Microbeads are uniform polymer particles, typically 0.5 to 500 micrometres in diameter. Bio-reactive molecules can be adsorbed or coupled to their surface, and used to separate biological materials such as cells, proteins, or nucleic acids.
Microbeads are used for isolation and handling of specific material or molecules, as well as for analyzing sensitive molecules, or those that are in low abundance, e.g. in miniaturized and automated settings.
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Microbeads were created when the late Dr. John Ugelstad managed to form polystyrene beads of the same spherical sizes at the University of Trondheim, Norway in 1976. He then created superparamagnetic microbeads (Dynabeads). These beads exhibit magnetic properties when placed in a magnetic field, with no residual magnetism when removed from the magnetic field, thereby leading to the development of magnetic separation technology.
Microbeads enable fast liquid-phase kinetics, and displays a large surface area per volume. Microbeads can execute rapid separation throughout the application protocol by applying a magnet. Other processes such as centrifugation, filtration, columns or precipitation, are not needed.
John Ugelstad was able to develop a method to create uniformly sized microbeads. Polystyrene material was crafted to produce monosized spherical beads. Uniformity of size, shape and surface area provides optimal accessibility and reaction kinetics, for rapid and efficient binding.
Microbeads serve as the main tool for bio-magnetic separations. A range of patented processes and applications have been developed based on the use of microbeads in academic and industrial research. Microbeads are pre-coupled with a ligand; a biomolecule such as antibody, streptavidin, protein, antigen, DNA/RNA or other molecule. There are three steps involved in the magnetic separation process:
Microbeads are used for cell isolation and cell expansion. Proteins and protein complexes can be separated, e.g in immunoprecipitation protocols. Molecular studies and diagnostics also benefit from microbeads (e.g immunoassay IVD and nucleic acid IVD). When microbeads are coupled with streptavidin, they offer a very efficient way to isolate any biotinylated molecule. This is frequently used in DNA/RNA binding protein studies, sequencing, and to prepare single stranded templates. Gene expression analysis also benefits from microbeads, such as isolating mRNA for transcriptional analysis.
There are many uses for microbeads, mostly for biotechnology and biomedical research. Microbeads and magnetic separation technology have enabled a range of innovative methods to benefit research on disease prevention, medicine, and other fields to improve the human condition.