Facile fabrication of redox/pH dual stimuli responsive cellulose hydrogel

A cellulose-based multi-responsive hydrogel was prepared by the facile incorporation of enamine and disulfide bonds in the same system at physiological pH. The cellulose hydrogel was obtained by simply mixing aqueous solutions of cellulose acetoacetate (CAA) and cystamine dihydrochloride (CYS) at room temperature. The internal morphology, structure, and mechanical properties of the cellulose hydrogel were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and Raman spectroscopies, nuclear magnetic resonance (NMR), and water retention, porosity, and rheology measurements. The cellulose hydrogel showed reversible sol-gel transitions in response to both pH and redox triggers. In addition, it displayed good stability under physiological conditions. Gels loaded with small molecules showed variable release properties in response to pH or redox stimuli. The preparation protocol presented here could be used to fabricate other multi-responsive polysaccharide hydrogels.