Properties Of Such Nanoparticles Research Articles

Nanoparticle induced fusion of lipid membranes.

Membrane fusion is crucial for infection of enveloped viruses, cellular transport, and drug delivery via liposomes. Nanoparticles can serve as fusogenic agents facilitating such membrane fusion for direct transmembrane transport. However, the underlying mechanisms of nanoparticle-induced fusion and the ideal properties of such nanoparticles remain largely unknown. Here, we used molecular dynamics simulations to investigate the efficacy of spheroidal nanoparticles with different size, prolateness, and ligand interaction strengths to enhance fusion between vesicles. By systematically varying nanoparticle properties, we identified how each parameter affects the fusion process and determined the optimal parameter range that promotes fusion. These findings provide valuable insights for the design and optimization of fusogenic nanoparticles with potential biotechnological and biomedical applications.

On the Application Potential of Chemically Tailored Metal Oxide and Higher Chalcogenide Nanoparticles for Nanoscale Resistive Switching Devices

Resistive switching (RS) for nonvolatile data storage is a highly relevant field of research. Up to now, RS devices are fabricated via semiconductor processing technologies. This poses the question of whether integration of chemically tailored nanoparticles, either consisting of valence change or phase change materials, can be integrated in nanoelectrode configurations in order to explore their functionality for RS applications. This review discusses the RS properties of such nanoparticles by means of selected examples of both nanoparticle assemblies as well as on the individual particle level. Although this field of research is rather unexplored, it becomes evident that chemically tailored nanoparticles bear great potential for RS applications.

Surface functionalization of bamboo leave mediated synthesized SiO2 nanoparticles: Study of adsorption mechanism, isotherms and enhanced adsorption capacity for removal of Cr (VI) from aqueous solution

Green synthesis of nanoparticles (NPs) provides economic and environmental benefits as an alternative to chemical or physical methods. Furthermore, the surface properties of such NPs can be modulated by means of the functionalization with different groups making them suitable for various advanced functional applications including water pollutants removal using adsorption technique. In the present work, an eco-friendly synthesis route for nano-adsorbent SiO2 NPs and subsequent surface modifications for enhanced adsorption capacity in removal of Cr(VI) ions from aqueous solution are reported. The green synthesis of SiO2 NPs was carried out using simple bamboo leaves followed by surface modification with amine (A-SiO2) and carboxylic (C–SiO2) functional groups with aim to study the effect of functionalization on adsorption capacity. These nano-adsorbents were characterized by FTIR, SEM, XPS, BET, and zeta potential. and adsorption of Cr(VI) was studied at varying parameters i.e. NPs mass, contact time, and solution pH. The investigation shows interesting results revealing the importance of interactions between the surface functional groups on SiO2 NPs and Cr(VI) species as well as experimental conditions for the choice of surface modifier to achieve a maximum adsorption capacity. The adsorption mechanism has been studied using Langmuir, Freundlich and Temkin adsorption isotherms. The maximum adsorption capacity has been achieved in the case of A-SiO2 NPs which was found to 174 mg/g and much higher than that of SiO2 and C–SiO2 NPs attributed to the selective adsorption and pH conditions. Additionally, A-SiO2 NPs exhibit excellent recyclability indicating their suitability for promising and long term potential applications. This study provides a novel, simple and cost-effective synthesis/surface engineering technology for producing high performance recyclable nano-adsorbents for adsorptive removal of Cr(VI).

Optimization of the Conditions for the Synthesis of Zinc Oxide Nanoparticles by Plasma Chemical Method

Zinc oxide nanoparticles (ZnO) have a lot of useful properties, thanks to which they are used in various fields of science, technology and medicine. The properties of such nanoparticles largely depend on the method of their synthesis. This paper presents the results of optimization the conditions for the synthesis of zinc oxide nanoparticles by the plasma chemical method, as well as, clarifying the structure of the obtained samples. It is shown that the lack of air and the duration of the discharge affect the size and structure of the resulting particles. Analysis of the data obtained shows that synthesis in a vacuum chamber on graphite electrodes located inside a galvanived pipe at a pressure of 66, 7 k PA, a voltage of 20 V, DC power of 75 A is optimal for obtaining zinc oxide nanorods by the plasma chemical method.

