The Preparation, Antibacterial Activity And Antibacterial Mechanism Of Inorganic Antibacterial Compounds

ObjectiveThe purpose of this thesis is to explore an inorganic antibacterial material with satisfactory antibacterial activity.Sol-gel technique was used to prepare nanometer titanium oxide,nanometer iron-doped titanium oxide,nanometer lanthanum—doped titanium dioxide on six levels.The antibacterial activity of 18 samples was evaluated on Staphylococcus aureus(ATCC 6538,SA),Escherichia coli(ATCC 8099,Eco),and Pseudomonas aeruginosa(ATCC 15442,Pae).The antibacterial mechanism,the influential factors,stability and safety of the optimized nanometer antibacterial were researched.Methods1.The nano-TiO₂,nano-Fe-TiO₂ and nano-La-TiO₂ materials were prepared by sol-gel technique on different kinds of temperature(six levels).Scanning electron microscope and energy spectrometer technology were used to characterize these products.2.SA,Eco and Pae were chosen as representative strains.Shake Flask Test was used to evaluate the best antibacterial activity among 18 specimens.Tube Test method was used to determine the minimal inhibitory concentration(MIC)and minimal bactericidal concentration(MBC)of the best antibacterial activity sample (code designation is FH1).3.The antibacterial mechanism of the FH1 was investigated in this chapter.SA, Eco and Pae were chosen as representative strains.Firstly,we compared the differences of antibacterial activity on ultraviolet radiation and those away from light, then discussed the antibacterial mechanism.Secondly,the change of bacterial structure,by the optical microscope and electronmicroscope(EMS),before and after the material's action was observed.Lastly,the changes in sodium dodecyl sulfateate-polyacrylamide gel electrophoresis(SDS-PAGE)of protein of bacterial were observed after exposure to FH1.4.SA and Eco were chosen as representative strains to observed the influencing factors on antibacterial activity of FH1:exposure chamber,affected time,generation of strains,bacterial content,pH value and organic factors et al.5.Firstly,MIC and MBC of this material on SA and Eco on different disposal time were compared.Secondly we surveyed the generated effect of FH1 on successive bacterial.Lastly,sub—inhibitory concentration was used to disinfect SA and Eco 10 generations continuously,the change of toxicity,biochemistry and antibacterial resistance spectra after and before disinfection were compared.Clinical strains XY449 and XY396 disinfected 10 generations continuously,and the changes of the plasmid map were compared.6.The tests of acute skin stimulation on rabbit and acute oral toxicity on mice were conducted to evaluate the safety of the nanometer antibacterial compounds. Micronucleus occurrence of bone marrow cells on mice was used to explore the genetic toxicity of the nanometer antibacterial compound.Results1.The nanometer materials,without any foreign materials,got from sol-gel technique,has been confirmed by the scanning electron microscope and energy spectrometer technology.2.Samples1,2,10,12,18 have not any antibacterial activity on 3 strains,and others have antibacterial activity on 3 strains in different degrees.Number 13 (nanometer lanthanum—doped titanium dioxide,FH1)has the best antibacterial activity.The MIC of SA,Eco or Pae was 12.5,25,25mg/ml;and the MBC was 25,50, 50mg/ml respectively.3.Besides of the photochemical catalysis yet presents rare element metal (REM)contact and ion extruder antibacterial mechanism.Optical and transmission electron-microscope observation confirmed that the surface and ultra-microstructure of the SA,Eco and Pae were all changed after exposed to FH1.SDS-PAGE map disclosed the change of tropina after antibacterial process.4.The antibacterial activity of FH1 can not be affected by the illumination condition.The long time acts,the better the antibacterial effect shows.Concentration of the compounds should be increased if clonal formation unit of the bacterial increased.Modified of initial pH between 5.0 and 9.0 does not affect the inactivation rate.The existed of organism resulted in a significantly weaken disinfection action of FH1.5.There is no difference of MIC and MBC on SA and Eco and on different disposed time.On inhibitory concentration,after added SA for successive 6 times, Eco for successive 5 times,the antibacterial activity decreased obviously.After 10 generations continuous disinfection,there was no change in the toxicity,and antibacterial resistance spectra of SA and Eco,but the biochemistry has minor change in SA and Eco.The plasmid map has not obviously changes on XY396 and XY449.6.The stimulating score on the rabbit skin is zero in integrated skin,0.5 in damaged skin respectively when the concentration was used as 5×MIC and confirmed this material belongs to nonirritant material.Mice were safety when the oral dose of this material is 5000mg/kg and confirmed is a practical innocuous material.On day 0,7 and 14,the occurrence of micronucleus of bone marrow cells was obviously lower than that of the control group,and similar to the blank group.Conclusion1.The inorganic materials got from Sol-Gel technology are all nanometer compounds and do not contented any foreign substance.2.Among these 18 samples,sample 1,2,10,12 and 18 have not antibacterial activity on SA,Eco and Pae.Sample 13(nanometer lanthanum-doped titanium dioxide, code name FH1)has the extreme strong antibacterial activity.3.The antibacterial activity of FH1 can not be affected by the illumination condition.The antibacterial activity can be affected by the time duration,bacterial concentration,bacterial generation,pH value and the existing of organisms.The compound has good stability.It belongs to nonirritant and practical innocuous material.Does not impacted the micronucleus rates on mice' bone marrow cell.4.Besides of the photochemical catalysis,FH1 presents rare earth metal contact and rare earth ion extruder antibacterial mechanisms.The appearance, ultra-microstructure and tropina are all changed after the antibacterial process.