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  • First-principles study of AuS n (2 ≤ n ≤ 7) clusters: structural, electronic, magnetic, spectral properties, and adsorption properties with O 2 and H 2 O
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-23
    Gui-Jun Chen, Shao-Yi Wu, Qing Zhang, Hao Fu, Qin-Sheng Zhu, Xiao-Yu Li, Xiao-Hong Chen

    Abstract Based on the density functional theory (DFT) method, the geometrical structures, relative stability, electronic, and spectral properties of AuSn (2 ≤ n ≤ 7) clusters are systematically studied, whose sizes are largely in the range of 0.3–0.5 nm. AuS4 and AuS3 show the highest and lowest energy gaps and hence the highest chemical stability and chemical activity, respectively. The total magnetic moment is 3.0 and 1 (or 0) μB for AuS4 and other clusters, respectively, which largely (about 99.9%) arise from the local magnetic moment of S atoms. The average polarization tensor for single atom (<\( \overline{\alpha} \)>) generally increases with increasing the number of S atoms, with the maximum 91.72 a.u. for AuS7, corresponding to the most significant delocalization effect. AuS4 cluster exhibits the highest polarizability anisotropic invariant Δα (≈ 350.56 a.u.) and the lowest total dipole moment (≈ 0.06 D) among all systems, corresponding to the strongest anisotropic response to external electric field and the weakest polarization, respectively. The IR, Raman, UV-Vis, and PES spectra are simulated for AuSn (2 ≤ n ≤ 7) clusters with the structures of the lowest isomers. The O–O and O–H bond lengths, adsorption energies, vibration frequencies, and density of states are also calculated for AuS4 and AuS3 adsorbing one O2 and H2O molecules, respectively. The adsorption capacity of AuS3 for both gas molecules is higher than AuS4, and AuSn (n = 3, 4) clusters are more favor to adsorb O2 than H2O.

    更新日期:2020-01-23
  • A three-dimensional heterogeneous ZnCo-PBA@α-Co(OH) 2 nanostructure for high-performance supercapacitors
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-21
    Xueying Sun, Siqi Li, Rongmei Liu, Xiulun Sun, Xinjie Liu, Anran Li, Wen Li

    Abstract In this work, we designed a simple hydrothermal synthetic method for a ZnCo-PBA@α-Co(OH)2 nanosphere@nanosheet material with good electrochemical properties. The obtained material had a specific capacitance of 423.92 F g−1 at 1 A g−1 and a cycling retention ratio of 78.48% after 1000 cycles at 5 A g−1. A hybrid supercapacitor device (ZnCo-PBA@α-Co(OH)2//AC) assembled with activated carbon as the negative electrode had a specific capacitance of 122.4 F g−1 at 1 A g−1, a cycling retention rate of 73.53% after 5000 cycles at 5 A g−1, and a very high energy density of 49.13 Wh kg−1 at power density of 1734.0 W kg−1. The significantly improved electrochemical performance of the ZnCo-PBA@α-Co(OH)2 nanocomposites can be attributed to the positive synergistic effects of the porous structure of the PBA material and the large specific surface area of the α-Co(OH)2 nanosheets, on the ion permeability and number of active sites in the reinforcing material; thus, this composite is a potential material for use in future energy storage systems.

    更新日期:2020-01-22
  • Exploring the antibacterial potential and unraveling the mechanism of action of non-doped and heteroatom-doped carbon nanodots
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-20
    Theodoros G. Chatzimitakos, Athanasia I. Kasouni, Anastassios N. Troganis, Constantine D. Stalikas

    Abstract A comprehensive study of the antibacterial (bacteriostatic and bactericidal) properties of non-doped carbon nanodots (CNDs), nitrogen-doped (N-doped), and nitrogen/sulfur co-doped (N,S-doped) CNDs against Escherichia coli (a model organism) is discussed herein. The CNDs, with a size of ca. 5 nm, were found to be capable of inhibiting the growth of the bacterial biofilm but not significantly the growth of planktonic bacteria. Heteroatom doping was found to considerably improve the potential of CNDs as bactericidal agents. Further experiments were conducted to shed light on the potential mechanism of the antibacterial activity of the CNDs. The results showed that the CNDs do not interact with the cellular membrane via electrostatic forces. Following a simple metabolomic workflow, no alterations of the bacterial metabolome were observed except for the activation of the metabolism of α-linolenic acid. The CNDs neither oxidize cell membrane lipids and intracellular proteins nor elevate the concentration of reactive oxygen species in cells. Finally, the interactions of CNDs with genomic DNA and RNA revealed that CNDs are able to intercalate into their structure. The different affinities of the three kinds of CNDs for DNA/RNA account for the differences in their antibacterial activity and constitute the main mechanism via which CND activity is achieved. Graphical abstract

    更新日期:2020-01-21
  • Structure and electronic properties of Au n Pt ( n = 1–8) nanoalloy clusters: the density functional theory study
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-17
    Prabhat Ranjan, Tanmoy Chakraborty

    The study of bimetallic nanoalloy clusters is of considerable interest due to its interesting electronic, optical, magnetic and catalytic properties. The geometrical structure and electronic properties of AunPt (n = 1–8) nanoalloy clusters are studied by using the density functional theory methodology. The result exhibits that the ground-state configurations of AunPt clusters favour planar confirmation in this molecular range. The most stable cluster is Au3Pt, which is having rhombus structure with symmetry group C2v and can be considered as building blocks for developing large clusters. The computed HOMO-LUMO energy gap of Au3Pt nanoalloy cluster is 1.741 eV. The energy gap in this particular range supports the use of bimetallic clusters as nonlinear optical devices and optoelectronic materials. The DFT-based global descriptors viz. HOMO-LUMO energy gap, electronegativity, hardness, softness and electrophilicity index are also studied. The computed HOMO-LUMO energy gap and chemical hardness exhibit a pronounced odd-even oscillation behaviour as a function of cluster size, n.

