High Nanoparticle Concentrations Research Articles

Fluorescence quenching and related interactions among globular proteins (BSA and lysozyme) in presence of titanium dioxide nanoparticles

In recent days, nanoparticles (NPs) are used in various industries, and their release in the environment is a matter of concern for both environment and living systems. It is, therefore, necessary to study the protein-NPs systems for better understanding the impacts of NPs on living organisms. In this article, the structure, optical properties, and related conformation of the globular proteins, bovine serum albumin and lysozyme, are explored in the presence of titanium dioxide nanoparticles. The interactions are analyzed by fluorescence quenching and Fourier transform infrared spectroscopy techniques. In the presence of NPs, the fluorescence quenching of the proteins is observed, and it is found that the mixture of both static and dynamic quenching is present, but the contribution from static is more than dynamic. Mostly the higher order complex formation and excited state quenching at higher NPs concentration are responsible for the fluorescence quenching. The interaction is also studied in different pH environments and depending upon the isoelectric points of the respective proteins. With fluorescence quenching, a substantial amount of red-shift of protein emission is also observed in the presence of the quencher. The change in the microenvironment of the tryptophan residues may be responsible for this type of shift. • Interaction between globular proteins and titanium oxide nanoparticles (TiO 2 NPs) is studied. • Fluorescence quenching of globular proteins (BSA and lysozyme) is observed in presence of TiO 2 NPs. • Higher order complex formation and excited state quenching play the major role in quenching. • The interaction is pH dependent and relatively more at lower pH. • Red-shift in protein emission was observed due to change in microenvironment induced by TiO 2 NPs.

Entomotoxicity of TiO2 and ZnO Nanoparticles Against Adults Tribolium Castaneum (Herbest) (Coleoptera: Tenebrionidae)

The red flour beetle Tribolium castaneum is one of the common pests of stored grains distributed worldwide. In this study, testing the effect of TiO2 and ZnO nanoparticles as insecticides on adults of T. castaneum was achieved. Results showed that the high concentration of TiO2 and ZnO nanoparticles recorded high cumulative mortality of the adult insects after exposure time 1, 3, and 5 days from treatments 15.30, 23.57, and 29.85% respectively of TiO2 nanoparticles compared with 20.42, 27.08, and 33.96 % respectively of ZnO nanoparticles. The result showed that TiO2 and ZnO nanoparticles are effective in controlling and can be introduced in the future in integrated pest management of T. castaneum.

Development of a Strategy for Enhancing the Biomass Growth and Lipid Accumulation of Chlorella sp. UJ-3 Using Magnetic Fe3O4 Nanoparticles.

In this study, magnetic Fe3O4 nanoparticles (NPs) were used as an effective enhancer to increase the biomass and total lipid production of Chlorella sp. UJ-3. It was found that the biomass of algal cells increased significantly when they were exposed to low concentrations of Fe3O4 NPs (20 mg/L), while the best total lipid content of algal cells was achieved when they were exposed to high concentrations of Fe3O4 NPs (100 mg/L). Therefore, we established a strategy to promote the growth and lipid accumulation of microalgae by initially exposing the algal cells to low concentrations of Fe3O4 NPs and then treating them with an increased concentration of Fe3O4 NPs after 12 days of culture. For this strategy, the biomass and total lipid production of algal cells increased by 50% and 108.7%, respectively, compared to the untreated control. The increase in lipid production and change in the fatty acid composition of Chlorella cells were found to help them to cope with the increased number of reactive oxygen species produced due to oxidative stress in alga cells after the addition of Fe3O4 NPs. This study provided a highly efficient way to improve the lipid production of microalgae using nanoparticles.

