I prepare cationic liposomes using stearyl amine through the lipid film method. However, when I use higher proportions of stearyl amine, precipitation occurs after hydration. Could this be related to the pH of the PBS buffer? I selected a pH of 7.4.
Hello Masoud, the precipitation could be related to the pH and to the PBS buffer as well. Stearyl amine is a primer amine, I do not know the pK value of the amine group in this molecule, but the pH of your buffer should be below the pK. So decreasing the pH might help, though I think at the current pH of 7.4 this amine is charged. On the other hand, this charged amine might form a strong ionic bond to the phosphate group of PBS, so I recommend using a HEPES or TRIS buffer instead. Hope this helps. Best, Karoly
Dear Masoud Ojarudi The first thing that cross my mind is the fact that stearylamine has a fairly high melting point (above 50 oC). You could try to mixed the mixture at a temperature of let's say 60 oC.
Best regards.
PS. The pKa of primary amines are around pH 10 so pH 7.4 should be okay.
Dear Professor Karoly Liliom and Professor Rob Keller,
I would like to express my sincere gratitude for your thoughtful responses. Your insights are greatly appreciated, and I am thankful for the time and effort you have dedicated to addressing my inquiries
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