Preparation of a chitosan/carboxymethyl chitosan/AgNPs polyelectrolyte composite physical hydrogel with self-healing ability, antibacterial properties, and good biosafety simultaneously, and its application as a wound dressing

The preparation of hydrogel wound dressing materials with high antibacterial activities and good biosafety simultaneously can be relatively challenging. Aiming at solving this crucial problem, a multi-functional chitosan/ carboxymethyl chitosan/silver nanoparticles (CTS/CMCTS/AgNPs) polyelectrolyte composite physical hydrogel is constructed by in situ photoreduction of silver ions with alpha-hydroxy of CMCTS and semi-dissolution acidification sol-gel transition (SD-A-SGT) methods using natural polymers with no chemical reductant involved. The XRD, TEM and IR characterizations reveal a highly uniform structure of the composite hydrogel with good mechanical strength. The composite hydrogel also exhibits good self-healing ability, and the self-healing mechanism of the composite hydrogel prepared by natural polymers with high similarity is put forward on the basis of molecular dynamics simulation. The AgNPs gives the hydrogel excellent antibacterial activities against both S. aureus and P. aeruginosa., while the preparation method with no chemical reductant and crosslinking agent required endows the hydrogel high biocompatibility. The great application potentials of CTS/CMCTS/AgNPs polyelectrolyte composite hydrogel are demonstrated with its promoting effects on the healing of P. aeruginosa infected wounds as the wound dressing. It is a breakthrough in achieving hydrogels with desired biosafety and antibacterial activities simultaneously. The composite hydrogel is found with great application potentials as wound dressing.