Fabrication of Cu2+-loaded phase-transited lysozyme nanofilm on bacterial cellulose: Antibacterial, anti-inflammatory, and pro-angiogenesis for bacteria-infected wound healing

Bacterial overgrowth in injured wounds causes wound infection and excessive inflammation, leading to delayed wound healing. Successful treatment of delayed infected wound healing demands dressings, which can inhibit bacterial growth and inflammation and simultaneously induce vascularization, collagen deposition, and re-epithelialization of wounds. In this study, bacterial cellulose (BC) deposited with Cu2+-loaded phase-transited lysozyme (PTL) nanofilm (BC/PTL/Cu) was prepared for healing infected wounds. The results confirm that PTL were successfully self-assembled on BC matrix, and Cu2+ were loaded into PTL through electrostatic coordination. The tensile strength and the elongation at break of the membranes were not significantly changed after modification with PTL and Cu2+. Compared with BC, the surface roughness of BC/PTL/Cu significantly increased while the hydrophilicity decreased. Moreover, BC/PTL/Cu displayed slower release rate of Cu2+ compared with BC directly loaded with Cu2+. BC/PTL/Cu exhibited good antibacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa. By controlling copper concentration, BC/PTL/Cu were not cytotoxic to mouse fibroblast cell line L929. In vivo, BC/PTL/Cu accelerated wound healing and promoted re-epithelialization, collagen deposition, and angiogenesis while inhibiting inflammation of the infected full-thickness skin wounds of rats. Collectively, these results demonstrate that BC/PTL/Cu composites are promising dressings for healing infected wounds.