    更新日期:2020-01-17
  • Evaluation of acute toxicity and copper accumulation in organs of Wistar rats, 14 days after oral exposure to copper oxide (II) nano- and microparticles
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-24
    Magno Maciel-Magalhães, Renata J. Medeiros, Jussara S. Bravin, Beatriz F. C. Patricio, Helvécio V. A. Rocha, Elan C. Paes-de-Almeida, Lisia M. G. Santos, Silvana C. Jacob, Tiago C. M. Savignon, Fábio C. Amendoeira

    Copper oxide (II) nanoparticles (CuO-NPs) have been increasingly used in products of human interest, such as coating for food packaging and wood protection. The main objective of this study was to evaluate in vivo acute toxicity of CuO-NPs after oral exposure and compare it with CuO microparticles (CuO-MPs). Female rats were orally exposed, through gavage procedure, to the analyzed materials. After 14 days of observation, hematological, biochemical, histopathological, and copper organ accumulation analyses were performed. CuO-NPs (25.17 ± 8 nm) and CuO-MPs (1.092 ± 0.52 μm) were characterized and compared regarding their acute oral toxicity. Animals treated with CuO-NPs at the dose of 2000 mg kg−1 presented changes in feces and copper hepatic accumulation. Histopathological exam of livers demonstrated hepatocyte binucleation and megalocytosis. None of the animals tested with CuO-MPs showed any alterations. Oral exposure to CuO-NPs, at the dosage of 2000 mg kg−1, may cause mild transitory liver damage, mainly resolved during a 14-day post-exposure period. Also, the nanoparticulated material showed to be more toxic than the microparticulated one.

    更新日期:2020-01-17
  • Particle size analysis and characterization of nanodiamond dispersions in water and dimethylformamide by various scattering and diffraction methods
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-16
    Tomáš Kovářík, Petr Bělský, David Rieger, Jan Ilavsky, Věra Jandová, Michael Maas, Pavol Šutta, Michal Pola, Rostislav Medlín

    Over the past few decades, detonation nanodiamonds (NDs) have gained increased attention due to their unique physicochemical properties. Various methods for preparation of ND suspensions have been introduced. This paper presents thermally annealed nanodiamonds dispersed via sonication and separated by centrifugation in deionized water and dimethylformamide in five weight concentrations ranging from 0.05 to 1 wt%. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied to study the thermal behavior of NDs. Crystallographic properties of air-annealed and dispersed NDs were examined by means of X-ray diffraction (XRD). Nanodiamond dispersions were analyzed by static light scattering (SLS), dynamic light scattering (DLS), ultra-small- and small-angle X-ray scattering (USAXS/SAXS), and high-resolution transmission electron microscopy (HRTEM). SLS and DLS give similar results of ND− aggregates mean size between ~ 61 and 73 nm, regardless of solvent type and nanoparticle concentration. For dispersions with increasing concentrations of NDs, neither increased aggregate size nor different kinetics of separation during sonication and centrifugation were observed. USAXS/SAXS provided the aggregates size (2Rg) in the range from 57 to 65 nm and size of primary particles from 5.4 to 5.8 nm. HRTEM also showed presence of larger aggregates with tens of nanometers in size in both water and DMF dispersions, and size of primary particles ranging from 5.5 to 6 nm in very good agreement with SAXS.

    更新日期:2020-01-16
  • Comment on: “Bidimensional bound states for charged polar nanoparticles”
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-03
    Paolo Amore, Francisco M. Fernández

    In a recent paper, Castellanos-Jaramillo and Castellanos-Moreno proposed a simple quantum-mechanical model for an electron in the vicinity of an ionized nanostructure with a permanent electric dipole. They chose the interaction of the electron with the charge and the dipole in such a way that the resulting Schrödinger equation is separable into radial and angular parts. In this comment, we show that those authors did not solve the angular eigenvalue equation with proper periodic boundary conditions and that they also made a mistake in the elimination of the first derivative in the radial equation. Such errors invalidate their results of the Einstein coefficients for the \(\left (GaAs\right )_{3}\) system considered.

