Dynamic Supramolecular Hydrogels Spanning an Unprecedented Range of Host-Guest Affinity

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Polymer Chemistry

Background:

• Cucurbit[7]uril (CB[7]) macrocycles are known for versatile host-guest binding.
• Supramolecular hydrogels offer dynamic network properties.
• Controlling network properties is crucial for advanced material applications.

Purpose of the Study:

• To investigate the impact of varying cross-link affinity on supramolecular hydrogel properties.
• To quantify the relationship between binding affinity and bulk material characteristics.
• To explore the influence of affinity on in vivo material behavior.

Main Methods:

• Synthesized 8-arm PEG macromers functionalized with CB[7] and complementary guests.
• Created supramolecular hydrogels with a wide range of cross-link affinities (1.5 × 10^7 to 5.4 × 10^12 M^-1).
• Characterized hydrogel dynamics, macromolecule release, and in vivo performance.

Main Results:

• Cross-link affinity directly correlates with hydrogel bulk properties, mimicking covalent gels at high affinities.
• Higher affinity led to slower relaxation and self-healing capabilities.
• Affinity significantly influenced the release rate of encapsulated macromolecules and in vivo cell infiltration and material clearance.

Conclusions:

• Cross-link affinity is a critical parameter for tuning supramolecular hydrogel properties.
• This study establishes a quantitative link between binding affinity and material performance.
• The findings provide a foundation for designing advanced supramolecular materials with predictable behaviors.