磁性非对称双链长表面活性剂囊泡凝胶

摘要

合成了一系列含磁性反离子的非对称双疏水链长的阳离子表面活性剂,其中三氯一溴铁合十六烷基戊基二甲基铵(C16CsDMA+[FeCI3Br]-)与偶氮羧酸钠盐(AzoNa4)在酸性条件水溶液中形成磁性囊泡凝胶.运用cryo-透射电镜(TEM)、冷冻蚀刻TEM (FF-TEM)、流变仪、傅里叶变换红外光谱(FT-IR)和超导量子干涉(SQUID)等表征技术对囊泡凝胶进行了结构和性质研究,结果发现:凝胶含有曲率多变的融合性的双层囊泡,这些双分子层结构模构了自然界中各种物象的结构轮廓,展现了不可预测的多变曲率和良好柔性.聚集体双分子层膜内由长短不对称烷基链采取交错相扣的双分子层排列模式,这种构建模式结构稳定,短烷基链可游离出囊泡双分子层并伸向外部水相介质.两个相邻囊泡间的短链在疏水相互作用下形成非共价的囊泡“补丁”,疏水的囊泡“补丁”克服相邻囊泡之间的斥力而融合.磁性反离子[FeCl3Br]-不仅赋予囊泡磁性,且在囊泡的形成过程中调控烷基链的组装.这种多形态融合性囊泡为揭示膜曲率的调节机制和构建人工细胞提供实验数据和理论参考.%This report details the synthesis of a series of special magnetic cationic surfactants that contained two asymmetric alkyl chains,cetylpentyldimethylammonium trichloromonobromoferrate (C16C5DMA+ [FeCI3Br]-).The fabrication of magnetic,adhesive,poly-morphological bilayer vesicle gels with unpredictable curvature and high flexibility was investigated in detail.These colloidal bilayer nano-transformers self-adhered to form a string;they also exhibited transformable morphologies that were investigated using cryo-transmission electron microspcopy (TEM),freezing-fracture transmission electron microscopy (FF-TEM),rheological analysis,Fourier transform infrared spectrometry (FT-IR),and supemonducting quantum interference device (SQUID) techniques.Significantly,the deformed vesicles cohered to the gibbous bilayer protrusions,which closely resembled the pseudopodia of Proteus.These bilayer nano-transformers were capable of imitating structures and outlines of the natural world that,through human imagination,ranged from the island of Sicily in Italy to the larva of the Clanis bilineata and the common peanut.Most of the bilayer nano-transformers were endowed with unpredictable multi-curvature and high flexibility.A mechanism for the interlocking of the long and short alkyl chains in a bilayer arrangement was proposed in this study.The short chains departed from the bilayer to protrude externally;then,they associated non-covalently into inter-vesicular patches because of their hydrophobic interactions.Consequently,the hydrophobic inter-vesicular patches could supersede the repulsion between the vesicle membranes and allowed the vesicles to cohere.Of equal importance was that the anions [FeCl3Br]-could not only impart magnetism to the transformable vesicles,but could also tune the organization through the arrangements of the alkyl chains during the assembly process.Thus,the poly-morphology,adhesiveness,and curvature protrusions of this astounding colloidal "proteus" are eminently exploitable.This not only revealed the rudimentary regulatory mechanism of the membrane curvature,but also provided clues for the advancement of artificial cell fabrication.