Nanostructure conformation

Knowledge about protein folding and conformation in biological systems can be used to mimic the design of a desired nanostructure conformation from a particular MBB and to predict the ultimate conformation of the nanostructure [152]. Such biomimetic nano-assembly is generally performed step by step. This wiU allow observation of the effect of each new MBB on the nanostructure. As a result, it is possible to control accurate formation of the desired nanostmcture. Biomimetic controlled and directed assembly can be utilized to investigate molecular interactions, molecular modeling, and study of relationships between the composition of MBBs and the final conformation of the nanostmctures. Immobilization of molecules on a surface could facilitate such studies [153]. 

The knowledge about protein folding and conformation in biological systems can be used to mimic the design of a desired nanostructure conformation from a particular MBB and to predict the ultimate conformation of the nanostructure. 

A unique feature of such DNA-directed self-assemblies is their site-selective immobilization, which makes it possible to construct well-defined nanostructures. On the other hand, the possibility of the introduction of a vast number of substitutes (like peptidic sequences, nucleoproteins, of hydrophobic hydrocarbon chains) to an adamantane core (adamantyl) makes such a process capable of designing steric colloidal and supramolecular conformations by setting hydrophobic/hydrophilic and other interactions. In addition, the rigidity of the adamantane structure can provide strength and rigidity to such self-assemblies [150]. 

Although solution-based approaches can be used as a direct replacement for vacuum-based processes, one of the key aspects of atmospheric solution-based processing is that, by virtue of it being non vacuum and using conformal solution-based precursors, it can lead to a next generation of hybrid and nanostructured materials and devices by enabling unique composites... 

Sheets also play an important role in the construction of peptide-based functional nanohbrous materials. /3-sheets are preferred over a-helices as molecular building blocks in the fabrication of artificial nanostructured materials perhaps because of the growing interest in understanding the self-assembly of two types of namral /3-sheet products silk protein and amyloid-Uke /3-sheets. Furthermore, extended /3-sheet conformation is relatively easy to achieve. Indeed, preventing their formation, particularly in high concentration or at high temperature, can be difficult in both synthetic and natural constructs. 

Dong H, Paramonov SE, Aulisa L, Bakota EL, Hartgerink JD. Self-assembly of multi-domain peptides balancing molecular frustration controls conformation and nanostructure. J Am Chem Soc 2007 129 12468-12472. 

Another interesting approach to solve the problem of preparing peptide nanostructures with predictable solution conformations has been taken by Gellman and Dado [8]. They designed an 18-residue peptide 6 that could have... 

To design photo-induced electron transfer devices, the group of Nishino [69] reported the preparation of a bis-a-helical nanostructure, 74. The peptidic framework was designed to orient rigidly in space the redox triad, composed of a Ru2 + complex, an anthraquinone, and two propylviologens, when incorporated in a lipid bilayer (Fig. 28). Although the compound exhibited a strong a-helical content in methanol, its conformation in a vesicle bilayer was different and undetermi ned. Nevertheless, irradiation of the Ru(II) complex of 74 resulted in a slow electron transfer. 

Polysilane-based nanostructured composites were synthesized by the inclusion of poly(di-w-hexylsilane) (Mw = 53,600) into mesoporous, Si-OH-rich silica with a pore size of 2.8 nm.81 Two PL bands are observed for the composite. A narrow band at 371 nm, assigned to a PDHS film on a quartz substrate is blue shifted by 20 nm, a shift attributed to the polymer being incorporated into the pores.82 The size of the monomeric unit of the PDHS is about 1.6 nm, so only one polymer chain can be incorporated into a mesopore with a diameter of 2.8 nm. The narrow PL band at 350 nm is due to the reduction of the intermolecular interactions between polymer chains. This narrow PL band at 350 nm is assigned to the excited state of the linear polymer chain.81 Also, a new broad band of visible fluorescence at 410 nm appeared, which is assigned to localized states induced by conformational changes of the polymer chains caused by its interaction with the silanol (Si-OH) covered pore surface. Visible luminescence in nanosize PDHS is observed only when the polymer was incorporated in hexagonal pores of 2.8 nm and is not seen for the polymer incorporated into cubic pores of 2.8 nm diameter or hexagonal pores of 5.8 nm diameter. 

Abstract A concept of amphiphilicity in application to monomer units of water-soluble polymers is presented. Molecular simulation and experimental studies of polymers consisting of amphiphilic monomers units are reviewed. Those polymers reveal unusual conformational behavior in aqueous solutions forming nanostructures of nonspherical shape. Self-association of amphiphilic thermosensitive polymers in water solutions is discussed. Possibilities for the use of thermosensitive copolymers as catalysts are described. The sharp water-organic boundaries formed by polymer associates in water solutions are shown to be a prospective medium for catalysis owing to adsorption of interfacially active substrates at the interface. 

The present review has the following structure. In Sect. 2, the properties of amphiphilic monomers are discussed and a special classification of monomer units according to interfacial and partition properties is described. Also, the possibility of nanostructure formation in polymers composed of amphiphilic monomers is touched upon. This topic is more broadly treated in Sect. 3, where conformational properties of a key class of water-soluble polymers are... 

A new way of obtaining nanostructures in systems of thermosensitive polymers by combining them with hydrophilic species was proposed by Bron-stein et al. [54]. The core-shell nanoparticles were obtained by stabilization of the globular conformation of PVCL in aqueous solutions at 45 °C on add-... 

An alternative route to hybrid nanostructures with controlled release or mass transfer properties entails the modification of the pore network surface with photo-isomerizable molecules such as azobenzene (Fig. 18.5a). Azobenzene exists in two conformations, trans (the most stable isomer) and cis irradiation with light... 

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