For buffer exchange of proteins that are very sensitive to pH and concentration changes, e.g. those that precipitate out easily, what’s the best way to handle this?
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Diafiltration! General dialysis can work well too, but it takes a long time, often overnight, and often leads to sample loss handling delicate dialysis bags. Whereas with diafiltration using ultrafilters you can perform the steps independently, but also in parallel to an ultrafiltration step. I.e. you can add a buffer reservoir to a lab based TFF system, that will draw in fresh buffer as the sample concentrates. There are even centrifugal concentrators that can house a buffer cup that allows for diafiltration whilst in the centrifuge, such as in the following link.
https://www.sartoriusglobal.com/mediafile/Appl_Vivaspin-20_Diafiltration-cups_SL-4076-e.pdf
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