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Wet-spinnability and crosslinked fibre properties of two collagen polypeptides with varied molecular weight

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.