Concentration Of Metal Oxide Nanoparticles Research Articles

Influence of Metal Oxide Nanoparticles as Antimicrobial Additives Embedded in Waterborne Coating Binders Based on Self-Crosslinking Acrylic Latex

This article deals with the simple preparation of environmentally friendly acrylic latex binders, which are functionalized with nanoparticles of metal oxides, namely MgO, ZnO, La2O3 and combinations of MgO and ZnO, serving as functional components to achieve antimicrobial properties, but also to improve physical–mechanical properties and chemical resilience. The incorporation of uncoated powder nanoparticles was performed during the synthesis, using the two-stage semi-continuous emulsion radical polymerization technique, to obtain latexes containing 0.5%–1.3% nanoparticles relative to the polymer content. Changes in latex performance due to nanoparticles were compared from the point of view of the type and concentration of metal oxide nanoparticles in latex. The results of the tests showed that all types of nanoparticles showed very promising properties, while with increasing concentration of nanoparticles there was an improvement in properties. The nanoparticles in latex provided interfacially crosslinked transparent smooth coating films with high gloss and good physical–mechanical properties. Latexes containing the highest concentration of nanoparticles provided coatings with significant antimicrobial activity against all tested bacterial and fungal strains, but also in-can preservative stability of liquid latex. Furthermore, the coatings were resistant to solvents, and in addition, latexes with MgO nanoparticles showed a significant decrease in the minimum film-forming temperature, and latex with a concentration of about 1.3% MgO did not show any flash corrosion under the coating film cast on a steel substrate. The latexes containing MgO and La2O3 nanoparticles provided coatings that were very resistant to water bleaching.

Concentration Quantification of TiO2 Nanoparticles Synthesized by Laser Ablation of a Ti Target in Water.

In this work, we present a quantitative method for determining the concentration of metal oxide nanoparticles (NP) synthesized by laser ablation in liquid. The case study was performed with titanium dioxide nanoparticles (TiO2 NP), which were synthesized by laser ablation of a Ti target in water. After synthesis, a colloidal solution was analyzed with UV-Vis spectroscopy. At the same time, the craters that remained on the Ti target after ablation were evaluated with an optical microscope to determine the volume of the ablated material. SEM microscopy was used to determine the TiO2 NP size distribution. It was found that synthesized TiO2 NP followed a Log-Normal diameter distribution with a maximum at about 64 nm. From the volume of ablated material and NP size distribution, under the assumption that most of the ablated material is consumed to form nanoparticles, a concentration of nanoparticles can be determined. The proposed method is verified by comparing the calculated concentrations to the values obtained from the Beer–Lambert law using the Mie scattering theory for the NP cross-section calculation.

<p class="Body"><strong>Acute toxicity and sublethal effects of metal oxide nanoparticles against the bulb mite</strong></p>

Crocus sativus L. (Iridaceae) known as saffron is the most commercially important medicinal food product in Iran and worldwide because of its significance for exporting commercial. However, the health of this plant is adversely threatened by abiotic and biotic stress. Bulb mite Rhizoglyphus robini Claparede (Acari: Acaridae) as abiotic stress is oligophagous and the main pest of tuber plants, commonly found in all the cultivated saffron producing areas could decrease saffron economic value. The mites tunnel through corms allowing the entry of fungal and bacterial pathogens. The widespread use of commercial pesticides in modern agriculture to protect crops from pests has caused significant public concern because of their side impacts on the environment and non-target species. Nanotechnology has been used in the production, processing, storage, packaging, and transport of agricultural products. Newly, oxide nanoparticles have been introduced as novel pesticides against pests and fertilizer. This study was conducted as an effective and environmentally-friendly method to control the growth of Rhizoglyphus robini. The lethal and sublethal effects of metal oxide nanoparticles (MNPs) including nano copper oxides (nano-CuO), nano magnesium oxide (nano-MgO), nano zinc oxide (nano-ZnO), nano titanium dioxide (nano-TiO2), and nano iron oxide (nano-Fe2O3) which their lethal concentrations ranged between 159.2 and 1036.4 mg L-1 were studied on Rhizoglyphus robini adult females. The contact effect of the tested MNPs was evaluated using the corm dip bioassay method. Assays showed that the contact toxicity of the nano-CuO treatment (229.1 mg L-1) was higher than other MNPs. To assess the sublethal effects of the MNPs, adult females were exposed to the LC25 concentration of MNPs, and life history and life-table parameters of the surviving Rhizoglyphus robini were investigated. The exposure to sublethal concentrations of the tested MNPs prolonged the egg incubation, larval period, and nymphal period significantly when compared to the control mites. Compared to other MNPs or control mite, nano-MgO and nano-TiO2 led to the longest duration of the total immature stages (11.32 and 11.32, respectively). The net reproductive rate (R0), the intrinsic rate of increase (rm), the finite rate of increase (λ), and the generation time (T) were significantly different between control and MNP treatments. The population exposed to ZnO-, MgO-, and TiO2-nanoformulations had a much lower rm value (0.164, 0.164, and 0.171 d-1, respectively) compared to the control population (0.231 d-1) and those exposed to Fe3O4- and CuO-nanoformulations (1.19 and 1.19 d-1, respectively). According to our findings, all tested MNPs, especially CuO-, ZnO-, and MgO-nano formulations, have a potential application for use in the management of Rhizoglyphus robini.

