Properties of phosphatidylcholine bilayers as revealed by mixed-acyl phospholipid fluorescent probes containing n-(9-anthroyloxy) fatty acids
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Updated: Oct 19, 2026

Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
1Department of Cellular Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000.
Abstract:
A series of five mixed-acyl phosphatidylcholine (PC) fluorescent probes having the structure 1-caproyl-2-(n-(9-anthroyloxy)-acyl)-sn-glycero-3-phosphocholine, where the sn-2 anthroyloxy-labeled acyl chain is stearic acid (n = 2,6,9,12) or palmitic acid (n = 16), have been prepared. These probes have been used to study the thermal behavior and transbilayer organization of 1,2-distearoyl-PC (C(18)C(18)PC), 1-stearoyl-2-caproyl-PC (C(18)C(10)PC), and 1-caproyl-2-stearoyl-PC (C(10)C(18)PC) multilamellar dispersons. These probes reported the noninterdigitated gel to liquid-crystalline phase transition of C(18)C(18)PC at 55.1 degrees C and the mixed-interdigitated gel to liquid-crystalline phase transitions of C(18)C(10)PC and C(10)C(18)PC at 19.1 and 10.1 degrees C, respectively. The results suggest that, upon cooling, the C(18)C(10)PC liquid-crystalline phase transforms to the mixed-interdigitated gel phase by way of a partially interdigitated gel-phase intermediate. Isothermal plots of anisotropy versus the position of the anthroyl moiety on the sn-2 acyl chain of the PC probes were used to construct transbilayer anisotropy profiles of the gel phases of the three bilayer systems. These anisotropy profiles can serve as 'interdigitation signatures' that clearly distinguish the noninterdigitated from the mixed-interdigitated gel-phase bilayer organization. In the liquid-crystalline phase, the anisotropy profiles suggest that the dynamic motions of the disordered acyl chains of the mixed-acyl PCs are influenced by the interpenetration of the chains from the opposing leaflets of the bilayer.
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