    更新日期:2020-01-16
  • DFT study of adsorption of glyphosate pesticide on Pt-Cu decorated pyridine-like nitrogen-doped graphene
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-04
    Mandeep, Archa Gulati, Rita Kakkar

    Density functional theory (DFT) studies have been performed on the unprecedented adsorption of glyphosate pesticide on modified pyridine-like nitrogen-doped graphene (PNG) for the purpose of water remediation. The interaction of glyphosate on the PNG sheet, as well as on Pt-Cu decorated PNG substrates, is investigated. The Pt4-nCun (n = 0–4) clusters, such as Pt4, Pt3Cu1, Pt2Cu2, Pt1Cu3, and Cu4, have been decorated on the PNG surface to increase the reactivity of the adsorbent toward glyphosate. The adsorption of glyphosate on the PNG surface is physisorption, indicated by the low adsorption energy and negligible charge transfer. The mixed metal (Pt-Cu) clusters play a significant role in enhancing the interactions between the adsorbate and adsorbent, leading to better results for the adsorption of glyphosate. Exothermic chemisorption is shown by all Pt4-nCun clusters decorated PNG substrates, and chemical bond formation takes place between the adsorbate and adsorbent. Various electronic properties, like electron density difference plots, give information about the adsorption behavior of glyphosate, and density of states (DOS) plots reveal that on decorating with the cluster, the substrates start exhibiting magnetic character.

    更新日期:2020-01-15
  • Determination of particle size distributions and transformation enthalpies from the temperature course of a phase transformation
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-14
    Dieter Vollath

    The presented analysis of the temperature course of a phase transformation of nanoparticles offers a powerful tool to obtain data for the particle size distribution and the enthalpy of transformation. The analysis starts with the temperature distribution within an ensemble of nanoparticles and a functional relation between particle size and transformation temperature. In contrast to the Maxwell-Boltzmann distribution, in case of nanoparticles, the distribution of the temperature of the particles follows a normal distribution. Finally a reliable characterization of the specimen and the transformation in question are presented. These results, particularly the particle size distribution, represent – in many cases – a statistically more significant result as compared to the outcome, obtained by evaluation of electron micrographs. Looking at the problems of microcalorimetric determination of reaction enthalpies, one may realize comparable problems. By comparison of the experimental data with the calculated ones, one may obtain additional information about the interaction of the particles within the ensemble.

    更新日期:2020-01-15
  • Spindle Mn 2 O 3 /carbon hybrid with homogeneous structure as advanced electrodes for supercapacitors
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-13
    Yunlei Fu, Fusheng Liu, Hui Wang

    Despite the great advantages of manganese oxide/carbon composites as the electrodes for supercapacitors, homogeneous hybrid with intimate contact between manganese oxide and carbon has been rarely achieved. Here, spindle Mn2O3/carbon hybrid was designed and synthesized via a hydrothermal process following a heat treatment procedure, in which Mn2O3 was homogeneously and intimately contacted with carbon. When the Mn2O3/carbon hybrid was evaluated as the active material in an asymmetric supercapacitor, a specific capacitance of 235 F g−1 was obtained at a current density of 50 mA g−1, and a rate capability was 44.9% specific capacitance retention even when the current density is increased by 100 times, as well as a long-term cycle was stabilize.

    更新日期:2020-01-14
  • Catalysis of sugarcane-bagasse pyrolysis by Co, Ni, and Cu single and mixed oxide nanocomposites
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-13
    Mahmoud Mohamed Emara, Shrouq Hossam Ali, Taher Salah Edin Kassem, P. Gregory Van Patten

    Abstract Pyrolysis of biomass is an important process in which renewable biological waste is converted to energy products and preliminary chemicals. Therefore, various types of catalysts, including metal oxides, have been investigated for more efficient and selective biomass pyrolysis. Co, Ni, and Cu single and mixed metal oxide (SMO and MMO) nanoparticles (NPs) of 3 to 47 nm were synthesized, characterized, and studies for their catalytic activities towards pyrolysis of sugarcane bagasse (PSCB). After mixing the oxide NPs with bagasse, thermogravimetry was performed at a heating rate of 5 °C/min from ambient temperature to 600 °C. Thermogravimetric analysis followed by kinetic calculations of the activation energy through Coats−Redfern model show that all oxide NPs of this study exhibit catalytic activity towards cellulose and hemicellulose thermal degradation during PSCB, in the order MMO > SMO. Cu-containing SMO and MMO NPs show exceptional catalytic activities compared to their analogues. On the other hand, lignin degradation kept proceeding over a wide range of high temperature, just like that of the plain PSCB. This is considered selective enhancement of the catalysis of cellulose and hemicellulose thermal degradation versus lignin degradation, which is promising for improving the composition and quality of PSCB products. Only Cu-containing double and triple MMOs were so catalytically active that they catalyzed lignin degradation along with the cellulose and hemicellulose.

    更新日期:2020-01-14
  • Synthesis and structural characterization of iron-cementite nanoparticles encapsulated in carbon matrix
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-13
    Leon Avakyan, Aram Manukyan, Alena Bogdan, Harutyun Gyulasaryan, José Coutinho, Ekaterina Paramonova, Galina Sukharina, Vasiliy Srabionyan, Eduard Sharoyan, Lusegen Bugaev