Probing the cavitation bubbles produced during laser ablation of copper immersed in liquid under tightly focused conditions using shadowgraphy technique

Pulsed laser ablation in liquid (PLAL) has emerged as an efficient method for production of nanoparticles (NPs), especially noble metal NPs. The main advantage of synthesizing NPs by this method is that bare as well as functionalized NPs can be synthesized with great ease. Noble metal NPs have proven to be extremely useful in the fields of biomedicine, sensing technology, energy storage, etc. The properties of such NPs strongly depend on the transient dynamics that occur on the target surface. Hence, in order to control the properties of the NPs and increase their productivity, it is crucial to study the dynamics associated with the technique. Keeping this in mind, a study has been conducted to understand the effect of tight focusing of the pulsed laser beam on the cavitation bubbles generated during PLAL performed on copper (Cu) target using shadowgraphy technique. The results reveal novel dynamics of the formation of cavitation bubbles due to the breakdown of the liquid in addition to the bubble attached to the target. The analysis of such bubbles is carried out and its evolution is studied.

Sulfide Ligands in Hybrid Semiconductor-Metal Nanocrystal Photocatalysts: Improved Hole Extraction and Altered Catalysis.

Hybrid semiconductor-metal nanocrystals manifest efficient photocatalytic activity related to the metal domain promoting charge carrier separation and providing an active catalytic site. The surface properties of such nanoparticles are also of paramount importance in determining their photocatalytic activity. Addressing the combination of surface effects in catalysis on metals, with the electronic properties of hybrid nanoparticles, we examined the effect of coating CdS-Au hybrid nanoparticles with sulfide, an anion that is expected to bind strongly to both domains, on the photocatalytic functionality. Upon sulfide coating, one-electron processes - namely the oxidative production of hydroxyl radicals and the reductive production of superoxide - were increased, whereas the activity for two-electron reduction processes - H2 and hydrogen peroxide generation - was hampered. These findings indicate a double-edged sword effect for sulfide coating that on one side relieves the hole extraction bottleneck from the semiconductor segment and, on the other hand, poisons the metal domain restricting its reductive capacity for the two-electron processes requiring a chemisorption step on the metal surface. The work further demonstrates the importance of surface properties for the photocatalytic action of such hybrid nanoparticle systems.

The effects of anisotropy on solvent-suspended ‘superparamagnetic’ nanoparticles: Magnetization step on melting

The magnetic anisotropy of single-domain magnetic nanoparticles can influence their behaviour significantly even at temperatures above the blocking temperature as conventionally defined. We compare the magnetic properties of such nanoparticles that are free to rotate, and the same nanoparticles with random but fixed orientations. When free to rotate, the particles show Langevin behaviour as expected, but when the orientations are fixed, their magnetic anisotropy causes deviations from this behaviour. These deviations may be observed directly in the M-H curves. They also cause a step in the M-T curve measured for a zero-field cooled sample of nanoparticles suspended in a solvent at the solvent’s melting point. The step occurs because magnetic anisotropy causes M for particles with random but fixed orientation to be lower than for the same particles that are free to rotate when the solvent melts. The size of the step reaches a maximum at a finite applied field. This phenomenon is important because it can be used to determine the fraction of magnetic nanoparticles that are immobilized, for example by adsorption to ice in a freeze-concentrated solution.

Direct Synthesis of NaBH4 Nanoparticles from NaOCH3 for Hydrogen Storage

Hydrogen is regarded as a promising energy carrier to substitute fossil fuels. However, storing hydrogen with high density remains a challenge. NaBH4 is a potential hydrogen storage material due to its high gravimetric hydrogen density (10.8 mass%), but the hydrogen kinetic and thermodynamic properties of NaBH4 are poor against the application needs. Nanosizing is an effective strategy to improve the hydrogen properties of NaBH4. In this context, we report on the direct synthesis of NaBH4 nanoparticles (~6–260 nm) from the NaOCH3 precursor. The hydrogen desorption properties of such nanoparticles are reported as well as experimental conditions that lead to the synthesis of (Na2B12H12) free NaBH4 nanoparticles.

