Hong Ling Liu

Synthesis of streptavidin-FITC-conjugated core-shell Fe3O4-Au nanocrystals and their application for the purification of CD4+ lymphocytes

We explored the feasibility of magnetite (Fe(3)O(4))-gold (Au) core-shell nanocrystals as a useful vehicle for biomedical application such as cell separation. Streptavidin-fluorescein isothiocyanate (STA-FITC) was conjugated to the surface of the Fe(3)O(4)-Au core-shell nanocrystals using a carbodimide activation protocol. These nanocrystals were further tested for their ability to bind CD4+ T lymphocytes, bound to biotin-labeled anti-CD4 mAbs, isolated from the spleen of C57BL/6 mice. Our data show that the Fe(3)O(4)-Au nanocrystals successfully pulled down CD4+ T lymphocytes from the whole splenocytes with high specificity. Therefore, our nanocrystals provide an efficient tool for the cell separation process and further present the dramatic potential to be applied to other areas of biomedical application including diagnosis, monitoring, and treatment of human diseases.

Synthesis of monosized magnetic-optical AuFe alloy nanoparticles

We report the preparation and characterization of multifunctional AuFe alloy nanoparticles of three compositions, Au0.25Fe0.75, Au0.5Fe0.5, and Au0.75Fe0.25, by a polyol process. It is found that the fusion of the two elements into one nanostructure entity retains the optical and magnetic properties of the individual components. The x-ray diffraction and transmission electron microscopy analyses confirm the formation of the alloy nanostructure with a narrow distribution of particle sizes and provides the detailed structural arrangements. The magnetic investigation shows the superparamagnetic or soft ferromagnetic behavior of the nanoparticles at room temperature, whereas the UV-visible measurements display the variation of the absorption bands at ∼560nm. The AuFe nanoparticles are rendered water soluble after thiolation.

Non-aqueous synthesis of water-dispersible Fe3O4–Ca3(PO4)2 core–shell nanoparticles

The Fe(3)O(4)-Ca(3)(PO(4))(2) core-shell nanoparticles were prepared by one-pot non-aqueous nanoemulsion with the assistance of a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO), integrating the magnetic properties of Fe(3)O(4) and the bioactive functions of Ca(3)(PO(4))(2) into single entities. The Fe(3)O(4) nanoparticles were pre-formed first by thermal reduction of Fe(acac)(3) and then the Ca(3)(PO(4))(2) layer was coated by simultaneous deposition of Ca(2+) and PO(4)(3-). The characterization shows that the combination of the two materials into a core-shell nanostructure retains the magnetic properties and the Ca(3)(PO(4))(2) shell forms an hcp phase (a = 7.490 Å, c = 9.534 Å) on the Fe(3)O(4) surface. The magnetic hysteresis curves of the nanoparticles were further elucidated by the Langevin equation, giving an estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. Fourier transform infrared (FTIR) analysis provides the characteristic vibrations of Ca(3)(PO(4))(2) and the presence of the polymer surfactant on the nanoparticle surface. Moreover, the nanoparticles could be directly transferred to water and the aqueous dispersion-collection process of the nanoparticles was demonstrated for application readiness of such core-shell nanostructures in an aqueous medium. Thus, the construction of Fe(3)O(4) and Ca(3)(PO(4))(2) in the core-shell nanostructure has conspicuously led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.

Effects of Cu doping on the microstructure and magnetic properties of CoPt nanowires

We studied the effects of copper doping on the microstructure and magnetic properties of CoPt nanowires fabricated in anodized aluminium oxide (AAO) nanotemplates by electrodeposition. The morphological observation indicates well-formed CoPt and CoPtCu nanowires, while the structural analysis shows that fcc-Co3Pt phase exists prior to annealing and is retained in the doped nanowires, with minor hcp-CoPt phase postannealing. The doping causes shrinkage of the lattice spacing prior to annealing due to the insertion of smaller copper atoms. Compared to the undoped CoPt nanowires, the magnetic measurements reveal significant enhancement in the magnetic properties of the CoPtCu nanowire postannealing, resulting in the more rapid increase in the coercivity with annealing temperature.

Fabrication of Multifunctional Au Doped CoPt Nanowires

Au-doped CoPt nanowires were prepared in anodized aluminum oxide (AAO) nanotemplates by electrodeposition and the doping effects on their microstructure and magnetic properties were investigated. Dependent on the deposition conditions, the CoPtAu nanowires can have the cubic or tetragonal phase. The magnetic measurements indicate that the nanowires demonstrate ferromagnetic behavior, showing the easy axis along the direction of the nanowires and strong enhancement in coercivity and squareness prior to annealing, whereas the optical measurements reveal plasmon resonances characteristic of nanostructured Au.

Giant Diamagnetism in AuFe Nanoparticles

Multifunctional Au_0.5Fe_0.5 alloy nanoparticles from a polyol process were investigated, showing the alloy nanostructures with the formation of a new phase and twin microstructures. Giant diamagnetism, on the order of -10^- ² emu g^-1 Oe^-1 , is observed in the zero-field cooled process of the nanoparticles, which is modeled in terms of the spin-orbital interactions tuned by the modified potential energy as a result of the shrinking dimension, peculiar disordered microstructure, and heterogeneous elemental composition.