    Carbon-encapsulated iron-cementite (Fe-Fe3C) nanoparticles, promising nanomaterials for medicine due to their valuable magnetic properties, were synthesized by a single-step solid-state pyrolysis of iron phthalocyanine. To obtain required magnetic characteristics of such nanoparticles by governing of the pyrolysis conditions one needs reliable structural information of the atomic architecture of the obtained nanoparticles of composition (Fe-Fe3C), in which Fe atoms have different types of the local surrounding. The latter complicates the structural characterization of samples, which was performed using the complementary methods of TEM, SAXS, XRD, XANES, and EXAFS and the results of simulations by the method of reactive force field molecular dynamics (ReaxFF MD). The size of the particles is on the order of 10 nm with cementite concentration of about 60–70 wt%. The simulations enabled to reveal that the most plausible combinations of the local structures of Fe atoms in (Fe-Fe3C) nanoparticle result in the difference of corresponding atomic pair radial distribution functions relatively to iron (RDF), which can be further filtered through the comparison with experimentally obtained RDF for iron atoms in the studied sample. Such RDF was derived from experimental Fe K-edge EXAFS in the sample by Fourier transform multi-shell processing within harmonic approximation and using the results of the analysis of SAXS, XRD, and XANES. The used approach, based on the filtering of ReaxFF MD-calculated RDFs via comparison with the EXAFS derived RDF, revealed that for particles of composition (Fe-Fe3C) with XRD derived iron:cementite ratio of \(\sim 40\):60 wt% and sizes bigger than 4 nm, the architecture with iron in core region of particle and cementite in its shell (Fe@Fe3C) is the most probable for the mean nanoparticle comparing with architectures of the inverted core-shell (Fe3C@Fe) or the mixture of iron and cementite phases (Fe+Fe3C).

    更新日期:2020-01-14
  • Effect of downsizing the maricite α-phase sodium cobalt phosphate (α-NaCoPO 4 ) in sodium-ion battery
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-10
    G. Savithiri, V. Priyanka, R. Subadevi, M. Sivakumar

    Maricite α-phase sodium cobalt phosphate (α-NaCoPO4) (so called NCP) was fabricated by easily scalable and energy efficient method such as solution combustion synthesis. The obtained material was further ball-milled with carbon (NCP/C) to get nano-sized resultant particles. The orthorhombic crystal structure was confirmed by powder X-ray diffraction and purity of the material evidenced by X-ray photoelectron spectroscopy (XPS). The surface morphology and particle size of the materials were studied by scanning electron and transmission electron microscopic analyses. In cyclic voltammetric analysis, the cathode made up of NCP/C material showed a significant redox activity at 2.33 and 4.3 V. The NCP/C material exhibited a reversible intercalation with a discharge capacity of 36 mAh g−1 at 0.1 C and 50% capacity retention after 100 cycles in Na half-cell. To the best of our knowledge, the maricite α-NaCoPO4 cathode has been taken part in the charge/discharge process with the active sodium ions.

    更新日期:2020-01-11
  • Multinary copper-based chalcogenide semiconductor nanocrystals: synthesis and applications in light-emitting diodes and bioimaging
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-10
    Lijin Wang, Zhongyuan Guan, Aiwei Tang

    Abstract Colloidal semiconductor nanocrystals have been extensively used for illumination, displays, bioimaging, and other fields. However, the most extensively used Cd-based nanocrystals are toxic. Recently, non-toxic multinary copper-based chalcogenide semiconductor nanocrystals have been studied intensively. The mostly studied in these materials are ternary Cu–In–S nanocrystals which have large adjustable luminescence range, good luminescence efficiency, and excellent device applications. Therefore, this material has been the most potential candidates to replace Cd-based materials. To date, different synthetic methods have been developed to prepare ternary Cu–In–S nanocrystals, which include hot-injection, non-injection, thermal decomposition, and solvothermal route. In order to enhance the luminescence property, incorporating of Zn2+ or overgrowth of a ZnS shell is the comment ways that researchers often use. This review will introduce the synthesis methods of multinary copper-based chalcogenide semiconductor nanocrystals and their potential applications in quantum-dot light-emitting diodes and bioimaging fields. Finally, the conclusion and prospect are provided.

    更新日期:2020-01-11
  • A survey on dynamic modeling of manipulation of nanoparticles based on atomic force microscope and investigation of involved factors
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-09
    M. H. Korayem, H. Khaksar

    In this article, the collection of studies with regard to the modeling of nanomanipulation based on atomic force microscope (AFM) is discussed. To model the manipulation process, two-dimensional and three-dimensional models in the classical environment and molecular dynamics can be presented. The decisive factor in determining the solution’s type depends on the dimensions and application of manipulation. In general, however, benefiting from multiscale methods offers more realistic results from the inherent characteristics of AFM point of view. In addition, the manipulation process is examined empirically. Different parameters affect the process. Overall, these include the geometric properties of AFM, geometric properties and material of nanoparticles, process execution environment, initial impact of nanoparticles, contact mechanics, and roughness. The geometric parameters of AFM have less importance compared with other factors. The material and geometry of nanoparticles and environmental reaction play their most dominant role in contact and roughness equations as well as intermolecular forces. For instance, for softer nanoparticles, elastoplastic and viscoelastic contact theories are more suited. In contrast, in environments except vacuum and air, roughness models with more developed adhesion terms are better choices. Employing complex contact theories can provide us with permanent deformations, roughness, reduction in force, and critical indentation depth. In addition to the involved parameters in modeling the nanomanipulation process, path planning techniques for obtaining the optimal path and control of the AFM set for its exact execution are other influential notions.

