Structure and interactions in covalently and ionically crosslinked chitosan hydrogels for biomedical applications

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Chitosan hydrogels are widely explored for biomedical and pharmaceutical applications due to their biocompatibility.
• Understanding the crosslinking mechanisms is crucial for tailoring hydrogel properties for specific uses.

Purpose of the Study:

• To critically analyze covalently and ionically crosslinked chitosan hydrogels.
• To discuss the structural basis, synthesis, and chemistry of these hydrogels for pharmaceutical applications.

Main Methods:

• Review of literature on chitosan hydrogel formation via covalent and ionic crosslinking.
• Analysis of chemical interactions dictating gel network structures.
• Examination of pharmaceutical examples illustrating synthesis and properties.

Main Results:

• Covalently crosslinked chitosan hydrogels form permanent networks, enabling water/bioactive compound absorption and diffusion-based drug release.
• Ionically crosslinked chitosan hydrogels possess reversible links, exhibiting higher pH-sensitive swelling and potential for dissolution in extreme pH conditions.
• pH-controlled drug delivery can be achieved by incorporating additional polymers.

Conclusions:

• Both covalent and ionic crosslinking methods yield versatile chitosan hydrogels for medical applications.
• The choice of crosslinking strategy significantly impacts hydrogel stability, swelling behavior, and drug release profiles.
• Chitosan hydrogels offer tunable properties for advanced drug delivery systems and other pharmaceutical applications.