I'm preparing liposomes from SPC and Na cholate & realised that the zeta potential reduced to -10 from -35 by adding a protein solution. Is there any way to increase zeta potential? Is zeta potential >+/- 30 needed to stabilise liposomes?
Is protein adsorption a requirement for your application? For charge stabilization you probably need way lower than -30 mV. Can you do steric stabilization?
A common way is to change pH unless you are restricted to using a buffer etc.
The question of zeta potential doesn't have a simple answer. The concentration of dissolved ionic material (simple salts, polyelectrolytes) etc plays a very important role. What other materials are present in your system? If there are salts, do you know the concentrations? Do you know the pH of your two solutions before mixing?
The purity of the Phosphatidylcholine you are using could also have a big influence on your system.
Hi Omar Gonzalez-Ortega thanks for the reply. Protein adsorption is not a requirement but encapsulation. The entrapment ratio is low as well as the zeta potential. Could you please recommend some ways to do steric stabilisation? Th@@anks!
Hi John Francis Miller thanks for the comment. I'm using PBS to solubilise my protein. No other things are present. In this case, what is the best way because extreme pH may affect the stability of protein. Thanks!
Hi Florence Olechowski thanks for the comment. The purity of SPC use is high enough (95-99%). Do you have any recommendation?
Do you want to encapsulate protein molecules then? If so do you want to accomplish this during liposome preparation or afterwards. A lipid bearing a peg moiety is the simplest way to accomplish steric stabilization.
It is highly likely that adding the PBS is pushing your instrument to its limits. Commercial instruments fail to measure accurately at ionic strengths at physiological levels or higher even though the results may appear to be good. Unfortunately, this is not widely known and certainly not highlighted by the manufacturers.
I have developed a new form of electrophoretic light scattering that does measure correctly and the differences are dramatic. I gave a presentation about this at the ACS National Meeting two weeks ago and I have made it available on-line:
http://www.enlightenscientific.com/
Follow the link for NG ELS on the homepage.
(Alternatively, view it in my ResearchGate PALS project.)
After watching it, you should have a good idea as to why your measured zeta potential is probably lower than the true value. The presentation runs for about 18min.
John.
Hi Omar Gonzalez-Ortega thanks for the reply. Yes I would like to encapsulate during hydration of lipid film. Could you suggest some examples of lipid with peg moiety? Thanks!
Hi John Francis Miller thanks for the information. I'm wondering if it will be ok after dilution with PBS. Bu t I afraid there is a chance where zeta potential might change.
https://avantilipids.com/product-category/polymers-polymerizable-lipids/mpeg-phospholipids
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