High-surface thermally stable mesoporous gallium phosphates constituted by nanoparticles as primary building blocks

In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl3 and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C16H33(CH3)3NBr and C16PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl3 and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m(2) g(-1), and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 degrees C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis. (C) 2010 Elsevier Inc. All rights reserved.

Conatumumab (AMG 655) coated nanoparticles for targeted pro-apoptotic drug delivery

Colloidal nanoparticle drug delivery systems have attracted much interest for their ability to enable effective formulation and delivery of therapeutic agents. The selective delivery of these nanoparticles to the disease site can be enhanced by coating the surface of the nanoparticles with targeting moieties, such as antibodies. In this current work, we demonstrate that antibodies on the surface of the particles can also elicit key biological effects. Specifically, we demonstrate the induction of apoptosis in colorectal HCT116 cancer cells using PLGA nanoparticles coated with Conatumumab (AMG 655) death receptor 5-specific antibodies (DR5-NP). We show that DR5-NP preferentially target DR5-expressing cells and present a sufficient density of antibody paratopes to induce apoptosis via DR5, unlike free AMG 655 or non-targeted control nanoparticles. We also demonstrate that DR5-targeted nanoparticles encapsulating the cytotoxic drug camptothecin are effectively targeted to the tumour cells, thereby producing enhanced cytotoxic effects through simultaneous drug delivery and apoptosis induction. These results demonstrate that antibodies on nanoparticulate surfaces can be exploited for dual modes of action to enhance the therapeutic utility of the modality. (C) 2011 Elsevier Ltd. All rights reserved.

Modification of Ag nanoparticles with mixed thiols for improved SERS detection of poorly adsorbing target molecules: detection of MDMA

Here we report an example of a mixed thiol monolayer on the surface of Ag nanoparticles which promotes adsorption and quantitative SERS detection of 3,4-methylenedioxymethamphetamine (MDMA, “Ecstasy”); the thiols in the mixed monolayers act synergistically since MDMA does not adsorb onto colloids modified with either of the thiols separately.

Structure of Adenine on Metal Nanoparticles: pH Equilibria and Formation of Ag+ Complexes Detected by Surface-Enhanced Raman Spectroscopy

The SERS spectra of adenine recorded under a broad range of pH values and concentrations using both silver and gold colloids provided evidence for the existence of several distinct species. At high concentration (0.5-10 ppm), the spectra recorded between pH 1 and 11 showed only two distinct spectra, rather than the three forms that would be expected for a compound with two pK(a) values of 4.2 and 9.8. The spectra at neutral and alkaline pH were identical and assigned to the deprotonated form of adenine on the basis of DFT calculations, isotope shifts, and comparison with the normal Raman spectra of neutral and deprotonated adenine. The spectra at acidic pH were different, consistent with adenine protonation. Neutral adenine was not detected at any pH studied. At low adenine concentration (

Fabrication of cerium oxide nanoparticles: Characterization and optical properties

Ceria (CeO2) is a technologically important rare earth material because of its unique properties and various engineering and biological applications. A facile and rapid method has been developed to prepare ceria nanoparticles using microwave with the average size 7 nm in the presence of a set of ionic liquids based on the bis (trifluoromethylsulfonyl) imide anion and different cations of 1-alkyl-3-methyl-imidazolium. The structural features and optical properties of the nanoparticles were determined in depth with X-ray powder diffraction, transmission electron microscope, N-2 adsorption-desorption technique, dynamic light scattering (DLS) analysis, FTIR spectroscopy, Raman spectroscopy, UV-vis absorption spectroscopy, and Diffuse reflectance spectroscopy. The energy band gap measurements of nanoparticles of ceria have been carried out by UV-visible absorption spectroscopy and diffuse reflectance spectroscopy. The surface charge properties of colloidal ceria dispersions in ethylene glycol have been also studied. To the best of our knowledge, this is the first report on using this type of ionic liquids in ceria nanoparticle synthesis. (C) 2011 Elsevier Inc. All rights reserved.

Preparation, structural characterization, semiconductor and photoluminescent properties of zinc oxide nanoparticles in a phosphonium-based ionic liquid

A convenient microwave method in preparation of zinc oxide nanoparticles (ZnONPs) using an ionic liquid, trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}-imide, [P-66614][NTf2], as a green solvent is described in this paper. To the best of our knowledge, there is no report for synthesizing any nanoparticle using this ionic liquid. Trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}-imide has low interface tension and thus it can enhance the nucleation rate, which is favorable to the formation of smaller ZnONPs. The fabricated ZnONPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis spectroscopy. The XRD pattern reveals that the ZnONPs have hexagonal wurtzite structure. The strong intensity and narrow width of ZnO diffraction peaks indicate that the resulting nanoparticles are of high crystallinity. The synthesized ZnONPs show direct band gap of 3.43 eV. The UV-vis absorption spectrum of ZnONPs dispersed in ethylene glycol at room temperature revealed a blue-shifted onset of absorption. (C) 2011 Elsevier Ltd. All rights reserved.

