Hydrogels peptide amphiphiles

Fig. 1 Supramolecular systems described in this chapter. Top-. The extracellular matrix inspires most of the work and consists of fibers to resist tensile stresses such as collagens, fibers to resist compressive stresses such as the glycosaminoglycans, and soluble factors for cell signalling. Bottom Natural systems such as collagen, coiled-coil structures, p-sheet peptides such as peptide amphiphiles and multidomain peptides, hybrid systems such as streptavadin-biotin cross-linked microparticles, and synthetic systems such as the UPy-based hydrogelators...

Fig. 4 Self-assembling hydrogelators based on p-sheets. (a) Representative chemical structure of a peptide amphiphile, here without charged residues and with a heparin binding domain, (b) Peptide amphiphile with bioactive epitopes left) and its assembly leading to formation of ID fibers right). Reprinted from [136], Copyright 2010, with permission from Elsevier, (c) Graph showing the enhanced functional recovery for animals treated with the peptide amphiphile, as assessed via the BBB score. Adapted with permission from [78]. Copyright 2008 Society for...

Mitra, R. and Das, P. 2008. In-situ preparation of gold nanoparticles of varying shape in molecular hydrogel of peptide amphiphiles. /. Phys. Chem. C 112 8159-8166. 

Debnath S, Shome A, Das D et al. Hydrogelation through self-assembly of Fmoc-peptide functionalized cationic amphiphiles potent antibacterial agent. J Phys Chem B 114 4407-4415... 

Figure 20.10. Amphiphilic ionic self-complementary peptides. This class of peptides has 16 amino acids, c. 5 nm in size, with an alternating polar and non-polar pattern. They form stable (3-strand and 3-sheet structures thus, the side chains partition into two sides, one polar and the other non-polar. They undergo self-assembly to form nanofibers with the non-polar residues inside positively and negatively charged residues form complementary ionic interactions, like a checkerboard. These nanofibers form interwoven matrices that further form a scaffold hydrogel with a very high water content ( 99.5%). The simplest peptide scaffold may form compartments to separate molecules into localized places where they can not only have high concentration, but also form a molecular gradient, one of the key prerequisites for prebiotic molecular evolution.

In another research, an approach by using proteases, enzymes that normally hydrolyze peptide bonds in aqueous medium, to perform the reverse reaction (i.e., peptide synthesis or reversed hydrolysis) to produce amphiphilic peptide hydrog-elators that self-assemble to form nanofibrous stmctures was proposed by Ulijin et al. As shown in Fig. 3.34, Fmoc-amino acids (44) and peptides (45) could reacted to form hydrogelator 46 catalyzed by thermolysin (or chymotrypsin), which was able to form transparent gels in water. The result demonstrates that a protease can be used to selectively trigger the self-assembly of peptide hydrogels via reversed hydrolysis [84]. 

Amphiphilic peptides lonically crosslinked micro- and nano-spheres Biotinylated microspheres Photopolymerizable hydrogels Thermally activated crosslinked gels Two-component polyurethanes Alginates... 

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