Hierarchical cell assemblies

Supramolecular systems offer distinct advantages as biomaterials over chemically cross-linked gels. First, because of their noncovalent nature, supramolecular systems are inherently responsive to stimuli such as variations in temperature and pH. Second, the noncovalent bonding allows a unique mix-and-match principle to be used for tuning properties. Third, supramolecular materials biodegrade faster than chemically cross-linked gels as a result of the small molecular precursors that these materials are made of. Furthermore, these supramolecular systems are proposed to be able to display dynamic reciprocal behavior, as found in the natural environment of cells [13]. Supramolecular biomaterials are proposed to be able to spatiotemporally adapt to changes exerted by cells and their natural environment. To fulfill this promise, important features of supramolecular systems are their hierarchical structure/assembly, their dynamic and nonlinear behavior, and then-biochemical properties. 

Cell assemblies. As macroporous templates, these provide a facile bioinspired method for the synthesis of hierarchical macro-mesoporous titania with tunable macroporous morphology and enhanced photocatalytic activity [134]. This is also a simple and facile technique that can be used to prepare many types of metal oxide porous materials with good control over the pore size and morphology. 

The formation of membrane structures and sacs such as seen in the cell can be achieved through hierarchical self-assembly... 

Three-dimensional (3D) polyaniline (PANI)-graphene nanoribbon (GNR)-carbon nanotube (CNT) composite, PANI-GNR-CNT, was prepared via in-situ polymerization of aniline monomer on the surface of a GNR-CNT hybrid. This hierarchical PANI-GNR-CNT composite with the two-electrode cell assembly showed much higher specific capacitance (890 F/g) than the GNR-CNT hybrid (195 F/g) and neat PANI (283 F/g) at a discharge current density of 0.5 A/g. This composite exhibited good cycling stability with a retention ratio of 89% after 1000 cycles [63]. 

Jones, E. M., and Surewicz, W. K. (2005). Fibril conformation as the basis of species- and strain-dependent seeding specificity of mammalian prion amyloids. Cell 121, 63-72. Kad, N. M., Myers, S. L., Smith, D. P., Smith, D. A., Radford, S. E., and Thomson, N. H. (2003). Hierarchical assembly of beta2-microglobulin amyloid in vitro revealed by atomic force microscopy./. Mol. Biol. 330, 785-797. 

In addition to their potential use as structural composites, these macroscopic assemblies of nanocarbons have shown promise as mechanical sensors [83], artificial muscles [84], capacitors [85], electrical wires [59], battery elements [85], dye-sensitized solar cells [86], transparent conductors [87], etc. What stands out is not only the wide range of properties of these type of materials but also the possibility of engineering them to produce such diverse structures, ranging from transparent films to woven fibers. This versatility derives from their hierarchical structure consisting of multiple nano building blocks that are assembled from bottom to top. 

The physiology of the body is assembled from the four hierarchical structures listed in order of increasing complexity cells, tissues, organs, and organ systems. The more complex structures are formed through aggregation of simpler structures. 

Although much of the interest in biological nanostructures has focused on relatively complex functionality, cells and organisms themselves can be considered as a collection of self-assembled materials lipid bilayers, the extracellular matrix, tendon and connective tissue, skin, spider silk, cotton fiber, wood, and bone are all self-assembled biological materials, with an internal structure hierarchically ordered from the molecular to the macroscopic scale. 

Hierarchic design of assembled structures should be important for preparation of functional mesoscopic structures. Typical examples can be seen in biological systems where tissues of organisms in living systems consist of assemblies of cells with cell membranes composed of self-assembled lipids, proteins, saccharides, etc. Therefore, tissues and organisms can be regarded as (at least) two-level assemblies lipid to... 

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