RESUMO
Silica-coated, silicon nanotubes (SCSNTs) and silica-coated, silicon nanoparticles (SCSNPs) have been synthesized by catalyst-free single-step gas phase condensation using the arc plasma process. Transmission electron microscopy and scanning tunneling microscopy showed that SCSNTs exhibited a wall thickness of less than 1 nm, with an average diameter of 14 nm and a length of several 100 nm. Both nano-structures had a high specific surface area. The present study has demonstrated cheaper, resistance-free and effective antibacterial activity in silica-coated silicon nano-structures, each for two Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) was estimated, using the optical densitometric technique, and by determining colony-forming units. The MIC was found to range in the order of micrograms, which is comparable to the reported MIC of metal oxides for these bacteria. SCSNTs were found to be more effective in limiting the growth of multidrug-resistant Staphylococcus aureus over SCSNPs at 10 µg/ml (IC 50 = 100 µg/ml).
Assuntos
Anti-Infecciosos/administração & dosagem , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/fisiologia , Nanopartículas/administração & dosagem , Dióxido de Silício/administração & dosagem , Silício/administração & dosagem , Anti-Infecciosos/síntese química , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/administração & dosagem , Materiais Revestidos Biocompatíveis/síntese química , Relação Dose-Resposta a Droga , Gases/química , Teste de Materiais , Staphylococcus aureus Resistente à Meticilina/citologia , Nanopartículas/química , Transição de Fase , Silício/química , Dióxido de Silício/químicaRESUMO
We report on the characteristics of a new class of Si-based nanotubes and spherical nanoparticles synthesized by the dc-arc plasma method in a mixture of argon and hydrogen. These two nanostructures share common properties: they are hollow and possess very thin, highly polycrystalline and mainly oxidized walls. In particular, we get several hints indicating that their walls could constitute only one single Si oxidized layer. Moreover, we find that only the less oxidized nanotubes exhibit locally atomic ordered, snakeskin-like areas which possess a hexagonal arrangement which can be interpreted either as an sp(2) or sp(3) hybridized Si or Si-H layer. Their ability to not react with oxygen seems to suggest the presence of sp(2) configuration or the formation of silicon-hydrogen bonding.
