Multi-scale mechanical characterization of highly swollen photo-activated collagen hydrogels

• Published in: Journal of the Royal Society interface Vol. 12; no. 102; p. 20141079
• Main Authors: Tronci, Giuseppe, Grant, Colin A., Thomson, Neil H., Russell, Stephen J., Wood, David J.
• Format: Journal Article
• Language: English
• Published: England The Royal Society 06.01.2015
• Subjects: Anhydrides - chemistry; Animals; Atomic Force Microscopy; Biocompatible Materials - chemistry; Cell Line; Collagen; Collagen - chemistry; Compressive Strength; Covalent Network; Elastic Modulus; Elasticity; Epoxy Compounds - chemistry; Functionalization; Hydrogel; Hydrogels - chemistry; Materials Testing; Methacrylates - chemistry; Mice; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Photochemical Processes; Polystyrenes; Polyvinyls - chemistry; Pressure; Quaternary Ammonium Compounds; Rats; Stress, Mechanical; Structure-Activity Relationship; Swelling; Tissue Engineering - methods; functionalization; collagen; swelling; covalent network; atomic force microscopy; hydrogel
• ISSN: 1742-5689; 1742-5662
• DOI: 10.1098/rsif.2014.1079

Biological hydrogels have been increasingly sought after as wound dressings or scaffolds for regenerative medicine, owing to their inherent biofunctionality in biological environments. Especially in moist wound healing, the ideal material should absorb large amounts of wound exudate while 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 the nano- up to the macro-scale), uniquely high swelling ratios and retained (more than 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 (F: 16 ± 12–91 ± 7 mol%) of introduced moieties governed the structure–property relationships in resulting collagen networks, so that the swelling ratio (SR: 707 ± 51–1996 ± 182 wt%), bulk compressive modulus (Ec: 30 ± 7–168 ± 40 kPa) and atomic force microscopy elastic modulus (EAFM: 16 ± 2–387 ± 66 kPa) were readily adjusted. Because 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.