Using hydrophilic polysaccharide to modify supramolecular hydrogel from a low-molecular-mass gelator

Small molecular hydrogels hold important potential applications in bioengineering and biomedicine. However, they suffer usually from weak mechanical and water-retention properties. In this work, hydrophilic dextran polysaccharide was used for the first time to modify the properties of the supramolecular hydrogel derived from a low-molecular-mass gelator, 2, 6-di[N-(carboxyethyl carbonyl)amino]pyridine (DAP). When the DAP hydrogel was formed in aqueous dextran solution with a rather low viscosity, we found that it could be significantly reinforced with respect to its viscoelastic moduli, complex viscosity and hydrogel strength. Moreover, the modified DAP hydrogel has a higher bound water content. These property changes could be attributed to the formation of intermolecular hydrogen bonds between DAP and dextran. By relating the dynamic rheological data with a scaling model, it was found that native and modified DAP hydrogels had both a fractal aggregate structure and the incorporation of dextran resulted in an increase of the fractal dimension. Scanning electron microscopy revealed that a more complex network structure was formed in the DAP hydrogel with dextran.