Luminex immunoassays employ xMAP technology to detect a broad range of nucleic acids and proteins in complex biological matrices. The Luminex assays follow the ELISA assay principle. This means they have similar protocols compared to ELISA analysis. Besides being a Luminex ELISA multiplex assay, they can simultaneously detect up to 500 analytes in a single assay run. Multiplexing capacities help assays such as ELISA and Luminex to analyze multiple biomarkers or other target analytes in a single reaction. Hence, Luminex ELISA assays are used widely in biomedical and pharmaceutical sciences.
xMAP technology
The Luminex ELISA xMAP technology uses fluorescently labeled microspheres to detect multiple analytes in a single assay reaction. As each of the microspheres has a low density and is smaller in size, they exhibit faster assay kinetics.
xMAP is multi-analyte profiling, where “x” represents the target analyte. These analytes can include nucleic acids, proteins, or polysaccharides. Moreover, the xMAP beads come in MicroPlex and MagPlex formats. Each bead is read through an xMAP instrument. Thus, Luminex assays have several advantages, requiring small sample volumes, savingreagents and time, testing multiple analytes, developing custom assays, and much more.
Low-cost Luminex assay instruments
Luminex assays have several instruments to meet all research budgets and requirements. Luminex combines multiple lasers and faster digital signal processors to rapidly identify bead regions based on unique spectral signatures for quantifying individual analytes. The assay provides multiple readings per bead set and ensures robust assay statistics. Luminex instruments fall under two technologies; fluorescence-based (MAGPIX) and flow-cytometry-based (Luminex 200™, FLEXMAP 3D, and xMAP INTELLIFLEX). Let us dive deep into each of these Luminex instruments.
In MAGPIX Luminex systems, activated magnetic microspheres are subjected through an imaging chamber, where a specific magnet captures them for optical analysis. A 635nm red LED excites the fluorescent component of the microsphere, while another 525nm green LED excites the reporter molecule. The imager present in the MAGPIX instrument detects the bead region and measures the generated signal. MAGPIX systems are simple, portable, and affordable Luminex instruments. Besides, they can multiplex up to 50 target analytes per well.
The Luminex 200, FLEXMAP 3D, and xMAP INTELLIFLEX systems employ lasers to assess beads individually through a rapidly flowing fluid stream. Similar to MAGPIX systems, a red diode excites the fluorescence dyes while the green laser excites the reporter molecule. Optical processors detect the bead region and quantify the generated signal.
Luminex 200 instruments are gold standards for multiplexing. They can analyze upto 100 target analytes per well. On the other hand, the FLEXMAP 3D instrument is a flexible platform with high throughput and high-multiplexing capabilities. They can analyze up to 500 target analytes in a single assay well. Finally, xMAP INTELLIFLEX is the most versatile Luminex platform.
Also Read: What Can LC-MS Analysis Detect?
Along with multiplexing capacities of up to 500 analytes per well, the xMAP INTELLIFLEX instrument has an additional 405nm violet laser that excites a secondary reporter molecule. This optional violet laser enables a unique dual reporting feature that empowers researchers to double their data by acquiring two parameters per target.
