Nakahara Hiromichi, Nakamura Shohei, Hiranita Takato, Kawasaki Hideya, Lee Sannamu, Sugihara Gohsuke, Shibata Osamu
Division of Biointerfacial Science, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Langmuir. 2006 Jan 31;22(3):1182-92. doi: 10.1021/la0524925.
Surface pressure (pi)-, surface potential (deltaV)-, and dipole moment (mu(perpendicular))-area (A) isotherms and morphological behavior were examined for monolayers of a newly designed 18-mer amphiphilic alpha-helical peptide (Hel 13-5), DPPC, and DPPC/egg-PC (1:1) and their combinations by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM), and atomic force microscopy (AFM). The newly designed Hel 13-5 showed rapid adsorption into the air-liquid interface to form interfacial films such as a SP-B function. Regardless of the composition and constituents in their multicomponent system of DPPC/egg-PC, the collapse pressure (pi(c); approximately 42 mN m(-1)) was constant, implying that Hel 13-5 with the fluid composition of egg-PC is squeezed out of Hel 13-5/DPPC/egg-PC monolayers accompanying a two- to three-dimensional phase transformation. FM showed that adding a small amount of Hel 13-5 to DPPC induced a dispersed pattern of ordered domains with a "moth-eaten" appearance, whereas shrinkage of ordered domains in size occurred for the DPPC/egg-PC mixture with Hel 13-5. Furthermore, AFM indicated that (i) the intermediate phase was formed in pure Hel 13-5 systems between monolayer states and excluded nanoparticles, (ii) protrusions necessarily located on DPPC monolayers, and (iii) beyond the collapse pressure of Hel 13-5, Hel 13-5 was squeezed out of the system into the aqueous subphase. Furthermore, hysteresis curves of these systems nicely resemble those of the DPPC/SP-B and DPPC/SP-C mixtures reported before.
通过威尔海姆法、电离电极法、荧光显微镜（FM）和原子力显微镜（AFM），研究了新设计的18聚体两亲性α-螺旋肽（Hel 13-5）、二棕榈酰磷脂酰胆碱（DPPC）、DPPC/蛋黄卵磷脂（1:1）及其组合的单层膜的表面压力（πi）、表面电位（ΔV）、偶极矩（μ⊥）-面积（A）等温线以及形态行为。新设计的Hel 13-5迅速吸附到气液界面形成诸如表面活性蛋白B（SP-B）功能的界面膜。无论DPPC/蛋黄卵磷脂多组分体系中的组成和成分如何，其崩溃压力（πc；约42 mN m-1）是恒定的，这意味着具有蛋黄卵磷脂流体组成的Hel 13-5在伴随二维到三维相变的过程中从Hel 13-5/DPPC/蛋黄卵磷脂单层膜中被挤出。FM显示，向DPPC中添加少量Hel 13-5会诱导出具有“虫蛀”外观的有序域分散模式，而对于含有Hel 13-5的DPPC/蛋黄卵磷脂混合物，有序域尺寸会缩小。此外，AFM表明：（i）在纯Hel 13-5体系中，单层状态和排除的纳米颗粒之间形成了中间相；（ii）突起必然位于DPPC单层膜上；（iii）超过Hel 13-5的崩溃压力后，Hel 13-5被挤出体系进入水相亚层。此外，这些体系的滞后曲线与之前报道的DPPC/SP-B和DPPC/SP-C混合物的滞后曲线非常相似。