SYNTHESIS AND CRYSTALLOCHEMICAL PROPERTIES OF Ce-SUBSTITUTED NANOPARTICLES OF MANGANITE (La,Sr)MnO3

Serious of Ce-substituted lanthanum-strontium man-ganites La0.7–xSr0.3CexMnO3 (x = 0–0.2) nanoparticles were synthesized by sol-gel method with further heat treatment of precursors at 800 °C. Crystallographic properties of obtained nanoparticles were investiga-ted by X-ray diffraction method. According to XRD data, it was established that the substitution of lan-thanum ions by cerium in the crystalline structure and formation of single-phased nanoparticles occurs only up to 5 % mol. of Ce regardless of the heating temperature. Linear decreasing the cell volume of nanoparticles in this concentration range of Ce satis-fies the Vegard law and indicates on the formation of a continuous series of solid solutions with the dis-torted perovskite up to 5 % of Ce. At higher concen-trations of Ce there are additional peaks on the XRD patterns, which point on the formation of an addi-tional phase of CeO2. According to TEM studies, it was calculated that the average size of was 30–40 nm. To estimate heating efficiency of synthesized nanoparticles in the alternating magnetic field, mag-netic fluids based on the synthesized nanoparticles and aqueous dextran solution were prepared. It was shown that they effectively heated up to controlled temperatures in an alternating magnetic field, and their heating efficiency was directly proportional to the increase of the concentration of cerium. Accor-ding to the results of the complex studies, it was shown the possibility to synthesize single-phase Ce-substituted nanoparticles of manganite with a pe-rovskite structure. It was established that cerium does not significantly influence on the change of magnetic properties of such nanoparticles and they are promising for further investigations as the in-ducers of magnetic hyperthermia, as well as for the biological tests.

Phase Separation in Liquid Metal Nanoparticles

Nanoparticles produced from gallium-based liquid metal alloys have been explored for developing applications in the fields of electronics, catalysis, and biomedicine. Nonetheless, physical properties, such as phase behavior at micro-/nanosize scale, are still significantly underexplored for such nanoparticles. Here, we conduct an in situ investigation of phase behavior for gallium-based liquid metal nanoparticles and discover the unprecedented coexistence of solid particles in spherical liquid metal shells without the support of a crystalline substrate. The particles can also transform into solid Janus nanoparticles after temperature cycling. In addition, we investigate the optical properties of the nanoparticles before and after phase separation using in situ electron energy-loss spectroscopy. Most importantly, we discover that increasing the content of indium within the nanoparticle can stabilize the solid-core/liquid-shell structure at room temperature. This study provides a foundation to engineer liquid metal nanoparticles for developing new applications in nanoscale optical platforms and shape-configurable transformers.Although various electronic, chemical, and biomedical applications have been demonstrated for nanoparticles made from gallium-based liquid metal alloys, fundamental physical properties such as phase behavior of such nanoparticles are still significantly underexplored. Here, Tang and coworkers present the in situ investigation of phase separation in binary and ternary spherical liquid metal nanoparticles upon cooling, and demonstrate the coexistence of solid core/liquid shell without the support of a crystalline substrate. This study provides insight into engineering such nanoparticles for the development of new applications.Despite gallium-based liquid metal alloys attracting extensive attention for various applications, their phase behavior at the nanoscale is still underexplored. Understanding the impact of phase separation in nanoparticles can be extremely useful for developing new structures and exploring suitable applications. Here, we report on the investigation of phase behavior for spherical nanoparticles made from gallium-based liquid metal alloys upon cooling. We discover the thermally stable coexistence of solid cores in spherical liquid metal shells without the support of a crystalline substrate at room temperature. Given the unique properties of liquid metal, together with the facile process for producing core-shell and Janus nanoparticles, this work will encourage further investigation of the properties of such nanoparticles for developing applications in the fields of electronics, catalysis, nanomedicine, and beyond.

Synthesis, Crystal Structure, and Liquid Exfoliation of Layered Lanthanide Sulfides KLn2CuS6 (Ln = La, Ce, Pr, Nd, Sm).

