Title : Antimicrobial electrospun nanofibers for wound dressings
Wound dressing technology is of major interest in the actuality in order to avoid undesired effects when burns or skin wounds are treated, especially their risk for microbial contamination and subsequent infection. Hence, silver nanoparticles had claimed importance as an antimicrobial agent and their use have been increased in the biomedical field. For these reasons, a comparative study of different methods to synthesize electrospun polymeric fibers loaded with silver nanoparticles (PCL/PVP-AgNPs) was investigated and performed, such as direct blending, ultraviolet irradiation, thermal treatment, and silver mirror reaction methods, the time when the silver nanoparticle's precursor was added was also taken in consideration and its antimicrobial efficiency is reported as well. The morphology, structure, and size of the fibers were obtained using the scanning electron microscope (SEM) where the loading of the AgNPs in the fibers and its distribution was demonstrated. Fourier transform infrared spectroscopy and Raman spectroscopy was used to measure the physicochemical properties of the fibers. The dynamic light scattering study made it possible to measure the size of the nanoparticles and the surface charge of the samples. The antimicrobial study was carried out for 24, 48, and 72 h in Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. Cytotoxicity was evaluated with the MTT assay using HFF-1 human fibroblast cells. The results showed that the method with the best antimicrobial effect in both bacteria is the one where a reduction by ultraviolet light irradiation was performed to load the AgNPs and the AgNPs precursor was added before the electrospinning process. In SEM micrographies, the best distribution of AgNPs on the fiber was observed in the silver mirror reaction method, but the UV radiation method promotes this distribution efficiency, the physicochemical properties obtained were desirable, the particle size falls within the range to be considered nanoparticle (~17 nm). These results determined the best method to prepare antibacterial wound dressings.