Preparation Of Nano-titanium Dioxide Composite And Its Photocatalytic Killing Effect On Hela Cells

As a typical n-type semiconductor photocatalytic material,nano-TiO₂ has great appli-cation potential in the field of biomedicine,especially in the cancer treatment,due to its advantages of non-toxicity,low cost,good biocompatibility,light corrosion resistance,and repeatability.However,due to its high band gap（3.0-3.2eV）,it can only absorb UV light（only 3～5% of sunlight）,which is not only harmful to human body,but also has very limited penetration into biological tissues.In addition,it does not have the targeting effect on cancer cells and cannot achieve the precise treatment requirements for cancer.To further develop the application value of TiO₂ in photocatalytic treatment of cancer.In this paper,N-TiO₂ with visible light response capability is first prepared by non-metallic N doping.Secondly,magnetic nanocomposite TiO₂/SiO₂/Fe₃O₄ was prepared with SiO₂/Fe₃O₄ composite.Finally,nanocomposites N-TiO₂/SiO₂/Fe₃O₄ with visible light response and magnetism were prepared by N doping and the introduction of SiO₂/Fe₃O₄.XRD,IR,XPS,UV-vis,FL and other methods were used to study its structure,morphology,magnetism,surface chemical composition and optical characteristics,and its application in the field of cancer treatment was discussed through the study of the photocatalytic killing effect of HeLa cells.The main study of the full text is as follows:1.Preparation,characterization and photocatalytic effect of non-metallic N-doped TiO₂ on HeLa cells.N-TiO₂ was prepared by a simple one-step sol-gel method using ammonia as the nitrogen source and butyl titanate（TBOT）as the precursor.The structure,optical properties and surface chemical composition of N-TiO₂ were analyzed by XRD,IR,XPS,UV-vis,FL and other methods.The characterization results show that effective N doping can not only extend the photoresponse range of TiO₂,but also inhibit the recombination of photogenerated electron-hole pairs.The photocatalytic killing effect of HeLa cells in vitro showed that the photocatalytic anticancer activity of N-TiO₂was better than that of pure TiO₂.When the concentration of N-TiO₂ photocatalyst was 500μg/mL,the survival rate of HeLa cells was as low as 24.15%after irradiation with xenon lamp（light intensity 10mW/cm²）for 2.5h.2.Preparation,characterization and photocatalytic effect of magnetic nanocomposite TiO₂/SiO₂/Fe₃O₄ on HeLa cells.Firstly,magnetic nano-Fe₃O₄ was prepared by co-precip-itation method.Then,a layer of inert SiO₂ was coated on the surface of nano-Fe₃O₄particles by St?ber method.Finally,nano-composites TiO₂/SiO₂/Fe₃O₄ with different TiO₂ loading were prepared by sol-gel method.The magnetic properties,structure,morphology,optical properties and chemical composition were analyzed by XRD,IR,XPS,UV-vis,FL and other methods.The characterization results show that the outermost layer of the nanocomposites is loaded with anatase-type titanium dioxide,and the introduction of SiO₂/Fe₃O₄ makes the nanocomposites not only have visible light absorption ability,but also have magnetism guided by external magnetic field.The results of photocatalytic killing effect of HeLa cells in vitro showed that there was a correlation between the loading of TiO₂ and the killing rate of HeLa cells.The results of in vitro killing effect evaluation showed that when the concentration of the nanocomposite TiO₂/SiO₂/Fe₃O₄ was 500μg/mL and TiO₂loading of 60%,the inhibition rate of HeLa cells was 61.25%after irradiation with xenon lamp（light intensity 10mW/cm²）for 2.5h.3.Preparation,characterization and photocatalytic killing of HeLa cell effects of visible light responsive magnetic nanocomposite N-TiO₂/SiO₂/Fe₃O₄.First,nano-Fe₃O₄ particles were prepared by co-precipitation method.Next,a layer of inert SiO₂ was coated on the Fe₃O₄ core with St?ber method at room temperature.Finally,N-TiO₂/SiO₂/Fe₃O₄was prepared by loading the last layer of N-TiO₂onto SiO₂/Fe₃O₄ by sol-gel method.The morphology,structure,chemical composition,magnetic properties and optical properties were analyzed by XRD,IR,XPS,UV-vis,FL and other methods.The results show that N-TiO₂/SiO₂/Fe₃O₄ has a unique core-shell structure with an average particle size of about34.8 nm.The introduction of SiO₂/Fe₃O₄ makes TiO₂ magnetic with the maximum specific saturation magnetization is 4.87emu·g^-1;N-doping and the introduction of SiO₂/Fe₃O₄ not only makes TiO₂visible-light responsive,but also enhances its photocatalytic activity.Further studies on the photocatalytic killing effect of HeLa cells in vitro showed that the inhibition rate of HeLa cells of nanocomposite N-TiO₂/SiO₂/Fe₃O₄ was stronger than pure TiO₂,and the inhibition rate of HeLa cells reached 67.97% when the nanocomposite N-TiO₂/SiO₂/Fe₃O₄ with 500ug/mL concentration was irradiated by xenon lamp（10mW/cm²）for 125 minutes.