Loading of amphipathic weak acids into liposomes in response to transmembrane calcium acetate gradients

Biochim Biophys Acta. 1995 Dec 13;1240(2):257-65. doi: 10.1016/0005-2736(95)00214-6.


We describe a novel procedure to load amphipathic weak acid molecules into preformed liposomes. Differences in calcium acetate concentrations across the liposomal membrane induce an increase of the internal pH. This pH imbalance serves as an efficient driving force to load and accumulate weak acids (5(6)-carboxyfluorescein and nalidixic acid) inside the lipid vesicles. The mechanism of loading and the relevance of the method in drug delivery systems are discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / chemistry*
  • Acetic Acid
  • Acids / chemistry*
  • Fluoresceins
  • Hydrogen-Ion Concentration
  • Liposomes / chemistry*
  • Nalidixic Acid / chemistry


  • Acetates
  • Acids
  • Fluoresceins
  • Liposomes
  • 6-carboxyfluorescein
  • Nalidixic Acid
  • Acetic Acid