with a distinct
color code or spectral address to permit discrimination of individual
tests within a multiplex suspension. This allows simultaneous detection
of up to 500 different types of molecules in a single well of the 96-well
microplate on the Bio-Plex
® 3D system, up to 100 different types of
molecules on the Bio-Plex ® 200 system, and up to 50 different types
of molecules on the Bio-Plex ® MAGPIX ™ system
n
On the Bio-Plex 200 and Bio-Plex 3D systems, a dedicated flow
cytometer with two lasers and associated optics to measure the
different molecules bound to the surface of the beads. In the
Bio-Plex MAGPIX, the entire sample load volume is injected into a
chamber where the beads are imaged using LED and CCD technology
n
A high-speed digital signal processor that efficiently manages the
fluorescence data
Assay Format
Bio-Plex Pro ™ assays are essentially immunoassays formatted on
magnetic beads. The assay principle is similar to that of a sandwich
ELISA (Figure 1). Capture antibodies directed against the desired
biomarker are covalently coupled to the beads. Coupled beads react
with the sample containing the biomarker of interest. After a series of
washes to remove unbound protein, a biotinylated detection antibody
is added to create a sandwich complex. The final detection complex is
formed with the addition of streptavidin-phycoerythrin (SA-PE) conjugate.
Phycoerythrin serves as a fluorescent indicator or reporter.