Strong and tough collagen/cellulose nanofibril composite films via the synergistic effect of hydrogen and metal–ligand bonds

In this paper, the collagen (COL)/cellulose nanofibril (CNF) composite films were fabricated via solution casting-solvent evaporation induced COL molecule self-assembly in CNF supramolecular network to form a high-density physically crosslinked supramolecular double network and then moved to inorganic saline solutions to induce the structure rearrangement and crosslinking of the composite films on the nanoscale through soaking. The supramolecular double network structure and synergistic effect of hydrogen and metal–ligand bonds on the mechanical properties of the COL/CNF composite films were also investigated through various characterization techniques to thoroughly comprehend the reinforcement mechanism. COL/CNF composite films with ferric ion exhibited excellent thermal stability, outstanding dry and wet mechanical performances (112.7 MPa and 55.5 MPa). Additionally, the composite films displayed super bioactivity and antimicrobial activity even in the presence of metal ions, making them promising materials for tissue engineering and regenerative medicine.