Dynabeads

Dynabeads are superparamagnetic spherical polymer particles with a uniform size and a consistent, defined surface for the adsorption or coupling of various bioreactive molecules or cells.

Dynabeads were developed after John Ugelstad managed to create uniform polystyrene spherical beads (defined as microbeads) of exactly the same size,^[1][2] at the University of Trondheim, Norway in 1976, something otherwise only achieved by NASA^[3] in the weightless conditions of SkyLab. Dynabeads are typically 1 to 5 micrometers in diameter. This is in contrast to the Magnetic-activated cell sorting beads, which are approximately 50 nm.

This discovery revolutionised the liquid-phase kinetic separation of many biological materials.^[3] The technology behind the beads, called Dynabeads, was licensed to Dyno Industrier in 1980 and this magnetic separation technology has been since used for the isolation and manipulation of biological material, including cells, nucleic acids, proteins and pathogenic microorganisms.^[4][5] The uniformity in size, shape, and surface area allow for reproducibility and help to minimize chemical agglutination.

Dynabeads are frequently used for cell isolation.^[4][6] Cell-types often of interest to purify may be specific leukocytes, such as CD4+ T cells, stem cells,^[7] or circulating tumor cells (CTCs). Dynabeads may be covalently linked to an antibody that recognizes a specific protein on the surface of the target cell-type. Alternatively, Dynabeads may attach to the cell indirectly, either via streptavidin on the Dynabead linking to a biotinylated primary antibody, or a secondary antibody on the Dynabead linking to the primary antibody. Streptavidin linkage to the primary antibody allows Dynabeads to capture cells with lower expression of the surface protein.^[8]

Following a series of mergers and acquisitions, Dynal and Dynabeads are currently owned and produced by Invitrogen,^[4] part of Life Technologies.

See also

• Flow cytometry
• Magnetic-activated cell sorting

References

1. ↑ J. Ugelstad & F.K. Hansen, Rubber Chem. and Techn. 49, 536 - 609 (1976). "Kinetics and mechanism of emulsion polymerization."
2. ↑ "Abstract of Cell Isolation and Expansion Using Dynabeads ". Springer. 
3. ↑ 3.0 3.1 "The History of Dynal and Biomagnetic Separation". Invitrogen. 
4. ↑ 4.0 4.1 4.2 "Cell Isolation & Expansion". Invitrogen. 
5. ↑ "References for protein isolation applications using Dynabeads". Invitrogen. 
6. ↑ Immunomagnetic cell sorting--pushing the limits. Thiel A, Scheffold A, Radbruch A. Immunotechnology. 1998 Oct;4(2):89-96. Review. PMID:9853950
7. ↑ Multicentre European study comparing selection techniques for the isolation of CD34+ cells. de Wynter EA, Ryder D, Lanza F, Nadali G, Johnsen H, Denning-Kendall P, Thing-Mortensen B, Silvestri F, Testa NG. Bone Marrow Transplant. 1999 Jun;23(11):1191-6
8. ↑ Cancer Res. 2013 Apr 1;73(7):2310-21. doi: 10.1158/0008-5472.CAN-12-2956. Epub 2013 Feb 1.Cholesterol loading and ultrastable protein interactions determine the level of tumor marker required for optimal isolation of cancer cells.Jain J, Veggiani G, Howarth M.

Further reading

• Ashok Kumar, Igor Yu Galaev, Bo Mattiasson (2007). Cell separation: fundamentals, analytical and preparative methods. Springer. ISBN 978-3-540-75262-2.