Magnetic beads are branching out. Credit: DYNAL BIOTECH

Magnetic beads have been used for protein separation since the 1980s, but the technology is now being adapted for new proteomic applications and use with automated platforms. The market leader in paramagnetic beads is Dynal Biotech based in Oslo, Norway, and recently acquired by life-sciences giant Invitrogen in Carlsbad, California.

Dynal has just signed a co-marketing agreement for its Dynabead kits and Tecan's Freedom EVO automated platform, and has developed protocols for other platforms such as Beckman Coulter's Biomek FX and the KingFisher magnetic separation platform from Thermo Electron of Waltham, Massachusetts. “The main purpose of having magnetic beads is that you can automate the whole process,” says Lars Korsnes, director of research and development at Dynal. “The bead technology has some advantages compared with standard chromatography systems — while it's not so easy to put a whole-blood sample into a chromatography column, with magnetic beads you can put the whole sample in.”

Dynabeads, like those from some other suppliers, are superparamagnetic, with no residual magnetism outside an applied magnetic field. They are also uniform in size, shape and surface properties. This all helps to prevent the beads clogging up an automated device, Korsnes notes.

Bead technology is also more scaleable than chromatography columns, although Dynal is concentrating on more analytical or small-scale protein isolation and protein fractionation for different applications in proteomics. The firm is currently launching a new range of beads with functionalities such as ion-exchange groups, reverse-phase chromatography and hydrophobic chemistries. New owner Invitrogen plans to apply Dynal's surface technologies to a wider range of products.

The beads are also showing promise in the challenging separation of membrane proteins. “There have been some publications where one can bind membrane proteins either before or after lysing the cells,” Korsnes says. “Whether we will develop a special protocol is a question for the future, but the technology is there already.”

Tim Chapman