Development of antibacterial materials for therapy of chronic wounds using composite fibers of polycaprolactone loaded with ZnO nanoparticles with immobilized chlorhexidine on the surface

Introduction. Chronic wounds are a serious public health problem. Infection by antibiotic-resistant pathogens poses the primary risk. In this study, an antibacterial dressing material was made from electroformed polycaprolactone (PCL) fibers that had zinc oxide nanoparticles (ZnO NPs) and chlorhexidine (CHG) attached to their surface.

Materials and methods. The series of dressings were obtained by electrospinning with the incorporation of ZnO NPs at different concentrations (1, 3, and 5%), followed by the immobilization of CHG on the surface. To increase the antipathogen activity, the samples were plasma-treated in a mixture of CO2/C2H4/Ar gas following CHG immobilization by carbodiimide chemistry. We analyzed the structure and chemical composition of the obtained materials using SEM, EDX, XPS, and FTIR spectroscopy. We evaluated the antipathogenic activity against several bacterial and fungal strains. We evaluated the biocompatibility of the samples with a human fibroblast cell line.

Results. The size of the produced ZnO NPs varies between 9 and 13 nm. The composite fibers have a size that varies between 100 nm and 500 nm. EDS analysis confirms that the main components of the fibers are carbon, oxygen, and zinc. The atomic concentration increases to 1.1%, 2.7%, and 3.9%, respectively, as the introduced wt% of ZnO increases. FTIR spectroscopy and XPS analysis confirmed the successful introduction of the ZnO NPs and the subsequent addition of CHG. Measurement of the wetting edge angles of the composite fibers reveals that the material's surface is hydrophilic. Further PCL modification with carboxyl groups and CHG leads to an improvement in the material's wettability. The results of the biological tests confirm that the developed dressings have promising bactericidal and proliferative activity.

Conclusions. We have created a series of new modified composite fiber materials with high potential for wound healing. This research was funded by the Russian Science Foundation (№24-79-10121).