RESUMO
PURPOSE: Since wounds are a primary source of infection, it is desirable to have a wound dressing that prevents infectious processes during the tissue regeneration phase. In this regard, silver nanoparticles, oregano essential oil, and chitosan have been utilized due to their antimicrobial activity. This work focused on the preparation of a composite containing these three components, intended to provide protection for wounds, especially by exerting antimicrobial effects. METHODS: A composite based on chitosan nanoparticles loaded with oregano essential oil (OEO) and silver nanoparticles was fabricated through the casting-solvent evaporation method. The films were prepared from a suspension of chitosan nanoparticles. The nanoparticles were characterized by size and entrapment efficiency. The surface of the films was observed by SEM, and the mechanical resistance, occlusive capacity, and antimicrobial activity against S. aureus, E. coli, and P. aeruginosa were evaluated. The release of OEO from the films was studied using Franz-type cells. RESULTS: A composite was successfully prepared from a dispersion of OEO-loaded chitosan nanoparticles (147.8 nm, PDI = 0.35; entrapment efficiency = 80.9 %; loading capacity = 38 %) and silver nanoparticles (19.6 nm, PDI = 0.4). A film could be formed that made the composite by pouring the chitosan nanoparticle dispersion directly into molds. The composite presented advantageous characteristics, such as being semi-occlusive (occlusion factor ~ 40 % and reduction in TEWL of 18 %), allowing the sustained release of OEO (about 0.2 mgCm-2 h-1 during 8 h), and having antimicrobial activity for the three strains evaluated. CONCLUSION: The prepared composite can be considered a potential candidate for dressing materials intended to prevent and treat wound infections.
RESUMO
Sodium alendronate is a nitrogen-containing bisphosphonate, widely used for osteoporosis treatment. However, due to its several oral administration drawbacks, the transdermal route represents an interesting option. The aim of this study was to formulate sodium alendronate in two submicron delivery systems, microemulsions, and solid-in-oil nanosuspensions, both systems possessing permeation enhancing properties. The composition of microemulsions was determined through the construction of pseudo-ternary phase diagrams. Solid-in-oil nanosuspensions were prepared by an emulsification-freeze-drying method, evaluating the effect of sonication time and the type of surfactant. According to the results of drug loading capacity, droplet/particle size, and polydispersity index, two microemulsions and two nanosuspensions were selected to perform the subsequent evaluations. The results showed that microemulsions allowed a faster release of alendronate than nanosuspensions. The permeation capacity of alendronate formulations was assessed through the synthetic membrane Strat M®, as well as through pigskin, finding higher fluxes with microemulsions than with nanosuspensions. In order to elucidate the effect of the formulations on the permeability barrier of the stratum corneum, techniques such as ATR-FTIR and TEWL were used. Finally, measurements of erythema intensity showed that neither of the two nanosystems caused skin irritation after 2 h of contact. The results suggest that alendronate formulated in a microemulsion can be a viable transdermal nanocarrier for osteoporosis treatment.