Differential protein expression of Caco-2 cells treated with selenium nanoparticles compared with sodium selenite and selenomethionine

The study was designed to determine the differential protein expression of Caco-2 cells treated with different forms of selenium including sodium selenite, selenomethionine (Se-Met), and selenium nanoparticles (nano-Se). Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry (MS) were used to identify the differentially expressed proteins. The results indicated that seven protein spots, ubiquitin-conjugating enzyme E2 (E2), glutathione synthetases (GS), triosephosphate isomerase (TSP), T-complex protein 1 subunit zeta (TCPZ), lamin-B1, heterogeneous nuclear ribonucleoprotein F (hnRNP F), and superoxide dismutase [Cu-Zn] (Cu, Zn-SOD) were significantly different among all the groups. According to the order of control, sodium selenite, Se-Met, and Nano-Se, the expression levels of two proteins (E2 and GS) increased and the other differential proteins were reverse. Except for E2, there were no significant differences in other protein expressions between the groups treated with nano-Se and Se-Met.     

Calcium-dependent cyto- and genotoxicity of nickel metal and nickel oxide nanoparticles in human lung cells

Background

Genotoxicity is an important toxicological endpoint due to the link to diseases such as cancer. Therefore, an increased understanding regarding genotoxicity and underlying mechanisms is needed for assessing the risk with exposure to nanoparticles (NPs). The aim of this study was to perform an in-depth investigation regarding the genotoxicity of well-characterized Ni and NiO NPs in human bronchial epithelial BEAS-2B cells and to discern possible mechanisms. Comparisons were made with NiCl₂ in order to elucidate effects of ionic Ni.

Methods

BEAS-2B cells were exposed to Ni and NiO NPs, as well as NiCl₂, and uptake and cellular dose were investigated by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS). The NPs were characterized in terms of surface composition (X-ray photoelectron spectroscopy), agglomeration (photon cross correlation spectroscopy) and nickel release in cell medium (ICP-MS). Cell death (necrosis/apoptosis) was investigated by Annexin V-FITC/PI staining and genotoxicity by cytokinesis-block micronucleus (cytome) assay (OECD 487), chromosomal aberration (OECD 473) and comet assay. The involvement of intracellular reactive oxygen species (ROS) and calcium was explored using the fluorescent probes, DCFH-DA and Fluo-4.

Results

NPs were efficiently taken up by the BEAS-2B cells. In contrast, no or minor uptake was observed for ionic Ni from NiCl₂. Despite differences in uptake, all exposures (NiO, Ni NPs and NiCl₂) caused chromosomal damage. Furthermore, NiO NPs were most potent in causing DNA strand breaks and generating intracellular ROS. An increase in intracellular calcium was observed and modulation of intracellular calcium by using inhibitors and chelators clearly prevented the chromosomal damage. Chelation of iron also protected against induced damage, particularly for NiO and NiCl₂.

Conclusions

This study has revealed chromosomal damage by Ni and NiO NPs as well as Ni ionic species and provides novel evidence for a calcium-dependent mechanism of cyto- and genotoxicity.

     

A selective and convenient synthesis of 2-(bis(2-hydroxyethyl)amino)ethyl alkanoate over mixed metal oxides

Esterification reactions carried out using various mineral acids are threat to environment hence process modification using commercially viable heterogeneous catalysts are in demand. In current work, the esterification of tri-ethanolamine (TEA, C₆H₁₅O₃N) with several fatty acids in liquid phase has been investigated on a series of heterogeneous mixed metal oxides catalyst prepared by co-precipitation method, crystallizing with spinel lattice such as, CuFe₂O₄, ZnFe₂O₄, CoFe₂O₄, NiFe₂O₄ and 10% (w/w) ZnFe₂O₄ supported on SiO₂ and ZrO₂. The best catalyst for the selective preparation of 2-(bis(2-hydroxyethyl)amino)ethyl alkanoate was 10% (w/w) ZnFe₂O₄ supported on ZrO₂. Detail comparison of a 10% (w/w) ZnFe₂O₄/ZrO₂ prepared by co-precipitation method was carried out with 10% (w/w) ZnFe₂O₄/ZrO₂ prepared by template route for the selective formation of 2-(bis(2-hydroxyethyl)amino)ethyl alkanoate. The effects of variety of parameters including effect of catalyst preparation were studied in a batch reactor.     

