Synthesis of a nanocomposite composed of reduced graphene oxide and gold nanoparticles.

We report a seeded-growth process that results in the adhesion of size-controlled gold (Au) nanoparticles (NPs) to the surface of reduced graphene oxide (rGO), leading to the formation of rGO-Au nanocomposites. The synthesis approach involves the utilization of Au molecular precursors (i.e.

Structure and performance of dielectric films based on self-assembled nanocrystals with a high dielectric constant.

Self-assembled films built from nanoparticles with a high dielectric constant are attractive as a foundation for new dielectric media with increased efficiency and range of operation, due to the ability to exploit nanofabrication techniques and emergent electrical properties originating from the nanoscale. However, because the building block is a discrete one-dimensional unit, it becomes a challenge to capture potential enhancements in dielectric performance in two or three dimensions, frequently due to surface effects or the presence of discontinuities. This is a recurring theme in nanoparticle film technology when applied to the realm of thin film semiconductor and device electronics.

Synthesis of hollow ellipsoidal silica nanostructures using a wet-chemical etching approach.

We have utilized wet-chemical etching of ellipsoidal silica nanoparticles (ESNs) to form silica nanoshells of a range of elliptical morphologies, with the thicknesses of the ellipsoidal silica nanoshells (ESSs) controlled through variation of synthesis conditions. A mechanism has been proposed to explain how the nanoshells are formed, and we demonstrate that the porosity of the silica ellipsoid plays a role in generating silica shells. Our self-templated, wet-etching approach is an attractive alternate procedure to the approaches presently in existence for the following reasons: (i) it is a facile, one-step process that directly produces ellipsoidal silica nanoshells, while overcoming barriers (such as requirement of removing a solid-core template seed) utilized in many reported chemical etching studies; (ii) it results in ellipsoidal silica nanostructures with dimension less than 100 nm; (iii) with an appropriate etchant, the roughness of the silica shells can be well-controlled; and (iv) it results in tunable, uniform size particles with controllable shell thicknesses.

Formation of Graphene Oxide Nanocomposites from Carbon Dioxide Using Ammonia Borane.

To efficiently recycle CO(2) to economically viable products such as liquid fuels and carbon nanomaterials, the reactivity of CO(2) is required to be fully understood. We have investigated the reaction of CO(2) with ammonia borane (AB), both molecules being able to function as either an acid or a base, to obtain more insights into the amphoteric activity of CO(2). In the present work, we demonstrate that CO(2) can be converted to graphene oxide (GO) using AB at moderate conditions.

A Study of the Effect of Heat-Treatment on the Morphology of Nafion Ionomer Dispersion for Use in the Passive Direct Methanol Fuel Cell (DMFC).

Aggregation in heat-treated Nafion ionomer dispersion and 117 membrane are investigated by 1H and 19F Nuclear Magnetic Resonance (NMR) spectra, spin-lattice relaxation time, and self-diffusion coefficient measurements. Results demonstrate that heat-treatment affects the average Nafion particle size in aqueous dispersions. Measurements on heat-treated Nafion 117 membrane show changes in the 1H isotropic chemical shift and no significant changes in ionic conductivity.

Template-free synthesis of silica ellipsoids.

We have created ellipsoidal or spherical morphologies of silica particles in a template-free scheme that involves controlling surface tension forces through selected volume ratios of a water/oil micellar system.

Density functional theory and Raman spectroscopy applied to structure and vibrational mode analysis of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachloro- benzimidazolocarbocyanine iodide and its aggregate.

We have measured electronic and Raman scattering spectra of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachloro-benzimidazolocarbocyanine iodide (TTBC) in various environments, and we have calculated the ground state geometric and spectroscopic properties of the TTBC cation in the gas and solution phases (e.g., bond distances, bond angles, charge distributions, and Raman vibrational frequencies) using density functional theory.

A covalently linked phenanthridine-ruthenium(II) complex as a RNA probe.

