Modular degradable hydrogels based on thiol-reactive oxanorbornadiene linkers

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials

Background:

• Oxanorbornadiene dicarboxylate (OND) reagents are effective Michael acceptors.
• Their adducts fragment via retro-Diels-Alder reactions at controllable rates.
• This property is valuable for designing degradable materials.

Purpose of the Study:

• To synthesize and characterize self-supporting hydrogels using OND linkers.
• To investigate the degradation kinetics and physical properties of these hydrogels.
• To explore the potential of OND-based hydrogels for sustained cargo release.

Main Methods:

• Conjugate addition reactions between thiol-terminated tetravalent PEG and multivalent ONDs.
• Assessment of gelation time, erosion rates, and physical properties (swelling behavior).
• Evaluation of cargo diffusion and release profiles based on hydrogel degradation and cargo size.

Main Results:

• Rapid formation (within 1 min) of self-supporting hydrogels at physiological conditions.
• Predictable, pH-independent hydrogel erosion over minutes to weeks.
• Tunable degradation by modifying OND linker substitution.
• Comparable physical properties for hydrogels with equal valence OND linkers.
• Cargo release rates dependent on hydrogel degradation and cargo size.

Conclusions:

• OND linkers are highly effective for creating rapidly forming, degradable hydrogels.
• These hydrogels exhibit tunable erosion rates and predictable physical properties.
• The OND-based hydrogels show significant promise for sustained release applications.