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Problem statement: [WO.sub.3] is one of the most interested metal oxides because of its application as catalysts, sensors, electrochromic devices, ceramic, solar cell, pigments and so on. More investigation is needed to find the good and low cost method for preparation of [WO.sub.3] nanoparticles with uniform morphology and narrow distribution using a surfactant mediated method. Approach: In this study, the synthesis of [WO.sub.3] nanoparticles was accomplished using a cationic surfactant (cetyl trimethyl ammonium bromide) as the organic supermolecular template and [WCl.sub.6] and [NH.sub.4]OH as the inorganic precursor and counter ion source, respectively. The effects of reaction temperature and surfactant concentration in particle size of resultant [WO.sub.3] nanoparticles were investigated. Results: The different ranges of particle size and size distribution were obtained using different surfactant concentration and reaction temperature. The [WO.sub.3] particles in the nanometer range (3-15 nm) with uniform morphology and narrow distribution were obtained by optimization of reaction condition. X-ray diffraction, transmission electron microscopy, variable pressure scanning electron microscope, X-ray photoelectron spectroscopy and UV-Vis spectroscopy were used to characterize the final products. The nanomaterials [WO.sub.3] showed different pattern in UV-Vis spectroscopy compare to the bulk [WO.sub.3]. Conclusion: A relatively simple and effective procedure for synthesis of [WO.sub.3] nanoparticles with mean size below 10 nm, narrow size distribution and high monodispersity using CTAB supramolecular template had been developed and optimized. Key words: Nanostructures, [WO.sub.3], chemical synthesis, optical properties, INTRODUCTION One of the most interesting properties of some materials is their ability in spontaneous assembling into higher order structures with distinctive chemical and physical properties. Cationic supermolecular surfactant Cetyl [...]

Nanoparticles (NPs) decorated with ligands combining photoswitchable dipoles and covalent cross-linkers can be assembled by light into organized, three-dimensional suprastructures of various types and sizes. NPs covered with only few photoactive ligands form metastable crystals that can be assembled and disassembled 'on demand' by using light of different wavelengths. For higher surface concentrations, self-assembly is irreversible, and the NPs organize into permanently cross-linked structures including robust supracrystals and plastic spherical aggregates. azobenzene L colloids I crystallization / dynamic / photoswitchable

The role of NaOH concentration on the oriented attachment growth kinetics was studied by investigating the crystal growth kinetics of ZnS nanoparticles coarsened less than 100 degree Celsius with NaOH concentration from 2 to 8 M. The findings suggest that the concentration of solute is very important for enhancing the oriented attachment growth rate and achieve exclusively oriented attachment growth of nanoparticles at a large size scale.

Simple techniques involving electro- and electroless deposition from a 0.05 mM Au[Cl.sub.3] and 0.1 M NaCl[O.sub.4] solution were employed to grow dome-shaped gold nanoparticles with an average diameter of 10.5 nm on H-terminated Si(100) substrates. The results show that the deposited Au nanoparticles belong to the fcc phase with the relative intensity of the (220) plane for Au nanoparticles obtained by electroless deposition found to be notably larger than that by electrodeposition.

Density functional theory calculations were used to study the morphology of a [Pt.sub.37] nanoparticle supported on carbon with and without hydrogen passivation. It was shown that hydrogen passivation stabilize the truncated structure of [Pt.sub.37] by removing an electronically induced shear instability of Pt(001) facets.

The surface chemistry of pristine, 6-nm silicon nanoparticles is investigated by using Fourier transform infrared spectroscopy (FTIR) and static time-of-flight secondary ion mass spectroscopy (ToF-SIMS). ToF-SIMS measurements have suggested that hydrogen has desorbed from the particles surfaces over the same temperature range that the particles shrink.

The structure and reactivity of Fe/iron oxide core-shell nanoparticles (Fe-Ox) that are coated with dopamine are reported. The results have shown that the reactivity between [Fe.sup.3+] and dopamine quickly facilitates the degradation of the nanoparticles.

