Membranes, amphiphilic pattern

Figure 1. Amphiphilic pattern development in nucleic acids, proteins, and membranes...

The lipid molecule is the main constituent of biological cell membranes. In aqueous solutions amphiphilic lipid molecules form self-assembled structures such as bilayer vesicles, inverse hexagonal and multi-lamellar patterns, and so on. Among these lipid assemblies, construction of the lipid bilayer on a solid substrate has long attracted much attention due to the many possibilities it presents for scientific and practical applications [4]. Use of an artificial lipid bilayer often gives insight into important aspects ofbiological cell membranes [5-7]. The wealth of functionality of this artificial structure is the result of its own chemical and physical properties, for example, two-dimensional fluidity, bio-compatibility, elasticity, and rich chemical composition. 

Also, it is not the overall lipophilicity of a drug molecule determined in octanol-buffer that is important, but the 3-D distribution pattern of lipophilicity on the surface of the molecule, which may generate a hydrophobic-hydrophilic dipole. Such a dipole can determine the specific interaction and orientation of an amphiphilic drug in a highly structured biological membrane. This includes domain formation and accumulation, change in drug conformation, and so forth. All this is... 

Thus, the hydrophilic head group and hydrophobic tail of lipids ensure assembly into the oriented bilayer array of cell membranes. The amphiphilic sheet, bilayer, and vesicle are now familiar mofits in biomimetic materials and structures. Synthetic liposomes are employed as biocompatible, biodegradable drug-delivery vehicles. Amphiphile assemblies may serve as templates mono-disperse nanoparticles are synthesized inside reverse micelles, and inorganic structures and materials such as ceramic tubules or mesoporous silica are formed around tubular micelles, rather as inorganics are patterned by vesicles in the formation of the exoskeletons of radiolarians and diatoms. 

The best multiple emulsions are likely to be prepared by the separation membrane technique, with polymeric amphiphilic, viscosity-enhancing agents, emulsified microemulsions, and proper selection of the amphiphilic blends of biomacromolecules (proteins and hydrocolloids) in each of the interfaces. The main goal remains to obtain submicron multiple emulsion droplets with longterm stability, possibly by replacing the inner emulsion with a microemulsion that is thermodynamically stable (emulsified microemulsions). Better control of the release pattern from the inner phase is stiU far from being achieved. 

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