Study on Dispersion Stability and Friction Characteristics of C60 Nanomicrosphere Lubricating Additives for Improving Cutting Conditions in Manufacturing Process

Antifriction lubrication is an important research hotspot in the manufacturing field. A high-performance lubricating additive is of great significance for condition monitoring in the metal cutting process system. To improve cutting conditions in manufacturing process, we study the dispersion stability and tribological properties of fullerene nanoparticles in HM32 antiwear lubricating fluid. Fullerene nanoparticles are fully integrated into HM32 antiwear lubricating fluid by electromagnetic stirring and ultrasonic oscillation. The dispersion stability of fullerene nanoparticles in HM32 antiwear lubricating fluid was comprehensively studied by microscope scanning experiment, static sedimentation experiment, and absorption experiment. The four-ball friction experiment was operated to investigate the extreme pressure property and tribological property of lubricating fluids with fullerene concentration ranging from 100 ppm to 1000 ppm. The results show that fullerene nanoparticle can significantly improve the extreme pressure property and wear resistance of HM32 basic lubricating fluid. Meanwhile, we found that an excessively high concentration of fullerene nanoparticles will increase the friction and wear of the four-ball friction pair. The best concentration of fullerene nanoparticles is 200 ppm. When the fullerene concentration reaches 200 ppm, the maximum nonsintering load is significantly increased, and the friction coefficient and the steel ball wear scar diameter are significantly reduced.

STRUCTURE AND ELECTROPHYSICAL PROPERTIES OF PVDF+PbS/CdS NANOCOMPOSITES

In the given paper were investigated structure and electrophysical properties of PVDF+PbS/CdS nanocomposites. Distribution and the size of PbS and CdS nanoparticles in the polymer matrix has been studied by scanning electron microscopy (JEOL JSM-7600 F). The structure of the nanocomposite samples was investigated by the X-ray diffraction spectroscopy. The dependence of dielectric permittivity at frequency and temperature was investigated. It was shown that the dielectric permittivity of PVDF+PbS/CdS nanocomposite samples was increase in small nanoparticles content. Further increase in the concentration of the filler leads to decrease in the dielectric permittivity. The subsequent decrease in dielectric permittivity at higher nanoparticles content can be explained by the increase in defects in the structure of the nanocomposite.

Femtosecond laser trapping nanoprinting of silver micro/nanostructures

In this paper, silver micro/nanostructures composed of sintered nanoparticles were printed by capturing silver nanoparticles in water with 800 nm femtosecond laser trapping. Relationships of laser power, scanning speed, nanoparticle concentration, and the width and morphology of fabricated silver wire were systematically investigated. It is found that low scanning speed and high nanoparticle concentration favor the printing of silver wire with good morphology. A silver wire with width of 305 nm was printed. Electrical resistivities of printed wires are about 24 times that of bulk silver. Silver grid structures and dot arrays were printed by using this technology. Several three-dimensional silver cuboid structures were also printed. This work provides a protocol for printing of three-dimensional metallic micro/nanostructures using laser trapping. These printed structures have great application prospects in metamaterials, flexible electronics, and SERS.

Effects of Surfactant and Hydrophobic Nanoparticles on the Crude Oil-Water Interfacial Tension

Surfactants and nanoparticles play crucial roles in controlling the oil-water interfacial phenomenon. The natural oil-wet mineral nanoparticles that exist in crude oil could remarkably affect water-oil interfacial characteristics. Most of recent studies focus on the effect of hydrophilic nanoparticles dispersed in water on the oil-water interfacial phenomenon for the nanoparticle enhanced oil recovery. However, studies of the impact of the oil-wet nanoparticles existed in crude oil on interfacial behaviour are rare. In this study, the impacts of Span 80 surfactant and hydrophobic SiO2 nanoparticles on the crude oil-water interfacial characteristics were studied by measuring the dynamic and equilibrium crude oil-water interfacial tensions. The results show the existence of nanoparticles leading to higher crude oil-water interfacial tensions than those without nanoparticles at low surfactant concentrations below 2000 ppm. At a Span 80 surfactant concentration of 1000 ppm, the increase of interfacial tension caused by nanoparticles is largest, which is around 8.6 mN/m. For high Span 80 surfactant concentrations, the less significant impact of nanoparticles on the crude oil-water interfacial tension is obtained. The effect of nanoparticle concentration on the crude oil-water interfacial tension was also investigated in the existence of surfactant. The data indicates the less significant influence of nanoparticles on the crude oil-water interfacial tension at high nanoparticle concentration in the presence of Span 80 surfactant. This study confirms the influences of nanoparticle-surfactant interaction and competitive surfactant molecule adsorption on the nanoparticles surfaces and the crude oil-water interface.