A bivariale population balance equation (PBE) model is developed and combined with new Monte Carlo (MC) simulations to study and predict the nanoparticle size distribution synthesized by mixing two water-in-oil reactive microemulsions solutions. The analysis proves to be extremely helpful in observing the mean aggregate number (MAN), as well as the size of the CdS nanoparticles and shows that MAN largely varies with the concentration and the microemulsion drop size of the nanoparticles.

A study of Cu deposition on the surface of spherical Si[O.sub.2] nanoparticles is conducted to achieve the hybrid structure of Cu-Si[O.sub.2] nanocomposite. Excellent antibacterial ability is shown by the homogeneously formed Cu nanoparticles on the surface of Si[O.sub.2] nanoparticles without aggregation of Cu nanoparticles.

Different characterization techniques are used investigate the [Al.sub.2][O.sub.3]-supported Au catalysts in order to elucidate the geometric structure and the electronic states of the gold particles dependent on the used precipitation agent NaOH or urea. The influence of the precipitation agent on the deposition of gold nanoparticles on oxidic nanoparticles is discussed.

A fast and simple method is proposed for producing homogeneous silvered nanostructures on a glass surface as potential substrates for fluorescence enhancement assays. It is demonstrated that the Au core-Ag shell nanostructures on glass surfaces are promising substrates for fluorescence enhancement with outstanding macroscopic homogeneity.

A deep UV-Raman and FTIR spectroscopy is used to investigate the vibrational spectra of platinum nanoparticles capped with poly(N-vinylpyrrolidone) (PVP) and compared with pure PVP. It is concluded that under oxidizing conditions, both PVP/ Pt and PVP degrade to form amorphous carbon.

The differences between the decanethiolate gold nanoparticles synthesized by two different routes, one-phase and two-phase methods are investigated. It is revealed that by transmission electron microscopy (TEM) and X-ray reflectivity (XR), the close-packed monolayer of the two-phase particles collapsed and folded into multilayer films upon further compression.

The catalysts with various gold loadings are prepared by the modified impregnation procedure and the nature of the supported gold phase is characterized. The Au/Ti[O.sub.2] catalysts prepared by this modified procedure of impregnation are almost as active as those prepared by deposition-precipitation with urea in the CO oxidation reaction performed at room temperature.

The geometrical dependence of the localized surface plasmon resonant extinction spectrum of gold nanorods is examined to monitor their synthesis kinetics. The rate dependence on nanorod size has not corresponded to any simple reaction-limited or diffusion-limited growth mechanisms.

The near-field coupling interactions between surface plasmon modes of neighboring metal nanoparticles (NPs) are examined in thin films of oligothiphene-linked Au NPs. The surface plasmon resonance (SPR) coupling between NPs is found to be highly dependent on the dielectric constant of the medium that the films are exposed to, where a higher dielectric medium leads to weaker coupling.

Synthesis of four different sizes of citrate-protected silver nanoplates with the corresponding in-plane dipole resonance band at 530, 619, 778, and 858 nm, respectively is performed for surface-enhanced Raman scattering (SERS) study. Results reveal that a market red shift of the in-plane dipole resonance of silver nanoplates is observed, whereas their other resonance modes only have small alterations in the site or intensity during the aggregation process.

A reproducible synthesis of platinum nanoparticles (Pt NPs) stabilized with a water-soluble phosphine was developed by ligand exchange with preformed gylcol-stabilized platinum nanoparticles. Complete reduction of oxygen by four electrons is achieved with 4 layers of TPPTP-Pt NPs and a total Pt loading of 5.6 mug/[cm.sup.2].

Synthesis of active fold and palladium nanoparticles supported on MgO nanocubes and ZnO nanobelts and transition-metal-containing MgO nanobelts is presented by combining evaporation and deposition-precipitation techniques. The high activity and stability of the Au/CeO2 and Pd/CeO2 nanoparticle catalysts deposited on the MgO cubes are remarkable implying that a variety of efficient catalysts could be designed and tested using this approach.

