  Biological hydrogels have been increasingly sought after as e.g. wound
dressings or scaffolds for regenerative medicine, due to their inherent
biofunctionality in biological environments. Especially in moist wound healing,
the ideal material should absorb large amounts of wound exudate whilst
remaining mechanically competent in-situ. Despite their large hydration,
however, current biological hydrogels still leave much to be desired in terms
of mechanical properties in physiological conditions. To address this
challenge, a multi-scale approach is presented for the synthetic design of
cyto-compatible collagen hydrogels with tunable mechanical properties (from
nano- up to the macro-scale), uniquely high swelling ratios and retained (>70%)
triple-helical features. Type I collagen was covalently functionalized with
three different monomers, i.e. 4 vinylbenzyl chloride, glycidyl methacrylate
and methacrylic anhydride, respectively. Backbone rigidity, hydrogen-bonding
capability and degree of functionalization (<i>F</i>: 16&plusmn12 &ndash
91&plusmn7 mol.-%) of introduced moieties governed the structure-property
relationships in resulting collagen networks, so that the swelling ratio
(<i>SR</i>: 707&plusmn51 &ndash 1996&plusmn182 wt.-%), bulk compressive modulus
(<i>E<sub>c</sub></i>: 30&plusmn7 &ndash 168&plusmn40 kPa) and Atomic Force
Microscopy elastic modulus (<i>E<sub>AFM</sub></i>: 16&plusmn2 &ndash
387&plusmn66 kPa) were readily adjusted. In light of their remarkably high
swelling and mechanical properties, these tunable collagen hydrogels may be
further exploited for the design of advanced dressings for chronic wound care.
