The lower limit to the size of small sonicated phospholipid vesicles.

The effective hydrodynamic radius of small sonicated phospholipid vesicles has been measured by photon correlation laser light scattering. It is found that the minimum radius obtained for these vesicles is within the range 10.25 +/- 0.55 nm independent of the phospholipid hydrocarbon chain length for synthetic phosphatidylcholines in the even numbered series of 12 to 18 carbons per hydrocarbon chain. The minimum radius of vesicles of egg yolk phosphatidylcholine is 10.7 +/- 0.3 nm.