A study synthesizes the model system of the hydrotreating catalyst consisting of Mo[S.sub.2] nanoclusters supported on a graphite surface in order to resolve some fundamental questions related to the atomic-scale structure and morphology of the active clusters, particularly the effect of a substrate used in some types of hydrotreating catalysts. The synthesized Mo[S.sub.2] nanoclusters are found to display a very temperature-dependent morphology, since clusters prepared at 1000 K grow as single-layer clusters, whereas clusters prepared at 1200 K exclusively grow as stacked multilayer clusters.

A study demonstrates that nanoparticles of trans-beta-carotene are accessible using spinning disk processing (SDP), by varying the reaction conditions and the choice of surfactant, macrocyclic amphiphiles, sulfonato-calix[4,5,6,8] arenes, and alpha-beta-cyclodextrins. SDP ensures rapid mixing and fast kinetics, and nanoparticles of the carotene formed in the presence of the calixarenes are stable with respect to extraction of the carotene into an organic solvent, unlike in the presence of the cyclodextrins.

The structural characteristics and adsorption behavior of 4,4'-thiobenzenethiol (TBBT) self-assembled monolayers (SAMs) on Au is investigated by surface enhanced Raman scattering (SERS), electrochemical cyclic voltammetry (CV), ac impedance spectroscopy (EIS), and atomic force microscopy (AFM). A scanning electron microscopic image of Ag nanoparticles on TBBT/Au and the Raman spectrum of TBBT in smooth macroscopic Au/TBBT SAMs/Ag nanoparticle sandwich structure indicate that metal nanoparticles could be adsorbed on TBBT SAMs effectively through covalent linkage.

The formation of silver nanoparficles by chemical reduction of [Ag.sup.+]-loaded Nation- 1 17 membrane with NaB[H.sub.4] was studied using radioactivity tagged ions. The counterion-exchange method ([Ag.sup.+.sub.(m)]) [??] [Na.sup.+.sub.(s)]) was used to obtain a membrane sample with a varying proportion of [Ag.sup.+] ions. The X-ray elemental mapping across the thickness of the membrane by energy-dispersive X-ray spectrometer attached to the environmental scanning electron microscope (ESEM/EDAX) indicated that [Na.sup.+] and [Ag.sup.+] were uniformly distributed in the membrane samples before reduction. The average size of nanoparficles formed after reduction was found to be 15 [+ or -] 3 nm, irrespective of the concentration of silver ions present in the membrane before reduction. Energy-dispersive X-ray fluorescence (EDXRF) analyses of the membrane samples, carried out before and after reduction, indicated that the Ag concentration on the membrane surface was considerably increased after reduction. EDXRF measurements of the membrane samples, obtained from reduction carried out in a dead end cell, indicated that Ag nanoparficles were formed only on the membrane surface exposed to NaBH4 solution. Reduction carried out with NaB[H.sub.4] tagged with [sup.22]Na showed that the formation of Ag nanoparticles involved exchange of [Ag.sup.+] ions from ion-exchange sites in the interior of the membrane with [Na.sup.+] ions, followed by reduction of [Ag.sup.+] ions with B[H.sub.4.sup.-] ions at the surface of membrane. The study of self-diffusion of water, [Na.sup.+], and [Cs.sup.+] ions in the membrane loaded with Ag nanoparticles indicated that formation of Ag nanoparticles did not affect the diffusional transport properties of the membrane. The ion-exchange capacity and water uptake capacity were also not affected by the formation of Ag nanoparticles in the membrane. The spatial distribution of Ag nanoparficles across the thickness of the membrane obtained by ESEM/EDAX showed that Ag nanoparticles were confined to a few-micrometer surface layer of the membrane. Based on these observations, an attempt has been made to explain the mechanism of the formation of Ag nanoparticles in the membrane.