A phenanthridine derivative covalently linked to a ruthenium complex yields an imaging probe whose fluorescence intensity and lifetime change substantially in the presence of RNA.

Enhanced dehydrogenation of LiBH4 catalyzed by carbon-supported Pt nanoparticles.

The catalytic dehydrogenation of LiBH(4) doped with exceptionally low quantities of carbon-supported Pt nanoparticles can be improved significantly, and smaller Pt nanoparticles result in greater enhanced catalytic dehydrogenation of LiBH(4) than do larger Pt nanoparticles.

Two color RNA intercalating probe for cell imaging applications.

Here we report on a phenanthridine derivative which has a covalently linked fluorescein molecule in order to increase the light absorption and hence fluorescence signal intensity when bound to duplex RNA. Steady-state fluorescence shows that the energy transfer efficiency from the fluorescein to the phenanthridine fluorophore is approximately 77%, which results in the probe being over 5x brighter than other phenanthridine derivatives when bound to RNA. Due to the relatively long lifetime (approximately 20 ns) of the probe, time-resolved fluorescence is used to increase the signal to background ratio in cell growth medium from 7 (steady-state value) to over 40.

Design and characterization of two-dye and three-dye binary fluorescent probes for mRNA detection.

We report the design, synthesis and characterization of binary oligonucleotide probes for mRNA detection. The probes were designed to avoid common problems found in standard binary probes such as direct excitation of the acceptor fluorophore and overlap between the donor and acceptor emission spectra. Two different probes were constructed that contained an array of either two or three dyes and that were characterized using steady-state fluorescence spectroscopy, time-resolved fluorescence spectroscopy and fluorescence depolarization measurements.

Combinatorial fluorescence energy transfer molecular beacons for probing nucleic acid sequences.

We report the design, synthesis, and characterization of molecular beacons (MB) consisting of three distinct fluorophores, 6-carboxyfluorescein (Fam), N,N,N',N'-tetramethyl-6-carboxyrhodamine (Tam), and Cyanine-5 (Cy5). The primary light absorber/energy donor (Fam) is located on one terminus of the MB, whereas the primary energy acceptor/secondary donor (Tam) and secondary acceptor (Cy5) are located at the other terminus of the MB. In the absence of target DNA or RNA, the MB exists in the stem-closed form.

Optical spectra of a novel polyoxometalate occluded within modified MCM-41.

The novel polyoxometalate ([(Eu2PW10O38)4(W3O8(H2O)2(OH)4)]22-), also referred to herein as Eu8P4W43, has been immobilized inside the channels of MCM-41 mesoporous molecular sieve material by means of the incipient wetness method. For proper host-guest interaction, amine groups were introduced into the system as a result of an aminosilylation procedure. A stable and integrated Eu8P4W43 polyoxometalate was shown to be formed inside the channels of the modified MCM-41.

Spectroscopic investigation of a FRET molecular beacon containing two fluorophores for probing DNA/RNA sequences.

We report the design, synthesis, and characterization of a molecular beacon (MB) consisting of two fluorescent dyes (Alexa 488 and RedX) for DNA and RNA analysis. In the absence of the target DNA or RNA the MB is in its stem-closed form and shows efficient energy transfer from the donor (Alexa) to the acceptor (RedX), generating mostly fluorescence from RedX. In the presence of the complementary target DNA the MB opened efficiently, hybridizes with the target DNA, and energy transfer is blocked in the stem-open form.

Diameter-selective dispersion of single-walled carbon nanotubes using a water-soluble, biocompatible polymer.

One-step diameter-selective dispersion of HiPco single-walled carbon nanotubes has been accomplished through noncovalent complexation of the nanotubes with a water-soluble, biocompatible polymer chitosan at room temperature.

Microwave absorption by nanostructural ferric oxide encapsulated within MCM-41.

A new functional material with nonzero microwave absorption ability at zero applied magnetic field results from loading MCM-41 to a high percentage by weight with ferric oxide.