Nanostructured organic biomaterials

A Soft Method for Developing Nanostructured Organic Biomaterials... 

Introducing chirality into polymers has distinctive advantages over the use of nonchiral or atactic polymers because it adds a higher level of complexity, allowing for the formation of hierarchically organized materials. This may have benefits in high-end applications such as nanostructured materials, biomaterials, and electronic materials. Synthetically, chiral polymers are typically accessed by two methods. Firstly, optically active monomers - often obtained from natural sources - are polymerized to afford chiral polymers. Secondly, chiral catalysts are applied that induce a preferred helicity or tacticity into the polymer backbone or activate preferably one of the enantiomers [59-64]. 

Such highly organized assemblies may also be used as templates for the synthesis of new nanostructures and biomaterials. For example, Sreenivasach-ary and Lehn recently prepared dynamic hydrogels by covalent modification of the 5 -sidechains that extend from stacked G-quartets. Reaction of a hydrogel A made from 5 -hydrazido G 2 with a mixture of aldehydes produced a family of acylhydrazone G-quartets (Figure 3). This dynamic library of acylhydrazones demonstrated preferential synthesis of the most stable hydrogel... 

Composites made with carbon nanostructures have demonstrated their high performance as biomaterials, basically applied in the field of tissue regeneration with excellent results. For example, P.R. Supronowicz et al. demonstrated that nanocomposites fabricated with polylactic acid and CNTs can be used to expose cells to electrical stimulation, thus promoting osteoblast functions that are responsible for the chemical composition of the organic and inorganic phases of bone [277]. MacDonald et al. prepared composites containing a collagen matrix CNTs and found that CNTs do not affect the cell viability or cell proliferation [278]. 

The CBBCs including Ca-aluminate based biomaterials can be produced at low temperatures in-situ, in vivo. The chemistry of these systems is similar to that of hard tissue in living organisms. The CBBCs easily form nanostructures with crystal sizes similar to those found in hard tissue. Both stable and resorbable CBBCs can be produced. The stable phases are found within the Ca0-Al203-H2O and Ca0-Si02-H20 systems, while resoibable phases are seen within the Ca0-P205-H20 system and within sulphate systems. 

The paper is organized in three parts. First, the effects of nanoconfinement on the structure of the sol-gel trapped biomolecule are discussed. Second, from the results on apparent reactivity of these biomaterials, the effects of the matrix on the reactivity of trapped enzyme are elucidated. Finally, the interaction of the confined biomolecules with exogenous ligands/substrates and the applications of these materials in the area of molecular biorecognition are discussed. The reaction chemistries of biologically active molecules in die nanostructured materials have been crucial in establishing the role of the matrix upon the structure and reactivity of the confined proteins. 

Many researchers try to exploit polymer composites manufacturing techniques in order to tailor/improve the performance of collagen as biomaterial. In 2001, Kikuchi et al, have succeeded in manufacturing implants of HAp/collagen with a self-organized nanostructure and composition similar to bone. These implants... 

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