Study On The Preparation Of ZnO Nanostructures And Their Biomedical And Photocatalytic Applications

Zinc oxide (ZnO) has a wide band gap (～3.37eV) and high exciton binding energy (～60meV) at room temperature, which shows good optical, electronic and catalytic properties. Combined the merits of nanoscale materials, ZnO nanostrctures demonstrate unique properties in magnetic, optic, electricity and gas sensitive, which the bulk ZnO does not own. These special properties have made the nano-ZnO being widely used in solar cells, piezoelectric materials, gas sensitive materials, catalytic materials, biomedicine, and so on. In this paper, we have synthesized ZnO nanostructures with various morphologies of by sol-gel and hydrothermal method, and studied their possible applications in biomedicine and photocataly. The main results are as follows:(A) Preparation of ZnO nanoparticles (NPs) and their application in biomedicine.1. Preparation and functionalization:The ZnO NPs were synthesized by sol-gel method; Then the NPs were functionalized by connecting (3-aminopropyl) triethoxysilane(APTES).2. Characterization:The APTES-ZnO NPs were characterized using TEM, DLS,XRD, FTIR, UV-VIS absorption, PL and PL excitation spectra.3. Cytotoxicity test:We have investigated the MCF-7cell (breast cancer cells) viability as a function of the APTES-ZnO concentration. When the concentration of APTES-ZnO NPs is lower than30mg·L-1, the cell viability remains to be80%.4. Photodynamic treatment by using APTES-ZnO NPs:The results show that longer irradiation time and higher concentration of APTES-ZnO NPs, will result in less cell viability of MCF-7cells. When the concentrate of APTES-ZnO NPs is30mg·L-1and the illumination time for5min, the cell activity was about60%.(B) Preparation and photocatalytic properties of ZnO nanostructures (disk-like ZnO, flower-like ZnO and rod-like ZnO).1. Preparation of disk-like, flower-like and rod-like ZnO nanostructures:The ZnO nanostructures were prepared using hydrothermal method. The morphology of ZnO is dependent on the ratio of reactants. The micro/nanostructures were characterized by SEM and XRD spectroscopy.2. Luminescent properties of the ZnO nanostructures:PL results show that the alkali have great effects on the defect luminescence.3. The photocatalytic properties:Photodegradation properties of ZnO nanostructures were evaluated by their ability to degrade the dye molecules, methylene blue (C16H18CIN3S, MB). The results show that disk-like nano-ZnO has the highest catalytic effect.4. Growth mechanism:Based on the experimental results, the possible growth mechanism of ZnO nanostructure was discussed.(C) Preparation and characterization of ZnO nanowire (ZnO NW) films.1. The preparation of ZnO NWs:The ZnO NWs were prepared using zinc nitrate hexahydrate and hexamethylenetetramine (HMT) by hydrothermal method.2..Characterization of ZnO NWs:The structure was characterized by using XRD, SEM, and Raman spectra.