Among the great amount of known lanthanide nanoparticles, reports devoted to chalcogenide ones are deficient. The properties of such nanoparticles remain almost unknown due to the lack of simple and proper synthetic methods avoiding hydrolysis and allowing preparation of oxygen-free lanthanide nanoparticles. A liquid exfoliation method was used to select the optimum strategy for the preparation of quaternary lanthanide sulfide nanoparticles. Bulk KLn2CuS6 (Ln = La-Sm) materials were obtained via a reactive flux method. The crystal structures of three new members of the KLn2CuS6 series were determined for Pr, Nd, and Sm as well as for known KLa2CuS6. KLn2CuS6 (Ln = La, Pr, Nd) compounds crystallize in the monoclinic C2 /c space group, whereas KSm2CuS6 crystallizes in the orthorhombic Fddd space group. The analysis of their electronic structures confirms that the main bonding interactions occur within the anionic {Ln2CuS6}- layers. Due to their layered structure, exfoliation of these compounds is possible using ultrasonic treatment in appropriate solvents with the formation of colloidal solutions. Colloidal particles show a plate-like morphology with a lateral size of 100-200 nm and a thickness of 2-10 nm. Highly negative or positive charges found in isopropanol and acetonitrile dispersions, respectively, are associated with high stability and concentration of the dispersions.

Presence of Fluorescent Carbon Nanoparticles in Baked Lamb: Their Properties and Potential Application for Sensors.

The presence of nanoparticles in food has drawn much attention in recent years. Fluorescent carbon nanoparticles are a new class of nanostructures; however, the distribution and physicochemical properties of such nanoparticles in food remain unclear. Herein, the presence of fluorescent carbon nanoparticles in baked lamb was confirmed, and their physicochemical properties were investigated. The fluorescent carbon nanoparticles from baked lamb emit strong blue fluorescence under ultraviolet light with a 10% fluorescent quantum yield. The nanoparticles are roughly spherical in appearance with a diameter of around 2.0 nm. Hydroxyl, amino, and carboxyl groups exist on the surface of nanoparticles. In addition, the nanoparticles could serve as a fluorescence sensor for glucose detection through an oxidation-reduction reaction. This work is the first report on fluorescent carbon nanoparticles present in baked lamb, which provides valuable insight into the physicochemical properties of such nanoparticles and their potential application in sensors.

High Excitation Intensity Opens a New Trapping Channel in Organic–Inorganic Hybrid Perovskite Nanoparticles

We investigated the excited-state dynamics of CH3NH3PbBr3 perovskite nanoparticles (NPs) and bulk crystals under various excitation intensity regimes using transient absorption spectroscopy. We confirmed the sub-band gap hole trap states with optical transition to the conduction band in both samples. In bulk crystals, the excited-state dynamics is independent of pump intensity. However, in NPs, pronounced intensity dependence appears. At low intensities, the hole trap states do not affect the excited-state dynamics due to the potential barrier between the photogenerated holes and the surface trap states. When the excitation density is much higher than one per NP, charge accumulation makes hot holes overcome the barrier and get trapped with electrons long living in the conduction band (≫10 ns). This explains the high emissive properties of such NPs despite the existence of surface traps. However, in the application of emitting devices requiring high excitation intensity, the surface trapping becomes signif...

Synthesis of silica nanoparticles for encapsulation of oncology drugs with low water solubility: effect of processing parameters on structural evolution

Silica nanoparticles with tailored properties have been developed for a variety of biomedical applications, with particular emphasis on their use as carriers for the encapsulation and controlled release of bioactive species. Among the various strategies described, silica nanoparticles with uniform mesoporosity (MSN) prepared in aqueous solution at elevated temperatures using cetyltrimethylammonium bromide as a template have a range of desirable properties. However, the processing windows available to control the dimensions and other key properties of such nanoparticles prepared using fluoride salts as catalysts have not been elucidated, with mixed products containing gel fragments and non-uniform products obtained under many conditions. Here, we present a parametric study of the synthesis of MSN under fluoride-catalysed conditions using tetraethylorthosilicate as silica precursor. The processing conditions required to produce uniform nanoparticles with controlled dimensions are elucidated, together with the conditions under which dried powders can be re-dispersed in aqueous solution after long-term storage to regenerate unaggregated nanospheres with dimensions (as measured by dynamic light scattering) comparable to those measured via scanning electron microscopy analysis of the dried material. The ability to dry and store such powders for extended periods of time is an important requirement for the use of such materials in drug delivery applications. Preliminary results demonstrating the use of such MSNs as hosts for oncology drugs [substituted 3-hydroxyquinolinones (3-HQ)] with low water solubility (≪1 µg/g H2O) are presented, with loadings of several wt% demonstrated. The ability of the silica host to protect the 3-HQ from oxidative degradation during impregnation and release is discussed.

