The Research Of Activities Of Nano-sized Material And Its Bacteriostasis Mechanism

Several nano-sized titanium dioxides (TiO₂) of different calcination temperatures and reaction times had been made and exosyndromed to do the further researches of activities of nano- TiO₂. The result indicated: when the calcination temperature raised from 400 ℃ to 850 ℃, nano TiO₂ were all anatase and the degradation rate to methyl orange also raised which had a highest level at 850℃. When the calcination temperature raised from 850℃ to 1100℃, rutile began to appear and its rate raised gradually which arrived at 100% at 1100 ℃. While the rate of rutile raised, the degradation rate to methyl orange reduced.Paper disk method, cup-plate method and directly piled-up method were used to do a preliminary screening to bioactivities of the different nano materials in order to find the best method of preliminary screening. Meanwhile, several typical microbes that had different characteristics were chosen to determine the antibioterial spectrum of nano TiO₂. The material which had the best bioactivity in the preliminary screening (aclcination temperature: 850℃, time: 1.5h) was chosen to do the further research. The tested microbes were incubated together with the TiO₂ under different lights to investigate their effects to TiO₂. The minimal inhibitory concentration (MIC) and the maximal inhibitory concentration were determined to find the relationship of the concentration of TiO₂ and its bioactivity. The results indicated the directly piled-up method which gained a big and clear inhibition zone was the best way to do the bioactivity screening of the same material as TiO₂. Nano TiO₂ had a wide antibacterial spectrum including bacterium, actinomycetes, fungus, yeast and so on. There was no visible specificity of its bacteriostasis. Exposed in the different lights, nano TiO₂ could be catalyzed by the lights with the vicinal 365nm lightwaves to show the good bacteriostasis. Considering the synthetic factors, the fluorescent lamp was the best illuminant. The inactivity concentration range in which TiO₂ represented the bacteriostasis was 0.1mg/ml-1.0mg/ml. The effect of bacteriostasis would not go on raising when the concentration of TiO₂ was more...