A physical crosslinked pH-sensitive hydrogel based on hemicellulose/graphene oxide for controlled oral drug delivery.

The design of innovative pH-sensitive hydrogels for oral drug delivery is particularly promising for the treatment of intestinal diseases. The traditional pH-responsive hydrogels still have some problems such as low biocompatibility, complex preparation process and poor therapeutic effect, so a new method needs to be developed to solve these problems. Here, a pH-sensitive hemicellulose/graphene oxide (HC/GO) composite hydrogel (HGCH) was prepared through a one-step strategy. Benefitting from the multiple hydrogen bonding between HC and GO, HGCH possessed a low gelator concentration (∼0.79 wt%), well-defined 3D porous network and excellent mechanical properties. Remarkably, HGCH exhibited pH-induced gel-sol transition and a high drug loading efficiency, showing great potential as a candidate for advanced drug carrier. The drug loading and release test revealed that about 85 % Vitamin B 12 was released in neutral PBS solution (pH 7.4). However, only about 30 % drug was diffused into acid medium (pH 1.7) in the same period, which suggested the HGCH have high adaptability to soluble drugs and pH sensitivity triggered release. Further cellular toxicity tests demonstrated that the HGCH was nontoxic and biocompatible for cells. Thus, the physically cross-linked HGCH would be an attractive drug carrier for controlled drug release at physiological pH in the future.