The formation and the structural properties of 'supermicellar' aggregates made from mineral nanoparticles and polyelectrolyte-neutral block copolymers in aqueous solutions are reported. It was found that the hybrid aggregates have typical sizes in the range of 100 nm and exhibit a remarkable colloidal stability with respect to ionic strength and concentration variations.

Metal catalyzed, CVD-grown silicon nanowires decorated by chemical assembly of closely spaced Ag nanocrystals were modified with the well-known 'silver mirror' reaction and investigated as substrates for surface-enhanced Raman (SERS) and hyper-Raman (SEHRS) spectroscopy. Four chromophores were examined: Rhodamine 6G, crystal violet, a cyanine dye, and a cationic donor-acceptor substituted stilbene. After soaking the substrates overnight in [10.sup.-4] M aqueous chromophore solutions, all four chromophores gave good-quality SERS spectra in [less than or equal to] 60 s using < 1 [micro]W of 458-nm cw laser power, and SEHRS spectra are obtained in [less than or equal to] 120 s using < 1 mW of mode-locked 916-nm laser power. Results from this substrate are compared with those on colloidal silver nanoparticles deposited as a film, as well as surfaces grown by the silver mirror reaction.

Novel silver nanoparticles/polyaniline composites are obtained through a two-phase water/toluene interfacial reaction. The conductivity and current-voltage characteristics of nanocomposites have indicated that different properties result from the different structures in which the nanocomposites are formed.

The controlled decomposition of [Pt.sub.2][(dba).sub.3] (dba = dibenzylideneacetone) dispersed in 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.B[F.sub.4]) and hexafluorophosphate (BMI.P[F.sub.6]) ionic liquids in the presence of cyclohexene by molecular hydrogen have produced Pt(0) nanoparticles. The SAXS analysis has shown the formation of a semi-organized ionic liquid layer surrounding the metal particles with an extended molecular length of around 2.8 nm in BMI.B[F.sub.4] and 3.3 nm in BMI.P[F.sub.6].

Effect of substrate on surface-enhanced Raman scattering of molecules adsorbed on immobilized silver nanoparticles was studied by assembling Ag nanoparticles on polyvinylpyridine (PVP) derivatized glass slides. It was shown that the positive charge of the PVP layer could alter the charge distribution in the immobilized nanoparticles and induce the formation of the dipole in the nanoparticles, leading to less charge transfer from the metal to the adsorbed molecules.

An ultrafast Au/Ti[O.sub.2] photosynthetic reduction of elemental sulfur [[S.sub.8]] to [H.sub.2]S in ethanol solutions is reported. A kinetic analysis has shown that the increase in the rate of reaction with decreasing nanoparticles (d) results from the improvement of the charge separation efficiency.

A dendron-like nanostructure of silver is grown in solution by using a water-soluble tetrapeptide Tyr-Aib-Tyr-Val (Aib, alpha-amino isobutyric acid), silver nitrate and methonal. The optical absorption spectra is analyzed by Mie scattering theory, which shows that there is a metal-nonmetal transition in silver particles having diameters less than ~2.0 nm.

Particulates play an important role in influencing the interfacial adhesion by changing the average separation of the contacting rough surfaces. The high temperature annealing in the fabrication process has allowed residual carbon in the tetraethylorthosilicate (TEOS) sacrificial oxide layer to migrate to the polysilicond surface and form the SiC particles.

The competition between recombination of a radical pair and radical attack on targets such as macromolecules or nanoparticles in solution is described along with the effect of the initial spatial correlation of the radicals on the kinetics of attack on the targets. The results include the simple modification of the Smoluchowski rate coefficient for scavenging and the probability of multiple hits on the same target.

The results of nanoparticle-catalyzed synthesis of a variety of silica nanocoils (SiNCs) under similar growth conditions to those of making regular straight silica/silicon nanowires(SiNWs) are reported. The results suggest that the same nanoparticle could be responsible for the growth of straight SiNWs and SiNCs at two different temperatures.