Peel bond strength between a silicone-based soft liner and a heat-cured acrylic resin denture base reinforced with three concentrations of metal oxide nanoparticles

Purpose: To evaluate the effect of incorporation of 0.1%, 0.3%, and 0.5% concentrations of titanium oxide, aluminum oxide, and silica nanoparticles in the heat-cured acrylic resin denture base on the peel bond strength to a silicone denture liner. Methods: A total number of 100 heat-cured acrylic resin samples were prepared and classified into a control group and three groups according to the type of nanoparticle. Each group was classified into three subgroups according to the concentration of the nanoparticle (n=10). A Silicone based-soft liner was added over the acrylic resin specimens, and the peel bond strength was measured using the peeling bond strength test at an angle of 90°. Statistical analysis was done using a Two-way ANOVA test for interactions between peel bond strength and the different nanoparticle materials and their concentrations. Results: Two-way ANOVA showed that the three nanoparticles and different concentrations did not affect the peel bond strength. Conclusion: The nanoparticles in this study were not effective in increasing peel bond strength at the studied concentrations.

Assessment of a heat pipe solar collector with nanofluids.

This research was designed to experimentally study the influence of using three metal oxide nanofluids at different high flow rates with various mass concentration of nanoparticles as the working fluid, on the thermal efficiency and pumping power of heat pipe solar collector (HPSC). The volume flow rate of the working fluid was 5, 8, 11, and 14 L/min. Also, mass concentration of nanoparticles was 0.5 and 1.167 g/L. Co-precipitation technique was employed to prepare CuO, Al2O3, and MgO nanoparticles. The optical and structural characterization of the nanostructure were considered by using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and UV-visible analysis. The thermal performance of the HPSC using metal oxide nanofluids and water was compared with the volume flow rate that varied from 5 to 14 L/min. It was observed that nanofluids improved the collector efficiency between 9 and 20% compared with deionized water. The present results revealed that the maximum efficiency was found to be 83% for a mass concentration of 1.167 g/L of CuO nanofluids and volume flow rate of 14 L/min. The HPSC efficiency shows better improvement with the increasing mass concentration of metal oxide nanoparticles and volume flow rate. Also, the increase rate of the pumping power and pressure drop is less than 0.9% for all of the nanofluids that were used as the working fluids. Results showed that the metal oxide nanofluids are appropriate for increasing the efficiency of HPSC.

Influence of Relative Humidity on Germination and Metal Accumulation in Vigna radiata Exposed to Metal-based Nanoparticles

The effect of single (0.1, 1, and 10 mg L−1) and binary mixtures (0.1 + 0.1, 1 + 1, and 10 + 10 mg L−1) of metal-based nanoparticles (CdO and CuO) on the germination of Vigna radiata was studied under two humidity ranges (70% and 80%). Filter paper-based tests were conducted. The surface-sterilized seeds were exposed to CdO and CuO under controlled environmental conditions (70% and 80% humidity at 35 °C). Germination rates were scored after 24 h and 48 h. The accumulation of metals was tested in seedlings after 48 h using inductively coupled plasma mass spectrometry. Compared with 70% humidity, the germination rate was higher under 80% humidity in all tested conditions. The germination rate of the CdO + CuO treatment was less than that of the single metal exposure under both humidities (70% and 80%) at 48 h. By two-way analysis of variance (ANOVA), we found that germination was greatly influenced by humidity. The accumulation of metal was higher in the CuO test than in the CdO test. Metal accumulation was concentration and humidity dependent, except for Cd accumulation in the CdO + CuO treatment. Here we show that the germination of seeds depends on the humidity and concentration of metal oxide nanoparticles. Understanding these strategies in seeds might help to avoid environmental and chemical stress and improve crop yield.

