Preparation And Properties Of Iron Oxide/Rare Earth Luminescence Materials/Noble Metal Tirfunctional Nanocomposites

Multifunctional hybrid nanocomposites have important practical significance and potential applications in many different fields including materials, physics, chemistry, biology and medical science. Due to unique optical properties of lanthanide doped nanocrystals, they have obvious advantages and wide range of applications, espectilly the application of upconversion nanomaterials in bioimaging and medical diagnostics. The localized surface plasmon resonance of noble metal nanocrystals could bring about efficient photothermal transduction and energy transfer with the nearby luminescence nanocrystals. In addition, iron oxide(Fe3O4) nanoparticles provide an additional magnetic functionality for the hybrid nanocomposites. It is expected that the multifunctional hybrid nanocomposites of luminescence-photothermal-magnetic perhaps open exciting opportunities in the biomedical fields of imaging, sensing, separation and thermal therapy.In this work, we designed facile solution route to synthesize a series of hybrid core-shell structure nanocomposites such as Ag/Au@Na YF4:Tb3+, Au@Na YF4:Yb3+,Er3+/ Ho3+, Au NRs@Na Gd F4:Yb3+,Er3+, Fe3O4@Au@Na YF4:Tb3+/Yb3+,Er3+ combining rare earth doped luminescence materials(Na YF4:Tb3+, Na YF4:Yb3+,Er3+, Na YF4:Yb3+,Ho3+, Na Gd F4:Yb3+,Er3+), noble metal nanoparticles(Au, Ag) and Fe3O4 nanoparticles. The morphology, structure and composition of the core-shell hybrid nanocomposites were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectrum(XPS). The luminescence, magnetic, photothermal transduction and biocompatibility were characterized by photoluminescence(PL) spectra, and vibrating sample magnetometer(VSM) and methyl thiazolyl tetrazolium(MTT) assay, respectively. The results indicate that as-synthesized nanocomposites have luminescence, magnetic and photothermal transduction property. For the core-shell system including luminescence nanocrystals and noble metal nanoparticles, the luminescence resonance energy transfer(LRET) was demonstrated, in which noble metal nanoparticles as luminescence quenchers absorb the emission energy of the Na YF4:RE3+ donor. The LRET could be found in the systems of Ag/@Na YF4:Tb3+, Au@Na YF4:Yb3+,Er3+/Ho3+ and Au NRs@Na Gd F4:Yb3+,Er3+. Moreover,the hybrid nanocomposites have an efficient photothermal transduction property due to the present of Au nanocrystals, and the temperature of photothermal transduction can be easily controlled by adjusting the concentration of nanocomposites under 980 nm laser irradiation. In addition, incorporation of Gd3+-based materials with paramagnetic properties or Fe3O4 magnetic nanoparticles provides an additional functionality to the nanocomposites. The as-synthesized multifunctional nanocomposites have also shown good biocompatibility, which is essential for further biological applications.