Table 2. Comparison of small molecule release behaviour of pH-responsive hydrogels.

No.	Polymer composition	Drug loaded	pH of release buffer medium	Release time (H)	% Release
1	PLGA polymeric nanoparticles78	Mometasone furoate	Cryoprotection in sucrose pH 6.4	180	87
			Cryoprotection in sucrose pH 7.4		55
			Cryoprotection in mannitol pH 6.4		70
			Cryoprotection in mannitol pH 7.4		60
2	GG-GA-La-GO79	Amoxicillin trihydrate	pH 7.4	6.5	60
3	DOX-CaCO3-alginate80	Doxorubicin	pH 4.5	48	56
			pH 6.5		30
			pH 7.4		6
4	Cs/HA/Fe3O4 (ref. 39)	Ciprofloxacin	pH 7.4	13	Nearly 100
			pH 8
			pH 5
			pH 2
5	Su-CNC/PNIPAm5	Famotidine	pH 2	2	100
			pH 10	8	100
6	CA-DA/OP6 (ref. 81)	Doxorubicin	pH 5.7	60	87
			pH 6.8		75
			pH 7.4		52
7	Chito/HA82	Ciprofloxacin	pH 5.5	6	78.8
			pH 7.4		86.1
		Curcumin	pH 5.5		48.7
			pH 7.4		89.9
8	CP-g-AMPS83	Ellagic acid		48
	KAE-6		pH 1.2		92.13
			pH 7.4		77.28
	KAE-3		pH 1.2		57.03
			pH 7.4		46
9	H1 PAM84	Dependal-M	pH 5.8	1.5	16.8
	H1 PAM				16.4
10	PAcVSAa	Sulfadiazine	pH 5	48	82.12
			pH 7.4		32.35
			pH 8		24
		TBS	pH 5		80.67
			pH 7.4		26
			pH 8		24.09

^aCurrent work.