Table 3.

Advantages and limitations of modified methods of chitosan.

Cross-linking Method	Strength	Limit
Physical cross-linking	◆Safety of biomedicine Self-healing and injectable properties at room temperature	◆Reversible ◆Unstable Lack permanent junctions
Chemical cross-linking	◆Easy to operate ◆Stability ◆Excellent mechanical properties ◆Adjustable degradation properties Good cross-linking effect	◆Toxic cross-linking agents ◆Difficulty in sterilization Degree of cross-linking is not easy to control
Enzymatic cross-linking	◆Under normal physiological conditions ◆Highly biocompatible By modifying pH, temperature, or ionic strength, the cross-linking reaction can often be controlled	◆Substrate specificity Most expensive crosslinkers