Investigation Of Antibacterial Activity,Mechanism And Application Of Titanium Dioxide And Its Complex Nanomaterials

Once the pathogens meet the suitable conditions it will grow exponentially.How to deal with the threat of pathogens in the face of humans is the investigative hotspot,it is an efficient path for control the spread of pathogen source and reduce the disease outbreak.Pathogens enter the circulation of the blood,produce toxins and other metabolites,endanger human life and health,and cause millions of people died due to bacterial infection.Due to the antibiotic abuses,infection problems of multi-drug resistant bacteria have emerge in endlessly;conventional antimicrobials,always have the disadvantages of poor heat resistance,easy decomposition,volatile and poor security,which are unable to meet the increasingly serious problem of bacterial infection outbreak and make human be at a loss what to do.Because of the special physical and chemical properties due to the increase of the surface area and the damage of the crystal lattice,the nano antibacterial agents can get unexpected results,for its durability,heat resistance,biocompatibility and difficult to produce drug resistance,it has been widely recognized and studied by the scientific research field.The nano antibacterial mechanism mainly consist:(1)combining with the genetic material in bacteria,inhibit the synthesis of DNA,RNA and protein,make the bacterial inactivation;(2)interact with the bacterial cell membrane and catalyze the cleavage of bacterial cell membrane,which leads to the death of bacteria;(3)combined with the chemical groups in bacteria,make the loss of protease activity and leads to the death of bacteria.This paper consists of three chapters:Chapter 1: Introduction,we mainly introduce the effects of bacterial diseases on human health,the common treatment methods and limitations of bacterial infection,the research progress and future prospect of nano-medicine in bacterial infection.Finally,the application of titanium dioxide nanomaterials in antibacterial specialty is introduced.Chapter 2: The graphene oxide-chitosan(GO@CS)thin film was synthesised by a self-assembly method and loaded the titanium dioxide nanoparticles on the surface of this thin film by in situ reduction method(the ratios of GO:CS:TiO2 are 1:20:2,1 : 20 : 4,1 : 20 : 8,respectively).Study the inhibition against the growth of Aspergillus niger(A.niger)and Bacillus subtilis(B.subtilis)in different TiO2 content in GO:CS:TiO2.Size and distribution analysis of TiO2 on GO:CS:TiO2 film through TEM graph;the antibacterial properties of GO:CS:TiO2 against A.niger and B.subtilis were performed by colony growth plate method,conductivity method and coomassie brilliant blue method,laser scanning confocal microscope and scanning electron microscope experiments.The changes of polyphenol oxidase and superoxide dismutase in fruits were measured,plant tissue culture and animal cell biocompatibility test,which showed that GO:CS:TiO2 has excellent biocompatibility.When the ratio of GO:CS:TiO2 is 1:20:4,the best antibacterial properties and biocompatibility are simultaneously obtained.We believe that these findings reveal a great potential for the application of GO:CS:TiO2 antibacterial materials.Chapter 3: As the representative of the pathogenic bacteria,Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)are poses a huge threat to human health and economic environment.In order to control the spread and reduce the harmful of these pathogens,it is very important to control the proliferation of pathogenic bacteria from its source.For this purpose,we have synthesized a titanium dioxide-vanadium pentoxide(TiO2@V2O5)nano antibacterial agent by a simple method.It can effectively improve the performance of photosensitive of TiO2 Through the modification and after the interaction with bacterial biofilm can produce reactive oxygen to make the bacterial biofilm damaged,and thus play a bacteriostatic effect.In this research,we show that TiO2@V2O5 is a kind of spherical nanoparticles with uniform dispersion and stability,and it can produce photocurrent under illumination;using the disk diffusion method to measure the OD value of bacteria and it shows that TiO2@V2O5 can exhibit excellent antibacterial properties under illumination,which had revealed that the relationship between the antibacterial properties and the photosensitive properties of TiO2@V2O5;the study of a series of antibacterial mechanisms revealed that TiO2@V2O5 could produce reactive oxygen species mainly by hydroxyl radical,which was the main reason for TiO2@V2O5 to produce antibacterial activity;finally,the experiments of animal or plant compatibility showed that TiO2@V2O5 had no harm to the environment and proved to be of great potential in the future.