Preparation Of Rare Earth Doped Zinc Oxide Quantum Dots And Their Antitumor And Antibacterial Properties

Zinc oxide quantum dots（ZnO QDs）have the advantages of good biocompatibility,unique photoluminescence,p H responsive release,large specific surface area and easy synthesis,and are widely used in biosensors,bioimaging,anti-tumor,antibacterial and other aspects.In recent years,improving the photoluminescence of ZnO QDs in order to expand its applications in bioimaging and biosensors has become a research hotspot.Rare earth doped ZnO QDs,during the doping process,ionic collisions will produce or affect defects.These defects directly affect the electrical,optical and magnetic properties of ZnO materials,and improve the photoluminescence properties of ZnO QDs.Rare earth doping can also cause ZnO to form more oxygen vacancies and produce more reactive oxygen species（ROS）,thus improving the anti-tumor and antibacterial effects.Therefore,rare earth doping is an important modification method to study the photoluminescence and biological applications of ZnO QDs.In this paper,ZnO QDs were doped and modified by La³⁺,Tb³⁺and Nd³⁺plasma.The structure,morphology and photoluminescence properties of the synthesized materials were tested and analyzed by means of XRD,TEM,IR,XPS,PL and UV.Further,the anti-tumor and anti-bacterial effects of rare earth doped ZnO QDs were studied through anti-tumor and anti-bacterial experiments.The study showed that rare earth doped ZnO QDs significantly improved the photoluminescence properties,anti-tumor and anti-bacterial effects of ZnO QDs.The main research contents are as follows:1.Zinc acetate dihydrate,lithium hydroxide as the base,using sol-gel synthesis ZnO QDs,in the synthesis process,doped lanthanum acetate,La-ZnO QDs composite was prepared,detailed study of ZnO QDs,La-ZnO QDs structure and luminescence comparison,the results found that,Lanthanum doping does not change the hexagonal wurtzite structure of ZnO QDs,and greatly improves the photoluminescence properties of ZnO QDs.In the anti-tumor experiment,ZnO QDs was used as the carrier,and the surface modification of ZnO QDs was carried out by using APTES,PEG and HA as modifiers.Then the anti-tumor drug doxorubicin（DOX）was loaded to construct a lanthanum-doped ZnO QDs as the carrier of targeted drug delivery system.The results showed that lanthanum doping did not improve the drug loading ability of ZnO QDs,but improved the anti-tumor effect.By exploring lanthanum-doped ZnO QDs,it is found that lanthanum doping can improve the photoluminescence properties and anti-tumor effects of ZnO QDs.The reason is that lanthanum-doped ZnO QDs can affect the surface defects of ZnO QDs and improve the photoluminescence properties of ZnO QDs.Lanthanum-doped ZnO QDs can decrease tumor mitochondrial membrane potential and enhance the level of reactive oxygen species,thus improving the antitumor effect.2.Doped rare earth lanthanum enhances the active oxygen level of ZnO QDs,which is one of the antibacterial mechanisms of ZnO QDs.In the second stage,we explored the antibacterial properties of different rare earth doped ZnO QDs.Similarly,ZnO QDs are synthesized by sol-gel method with zinc acetate dihydrate and lithium hydroxide as the base.In the synthesis process,La-ZnO QDs,Nd-ZnO QDs,Tb-ZnO QDs are prepared successfully by doping lanthanum nitrate,neodymium nitrate and terbium nitrate.La-ZnO QDs,Nd-ZnO QDs,and Tb-ZnO QDS are studied in detail.Comparing the structure and luminescence of Tb-ZnO QDs with ZnO QDs,the results show that doping of three rare earth elements does not change the hexagonal woltzite structure of ZnO QDs,but the photoluminescence properties of ZnO QDs are improved,among which Tb-ZnO QDS has the strongest photoluminescence properties.The antibacterial effect of La-ZnO QDs,Nd-ZnO QDs,Tb-ZnO QDs and ZnO QDs on Staphylococcus aureus was investigated by plate counting method.The results showed that doping of three rare earth elements can improve the antibacterial effect of ZnO QDs,among which Nd-ZnO QDs has the strongest antibacterial effect.3.ZnO QDs is a promising photocatalytic material in semiconductor materials.ZnO QDs,a direct wide-band gap semiconductor,is a typical multifunctional metal oxide material with unique physical and chemical properties such as low toxicity,high photostability,good chemical stability and efficient current-carrying electron mobility,which makes it a great potential in the field of photocatalysis.Photocatalysis is one of the generally recognized mechanisms for producing reactive oxygen species on zinc oxide surface.Therefore,in the third part,we explored the photocatalytic antibacterial properties of ZnO QDs doped with neodymium in different doping amounts.Fluorescence test results show that 4Nd-ZnO has the strongest fluorescence performance,while 8Nd-ZnO has a lower fluorescence performance.The results show that ZnO QDs has strong photocatalytic activity,and neodymium doping greatly enhances the photocatalytic activity of ZnO QDs.When the doping amount of Nd reaches 8%,the antibacterial effect on Staphylococcus aureus with colony number of about 10⁶CFU/m L is the strongest.Therefore,Nd doping enhances the photocatalytic antibacterial performance of ZnO QDs,and the antibacterial effect is proportional to the doping concentration.