Cambio - Excellence in Molecular Biology

Why are LabOnABeads at the cutting edge of antibody purification and pull-down technology?

Friday, 17 February 2017

Here is the answer that we got from an expert in the LOAB team in Uppsala:

The LOABeads system is based on agarose beads, which contain a large internal surface for interaction between an immobilized ligand and its target molecule; e.g., protein A and and IgG antibody. Synthetic beads, including many magnetic beads from alternative suppliers, are solid and all interactions takes place on the outer surface of the beads.

LOAB agarose beads have been magnetized with a specific proprietary method. This, in combination with the large size of the agarose particle (average diameter 90 µm), enables a high degree of magnetization per bead. In contrast, synthetic beads available from other companies are small, for example 1-4.5 µm, have a core of magnetized material and due to the small size, a relatively small magnetization is obtained per bead. Using small synthetic beads in a microtube works fine. We haven’t measured the time for separation of these beads in a microtube, but LOABeads magnetic agarose separate in 1-2 seconds. For large vessels, synthetic beads will not separate efficiently towards a passive magnet. They are too weakly magnetized. LOABeads particles, though, separate fine in a 500 ml bottle in a semi-passive manner (the liquid needs to swirl in the bottle for the beads to separate to the side of the inner wall of the vessel). The bulk separate within one minute, while the remaining beads take an additional 2-4 minutes. 

The chemistry for covalently coupling ligands to LAOB activated magnetic agarose beads, is also employs unique proprietary technology. This chemistry enables a high degree of coupling of ligands, which is especially apparent for LOAB Protein A with a maximum binding capacity at 60 mg IgG/ml beads.

LOAB magnetic separators use the strong magnetic force from neodymium magnets. LOAB MagSep 500 contain six magnetic elements, enabling a capacity to separate and hold at least 30 ml of our magnetic agarose beads. This would be completely impossible using standard synthetic magnetic beads.

So, the LOABeads system works at the microscale, as do synthetic magnetic beads. LOABeads do, however, have a much larger binding capacity and, for reasons mentioned above, also work well at large scale, where othe MagSep 500-separator can handle 500 ml bottles. In addition to being able to perform parallel purification at microscale, LOAB parallel purification is also possible with 500 ml samples. Doing five bottles side by side is not a problem, giving a total sample volume of 2.5 liters.

When purifications involve large volumes, e.g. 20 ml to 2 liters, or so, and LOAB high capacity protein A beads are used, the method can be a direct substitute for column chromatography and associated instrumentation, freeing up time on your busy chromatography instruments and rapidly delivering purified antibody or antibodies. The ability to perform parallel purification from many samples, can easy save days or even weeks.

With the LOABeads system there is minimal set-up time, no instrument maintenance, you don’t have to worry about your instrument breaking down, and there’s no need to wait a week for spare-parts to arrive! If you have LOABeads and a magnet separator, you are always ready to purify.

Article Source: Cambio / LOAB