Hydrogelating self-assembling fibers

Alternative to fibers and 2D and 3D woven or nonwoven networks thereof formed as either self-supporting structures or as a hydrogel, it is possible to self-assemble peptides into thin self-assembled monolayers (SAMS) or multilayer structures. Such structures have been reported to act as membranes for controlled diffusion of ions and controlled movement of body fluids and contaminants (Ellis-Behnke et al., 2006, 2007 Holmes et al., 1999). Alternatively, various techniques have been put in place to provide coatings on various substrates ranging from tissue to metals and inorganics, for example, mica (Boden et al., 2002 Haynie, 2005,2007 Haynie and Zhi, 2007 Yoo et al., 2008). 

The liquid gelators, Span 80-Tween 80 also forms emulsion organogels and emulsion hydrogels by fluid-filled fiber mechanism. It has been reported that Span 80 (sorbitan monooleate) and Tween 80 (polyoxyethylene sorbitan monooleate) mixed in the ratio of 1 2 w/w forms organogel with better firmness and architecture as compared to the other surfactant mixture ratios.When water is added dropwise into the homogenous surfactant mixture and oil, it forms spherical reverse-micellar droplets. These droplets/fibers self-assemble to form three-dimensional architecture to immobilize apolar solvent. " Similarly, in case of hydrogels micellar structures are formed, which entraps the external liquid phase to flow and form hydrogel. 

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...

Figure 6.7 Protein-based self-assembled nanomaterials and fabrication strategies (a) structure of coiled-coil polypeptide, (b) association of the end helices into coiled-coils results in hydrogel formation, (c) amphiphilic block copolymers assemble into extended tapered end fibers, forming hydrogels, and (d) association of two-component proteins to form a hydrogel. Modified firom Ref. [3] with permission.

SCI in adult rats (Novikov et al. 2002). PHB fibers demonstrated improved neuronal survival in comparison with the implantation of only alginate hydrogel or fibronectin. Novikova et al. demonstrated PHB scaffold seeded with Schwann cells significantly promote spinal cord repair (Novikova et al. 2008). Silk (Uebersax et al. 2007), chitosan (Nomura et al. 2008 Li et al. 2009), self-assembling peptide nanofibers (Guo et al. 2009), and hyaluronic acid (Wang and Spector 2009) are more examples of natural materials that have been examined in spinal cord research. 

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