Functionalization Of Magenetic Nanoparticles Via Click Chemistry:Preparation, Characterization And Application

Recently, magnetic nanoparticles have attracted attention because of their superparamagnetic and the biocompatibility. The synthesis, characterization and application of magnetic nanoparticles have been the focus of many fields, such as chemistry, material, biology, environment and medicine. To meet the demand for the rapid development and potential application, the magnetic nanoparticles with tailored structural and appropriate surface chemistry are very important to improve their dispersivity, solubility and function. Thus, the efficient, simple and general strategy for functionalization of magnetic nanoparticles is very necessary for expanding their applications. Click chemistry, which was developed by Professor Sharpless, the winner of Nobel Prize in Chemistry2001, is a good choice for the functionalization of magnetic nanoparticles because of its mild reaction condition, excellent chemoselectivity, high yields and a great degree of solvent and pH insensitivity.In this work, the magnetic nanoparticles were functionalized with fluorescent dyes, graphene oxide or anti-bacterial reagents, respectively via click reaction, and various magnetic nanocomposites were achieved. The characterizations and applications of these magnetic nanocomposites were investigated. The content of this doctoral thesis was listed as following.Chapter1:PrefaceThe synthesis, modification and application of magnetic nanoparticles, as well as the graphene oxide, have been reviewed. The characteristics, reaction types and the application of click chemistry were also introduced. Chapter2:Rhodamine-B decorated superparamagnetic iron oxide nanoparticles: preparation, characterization and their optical/magnetic propertiesThis chapter reports on covalent clicking of rhodamine-B (RhB) bearing a terminal azide group to alkyne-terminated silica coated superparamagnetic iron oxide nanoparticles via the copper (I)-catalyzed Huisgen azide-alkyne1,3-dipolar cycloaddition (CuAAC) reaction. The course of the reaction was followed the usage of powder X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, fluorescopy, and magnetics. The RhB labelled Fe3O4@SiO2nanoparticles exhibit stable fluorescence and no detectable leakage of the fluorescent dye because the resulting1,4-disubstituted1,2,3-triazole ring formed via click reaction is thermally stable and relatively inert to hydrolysis, oxidation, and reduction. Due to the superparamagnetic property of the Fe3O4and the RhB molecule covalently decorated in the Fe3O4@SiO2framework, the nanoparticles are endowed with properties of a contrast agent in magnetic resonance imaging (MRI) and optical imaging modality. The cytotoxicity tests indicate the bifunctional nanoparticles could be applied in biomedical or bioengineering field.Chapter3:Bacitracin peptide conjugated superparamagnetic iron oxide nanoparticles:synthesis, characterization and antibacterial activityIn this work, bacitracin peptide conjugated superparamagnetic iron oxide nanoparticles have been prepared via click chemistry and the biocidal activity is investigated. First, water-soluble iron oxide (Fe3O4) nanoparticles were synthesized by coating iron oxide nanoparticles with a hydrophilic, biocompatible polymer, poly (acrylic acid)(PAA), through the carbodiimide reaction, obtained the propargylated Fe3O4/PAA nanoparticles. Then, through the PEG and carbodiimide reaction, N3-bacitracin was obtained. Finally, by click chemistry, the magnetic nanoparticles successfully achieved biofunctionalized, the bacitracin/Fe3O4nanocomposites were prepared. Cell cytotoxicity test indicates that the bacitracin peptide conjugated Fe3O4nanoparticles incubated with human fibroblasts cells show very low cytotoxicity even at relatively high concentrations. In view of the antibacterial activity of bacitracin peptide, the biofunctionalized Fe3O4nanoparticles exhibit very excellent antibacterial effect, even higher than that of bacitracin peptide itself.Chapter4:Synthesis and characterization of magnetic graphene oxide/nanocompositesWe report a facile approach to synthesize graphene oxide (GO)/Fe3O4nanocomposites by click chemistry. Firstly, organophosphorus reagent with azide-group was synthesized and grafted onto the surface of magnetic nanoparticles. Then, alkyne-terminated graphene oxide was obtained through the acylation and substitution reaction. Finally, the GO/Fe3O4nanocomposites were prepared by click chemistry for the first time. The nanocomposites show good solubility and superparamagnetic, indicating the potential applications in biomedicine and environmental sewage treatment.Chapter5:Preparation of polyacrylic acid/graphene oxide/Fe3O4nanocomposites for recyclable removal of heavy metal ionsPAA/GO/Fe3O4nanocomposites have been synthesized and used as adsorbents for removal of heavy metal ions from waste water. The effects of pH, the amount of the nanocomposites, temperature, as well as other factors on the efficiency of removal of Cd2+, Pb2+and Cu2+were investigated. The experimental results show that under the optimized experimental conditions, the capture efficiency of PAA/GO/Fe3O4nanocomposites for Cd2+, Pb2+and Cu2+were90%,95%and89%, respectively. In addition, the magnetic nanocomposites can be used as a recyclable tool for removal of heavy metal ions. After5cycles, the capture efficiency of the PAA/GO/Fe3O4nanocomposites for Cd2+, Pb2+and Cu2+ions is still over80%.Chapter6:Vancomycin grafted magnetic graphene oxide nanocomposites: synthesis, characterization and antibacterial activityThrough the amidation reaction, vancomycin was covalently grafted on GO/Fe3O4nanocomposites. The cytotoxic and antimicrobial properties of the nanocomposites were investigated. Cell cytotoxicity test indicates that vancomycin conjugated GO/Fe3O4nanocomposites show very low cytotoxicity even at relatively high concentrations. In addition, the nanocomposites display excellent antibacterial activity for gram-positive bacteria and gram-negative bacteria. Even more, the antibacterial tests also show that the vancomycin conjugated GO/Fe3O4nanocomposites have better antimicrobial properties than that of vancomycin, and its minimum inhibitory concentration for E. coli and B. subtilis are3.9and2.0μg/mL, respectively.