Effects of pH gradients on liposomal charge states examined by capillary electrophoresis

Allison N. Phayre, Hebe M Vanegas Farfano, Mark Hayes

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Liposomes have been used for biomimetic containers and to study phenomena ranging from photo-synthetic systems to membrane fusion and dynamics. An important aspect of many preparations and in biological processes is the presence of a pH gradient across the membrane. Here, experiments were conducted using capillary electrophoresis to investigate the effects of this gradient on liposomes composed of phosphatidic acid, phosphatidylcholine, and cholesterol. pH gradients for the liposomes were created by titration of the exterior buffer; then the electrophoretic properties were analyzed by capillary electrophoresis and the size was measured by laser light scattering. Our results show that the presence of a pH gradient has a significant effect on the electrophoretic migration of liposome samples, induced principally by a change in effective charge. The differences in charge for the liposome samples are evaluated with regard to acid-base equilibria, which is shown to be inadequate to describe the dynamics of the system. A more complex capacitive theory incorporating elements of the Overbeek-Booth theory and the relaxation effect appears to more effectively describe the results and could aid in predicting liposome behavior under various pH gradient conditions.

Original languageEnglish (US)
Pages (from-to)6499-6503
Number of pages5
JournalLangmuir
Volume18
Issue number17
DOIs
StatePublished - Aug 20 2002

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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