Multifunctional core–shell particles composed of magnetic particles covered with a gold nanoshell can be induced to align into conducting lines upon application of a magnetic field (see Figure). The formation of Au clusters and “streaky” gold nanoparticles on the surface of the PS beads is demonstrated and the preparation, characterization, and applications of magnetic and polystyrene beads featuring a gold shell are addressed.

Negatively charged luminescent CdSe−ZnS quantum dots (QDs) were successfully incorporated into novel luminescent glyconanopsheres averaging 190 nm in diameter through electrostatic interactions with carboxymethyldextran (CM-dextran) and polylysine. In addition to electrostatic attraction between the negatively charged dextran, the negatively charged CdSe−ZnS QDs, and the positively charged polylysine, covalent amide bonds were introduced to cross link the QDs with the polysaccharide matrix to further stabilize the nanospheres. The dextran residues on the surface of the nanospheres show high affinity toward the glucose binding protein-Concanavalin A (Con A). As a result, these luminescent CdSe−ZnS QD incorporated glyconanospheres are a useful tool for studying carbohydrate−protein interactions that are critical steps in bacterial and viral infection.

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Dynamic magnetic properties of spins from Mn ions doped in semiconductor nanocrystals (Cd1−xMnxSe) have been studied using an electron paramagnetic resonance method based on two different crystalline sizes and a series of Mn concentrations. By decreasing the size of the quantum dots, the electron spin-nuclear spin interactions are reduced due to enhanced magnetic interactions between Mn ions. A linewidth analysis was also carried out, showing longer spin relaxation times and supporting the enhancement of spin coherence. We suggest that the enhancement of Mn–Mn interactions results from the quantized electrons which have longer coherence length in quantum dots. Quantum size effects may benefit to control and manipulation of spins in a semiconductor nanocrystalline system in which the magnetic ions are incorporated.

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We herein report a preparation process of Co-doped anatase TiO 2 nanobelts facilely combining ion-exchange with hydrothermal treatment. A series of TiO 2 materials with different Co 2+ contents were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier transform infrared (FT-IR), and magnetic measurement techniques. The results show that Co 2+ cations have doped into the TiO 2 lattice structure and that any metallic cobalt clusters or nanoparticles could not be found. The magnetic result demonstrates that the prepared Co-doped TiO 2 samples are room-temperature ferromagnetic materials, whereas with the increase of Co 2+ content, the remnant magnetization tends to decrease due to the superexchange coupling interaction between Co 2+ ions owing to the ununiform distribution.

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