RETRACTED: A study of a computational BVP for heat transfer and friction drag in magnetohydrodynamics viscous flow of a nanofluid subject to the curved surface

The ongoing work investigates the features of Joule heating and convective condition over a magnetohydrodynamic stagnation point flow of [Formula: see text] nanofluid moving across a curved surface. Moreover, mass suction is supposed through the stretching/shrinking surface. The initially developed model of partial differential equations is transformed into the ordinary ones assisted by suitable similarity variables. Subsequently, the ultimate nonlinear model of ordinary differential equations is solved with the help of a built-in function bvp4c package in MATLAB. Several graphical results are plotted to see the influence of various dimensionless parameters over the velocity, temperature, heat transfer, and friction drag. We found that there exists an escalation in temperature with increasing values of curvature, Eckert number, Hartmann number, and Biot number; however, the velocity profile declines with large curvature, ratio parameter, and high concentration of nanoparticles. It is also important to note that the friction drag rises with the mass suction, and reduces with vast curvature, whereas the rate of heat transfer improves with suction and Biot number but lowers with Eckert number and Hartmann number.

Targeting multiple mediators of sepsis using multifunctional tannic acid-Zn2+-gentamicin nanoparticles

Targeting multiple mediators of sepsis using multifunctional tannic acid-Zn2+-gentamicin nanoparticles

Multifunctionality of Nanosized Calcium Apatite Dual-Doped with Li+/Eu3+ Ions Related to Cell Culture Studies and Cytotoxicity Evaluation In Vitro.

Li+/Eu3+ dual-doped calcium apatite analogues were fabricated using a microwave stimulated hydrothermal technique. XRPD, FT-IR, micro-Raman spectroscopy, TEM and SAED measurements indicated that obtained apatites are single-phased, crystallize with a hexagonal structure, have similar morphology and nanometric size as well as show red luminescence. Lithium effectively modifies the local symmetry of optical active sites and, thus, affects the emission efficiency. Moreover, the hydrodynamic size and surface charge of the nanoparticles have been extensively studied. The protein adsorption (lysozyme, LSZ; bovine serum albumin, BSA) on the nanoparticle surface depended on the type of cationic dopant (Li+, Eu3+) and anionic group (OH−, Cl−, F−) of the apatite matrix. Interaction with LSZ resulted in a positive zeta potential, and the nanoparticles had the lowest hydrodynamic size in this protein medium. The cytotoxicity assessment was carried out on the human osteosarcoma cell line (U2OS), murine macrophages (J774.E), as well as human red blood cells (RBCs). The studied apatites were not cytotoxic to RBCs and J774.E cells; however, at higher concentrations of nanoparticles, cytotoxicity was observed against the U2OS cell line. No antimicrobial activity was detected against Gram-negative bacteria with one exception for P. aeruginosa treated with Li+-doped fluorapatite.

Fast Fluorescence Titration Quantification of Plasmid DNA with DNA Attractive Magnetic Nanoparticles.

Fluorescence titration using magnetic nanoparticles (FTMN) was performed as a rapid, inexpensive, and simple method for quantifying the amount of fluorophore-intercalated plasmid DNA on these DNA attractive nanoparticles. Binding of the propidium iodide (PI)-intercalated DNA (PI/DNA) to polyethylenimine (PEI)-coated monodisperse iron oxide magnetic nanoparticles (PEI-MNs) was confirmed with transmission electron microscopy after the two species were mixed in water for less than a minute. The amount of DNA on PEI-MNs in aqueous solution, however, could not be easily determined using direct fluorescence measurements due to strong scattering by aggregated MNs, especially at high nanoparticle concentrations. Instead, fluorescence measurements were taken immediately after the solution of PI/DNA and PEI-MN mixtures was treated with a magnet to pull the PEI-MNs out of the solution. The detected fluorescence signal of the remaining free PI/DNA in the solution decreased as the concentration of PEI-MNs in the pre-treated solutions increased, resulting in a titration curve, which was used to determine the amount of DNA on MNs, the dissociation constant, and binding energy after the concentration of PEI-MNs was calibrated with microwave-plasma atomic emission spectroscopy. Quantitative polymerase chain reaction was used to understand the binding of DNA to MNs and to measure the amount of free PI/DNA in solution, and the results were similar to those obtained with the FTMN method.

