Supramolecular self-assembly of an herbal fructan and chitosan hydrogel: analysis of the fructan, gel structures and the molecular interaction mechanisms

Polysaccharide-based supramolecular self-assembled hydrogels are promising biomaterials owing to their biocompatibility and dynamic controllability. This study was to explore the use of a polysaccharide (PSP) isolated from a well-known Chinese herb, Polygonatum sibiricum Red. (Huangjing) in the supramolecular self-assembled hydrogel. PSP was characterized as a neutral fructan with a backbone of →1)-β-D-Fru f -(2 → and →1,6)-β-D-Fru f -(2 → units bearing O-6–substituted branches. PSP/Chitosan (PSP/CS) hydrogels were prepared with different PSP concentrations (4, 6, 8, 10, 12 wt%), forming 3D network porous structure composed of nanofiber chains, with the pore size ranging from 0.67 to 13.67 μm. Increasing PSP content markedly enhanced gel strength and stability, as evidenced by higher storage modulus (G'), increased compressive modulus (0.03–0.75 kPa), and improved thermal stability (maximum degradation-rate temperature from 290 to 302 °C). In addition, PSP/CS hydrogels exhibited high swelling (2673 ± 65%) and water retention (78.26 ± 1.58%) properties. Hydrogen bonding was the predominant driving force for self-assembly. Furthermore, PSP/CS hydrogel preliminarily showed good cytocompatibility toward Caco-2 cells. In conclusion, these findings clarify the structure–assembly–property relationships of PSP/CS hydrogel and suggest a design strategy for exploiting fructan polysaccharides in advanced biomaterials.