Nature self-assembly

Self-assembly is the spontaneous organization of molecules into stable, well-defined structures with the driving forces being noncovalent associations. The final structure is normally near or at the thermodynamic equilibrium arrangement allowing it to form spontaneously. Such formations can be done under conditions where defects are either minimized or eliminated. In nature, self-assembly is common as in the folding of proteins, formation of the DNA double helix, etc. 

In Nature, self-assembly to form finite assemblies often involves the non-covalent organization of molecules containing not only amphiphilic character, but also specific information needed for additional intermolecular recognition processes to occur, e.g., hydrogen... 

As scientists and engineers, natural self-assembly processes represent a tremendous resource, which we can use to create our own miniature materials and devices. Our endeavors are informed by hundreds of years of curiosity-driven research interested in the natural world. Our toolbox is further expanded by modem synthetic chemistry which extends beyond the realm of natural molecules. We can also create artificial environments to control and direct assembly and use computer-based tools and simulations to model and predict self-assembly pathways and their resulting protein structures. Many researchers believe we can use these modern tools to simplify, improve, and refine assembly processes. We have much to do in order to reach this ambitious goal but the next 10 years are likely to be filled with exciting discoveries and advances as self-assembling polypeptide materials move from the laboratory to the clinic or the manufacturing assembly line. 

The present discussion [47] deals with the formation of natural self-assembly of CuS nanoclusters in dielectric substrates of gum Arabica biopolymer. Low concentration of ammonium complex of copper oxide solution was dissolved in gum Acacia Arabica solution at 60°C and stirred. H2S gas was passed in the same environment for 1 minute. Heating the resulting solution to about 100°C evaporates any possible trace of ammonia. The resulting nanocomplex was caste in the form of very thin film by spin coating technique. The developed specimen was used for experimental investigations, namely TEM, XRD, and electrical experiments such as impedance spectroscopy, and the Arrhenius plot and I-V characteristics were measured in the applied field direction perpendicular to the 2-D plane. 

Self-assembly is the spontaneous, noncovalent association of two or more molecules under equilibrium conditions into stable, well-defined aggregates. In nature, self-assembly is a ubiquitous strategy responsible for the formation of cell membranes, double-stranded nucleic acids, and viruses. In chemistry, self-assembly offers a rapid way to construct receptors, catalysts, and materials. With appropriate curvature and careful positioning of self-complementary bonding sites, self-assembling systems generate capsules. 

In this chapter we study the overview of the various naturally and artificially prepared self-assembled nanostructures which are currently very important and in demand in biomedical applications, for example, bone tissues, natural laminated composites present in sea shells, peptide chain arrays and their derivatives and cell membranes are naturally self-assembled materials. And Langmuir—Blodgett films, surfactant-directed nonporous materials, and molecularly directed films, composites, nanombes, nanofibrils, nanowires, spherical vesicles, and template-assisted growth are artificially prepared self-assembled nanostructures. Here we discuss in brief the synthesis of those nanostructures which exist in nature and are prepared artificially to fulfill certain requirements (Figure 2.1). 

Similar to the concept of nanomaterials, the concept of self-assembly is not new. Nature has always evolved natural self-assembly mechanisms. However, it took us a long time to identify the process (Ozin et al., 2009). 

The interest in nanostmctures extends beyond their individual properties. We have learned to exploit the natural self-assembly of atoms/molecules into crystals. The directed self-assembly of nanostructures into more conqilex, hierarchical systems is also an important goal. Without direct self-assembly, manu cturing costs will severely limit the nanotechnology impact... 

Actin Collagen Fibre Fracture Hydrophobic bond Myosin Nature Self-assembly Silk Smart composite Structural hierarchy Toughness... 

We have reflected on several issues that are important to fracture characterisation and control in the context of natural self-assembled fibrous materials. To conclude this discussion, it is appropriate to consider some of nature s best examples of optimisation and versatility in fibre-reinforced composites sea cucumber body and the catch ligament associated with the ball-and-socket joint at the base of the sea urchin spine (Fig. 7). These materials are among the living world s oldest fibrous composites, which is testimony to their successful design. They offer several time-tested and thought-provoking lessons for the materials engineer. 

Pelesko, John A. Self Assembly The Science of Things That Put Themselves Together. Boca Raton, Ela. Chapman and Hall/CRG, 2007. Discusses natural self-assembling systems such as crystals and soap films and goes on to discuss viruses and self-assembly of DNA cubes and electronic circuits. Excellent introduction to a field of growing importance. 

Synthetic self-assembled scaffolds allow for development of biomimetics that have tailored stabilities and sizes. Peptides have the advantages of inherent biocompatibility and of remarkable diversity regarding functionality and ligand orientations. The virus scaffolds have natural self-assembly features for protein cages in a wide variety of sizes and architectures. 

We noted above that one reason the hydrophobic effect is so important is that it provides a way for the spontaneous assembly of many molecules into a more complex, (partially) ordered structure. In pure aqueous media, neither hydrogen bonding, ion pairing, nor the cat-ion-TT interaction can accomplish this alone. Nevertheless, nature self-assembles more complicated structures than just micelles and vesicles. Especially impressive are structures such as tobacco mosaic virus, in which exactly 2130 identical copies of a protein spontaneously assemble around a strand of RNA to make a 3000 A long virus or the ribosome, in which over 50 different proteins and thousands of nucleotides of RNA co-assemble into a remarkable molecular machine that executes protein synthesis. 

Natural Self-Assembling Chlorins the Chlorosomal Bacteriochlorophylls. 13... 

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