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Symmetrical protein cages have evolved to fulfil diverse roles in nature, including compartmentalization and cargo delivery.sup.1, and have inspired synthetic biologists to create novel protein assemblies via the precise manipulation of protein-protein interfaces. Despite the impressive array of protein cages produced in the laboratory, the design of inducible assemblies remains challenging.sup.2,3. Here we demonstrate an ultra-stable artificial protein cage, the assembly and disassembly of which can be controlled by metal coordination at the protein-protein interfaces. The addition of a gold (i)-triphenylphosphine compound to a cysteine-substituted, 11-mer protein ring triggers supramolecular self-assembly, which generates monodisperse cage structures with masses greater than 2 MDa. The geometry of these structures is based on the Archimedean snub cube and is, to our knowledge, unprecedented. Cryo-electron microscopy confirms that the assemblies are held together by 120 S-Au.sup.i-S staples between the protein oligomers, and exist in two chiral forms. The cage shows extreme chemical and thermal stability, yet it readily disassembles upon exposure to reducing agents. As well as gold, mercury(ii) is also found to enable formation of the protein cage. This work establishes an approach for linking protein components into robust, higher-order structures, and expands the design space available for supramolecular assemblies to include previously unexplored geometries. An artificial protein cage is readily assembled by metal ion coordination and disassembled by reducing agents, and displays excellent chemical and thermal stability., Author(s): Ali D. Malay [sup.1] [sup.14] , Naoyuki Miyazaki [sup.2] , Artur Biela [sup.3] [sup.4] , Soumyananda Chakraborti [sup.3] , Karolina Majsterkiewicz [sup.3] [sup.5] , Izabela Stupka [sup.3] [sup.5] , [...]

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 [...]

The molecular ion of the nanoparticle [Au.sub.25][([SCH.sub.2][CH.sub.2]Ph).sub.18 ([A.sub.25][(SR).sub.18]) is observed at 7394 Da in fast atom bombardment (FAB, Xe atoms) ionization mass spectrometry using a 3-nitrobenzyl alcohol matrix. A distinctive pattern of positive fragment ions is evident in the mass interval 5225-7394 Da, where peaks are seen for successive mass losses equivalent to [R.sub.2]S entities. Because the [Au.sub.25][([SCH.sub.2][CH.sub.2]Ph).sub.18] nanoparticle structure is crystallographically known to consist of a centered [Au.sub.13] icosahedral core surrounded by six [Au.sub.2][(SR).sub.3] semirings, the [R.sub.2]S loses are proposed to represent serial rearrangements and decompositions of the semiring structures. Mass losses equivalent to [R.sub.2][S.sub.2] and [R.sub.2] entities also appear at the lower end of this mass interval. The most intense spectral peak, at m/z = 5246 Da, is assigned to the fragment [Au.sub.25][S.sub.10], from which all of the [CH.sub.2][CH.sub.2]Ph organic units have been cleaved but from which no gold atoms have been lost. A different pattern of fragmentation is observed at lower masses, producing ions corresponding to serial losses of one gold atom and varied numbers of sulfur atoms, which continues down to a [Au.sub.9][S.sub.2] fragment. FAB mass spectra of the Au nanoparticle are much easier to interpret than laser desorption/ionization spectra, but they show more extensive fragmentation than do electrospray and low laser pulse intensity MALDI spectra. The loss of [R.sub.2]S fragmentation in FAB is distinctive and unlike that seen in the other ionization modes. The FAB spectrum for the nanoparticle [Au.sub.25][(S[([CH.sub.2]).sub.9][CH.sub.3]).sub.18] is also reported; its fragmentation parallels that for [Au.sub.25][([SCH.sub.2]-[CH.sub.2]Ph).sub.18], implying that this nanoparticle has the same surprising stellated (staples) structure.

The two-step thermal decomposition method from barium titanyl oxalate nanoparticles were used to prepare barium titanate (BaTi[O.sub.3]) nanoparticles from 27 to 192 nm. The newly obtained dense BaTi[O.sub.3] nanoparticle sphere arrays were used to measure a size dependence of temperature versus crystal structure and size dependence of temperature versus dielectric constant.

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 experimental model for the deposition of silver lines and films via the impaction of a silver nanoparticle aerosol delivered through a supersonic jet is described. It is found that, for a given gas type, the size of the grains and morphological features within the impacted films were similar to the size of the nanoparticles from which the films were formed.

The structural and magnetic properties of the [Sn.sub.1-x][Mn.sub.x][O.sub.2] nanocrystalline powders which was synthesized by a wet chemical method is discussed. The results indicate that Mn element acts as [Mn.sup.4} for x = 0.01 and as [Mn.sup.3} for x = 0.02 and 0.04 at room temperature, but as [Mn.sup.3} for all the samples of 5 K.

