Síntese, caracterização e atividade antimicrobiana de nanopartículas de céria suportadas em fibras submicrométricas de sílica e de dióxido de titânio.

Abstract

The purpose of this work was the production of submicrometric fibers of silica and titanium dioxide containing ceria nanoparticles for application as an antifungal agent. The fibers of both matrices were make for solution blow spinning (SBS) and submitted to different programming heat treatments. After preparation, the fibers were characterized by thermogravimetry (TG), differential thermal analysis (DTA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Analyses were carried out to evaluate the fibers antimicrobial activity, by the diffusion disc test and the biofilm assay, using C. albicans, C. glabrata and C. krusei fungi. Results of TG and DTA indicated that there were possibly thermal events related to the formation of silanol groups for the SiO2 matrix fibers and the anatase phase for the TiO2 fibers. In the fibers wherein cerium chloride was added, thermal events related to CeO2 formation were identified. By X-ray diffraction it was possible to verify the presence of silica in the amorphous phase and the anatase crystalline phase in the SiO2 and TiO2 matrix fibers, respectively. For the SiO2 fibers, in which there was addition of ceria, only CeO2 crystalline phase was detected. For the TiO2 fibers incorporated with 10 vol% ceria, anatase and CeO2 crystalline phases were detected, whereas the fibers incorporated with 20 and 30 vol% were amorphous. Only the CeO2 crystalline phase was identified for the TiO2 fibers incorporated with 50 vol% ceria. All the fibers obtained fibers with particles in nanoscale scale. The TiO2 matrix fibers presented diameters in submicron and nanometric scale, exhibiting mean diameter in the range between 99 and 345 nm. While SiO2 fibers presented submicron diameters, exhibiting mean diameter in the range between 391 and 657 nm. Among the submicron SiO2 matrix fibers, only the fibers with 50 vol% of CeO2 showed antimicrobial activity against C. albicans fungus. For the TiO2 matrix fibers, the best antimicrobial behavior was obtained for fibers with 50 vol% CeO2, calcined at 600 °C, against C. glabrata fungus.