Table 1.

Natural hydrogel’s gelation methods

Gelation method	Hydrogel origin	References
Physical methods
Temperature increase	Chitosan	[78–80]
	Collagen
Cryogelation	Silk	[81]
Chemical methods
Crosslinkers	Chondoritin	[27]
	Hyaluronic acid	[82]
	Gelatin	[81]
Cation adding	Alginate	[83]