Amphiphiles designed

Sophisticated amphiphile designs allow us to develop bilayer-based organic-inorganic hybrids. In the example shown in Fig. 4.29, amphiphiles with alkoxysi-lane heads are used as bilayer-forming components. At the surface of the vesicle formed, cross-linked silanol groups form an inorganic silica-like structure. 

Weissbuch, I., Berfeld, M., Bouwman, W., Kjaer, K., Als-Nielsen, J., Lahav, M., Leiserowitz, L. Separation of enantiomers and racemate formation in two-dimensional crystals at the water surface from racemic - amino acid amphiphiles design and structure, J. Amer. Chem. Soc. 119 (1997) 933-942. 

Discher BM, Koder RL, Moser CC, and Dutton PL. Hydrophilic to amphiphilic design in redox protein maquettes. Curr. Op. Chem. Biol. 2003 7 741-748. 

Fig. 8. De novo designed a-hehcal proteins. Dimers of the amphiphilic helix-forming peptide a B, GELEELLKKLKELLKG (see Table 1), in which the nature of the linker connecting the individual heflces plays a critical role in the stmcture of the final protein, (a) Using a Pro residue as the linker, ie, a B-Pro-a B, three molecules aggregated to form a trimeric coded-cod. (b) Using Pro-Arg-Arg as the linker, ie, a B-Pro-Aig-Arg-a, resulted in the...

Lattice models for bulk mixtures have mostly been designed to describe features which are characteristic of systems with low amphiphile content. In particular, models for ternary oil/water/amphiphile systems are challenged to reproduce the reduction of the interfacial tension between water and oil in the presence of amphiphiles, and the existence of a structured disordered phase (a microemulsion) which coexists with an oil-rich and a water-rich phase. We recall that a structured phase is one in which correlation functions show oscillating behavior. Ordered lamellar phases have also been studied, but they are much more influenced by lattice artefacts here than in the case of the chain models. 

This review article attempts to summarize and discuss recent developments in the studies of photoinduced electron transfer in functionalized polyelectrolyte systems. The rates of photoinduced forward and thermal back electron transfers are dramatically changed when photoactive chromophores are incorporated into polyelectrolytes by covalent bonding. The origins of such changes are discussed in terms of the interfacial electrostatic potential on the molecular surface of the polyelectrolyte as well as the microphase structure formed by amphiphilic polyelectrolytes. The promise of tailored amphiphilic polyelectrolytes for designing efficient photoinduced charge separation systems is afso discussed. 

Bates F.S. and Fredrickson G.H., Block copolymers-designer soft materials, Phys. Today, 52, 32, 1999. Alexandridis P. and Lindman B. (eds.). Amphiphilic Block Copolymers Self-Assembly and Applications, Elsevier, Amsterdam, 2000. 

Both the 3i4- and 2.5i2-helical backbones have been found suitable for the design of antimicrobial /9-peptides. In order to cluster polar residues on one face of the helix, amphiphilic 3i4-helical /9-peptides have been constructed from hydro-phobic-cationic-hydrophobic or hydrophobic-hydrophobic-cationic residue triads... 

The shape-persistent, structurally well-defined nature of PAMs and PDMs make them attractive models for binding guest molecules within their cavities. In 1995, Hoger and Enkelmann reported the construction of the first meta/para-PAM/PDM hybrid designed to possess hydrophobic and hydrophilic substituents for subsequent use in host guest chemistry [71]. Macrocyclic amphiphile 116 was assembled via the straightforward manner depicted in Scheme 26. 

Polymers and copolymers are among the most beneficial materials produced by synthetic chemistry. The invention and commercialization of new polymeric materials with radical new properties provides an opportunity to monopolize the market and justify the expense involved in the research and development. The commercialization of new polymers or copolymers always presents scale-up and design challenges. Scientists have recently developed new polymeric materials whose commercial impact has yet to be realized. Examples are semiconductive and conductive polymers and amphiphilic dendritic block copolymers. Other promising materials, such as polymers for (targeted) drug delivery and... 

Synthesis. The procedures used for the preparation of other amphiphilic networks (1) could not be used for the synthesis of PHEMA-1-PIB because of the insolubility of PHEMA in solvents that dissolve PIB e.g., THF. The above described silylation-desilylation procedure was designed to provide mutual solubility of the phases and thus to make the synthesis possible. 

The vesicles made from lipid bilayers are analogous to polymersomes, which are vesicles formed from high molecular weight amphiphilic block copolymers [94—96], Unlike the micelles discussed earlier from the similar copolymer components, the presence of bilayer walls formed from the aggregation of hydrophobic domains provides new properties. They can be designed to respond, for example, by opening or by disassembly, to external stimuli such as pH, heat, light, and redox processes [97]. This makes them usable as scaffolds for cascade reactions, even those with combinations of enzymes [98, 99]. 

John, G. and Vemula, P.K. (2006) Design and development of soft nanomaterials from biobased amphiphiles. Soft Matter, 2, 909-914. 

An interesting twist to the story is provided by studies on N. brasiliensis, which secretes three distinct isoforms of AChE, designated A, B and C (Ogilvie et al, 1973). These enzymes can be easily separated by nondenaturing electrophoresis due to their distinct pis, and this is illustrated in Fig. 11.1, which also shows the distinct electrophoretic properties of the amphiphilic enzyme (arrowed) found only in somatic extracts and therefore presumably associated with neuromuscular function. The overall amount of AChE produced by this parasite increases dramatically following establishment in the jejunum, and a switch in isoform expression occurs,... 

The molecular descriptors refer to the molecular size and shape, to the size and shape of hydrophilic and hydrophobic regions, and to the balance between them. Hydrogen bonding, amphiphilic moments, critical packing parameters are other useful descriptors. The VolSurf descriptors have been presented and explained in detail elsewhere [8]. The VolSurf descriptors encode physico-chemical properties and, therefore, allow both for a design in the physico-chemical property space in order to rationally modulate pharmacokinetic properties, and for establishing quantitative structure-property relationships (QSPR). 

Kim, J.M., Sakamoto, Y., Hwang, Y.K., Kwon, Y.U., Terasaki, O., Park, S.E. and Stucky, G.D. (2002) Structural design of mesoporous silica by micelle-packing control using blends of amphiphilic block copolymers. Journal of Physical Chemistry B, 106, 2552— 2558. 

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