Self-assembled system, applications

For technological applications it is highly desirable to be able to design self-assembling systems to have particular physico-chemical properties under a given set of experimental conditions. Using computer simulation, it is possible to construct an atomistic model of tapes, ribbons and fibrils to study all of the interatomic interactions within the system in a quantitative manner. Figure 13 shows atomistic... 

DD can be monitored by a variety of experimental techniques. They involve thermodynamic, dilatometric, and spectroscopic procedures. Molecular dynamics (MD) simulations also become applicable to self-assembled systems to some extent see the review in Ref. 2. Spectroscopic methods provide us with molecular parameters, as compared with thermodynamic ones on the macroscopic level. The fluorescence probing method is very sensitive (pM to nM M = moldm ) and informs us of the molecular environment around the probes. However, fluorescent molecules are a kind of drug and the membrane... 

Recently, biodegradable polymers have been used to fabricate macro- and nanometer scale self-assembled systems such as microspheres (MSs), nanospheres (NSs), polymer micelles, nanogels, and polymersomes (Fig. 1). These have attracted growing interest because of their potential utility for drug delivery systems (DDS), tissue engineering, and other applications. To construct these self-assembled systems... 

Tomalia, D. A. in Walsh, B. (ed.), Non-Viral Genetic Therapeutics Advances, Chal-langes and Applications for Self-Assembling Systems, IBC USA Conferences, Inc., Westborough, MA, 1996, pp. 1.2-1.2.36. 

In another case, PAs were designed to function as magnetic resonance imaging (MRI) contrast agents (Bull et al. 2005) by covalently linking the peptide portion to a derivative of l,4,7,10-tetraazacyclododecane-l,4,7,10-tetraacetic acid followed by chelation of Gd ions by this moiety. The PAs were modified such that self-assembly produce either nanofibers or spherical micelles. The application of this self-assembling system could be extended to noninvasive MRI of PA scaffolds in vivo. 

The use of specific interactions to control polymer structure and properties is a rapidly emerging field. We have assembled a group of authors at the forefront of this field that are smdying both the fundamental science inherent in polymer self-assembly and applications of this strategy to functional systems. This book is designed for researchers in a wide range of areas, and features both fundamental aspects and applications of these fascinating systems. 

Detailed information, background reviews, or highlights from the authors about the specific properties of PFCs and fluorinated colloids in relation to biomedical applications can be found in Refs. [3-9]. These papers also provide insight into the surface properties of PFCs, their hydrophobic and lipophobic characters, self-aggregation properties, tendency to stabilize interfaces, and ability to promote nanocompartmentation in self-assembled systems. 

Hence, fluorous liquid crystal self assembly is an attractive area with importance for numerous practical applications and for the general understanding of the development of complexity in self-assembled systems. It is connected to other fields of soft matter research such as compartmentation of micelles and membranes... 

Mechanically interlocked molecular compounds, including catenanes, rotax-anes, and carceplex, are constituted of molecules composed of two or more components that cannot be separated from each other [95-98]. The development of strategy for achieving controlled self-assembling systems by non-covalent interaction enables one to prepare such attractive compounds for applications in nanoscale molecular devices. The dithiafulvene derivatives are effective electron donors, which are good candidates to form those supramolecular systems with appropriate acceptors by virtue of intermolec-ular CT interactions. In this chapter, dithiafulvene polymers forming rotax-ane structures are especially described. 

The examples highlighted in this section illustrate the broad applicability of fibrils and other self-assembling systems as components in biosensors... 

While supramolecular chemistry of porphyrins has been extensively studied over the last few decades, related study of phthalocyanines is still in its infancy. Despite the great potential of phthalocyanine-based supramolecular arrays in various applications as mentioned earlier, only a handful systems have been reported so far. Self-assembled systems held by hydrogen bonding, donor-acceptor interactions, and host-guest interactions are still very rare. There is certainly much room for further investigation in the chemistry of this important class of compounds, particularly on their structural and functional aspects. We hope this article can provide the grounding for further studies. 

The practical use of self-assembled systems in technological applications requires that the supramolecular assembly survive and function under a variety of conditions. Another strategy for obtaining stability is by polymerization of the microstructures following self-assembly. There have been intensive studies in this area.45,46 Fatty acids with polymerizable groups have been used to prepare polymerizable... 

Models with increasing sophistication for the analysis of dynamic processes in supramolecular systems, notably micelles, as well as for the determination of other parameters have been developed over the past two decades. The basic conceptual framework has been described early on [59,60,95,96] and has been classifred into different cases which take into account the extent of quencher mobility and the mechanism of quenching [95]. Two of those cases lead to information about mobility and will be discussed. It is important to emphasize that this analysis is only applicable to self-assembled system such as micelles and vesicles it cannot be applied to host-guest complexes. This model assumes that the probe is exclusively bound to the supramolecular system and that no probe migration occurs during its excited state lifetime. The distribution of probe and quencher has been modeled by different statistical distributions, but in most cases, data are consistent with a Poisson distribution. The Poisson distribution implies that the quencher association/dissociation rate constants to/from the supramolecular system does not depend on how many... 

The second example concerns the multidisciplinary study of the micelliz-ing block copolymer polystyrene-( -poly(2-vinylpyridine)-ft-poly(ethylene oxide) (PS-PVP-PEO), which shows a high tendency to aggregation and the formation of micellar clusters [88,89]. It shows the application of SRM for studying the mobility and structural details of different domains in micelle-like polymeric nanoparticles. The fluorescence technique reveals interesting features of studied systems that are hardly accessible by other techniques. Section 3.3 is devoted to the development of the methodology of the solvent relaxation technique for studying nanostructured self-assembling systems. 

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