CONICET | Buscador de Institutos y Recursos Humanos

Silica core-shell nanoparticles and collagen type I nanocomposite hydrogels are evaluated as medicated dressings. It is known that collagen is a key component of a healing wound. However, due to the large porosity of the scaffold compared to drug dimensions, the kinetics of release is usually too fast. In this sense, the use of nanocomposite materials where the drugs are associated with nanoparticles embedded in the scaffold has attracted increasing attention. In the present work, 300 nm silica core?shell particles (0.5 M SiO2), having the capability to simultaneously deliver two topical antibiotics, gentamicin sulphate and sodium rifamycin, are combined with concentrated collagen type I (5 mg mL-1) and evaluated as dressings to prevent infection in chronic wounds. By scanning electron microscopy (SEM) imaging, a dense fibrillar collagen network with its typical periodic banding pattern and an homogenous particle distribution were observed. A sustained antibacterial effect was ovserved for over 10 days when the nanocomposites were evaluated in vitro assays using Staphylococcus aureus for the antibiograms. In all cases, double loaded nanocomposite (gentamicin and rifamycin) showed greater activity than those only loaded with gentamicin, being indicative that both drugs are released during the experiment term. An unloaded composite showed no antibacterial activity. In vivo biocompatibility studies in subdermal implants and antibacterial efficiency were performed in male Wistar rats. A significant difference was found between the double loaded and unloaded (control) composite effect in the treatment on staphylococcal infection, the loaded composite lowered the number of bacteria in around two and a half colony forming unit (CFU) per cm2 rat skin.