DNA Reorientation on Au Nanoparticles: Label-Free Detection of Hybridization by Surface Enhanced Raman Spectroscopy

DNA sequences attached to Au nanoparticles via thiol linkers stand up from the surface, giving preferential enhancement of the adenine ring breathing SERS band. Non-specific binding via the nucleobases reorients the DNA, reducing this effect. This change in intensity on reorientation was utilised for label-free detection of hybridization of a molecular beacon.

Orotate complexes of rhodium(I) and iridium(I): effect of coligand, counter ion, and solvent of crystallisation on association via complementary hydrogen bonding

The new complexes [NEt3H][M(HL)(cod)] (M = Rh 1 or Ir 2; H3L = 2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, erotic acid; cod = cycloocta-1,5-diene) have been prepared by the reaction between [M2Cl2(cod)(2)] and erotic acid in dichloromethane in the presence of Ag2O and NEt3. They crystallise as dichloromethane adducts 1 . CH2Cl2 and 2 . CH2Cl2 from dichloromethane-hexane solutions. These isomorphous structures contain doubly hydrogen-bonded dimers, with additional hydrogen bonding to NEt3H+ cations and bridging CH2Cl2 molecules to form tapes. The use of (NBu4OH)-O-n instead of NEt3 gave the related complex [NBu4n][Rh(HL)(cod)] 1' which has an innocent cation not capable of forming strong hydrogen bonds and in contrast to 1 exists as discrete doubly hydrogen-bonded dimers. Complex 1' cocrystallises with 2,6-diaminopyridine (dap) via complementary triple hydrogen bonds to give [NBu4n][Rh(HL)(cod)]. dap . CH2Cl2 3. Complex 3 exhibits an extended sheet structure of associated [2 + 2] units, with layers of NBu4n, cations separating the sheets. These structural data together with those reported previously for platinum orotate complexes suggest that the steric requirements of the other ligands co-ordinated to the metal are important in influencing their hydrogen-bonding abilities. The solvent of crystallisation, the hydrogen-bonding propensity of the coligand and the nature of the counter ion also determine the type of association in the solid state.

Bridging the Gap between CO Adsorption Studies on Gold Model Surfaces and Supported Nanoparticles

A happy medium: Volumetric adsorption of carbon monoxide at 308 K and UHR-HAADF-STEM, HREM, and computer modeling techniques were compared. Experimental CO/Au ratios at saturation coverage for two supported gold catalysts were shown to fit very well the predictions of a nanostructural model that considers CO adsorption on gold sites with coordination numbers of less than eight.

Facile in situ synthesis of nanofluids based on ionic liquids and copper oxide clusters and nanoparticles

Two stable nanofluids comprising of mixed valent copper(_I,_II) oxide clusters (<1 nm) suspended in 1-butyl-3-methylimidazolium acetate, [C(₄)mim][OAc], and copper(_II) oxide nanoparticles (<50 nm) suspended in trioctyl(dodecyl) phosphonium acetate, [P-₈₈₈₁₂][OAc], were synthesised in a facile one-pot reaction from solutions of copper(_II) acetate hydrate in the corresponding ionic liquids. Formation of the nanostructures was studied using ¹³C NMR spectroscopy and differential scanning calorimetry (DSC). From a solution of Cu(OAc)₂ in 1-ethyl-3-methylimidazolium acetate, [C₂mim][OAc], crystals were obtained that revealed the structure of [C₂mim][Cu₃(OAc)₅(OH)₂(H₂O)]center dot H₂O, indicating the formation of copper hydroxo-clusters in the course of the reaction. Synthesised nanostructures were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Physical properties of the prepared IL-nanofluids were examined using IR and UV-VIS spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and densitometry. 

Nanodosimetric effects of gold nanoparticles in megavoltage radiation therapy

Background and purpose: The addition of gold nanoparticles (GNPs) to tumours leads to an increase in dose due to their high density and energy absorption coefficient, making it a potential radiosensitiser. However, experiments have observed radiosensitisations significantly larger than the increase in dose alone, including at megavoltage energies where gold's relative energy absorption is lowest. This work investigates whether GNPs create dose inhomogeneities on a sub-cellular scale which combine with non-linear dose dependence of cell survival to be the source of radiosensitisation at megavoltage energies.

