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Polymer-induced leakage of cations from dioleoyl phosphatidylcholine and phosphatidylglycerol liposomes

Thomas, James L. and Tirrell, David A. (2000) Polymer-induced leakage of cations from dioleoyl phosphatidylcholine and phosphatidylglycerol liposomes. Journal of Controlled Release, 67 (2-3). pp. 203-209. ISSN 0168-3659. doi:10.1016/S0168-3659(00)00209-1.

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The amphipathic polyacid, poly(2-ethylacrylic acid) (PEAA) has recently been shown to form fluctuating channels in patch-clamp measurements of phospholipid bilayers [J.C. Chung, D.J. Gross, J.L. Thomas, D.A. Tirrell, L.R. Opsahl-Ong, Macromolecules 29 (1996) 4636–4641.]. To explore this phenomenon further, we have quantified the PEAA-mediated pH-dependent release of sodium and calcium ions from phospholipid vesicles. Permeability to calcium increases linearly with polymer concentration and exponentially with decreasing pH. Permeabilization of negatively charged phosphatidylglycerol (PG) liposomes occurs to a similar extent and with a similar pH dependence to that of zwitterionic phosphatidylcholine (PC) liposomes, implying that a charge neutral species is responsible for the leakage. The pH dependence of leakage shows that the cooperative protonation of from three to five carboxylate anions is required for permeabilization. Such neutralization could result in a neutral segment of polymer chain of sufficient length to span the bilayer.

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Tirrell, David A.0000-0003-3175-4596
Additional Information:© 2000 Elsevier Science B.V. All rights reserved. Received 24 September 1999; accepted 19 January 2000.
Issue or Number:2-3
Record Number:CaltechAUTHORS:20150114-111319852
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53375
Deposited By: Anne Hormann
Deposited On:16 Jan 2015 04:32
Last Modified:10 Nov 2021 20:01

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