Biophysical Journal 61: 902-910 (1992)
© 1992 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Woodle, M C Articles by Martin, F J Search for Related Content PubMed PubMed Citation Articles by Woodle, M C Articles by Martin, F J

Sterically stabilized liposomes. Reduction in electrophoretic mobility but not electrostatic surface potential.

Liposome Technology, Inc., Menlo Park, California 94025.

ABSTRACT

The electrophoretic mobility of liposomes containing a negatively charged derivative of phosphatidylethanolamine with a large headgroup composed of the hydrophilic polymer polyethylene glycol (PEG-PE) was determined by Doppler electrophoretic light scattering. The results show that this method is improved by the use of measurements at multiple angles to eliminate artifacts and that very small mobilities can be measured. The electrophoretic mobility of liposomes with 5 to 10 mol% PEG-PE is approximately -0.5 mu ms-1/Vcm-1 regardless of PEG-PE content compared with approximately -2 mu ms-1/Vcm-1 for similar liposomes but containing 7.5% phosphatidylglycerol (PG) instead of PEG-PE. Measurements of surface potential by distribution of an anionic fluorescent probe show that the PEG-PE imparts a negative charge identical to that by PG, consistent with the expectation of similar locations of the ionized phosphate responsible for the charge. The reduced mobility imparted by the surface bound PEG is attributed to a mechanism similar to that described for colloidal steric stabilization: hydrodynamic drag moves the hydrodynamic plane of shear, or the hydrodynamic radius, away from the charge-bearing plane, that of the phosphate moities. An extended length of approximately 50 A for the 2,000 molecular weight PEG is estimated from the reduction in electrophoretic mobility.

This article has been cited by other articles:

				O. Meyer, D. Kirpotin, K. Hong, B. Sternberg, J. W. Park, M. C. Woodle, and D. Papahadjopoulos Cationic Liposomes Coated with Polyethylene Glycol As Carriers for Oligonucleotides J. Biol. Chem., June 19, 1998; 273(25): 15621 - 15627. [Abstract] [Full Text] [PDF]