Prepartion Of Titanium Dioxide Based Composite Photothermal Materials And Its Application In Tumor

As a disease with high mortality rate,cancer is a great threat to people's life and health.Photothermal therapy(PTT),as a minimally invasive and accurate method of cancer treatment,has attracted great attention in recent years.PTT is a therapeutic process in which the light energy irradiated on the tumor site is converted into heat energy through photothermal reagents to conduct regional heating and ablate tumor cells.Compared with other wavelengths,Near-infrared light(NIR)has strong skin penetration and high maximum permissible irradiation intensity,so a good photothermal agent should have high absorbance in the NIR range.At the same time,A photothermal reagent that combines chemotherapy,immunotherapy,photodynamic or chemodynamic therapy can avoid the limitations of uneven tissue heating and limited photothermal conversion efficiency in the photothermal process through synergistic effect,and achieve more effective photothermal therapy effect.Among all kinds of photothermal reagents,semiconductor nanomaterials are favored by researchers because of their simple preparation and low price.Titanium dioxide(TiO₂)is a low-cost,safe,non-toxic,biocompatible semiconductor material,widely used in the fields of photocatalysis,antibacterial,drug transportation.In recent years,researchers have expanded the absorption spectrum of TiO₂ from the ultraviolet region to the visible region by changing the type of surface carriers,which has broadened the road for its photochemical application.Based on this,starting from the spectral absorption regulation of TiO₂,this paper prepared NIR excited TiO₂-based composite photothermal conversion materials by constructing heterojunction and realized the combination therapy with photothermal,chemotherapy and photodynamic therapy.Subsequently,the performance of TiO₂-based composite photothermal materials and the therapeutic effect of tumor cells were evaluated.(1)Preparation of TiO₂@RuO₂ nanoflowers and their application in tumor therapy.The integration of chemotherapy,photodynamic therapy and photothermal therapy into one kind of nanoparticles can effectively complement each other in function and improve the therapeutic effect of tumor.In this chapter,RuO₂ nanocrystals were grown in situ on the surface of TiO₂ by hydrothermal method.On the one hand,the formation of RuO₂ enables the materials to have high photothermal conversion efficiency;On the other hand,the formation of heterojunction between RuO₂and TiO₂ changes the electron-vacancy distribution on the surface of TiO₂,so that the material can produce photodynamic effect in the NIR region.At the same time,the generation of RuO₂ gives the activity of peroxidase and catalase to the material,which can decompose H₂O₂ to produce·OH and O₂,which not only provides the oxygen source for photodynamic,but also accelerates the decomposition of H₂O₂ and the circulation of blood O₂ under the condition of overheating,and plays a mutually promoting role.In addition,the high specific surface area of the TiO₂@RuO₂composite structure provides the possibility for the loading and transportation of DOX.CCK experiments on He La and L929 cells showed low cytotoxicity.Subsequently,in vitro killing experiments of tumor cells and AM/PI staining of dead cells proved that DOX loaded TiO₂@RuO₂ nanoflowers can be an effective treatment for tumor cells.In conclusion,TiO₂@RuO₂ nanoflowers are a kind of multi-mode synergistic and highly effective photothermal reagents,which have a good therapeutic effect on tumor cells.(2)Synthesis of TiO₂@CuS nanoflowers and study on photothermal-photodynamic properties.TiO₂ is a typical semiconductor material.It has the advantages of safety,non-toxic,high chemical stability and good biocompatibility.However,the application of TiO₂ is usually carried out under the condition of ultraviolet light,but ultraviolet light has serious damage to biological tissue,so the application of TiO₂ in biological aspects is limited.In this chapter,CuS was generated in situ by surface functionalization of TiO₂,and the TiO₂@CuS nanocomposite structure was successfully prepared.Because of the functional groups on the surface,TiO₂@CuS has good dispersibility in aqueous solution.And under the irradiation of 1064 nm laser(1 W/cm²),TiO₂@CuS has the synergistic effect of photothermal conversion effect and photodynamic effect,and the photothermal conversion efficiency can reach 31.67%,it shows that the material has potential therapeutic effect on tumor cells.