Preparation of shape-controlled metastable gama-MnS semiconductor nanocrystals was achieved on a large scale through a simple solvothermal method in the presence of PVP. The optical absorption measurement reveals that these novel architectures exhibit remarkable shift of absorption peak during the course of structural compaction and grain growth.

A sonochemical method for the preparation of a colloidal solution of iron oxide in decalin by the use of oleic acid as a long-chain stabilizer is described. Replacing long-chain PVA by SDS resulted in the disappearance of dendrite fractal structures which is due to the extensive magnetic interactions between the particles.

An enhancement in the fluorescent signal of the carbocyanine dye Cy5 by using an engineered virus as a scaffold to attach >40 Cy5 reporter molecules at fixed location on the viral capsid are presented. When compared with the most often used detection methods in a microarray based genotyping assay for vibrio cholerae O139, these viral nanoparticles markedly increased assay sensitivity, thus demonstrating their applicability for existing DNA microarray protocols.

A study uses ultra-violet (UV)-visible extinction spectroscopy and femtosecond pump-probe transient absorption spectroscopy to investigate the effect of femtosecond laser heating on gold nanoparticles attached to DNA ligands through thiol groups. Results show that femtosecond pulse excitation of the deoxyribonucleic acid (DNA)-modified nanoparticles leads to desorption of the thiolated DNA strands from the nanoparticle surface by the dissociation of the gold-sulfur bond.

Tunable polyelectrolyte multilayer capsule reactors (PEMCRs) containing two different functional groups are prepared, which could be used to synthesize two types of nanoparticles simultaneously and to control the composition of two types of nanoparticles within the shell of PEMCs. The advantage of this approach is that PEMC nanoreactor chemistry can be extended to the tunable synthesis of two types of nanoparticles within a single component system that possesses more than a single function.

The nonlinear Rayleigh-Gans-Debye theory is described and used to probe molecules adsorbed on nanometer size colloidal particles. It is observed that optical second-harmonic generation from molecules adsorbed occurs at angles as large as 90 degree away from the fundamental beam direction.

A report that monodisperse [Au.sub.11] clusters and bimodal distributions of [Au.sub.8] and [Au.sub.10] could be produced by reducing a Au(I) precursor in the presence of bidentate phosphine ligands is presented. Results reveal that the cluster size could be varied by simply varying the length of the spacer separating the P atoms in the ligand and that certain diphosphine ligands could be extremely size-selective.

Hollow gold nanospheres (HGNs) were utilized to study the ability to tailor charge oscillations of HGN aggregates by systematic variation of particle aspect ratio, interparticle gap, and nanosphere inner surface spatial separation. The findings for the inner HGN surface in the interparticle coupling mechanism and the structure-dependent SPR properties might be significant for applications derived from the plasmonic nanostructure platform.

Multifunctional polymer nanoparticles approximately the size of a large protein is purified by using an affinity chromatography strategy. The purified particles have shown much stronger affinity and a narrower affinity distribution than the average of particles before purification at room temperature but can release the peptide by changing the temperature.

Several analyses are conducted to explain the significance of multivalency in the various nanoparticles that are used for targeting the transferring receptor. The importance of such systems in treating diseases like cancer is also analyzed.

The article presents a new approach, which employs the laser ablation technique for the synthesis of the hollow vanadium pentoxide, [V.sub.2][O.sub.5] nanoparticles. The association existing between these nanoparticles and fullerene-like analogues is also demonstrated.

The effect of short RNA interference (SiRNA) coupling strategies is evaluated by using a model nanoparticle system with varying conjunction schemes. The studies have shown that the accessibility of the siRNA linked to the nanoparticle and the lability of the cross-linker are critical for efficient gene knockdown.

The article discusses the development of a new strategy, which can be employed for the rational synthesis of different heterostructured nanoparticles. The morphology control mechanism for the nanoparticles is shown to be extremely beneficial in making them fit for catalytic and functional applications.