Photocatalytic activity of an electrophoretically deposited composite titanium dioxide membrane using carbon cloth as a conducting substrate

This is the first report where a polymer, namely poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP), has been used as a binder together with the electrophoretic deposition process.

One-pot sonochemical synthesis of ferrocenyl derivatives via a three-component reaction in aqueous media

An ultrasound-assisted three-component, one-pot domino reaction with ferrocenecarboxaldehyde is herein reported. The sequence of reactions entails the allylindation and dehydrative alkylation of stabilized C-nucleophiles (e.g. electron-rich-(hetero)aromatics and stabilized enols) and N-nucleophiles (e.g. azoles). Sonochemical reactions have been performed in three different high-intensity reactors: a bath (20.3 kHz, 60 W), as well as two cup horns working at 19.9 kHz (75 W) and 300.5 kHz (70 W) giving a library of 18 new ferrocenyl derivatives.

Heterogeneous Photocatalysis and Photoelectrocatalysis: From Unselective Abatement of Noxious Species to Selective Production of High-Value Chemicals

Heterogeneous photocatalysis and photoelectrocatalysis have been considered as oxidation technologies to abate unselectively noxious species. This article focuses instead on the utilization of these methods for selective syntheses of organic molecules. Some promising reactions have been reported in the presence of various TiO2 samples and the important role played by the amorphous phase has been discussed. The low solubility of most of the organic compounds in water limits the utilization of photocatalysis. Dimethyl carbonate has been proposed as an alternative green organic solvent. The recovery of the products by coupling photocatalysis with pervaporation membrane technology seems to be a solution for future industrial applications. As far as photoelectrocatalysis is concerned, a decrease in recombination of the photogenerated pairs occurs, enhancing the rate of the oxidation reactions and the quantum yield. Another benefit is to avoid reaction(s) between the intermediates and the substrate, as anodic and cathodic reactions take place in different places.

Solution thermodynamics, computational and relaxometric studies of ditopic DO3A-based Mn(ii) complexes

The structure, stability and magnetic properties of novel ditopic Mn(ii)-complexes were studied by molecular modeling, potentiometric and relaxometric techniques.

Nanostructured anatase TiO2 densified at high pressure as advanced visible light photocatalysts

Uniaxial high pressure up to 2.1 GPa on anatase TiO₂ nanopowders induces structural defects, increases visible light absorption and enhances acetaldehyde production.

Catalysis in glycerol: a survey of recent advances

There is currently a significant increase in the use of glycerol as a renewable solvent for catalytic reactions. Glycerol has often been the solvent of choice in both homogeneous and heterogeneous catalyses, despite its high viscosity at ambient temperature and the low solubility of highly hydrophobic reagents found in glycerol. Its biodegradability and non-toxicity have led to reports of improved reaction performance and selectivity, as well as easier product separation and effective catalyst recycling. All relevant advances in this emerging field of “green” catalysis are thoroughly reviewed below.

Visible-light driven oxidation of gaseous aliphatic alcohols to the corresponding carbonyls via TiO2 sensitized by a perylene derivative

Sensitized P25 TiO2 was prepared by wet impregnation with a home-prepared perylene dye, i.e., N,N'-bis(2-(1-piperazino)ethyl)-3,4,9,10-perylene-tetracarboxylic acid diimide dichloride (PZPER). Energy levels of PZPER were found to be compatible with those of TiO2 allowing fast electron transfer. The obtained catalyst has been characterized and used in the gas-phase partial oxidation of aliphatic primary and secondary alcohols, i.e., methanol, ethanol, and 2-propanol. The reaction was carried out under cut-off (λ > 400 nm) simulated solar radiation in O2 atmosphere. The perylene derivative allowed a good absorbance of visible radiation thanks to its low optical energy gap (2.6 eV) which was evaluated by cyclic voltammetry. The optimal organic sensitizing amount was found to be 5.6 % w/w in terms of yield in carbonyl derivatives. Moreover, no change in reactivity/selectivity was observed after 10-h irradiation thus confirming the catalyst stability. Yields into formaldehyde, acetaldehyde, and acetone were 67, 70, and 96 %, respectively. No significant amounts of organic byproducts were detected but for methanol oxidation, whereas a minor amount of the substrate degraded to CO2.

Combination of ozonation and photocatalysis for purification of aqueous effluents containing formic acid as probe pollutant and bromide ion

The treatment by advanced oxidation processes (AOPs) of waters contaminated by organic pollutants and containing also innocuous bromide ions may generate bromate ions as a co-product. In the present work heterogeneous photocatalysis and ozonation have individually been applied and in combination (integrated process) to degrade the organic compounds in water containing also bromide anions. The results show that: i) the sole photocatalysis does not produce bromate ions and in the case of its presence, it is able to reduce bromate to innocuous bromide ions; ii) the integration of photocatalysis and ozonation synergistically enhances the oxidation capabilities; and iii) in the integrated process bromate ions are not produced as long as some oxidizable organics are present.

