Physico-chemical properties and catalytic activity of the sol-gel prepared Ce-ion doped LaMnO3 perovskites.

Ce-doped LaMnO3 perovskite ceramics (La1-xCexMnO3) were synthesized by sol-gel based co-precipitation method and tested for the oxidation of benzyl alcohol using molecular oxygen. Benzyl alcohol conversion of ca. 25-42% was achieved with benzaldehyde as the main product. X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (H2-TPR), temperature-programmed oxidation (O2-TPO), FT-IR and UV-vis spectroscopic techniques were used to examine the physiochemical properties. XRD analysis demonstrates the single phase crystalline high purity of the perovskite. The Ce-doped LaMnO3 perovskite demonstrated reducibility at low-temperature and higher mobility of surface O2-ion than their respective un-doped perovskite. The substitution of Ce3+ ion into the perovskite matrix improve the surface redox properties, which strongly influenced the catalytic activity of the material. The LaMnO3 perovskite exhibited considerable activity to benzyl alcohol oxidation but suffered a slow deactivation with time-on-stream. Nevertheless, the insertion of the A site metal cation with a trivalent Ce3+ metal cation led to an enhanced in catalytic performance because of atomic-scale interactions between the A and B active site. La0.95Ce0.05MnO3 catalyst demonstrated the excellent catalytic activity with a selectivity of 99% at 120 °C.

Validated chiral high performance liquid chromatography separation method and simulation studies of dipeptides on amylose chiral column.

Chiral resolution of dl-alanine-dl-tyrosine and dl-leucine-dl-phenylalanine dipeptides was achieved on AmyCoat-RP column. The mobile phase used for dl-alanine-dl-tyrosine was acetonitrile-ammonium acetate (10mM, pH 6.0) [50:50, v/v]. It was acetonitrile-methanol-ammonium acetate (10mM; pH adjusted to 4.5 with glacial acetic acid) [50:20:30, v/v] for dl-leucine-dl-phenylalanine. The flow rate of the mobile phases was 0.8mL/min with UV detection at 275nm. The values of retention factors for ll-, dd-, dl- and ld-stereomers of dl-alanine-dl-tyrosine were 1.71, 2.86, 5.43 and 9.42, respectively. The values of separation and resolution factors were 1.67, 1.90 and 1.73 and 2.88, 6.43 and 7.90, respectively. Similarly, these values for dl-leucine-dl-phenylalanine stereomers were 1.50, 2.88, 3.50 and 4.07 (retention factors), 1.92, 1.22 and 1.62 (separation factors) and 2.67, 1.55 and 2.30 (resolution factors). The limits of detections and quantitation were ranged from 2.03 to 6.40 and 6.79 to 21.30µg/mL, respectively. The modeling studies were in agreement with the elution orders. The mechanism of chiral recognition was established by modeling and chromatographic studies. It was observed that hydrogen bondings and π-π interactions are the major forces for chiral separation.

Chiral xenobiotics bioaccumulations and environmental health prospectives.

The chiral xenobiotics are very dangerous for all of us due to the different enantioselective toxicities of the enantiomers. Besides, these have different enantioselective bioaccumulations and behaviors in our body and other organisms. It is of urgent need to understand the enantioselective bioaccumulations, toxicities, and the health hazards of the chiral xenobiotics. The present article describes the classification, sources of contamination, distribution, enantioselective bioaccumulation, and the toxicities of the chiral xenobiotics. Besides, the efforts are also made to discuss the prevention and remedial measures of the havoc of the chiral xenobiotics. The challenges of the chiral xenobiotics have also been highlighted. Finally, future prospectives are also discussed.

Preparation and evaluation of benzyl methacrylate monoliths for capillary chromatography.

This paper describes the comprehensive fabrication of monolithic materials for use as stationary phases in capillary liquid chromatography. Several columns were synthesized in the confines of 320 µm i.d. fused-silica capillaries by single-step in situ copolymerization of benzyl methacrylate and ethylene dimethacrylate (EDMA). The polymerization procedure was optimized by varying the reaction time within the range of 0.5-20 h, and by changing the composition contents of the polymeric mixture. The EDMA content showed a predominant influence on the characteristics of the columns and hence, on their chromatographic properties. The optimum value of the thermal initiator corresponded to 5 mg/mL. Changes of the porous, hydrodynamic properties and morphology of the prepared columns were thoroughly investigated and characterized. Different solvents were used as the mobile phase to demonstrate that the resulting monoliths exhibited good permeability and mechanical stability, whereas swelling and shrinking behaviors were observed and discussed. The efficiency and performance toward different sets of analytes were obtained; mixtures of aromatic hydrocarbons and phenolic compounds were successfully separated and evaluated, and adding tetrahydrofuran to the mobile phase showed improvement in both resolution and peak shapes. The characteristics of the columns were also checked in terms of repeatability and reproducibility.

CYP1A and POR gene mediated mitochondrial membrane damage induced by carbon nanoparticle in human mesenchymal stem cells.

