Table 1.

Chemical modification of HA hydrogel [50].

HA hydrogel group modifications	Reaction type	Reagents
-COOH	Amidation	carbodiimides
		2-chloro-1-methylpyridinium iodide
		2-chloro-dimethoxy-1,3,5-triazine
		1,1′-carbonyldiimidazole
	Ugi condensation
	Esterification	alkyl halides
		diazomethane
		tosylate
		epoxides
-OH	Ether formation	epoxides
		divinyl sulfone
		ethylene sulfide
	Hemiacetal formation	glutaraldehyde
	Esterification	methacrylic anhydride
		acyl-chloride activated carboxylate
		alkyl succinic anhydrides
	Carbamate formation	cyanogen bromide
	Oxidation	epoxides
-NHCOCH3	Deacetylation/amidation	hydrazine sulfate