Nanoparticles composed of magnetic cores with continuous Au shell layers simultaneously possess both magnetic and plasmonic properties. Faceted and tetracubic nanocrystals consisting of wüstite with magnetite-rich corners and edges retain magnetic properties when coated with an Au shell layer, with the composite nanostructures showing ferrimagnetic behavior. The plasmonic properties are profoundly influenced by the high dielectric constant of the mixed-iron-oxide nanocrystalline core. A comprehensive theoretical analysis that examines the geometric plasmon tunability over a range of core permittivities enables us to identify the dielectric properties of the mixed-oxide magnetic core directly from the plasmonic behavior of the core-shell nanoparticle.

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Single-source molecular precursors were found to produce iron phosphide materials. In a surfactant system of trioctylamine and oleic acid, H2Fe3(CO)9PtBu reacted to form Fe4(CO)12(PtBu)2, which decomposed to give Fe2P nanorods and "bundles." Control of the morphology obtained was possible by varying the surfactant system; addition of increasing amounts of oleic acid resulted in crystal splitting, while the addition of microliter amounts of an alkane enhanced the crystal splitting to give sheaflike structures. The different morphologies seen were attributed to imperfect crystal growth mechanisms.

We present a carbon paste electrode (CPE) modified using the electron mediator bis(1,10-phenanthroline-5,6-dione) (2,2′-bipyridine)ruthenium(II) ([Ru(phend) 2+ exhibited luminescence even at low concentration. Modified CPEs were constructed and analyzed using cyclic voltammetry. The intercalated mediator remained electroactive within the layers (E°′ = −38.5 mV vs. Ag/AgCl, 3.5 M NaCl) and electrocatalysis of NADH oxidation was observed. The kinetics of the modified CPE shows a Michaelis -Menten behavior. This CPE was used for the oxidation of NADH in the presence of Bakers' yeast alcohol dehydrogenase. A calibration plot for ethanol is presented.

The conversion of hexagonal-, square-, and cross-shaped MnO nanoparticles into mixed MnO-Mn 3 O 4 nanoparticles occurs with retention of the nanoparticle shape. Upon aging, extra diffraction spots appear in the TEM analyses of both hexagonal-and cross-shaped nanoparticles (NPs). These extra diffraction spots can be assigned to the spinel form of Mn 3 O 4 (s-Mn 3 O 4 ) and exhibit moiré interference patterns arising from the presence of two closely aligned, crystallographically similar phases. Examination of a variety of reaction conditions showed that the transformation of MnO into MnO/Mn 3 O 4 occurred while the particles are suspended in hexane at ambient temperature, by refluxing in hexadecane for 36 h, by heating to 200°C in air, and by irradiating the NPs with a Raman laser beam. The crystal phase development and shape retention can be observed by using transmission electron microscopy (TEM). Single-crystal and polycrystalline selected area electron diffraction (SAED) patterns and dark-field TEM images confirm the coexistence of both MnO and s-Mn 3 O 4 phases. Evaluation of the polycrystalline SAED patterns after irradiation in the Raman spectrometer indicated the presence of rings assignable to the tetragonal phase of Mn 3 O 4 (t-Mn 3 O 4 ) as well as MnO and s-Mn 3 O 4 . The growth of the tetragonal phase by laser heating in the Raman experiment was confirmed by powder X-ray diffraction.

We report the functionalization of individual ultra-short (20–80 nm lengths) single-walled carbon nanotubes (US-tubes) via in situ Bingel cyclopropanation. Upon chemical reduction (K°/THF) of bundled US-tubes, the bundling forces are electrostatically overcome to yield single, negatively charged US-tubes in solution. These single US-tubes can then be functionalized with malonic acid bis-(3-tert-butoxycarbonylaminopropyl) ester using Bingel chemistry (CBr4/DBU) to yield 4–5 adducts nm−1, as determined by x-ray photoelectron spectroscopy (XPS). The derivatized US-tubes remain as individuals after functionalization and charge quenching. Thermogravimetric analysis (TGA) and solid-state NMR spectroscopy confirmed covalent attachment of the adducts and indicated tight wrapping of the adduct arms about the US-tubes. The resulting debundled and derivatized US-tubes serve as a prototype single-molecule-like ‘capsule’ for the containment and delivery of medically-useful payloads.

