Biomedical Engineering Reference
In-Depth Information
Fig. 1. Schematic representation of collagen synthesis process. Procollagen consists of a 300
nm long triple helical domain (comprised of three alpha-chains each of approximately 1000
residues) flanked by a trimeric globular C-propeptide domain and a trimeric N-propeptide
domain. Procollagen is secreted from cells and is converted into collagen by the removal of
the N- and C-propeptides by proteases. The collagen spontaneously self-assembles into
cross-striated fibrils that occur in the extracellular matrix of connective tissues. The fibrils
are stabilized by covalent crosslinking, which is initiated by oxidative deamination of
specific lysine and hydroxylysine residues in collagen by lysyl oxidase. (a) Scanning electron
microscopy image of a human fibroblast adhered on reconstituted salmon collagen fibrillar
matrix [17]. (b) Chemical structure of a collagen alpha-chain. (c) Atomic force microscopy
image of reconstituted salmon collagen fibril [17]. The repeating broad dark and light zones
(where D=67 nm, the characteristic axial periodicity of collagen) can be seen in the fibril.
salmon-derived collagen (SC) [24]. Additionally, heat denaturation of the bio-inspired
crosslinked SC gel provides elastic materials, which has the elongation of over 200% at break
point [24]. So far, the elasticity of the collagens that had been crosslinked “after”
fibrillogenesis is not as high as that crosslinked “during” fibrillogenesis (bio-inspired
crosslinking) [25]. This may indicate that the bio-inspired crosslinking confer intrafibrillar