Enhanced magnetic properties in antiferromagnetic-core/ferrimagnetic-shell nanoparticles.

Bi-magnetic core/shell nanoparticles are gaining increasing interest due to their foreseen applications. Inverse antiferromagnetic(AFM)/ferrimagnetic(FiM) core/shell nanoparticles are particularly appealing since they may overcome some of the limitations of conventional FiM/AFM systems. However, virtually no simulations exist on this type of morphology. Here we present systematic Metropolis Monte Carlo simulations of the exchange bias properties of such nanoparticles. The coercivity, HC, and loop shift, Hex, present a non-monotonic dependence with the core diameter and the shell thickness, in excellent agreement with the available experimental data. Additionally, we demonstrate novel unconventional behavior in FiM/AFM particles. Namely, while HC and Hex decrease upon increasing FiM thickness for small AFM cores (as expected), they show the opposite trend for large cores. This presents a counterintuitive FiM size dependence for large AFM cores that is attributed to the competition between core and shell contributions, which expands over a wider range of core diameters leading to non-vanishing Hex even for very large cores. Moreover, the results also hint different possible ways to enhance the experimental performance of inverse core/shell nanoparticles for diverse applications.

Effect Of Nanomaterials Sizes On The Dispersion Stability Of Biodiesel Based Nanofluids

The effect average alumina nanoparticle sizes on the long term dispersion stability of biodiesel based nanofluids was investigated. Alumina nanoparticles having two different average sizes (~13nm and ~28nm) were dispersed in the Jatropha biodiesel as the base fluids. The effect of alumina (Al2O3) nanoparticles sizes on the stability of nanofluids was investigated to achieve more stable nanoparticles dispersed nanofluids having longer duration for potential use in alternative fuel energy applications. Different volume fractions (VF) such as 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% nanofluids were prepared by using two different sizes of alumina nanoparticles (~13nm and ~28nm) by using the surfactants Span 80 and Tween 80 in the ratio of 1:1. The results revealed that the nanofluids having the smaller average sizes alumina nanoparticles and 0.1% volume fraction were stable for more than one year as compared to the larger (two times) size nanoparticles having same 0.1% volume fraction. Such long term stable biodiesel based nanofluids can be used as the alternative fuel energy for future automobiles and transportation sectors due to the fuel properties of such nanoparticles dispersed nanofluids retaining the commercial diesel properties.