The synthesis, characterisation and reactivity of 2-phosphanylethylcyclopentadienyl complexes of cobalt, rhodium and iridium

2-Phosphanylethylcyclopentadienyl lithium compounds, Li[C5R'(4)(CH2)(2)PR2] (R = Et, R' = H or Me, R = Ph, R' = Me), have been prepared from the reaction of spirohydrocarbons C5R'(4)(C2H4) with LiPR2. C5Et4HSiMe2CH2PMe2, was prepared from reaction of Li[C5Et4] with Me2SiCl2 followed by Me2PCH2Li. The lithium salts were reacted with [RhCl(CO)2]2,[IrCl(CO)3] or [Co-2(CO)(8)] to give [M(C5R'(4)(CH2) 2PR2)(CO)] (M = Rh, R = Et, R' = H or Me, R= Ph, R' = Me; M = Ir or Co, R = Et, R' = Me), which have been fully characterised, in many cases crystallographically as monomers with coordination of the phosphorus atom and the cyclopentadienyl ring. The values of nu(CO) for these complexes are usually lower than those for the analogous complexes without the bridge between the cyclopentadienyl ring and the phosphine, the exception being [Rh(Cp'(CH2)(2)PEt2)(CO)] (Cp' = C5Me4), the most electron rich of the complexes. [Rh(C5Et4SiMe2CH2PMe2)(CO)] may be a dimer. [Co-2(CO)(8)] reacts with C5H5(CH2)(2)PEt2 or C5Et4HSiMe2CH2PMe2 (L) to give binuclear complexes of the form [Co-2(CO)(6)L-2] with almost linear PCoCoP skeletons. [Rh(Cp'(CH2)(2)PEt2)(CO)] and [Rh(Cp'(CH2)(2)PPh2)(CO)] are active for methanol carbonylation at 150 degrees C and 27 bar CO, with the rate using [Rh(Cp'(CH2)(2)PPh2)(CO)] (0.81 mol dm(-3) h(-1)) being higher than that for [RhI2(CO)(2)](-) (0.64 mol dm(-3) h(-1)). The most electron rich complex, [Rh(Cp'(CH2)(2)PEt2)(CO)] (0.38 mol dm(-3) h(-1)) gave a comparable rate to [Cp*Rh(PEt3)(CO)] (0.30 mol dm(-3) h(-1)), which was unstable towards oxidation of the phosphine. [Rh(Cp'(CH2)(2)PEt2)I-2], which is inactive for methanol carbonylation, was isolated after the methanol carbonylation reaction using [Rh(Cp'(CH2)(2)PEt2)(CO)].

Performance and characteristics of platinum, palladium/rhodium and palladium automotive catalysts when subjected to ethanol, acetaldehyde and a synthetic E85 exhaust gas mixture

The performance optimisation of automotive catalysts has been the focus of a great deal of research for many years as the automotive industry has endeavored to reduce the emission of toxic and pollutant gases generated from internal combustion engines. Just as the emissions from diesel and gasoline combustion vary so do the emissions from combustion of alternative fuels such as ethanol; the variation is in both quantity and chemical composition. In particular, when ethanol is contained in the fuel, ethanol and acetaldehyde are present in the exhaust gas stream and these are two compounds which the catalytic converter has not traditionally been designed to manage. The aim of the study outlined in this paper was to assess the performance of various catalyst formulations when subjected to a representative ethanol exhaust gas mixture. Three automotive catalytic converter formulations were tested including a fully Pt sample, a PdRh three-way catalyst sample and a fully Pd sample. Initially the samples were tested using single component hydrocarbon light-off tests followed by a set of tests with carbon monoxide included as an inlet gas to observe its effect on each individual hydrocarbon oxidation. Finally, each formulation was tested using a full E85 exhaust gas mixture. The study was carried out using a synthetic gas reactor along with FTIR and FID exhaust gas analysers. All formulations showed selectivity toward acetaldehyde formation from ethanol dehydrogenation which resulted in negative acetaldehyde conversion across each of the samples during the mixture tests. The fully Pt sample was the most detrimentally affected by the introduction of carbon monoxide into the gas feed. The Pd and PdRh samples exhibited a tendency toward acetaldehyde decomposition resulting in methane and carbon monoxide formation. The Pt sample did not form methane but did form ethylene as a result of ethanol dehydration.