A Monte Carlo Study on Dose Enhancement in the Presence of Nanoparticles by Photon Source: A Comparison between Various Concentration and Material of Nanoparticles

Purpose: Recently, the application of high atomic number nanoparticles is suggested in the field of radiotherapy to improve physical dose enhancement and hence treatment efficiency. Several factors such as concentration and material of nanoparticles and energy of beam define the amount of dose enhancement in the target in the presence of nanoparticles. Materials and Methods: In this approach, a spherical cell was simulated through the Geant4 Monte Carlo toolkit which contained a nucleus and nanoparticles distributed through the cell. To investigate the effect of the concentration of nanoparticles on the deposited dose, it ranged from 3 mg/g to 30 mg/g for different materials like gold, silver, gadolinium, and platinum. Also, various mono-energetic photon beams included low and high energy sources were applied. Results: The results proved that as the concentration increased, the Dose Enhancement Factor (DEF) enlarged. Overall, almost for all energy and material that were used in this study, the maximum of DEF values occurred in the concentration of 30 mg/g. Moreover, lower energy sources presented higher DEF compared to other sources. The results indicated that the highest amount of DEF transpired for 35 keV photon beams equal to 14.67. Also, the K-edge energy of each material affects DEF values. Conclusion: To obtain a better outcome in the use of nanoparticles in combination with radiotherapy, a higher concentration of nanoparticles and low-energy photons should be considered to optimize the DEF and thus the treatment ratio.

UV Light-Activated GdYVO4:Eu3+ Nanoparticles Induce Reactive Oxygen Species Generation in Leukocytes Without Affecting Erythrocytes In Vitro.

Nanoparticles (NPs) have been reported to be promising enhancement agents for radiation therapy. The aim of the study was to assess the cytotoxicity of UV non-treated and UV pretreated GdYVO4:Eu3+ nanoparticles against erythrocytes and leukocytes by detecting eryptosis and reactive oxygen species (ROS) generation. Levels of intracellular ROS in erythrocytes and leukocytes using a ROS-sensitive dye 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA), as well as eryptosis rate utilizing annexin V staining, following direct exposure to UV-activated and nonactivated NPs were detected by flow cytometry. Blood cells were collected from 9 intact WAG rats. Neither the UV light-untreated GdYVO4:Eu3+ NPs nor the treated ones promoted eryptosis and ROS generation in erythrocytes. Low concentrations of UV light-untreated NPs did not induce oxidative stress in leukocytes, evidenced by unaffected intracellular ROS levels. UV light treatment grants prooxidant properties to NPs, confirmed by NP-induced ROS overproduction in leukocytes. High concentrations of both UV light-treated and untreated NPs altered the redox state of leukocytes. UV light treatment imparts prooxidant properties to GdYVO4:Eu3+ NPs, making them promising radiosensitizing agents in cancer radiation therapy.

Photocatalytic pathway on the degradation of methylene blue from aqueous solutions using magnetite nanoparticles

In this work, magnetite nanoparticles, synthesized by the sol-gel citrate-nitrate method, were applied as precursors for methylene blue degradation in a simulated aqueous solution. The degradation pathway analysis was performed through a 22 experimental design, which includes nanoparticles and H2O2 concentration as variables. Statistical analysis showed that the nanoparticle concentration is the parameter with the greatest significance. The experiment conducted with the highest concentrations of nanoparticles and H2O2 (2250 mg/L and 130 g/L, respectively) obtained the most effective color removal (93.4%) in 210 min. Time-depended photodegradation was monitored by liquid chromatography coupled to tandem mass spectrometry. In addition, it was possible to suggest that different reaction mechanisms, such as Fenton reaction, photocatalysis, and adsorption, may contribute to the decrease in the concentration of methylene blue in the solution. The dye degradation kinetic data were adjusted by the adapted models of pseudo-first-order and pseudo-second-order. The results showed that the presence of the optimized magnetic nanoparticles powder led to a decrease of 148 times in the degradation concentration of methylene blue after 210 min of irradiation. In addition, the analysis of decomposition products showed that mineralization had advanced extensively to simple organic acids, showing the excellent performance of this photocatalytic system.

In Situ Biosynthesis of a Metal Nanoparticle Encapsulated in Alginate Gel for Imageable Drug-Delivery System.