149 DEVELOPMENT OF AN IN VITRO BIOLUMINESCENT SPERM BINDING ASSAY: PRELIMINARY DATA

Quantum dot technology has enabled researchers to incorporate the intrinsic properties of such nanoparticles into physiological exploration. Previous work from our laboratory has demonstrated that quantum dots can be incorporated into spermatozoa without deleterious effects to physiological parameters such as motility, viability, and fertilizing potential (Feugang et al. 2012). However, the journey of spermatozoa within the female reproductive tract is met with many physicochemical obstacles and checkpoints that include the binding of spermatozoa to utero-oviducal epithelial cells. Moreover, the binding ability/affinity of quantum dot-labelled spermatozoa has not been tested and therefore, the objective of this study is to test the binding semblance of quantum dot-labelled spermatozoa to uterine epithelial cells compared to normal sperm, and the subsequent use of the technology to develop a bioluminescent sperm binding assay. Porcine uterine epithelial (PUE) cells were seeded into 96-well clear-bottomed plates (20 000 cells/well) and allowed to grow to 95% confluency. Motile spermatozoa were selected from fresh pooled semen of fertile boars and labelled with quantum dot nanoparticles to form quantum sperm, as previously described (Feugang et al. 2012). Final concentrations of 107 labelled (QD+) and non-labelled (QD–) spermatozoa were added to monolayers of PUE cells and co-incubated in PBS/polyvinylpyrrolidone (PVP) at 37°C, 5% CO2. The control consisted of PUE cells alone in the PBS/PVP medium. Each treatment was performed in triplicate and experiments were repeated 3 times. After 1 h of co-incubation, the supernatant from each well was transferred to the adjacent three wells. The co-incubated wells containing expected PUE-sperm binding were then washed 3 times with PBS/PVP to eliminate any unbound sperm. PUE-quantum sperm (QD+) and PUE-non-labelled sperm (QD–) complexes were verified using bright field microscopy, followed by measurement of photonic emission from each well (GloMax Multi Detection System, Promega, Madison, WI, USA). Data was analysed by ANOVA with the threshold of significance fixed at P < 0.05. There were no visual differences in binding patterns between QD+ and QD–, which appeared similar under the microscope. However, the photonic signals (relative luminescent units; RLU) from QD+ wells were significantly higher than both the control and QD– wells (2534.84 ± 639.91 v. 542.46 ± 639.91 and 806.48 ± 639.91 RLU; P < 0.05). Supernatants collected from the QD+ wells, representing unbound quantum sperm, had the highest photonic emissions when compared to all other wells, with or without spermatozoa (19 948.23 ± 639.91 RLU; P < 0.05). Results demonstrate that quantum dot nanoparticles can be incorporated into boar spermatozoa without affecting their binding affinity to uterine epithelial cells, and their subsequent use in a biophotonic sperm binding assay. Further optimization and experimentations are ongoing to establish whether bioluminescent quantum sperm could serve to develop sensitive in vitro binding assays to better characterise sperm viability. Support was provided by U.S. Department of Agriculture Agricultural Research Service (USDA-ARS) grant number 58-6402-3-0120

Radial Structure of Free Yb/YbO Nanoparticles Created by Oxidation Before or After Aggregation with Divalent Instead of Trivalent Oxide

Nanoparticles consisting of Yb and its divalent oxide YbO have been created by two different oxidation approaches based on the gas-aggregation method with magnetron sputtering. In one type of nanoparticles, the Yb oxide molecules, created by reactive sputtering before the aggregation, agglomerate predominantly in the interior of mixed-composition nanoparticles. In the other type, the oxide is formed by exposing the preformed metallic Yb nanoparticles to oxygen, which at certain conditions is believed to oxidize primarily the surface of such nanoparticles. Such segregated stoichiometry has been disclosed using Yb 4f core-level photoelectron spectroscopy at a series of oxidation conditions for each type of production. In contrast to a typical macroscopic case where Yb is trivalent, in both production cases, Yb is divalent in the oxide. By using the production methods suggested, it becomes possible to tailor the electronic and thus the physical and chemical properties of such nanoparticles, which are discussed in the literature as building blocks for photonic, electronic, and magnetic nanoscale devices.

Effect of mixing tool on magnetic properties of hematite nanoparticles prepared by sol–gel method

X-ray diffraction, Mössbauer and magnetization measurements have been performed on hematite nanoparticles, prepared by sol–gel method, to study the effect of the mixing tools used in the preparation on their magnetic properties. It has been shown that the mixing tool, i.e. magnetic or mechanical, has a crucial effect on the magnetic behaviors of magnetic nanoparticles. Furthermore, the degree of purity of nitrogen gas used in the preparation process also plays a minor role in magnetic properties of such nanoparticles.

Phase Behavior of DNA-Based Dispersions containing Carbon Nanotubes: Effects of Added Polymers and Ionic Strength on Excluded Volume

Ordered phases containing single-walled carbon nanotubes (SWNTs) are essential to exploit the highly anisotropic properties of such nanoparticles. Knowledge of the phase behavior for the above dispersions is therefore needed. Unfortunately, the processing of nanotubes at high concentration remains experimentally challenging. To date, solvent evaporation and ultracentrifugation procedures have been used to increase the volume fraction of carbon nanotubes and obtain (pseudo)-binary phase diagrams. We present here a novel phase separation strategy, allowing investigations of the phase behavior of concentrated dispersions of DNA-stabilized carbon nanotubes. This strategy is based on the osmotic compression due to added polymers such as sodium dextransulfate (SDxS) or polyethylene glycol (PEG) and on the control of the ionic strength. The phase behavior of the compressed DNA/SWNTs complexes is analyzed and discussed. It is observed that added polymers induce the separation of a SWNT-rich anisotropic phase in e...