Chitosan cross-linking with a water-soluble, blocked diisocyanate. 1. Solid state

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Biochemistry

Background:

• Chitosan, a biopolymer, possesses desirable properties but requires modification for specific applications.
• Developing effective cross-linking strategies is crucial for enhancing chitosan's stability and functionality.

Purpose of the Study:

• To synthesize and evaluate a water-soluble cross-linking agent for chitosan.
• To investigate the effect of this cross-linking agent on chitosan's thermal, structural, and degradation properties.

Main Methods:

• Synthesis of a water-soluble, blocked-diisocyanate cross-linker.
• Cross-linking of chitosan films using varying NCO/NH(2) ratios.
• Characterization using Infrared spectroscopy (IR), Thermogravimetric analysis (TGA), swelling tests, and Wide-Angle X-ray Diffraction (WAXD).
• Enzymatic degradation studies using Chitinase.

Main Results:

• A stable, water-soluble diisocyanate adduct was successfully prepared.
• Chitosan cross-linking was achieved under mild thermal conditions (60°C for 24h) in a concentration-dependent manner.
• Spectroscopic and thermal analyses confirmed successful cross-linking.
• Cross-linking reduced enzymatic degradation by Chitinase, with efficiency limited by solid-state reaction mobility.

Conclusions:

• The developed cross-linking agent is effective for modifying chitosan.
• Cross-linked chitosan exhibits enhanced stability against enzymatic degradation.
• Further optimization may be needed to overcome solid-state reaction limitations for improved cross-linking efficiency.