Metal and metal oxide nanoparticle synthesis from metal organic frameworks (MOFs): finding the border of metal and metal oxides

Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co(3)O(4), ZnO, Mn(2)O(3), MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N(2), whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N(2). Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N(2) and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H(2) and CO(2) adsorption properties depending on the environment used for the thermolysis of MOFs.     

Enhanced properties of solid solution (CeZr)O2 modified with metal oxides for catalytic oxidation of low-concentration methane

The solid solution (CeZr)O2 catalyst was synthesized, and it was modified with metal oxides by incipient impreg-nation. Morphology and structure were characterized by X-ray diffraction, transmission electron microscope, ni-trogen ad/desorption and H2-temperature program reduction techniques. The catalytic properties of methane oxidation were also investigated. The results showed that solid solution possessed a mesoporous structure and exhibited excellent catalytic performance. The activity of solid solution was improved effectively by nickel dop-ing, and the optimal loading is 15 wt%. The stability of (CeZr)O2 and modified (CeZr)O2 indicated that the struc-ture of pristine solid solution played a key role in promoting molecules diffusion and spatial confining oxide particle sintering.     

Crosslinking of poly(vinyl chloride) with metal oxides,sulfur, and organo sulfur compounds

The crosslinking of poly(vinyl chloride) in the presence of zinc oxide, magnesium oxide, ethylenethiourea (ETU), tetramethylthiuramdisulfide (TMTD), and sulfur at 160 and 180°C has been studied. The effects of ETU and sulfur on the crosslinking of PVC in the presence of TMTD have been individually studied. It has been found that zinc dimethyldivhiocarbamate (ZnDMDC) is the actual crosslinking agent and heat stabilizer of PVC, formed in the cured polymer mix.     

Biofabrication of gold nanoparticles and its biocompatibility in human breast adenocarcinoma cells (MCF-7)

In this paper, a simple and environmentally friendly method for synthesis of gold nanoparticles (AuNPs) using culture supernatant of Bacillus flexus as reductants and stabilizers is reported. The prepared AuNPs were characterized by various analytical techniques. UV–visible spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) results confirmed that Au³⁺ ions reduced into Au⁰. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements confirmed that the chemical surface structure of AuNPs. TEM images showed the size and morphology of AuNPs. Moreover, the toxicity studies suggested that AuNPs were neither toxic nor inhibitory to human breast cancer cells (MCF-7).     

Thermal stability and deformation of poly(acrylic acid)–metal oxides

In this work, we investigated the thermal stability and deformation of the compound of poly(acrylic acid) (PAA) and metal oxides (ZnO, CaO, CuO, Al₂O₃, and Cr₂O₃). The kinetic parameters of the desorption of water from PAA–metal oxide were calculated. The activation energies of the water desorption of PAA–metal oxide were less than 5 kcal/mol. The order of bonding capability of oxygen (PAA–O–metal) and water was PAA–CaO > PAA–ZnO > PAA–CuO > PAA–Cr₂O ₃ > PAA–Al₂O₃. The reaction types of the composites were clarified. Incorporating metal oxide into PAA increased the thermal stability. The factors which influence the mechanical properties of the composites, e.g., the chemical compositions, curing environment, and curing time, were also studied. The various curing environments (pure water, 0.1N HCl, 0.1N NaOH, and methanol) decreased the compressive strength of PAA—metal oxide. Moreover, the thermal stability and compressive strength of PAA–ZnO and PAA–CuO reached an optimum because of their crosslinking nature. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2021–2027, 1997     