NEW DATA ON THE QUESTION OF INFORMATIVENESS OF EXPERIMENTS ON CELL CULTURES FOR ASSESSMENT OF COMPARATIVE AND COMBINED TOXICITY OF METAL OXIDE NANOPARTICLES

Isolated and combined damaging effects of PbO and CuO nanoparticles have been estimated on an established line of human fibroblasts using three different cytotoxicity indices based on reduction in: (a) the cellular dehydrogenase activity (MTT Assay), (b) the ATP content (Luminescent Cell Viability Assay), (c) the cellular proliferation, viability, spreading, and attachment to substrate evaluated integrally by continuous impedance-based measurement of the Normalized Cell Index. For all these indicators a clear dependence of cell damage on concentration of metal oxide nanoparticles has been demonstrated for both types of metal oxide nanoparticles, which is adequately described by the hyperbolic function, while at the same level of exposure the quantitative characteristics of cytotoxicity of PbO-NPs in comparison with CuO-NPs are similar. The latter was previously observed in the subchronic experiment on rats. The combined in vitro cytotoxicity of nanoparticles has been also described mathematically using the response surface construction methodology and found to be ambiguous, which is also consistent with the conclusions from the experiment on rats with the same nanoparticles.

Dielectric properties of zeolite based metal oxide nanocomposites

Metal oxide/ZSM-5 composites are developed and dielectric properties are studied. The dielectric properties of composites depend on type and concentration of metal oxide nanoparticles. All composites show higher dielectric permittivities than pure ZSM-5 zeolite. The composites show a trend of gradual decrease in dielectric constant with increase in metal oxide content. The highest dielectric constant values are observed for 25% ZnO, TiO2 and CuO metal oxide fillers. The dissipation factors are also found to exhibit low values. The ac conductivity remains constant in low frequency region and increases linearly at high frequencies. CuO blended composites depict extremely high dielectric values.

Structural characterization, material properties and sensor application study of in situ polymerized polypyrrole/silver doped titanium dioxide nanocomposites

Polypyrrole (PPy)/silver doped titanium dioxide (Ag-TiO2) nanocomposites were prepared using simple and inexpensive in situ chemical oxidative polymerisation. The nanocomposites were characterised by Fourier transform infrared (FTIR), UV-Vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), alternating current (AC) and direct current (DC) conductivity measurements. Furthermore, the ammonia gas sensing properties of PPy and its nanocomposites were explored thoroughly. The FTIR spectrum confirmed the formation of a polymer nanocomposite when the characteristic bands of the PPy shifted to a lower wavenumber region. The UV-Vis spectrum revealed that all the absorption peaks of the composite were shifted to a higher wavelength in comparison with PPy. The shifts in absorption peaks were due to the strong interfacial interaction between the nanoparticles and polymer chain. SEM images showed that the nanoparticles were well shaped spherical particles with the uniform dispersion in the PPy. XRD results revealed that the crystallinity of the nanocomposite increased with an increase in concentration of nanoparticles. TGA analysis showed that the thermal stability of the nanocomposite was enhanced compared to pure PPy. From the DSC analysis, it was clear that the glass transition temperature of the nanocomposite increased when the concentration of metal oxide nanoparticles was augmented. The fabricated composites showed excellent sensitivity and fast response to ammonia gas at room temperature. The electrical conductivity, dielectric constant and dissipation factor of the nanocomposites significantly increased with an increase in the concentration of metal oxide nanoparticles in the PPy matrix.

Are in vivo and in vitro assessments of comparative and combined toxicity of the same metallic nanoparticles compatible, or contradictory, or both? A juxtaposition of data obtained in respective experiments with NiO and Mn3O4 nanoparticles

Comparative and combined damaging effects of NiO and Mn3O4 nanoparticles were estimated on cultures of several established human cell lines.The cytotoxicity indices used were: (a) reduction in cellular dehydrogenase activity, (b) decrease in the ATP-content, (c) for SH-SY5Y cells also decrease in the tyrosine hydroxylase content. The combined cytotoxicity was modeled using the Response Surface Methodology.When assessing the stability of metal oxide nanoparticles (MeO-NPs) in cultural media used by us, we found that the addition of the fetal bovine serum (FBS) to them renders NiO-NPs and, to even greater extent, Mn3O4-NPs exponentially slow soluble while without FBS their dissolution was virtually undetectable. At the same time, sedimentation of these MeO-NPs noticeably slowed down in the presence of the same FBS.We have found dependence of cell damage on concentrations of MeO-NPs and higher cytotoxicity of Mn3O4-NP compared with NiO-NP. Thus, comparative assessment of the NPs unspecific toxicity obtained in our animal experiments was reproduced by the “in vitro” tests. However, with respect to manganese-specific brain damage “in vivo” discovered previously, present experiments on neurons “in vitro” showed only a certain enhancing effect of Mn3O4-NP on the action of NiO-NP, but the role of NiO-NP in the combination prevailed.

