Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA.
Langmuir. 2011 Sep 6;27(17):10840-6. doi: 10.1021/la201438s. Epub 2011 Aug 4.
The interaction of surface-active molecules with lipid bilayers is ubiquitous both in biological systems and also in several technological applications. Here we explore the interaction of ionic surfactants with liposomes whose composition mimics the ocular epithelia. In this study, liposomes with a composition mimicking ocular epithelia are loaded with calcein dye above the self-quenching concentration. The liposomes are then exposed to surfactants, and the rate of dye leaked from the liposomes due to the interaction of surfactants is measured. Both cationic and anionic surfactants at various concentrations and ionic strengths are explored. Results show that the liposome bilayer permeability to the dye increases on exposure to the surfactants, leading to the release of the dye trapped in the core. However, the dye release stops after a finite time, suggesting a transient increase in permeability followed by healing. The leakage profiles exhibit two different timescales for the cationic surfactant but only one timescale for the anionic surfactant. The total dye leakage increases with surfactant concentration, and at a given concentration, the dye leakage is significantly higher for the cationic surfactants. The timescale for the healing decreases with increasing surfactant concentration, and increasing ionic strength increases the dye leakage for the anionic surfactant. These results show that the surfactant binding to the lipid bilayer increases the permeability while the bilayers heal likely because of the surfactant jump from the outer to the inner leaflet and/or rearrangement into tighter aggregates.
表面活性分子与脂质双层的相互作用在生物系统和几种技术应用中都普遍存在。在这里，我们探索了模拟眼部上皮细胞组成的脂质体与离子型表面活性剂的相互作用。在这项研究中，模拟眼部上皮细胞组成的脂质体被加载了超过自猝灭浓度的钙黄绿素染料。然后将脂质体暴露于表面活性剂中，并测量由于表面活性剂的相互作用而从脂质体中泄漏的染料的速率。研究了各种浓度和离子强度的阳离子和阴离子表面活性剂。结果表明，脂质体双层对染料的通透性在暴露于表面活性剂后增加，导致被困在核心中的染料释放。然而，染料释放在有限的时间后停止，表明通透性短暂增加后再愈合。阳离子表面活性剂的泄漏曲线表现出两个不同的时间尺度，但阴离子表面活性剂只有一个时间尺度。总染料泄漏随表面活性剂浓度的增加而增加，并且在给定浓度下，阳离子表面活性剂的染料泄漏显著更高。愈合的时间尺度随表面活性剂浓度的增加而减小，而增加离子强度会增加阴离子表面活性剂的染料泄漏。这些结果表明，表面活性剂与脂质双层的结合增加了通透性，而双层的愈合可能是由于表面活性剂从外层跳到内层，和/或重新排列成更紧密的聚集体。
