Synthesis And Property Studies Of Nanoparticles For Biomedical Applications

Owing to the extraordinary nanostructure, the multicomponent nanomaterials which not just maintainthe functionality and nanoscale charaters of the respective components, but also appeare some novel anddiversification of special performance and potential development unlike the various compontent, have farmore applications than the single component nanomaterials in the nanoscience and technology field.On account of the study magnetic materials, iron oxide and gold nanoparticles, the composite of thesetwo materials has aroused a wide range of interests. It is foreseen that amalgamation of these two elementsinto a single block on the nanoscale should produce a new nanostructured material retaining the optical andmagnetic properties of the respective components, synergistically proffering enhanced performance andfunctionalities which go beyond those of the individual components. The nanoparticles modified by thebio-friendly molecules were provided with better water-solubility and biocompatibility, easy linking to thebiological macromolecules. Thus the nanoparticles are expected to have more broad application prospectsin the field of biomedicine. The nanoparticles used in biomedical research are always performed in aqueousor in humoral. But the nanoparticles prepared by common way just could be dispersed in the organicsolvent. Thus the nanoparticles which can be easily dispersed in the water are still necessary.In this work, the bi-phase dispersible nanoparticles were prepared by the one-pot nanoemulsionprocess using two kinds of bio-friendly polymer molecules as surfactants. The nanopareticles not only havegood dispersibilty and stability in the organic solvent （hexane）, bur also posess excellent dispersibilty andstability in the inorganic solvent （water）. The main results of my work are summarized as follows:1. Synthesis and characterization of the bi-phase dispersible ZnO nanoparticlesBi-phase dispersible ZnO nanoparticles were synthesised in the presence of PVP andPEO-PPO-PEO polymer as the surfactant by using the nanoemulsion process. The FTIR assessment showsthe polymer molecules are acturally present on the surface of the nanoparticles; The X-ray diffraction（XRD） and transmission electron microscopy （TEM） measurements reveal the hexagonal structure andhigh crystallinity of the nanoparticles. It is also found that the nanoparticles are well dispersibleeither in an inorganic solvent （water） or in an organic solvent （hexane）. The UV-Vis absorptionspectra show that the products have strong absorption. PL spectra prove that under380nm excitation the PVP-ZnO nanoparticles have strong blue-greenish emission and weakyellow-greennish emission at room temperature. The nanoparticles would have wide potentialapplication in the optical semiconductor and pharmaceutical field.2. Synthesis and characterization of the bi-phase dispersible and magnetic-optical Fe₃O₄/Au core-shellnanoparticlesThe spherical monodispersed Fe₃O₄/Au core-shell nanoparticles were prepared by the one-potnanoemulsion method with the different polymers as the surfactant. The FTIR measurment shows thepolymer molecules are acturally present on the surface of the nanoparticles. The TEM and XRD analysesconfirm the formation of the core-shell nanostructure and the well monodispersity. The UV-Vismeasurements show that the nanoaparticles can be directly dispersed in water, and possess excellentoptical property and dispersibilty in both inorganic solvent （water） and organic solvent （hexane）. Thevibrating sample magnetometry （VSM） measurement manifests a soft ferromagnetic behavior of thenanoparticles with a small coercivity at room temperature. Also the nanoparticles possess a rapid, efficientand reversible dispersion-collection process with an external magnetic field. Due to the high affinity of thestreptavidin, the multifunction Fe₃O₄/Au core-shell nanoparticles modified by the streptavidin-fluoresceinisothiocyanate, could easily link to the biological macromolecules, which is expected to be used inbiomedical including cell separation, diagnosis, monitoring and treatment of human disease.3. Synthesis and characterization of the bi-phase dispersible and magnetic-optical FeAu alloy nanoparticlesThe bi-phase dispersible AuFe alloy nanoparticles were synthesised in the presense of polymersurfactant through a non-aqueous nanoemulsion prossess. The FTIR study proves the polymer moleculescoating on the surface of the nanoparticles, whereas the structural, magnetic, and optical analysisesillustrate the fusion of iron and gold into one single nanostructure. The TEM and size distribution show thenanoparticles are uniform, almost sphorial, and have a tight size distribution. The UV-Vis measurementsdisplay the excellent optical property of the nanoparticles which have a surface plasmon absorption bandwithin550nm⁵80nm. The vibrating sample magnetometry （VSM） manifests a soft ferromagneticbehavior with a small coercivity of the nanoparticles at room temperature. The magnetic hysteresis curvesare effectively assessed by modified bi-phase Langevin equations, which are satisfactorily explained interms of a bimodal particle size distribution. As the result of the coating of surfactant, the nanoparticles own favourable water-solubility and biocompatibility, either in an inorganic solvent （water） or in anorganic solvent （hexane）. The dispersibilty and the magnetic properties are demonstrated by the rapid,efficient and reversible dispersion–collection process of the nanoparticles in solution, which promisepotential applications such as optical sensing, photonic therapy, magnetic separation and drug delivery.