Using Stereochemistry to Control Mechanical Properties in Thiol-Yne Click-Hydrogels

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials Engineering

Background:

• Stereochemistry profoundly influences polymer mechanical properties, particularly in thermoplastics.
• Limited research exists on stereochemistry's effect on swollen polymer networks like hydrogels.
• Conventional methods to alter hydrogel stiffness often change other physical properties, confounding cellular response studies.

Purpose of the Study:

• To investigate the impact of stereochemistry on hydrogel bulk properties.
• To develop a method for tuning hydrogel mechanical properties independently of other physical characteristics.
• To create a platform for studying cell mechanotransduction without confounding variables.

Main Methods:

• In situ formation of a double bond during click-hydrogel gelation.
• Manipulation of the stereochemistry (cis/trans ratio) of the formed double bond.
• Mechanical characterization of hydrogels with varying stereochemistry.
• Utilizing human mesenchymal stem cells as a substrate stiffness reporter.

Main Results:

• Hydrogels with high trans content were approximately 3 times stiffer than their cis analogues.
• Diverse mechanical properties were achieved while maintaining comparable physical properties.
• Demonstrated the ability to decouple stiffness from other physical parameters.

Conclusions:

• Stereochemistry is a powerful tool for tuning hydrogel mechanical properties independently.
• These stereochemically controlled hydrogels provide a novel platform for mechanotransduction research.
• The findings offer new possibilities for designing biomaterials with tailored mechanical cues for cell studies.