Development of drug-delivery systems that allow simultaneous in vivo imaging has gained much interest. We report a novel strategy to encapsulate metal nanoparticles (NPs) within alginate gel for in vivo imaging. The cell lysate of recombinant Escherichia coli strain, expressing Arabidopsis thaliana phytochelatin synthase and Pseudomonas putida metallothionein genes, was encapsulated within the alginate gel. Incubation of alginate gel with metal ion precursors followed by UV irradiation resulted in the synthesis of high concentrations of metal NPs, such as Au, Ag, CdSe, and EuSe NPs, within the gel. The alginate gel with metal NPs was used as a drug-delivery system by further co-encapsulating doxorubicin and rifampicin, the release of which was made to be pH-dependent. This system can be conveniently and safely used for in vitro and in vivo bioimaging, enabled by the metal NPs formed within the gel matrix without using toxic reducing reagents or surfactants.

Toxicity of a Binary Mixture of TiO2 and Imidacloprid Applied to Chlorella vulgaris

Nanoparticles have applications in various fields such as manufacturing and materials synthesis, the environment, electronics, energy harvesting, and medicine. Besides many applications of nanoparticles, further research is required for toxic environmental effect investigation. The toxic effect of titanium dioxide nanoparticles on the physiology of the green alga Chlorella vulgaris was studied with a widely used pesticide, imidacloprid (IMD). Chlorella vulgaris was exposed for 120 h in Bold’s basal medium to different toxic compounds, such as (i) a high concentration of TiO2 nanoparticles, 150–2000 mg/L, usually optimised in the photocatalytic degradation of wastewater, (ii) an extremely toxic pesticide for the aquatic environment, imidacloprid, in concentrations ranging from 5 to 40 mg/L, (iii) TiO2 nanoparticles combined with imidacloprid, usually used in a photocatalytic system. The results show that the TiO2 nanoparticles and IMD inhibited Chlorella vulgaris cell growth and decreased the biovolume by approximately 80% when 2 g/L TiO2 was used, meaning that the cells devised a mechanism to cope with a potentially stressful situation; 120 h of Chlorella vulgaris exposure to 40 mg/L of IMD resulted in a 16% decreased cell diameter and a 41% decrease in cell volume relative to the control sample, associated with the toxic effect of pesticides on the cells. Our study confirms the toxicity of nanoparticles through algal growth inhibition with an effective concentration (EC50) value measured after 72 h of 388.14 mg/L for TiO2 and 13 mg/L for IMD in a single-toxic system. The EC50 of TiO2 slowly decreased from 258.42 to 311.11 mg/L when IMD from 5 to 20 mg/L was added to the binary-toxic system. The concentration of TiO2 in the binary-toxic system did not change the EC50 for IMD, and its value was 0.019 g/L. The photodegradation process of imidacloprid (range of 5–40 mg/L) was also investigated in the algal medium incubated with 150–600 mg/L of titanium dioxide.

Heat transfer potentials of ZnO/water nanofluid in free impingement jet

Heat transfer represented by jet impingement was considered due to the grown demand for such applications in the industry such as heat exchangers, metal cutting, and electronic's component cooling. Hence, ZnO/water nanofluid is embraced to enhance the heat exchanged by impinge nanofluid through a square jet. Five nanofluid were prepared thoroughly with different ZnO concentrations range of (0.1–0.5%) besides a plain de-ionized water for comparison. Validation was performed by comparing the outcome with comparable analogous studies and exhibited a content deviation. The parameter (H/Dh) which denotes the (exit of nozzle-to-hot plat spacing over the hydraulic jet diameter) was varied to be 2–8. The acquired results showed that the adoption of nanofluid in such an arrangement gives further magnification in heat transfer (Nu = 113.9%) at high Reynold's number and nanoparticle concentration (φ = 0.5%, Re = 17500, and H/Dh = 2). Whereas the minimum gained heat (Nu = 43.8%) was detected at nanoparticle concentration of (ɸ = 0.1%), Reynold's number of (Re = 5000), and H/Dh spacing of 8 respectively. It was found that applying excessive heat flux on the target plate causes rapid evaporation once the flow hits the surface plate, which leads to poor thermal performance. Eventually, the gained data were correlated and the empirical correlation is proposed.