New nanoparticle shapes of iron oxide (FexOFe3O4, where 0.8 < x < 1) and iron‐manganese oxide (Fe1–yMnyOFe3–zMnzO4, where 0 < y < 1, and 0 < z < 3) were synthesized by decomposition of the corresponding metal formates in tri‐n‐octylamine/oleic acid mixtures at elevated temperatures (ca. 370 °C), under an inert atmosphere. Details of the syntheses leading to the various shapes of nanoparticles are provided as a function of the reactions parameters, that is, precursor type and concentration, surfactant concentration, water concentration, reaction time, and temperature. Different electron microscopy techniques were used to characterize the crystal phases and the novel shapes of these nanostructures. Nanoparticles of FexOFe3O4 were produced with different shapes, that is spheres, hexagons, and cubes, depending on the reaction conditions. By tuning the conditions, iron oxide nanocubes with concave faces were produced exclusively. Electron and X‐ray diffraction data reveal these nanocubes to be single‐crystal FexO (wüstite) with small amounts of Fe3O4 (magnetite). For the mixed metal system, solid solutions of Fe1–yMnyO with very small amounts of Fe3–zMnzO4 were observed, in which the produced oxide had a larger Fe:Mn ratio than present in the starting reagents. Adjusting the iron to manganese ratio in the mixed‐metal nanoparticles resulted in different shapes. Nanoparticles with ca. 1:1 (Fe:Mn) ratios displayed a ‘dog‐bone‐like’ morphology, which can be considered a shape in between a pure FexOFe3O4 nanocube and the rod‐like nanostructures previously reported for the manganese oxide system. In general, higher Fe:Mn ratios (e.g., 9:1) in the product resulted in nanostructures with cubic shapes, while lower Fe:Mn values (e.g., 2:8) resulted in long (ca. 200 nm) rod‐like nanostructures with flared ends. All of the nanostructures reported here exhibit internal structures that suggest a growth mechanism with etching on negatively curved rough crystal faces. Oxidation of the nanoparticles occurred with retention of their original shape.

This communication reports the development of a TiO 2 -streptavidin nanoconjugate as a new biological label for X-ray bio-imaging applications; this new probe, used in conjunction with the nanogold probe, will make it possible to obtain quantitative, high-resolution information about the location of proteins using X-ray microscopy.Soft X-ray tomography generates 3D images of whole, hydrated cells at a resolution better than 50 nm. 1,2 High-contrast images of cellular structures are obtained because organic material absorbs roughly an order of magnitude more than water at this energy (517 eV). Minimal cell processing is required, as cells need only be frozen, and data collection is rapid (3-5 min per tomographic data set). X-Ray tomography is, therefore, an appealing imaging technique for those experiments that require better resolution than is possible with light microscopy. With light microscopy, fluorescent tags are routinely used to label molecules. For X-ray microscopy, we need probes that use the inherent X-ray properties and can specifically label proteins within the cellular environment. Since X-ray transmission is sensitive to absorbance and density differences in the specimen, as is transmission electron microscopy (TEM), probes used in TEM should also work for X-ray microscopy. Current approaches for localization used with TEM include labeling with Au nanoparticles or photooxidation of diaminobenzidene (DAB). Similar approaches have proven viable for soft X-ray microscopy, as demonstrated by the use of gold nanoparticles conjugated to antibodies to localize proteins in whole cells. 3Co-localization studies with light microscopy are routinely done using probes that fluoresce at two different wavelengths. For similar studies with X-ray microscopy, we need two tags that can be unambiguously identified, which means the probes need to have different absorption properties, such as an X-ray edge absorption. The dense DAB reaction product and the Au nanoparticles are directly visible in the soft X-ray microscope. However, the contrast mechanism of both probes is based on absorption density of the matter. No X-ray † Electronic supplementary information (ESI) edge absorption is available for either of them within the range of the operation energy. Therefore, indistinguishable X-ray absorption properties of these probes negate the possibility to utilize them in double labeling experiments with soft X-ray microscopy. With the rapidly expanding field of nanoscience in biology, especially the successful application of semiconductor nanocrystals in biological imaging, 4-7 additional nanoparticular materials that exhibit strong absorption in the soft X-ray spectrum are being developed. One promising candidate is TiO 2 . TiO 2 nanoparticles have been widely used in other industries due to their photocatalytic activity and UV light absorption properties. 8 They are also highly biocompatible. A recent study demonstrated the use of a TiO 2 -oligonucleotide nanocomposite as a unique light inducible nucleic acid e...