Influence Of Nanoparticle Size Research Articles

Rheological behavior of water and ethylene glycol based nanofluids containing oxide nanoparticles

The paper presents the results of experimental study of rheological behavior of nanofluids based from consideration of several tens of nanofluids based on water, ethylene glycol and engine oil, containing particles of different oxides and diamond. The sizes of nanoparticles ranged from 5 to 150 nm, while their volume concentration ranged from 0.25 to 8%. At that, no dispersants were used when preparing tested nanofluids. It is shown that in some cases, when increasing nanoparticle concentration, rheological behavior of nanofluids becomes non-Newtonian and is well described by power-law fluid models or Herschel–Bulkley fluids. The influence of nanoparticle size and material, as well as the nature of the base fluid on the rheological behavior of nanofluids have been studied.

The influence of nanoparticle sizes on the X-ray excited luminescence intensity in YVO4:Eu

The influence of nanoparticle sizes on the X-ray excited luminescence intensity in YVO₄:Eu

Plasmon mediated enhancement and tuning of optical emission properties of two dimensional graphitic carbon nitride nanosheets

We demonstrate surface plasmon induced enhancement and tunablilty in optical emission properties of two dimensional graphitic carbon nitride (g-C3N4) nanosheets through the attachment of gold (Au) nanoparticles. Raman spectroscopy has revealed surface enhanced Raman scattering that arises due to the combined effect of the charge transfer process and localized surface plasmon induced enhancement in electromagnetic field, both occurring at the nanoparticle–nanosheet interface. Photoluminescence studies suggest that at an optimal concentration of nanoparticles, the emission intensity can be enhanced, which is maximum within the 500–525 nm region. Further, the fabricated electroluminescent devices reveal that the emission feature can be tuned from bluish-green to red (∼160 nm shift) upon attaching Au nanoparticles. We propose that the π*→π transition in g-C3N4 can trigger surface plasmon oscillation in Au, which subsequently increases the excitation process in the nanosheets and results in enhanced emission in the green region of the photoluminescence spectrum. On the other hand, electroluminescence of g-C3N4 can induce plasmon oscillation more efficiently and thus can lead to red emission from Au nanoparticles through the radiative damping of particle plasmons. The influence of nanoparticle size and coverage on the emission properties of two dimensional g-C3N4, nanosheets has also been studied in detail.

Chemical-Mechanical Impact of Nanoparticles and pH Effect of the Slurry on the CMP of the Selective Layer Surfaces

This paper provides a tribochemical study of the selective layer surface by chemical mechanical planarization (CMP). CMP is used to remove excess material obtained in the process of selective transfer. The paper aims at a better understanding of the planarization (polishing) and micromachining. The planarization becomes effective if the material removal rate (MRR) is optimal and the surface defects are minimal. The pH of the slurry plays a very important role in removing the selective layer by CMP, and hydrogen peroxide (H2O2) is the most common oxidizer used in CMP slurry. The purpose of this paper is the analysis of the pH effect on the etching rate (ER) and on the behavior of selective layer polishing by a constant concentration of H2O2 and the influence of nanoparticles size and concentration on selective layer surface CMP. The nanoparticle size used is 250 nm. The MRR results through CMP and ER have been shown to be influenced by the presence of oxides on the selective layer surface and have been found to vary with the slurry pH at constant H2O2 concentrations. The CMP slurry plays an important role in the CMP process performance and should be monitored for optimum results and minimal surface defects. The paper analyzes the impact of chemical-mechanical, inter-nanoparticle, and pad-nanoparticle-substrate interactions on CMP performance, taking into account the state of friction at the interface, by measuring the friction force. Selective layer CMP optimization studies were required to control the chemical and mechanical interactions at the interface between the slurry and the selective layer, the slurry chemistry, the properties, and the stability of the suspended abrasive nanoparticles.

