Preparation Of ZnO Nanomaterials And Their Biological Effects

During the past few decades,nanotechnology has been a research hotspot in materials science,touching upon multiple disciplines.It has been widely used in various fields of human life.In these fields,nanomedicine has attracted the attention of researchers for the treatment of tumors.Composite nanoparticles can be used drug carriers.Zinc oxide nanomaterials can be used as a drug carrier because of their biocompatibility,low toxicity and anticancer.This article intends to study the preparation conditions and principles of zinc oxide nanomaterials,and to explore the direction of antibacterial and drug carriers in biological applications.The results obtained in this thesis could provide some guidelines for the preparation and application of zinc oxide materials.Firstly,ZnO nanoparticles with particle size of 40?60 nm were synthesized by a hydrothermal method,using Chlorella extract as additive.After heat treatment,the organic functional groups in the Chlorella vulgaris extract bound on the surface of the zinc oxide nanoparticles are carbonized,so that the morphology of the zinc oxide changes from the original sheet-like structure to a nearly spherical structure.It can be concluded from the antibacterial experiment that ZnO QDs have a certain antibacterial effect,with a minimum inhibitory concentration of 10 mg mL^-1.Secondly,Zinc oxide quantum dots were prepared by a sol-gel method.The effects of different alkali hydroxides(Li OH,Na OH,KOH)and R_Zn-OH(representing the molar ratio of Zn²⁺and OH^-)on the morphology and properties of the quantum dots were investigated.The results show that the size of the quantum dots prepared with alkali hydroxide as Li OH is smaller than that prepared with Na OH and KOH;the fluorescence intensity of quantum dots prepared by R_Zn-OH=1:1 was strong in aqueous solution.The QDs prepared by R_{Zn-Li OH}=1:1 were modified by APTES and had the characteristics of water solubility,stable yellow fluorescence,good dispersion and regular morphology.The antimicrobial properties of ZnO nanomaterials and ZnO quantum dots were compared.The minimum antimicrobial rate of the quantum dots prepared under the condition of R_{Zn-Li OH}=1:1 against S.aureus was 1.25 mg mL^-1,and the antibacterial effect is 8 times that of zinc oxide nanomaterials.Furthermore,zinc oxide quantum dots have acid response characteristics,and modifying them with APTES,PEG and HA.Nanocomposite drug delivery materials with water solubility,biocompatibility and targeting property were synthesized.The results showed that the drug loading efficiency and drug loading rate of the drug loading system were 80%and 16%respectively;simulating the internal environment,70%of DOX in the PBS dialysate at p H=5.0 is and 32%of DOX in the PBS dialysate at p H=7.4 is released from the drug-carrying system Release;when the concentration of Zn²⁺>40?g mL^-1,the survival rate of A549 cells is less than 40%,which proves that Zn²⁺decomposed by ZnO QDs in the tumor environment is toxic to cells;when DOX content reached 6.17?g mL^-1,the survival rate of A549 cells was20?35%,and that of Hela cells was 60?70%.The system can stably exist in the normal neutral environment of the human body and achieve targeted recognition of A549 and Hela cells.Lastly,to improve the fluorescence characteristics of zinc oxide quantum dots to achieve bioluminescence labeling and drug tracking.Rare earth doping experiments were carried out in this work.Because rare earth ions have abundant 4f-4f or 4f-5d transitions,they are considered as potential luminescent center materials for doped II-VI nanomaterials.Therefore,the optical properties of doped rare earth on ZnO quantum dots under ultraviolet light have been studied.The results show that the rare earth ions(Yb³⁺,86.8 pm;Sm³⁺,95.8 pm;La³⁺,103.2 pm;Zn²⁺,74 pm)affect the defect concentration of quantum dots and then their fluorescence intensity.Under the condition of 2 mol%low concentration doping,doping La³⁺makes the luminous intensity of ZnO quantum dots is enhanced,and the doping of Yb³⁺or Sm³⁺makes the luminous intensity of ZnO quantum dots weaker.