Specialized Liquid Class for Magbeads

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Does anyone have experience with and advise whether a new customized liquid class needs to be created with specialized handling for resuspending/transferring magbeads (or even removing liquid from over the top of the beads when on the plate magnet)? In this case I’m using the Fluent/Fluentcontrol, and I’m fairly experienced, but was wondering if anyone had suggestions or guidelines for things like airgaps, asp/disp speeds, acceleration factors, etc

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In my experience anytime you want to dispense magbeads you need to do so fairly slowly. Otherwise the PEG inside the tips beads up on the sides of the tip and won’t completely dispense. This isn’t a problem when aspirating, only dispensing. Generally then if I want to mix I will aspirate fairly quickly, but dispense slowly with a decently long pause (~500ms) after dispensing to allow all the PEG to exit the tips. This would also apply if you want to dispense beads into a plate.

Aspirating supernatant shouldn’t have that problem. If you want to keep the supernatant from the original binding step (a two sided bead cleanup) then you’ll also want to dispense it slowly as the supernatant will have a high percentage of PEG.

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Building on top of @jnecr suggestions, a few additional tips.

  • When mixing at trough, cycle aspirate low to dispense high or vice versa. The beads settle and Tecan tips guide liquid jets like a concentrated stream so you can see insufficient mixing if you just cycle asp/dispense down near the bottom of the trough.
  • Beads can be tricky and lead to Pressure Out Of Range issues if microscript gets too complicated, especially when aspirating or dispensing the viscous solution near the base of a well or trough.
  • For aspirating supernatant after magnetization, make sure you aspirate very slow - 30 µL/s might be a good starting point depending on volume. For these steps I like to simplify the liquid classes to very basic speeds and accelerations so I’m not troubleshooting some third order differential equation that Tecan tends to insert into their base liquid classes.
  • Airgaps. I wouldn’t fiddle around with airgaps too much, just keep them moderate and simple static volumes to assist troubleshooting and development.
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