  The formation of naturally-derived materials with wet stable fibrous
architectures is paramount in order to mimic the features of tissues at the
molecular and microscopic scale. Here, we investigated the formation of
wet-spun fibres based on collagen-derived polypeptides with comparable chemical
composition and varied molecular weight. Gelatin and hydrolysed fish collagen
(HFC) were selected as widely-available linear amino-acidic chains of high and
low molecular weight, respectively, and functionalised in the wet-spun fibre
state in order to preserve the material geometry in physiological conditions.
Wet-spun fibre diameter and morphology were dramatically affected depending on
the polypeptide molecular weight, wet-spinning solvent (i.e.
2,2,2-Trifluoroethanol and dimethyl sulfoxide) and coagulating medium (i.e.
acetone and ethanol), resulting in either bulky or porous internal geometry.
Dry-state tensile moduli were significantly enhanced in gelatin and HFC samples
following covalent crosslinking with activated 1,3 phenylenediacetic acid (Ph)
(E: 726 +/- 43 - 844 +/- 85 MPa), compared to samples crosslinked via
intramolecular carbodiimide-mediated condensation reaction (E: 588 +/- 38 MPa).
Resulting fibres displayed a dry diameter in the range of 238 +/- 18 - 355 +/-
28 micron and proved to be mechanically-stable (E: 230 kPa) following
equilibration with PBS, whilst a nearly-complete degradation was observed after
5-day incubation in physiological conditions.