Electrochemical performance and stability of thin film electrodes with metal oxides in polymer electrolyte fuel cells

Thin film electrodes are prepared by thermal evaporation of nanometer thick layers of metal oxide and platinum on a gas diffusion layer (GDL), in order to evaluate different metal oxides’ impact on the activity and stability of the platinum cathode catalyst in the polymer electrolyte fuel cell. Platinum deposited on tin, tantalum, titanium, tungsten and zirconium oxide is investigated and the morphology and chemistry of the catalysts are examined with scanning electron microscopy and X-ray photoelectron spectroscopy. Cyclic sweeps in oxygen and nitrogen are performed prior and after potential cycling degradation tests. Platinum seems to disperse better on the metal oxides than on the GDL and increased electrochemically active surface area (ECSA) of platinum is observed on tin, titanium and tungsten oxide. A thicker layer metal oxide results in a higher ECSA. Platinum deposited on tungsten performs better than sole platinum in the polarisation curves and displays higher Tafel slopes at higher current densities than all other samples. The stability does also seem to be improved by the addition of tungsten oxide, electrodes with 3 nm platinum on 3, 10 and 20 nm tungsten oxide, performs better than all other electrodes after the accelerated degradation tests.     

The interaction of rutile (TiO2) surface with some catalytically active transition metal oxides during heating,studied by electrochemical methods

The interaction of the surface of a rutile monocrystal (110 oriented) with the oxides of some transition metals (V, Mo, Cr, Mn and Nb) during heating of the crystal with these oxides was investigated by electrochemical methods. In all cases insertion of the metal atoms in the rutile surface was observed, the degree of insertion depending strongly on the metal in question and the conditions of experiment. The interaction of rutile surface with metal oxides changes dramatically the conditions of charge transfer at the rutile surface, which may influence the course of catalytic reactions occurring at the surface of rutile-supported transition metal oxide catalysts. This revised version was published online in June 2006 with corrections to the Cover Date.     

Preparation and phase evolution of high-entropy oxides A2B2O7 with multiple elements at A and B sites

In this study, 37 kinds of high-entropy pyrochlore/fluorite ceramics with equiatomic multicomponent compositions were successfully synthesized and the process of phase transformation was also investigated. Eventually, the experimental results show that 33 among the high-entropy compounds exhibit a single pyrochlore/fluorite structure with all cations randomly and uniformly distributed at A and B sites. Meanwhile, the ionic radii, valence, and size disorder may be the main driving forces for the formation of single-phase high-entropy pyrochlore/fluorite oxides. Furtherly, the average radius ratio(r_A/r_B) is the main factor of the pyrochlore/fluorite phase transformation. And when the average radius ratio(r_A/r_B) extends from 1.46 to 1.78, the high-entropy pyrochlore structure is stable. When the average radius ratio r_A/r_B is less than 1.46, it transforms into the defective fluorite structure. This study not only further expands the high-entropy pyrochlore family and but also is expected to guide the design of high-entropy pyrochlore through composition customization.     

Gd,B共掺杂改性TiO_2纳米颗粒的可见光光催化活性

采用溶胶-凝胶法制备了Gd和B共掺杂的TiO2纳米颗粒,研究了TiO2纳米颗粒在可见光下的光催化活性。应用XRD、TEM和UV-Vis等手段对TiO2纳米颗粒的物相、粒径、形貌及光学性能进行了表征。结果表明,掺杂可以抑制TiO2晶粒增长,阻碍TiO2由锐钛矿相向金红石相的转变。紫外-可见吸收光谱显示,共掺杂纳米颗粒在可见光区吸收有较强提高,共掺杂离子以协同作用拓展TiO2光谱响应,使吸收带产生红移,提高光生载流子的分离效率。光催化降解实验表明,共掺杂TiO2纳米颗粒有很高的可见光光催化活性,以500℃热处理的共掺杂摩尔比为0.005 Gd和0.04 B的TiO2纳米颗粒光催化效果最好,在可见光下对甲基橙的降解率为98.9%。     

