Co-delivery of doxorubicin and curcumin by a pH-sensitive, injectable, and in situ hydrogel composed of chitosan, graphene, and cellulose nanowhisker

[Display omitted] •A hydrogel composed of chitosan, graphene, and cellulose nanowhisker was synthesized.•The hydrogel was pH-sensitive and injectable.•The hydrogel showed a pH-sensitive release of doxorubicin and curcumin. Hydrogels are promising carriers for the controlled drug delivery in response to the external stimuli such as pH and temperature. Here, a new hydrogel is designed and synthesized from the cross-linking of graphene, chitosan, and cellulose nanowhisker via Schiff base reaction by a synthetic dialdehyde. The hydrogel presented a flexible structure and responded to altering pH and adding the external stimuli such as benzaldehyde and amino acid cysteine. The synthesized hydrogel was stable under physiological conditions. In vivo test showed that the hydrogel is subcutaneously injectable. Three drug-loaded hydrogels were synthesized, and in vitro drug release study showed a pH-dependent release of drugs in PBS solution.