    更新日期:2020-01-11
  • Molecular dynamics study of temperature and heating rate–dependent sintering of titanium nanoparticles and its influence on the sequent tension tests of the formed particle-chain products
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-09
    Jungmin Jeon, Shan Jiang, Farzin Rahmani, Sasan Nouranian

    Abstract Sintering of multiple single-crystal titanium (Ti) nanoparticles (NPs) during additive manufacturing by using ultrafast laser was simulated using molecular dynamics (MD). The aim was to better understand how factors such as sintering temperature and heating rate would influence the mechanical properties of the ultrafine-sized sintered products, i.e., Ti “NP-chains.” For this purpose, the effects of heating and strain rate on the tensile behavior of the final sintered products were studied in detail. Ti NP-chain precursors with weak neck connections were first created through solid-state sintering process at room temperature. They were later heated very rapidly to 800 K, 1200 K, or 1500 K with two different heating rates of 0.04 K/ps and 0.2 K/ps, and maintained at these high-temperature levels for 1 ns to mimic the fast temperature rise and short equilibration due to femtosecond/picosecond laser irradiation. The formed Ti NP-chains with different neck connection strengths were then cooled to 298 K. Those final NP-chains were subjected to uniaxial tension at three different strain rates of 0.001%/ps, 0.01%/ps, and 0.1%/ps. Our simulation results indicate a strong correlation between the tensile strength of the final NP-chain product and the heating rate during the previous short sintering process (including the ultrafast temperature rise and up to 1-ns high-temperature equilibration). A slower heating rate to a higher temperature level yields larger neck connection diameters in the final NP-chain product, resulting a higher tensile strength. Furthermore, our results demonstrate that high strain rates applied to the NP-chains with stronger neck connections result in an improvement in the tensile strength and ductility of the final products. In contrast, sintered products resulting from a lower temperature level show an elastic-brittle-damage behavior. Due to the weak neck connections and limited crystal sliding, the heating rate effect during sintering does not have a significant effect on the tensile strength.

    更新日期:2020-01-09
  • Core-shell structured carbon nanotubes/N-doped carbon layer nanocomposites for supercapacitor electrodes
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-08
    Chong Xie, Shenghui Yang, Xuequan Xu, Jian-Wen Shi, Chunming Niu

    N-Doped carbon layer–coated carbon nanotube (N-C/CNT) nanocomposites with stable core-shell structures were synthesized using a one-pot hydrothermal reaction. After high-temperature carbonization and KOH activation, the resultant N-C/CNT materials used as supercapacitor electrodes show high specific capacitance, good rate capability, and long cycle stability. The specific capacitance exhibits a high value of 322.1 F g−1 at 1 A g−1, and still maintains 200.7 F g−1, 168.7 F g−1, and 120.0 F g−1 at 5 A g−1, 10 A g−1, and 20 A g−1, respectively. During the 10,000-cycle testing at 5 A g−1, the specific capacitance was kept stable. The high performance of the supercapacitor electrodes could be attributed to the synergistic effect of the high specific surface area with fine pore structure, high electronic conductivity, and mechanical strength of CNT support and pseudocapacitance provided by doping N atoms in the carbon layer.

    更新日期:2020-01-09
  • Nanoparticle-based formulation of metallacarboranes with bovine serum albumin for application in cell cultures
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-08
    Benedikt Schwarze, Marta Gozzi, Carolin Zilberfain, Johanna Rüdiger, Claudia Birkemeyer, Irina Estrela-Lopis, Evamarie Hey-Hawkins

    We report on the unique self-assembling properties of one molybdacarborane (1) and two ruthenacarborane complexes (2 and 3) to spontaneously form nanoparticles alone or in combination with bovine serum albumin (BSA) in a 10:1 molar ratio (BSA:metallacarborane). The maverick behaviour of the metallacarboranes in aqueous media was investigated using several spectroscopic techniques, including nanoparticle tracking analysis, UV-Vis, fluorescence, Rayleigh light scattering and NMR spectroscopy, as well as MALDI-TOF mass spectrometry, from which a molecular picture of the nanoparticles was developed. The metallacarborane–albumin nanoparticles showed optimal stability in phosphate buffer (pH 7.4), retaining a mostly monomodal dispersion over 24 h, in contrast to the highly polydispersed nanoparticles of 1–3 alone. The three metallacarboranes were tested in vitro against the MCF-7 (breast carcinoma) cell line, using a BSA-free and a BSA-containing formulation. Surprisingly, the latter induced a significant increase in the cytotoxicity of 1, whereby it did not greatly affect the activity profile of 2 and 3. Finally, label-free confocal Raman imaging was applied to visualise the uptake of the metallacarboranes into single cells. The size of intracellular aggregates in the cytoplasm ranged from 300 nm to 5 μm. The discussed formulation concept is proposed as a new method to increase the bioactivity and the biological stability of poorly water-soluble (metalla)carboranes.

    更新日期:2020-01-08
  • Macrophage-like THP-1 cells show effective uptake of silica nanoparticles carrying inactivated diphtheria toxoid for vaccination
    J. Nanopart. Res. (IF 2.009) Pub Date : 2020-01-08
    Xinyue Huang, Danielle Paixão Cavalcante, Helen E Townley

    Nanoparticles may be used in vaccinology as an antigen delivery and/or an immunostimulant to enhance immunity. Porous silica has been identified as an effective adjuvant for more than a decade, and we have therefore investigated the take up rate by an immortalized macrophage-like cell line of a number of mesoporous silica nanoparticles (MSNPs) with differing diameter and pore size. The MSNPs were synthesized using a sol-gel reaction and post-synthesis removal of the template. The MSNPs showed a clear distribution in take up rate peaking at 217 nm, whereas a comparison with solid spherical nanoparticles showed a similar distribution peaking at 377 nm. The MSNPs were investigated before and after loading with antigen. Diphtheria toxoid was used as a proof-of-concept antigen and showed a peak macrophage internalization of 53.42% for loaded LP3 particles which had a diameter of 217.75 ± 5.44 nm and large 16.5 nm pores. Optimal MSNP sizes appeared to be in the 200–400 nm range, and larger pores showed better antigen loading. The mesoporous silica particles were shown to be generally biocompatible, and cell viability was not altered by the loading of particles with or without antigen.