Role of nanoparticle size in self-assemble processes of collagen for tissue engineering application

Nanoparticle mediated extracellular matrix may offer new and improved biomaterial to wound healing and tissue engineering applications. However, influence of nanoparticle size in extracellular matrix is still unclear. In this work, we synthesized different size of silver nanoparticles (AgNPs) comprising of 10nm, 35nm and 55nm using nutraceuticals (pectin) as reducing as well as stabilization agents through microwave irradiation method. Synthesized Ag-pectin nanoparticles were assimilated in the self-assemble process of collagen leading to fabricated collagen-Ag-pectin nanoparticle based scaffolds. Physico-chemical properties and biocompatibility of scaffolds were analyzed through FT-IR, SEM, DSC, mechanical strength analyzer, antibacterial activity and MTT assay. Our results suggested that 10nm sized Ag-pectin nanoparticles significantly increased the denaturation temperature (57.83°C) and mechanical strength (0.045MPa) in comparison with native collagen (50.29°C and 0.011MPa). The in vitro biocompatibility assay reveals that, collagen-Ag-pectin nanoparticle based scaffold provided higher antibacterial activity against to Gram positive and Gram negative as well as enhanced cell viability toward keratinocytes. This work opens up a possibility of employing the pectin caged silver nanoparticles to develop collagen-based nanoconstructs for biomedical applications.

Exploring the effect of nanoparticle size on the tribological properties of SiO2 / polyalkylene glycol nanofluid under different lubrication conditions

The influence of nanoparticle size on the tribological performances of the SiO2/PAG (Polyalkylene glycol) nanofluids under different lubricating condition were investigated. The silica nanoparticles displayed strong size-oriented adaptability to the lubricating conditions. Under lower frequency, the smaller nano-SiO2 could significantly improve the tribological performances, this is due to the formation of tribofilm with stronger intrinsic mechanical properties. However, the lubricating oil containing large nano-SiO2 showed better friction reducing property under higher frequency, it because the flow features of nanofluids has become a dominating factor affecting the tribological performance. What's more, compared with the nano-additives with the uniform size, the mixed nano-additives displayed better anti-wear and friction-reducing properties.

Insights into influence of nanoparticle size and metal–support interactions of Cu/ZnO catalysts on activity for furfural hydrogenation

Cu/ZnO catalysts primarily derived from aurichalcite with Cu/Zn = 0.4–1.1 (mol/mol) were prepared via “decreased pH” coprecipitation method and introduced in hydrogenation of furfural to furfuryl alcohol.

Targeting CD44 receptor-positive lung tumors using polysaccharide-based nanocarriers: Influence of nanoparticle size and administration route

New approaches that are more efficient and able to specifically reach lung tumors are needed. We developed new hyaluronan-based nanoparticles targeting CD44 receptors of two different sizes and compared their lung cancer cells targeting efficacy in vitro and in vivo. The nanoparticles’ cellular uptake was dose-dependent, and specific to hyaluronan receptors, particularly CD44. The binding and internalization differed according to nanoparticle size. In vivo biodistribution studies in two orthotopic lung tumor models showed that intrapulmonary nebulized nanoparticles accumulated in lungs, but not in the tumor nodules. In contrast, despite a significant liver capture, intravenous injection led to a better accumulation of the nanoparticles in the lung tumors compared with the surrounding healthy lung tissues. We demonstrated that the hyaluronan-based nanoparticles size plays significant role in cellular uptake and biodistribution. Small nanoparticles showed active targeting of CD44-overexpressing tumors, suggesting that they could be used as drug-delivery system. From the Clinical EditorCombating cancers remains an important goal in clinical medicine. In this study, the authors investigated the ability of two hyaluronan-based nanoparticles targeting CD44 receptors to home in on lung cancer cells in an in-vivo orthotropic model. The preferential uptake of smaller sized nanoparticles via intravenous route has further enhanced the existing knowledge of future drug designs.

