A novel thermoresponsive hydrogel based on chitosan

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Injectable thermosetting chitosan hydrogels offer biodegradability, biocompatibility, and in situ implant formation.
• Thermally-induced gelation avoids toxic polymerization reactions common in other formulations.
• Sterilizability and long-term storage are crucial for biomedical applications.

Purpose of the Study:

• To investigate the sterilizability and storage stability of thermosetting chitosan hydrogels.
• To assess the impact of sterilization and storage methods on hydrogel properties.
• To develop a clinically applicable, storable, and injectable chitosan hydrogel formulation.

Main Methods:

• Chitosans from two sources were combined with phosphate-free polyols or polyoses.
• Autoclaving was used to assess sterilization effects on chitosan and hydrogel properties.
• Hydrogels were subjected to refrigeration and freezing to evaluate storage stability.
• Lyophilization with stabilizing agents (trehalose, mannitol) was explored for long-term storage.

Main Results:

• Autoclaving reduced chitosan molecular weight but retained desired thermosetting properties in hydrogels.
• Steam sterilization of chitosan followed by aseptic preparation yielded sterile hydrogels.
• Thermosetting hydrogels were unstable when refrigerated but stable when frozen.
• Lyophilized formulations with trehalose or mannitol were injectable and retained thermosetting properties.

Conclusions:

• Sterile chitosan hydrogels can be obtained through steam sterilization and aseptic processing.
• Freezing is a viable storage method for these thermosetting hydrogels.
• Lyophilization with specific stabilizers offers a promising route for developing clinically usable, long-term storable chitosan hydrogels.