Fabrication and characterization of biopolymer nanocomposites from natural resource materials

In this study, nanocomposites of cashew tree gum (CTG) encapsulated nano‐magnetite (Fe3O4) was prepared and characterized by FTIR, UV–visible, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magnetic and conductivity measurements. The characteristic absorption peaks in FTIR and UV–vis spectra of CTG was found to be shifted to higher wave numbers in CTG/Fe3O4 composite, which is due to the intermolecular interaction between nanoparticles and the CTG. The XRD patterns indicated that amorphous region of gum was decreased by the addition of metal oxide nanoparticles. SEM images show that nano‐Fe3O4 was uniformly dispersed in the cashew gum segments. DSC analysis revealed that the glass transition temperature and melting behavior of composites were higher than those of the pure gum. TGA results indicated that the thermal decomposition temperature of the composite increases with the increase in concentration of metal oxide nanoparticles. The magnetic properties studied by a vibrating sample magnetometer indicate that electromagnetism of CTG/Fe3O4 nanocomposites were superparamagnetic. The values of saturation of magnetization (Ms) and remanence (Mr) increases, while the coercivity (Hc) decreased with increase in Fe3O4 content in the composite. The AC electrical conductivity of the nanocomposites was significantly increased with the increase in Fe3O4 content in the nanocomposite. Due to the ordered structure of polymer composite, the dielectric constant and dielectric loss tangent (tan δ) of nanocomposites were also increased with increase in the concentration of nanoparticles. POLYM. COMPOS., 38:E66–E73, 2017. © 2016 Society of Plastics Engineers

Synthesis, characterization, and properties of cashew gum graft poly(acrylamide)/magnetite nanocomposites

ABSTRACTGraft copolymer nanocomposites based on cashew gum and poly(acrylamide) with different concentrations of nano‐iron‐oxide particles (Fe3O4) have been prepared by an in situ polymerization method. The characterization of graft copolymer composite was carried out by FTIR, UV, XRD, SEM, DSC, and TGA, electrical conductivity, and magnetic property [vibrational sample magnetometer (VSM)] measurements. The shift in the spectrum of UV and FTIR peaks shows the intermolecular interaction between metal oxide nanoparticles and the graft copolymer system. The spherically shaped particles observed from the SEM images clearly indicating the uniform dispersion of nanoparticles within the graft copolymer chain. The XRD studies revealed that the amorphous nature of the graft copolymer decreases by the addition of Fe3O4 nanoparticles. The glass transition temperature studied from DSC increases with increase in concentration of metal oxide nanoparticles. Thermal stability of composite was higher than the pure graft copolymer and thermal stability increases with increase in content of nanoparticles. Electrical properties such as AC conductivity and dielectric properties of the composites increased with increase in concentration of metal oxide nanoparticles. The magnetic property of graft copolymer nanocomposites shows ferromagnetic and supermagnetism and the saturation of magnetism linearly increased with increasing the Fe3O4 content in the polymer composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43496.

Heat transfer performance of silver/water nanofluid in a solar flat-plate collector

