A novel "reactomics" approach for cancer diagnostics.

Non-invasive detection and monitoring of lethal diseases, such as cancer, are considered as effective factors in treatment and survival. We describe a new disease diagnostic approach, denoted "reactomics", based upon reactions between blood sera and an array of vesicles comprising different lipids and polydiacetylene (PDA), a chromatic polymer. We show that reactions between sera and such a lipid/PDA vesicle array produce chromatic patterns which depend both upon the sera composition as well as the specific lipid constituents within the vesicles.

Catalysis in a porous molecular capsule: activation by regulated access to sixty metal centers spanning a truncated icosahedron.

The 30 cationic {Mo(V)2O4(acetate)}(+) units linking 12 negatively charged pentagonal "ligands," {(Mo(VI))Mo(VI)5O21(H2O)6}(6-) of the porous metal-oxide capsule, [{Mo(VI)6O21(H2O)6}12{Mo(V)2O4(acetate)}30](42-) provide active sites for catalytic transformations of organic "guests". This is demonstrated using a well-behaved model reaction, the fully reversible cleavage and formation of methyl tert-butyl ether (MTBE) under mild conditions in water. Five independent lines of evidence demonstrate that reactions of the MTBE guests occur in the ca.

Studying the structural dynamics of bipedal DNA motors with single-molecule fluorescence spectroscopy.

We present a test case example of a detailed single-molecule fluorescence study of one of the most sophisticated and complex DNA devices introduced to date, a recently published autonomous bipedal DNA motor. We used the diffusion-based single-molecule Förster resonance energy transfer technique, coupled to alternating laser excitation (sm-FRET-ALEX), to monitor the motor assembly and operation. The study included verification of the formation of the correct structures, and of the correct motor operation, determination of the formation and stepping reaction yields, and identification of side products.

The interaction between colloids in polar mixtures above Tc.

We calculate the interaction potential between two charged colloids immersed in an aqueous mixture containing salt near or above the critical temperature. We find an attractive interaction far from the coexistence curve due to the combination of preferential solvent adsorption at the colloids' surface and preferential ion solvation. We show that the ion-specific interaction strongly depends on the amount of salt added as well as on the mixture composition.

Nucleation and island growth of alkanethiolate ligand domains on gold nanoparticles.

The metal oxide cluster α-AlW(11)O(39)(9-) (1), readily imaged by cryogenic transmission electron microscopy (cryo-TEM), is used as a diagnostic protecting anion to investigate the self-assembly of alkanethiolate monolayers on electrostatically stabilized gold nanoparticles in water. Monolayers of 1 on 13.8 ± 0.

Synthesis and characterization of hybrid nanostructures.

There has been significant interest in the development of multicomponent nanocrystals formed by the assembly of two or more different materials with control over size, shape, composition, and spatial orientation. In particular, the selective growth of metals on the tips of semiconductor nanorods and wires can act to couple the electrical and optical properties of semiconductors with the unique properties of various metals. Here, we outline our progress on the solution-phase synthesis of metal-semiconductor heterojunctions formed by the growth of Au, Pt, or other binary catalytic metal systems on metal (Cd, Pb, Cu)-chalcogenide nanostructures.

A hybrid biocathode: surface display of O2-reducing enzymes for microbial fuel cell applications.

Laccase and bilirubin oxidase were successfully displayed on the surface of yeast cells. Subsequently, these modified yeast cells were used in the cathode compartment of a microbial fuel cell. The performance of the fuel cells is compared.

Modeling of reflectometric and ellipsometric spectra from the skin in the terahertz and submillimeter waves region.

The human skin is modeled as a stack of homogeneous layers in the terahertz and submillimeter waves regions with some anisotropy due to the helical sweat glands and other elongated entities. A dielectric model for the skin is presented, valid for a wider frequency range (up to the terahertz region) taking into account the dispersive nature of the effective conductivity. Polarized reflectivity and generalized ellipsometric parameters are calculated versus angle and wavelength.

Spatial coherence effect on layer thickness determination in narrowband full-field optical coherence tomography.

Longitudinal spatial coherence (LSC) is determined by the spatial frequency content of an optical beam. The use of lenses with a high numerical aperture (NA) in full-field optical coherence tomography and a narrowband light source makes the LSC length much shorter than the temporal coherence length, hence suggesting that high-resolution 3D images of biological and multilayered samples can be obtained based on the low LSC. A simplified model is derived, supported by experimental results, which describes the expected interference output signal of multilayered samples when high-NA lenses are used together with a narrowband light source.

Vapor-liquid equilibrium in electric field gradients.

We investigate the vapor-liquid coexistence of polar and nonpolar fluids in the presence of a nonuniform electric field. We find that a large enough electric field can nucleate a gas bubble from the liquid phase or a liquid droplet from the vapor phase. The surface tension of the vapor-liquid interface is determined within squared-gradient theory.

Does human skin truly behave as an array of helical antennae in the millimeter and terahertz wave ranges?

The sweat ducts of the human perspiration system are helically shaped tubes, filled with a conductive aqueous solution. Recent studies have claimed that these ducts act as an array of low-Q helical antennae and are dominant in shaping the spectral response in the subterahertz region. Using local homogenization theory for the skin embedded with sweat ducts, we found that multiple interference effects from the skin layers play the major role in determining the skin electromagnetic characteristics in the millimeter and terahertz regions without the need for the assumption of the sweat ducts acting as low-Q helical antennae.

Islands as nanometric probes of strain distribution in heterogeneous surfaces.

Many of the surface phenomena are driven by elastic energy and elastic interactions. Despite the fact that there are many microscopic techniques with nm and atomic resolution, an established technique to study the distribution of strain on the surface is still lacking. We present a study on the Gd(0001)/W(110) system, in which undulations in the Gd layer are detected by STM.

Stability of binary mixtures in electric field gradients.

We consider the influence of electric field gradients on the phase behavior of nonpolar binary mixtures. Small fields give rise to smooth composition profiles, whereas large enough fields lead to a phase-separation transition. The critical field for demixing as well as the equilibrium phase-separation interface are given as a function of the various system parameters.

Shear-induced ordering of micellar arrays in the presence of single-walled carbon nanotubes.

Single-walled carbon nanotubes were found to induce elongation and alignment of surfactant micelles in thin films under the action of shear, leading to the formation of ordered arrays over micron lengths.

Aggregation and self-assembly of amphiphilic block copolymers in aqueous dispersions of carbon nanotubes.

The self-assembly (SA) of amphiphilic block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) was investigated in dispersions of single-walled and multiwalled carbon nanotubes (SWNT and MWNT, respectively) as a function of temperature. Differential scanning calorimetry (DSC) was used for characterization of the thermal behavior of the combined polymers-nanostructures system, and spin-probe electron paramagnetic resonance (EPR) was employed for probing the local dynamic and polarity of the polymer chains in the presence of nanostructures. It was found that SWNT and MWNT modify the temperature, enthalpy, and dynamic behavior of polymer SA.