Morphological and Nanomechanical Behavior of Supported Lipid Bilayers on Addition of Cationic Surfactants
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- 作者：Lia M. C. Lima ; Marina I. Giannotti ; Lorena Redondo-Morata ; M. Lu铆sa C. Vale ; Eduardo F. Marques ; Fausto Sanz
- 刊名：Langmuir
- 出版年：2013
- 出版时间：July 30, 2013
- 年：2013
- 卷：29
- 期：30
- 页码：9352-9361
- 全文大小：595K
- 年卷期：v.29,no.30(July 30, 2013)
- ISSN：1520-5827
文摘
The addition of surfactants to lipid bilayers is important for the modulation of lipid bilayer properties (e.g., in protein reconstitution and development of nonviral gene delivery vehicles) and to provide insight on the properties of natural biomembranes. In this work, the thermal behavior, organization, and nanomechanical stability of model cationic lipid鈥搒urfactant bilayers have been investigated. Two different cationic surfactants, hexadecyltrimethylammonium bromide (CTAB) and a novel derivative of the amino acid serine (Ser16TFAc), have been added (up to 50 mol %) to both liposomes and supported lipid bilayers (SLBs) composed by the zwitterionic phospholipid DPPC. The thermal phase behavior of mixed liposomes has been probed by differential scanning calorimetry (DSC), and the morphology and nanomechanical properties of mixed SLBs by atomic force microscopy-based force spectroscopy (AFM-FS). Although DSC thermograms show different results for the two mixed liposomes, when both are deposited on mica substrates similar trends on the morphology and the mechanical response of the lipid鈥搒urfactant bilayers are observed. DSC thermograms indicate microdomain formation in both systems, but while CTAB decreases the degree of organization on the liposome bilayer, Ser16TFAc ultimately induces the opposite effect. Regarding the AFM-FS studies, they show that microphase segregation occurs for these systems and that the effect is dependent on the surfactant content. In both SLB systems, different microdomains characterized by their height and breakthrough force Fb are formed. The molecular organization and composition is critically discussed in the light of our experimental results and literature data on similar lipid鈥搒urfactant systems.