Biomagnetic Separation - Magnetic Bead Assays | 147
Optimize Magnetic Bead Protocols
Here are some suggestions to consider for optimizing your magnetic bead assays:
l Plate Type: Flat-bottom plates are recommended for magnetic bead assays because
more of their well surface sits closer to the magnet, resulting in increased magnet
strength, than with other plate formats. If you must use round-bottom plates, increase
the between-cycle soak time to improve bead separation during processing.
l Magnet Adapter Height Offset: Deploy this offset to increase the Z-axis or height
setting in all processing options to accommodate the increased height of the magnet.
See Determine Magnet Height Offset. Use of this feature may eliminate the need to
"Adjust the Aspirate height" described below.
l Shake/Soak Step: Begin the protocol with a delay to let the magnetic beads settle.
Also, specify a mid-cycle soak to let the beads settle after fluid is dispensed to the plate,
e.g. include a 60 second soak before and between cycles.
l 6CW Aspirate Travel Rate: select 6CW for the aspirate travel rate. The CW travel
rates are designed to minimize disruption to cell layers on the bottom of the well. The
same principle applies to magnetic bead assays.
l Adjust the Aspirate height: increase the aspirate height setting (Z-axis) which will
increase the residual fluid in the wells but also preserve the beads. Good results were
obtained when keeping the aspirate height around 15.0 mm above the plate carrier for
all but a last Final Aspirate (disabled between cycles).
l Adjust the Aspirate position: When using Flat Magnets below, position the aspirate
tubes near the sides of the wells (X-axis), if possible, to improve bead retention.
l As always, before running assays, we recommend testing new protocols using deionized
or distilled water and a little Tween
®
20 with the desired microplate and a magnet
installed.
Flat Magnets
Use this information about the flat magnets to fine-tune wash protocol settings:
96F Magnet 7103016
384F Magnet 7103017
The 96- and 384-well magnets are structured differently. Their force fields traverse
the magnet in opposite directions. Magnetic beads in the wells will be drawn to the
center. For the best bead retention, reposition the aspirate tubes in the proper axis:
BioTek Instruments, Inc.
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