Sol-gel entrapped visible light photocatalysts for selective conversions

A new photoactive, low-cost nanomaterial to harvest solar energy and use it a selective reactant is now available. Sol–gel encapsulation of flower-like Bi₂WO₆ into transparent silica glass affords a catalyst far more active, but still highly selective, compared to the non-entrapped species.

Halloysite nanotube with fluorinated lumen: non-foaming nanocontainer for storage and controlled release of oxygen in aqueous media

Halloysite clay nanotubes were selectivity modified by adsorbing perfluoroalkylated anionic surfactants at the inner surface. The modified nanotubes formed kinetically stable dispersions due to the enhanced electrostatic repulsions exercised between the particles. We proved that the modified nanotubes can be used as non-foaming oxygen nanocontainers in aqueous media. The gas release from supersaturated dispersions can be controlled by external stimuli and system composition. In conclusion, we managed to put forward an easy strategy to develop smart materials from natural nanoclays, which can endow important applications like the storage and delivery of gas.

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger-aza-Wittig reaction

A fast and efficient protocol for the synthesis of N,N'-disubstituted urea derivatives from alkyl halides and primary or secondary amines has been developed. The synthetic pathway combines nucleophilic substitutions and a Staudinger–aza-Wittig reaction in the presence of polymer-bound diphenylphosphine under 14 bar of CO₂ pressure and has been performed in a one-pot two-step process. The protocol has been optimized under microwave irradiation and the scale-up experiment has been conducted under conventional conditions in a Parr reactor. The final compounds were isolated after simple filtration in almost quantitative overall yields which makes this procedure facile and rapid to execute.

Two-Dimensional Modeling of an Externally Irradiated Slurry Photoreactor

A batch cylindrical photocatalytic reactor, externally irradiated by 1–6 UV fluorescent lamps and containing a stirred slurry of polycrystalline TiO2, was modeled by coupling a modified Langmuir–Hinshelwood kinetics together with a two-dimensional light intensity field. The radiation field has been determined on the main assumptions of diffuse radiation, isotropic scattering and negligible backward reflected photon flow. The model has been applied to the photocatalytic oxidation of organic substrates which do not undergo homogeneous photochemical degradation. The model is characterized by the following four parameters: the kinetic constants of substrate adsorption, desorption and degradation and the exponent of the power law expressing the kinetics dependence on the light intensity. The model constants may be determined by applying a simple least-squares best fitting procedure.

Abstract P3-04-05: Kinomic and phospho-proteomic analysis of breast cancer stem-like cells

Cancer stem cells are thought to be responsible for tumorigenic potential and to possess resistance mechanisms against chemotherapy- and radiation-induced cancer cell death, while the bulk of a tumor lacks these capacities. The resistance mechanisms may cause these cells to survive and become the source of later tumor recurrence, highlighting the need for therapeutic strategies that specifically target pathways central to these cancer stem cells. The CD44hi/CD24−/low compartment of human breast cancer is enriched in tumor-initiating cells; however the functional heterogeneity within this subpopulation remains poorly defined.

From a triple-negative breast cancer cell line we isolated and cloned CD44hi single-cells that exhibited functional heterogeneity according to cancer stem cell features, such as tumor formation in immunodeficient mice, mammosphere formation, invasion and migration abilities and sensitivity to chemotherapeutics.

Quantitative proteomic analysis of these clones revealed several proteins, including kinases, exhibiting altered expression levels, while other proteins exhibited altered phosphorylation levels. The quantitative proteomic approach was based on post digestion dimethyl labeling followed by TiO2 enrichment of phosphopeptides. Moreover, analysis of the flowthrough fraction revealed quantitative changes in the total proteome. Transcriptomic analysis using Affymetrix Human Gene 1.0 ST Arrays revealed similar alterations at the gene expression level.

We used these single cell clones to further investigate the molecular mechanisms underlying the association between selected proteins, some of them phosphorylated, and cancer stem cell features. Furthermore, phosphosite-expression was investigated with NetworKIN that predicts in vivo kinase-substrate relationships.

Our studies reveal pathways that are regulated by protein phosphorylation and include relevant kinase targets for drug discovery. Our results support functional heterogeneity in the breast cancer cell compartment and hold promise for further refinements of prognostic marker profiling of cells with cancer stem cell-like features.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-04-05.