Simultaneously physically and chemically gelling polymer system utilizing a poly(NIPAAm-co-cysteamine)-based...

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Chemical Engineering

Background:

• Developing advanced hydrogels for in vivo applications requires materials with enhanced mechanical properties and controlled cross-linking.
• Existing thermosensitive physical gels often lack the necessary stability for long-term functional replacement.

Purpose of the Study:

• To create an in situ physically and chemically cross-linking hydrogel for in vivo applications.
• To investigate the properties and potential applications of a novel dual-crosslinking hydrogel system.

Main Methods:

• N-Isopropylacrylamide (NIPAAm) was copolymerized with N-acryloxysuccinimide (NASI) via free radical polymerization.
• Poly(NIPAAm-co-NASI) was modified with cysteamine to create poly(NIPAAm-co-cysteamine).
• Nuclear magnetic resonance (NMR) was used for modification verification. Dual gelation was achieved via physical cross-linking (thermoresponsive) and chemical cross-linking (Michael-type addition with poly(ethylene glycol) diacrylate).

Main Results:

• The dual-crosslinking hydrogel exhibited significantly improved material properties compared to purely physical gels.
• Chemical gelation time was independent of thiol content due to increased pKa.
• Swelling behavior was dependent on temperature and thiol content.
• Nucleophilic attack rate was sensitive to pH and thiol to acrylate mole ratio.

Conclusions:

• The developed hydrogel offers superior mechanical properties for potential long-term functional replacement applications.
• Further development and biocompatibility testing could enable its use as a temperature-responsive injectable biomaterial for functional embolization.