Problem: As more analytes are discovered, more tests are required per biological sample for drug discovery, research analysis and diagnostic testing. However, an unlimited amount of sample is never available. Small volumes of precious sample limit the number of tests that can be performed, which can hinder diagnosis and discovery.

The Luminex MAGPIX system.

Solution: Multiplex testing, the simultaneous analysis of multiple analytes from the same sample, has quickly become the standard to conserve precious sample. The Luminex ® xMAP® platform uses differentially dyed microspheres of the same size to achieve multi-analyte profiling for proteins and nucleic acids. The key drivers for adoption include cost savings, labor efficiencies, sample conservation, work flow efficiencies, sensitivity and dynamic range. The versatility of the platform is evidenced by greater than 7,000 peerreviewed publications. The breadth of bioanalytical applications includes hundreds of commercially available analytes and a vast number of custom assays developed for a global installed base of more than 7,000 instruments.

The configuration of an xMAP assay consists of a suspension array where specific capture moieties are covalently coupled to the surfaces of internally dyed microspheres (beads). After completion of assay incubations with a detection reagent, the beads are separated within a Luminex analyzer and interrogated with two lasers or LEDs—one for classification of the bead identity (region), and the other for quantification of bound reporter fluorophore.

Several varieties of fluorescent microspheres are available from Luminex. MagPlex® Microspheres are superparamagnetic beads functionalized with surface carboxyl groups for covalent attachment of ligands. MicroPlex® Microspheres are polystyrene beads also functionalized with surface carboxyl groups. LumAvidin ® Microspheres contain a surface layer of avidin for binding biotinylated ligands and are useful for attachment of small molecules or peptides. SeroMAP™ Microspheres are carboxylated beads which reduce nonspecific binding and perform well in serological applications. MagPlex- TAG Microspheres use Luminex’s proprietary xTAG® Technology with MagPlex Microspheres to facilitate the development of custom nucleic acid detection assays.

There are currently two flow cytometry- based instruments, the Luminex® 100/200™ and the FLEXMAP 3D®; and one flow cell-LED/CCD-based instrument, the MAGPIX®, available from Luminex or through its partners. Each only require a few microliters of sample in a 20 to 200 μL reaction, thus the instruments are well-suited for applications where sample size is limited.

The MAGPIX utilizes a flow cell and robust LED/CCD-based optics which supports multiplexing of up to 50 tests in a single reaction volume using MagPlex or MagPlex-TAG beads. At a low cost and compact size, MAGPIX provides an affordable multiplexing solution ideal for research laboratories and remote laboratory testing sites.

The Luminex 100/200 allows multiplex analysis of up to 100 analytes per reaction. The system is versatile and can be used for a variety of applications such as immunoassays, genotyping, gene expression and enzymatic assays. Robust optics and fluidics afford quantitative results over a 3-4 log dynamic range with strong concordance to enzyme-linked immunosorbent assay (ELISA) and mass spectrometry.

The FLEXMAP 3D enhanced optics permit multiplexing of up to 500 analytes per well and provide improved sensitivity with dynamic range extended to 4.5 logs. The system is compatible with both 96-well and 384-well plates and has a piercing probe which allows sealed plates to be analyzed. The dual syringe configuration processes plates 2 to 3 times faster than the Luminex 100/200. The FLEXMAP 3D is an ideal platform for multiplexing analytes that may have broadly dissimilar levels.

Multiplex testing has quickly become the standard in drug discovery, research analysis and diagnostic testing. The key drivers for adoption include cost savings, labor efficiencies, sample conservation, work flow efficiencies, sensitivity and dynamic range.

For more information, go to: www.luminexcorp.com