Crosslinker Architectures Impact Viscoelasticity in Dynamic Covalent Hydrogels

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Mechanobiology

Background:

• Dynamic covalent crosslinked (DCC) hydrogels mimic in vivo tissue mechanics.
• Their viscoelasticity and self-healing properties are crucial for regenerative medicine.
• Crosslinker architecture's impact on DCC hydrogel properties remains under-explored.

Purpose of the Study:

• Investigate the influence of side-chain versus telechelic crosslinker architectures on DCC hydrogel properties.
• Examine hydrazone-based alginate hydrogels to understand structure-property relationships.
• Provide insights for designing DCC hydrogels with tailored mechanical characteristics.

Main Methods:

• Synthesized hydrazone-based alginate hydrogels with varying crosslinker architectures (side-chain, linear telechelic, star telechelic).
• Characterized hydrogel viscoelasticity and stiffness through mechanical testing.
• Analyzed the effects of polymer concentration, crosslinker stoichiometry, and valency.

Main Results:

• Side-chain crosslinking (SCX) stiffness increases with polymer concentration; off-stoichiometry reduces stiffness and relaxation time.
• Telechelic crosslinking shows maximal stiffness and slowest relaxation at intermediate concentrations, enhanced by higher valency.
• Star crosslinking (SX) yields greater stiffness and slower relaxation than linear crosslinking (LX), with improved robustness.

Conclusions:

• Crosslinker architecture is pivotal in determining DCC hydrogel stiffness and viscoelasticity.
• SCX hydrogels exhibit slower stress relaxation, while SX hydrogels offer enhanced stiffness and robustness.
• Findings guide the rational design of DCC hydrogels for specific biomedical applications.