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 highly luminescent terbium nanoparticle as the biolabel based on the sensitization of a dye molecule was prepared. The luminescent complexes included in the particles were composed of a quinolone-based dye molecule as the light-energy transfer donor and a polyaminocarboxylate-based chelator with excellent water-solubility and a high binding constant for lanthanides. The structure of two functional entities in the single molecule made the complex highly luminescent in aqueous solution. Silica nanoparticles containing terbium complexes were prepared by the reverse microemulsion method. Such a terbium nanoparticle is as bright as about 340 free terbium complexes, and it has a 1.5-ms fluorescence lifetime that enables it to be used in the time-resolved fluorescence assays. The conjugate of the nanoparticle with oligonucleotide was prepared and used to carry out a DNA sandwich hybridization assay based on magnetic microbeads as solid-phase carder. The experimental results showed that the detection sensitivity with the nanoparticles is more than 100-fold as high as that with dye Fluorescein isothiocyanate (FITC) molecules.

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.

Laser ablation of a platinum target in pure water at 355 nm wavelength is analyzed as a function of laser energy. It is demonstrated that laser ablation of platinum metal plate in water can produce platinum hydroxides and oxides through reaction of ablated species with water in three distinct processes depending on the laser focusing conditions and that significant tunability in the target-liquid interaction is possible during nanomaterial synthesis by laser ablation.

The effect of the laser wavelength and fluence on the mass yield and size distribution of nanoparticles prepared by laser ablation of a platinum target immersed in water was studied. Nanoparticle size distributions were found to be composed of two components attributed to thermal vaporization and explosive boiling mechanisms and it was shown that the size distribution of particles formed after thermal vaporization is relatively constant in size and width for all conditions.

The growth process of nanoparticles and nanowires of AlN by thermal-plasma-assisted gas phase condensation reaction has been investigated by optical emission spectroscopy. The concentrations of the reacting precursors in the plasma have been correlated to the crystalline phases of nanoparticles of AlN found from X-ray diffraction analysis. The size and morphology of the nanoparticles have been studied by transmission electron microscope investigations of as-synthesized powder at a set of reactor parameters, which included arc current, reactor pressure, and standoffs of the arc column. An attempt has been made to correlate the growth of AlN to that of the precursor density present in the plasma reaction zone. Index Terms--Nanoparticle synthesis, optical emission spectroscopy (OES), plasma arc devices.

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.

This work describes the development and demonstration of a non-scanning chemical imaging probe, capable of obtaining surface-enhanced Raman scattering (SERS) images of samples with which it is in direct contact. The SERS imaging arrays (i.e., nanoprobes) are used in a signal collection mode to obtain images by measuring as many as 30 000 individual sub-diffraction-limited locations on a sample's surface simultaneously. These SERS probes are fabricated from coherent fiber-optic imaging bundles, allowing for the formation of a highly ordered roughened metal surface, capable of providing uniform SERS enhancement (< 2.0% relative standard deviation) across the entire imaging surface. These optimized SERS nanoprobes have potential application to a wide range of research fields from materials science to cellular biology.

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.

Structural and electronic properties of TiO2 nanoparticles sensitized with a set of [Ru.sup.II](tpy)2 based dyes are investigated using density functional theory (DFT) calculations combined with time-dependent (TD) DFT calculations. Inclusion of explicit counterions in the modeling reveals that the description of the environment is important in order to obtain a realistic interfacial energy level alignment.

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.

The effect of geometrical parameters and metal composition on the sensitivity of the plasmon response (frequency and bandwidth) of Ag, Au, and their alloy nanorods to changes in the refractive index of the surrounding medium is investigated. The calculations show that the plasmon resonance sensitivity does not change with the metal composition and Ag, Au and Ag-Au alloy nanorods have similar sensitivity at the same size and shape.

A vertical-flow surround-gate Schottky-barrier transistor is demonstrated using a new technique in forming the cubic single-crystal silicon nanoparticles that are about 40 nm on a side. The fabrication process involves successive deposition and planerization and does not require nonoptical lithography while the device characteristics show reasonable turn-off and on-current densities of more than 10[super 7] A/cm[super 2].

We herein demonstrate a new sensing method for phosphopeptides by localized surface plasmon resonance (LSPR) using titania-coated gold nanoparticles immobilized on the surface of a glass slide as the sensing substrate and using UV-visible spectrophotometry as the detection tool. Titania has been known to be an effective substrate for binding with phosphorylated species. The detection principle is the shift of wavelength of optical absorption due to SPR of the gold nanoparticles induced by binding of phosphorylated species with titania on the surface of the gold nanoparticles. The feasibility of the approach is demonstrated by detection of tryptic digest products of [beta]-casein and milk. Gold nanoparticles coated with thin films of titania, immobilized on a glass slide, can selectively bind traces of phosphopeptides from complex samples, resulting in a wavelength shift of the absorption band in the SPR spectrum with good reproducibility. The LSPR results are confirmed by matrix-assisted laser desorption/ionization mass spectrometry. The detection limit for the tryptic digest product of [beta]-casein is 50 nM.

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.

N-containing Ti[O.sub.2]-based nanostructured materials with an anatase-type structure are investigated by using oxygen (O) K-edge and titanium (Ti) K- and L-edge X-ray absorption near-edge spectroscopy (XANES). The influence of N-doping on titania nanoparticles and their structure, electronics and photocatalytic activity is discussed.

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.