Enhanced mechanical properties of hydroxybutyl chitosan hydrogel through anchoring interface effects of diatom biosilica

The temperature-sensitive hydrogel (H/D) composed of hydroxybutyl chitosan (HBC) and diatom biosilica (DB) was prepared by physically mixing HBC solution with DB at low temperature. The rheological measurements confirmed that the incorporation of DB to hydroxybutyl chitosan could significantly enhance the mechanical strength of the hydrogels without disrupting its reversible phase transition behavior. The hierarchical porous structure of DB and its rich negatively charged surface provided penetration anchor points for HBC molecular chains, which significantly enhanced the mechanical properties of H/D. The gelation temperature, gelation time and mechanical strength could be easily regulated by change of the ratio of DB in composite hydrogel. The maximum storage modulus of HBC hydrogel was increased to 17 times after adding DB. H/D exhibited favorable blood compatibility (hemolysis rate < 5 %) and no cytotoxicity to L929 cells which are promising for the applications as tissue regeneration materials and wound dressing in biomedical fields.