Silk fibroin nanofibers containing chondroitin sulfate and silver sulfadiazine for wound healing treatment

Abstract

Nanofibers containing silk fibroin (SF), chondroitin sulfate (CS) and silver sulfadiazine (SSD) were made up through electrospinning technique, to produce new dressings with the potential to control the wound infections. Poly (ethylene oxide) (PEO) was added to the acidic water solution used for electrospinning to improve electrospinnability. Fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR-ATR), energy dispersive X-ray Spectroscopy (EDS), Differential Scanning Calorimetry (DSC), flame atomic absorption spectrocopy (FAAS) and biological analysis. The nanofibers average diameter was between 262 and 328 nm before PEO removal and between 242 and 345 nm after PEO removal. The FTIR-ATR and DSC results showed that PEO was removed from the surface of the nanofibers by washing the as-electrospun fibers with absolute ethanol. FTIR-ATR and EDS results showed that CS and SSD remained in the nanofibers. The quantification of Ag+ ions on the nanofiber surface showed that CS had a major influence on the remaining SSD content of the nanofibers, which was between 75 and 100%. Biological assays showed that the as-obtained nanofibers are not toxic to healthy Vero cells with values between 98 and 100% of cell viability. Antibacterial activity tests showed that the concentration of CS significantly influenced the antibacterial activity of the samples. In vivo experiments with Wistar rats revealed that SF nanofibers containing CS and SSD had similar results to standard SSD cream treatment, with the advantage of being applied only once to the patient, avoiding discomfort and pain in dressing changes. CS played an important role as a stabilizing agent of electrospinning solutions improving SSD-remaining and enhancing the antibacterial activity of nanofibers against bacteria through in vitro.