Table 2.

The preparation methods of cyclodextrin-containing hydrogels.

Types	Matrix	Preparation Methods	Characteristic	Ref.
Physically cross-linked cyclodextrin-containing hydrogels	Chitosan	Casting method	Bilayer hydrogels	[48]
	Chitosan	Freeze-thaw cycling method	pH sensitivity	[49]
	Chitosan	Freezing method	Thermosensitive; Shortly gelation time (3 min or less)	[50]
	Chitosan/Poly(Vinyl Alcohol)	Dry at room temperature in vacuo	pH-specific release behavior	[51]
	Gellan gum	Gelation at room temperature	Biocompatible material	[52]
	Hydroxypropyl methylcellulose	Dispersion method	Benefit for skin	[53]
	Nanocellulose	30 min with autoclaving (121 ℃, 103 kPa)	Sustained release	[54]
	poly (vinyl alcohol)	Freezing drying method	Long-term release	[55]
	Soy soluble polysaccharide	Reduced pressure and stored in a desiccator	3D-nanocomposites, superabsorbent, malleable, bioadhesive	[56]
	Xanthan	Freezing drying method	Long-term release	[57]
Chemically cross-linked cyclodextrin-containing hydrogels	4-arm-Polyethylene glycol-Succinimidyl Glutarate	Nucleophilic substitution-based method	Improved the therapeutic effect	[58]
	Agarose gel	Nucleophilic substitution-based method	Low gelling temperature for controlled drug delivery	[59]
	Carboxymethyl cellulose	Free radical polymerization crosslinking-based method	pH-responsive behaviour	[60]
	Carboxymethyl cellulose	Nucleophilic substitution-based method	Biocompatible, capable of controlling the release for a long duration	[61]
	Chitosan	Nucleophilic substitution-based method	Local antibiotic release	[62]
	Nanocellulose	Nucleophilic substitution-based method	Cell compatibility, non-cytotoxicity	[63]
	Polyvinyl alcohol	Nucleophilic substitution-based method	Good strength, elasticity, WVP, and swelling ability	[64]
	Poly(N-isopropylacrylamide)	Free radical polymerization crosslinking-based method	Thermoresponsive	[65]
	Poly(2-hydroxyethyl methacrylate)	Nucleophilic substitution-based method	Sustained drug delivery	[66]
	Sodium hyaluronan	Nucleophilic substitution-based method	Controlled release	[67]