Microbead (research)

Microbeads are uniform polymer particles, typically 0.5 to 500 micrometres in diameter. Bio-reactive molecules can be absorbed or coupled to their surface, and used to separate biological materials such as cells, proteins, or nucleic acids.

Microbeads have been 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.

Microbeads were created when John Ugelstad managed to form polystyrene beads of the same spherical sizes at the University of Trondheim, Norway in 1976. He created superparamagnetic microbeads (Dynabeads), which exhibit magnetic properties when placed in a magnetic field. When they are removed from the magnetic field, there is no residual magnetism, which led to the development of magnetic separation technology. Other processes such as centrifugation, filtration, columns or precipitation, are not needed.

Microbeads display a large surface area per volume. This together with uniformity of size and shape provides for very good accessibility and fast liquid-phase reaction kinetics, and rapid and efficient binding.

Black polyethylene microspheres can have magnetic or conductive functionality, and have uses in electronic devices, EMI shielding and microscopy techniques.

Fluorescent polyethylene microspheres are commonly used to run blind tests on laboratory and industrial processes, in order to develop proper methods and minimize cross-contamination of equipment and materials. Microspheres that appear to be invisible in the daylight can be illuminated to display a bright fluorescent response under UV light.

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