Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, United Kingdom.
Langmuir. 2010 Jan 5;26(1):320-7. doi: 10.1021/la9034936.
We have investigated the formation of supported surfactin-phospholipid mixed bilayers using neutron reflectometry. Micellar mixtures of phospholipid (diphosphatidyl choline, DPPC), surfactin, and beta-d-dodecyl maltoside were used to make the deposition. When the surfactin concentration is at its critical micelle concentration (CMC = 6 x 10(-6) M) in the bulk solution, there is no adsorption at all on the silica. When the surfactin concentration is lowered below the CMC, a mixed bilayer of surfactin and DPPC is formed. Since surfactin does not adsorb on silica from solutions of surfactin alone, this shows that there is a strong attraction between surfactin and DPPC. The variation of adsorbed amount, composition, and structure of the adsorbed layer are consistent with the attractive interaction between surfactin and DPPC and with their respective negative and positive affinities for the silica surface. Three phospholipid isotopic contrasts were measured and used to define the composition and structure of the surfactin-phospholipid bilayer. The maximum amount of surfactin in the bilayer reaches a mole fraction of about 0.2 and this is located in the outer leaflet of the bilayer within the headgroup and part of the adjacent chain region.
我们使用中子反射技术研究了表面活性剂 - 磷脂混合双层的形成。使用混合胶束的磷脂（二棕榈酰磷脂酰胆碱，DPPC）、表面活性剂和β-D-十二烷基麦芽糖苷来进行沉积。当表面活性剂在本体溶液中的浓度达到其临界胶束浓度（CMC = 6×10（-6）M）时，在二氧化硅上根本没有吸附。当表面活性剂浓度降低到低于 CMC 时，会形成表面活性剂和 DPPC 的混合双层。由于单独的表面活性剂溶液中表面活性剂不会在二氧化硅上吸附，这表明表面活性剂和 DPPC 之间存在很强的吸引力。吸附量、组成和吸附层结构的变化与表面活性剂和 DPPC 之间的吸引力以及它们对二氧化硅表面的各自负和正亲和力一致。测量了三种磷脂同位素对比，并用于定义表面活性剂 - 磷脂双层的组成和结构。双层中表面活性剂的最大量达到约 0.2 的摩尔分数，并且位于双层的外层的头部基团和相邻链区的一部分中。