    更新日期:2020-01-08
  • Ball-milling synthesis of ultrafine Na y Fe x Mn 1-x [Fe(CN) 6 ] as high-performance cathode in sodium-ion batteries
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-18
    Wenzhe Gong, Rui Zeng, Shang Su, Min Wan, Zhixiang Rao, Lihong Xue, Wuxing Zhang

    Manganese hexacyanoferrate (MnPBA) is a promising cathode material for sodium-ion batteries (SIBs). However, the poor electrical conductivity and the structural instability greatly hinder its practical applications in SIBs. In this work, a facile ball-milling method is used to synthesize the ultrafine NayFexMn1-x[Fe(CN)6] without additional additives. It shows that the ultrafine particles (~ 50 nm) favor the fast Na+ diffusion in MnPBA, while Fe-doping can enhance the electrical conductivity and suppress the structure distortion upon Na+ insertion/extraction. Thus, Fe-doped MnPBA demonstrates greatly improved electrochemical stability and kinetics. Especially, Fe-MnPBA/0.4 can deliver a specific capacity of 119 mA h g−1 at 1 C, corresponding to an energy density of ~ 380 Wh kg−1 in half-cell. Even at a current density of 30 C, its specific capacity still retains 86 mA h g−1. Our work provides a facile strategy to massively synthesize the PBAs on a large scale with excellent sodium-ion storage performance.

    更新日期:2019-12-19
  • Dispersibility and characterization of polyvinyl alcohol–coated magnetic nanoparticles in poly(glycerol sebacate) for biomedical applications
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-18
    Naiyin Zhang, Changlu Xu, Andro Azer, Huinan Liu

    Magnetic nanoparticles (MNPs) often require surface modification to improve their dispersion in other materials for biomedical applications. Polyvinyl alcohol (PVA) is a low-cost, water-soluble polymer that has been reported to be biocompatible and biodegradable. In this study, we investigated the properties of MNPs coated with different weight percentages of PVA (i.e., 0%, 3%, 5%, 10%, 20%, and 30%) in a one-pot synthesis, to determine the ideal weight percentage of PVA needed to achieve the best dispersion of MNPs in a model polymer matrix such as poly(glycerol sebacate) (PGS). The results showed that PVA was successfully coated onto the surface of MNPs, and all the MNPs with 0 to 30% nominal PVA exhibited spherical shape and similar crystallinity and superparamagnetism. The average diameter of PVA-coated MNPs was 8 ± 2 nm for 0, 3, 5, and 10% PVA-coated groups, but was slightly smaller for 20% and 30% groups with a respective diameter of 7 ± 2 nm and 6 ± 2 nm. The X-ray diffraction also confirmed that the particle sizes for 20% and 30% groups were slightly smaller than those of the other groups. When the MNPs were dispersed in the same PGS matrix and the weight percentages of PVA coating increased, less agglomerates of MNPs were observed and greater optical transmittance was achieved, indicating better dispersion. Overall, 30 wt.% of PVA coating used in MNP synthesis improved homogeneous dispersion of MNPs in a polymer matrix and reduced agglomeration. The effects of PVA content on the synthesized MNPs and the dispersion of MNPs reported in this study could be valuable for different applications when homogeneous dispersion of MNPs in a polymer matrix is desired.

    更新日期:2019-12-19
  • Functional Pd/reduced graphene oxide nanocomposites: effect of reduction degree and doping in hydrodechlorination catalytic activity
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-18
    Cristina Ruiz-Garcia, Yu Lei, Francisco Heras, Ana Laura Elías, Mauricio Terrones, Miguel A. Gilarranz

    Pd catalysts supported on carbon have interesting features for chlorophenols-bearing water treatment by hydrodechlorination, including high stability, activity, and tunable support. In this work, a set of materials based on reduced graphene oxide (rGO) with different degrees of reduction, surface oxygen groups, nitrogen doping, and specific surface area were decorated with Pd nanoparticles, with diameter average size between 5 and 50 nm. Ethanol, hydrazine monohydrate, and sodium borohydride were used as reducing agents, and Pd(AcO)2 was used as a Pd precursor to obtain Pd/rGO nanocomposites in our developed one-pot synthesis approach. A thorough characterization revealed that a similar degree of reduction was obtained for sodium borohydride at 25 °C and hydrazine at 60 °C, although hydrazine also led to nitrogen doping. Pd nanoparticles were homogenously nucleated on the surface of the GO and the obtained nanocomposites were tested as catalysts for hydrodechlorination of 4-chlorophenol in the aqueous phase. The materials with a higher degree of reduction showed the best specific catalytic activity at 70 °C. However, the turnover frequency (TOF) only increased with the reduction degree for the N-doped Pd/rGO, indicating the important role of the nitrogenous functionalities in the catalytic activity. Therefore, the N doping of Pd/rGO catalysts is a feasible strategy to synthesize catalysts highly active for hydrodechlorination.