Influence of Nanoparticle Size on Strain at the Core-Shell Interface

This work deals with the strain at the core-shell interface of Fe nanoparticles. Series of Fe nanoparticles with various mean diameters were prepared by precipitation in solid state in binary Cu-Fe alloy. Further, nanoparticles were isolated by dissolution of Cu matrix. High-energy X-ray diffraction (XRD) was used to probe structure of nanoparticles. XRD measurements suggest presence of the core-shell structure, where core and shell of the nanoparticles are formed of α-Fe and CuFe2O4 phase, respectively. Strains in core and shell were estimated as a function of nanoparticles size by Williamson-Hall method.

Influence of nanoparticle size and concentration on the electroactive phase content of PVDF in PVDF-CoFe2O4-based hybrid films

The synthesis and characterization of a new magnetoelectric polymer-oxide hybrid flexible class of materials were reported. It consists of ferrimagnetic and magnetostrictive cobalt ferrite (CoFe2O4) nanoparticles (NPs) dispersed into a ferroelectric and piezoelectric polyvinylidene fluoride beta-phase (β-PVDF) film. 6-nm and 9-nm sized CoFe2O4 NPs were produced by forced hydrolysis in polyol. β-PVDF films were obtained by drying a solution of PVDF/DMF at low temperature and by varying the amount and/or size of NPs inside them. The resulting composites were characterized by X-ray diffraction, transmission electron microscopy, infrared spectroscopy (attenuated total reflectance), differential scanning calorimetry and near-field microscopy (AFM). We clearly demonstrate that the presence of NPs leads to a decrease of the whole PVDF crystallinity within the hybrids but also that small variations of the size and amount of nanoparticles influenced the crystallization of the electroactive polar phase of PVDF. Higher percentages of polar PVDF phase were found in hybrid films processed at 80 °C and containing 9-nm CoFe2O4 NPs. Self-standing films of neat beta-phase PVDF (left) and PVDF–CoFe2O4 (15 wt.%) hybrid (right).

The influence of nanoparticle size on the mechanical properties of polymer nanocomposites and the associated interphase region: A multiscale approach

The characterization of the effective mechanical properties and geometry of the interphase in a heterogeneous material is a key issue for the design of polymer nanocomposites due to the dominant effect of the interphase on the overall behavior of the composites. In this study, molecular dynamics (MD) simulation and finite element (FE) analysis were integrated to develop a mechanics-based multiscale approach that can derive both the global stiffness and the local load transfer on the filler surface of the particulate nanocomposites. The unknown mechanical response and geometrical boundaries of the interphase (polymer networks adsorbed on the particle surface) are numerically obtained from a continuum model through the matching of homogenization and deformation energy to a full atomic molecular model. The equivalent continuum models given from the present multiscale method successfully represent the virial local stresses at both the interphase and matrix regions of the full-atomic model, as well as the particle size dependent stiffness of the nanocomposites. The proposed method is used to characterize the internal mechanical behavior of the intermediate media in terms of the nanoparticle size, and the nanophysics of the intermediate media are discussed in detail.

Influence of nanoparticle size, loading, and shape on the mechanical properties of polymer nanocomposites

We study the influence of spherical, triangular, and rod-like nanoparticles on the mechanical properties of a polymer nanocomposite (PNC), via coarse-grained molecular dynamics simulations. We focus on how the nanoparticle size, loading, mass, and shape influence the PNC's elastic modulus, stress at failure and resistance against cavity formation and growth, under external stress. We find that in the regime of strong polymer-nanoparticle interactions, the formation of a polymer network via temporary polymer-nanoparticle crosslinks has a predominant role on the PNC reinforcement. Spherical nanoparticles, whose size is comparable to that of the polymer monomers, are more effective at toughening the PNC than larger spherical particles. When comparing particles of spherical, triangular, and rod-like geometries, the rod-like nanoparticles emerge as the best PNC toughening agents.

