Self-assembling biomaterials

Self-assembling injectable biomaterials also undergo gelation or phase-separation without chemical crosslinking reagents as described previously for environmentally responsive materials. Phase-separation of either hydrophobic bulk material or hydrophobic domains of amphiphilic molecules is a frequently applied mechanism by which self-assembly proceeds. 

In the bulk phase-separation approach, an organic solution of a polymer dissolved in a water-miscible solvent is injected into the tissue defect. After injection, the solvent diffuses away from the injection site, resulting in precipitation of the water-insoluble polymer. Selection of an appropriate solvent, which must be non-cytotoxic and not harmful to host tissue, is a key factor for success of the bulk phase-separation system. Two solvents that meet these criteria are N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). In recent years, improved strategies for removal of the solvent and release of growth factors have been active areas of investigation. However, the requirement of a solvent to induce phase separation of the polymer limits the scale at which this approach can be applied in vivo. Even for relatively biocompatible solvents such as NMP and DMSO, injection of large volumes is anticipated to adversely affect host tissue, as well as the ability to eliminate the solvent from the body. 

In recent years, self-assembly of amphiphiles with hydrophobic and hydrophilic domains has been investigated to create micro- and nano-structured 

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Bull SR, Guler MO, Bras RE et al (2005) Magnetic resonance imaging of self- assembled biomaterial scaffolds. Bioconjug Chem 16 1343-1348... 

Cellular Interactions with Self-assembled Biomaterials and Composites for Bone Tissue Engineering... 

Self-assembling Biomaterials for Scaffold Based Bone Tissue Regeneration... 

Due to many attractive properties, peptides are the most conunonly used building blocks and the most comprehensively understood for constructing self-assembled biomaterials. Peptides are reasonably tractable and scalable compared to other moiety for self-assembly and, in terms of biological functionality and flexibility, peptides are highly versatile and facile [3]. In most peptide-based self-assemblies, p-sheet and a-helix are frequently used for assembling nanostructures and, thus, become important basic structures for fabricating self-assembled nanostructures. 

Kyle S, Aggeli A, Ingham E, McPherson MJ. Production of self-assembling biomaterials for tissue engineering. Trends Biotechnol 2009 27 423-33. 

Kyle S, et al. (2009) Production of Self-Assembling Biomaterials for Tissue Engineering. Trends biotechnol. 27 p. 423-33. 

Hwang, J.J., Iyer, S.N., Li, L.-S., Claussen, R., Harrington, D.A., Stupp, S.I., 2002. Self-assembling biomaterials liquid crystal phases of cholesteryl oligo(L-lactic acid) and their interactions with cells. PNAS 99, 9662—9667. 

Development of modular self-assembling biomaterials is an attempt to harness the cell as the master-builder of its own extracellular matrix using tailored synthetic components. Biomaterial structures that are designed and built by human cells and their cellular components is only just being realized and is an important aim for future biomaterials for clinical applications. 

The use of modular self-assembling biomaterials for making equivalent structures to natural archetypes is a new approach. It simulates more accurately the way in which natural structures are constructed. In this proposal tailored modular elements are designed to be recognized by progenitor cells as matrix building blocks enabling them to be self-assembled by co-cultured cells into... 

J. H. Collier, Modular self-assembling biomaterials for directing cellular responses. Soft Matter 4,2310-2315 (2008). 

Rudra JS, Collier JH. 2.205-Self-assembling biomaterials. In Ducheyne P, editor. Comprehensive biomaterials. Oxford Elsevier, 2011. p. 77—94. 

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