Photodynamic chitosan sponges with dual instant and enduring bactericidal potency for treating skin abscesses

Abstract

The emergence of multidrug-resistant (MDR) bacteria has made wound infection treatment difficult, calling for novel strategies for effective elimination of bacteria in wounds and promoting their recovery. Herein, we report a novel chitosan antibacterial sponge combining zinc oxide particles (ZnO) and the photosensitizer chlorin e6 (Ce6), named CS-ZnO/Ce6 sponge for combating multidrug-resistant bacteria and treating skin abscesses. The fabricated CS-ZnO/Ce6 sponge had porous structure with high porosity, conducive to absorbing the wound exudate. Meanwhile, the hemostatic property of this sponge enabled it to stop the continuous bleeding of the wound. Upon 660 nm light irradiation, the CS-ZnO/Ce6 sponge exhibited an instant photodynamic bactericidal effect against several typical MDR strains, and the presence of ZnO could continuously inhibit bacterial growth. In addition, local remedy of methicillin-resistant Staphylococcus aureus (MRSA)-infected mice with CS-ZnO/Ce6 sponge with light irradiation caused a potent immediate bacterial killing effect and prolonged bacteriostasis in mice with skin abscesses, leading to the rapid recovery of the wound. The biocompatibility of the CS-ZnO/Ce6 sponge in mice was also verified by histological examination of the main organs. Collectively, the CS-ZnO/Ce6 sponge with broad-spectrum antibacterial activity and long-term bacterial inhibition potential could be useful for treating microbial infections and accelerating wound healing.

Keywords: Chitosan; Drug-resistant bacteria; Photodynamic antibacterial therapy; Wound dressing; Zinc oxide.