An experimental study is carried out to investigate the heat transfer characteristics of silver/water nanofluid in a solar flatplate collector. The solar radiation heat flux varies between 800 W/m2and 1000W/m2, and the particle concentration varies between 0.01%, 0.03%, and 0.04%. The fluid Reynolds number varies from 5000 to 25000. The influence of radiation heat flux, mass flow rate of nanofluid, inlet temperature into the solar collector, and volume concentration of the particle on the convective heat transfer coefficient and the collector efficiency are studied. Both parameters increase with increase in the particle volume concentration and flow rate. The maximum percentage increase obtained in the convective heat transfer coefficient is 18.4% for the 0.04% volume concentration at a Reynolds number of 25000. An increase in the performance of nanofluid is also witnessed when compared to the base fluid, which has a strong dependency on volume concentration and mass flow rate. MgO. The nanofluid achieved a 3°C temperature difference during the daytime peak solar radiation compared with the base fluids. With a concentration of 0.2% ZnO, a temperature difference of 2.55°C for daytime and 1°C for nighttime was reached, and this was determined to be the most attractive option for solar energy utilization. Yousefi et al. [15] witnessed a 28% performance improvement in a flat-plate collector when it was operated with water-Al2O nanofluids. Tyagi [16] theoretically compared the conventional flat-plate collector with a direct absorption solar collector (DAC) and observed the former to be 10% more efficient. Otanicar [17] studied the conomic and environmental influences of using nanofluids to enhance solar collector efficiency with conventional solar collectors. Dongxiao et al. [18] presented excellent photothermal properties of carbon-black aqueous nanofluids at highvolume fractions. Further work on nanofluids’ application to direct solar absorption has been carried out by Lijuan Mu [19] using a custom-made direct solar absorber. The radiative properties of several nanofluids are tested for the highest temperature difference across the heat exchangers. Based on the above-mentioned review of the literature, it has been clearly observed that most of the previous studies on solar flat-plate collectors were conducted using metal oxide nanoparticles in relatively high concentrations. These high concentrations of metal oxide nanoparticles cause a higher pressure drop that then requires a higher pumping power. Since a limited number of studies exists in the literature with respect to pure metal nanoparticles, it is recommended to study the heat transfer characteristics of pure metal nanoparticles with relatively low concentrations (<1%) by volume and high thermal conductivity compared with metal oxides. Therefore, in the present study, the efficiency of a solar flat-plate collector is studied with a low particle volume concentration of less than 0.04% silver-water nanofluid. These experiments are conducted for a solar radiation flux ranging from 800 W/m2 to 1000 W/m2, and the Reynolds number varying from 5000 to 25000. The effect of radiative heat flux, mass flow rate, inlet temperature, and volume concentration on the convective heat transfer coefficient and the collector efficiency are studied. The tailormade setup for a collector area is 2.4m2 and the collector plate is made of nine parallel copper strips

Imaging interactions of metal oxide nanoparticles with macrophage cells by ultra-high resolution scanning electron microscopy techniques.

Use of engineered metal oxide nanoparticles in a plethora of biological applications and custom products has warned about some possible dose-dependent cytotoxic effects. Macrophages are key components of the innate immune system used to study possible toxic effects and internalization of different nanoparticulate materials. In this work, ultra-high resolution field emission scanning electron microscopy (FE-SEM) was used to offer new insights into the dynamical processes of interaction of nanomaterials with macrophage cells dosed with different concentrations of metal oxide nanoparticles (CeO(2), TiO(2) and ZnO). The versatility of FE-SEM has allowed obtaining a detailed characterization of processes of adsorption and endocytosis of nanoparticles, by using advanced analytical and imaging techniques on complete unstained uncoated cells, including secondary electron imaging, high-sensitive backscattered electron imaging, X-ray microanalysis and stereoimaging. Low voltage BF/DF-STEM confirmed nanoparticle adsorption and internalization into endosomes of CeO(2) and TiO(2), whereas ZnO develop apoptosis after 24 h of interaction caused by dissolution and invasion of cell nucleus. Ultra-high resolution scanning electron microscopy techniques provided new insights into interactions of inorganic nanoparticles with macrophage cells with high spatial resolution.

Microbial toxicity of metal oxide nanoparticles (CuO, NiO, ZnO, and Sb2O3) to Escherichia coli, Bacillus subtilis, and Streptococcus aureus

In this study, the microbial toxicities of metal oxide nanoparticles were evaluated for Escherichia coli, Bacillus subtilis, and Streptococcus aureus in laboratory experiments. The nanoparticles tested were CuO, NiO, ZnO, and Sb2O3. The metal oxide nanoparticles were dispersed thoroughly in a culture medium, and the microorganisms were cultivated on Luria–Bertani agar plates containing different concentrations of metal oxide nanoparticles. The bacteria were counted in terms of colony forming units (CFU). The CFU was reduced in a culture medium containing metal oxide NP, and the dose–response relationship was characterized. CuO nanoparticles were found to be the most toxic among the tested nanoparticles, followed by ZnO (except S. aureus), NiO, and Sb2O3 nanoparticles. We determined that the intrinsic toxic properties of heavy metals are also associated with the toxicity of metal oxide nanoparticles. Ion toxicity was also evaluated to determine the effects of metal ions dissolved from metal oxide NPs, and the toxicity induced from the dissolved ions was determined to be negligible herein. To the best of our knowledge, this is the first study of the toxicity of NiO and Sb2O3 NPs on microorganisms. We also discuss the implications of our findings regarding the effects of the intrinsic toxic properties of heavy metals, and concluded that the apparent toxicities of metal oxide NPs can largely be understood as a matter of particle toxicity.