Sealing Tröger base/ZIF-8 mixed matrix membranes defects for improved gas separation performance

Manufacturing defect-free mixed matrix membranes (MMMs) especially with high nanoparticle concentrations exceeding 40 wt% is still an ongoing challenge. Desired performance improvements are often unfulfilled in MMMs with high filler loading because nanoparticles with increasing contents are prone to aggregating, forming non-selective cavities, and deteriorating membrane's mechanical properties. To address this key issue, our work develops MMMs using Tröger base (TB) polymer with more hydrogen bond acceptors, polydopamine (PDA), and ZIF-8 fillers. The PDA modified ZIF-8 to create TB/ZIF-8 MMMs especially with high ZIF-8 loading over 40 wt% improves membrane mechanical properties and completely seals structural defectives to demonstrate encouraging gas selectivities. Hydrogen bonding between CN:NH and CN:OH groups within TB polymers and PDA enhances ZIF-8 interactions and reduces particle agglomeration within the polymer matrix. A TB/ZIF-8@PDA MMM containing 50 wt% ZIF-8 has H2 and CO2 permeabilities of 664.1 and 277.3 Barrer. Its ideal H2/CH4 and CO2/CH4 selectivities are 37.7 and 15.5, respectively. Equal molar CO2/CH4 mixed gas tests at various pressures demonstrate strong CO2 plasticization resistance and enhanced CO2/CH4 gas selectivity over ideal selectivity within the membranes. The combination of PDA modification technique on filler surfaces and a polymer with many hydrogen bonds acceptors is not only a feasible route to fabricate high filler loading MMMs with sealed defective structures, but also demonstrates positive impacts on membrane mechanical properties.

Optimum concentration of fly ash nanoparticles to stabilize CO2 foams for aquifer and soil remediation

Contamination caused by non-aqueous phase liquids (NAPLs) in aquifers and soil is an important challenge that requires effective remediation techniques. One potential approach is through the use of CO2 foams to displace NAPLs from permeable media. CO2 foams generated only by surfactants are not stable enough for the efficient removal of NAPLs contamination. This shortcoming may be alleviated via the use of nanoparticles (NPs)-surfactant mixtures as a stabilizing agent. This work focuses on the evaluation of the optimum concentration of fly ash nanoparticles for stabilizing CO2 foam with the combined action of the surfactant. The performance of this foam is evaluated in remediating a contaminated 41 mm × 36 mm surrogate permeable medium in a microfluidic device. Mixtures of fly ash, a by-product of coal-burning power plants, and alpha-olefin sulfonate (AOS) and lauramidopropyl betaine (LAPB) surfactants are used to generate stable foams. The results show that a 1000 mg/L AOS-LAPB surfactant solution along with 1000 mg/L of fly ash NPs produces the best performance. Formation of deposits in the matrix is observed. These deposits, which are more prominent at higher NP concentrations, appear to adversely affect displacement, displacement efficiency and remediation of the medium. This study demonstrates that using fly ash nanoparticles and optimizing their concentration can effectively stabilize CO2 foams and improve the displacement efficiency for aquifer and soil remediation.

An efficient nanoscale representative volume element simulation including graded interphase for tensile behavior of epoxy/silica nanocomposites

AbstractThe behavior of interphase‐particle adhesion and interphase region around the nanoparticles can significantly affect the stress distribution and mechanical properties of polymeric nanocomposites. In this study, the elastic modulus of epoxy/silica nanocomposites is analyzed using the finite element method and different mathematical models. A nanoscale representative volume element including graded interphase, homogenous interphase, and no interphase model is implemented. Furthermore, the effect of interfacial adhesion is also considered. The final elastic modulus was clearly affected by the interphase modulus, especially at higher nanoparticle content. Under imperfect interfacial bonding, the existence of an interphase region leads to a slight increase in modulus, and in the absence of that area, the elastic modulus decreases to 3.28 GPa. In perfect bonding models, stress transferred from the matrix to interphase and, then, to nanoparticle, which led to a significant increase in elastic modulus. Unlike the imperfect bonding, the maximum stress was located in the elements along to the loading direction. A maximum 26% increase in elastic modulus for perfect bonding/graded interphase model with 6.54 vol% of nanosilica particles compared to bulk epoxy was achieved. Finally, on comparing the FEM analysis and theoretical results with the experimental data, good agreement between obtained results was found.