Figure 2.
(A) Type I collagen assembly in which the peptide chains (shown in red, blue and green), consisting of ~1000 amino acids, form triple helices ~100 nm in length and the blunt-ended nanofibres (shown in grey) assemble via the staggered lateral packing of the triple helices. The hydrogel pictured represents rat-tail collagen. (B) Self-assembly of collagen mimetic peptides, in which the peptides consist of 36 amino acids (shown in red, blue and green), form a triple helix staggered with a length of 10 nm and the nanofibres (shown in grey), and result from triple helical elongation, as well as from lateral packing. The hydrogel depicted is the synthetic peptide (Pro-Lys-Gly)4(Pro-Hyp-Gly)4(Asp-Hyp-Gly)4. (C–E) Transmission electron microscopy (TEM) images of collagen-like nanofibres taken at ×40,000. (F,G) Scanning electron microscopy (SEM) images of critical-point dried hydrogel with a peptide concentration of 1.0% by weight that shows the interconnected fibrous structure responsible for the gel forming properties at ×3100 (F) and ×30,000 (G). Adapted with permission from O’Leary et al. 2011 Copyright Nature publishing [114].