Magnetic beads

The magnetic beads are superparamagnetic spherical polymer particles with a uniform size and a consistent, defined surface for the adsorption or coupling of various bioreactive molecules, such as antibodies, or cells, depending on the size of the beads.

They are a very useful tool for separation procedures, such as cell sorting or chromatin immunoprecipitation techniques such as ChIP-exo.

Basically, the magnetic beads are bound to the bioreactive biomolecules, normally antibodies, that are at the same time bound to the specific target compound (Figure 1A). By using magnets, molecules bound to the beads can be separated from others and retained in the tube while performing washing steps (Figure 1B).

Example of magnetic beads used in ChIP-exo technique

Figure 1. Magnetic beads in ChIP-exo technique. A) The magnetic bead is bound to the antibody that has been previously coupled to the protein-DNA complex. B) The magnetic rack allows the retention of the molecules of interest (in this case protein-DNA complexes) to discard unwanted molecules and perform the washing procedure safely.