I do have some liposomes in a buffer with 50 or 100 mM CaCl2
I would like to test them with a 1-2 mM CaCl2 final concentration in the buffer but my lipid concentration is not high enough to get a homogeneization by successive dilutions... so I am thinking about changing the buffer in which they are suspended.
Is there a way to do this?
Ideas that come to me for now:
- Spinning at low rpm and decant the supernatant and resuspend in a new buffer with the desired concentration. This could work but I'm afraid my membrane are not enough rigid to handle that...
- Perform a sephadex column with a new buffer but I'm afraid the retention is not long enough to get them suspended in the new buffer without any contamination with the former one...
Thanks for your help!
I usually use small desalting columns (PD-10 from GE), and it works fine. Equilibrate the column with your new buffer, apply your liposome suspension and collect the eluate. Just make sure you never apply more sample than the recommendations. I changed from 100 mM NaCl to 100 mM KCl and had less than 1 mM NaCl left in my eluted sample.
Spinning down works in principle, but is efficient only at very high speeds (>20 000 rpm) and some liposomes do break. I don't recommend unless you have really tough liposomes.
Good luck!
In addition to desalting columns, as recommended by Kamil Adam Górecki, you could also use dialysis. It takes longer (overnight), but is easy, usually gives high yield, and scales up more easily. You would dialyze the liposomes against a large volume of a solution containing the desired final CaCl2 concentration, while using magnetic stirring to keep the sample well-mixed.
Thanks, I will go for the desalting column which might be quite faster for the small amount of liposome I have for now.
Thanks for your answers !
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