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

Abstract

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.

Bacterial Adhesion Is Affected by the Thickness and Stiffness of Poly(ethylene glycol) Hydrogels

“…Hydrated AFM is the optimal technique to study the local mechanical properties of fully hydrated soft hydrogels 27 since it does not introduce artifacts typically observed with scanning electron microscopy or dry AFM. 28–32 Because of their unique surface sensing mechanisms, 33,34 bacteria adhesion studies were conducted using two model microbes, non-motile gram-positive S. aureus and flagellated gram-negative E. coli . By combining well-controlled PEG hydrogel design parameters (antifouling chemistry, thickness, stiffness) with two distinct model bacteria we have formed a powerful platform to systematically evaluate if bacteria adhesion is affected by the thickness or amount of PEG concentration in a hydrogel coating.…”

Protease-sensitive atelocollagen hydrogels promote healing in a diabetic wound model

“…A 250 N load cell was operated up to complete sample compression. 34 Stress-strain curves were recorded and the compression modulus quantified as the slope of the plot linear region at 25-30% strain. Six replicates were employed for each composition.…”

“…Aquacel ® . 33,34,35 Wet stable fibres have also been produced by sequential wet-spinning of collagen triple helices and post-spinning covalent crosslinking with an aromatic diacid. 36,37,38 In light of these promising reports, we investigated in this study whether functional systems could be realised by building molecular architectures defined by the biochemical attributes of the chronic wound microenvironment in order to achieve accelerated healing in vivo.…”

Biocompatible Collagen Paramagnetic Scaffold for Controlled Drug Release

“…chitosan 17,18 and collagen 19 , which also show the capability to be enzymatically resorbed in vivo. It is well known that hydrogels can be obtained by either chemical or physical crosslinking methods.…”