Janus nanoparticles meet block copolymer scaffolds: on the influence of nanoparticle sizes

Janus nanoparticles possessing two spherical caps usually exhibit strong interfacial affinity, providing the possibility to create nanocomposites with controlled arrangement of nanoparticles. Here we extended the self-consistent field theory/density functional theory to study the position of the Janus nanoparticles in block copolymer scaffolds. The results demonstrated that the Janus nanoparticles exhibit a size-dependent distribution and orientation in block copolymer scaffolds. The smaller Janus nanoparticles are almost uniformly dispersed in the matrix, while the larger Janus nanoparticles are strongly attached to the interface. Meanwhile, the orientational order parameters of the Janus nanoparticles increase with increasing their sizes. The relative size of the spherical caps also shows a pronounced effect on the Janus nanoparticle distributions. As one of the spherical caps becomes smaller, the Janus nanoparticles partly migrate to the domains preferred by the larger spherical caps, but still remain strongly attached to the interface. The present study can provide an insight into the effect of size on the interfacial activity of the Janus nanoparticles, guiding the design of functional materials with advanced properties.

Effect of Particle Sizes on the Impedance of Electrospun Tungsten Oxide Nanofibers

Abstract This work presents the fabrication and the impedance spectroscopy characterization of WO3 nanofibers produced by an electrospinning technique. WO3 nanofibers consisting of various particle sizes are obtained by adjusting synthesis parameters. We highlight the influence of nanoparticle sizes on electrical resistances of electrospun nanofibers. It is found that nanofibers with small particle size have significantly high electrical resistance at the grain boundary. This is due to a significant spanning of the electron-depletion layer as compared to the size of the conduction channel in the structure. The grain boundary resistances of nanofibers with larger particle sizes have shown to be independent of the sizes of nanoparticles. To obtain ultra-sensitive gas sensors, producing nanofibers with restrictedly small particle sizes is a key, since large changes in electrical resistances can take place upon reacting with target gas molecules.

The influence of nanoparticle size and external AC magnetic field on heating ability

The effect of a two-way field containing a vertical and transverse AC magnetic field on heating abilities of Fe 3O 4 is investigated for magnetic nanoparticles with average sizes of 8.8 nm and 13.5 nm. The measurement shows that the heating abilities of our samples are size-dependent and field-dependent. We find that applying a two-way field can strongly increase the heating ability of larger-sized magnetic nanoparticles. That heating ability is different from the one under a single magnetic field. These large-sized Fe 3O 4 MNPs are thus suitable candidates for hyperthermia under a suitable two-way field.

Influence of Nanoparticle Size and Shape on Oligomer Formation of an Amyloidogenic Peptide.

Understanding the influence of macromolecular crowding and nanoparticles on the formation of in-register β-sheets, the primary structural component of amyloid fibrils, is a first step towards describing in vivo protein aggregation and interactions between synthetic materials and proteins. Using all atom molecular simulations in implicit solvent we illustrate the effects of nanoparticle size, shape, and volume fraction on oligomer formation of an amyloidogenic peptide from the transthyretin protein. Surprisingly, we find that inert spherical crowding particles destabilize in-register β-sheets formed by dimers while stabilizing β-sheets comprised of trimers and tetramers. As the radius of the nanoparticle increases crowding effects decrease, implying smaller crowding particles have the largest influence on the earliest amyloid species. We explain these results using a theory based on the depletion effect. Finally, we show that spherocylindrical crowders destabilize the ordered β-sheet dimer to a greater extent than spherical crowders, which underscores the influence of nanoparticle shape on protein aggregation.

