Local, micromechanical environment is known to influence cellular function in heterogeneous hydrogels, and knowledge gained in micromechanics will facilitate the improved design of biomaterials for tissue regeneration. In this study, a system comprising microstructured resilin‐like polypeptide (RLP)–poly(ethylene glycol) (PEG) hydrogels is utilized. The micromechanical properties of RLP‐PEG hydrogels are evaluated with oscillatory shear rheometry, compression dynamic mechanic analysis, small‐strain microindentation, and large‐strain indentation and puncture over a range of different deformation length scales. The measured elastic moduli are consistent with volume averaging models, indicating that volume fraction, not domain size, plays a dominant role in determining the low strain mechanical response. Large‐strain indentation under a confocal microscope enables the visualization of the microstructured hydrogel micromechanical deformation, emphasizing the translation, rotation, and deformation of RLP‐rich domains. The fracture initiation energy results demonstrate that failure of the composite hydrogels is controlled by the RLP‐rich phase, and their independence with domain size suggested that failure initiation is controlled by multiple domains within the strained volume. This approach and findings provide new quantitative insight into the micromechanical response of soft hydrogel composites and highlight the opportunities in employing these methods to understand the physical origins of mechanical properties of soft synthetic and biological materials.
When hydrogels are designed for biological applications, the mechanical properties are carefully chosen to match their precise application. However, traditional methodologies of mechanical characterization (simple shear or compression/extension) commonly ignore the multiaxiality of in vivo deformations. A recent study highlights that biopolymers and tissue indeed show a complex response to combined uniaxial and shear strains. In this study a synthetic yet biomimetic fibrous hydrogel is used, which is based on polyisocyanides and forms a self‐assembled network of branched semiflexible chains, similar in architecture networks of structural biopolymers like actin, collagen, and fibrin. Its synthetic nature allows to decouple key parameters of these networks and individually understand their impact on the mechanical response under multiaxial deformation. Experimentally, it is found that the persistence length is a key parameter of biological networks, which tunes softening of gels under compression: The stiffer the polymer, the more the network softens in compression. This study provides insights into tissue behavior that likely is only obtainable from synthetic model systems and is able to direct further the design of new synthetic biomimetic soft materials that are in high demand as tunable bio‐free extracellular matrix materials.
more » « less- NSF-PAR ID:
- 10376165
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 31
- Issue:
- 18
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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