    更新日期:2019-12-19
  • Correction to: Oxidative dissolution of silver nanoparticles by synthetic manganese dioxide investigated by synchrotron X-ray absorption spectroscopy
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-14
    Bruce A. Manning, Sushil R. Kanel, Edgar Guzman, Seth W. Brittle, Ioana E. Pavel

    The original version of this article unfortunately contained a mistake. The equation was incorrectly presented.

    更新日期:2019-12-17
  • Insight on nano-platinum-catalyzed dehydrogenation of quercetin in presence of peroxide
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-14
    Ranendu Sekhar Das, Bula Singh

    Quercetin (Qu), a noted polyphenolic flavonol molecule, exhibits remarkable antioxidant properties against bioenzymes like peroxidase and tyrosinase. However, it was found that under pH = 3.5–5.5 and room temperature, Qu cannot reduce hydrogen peroxide (HP) which is a well-perceived reactive oxygen species (ROS) responsible for oxidative stress. We found that in presence of noble-metal nano-particles, such redox interactions can be accomplished. We thus synthesized homogenous PVP-coated nano-platinum particles (PNP) to catalyze the oxidation of Qu by HP. On reaction, Qu is oxidized by HP to ortho-quinone (QQ) following the first-order kinetics. The observed rate constant, ko, gradually increases and tends to saturate with increasing [HP]T where T represents the analytical concentrations of the reactant. The saturation kinetics indicates that the activities of PNP resemble to that of bioenzymes and similarly, the nano-particles host the reactants on its active surface during the redox interactions. The estimated value of the kcat reveals that the extent of catalysis of even 10−10 M PNP is nearly comparable with the rate constants of oxidation of Qu in presence of enzymes like horseradish peroxidase and tyrosinase.

    更新日期:2019-12-17
  • Effect of diazotization and magnetic assembly on CNT dispersion observed with hardness and modulus measurement of their epoxy composite of low CNT volume fraction
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-09
    Shreya Trivedi, Melissa Rudolph, Yagmur Atescan, Jingyao Dai, Kayla Cooley, James H. Adair, Suzanne E. Mohney, Namiko Yamamoto

    Polymer composites with small amount of CNTs (< 5 wt%) have been studied as a light-weight wear-resistant material with low friction, among other applications, but their modulus improvement often plateaus or diminishes with increasing CNT fraction due to agglomeration. Here, polymer nanocomposites were fabricated with randomly oriented or aligned CNTs across their volume (up to 5 mm length) by CNT surface diazotization and by static magnetic field application (400 G for 40 min). With the improved CNT dispersion and thus less agglomeration, the reduced moduli of PNCs stayed improved with addition of up to 1 vol% (or 1.3 wt%) of CNTs. In this work, the PNCs with randomly oriented CNTs exhibited higher stiffness than the PNCs with magnetically aligned and assembled CNTs, indicating again the negative effect of CNT agglomeration on stiffness. In future, other CNT structuring methods with controlled inter-CNT contacts will be conducted to dissociate alignment from local agglomeration of CNTs and thus to simultaneously improve hardness and modulus of PNCs with small CNT addition.

    更新日期:2019-12-11
  • Motion of crystalline inclusions by interface diffusion in the proximity of free surfaces
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-09
    Roberto Bergamaschini, Brian A. Rosen, Francesco Montalenti, Jérôme Colin

    Triggered by experimental observations of nanometer-sized Ni precipitate motion in a La2O3 matrix, the migration and morphological evolution by interface diffusion of an initially circular two-dimensional precipitate located near the free surface of its matrix is numerically investigated by means of phase-field simulations. Considering isotropic interface and elastic energies, it is found that the precipitate migrates towards the free surface, suitably adapting its shape during the motion. The case of two precipitates located near the free surface is also considered as well as the problem of an evolving precipitate near a squared corner of the matrix free surfaces.

    更新日期:2019-12-11
  • Hydrolysis extraction of diosgenin from Dioscorea nipponica Makino by sulfonated magnetic solid composites
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-07
    Farong Zhang, Bowei Shen, Wenxiu Jiang, Hui Yuan, Hong Zhou

    Extraction of diosgenin from the rhizome of Dioscorea by catalytic hydrolysis over recyclable solid acids is one of the most enviromentally friendly ways for the conversion of biomass into chemicals. In this paper, a magnetic solid acid, Fe3O4@SiO2@NH-(CH2)2-NH2@SO3H with the particle size of about 80 nm, was synthesized by using Fe3O4 (~ 20 nm) as a magnetic core and then coated orderly with tetraethyl orthosilicate (TEOS) and N-{3-(Trimethoxysilyl) propyl} ethylenediamine (TMPED) by sol-gel reactions in water/ethanol solution, followed by the sulfonation of chlorosulfonic acid. The solid acid was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). The content of acidic sites on the surface of the solid acid was 1.01 mmol/g, measured by back titration method. The prepared solid acid was used to hydrolyze and extract diosgenin from Dioscorea nipponica Makino (DNM). The results show that the magnetic solid acid has higher hydrolysis activity than 2.5 M hydrochloric acid under same hydrolysis conditions, at 110 °C for 5 h. In addition, the magnetic solid acid can be easily separated from the reaction mixture by the application of a magnet and reused several times without significant activity loss. This work has a potential application value for the extraction of diosgenin from plants.