Size Dependent Particle Toxicity in Drosophila

ABSTRACTNanotechnology, or the use of materials with one dimension less than 100nm, offers the ability to change particle reactivity by simply changing their size. This novel property of nanomaterials is used to create more effective medical treatments for cancer, tissue engineering and regenerative medicine, but the influence of nanoparticle size on environmental toxicity has not been thoroughly addressed to date. This study examines the influence of the size of silver particles on drosophila egg development by exposing their eggs to particle concentrations ranging from 10ppm-100 ppm of silver. Size, chemistry and agglomeration of the silver particles are evaluated using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS). This analysis confirmes individual silver particle size in the ranges of 20-30nm, 100nm and 500-1,200 nm with similar chemistry. DLS and TEM data also indicates agglomeration in water; with the TEM images showing individual particles in the correct size range, but the DLS z-average sizes of the silver nanoparticle are 782 ± 379 nm for the 20-30nm silver nanoparticles, 693 ± 114 nm for the 100nm silver nanoparticles and 508 ± 32 nm for the 500-1,200nm silver particles. Most importantly, here we show significantly more drosophila egg toxicity when exposed to larger, non-nanometer, silver particles. Upon exposure to silver nanoparticles sized 20-30nm, drosophila eggs do not exhibit a statistically significant (p<0.05) decrease in their likelihood to pupate, but eggs exposed to larger silver particles (500-1,200nm) are 91% (±18%) less likely to pupate. Exposure to silver nanoparticles reduces the percentage of pupa able to emerge as adults. At 10ppm of silver particle exposure, only 57% (± 48) of the pupa exposed to 20-30nm silver particles become adults whereas 89% (±25) of the control group becoem adults and 94%(±52) and 91%(±19) of the 500-1,200nm and 100nm group, respectively, reached adulthood. In this manner, this paper provides evidence that nanoscale silver particles (<100nm) are less toxic to drosophila eggs than conventional (>100nm) sized silver particles.

The influence of nanoparticle size on the magnetostrictive properties of cluster-assembled Tb–Fe nanofilms

The giant magnetostrictive Tb–Fe films assembled by nanoparticles have been prepared by the low energy cluster beam deposition. The dependence of the magnetostriction on the size of the nanoparticles is examined for the films. It is shown that the nanofilms have obtained higher saturation magnetostriction at the cluster size of 30 nm in average. The dependence of magnetostriction on particle size is ascribed to the degree of magnetic anisotropy which is related to the effective distance of exchange coupling between the adjacent Tb–Fe nanoparticles. This work demonstrates that the magnetostriction can be varied by tuning the particle size, which is important for control over the magnetostrictive properties of the films at nanoscale.

Influence of nanoparticle size on the pH-dependent structure of adsorbed proteins studied with quantitative localized surface plasmon spectroscopy

We have studied pH-dependent conformational transitions of Bovine Serum Albumin adsorbed onto different sizes of gold nanospheres. For larger spheres (D > 10 nm) there is evidence for a path-dependent extended state near pH 4, over a very small pH range. For smaller nanospheres (5 nm and 10 nm) the evidence for such a transition is either much weaker or completely suppressed. We suggest that the absence of the transition on small spheres is due to the fact that the protein adsorbed on such small spheres has already lost at least some of its tertiary structure. The results have important implications for the functionality of proteins adsorbed onto nanospheres or surfaces with nm scale roughness.

Cytochrome c on Silica Nanoparticles: Influence of Nanoparticle Size on Protein Structure, Stability, and Activity

The structure, thermodynamic and kinetic stability, and activity of cytochrome c (cyt c) on silica nanoparticles (SNPs) of different sizes have been studied. Adsorption of cyt c onto larger SNPs results in both greater disruption of the cyt c global structure and more significant changes of the local heme microenvironment than upon adsorption onto smaller SNPs. The disruption of the heme microenvironment leads to a more solvent-accessible protein active site, as suggested by Soret circular dichroism spectroscopy and through an increase in peroxidase activity as a function of increased SNP size. Similarly, the stability of cyt c decreases more dramatically upon adsorption onto larger SNPs. These results are consistent with changes in protein-nanoparticle interactions that depend on the size or surface curvature of the supporting nanostructure. This study provides further fundamental insights into the effects of nanoscale surfaces on adsorbed protein structure and function.