Lipids, self-assembly into complex structures

The stractural and functional complexity of biomembranes has ehal-lenged researehers to develop simpler artificial models to mimie their properties. Amphiphilic block copolymers are of particular interest, beeause of the dual environmental affinity that is associated with covalently bound hydrophobie and hydrophilic blocks. These strive to minimize their eontaet, and therefore drive self-assembly into assemblies with different arehi-teetures. Based on their chemical specificity, as for example the hydrophilie-to hydrophobie ratio, amphiphilic block copolymers can self-assemble in dilute aqueous solutions into micelles, vesicles, tubes, wire-like structures, nanopartieles, or planar membranes at water-air interfaces. Synthetic membranes have greater mechanical stability than phospholipids because of the higher moleeular weight (Mw) of amphiphilic block copolymers, and thus are thicker and stiffer than lipid bilayers. 

In Chapter 3, we introduced the concept of the surfactant and discussed how molecules with hydrophobic and hydrophilic sections will self-assemble into lyotropic phases in aqueous solution. The stability of a specific phase depends on molecular shape and concentration in the solvent. In the discussions that follow, we focus on the phase behavior of a simplified model membrane containing only lipids, even though the real cell membrane consists of a complex mbcture of many different varieties of lipids, sterols, and membrane proteins. Figure 6.3 shows molecular structures for some common lipid molecules found in the cell membrane. For a detailed description of the cell membrane, I recommend The Structure of Biological Membranes as further reading. ... 

Another use of the DNA-lipid complex was reported by Wong and coworkers [33]. The DNA molecule structural features can be imprinted into CdS nanostructures by using self-assembled DNA-membrane templates. The initial application of the DNA-lipid multilamellar structure was the use as gene carriers in gene therapy, and many reports [34-39] were published (Fig. 6b). To prepare the DNA templates, anionic DNA was reacted with a mixture of... 

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