Self-assembly concepts

Formation of Hposomal vesicles under controlled conditions of emulsification of Hpids with phosphoHpids has achieved prominence in the development of dmgs and cosmetics (42). Such vesicles are formed not only by phosphoHpids but also by certain nonionic emulsifying agents. Formation is further enhanced by use of specialized agitation equipment known as microfluidizers. The almost spontaneous formation of Hposomal vesicles arises from the self-assembly concepts of surfactant molecules (43). Vesicles of this type are unusual sustained-release disperse systems that have been widely promoted in the dmg and cosmetic industries. 

Composites with certain structural organization have been developed by approaching the self-assembly concept [13]. Electrostatic matching can be used to coat CNTs... 

The self-assembly concept also allows for the preparation of mixed lipid membranes that can offer a larger variety of lipid-based membranes with diverse functionalities that can be of interest in different technological applications [208]. These hybrid layers are composed of individual membrane leaflets of different molecules [209-211]. Such a hybrid interface has been assembled on sepiolite and was composed of an inner phosphatidylcholine mmiolayer (ML-PC)... 

Another self-assembly concept that provides a nanoscale linear template for protein and inorganic nanoparticles was developed by the Zuckermann group. For instance, they demonstrate a reversible molecular tool for assembly of modified peptides in the presence of divalent metal ions. The generated nanofibres could be disassembled by adding a strong metal-chelating reagent such as EDTA [38]. 

As organic compounds with an amphiphilic structure, they show solubility in both oils or organic solvents and water and, in fact, with respect to water, because these molecules have one hydrophilic and one hydrophobic part, they are pushed toward the areas of contact, concentrating at the interfaces between air (or oil) and water through the adsorption process. Further insight on the self-assembly and self-organization including surfactants in liquids can be found in Introduction to Surfactant Self-Assembly, Concepts, Soft Matter Science—a Historical Overview with a Supramolecular Perspective and Self-Assembly of Facial Amphiphiles in Water, Soft Matter, respectively. 

Abstract Recent advances in synthetic aspects of the rhodium-catalyzed hydroformylation of alkenes are reviewed. Emphasis is given to practical improvements, efficient new catalysts for regioselective and enantioselective hydroformylation, and to applications of the reaction in organic synthesis. Furthermore, new developments in directed hydroformylation are covered as well as new approaches toward efficient hydroformylation catalysts employing the concept of self-assembly. 

The formation of polymeric capsules can also be achieved by the cross-linking of self-assembled amphiphilic block copolymers [85]. The hydrophobic section of the polymer in an aqueous solution will tend to aggregate on the interior of the micelle, whereas the hydrophilic ends will form the outer shell of the micelle. If the hydrophilic end is appropriately functionalized, it can be cross-linked, giving a polymeric shell. The overarching concept is shown in Figure 5.10. 

Thus, the concept and manifestation of molecular recognition mediated supramolecular self-assembly of small chemical units, be it an ABn type building block or a dendrimer molecule, have proved to be vital factors in bridging the gap between small molecules and novel new-age materials. 

More recently, a new method of assembling multilayers of PB on surfaces has been described.110 In contrast to the familiar process of self-assembly, which is spontaneous and leads to single monolayers, directed assembly is driven by the experimenter and leads to extended multilayers. In a proof-of-concept experiment, the generation of multilayers of Prussian blue (and the mixed Fein/Run analog ruthenium purple) on gold surfaces by exposing them alternately to positively charged ferric cations and [Fe(CN)6]4- or [Ru(CN)f,]4 anions has been demonstrated.110... 

G. Thoma, M. B. Streiff, A. G. Katopodis, R. O. Duthaler, N. H. Voelcker, C. Ehrhardt, and C. Masson, Non-covalent polyvalent ligands by self-assembly of small glycodendrimers A novel concept for the inhibition of polyvalent carbohydrate-protein interactions in vitro and in vivo, Chem. Eur. J., 12 (2006) 99-117. 

Davis ME (2009) The first targeted delivery of siRNA in humans via a self-assembling, cyclodextrin polymer-based nanoparticle from concept to clinic. Mol Pharmaceutics 6 659-668... 

The basic concept behind all models of chiral self-assembly can be stated as follows. In general, chiral molecules do not pack parallel to their neighbors but rather pack at a slight angle with respect to their neighbors. This favored packing can be visualized by the packing of hard screws,6 as illustrated in... 

Abstract Chemists may find it difficult to admit that their concepts and opportunities have always been strongly influenced by the available methods for characterization and analysis. Physics, has, of course, the lead when it comes to the visualization of single molecules in real space and to the detection of their specific, not ensemble-averaged properties. The challenge for chemistry is to provide molecules as objects of study which really disclose new concepts of structure and function. This chapter presents a chemical approach toward nanosciences which comprises (i) design and synthesis, (ii) immobilization, often using principles of self-assembly, (iii) visualization, e.g. by scanning probe... 

---