Adsorption studies of Cr(VI) and Cu(II) metal ions from aqueous solutions by synthesized Ag and Mg co-doped TiO2 nanoparticles

ABSTRACT

This communication provides the eliminating of heavy metals from water resources using Ag-Mg/TiO₂ nanoparticles. The nanoparticles with a size of 15 nm were prepared using sol-gel technique and used for the removal of Cr(VI) and Cu(II) from waste waters. Batch sorption studies were carried out to investigate the adsorption of the above metal ions for a concentration range of 0.1–10 mg/L. The maximum sorption capacity values were found to be 2.42 mg/g for Cr(VI) and 2.03 mg/g for Cu(II) at a concentration of 0.1 ppm. The mechanism of adsorption was also investigated. The results showed that both Freundlich and Dubinin–Radushkevitch isotherms were found to be the best fit for the adsorption of metals. The results from kinetic data reveal that the pseudo-second-order and Reichenberg film diffusion models were found to be well fit for the experimental data. The value of the thermodynamic parameter ΔH° revealed the endothermic adsorption process and negative value of ΔG° shows the feasibility and spontaneity of material–anion interaction. In addition, the method is considered to be simple and cost-effective, and shows excellent adsorption removal properties on heavy metals for industrial applications.     

Preparation and photocatalytic property of spindle-like MIL-88B(Fe) nanoparticles

Iron(III) based nanoparticles MIL-88B(Fe) with spindle-like morphology were synthesized by a facile method. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed that the MIL-88B(Fe) nanoparticles had an uniform size of about 385 nm in length and 195 nm in width. The obtained nanoparticles were further characterized by powder X-ray diffraction (XRD) and ultraviolet-visible spectroscopy (UV–vis). Moreover, as MIL-88B(Fe) shows obvious adsorption in the visible region, it has good degradation activity for methylene blue (MB) and rhodamine B (RB) dye under visible light.     

CeO(2)/rGO/Pt sandwich nanostructure: rGO-enhanced electron transmission between metal oxide and metal nanoparticles for anodic methanol oxidation of direct methanol fuel cells

Pt-based nanocomposites have been of great research interest. In this paper, we design an efficient MO/rGO/Pt sandwich nanostructure as an anodic electrocatalyst for DMFCs with combination of the merits of rigid structure of metallic oxides (MOs) and excellent electronic conductivity of reduced oxidized graphene (rGO) as well as overcoming their shortcomings. In this case, the CeO(2)/rGO/Pt sandwich nanostructure is successfully fabricated through a facile hydrothermal approach in the presence of graphene oxide and CeO(2) nanoparticles. This structure has a unique building architecture where rGO wraps up the CeO(2) nanoparticles and Pt nanoparticles are homogeneously dispersed on the surface of rGO. This novel structure endows this material with great electrocatalytic performance in methanol oxidation: it reduces the overpotential of methanol oxidation significantly and its electrocatalytic activity and stability are much enhanced compared with Pt/rGO, CeO(2)/Pt and Pt/C catalysts. This work supplies a unique MO/rGO/Pt sandwich nanostructure as an efficient way to improve the electrocatalytic performance, which will surely shed some light on the exploration of some novel structures of electrocatalyst for DMFCs.     

Green synthesis of anisotropic silver nanoparticles and its potential cytotoxicity in human breast cancer cells (MCF-7)

We described a green, cost effective and rapid method for synthesizing anisotropic AgNPs using a novel bacterium called Escherichia fergusoni. Furthermore, synthesized AgNPs were characterized by various analytical techniques. The present study demonstrates the efficiency of biologically synthesized AgNPs as a cytotoxic agent against MCF-7 cells and also this study investigates possible molecular mechanisms underlying the cytotoxic effects of AgNPs. AgNPs showed dose dependent cytotoxicity against MCF-7 cells through activation of the lactate dehydrogenase (LDH), reactive oxygen species (ROS) generation and eventually leading to induction of apoptosis which was further confirmed through resulting nuclear fragmentation.     

