Transient dynamic mechanical properties of resilin-based elastomeric hydrogels

Abstract

The outstanding high-frequency properties of emerging resilin-like polypeptides (RLPs) have motivated their development for vocal fold tissue regeneration and other applications. Recombinant RLP hydrogels show efficient gelation, tunable mechanical properties, and display excellent extensibility, but little has been reported about their transient mechanical properties. In this manuscript, we describe the transient mechanical behavior of new RLP hydrogels investigated via both sinusoidal oscillatory shear deformation and uniaxial tensile testing. Oscillatory stress relaxation and creep experiments confirm that RLP-based hydrogels display significantly reduced stress relaxation and improved strain recovery compared to PEG-based control hydrogels. Uniaxial tensile testing confirms the negligible hysteresis, reversible elasticity and superior resilience (up to 98%) of hydrated RLP hydrogels, with Young's modulus values that compare favorably with those previously reported for resilin and that mimic the tensile properties of the vocal fold ligament at low strain (<15%). These studies expand our understanding of the properties of these RLP materials under a variety of conditions, and confirm the unique applicability, for mechanically demanding tissue engineering applications, of a range of RLP hydrogels.

Microstructured Elastomer‐PEG Hydrogels via Kinetic Capture of Aqueous Liquid–Liquid Phase Separation

“…The RLPs were expressed following procedures extensively employed in the Kiick laboratories56, 57, 58, 59 and were functionalized with acrylamide groups to facilitate the desired on‐demand photo‐crosslinking of microscale domains. Chemical modification of RLP with N‐acryloxysuccinimide (NHS‐Ac) via reaction of lysine residues yielded RLP‐Ac ( Figure 1 A) via the protocols detailed in the Experimental Section.…”

Resilin-PEG Hybrid Hydrogels Yield Degradable Elastomeric Scaffolds with Heterogeneous Microstructure

“…Pure RLP hydrogels exhibited maximum strain values that are far greater (up to 400% strain) than these values for the RLP24-PEG hybrid hydrogels. 13, 14, 16 The use of PEG as a cross-linker in the hybrid hydrogels would not immediately suggest such a disparity in extensibility; in fact, wholly PEG hydrogels formed through step-polymerization cross-linking were extensible to 300% strain. 79 The disparities here may result, at least in part, from the fact that the RLP24-PEG hydrogels were more swollen and softer than the RLP hydrogels, and thus may have been more susceptible to damage when compressed by the metal clamps of the axial tensile geometry during sample loading.…”

“…25 In particular, recently developed resilin-like polypeptide (RLPs) hydrogels have been shown to form elastic materials that are stable, resilient, and highly extensible. 13, 14, 28 More recently, hybrid hydrogels, composed of recombinant elastomeric protein and PEG, have yielded materials in which encapsulated cells spread and adopt a spindle-like morphology. 17, 29 In addition, protein-PEG hydrogels comprising other proteins such as collagen 30–32 or fibrinogen, 30, 33–36 have been shown to improve biocompatibility and cell-matrix interaction.…”

Elastic proteins and elastomeric protein alloys

“…Charati et al . has reported RLP12, which contains 12 repeats of resilin consensus sequences from D. melanogaster , additional lysine residues outside the resilin repeat as crosslinking sites, the cell binding ligand RGDSP, heparin-binding domain and metalloproteinase sensitive domain to promote the proteolytic degradation [36,43,44]. Crosslinking of additional lysine residues in RLP12 by [tris (hydroxymethyl) phosphino] propionic acid via Mannich-type reaction results in hydrogels with elastic moduli of ∼ 15-60 kPa, an extensibility of 180%-335% and high-frequency responsiveness properties [36,43,45].…”