Chitosan derivative-based mussel-inspired hydrogels used as dressings for infectious wound healing

Abstract

An ideal and highly desired wound dressing for the repair of infectious wounds should provide a moist environment, close adhesion to the wound site, and self-healing and antibacterial properties. Thus, in the present study, we manufactured multifunctional, mussel-inspired hydrogels CACS-Fe3+-CYCS and CACS-Fe3+ using catechol-grafted-chitosan (CACS) and cysteine-modified-chitosan (CYCS) as raw materials and ferric chloride as a cross-linking agent. The CACS-Fe3+-CYCS hydrogel exhibited excellent adhesion because of metal coordination between the ferric ion (Fe3+) and catechol groups and a strong covalent bond between the catechol groups and the amino and sulfhydryl groups. Its self-healing quality was attributed to the dynamic and reversible properties of metal coordination. The loading of the total flavones of Resina Draconis (RDF) provided the hydrogel with good antibacterial properties. The antibacterial rates of the CACS-Fe3+-CYCS and RDF-CACS-Fe3+-CYCS hydrogels for Escherichia coli and Staphylococcus aureus were 90.62% and 96.45% and 99.98% and 100.00%, respectively. The RDF-CACS-Fe3+-CYCS hydrogel at pH 5.0, 6.8, and 8.0 in phosphate-buffered saline exhibited slow, sustained cumulative release rates of 53.94%, 71.97%, and 85.13% at 60 h, respectively. Complete wound healing was observed by day 12 in the CACS-Fe3+-CYCS hydrogel group (healing ratio = 96.59%). In the RDF-CACS-Fe3+-CYCS hydrogel group, complete healing was achieved by day 9 (healing rate = 94.46%; highest value at all treatment times). Thus, both hydrogels can be used as an ideal dressing for treating infectious wounds. The combination of traditional Chinese medicine and novel wound dressings can work synergistically, providing a novel strategy for designing biomimetic hydrogels for potential applications in wound healing.