Table 2.

pH-sensitive hydrogels and drug delivery system.

Hydrogel	Drug	Cell line (in vitro)	Cancer (in vivo)	Characteristics and applications	References
Acrylic Acid and PEGDA	Salicylic Acid (SA)	3t3 fibroblast cells	–	Sa based pH sensitive hydrogel reveals good pH sensibility and great biocompatibility	Demirdirek and Uhrich, 2017
CS and GP	DOX	Mcf-7 cells (breast cancer)	Breast cancer	With an LCST of 39°C, the gel reveals DOX when pH = 5.5	Fathi et al., 2019
Chitosan Dihydrocaffeic Acid (CS-DA) and Oxidized Pullulan (OP)	DOX and Amoxicillin	Hct116 cells (colon tumor cells) and e. Coli	Colon tumor and infection	DOX and amoxicillin co-loaded hydrogel response to pH decrease. The hydrogel is an ideal system for mucosa-localized tumor and infection management	Liang et al., 2019
GC-PF127	DOX	H22 (breast cancer)	Breast cancer	Response to small pH change, hydrogel release DOX-loaded micelles with tumor-targeted	Liu et al., 2017
CEC-PEGDA	DOX	Hepg2 (liver cancer) and l929	Liver carcinoma	Good cytocompatibility and anti-tumor effect. The pH-responsive hydrogel is a promising delivery system for liver cancer treatment	Qu et al., 2017
PEGMA and AAC	5-FU	Hepg2 (liver cancer) and LO2	Liver carcinoma	Controlled and targeted drug delivery for liver carcinoma	Yue et al., 2019
CS/HA/GP	DOX	Hela (cervical cancer)	Cervical cancer	Good pH sensitivity for the localized management of cervical cancer	Zhang et al., 2018