Nanoparticles (NPs) can cause respiratory and cardiovascular problems, furthermore small carboxyl polystyrene NPs induce hemolysis, activate platelets and induce inflammation in human blood. Carbon nanoparticles (CNPs) are known to interfere with cellular metabolism, specific cellular functions and moreover may cause cellular toxicity. We aimed to study the influence of CNPs on oxidative stress, mitochondrial membrane damage and intracellular gene expression in human mesenchymal stem cells (hMSCs). CNPs cause a dose and time dependent growth inhibition in hMSCs at a dose range from 50 to 400µg/mL. Exposure of CNPs toxic doses viz., 50µg/mL (D1) and 100µg/mL (D2) decreased intracellular mitochondrial membrane potential compared to control. CNPs treated cells were found to lose their morphology due to cell membrane damage have been confirmed by propidium iodide staining and fluorescence microscopic analysis. Oxidative stress responsive genes like GSTM3 and GSR1 expression have increased a fold when compared to control, interim there is no change were observed in SOD and GPx. We found an increased expression of CYP1A and POR genes by at least 2- fold, which is involved in mitochondrial trans-membrane potential. In conclusion, routine and high exposure of CNPs to hMSCs increased oxidative stress and mitochondrial membrane damage.

Aluminium oxide nanoparticles induce mitochondrial-mediated oxidative stress and alter the expression of antioxidant enzymes in human mesenchymal stem cells.

An urgent need for toxicological studies on aluminium oxide nanoparticles (Al(2) [Formula: see text]NPs) has arisen from their rapidly emerging range of applications in the food and agricultural sectors. Despite the widespread use of nanoscale aluminium and its composites in the food industry, there is a serious lack of information concerning the biological activities of Al(2) [Formula: see text]NPs (ANPs) and their impact on human health. In this preliminary study, the effects of ANPs on metabolic stress in human mesenchymal stem cells (hMSCs) were analysed. The results showed dose-dependent effects, including cellular toxicity. The mitochondrial membrane potential in the hMSCs decreased with increasing ANP concentrations after 24 h of exposure. The expression levels of oxidative stress-responsive enzymes were monitored by RT-PCR. The expression levels of CYP1A and POR were up-regulated in response to ANPs, and a significant down-regulation in the expression of the antioxidant enzyme SOD was observed. Further, dose-dependent changes in the mRNA levels of GSTM3, GPX and GSR were noted. These findings suggest that the toxicity of ANPs in hMSCs may be mediated through an increase in oxidative stress. The results of this study clearly demonstrate the nanotoxicological effects of ANPs on hMSCs, which will be useful for nanotoxicological indexing.

Al2O3 nanoparticles induce mitochondria-mediated cell death and upregulate the expression of signaling genes in human mesenchymal stem cells.

An increase in the broad usage of Al2O3 nanoparticles (ANPs) in the food and agricultural sectors may produce rare hazards for human health. The objective of this study was to assess the acute toxicity of ANPs in human mesenchymal stem cells (hMSCs) in vitro. Cell viability, cellular uptake, morphology, and gene expression using quantitative real-time polymerase chain reaction (qRT-PCR) were analyzed. The results indicate that ANPs have a significant and dose-dependent effect on cytotoxicity. Control cells showed a characteristic, homogeneous nuclear staining pattern, whereas ANP-exposed cells showed abnormal nuclear morphological changes such as condensation or fragmentation. An early characteristic of apoptosis was observed in ANP-treated cells. Further confirmation of cell death in hMSCs was observed through increased expression of chosen signaling genes and also decreased expression of Bcl-2 during mitochondria-mediated cell death. Although they provide great advantages in food and agricultural products, the chronic and acute toxicity of ANPs still needs to be assessed carefully.

Effect of multi-walled carbon nanotubes incorporation into benzyl methacrylate monolithic columns in capillary liquid chromatography.

This work describes the preparation of polymer based monolithic materials and their use as stationary phases in capillary liquid chromatography. Multi-walled carbon nanotubes (MWCNT) were incorporated into a mixture containing benzyl methacrylate (BMA) and ethylene dimethacrylate (EDMA) as co-monomers. The optimized porogenic mixture was a ternary solution composed of cyclohexanol, 1,4-butandiol and butanol which resulted in a stable and homogeneous suspension. Six capillary columns with increasing amounts of MWCNT, from 0 to 0.4 mg mL(-1), were prepared by thermal polymerization in 0.32 mm (i.d.) and 150 mm length fused silica tubing. The chromatographic evaluation showed that the synthesized monolithic beds were mechanically stable while their porosity and permeability increased with the MWCNT content. The prepared capillary columns were tested for the separation of mixtures of ketones and phenols at an optimum flow rate of 2 µL min(-1). The results showed that incorporation of MWCNT slightly affected the retention while it enhanced the column efficiency by increasing the column efficiency by a factor of up to 9. This effect corresponded also to an improved resolution and full separation of the solutes.