Spontaneous Formation of Asymmetric Lipid Bilayers by Adsorption of Vesicles
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- 作者：Hanna P. Wacklin ; Robert K. Thomas
- 刊名：Langmuir
- 出版年：2007
- 出版时间：July 3, 2007
- 年：2007
- 卷：23
- 期：14
- 页码：7644 - 7651
- 全文大小：240K
- 年卷期：v.23,no.14(July 3, 2007)
- ISSN：1520-5827
文摘
We have investigated the adsorption of phospholipid mixtures using neutron reflection. Small sonicated unilamellarvesicles (SUV) composed of DOPC and d62-DPPC were incubated at 50 
C in contact with a silica surface using amethod commonly employed to form supported model membranes. The composition of the mixed supported bilayerwas found to be substantially different from that of the bulk vesicles in a direction indicating a higher affinity of DPPCfor the silica surface. Formation of an asymmetric bilayer arrangement was also discovered in all the cases studied.DPPC tended to dominate the composition of the leaflet next to silica, while the outer leaflet was generally closerto the bulk composition. The supported bilayers also exhibited increasing interfacial roughness in the outer membraneleaflet in the region of the DOPC-DPPC gel-liquid immiscibility region. To our knowledge, this is the first timethat both the structure and the absolute composition of a mixed-lipid supported bilayer have been resolved, and theresults raise a number of questions regarding the adsorption of vesicles and the properties of supported bilayers, whichare discussed in terms of the bulk phase diagram of DOPC and DPPC.
C in contact with a silica surface using amethod commonly employed to form supported model membranes. The composition of the mixed supported bilayerwas found to be substantially different from that of the bulk vesicles in a direction indicating a higher affinity of DPPCfor the silica surface. Formation of an asymmetric bilayer arrangement was also discovered in all the cases studied.DPPC tended to dominate the composition of the leaflet next to silica, while the outer leaflet was generally closerto the bulk composition. The supported bilayers also exhibited increasing interfacial roughness in the outer membraneleaflet in the region of the DOPC-DPPC gel-liquid immiscibility region. To our knowledge, this is the first timethat both the structure and the absolute composition of a mixed-lipid supported bilayer have been resolved, and theresults raise a number of questions regarding the adsorption of vesicles and the properties of supported bilayers, whichare discussed in terms of the bulk phase diagram of DOPC and DPPC.