Photocatalytic Drug Release And Antibacterial Properties Based On Titanium Dioxide Nanotubes

The excellent photocatalytic activity of titanium dioxide nanotube materials has a good application prospect in biomedical fields such as pollutant degradation,drug delivery and antibacterial.However,due to its large forbidden band width(rutile 3.0 eV,anatase 3.2 eV),titanium dioxide can only respond to ultraviolet light,but ultraviolet light only accounts for 4%of the total amount of sunlight,making it less efficient for sunlight.In addition,long-term exposure to ultraviolet light can deactivates biomolecules and damages normal biological tissues and organs.At present,a large amount of research has focused on expanding the photoresponse range of titanium dioxide nanomaterials by means of precious metal modification,semiconductor compounding,and dye sensitization.Precious metal nanoparticles(such as Au,Ag)can extend the photoresponse range of titanium dioxide to visible light or even near-infrared light due to their surface plasmon resonance effect(SPR).At the same time,the modification of precious metals can also effectively promote the separation of photogeneration electron-hole pairs,thereby improving photocatalytic activity.Therefore,this paper developed a photocatalytic material that responds in the near-infrared and full spectrum of sunlight through the composite of precious metals and titanium dioxide nanotubes,which provides a new idea for the application of titanium dioxide nanomaterials in biomedical(drug loading/release,antibacterial material).The main contents are as follows:(1)Near-infrared light-infuced drug release system based on asymmetric structure of titanium dioxide nanotubes.Titanium dioxide nanotubes with asymmetric structure were prepared by using the structural characteristics of spaced titanium dioxide nanotubes and the"irrigation" technique.And the system consists of a near-infrared light response region outside the nanotubes and a drug loading region within the nanotubes.The combination of upconversion nanomaterials and Pt-SPR enables the system to respond to near-infrared light for release of antimicrobial agents.The experiment used kanamycin as an antibacterial drug model to investigate the drug release of the system under near-infrared light irradiation and the antibacterial condition of the system in the presence or absence of drug loading.The experimental results show that the system has a good near-infrared light response,and a large amount of active oxygen species that can be generated under near-infrared light can effectively cut off the covalent bonds connecting the drug to the tube wall,and the drug can be controlledly released.At the same time,the produced reactive oxygen species can also destroy the integrity of the bacteria,allowing the drug to quickly enter the bacteria through the damaged part of the bacterial cell wall,thereby accelerating the inhibition of the protein synthesis process and rapidly inactivating bacteria.(2)Seawater desalination and antibacterial system based on titanium dioxide nanotubes.The system consists of a three-dimensional porous structure of Ag/TiO2 nanotube array film.The experimental study on the spectral absorption characteristics of the system,seawater desalination ability and the ability of bacteria in seawater to invade.The experimental results show that the average light absorption rate of the material in the range of 200-2500 nm can reach 80%through the modification of Ag nanoparticles with surface plasmon resonance effect.Under the irradiation of 6 kW m-2,the solar water vapor efficiency of the Ag/TiO2 nanotube array film can reach 80.29%,which realizes the efficient use of solar energy to obtain fresh water.On the other hand,the Ag/TiO2 nanotube array film can effectively utilize ultra violet-visible light in sunlight for photocatalytic reaction.The produced reactive oxygen species(·O2-and ·OH)can destroy the cell wall of bacteria and affect the normal metabolism of bacteria,thereby inactivating the bacteria.After 60 min of simulated sunlight(Copt=1),he 0.3 mg/mL Ag/TiO2 nano tube array film has an antibacterial efficiency of 99.99%,and it has good antibacterial properties after repeated use.The above research results prove that the nanotube array film prepared by us is a recyclable material that can desalinate seawater and also has high efficiency and antibacterial activity,and has a wide application prospect.