Development of stealth nanoparticles coated with poly(2-methoxyethyl vinyl ether) as an alternative to poly(ethylene glycol)

Poly(ethylene glycol) (PEG) modification, also known as PEGylation, has been extensively used to improve the stability of nanoparticles for nanomedical applications. However, PEG exhibits antigenicity in some formulations, motivating researchers to explore alternative polymers. Herein, poly(vinyl ether) (PVE) derivatives are highlighted as promising alternatives to PEG because they form intermediate water molecules that suppress non-specific protein adsorption and platelet adhesion to the material surface. We prepared a water-soluble PVE derivative, poly(2-methoxyethyl vinyl ether) (PMOVE), and utilized it as a surface modifier for gold nanoparticles (AuNPs) as model nanoparticles. PMOVE with a thiol terminus was synthesized and confirmed to form an intermediate water molecule using differential scanning calorimetry. Similar to the synthesis of PEGylated AuNPs (PEG-AuNPs), PMOVE-modified AuNPs (PMOVE-AuNPs) were successfully fabricated with an appreciably high density of PMOVE palisades via a thiol-gold coordination reaction. Similar to PEG-AuNPs, PMOVE-AuNPs showed reduced serum protein adsorption and prolonged blood circulation. Additionally, no significant cytotoxicity was observed after incubation of a murine macrophage cell line, RAW264.7, with PMOVE-AuNPs. Our results indicate that the PMOVE modification increases the stealthiness of nanoparticles that is equivalent to that achieved by PEGylation.     

Facile method to synthesize magnetic iron oxides/TiO2 hybrid nanoparticles and their photodegradation application of methylene blue

The primary objective of this study is to investigate the effect of slip mechanisms in nanofluids through scaling analysis. The role of nanoparticle slip mechanisms in both water- and ethylene glycol-based nanofluids is analyzed by considering shape, size, concentration, and temperature of the nanoparticles. From the scaling analysis, it is found that all of the slip mechanisms are dominant in particles of cylindrical shape as compared to that of spherical and sheet particles. The magnitudes of slip mechanisms are found to be higher for particles of size between 10 and 80 nm. The Brownian force is found to dominate in smaller particles below 10 nm and also at smaller volume fraction. However, the drag force is found to dominate in smaller particles below 10 nm and at higher volume fraction. The effect of thermophoresis and Magnus forces is found to increase with the particle size and concentration. In terms of time scales, the Brownian and gravity forces act considerably over a longer duration than the other forces. For copper-water-based nanofluid, the effective contribution of slip mechanisms leads to a heat transfer augmentation which is approximately 36% over that of the base fluid. The drag and gravity forces tend to reduce the Nusselt number of the nanofluid while the other forces tend to enhance it.     

Cellular uptake, cytotoxicity, and metabolic profiling of human cancer cells treated with ruthenium(II) polypyridyl complexes [Ru(bpy)2(N--N)]Cl2 with N--N=bpy, phen, dpq, dppz, and dppn

A series of five ruthenium(II) polypyridyl complexes [Ru(bpy)2(N--N)]Cl2 was tested against human HT-29 and MCF-7 cancer cell lines. Cellular uptake efficiency and cytotoxicity were found to increase with the size of the aromatic surface area of the N--N ligand. The most active compound carrying the dppn ligand exhibits a low micromolar IC(50) value against both cell lines comparable to that of cisplatin under similar conditions. Continuous measurement of oxygen consumption, extracellular acidification rate, and impedance of the cell layer with a chip-based sensor system upon exposure to the complexes showed only small changes for the first two parameters throughout the series. A significant and irreversible decrease in impedance was, however, found for the dppn compound. This suggests that its biological activity is related to modifications in cell morphology or cell-cell and cell-matrix contacts.