A number of proposed next-generation electronic devices, including novel memory elements 1 and versatile transistor circuits 2 , rely on spin currents, that is, the flow of electron angular momentum. A spin current may interact with a magnetic nanostructure and give rise to spin-dependent transport phenomena, or excite magnetization dynamics 1-11 . In contrast to a spin-polarized charge current, a pure spin current does not produce any charge-related spurious effects 12,13 . One way to produce a pure spin current is non-local electrical-spin injection 12-18 , but this approach has suffered so far from low injection efficiency. Here, we demonstrate a significant enhancement of the non-local injection efficiency in a lateral spin valve prepared with an entirely in situ fabrication process. Improvements to the interface quality and the device structure lead to an increase of the spin-signal amplitude by an order of magnitude. The generated pure spin current enables the magnetization reversal of a nanomagnet with the same efficiency as in the case of using charge currents. These results are important for further theoretical developments in multiterminal structures 2 , but also with a view towards realizing novel devices driven by pure spin currents.In a vertical spin-valve nanopillar consisting of a ferromagnet/non-magnet/ferromagnet trilayer, the magnetic state can be switched between the antiparallel and the parallel configurations by applying a charge current [1][2][3][4][5][6][7][8][9][10][11] . This charge-current-induced magnetization switching (CIMS) is the result of a direct transfer of spin angular momentum from the spin current carried along the charge current to the localized magnetic moment in the ferromagnet. Separation of the charge and spin components raises the possibility of chargeless pure spin-current-induced magnetization switching (pure spin CIMS).The pure spin current transfers only spin angular momentum, and thus provides an attractive means to manipulate the magnetic state in magnetic nanostructures as well as a quiet electrical background for experimental studies. The pure spin current I S can be generated by the diffusion of the accumulated spins 12-20 in a metallic lateral spin-valve (LSV) structure with non-local electrical spin injection, as shown in Fig. 1a. When the spin accumulation at the interface between the permalloy (Py) and Cu wires on the detector side is non-collinear to the Py magnetization, the transverse component of the pure spin CuAu Py

Lysozyme monolayer-protected gold nanoparticles (Au NPs) which are hydrophilic and biocompatible and show excellent colloidal stability (at low temperature, ca. 4 degrees C), were synthesized in aqueous medium by chemical reduction of HAuCl4 with NaBH4 in the presence of a familiar small enzyme, lysozyme. UV-vis spectra, transmission electron microscopy (TEM), atomic force microscopy, and X-ray photoelectron spectroscopy characterization of the as-prepared nanoparticles revealed the formation of well-dispersed Au NPs of ca. 2 nm diameter. Moreover, the color change of the Au NP solution as well as UV-vis spectroscopy and TEM measurements have also demonstrated the occurrence of Ostwald ripening of the nanoparticles at low temperature. Further characterization with Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering indicated the formation of a monolayer of lysozyme molecules on the particle surface. FTIR data also indicated the intactness of the protein molecules coated on Au NPs. All the characterization results showed that the monodisperse Au NPs are well-coated directly with lysozyme. Driven by the dipole-dipole attraction, the protein-stabilized Au NPs self-assembled into network structures and nanowires upon aging under ambient temperature. On the basis of their excellent colloidal stability, controlled self-assembly ability, and biocompatible surface, the lysozyme monolayer-stabilized Au NPs hold great promise for being used in nanoscience and biomedical applications.

A large-scale lambda-DNA network on a mica surface was successfully fabricated with a simple method. Silver nanoparticles capped with the cationic surfactant cetyltrimethylammonium bromide (CTAB) were self-assembled onto a two-dimensional DNA network template by electrostatic interaction and formed nanoporous silver films, which can be used as active surface-enhanced raman scattering (SERS) substrates. Two probe molecules, Rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP), were studied on these substrates with very low concentrations, and great enhancement factors for R6G (0.21 x 10(10)-4.09 x 10(11)) and 4-ATP (approximately 1.70 x 10(5)) were observed. It was found that the enhancement ability was affected by the DNA concentration and the electrostatic absorption time of the CTAB-stabilized silver nanoparticles on the DNA strands. These SERS substrates formed by the self-assembly of silver nanoparticles on DNA network also show good stability and reproducibility in our experiments.