    更新日期:2019-12-11
  • Controllable synthesis of novel luminescent CuFeS 2 quantum dots with magnetic properties and cation sensing features
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-05
    Nengtao Wu, Xingyu Liu, Min Zeng, Jinwei Gao, Xubing Lu, Zhi Zeng, Yuhui Zheng

    Since Cu2+ and Fe3+ ions have been considered as bioactive cations in oxygen transport and enzymatic reactions, the development of reliable ways for the monitoring of the two species will be highly desirable. But the optical stability of conventional organic chromophores needs to be improved. Therefore, the employment of quantum dots (quantum dots are abbreviated to be QDs) such as ternary CuFeS2 QDs for the purpose of sensing has been reported in this study. CuFeS2 QDs were synthesized by using oleylamine as the stabilizer at 180 °C and the particle size was around 2–3 nm. The monodispersed quantum dots with tetragonal chalcopyrite crystalline structure were identified. The corresponding excitation and emission wavelengths of the QDs were monitored at 372 and 458 nm. Magnetic properties were analyzed via applied magnetic field ranging between −6000 and 6000 Oe at 300 K and the ferromagnetic phase was verified. In this report, CuFeS2 QDs has been used as an optical probe to detect the metal ions with high sensitivity, selectivity and fast responses. Two linear equations can be obtained in the range from 0 to 30 μM for Cu2+ and from 0 to 45 μM for Fe3+ (detection limits: Cu2+, 1.98 μM; Fe3+, 2.15 μM). These results may provide promising applications in cation sensing fields.

    更新日期:2019-12-11
  • Promotion of dispersion and anticancer efficacy of hydroxyapatite nanoparticles by the adsorption of fetal bovine serum
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-03
    Yi Sun, David Devore, Xiaoyu Ma, Yuan Yuan, Joachim Kohn, Jianchao Qian

    The biocompatibility and anticancer effect of hydroxyapatite nanoparticles (HAPNs) are compelling and promising in cancer nanomedicine. However, the essential role of fetal bovine serum (FBS) in a biological environment possibly determining the state of agglomeration and intracellular fate of HAPNs (length: ~ 60 nm; width: ~ 20 nm) has never been studied. Here, we investigated the importance of FBS in agglomeration and cell response of HAPNs in human osteosarcoma MG-63 cells. Protein adsorption on the surface of HAPNs after mixing with different concentrations of FBS was confirmed using transmission electron microscope (TEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, quartz crystal microbalance with dissipation (QCM-D), and thermogravimetric analysis (TG). The adsorption of serum protein improved dispersed state and stabilization of HAPNs, which was evidenced by dynamic light scattering (DLS), inverted microscope, and scanning electron microscope (SEM). More specifically, the agglomerate size of HAPNs in cell culture medium without FBS was above 1400 nm, while the agglomerate size of HAPNs with 10% FBS was decreased to about 200 nm and maintained for at least five days. Meanwhile, serum protein adsorption on HAPN surface enhanced cellular uptake and anticancer efficacy of HAPNs in MG-63 cells.

    更新日期:2019-12-11
  • The comparison of Pr 3+ :LaF 3 and Pr 3+ :LiYF 4 luminescent nano- and microthermometer performances
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-03
    M. S. Pudovkin, S. L. Korableva, D. A. Koryakovtseva, E. V. Lukinova, A. V. Lovchev, O. A. Morozov, V. V. Semashko

    In the present work, we make a comparison of Pr3+:LaF3 and Pr3+:LiYF4 luminescent nano- and microthermometer performances. We studied Pr3+:LaF3 nanoparticles, synthesized via co-precipitation method (further Pr3+:LaF3 (co-precipitation)), Pr3+:LaF3 nanoparticles, synthesized via hydrothermal method (further Pr3+:LaF3 (hydrothermal)), and Pr3+:LaF3 microparticles as well as Pr3+:LiYF4 nanoparticles, synthesized via hydrothermal method (further Pr3+:LiYF4 nanoparticles) and Pr3+:LaF3 microparticles. According to the X-ray diffraction, Pr3+:LaF3 (co-precipitation) and Pr3+:LaF3 (hydrothermal) nanoparticles are hexagonal-structured nanocrystals. Pr3+:LiYF4 nanoparticles are tetragonal-structured nanocrystals. The average diameters of Pr3+:LaF3 (co-precipitation), Pr3+:LaF3 (hydrothermal), and Pr3+:LiYF4 nanoparticles are 13.9, 19.4, and 33.3 nm, respectively. The Pr3+:LaF3 (co-precipitation) and Pr3+:LaF3 (hydrothermal) nanoparticles demonstrate broadband luminescence caused by crystal lattice defects (luminescence background). This luminescence background notably decreases the temperature sensitivity of these samples. The luminescent background removing procedure significantly complicates the signal processing procedure. Pr3+:LaF3 microparticles, Pr3+:LiYF4 nanoparticles, and Pr3+:LaF3 microparticles do not demonstrate this undesirable phenomenon. The absolute temperature sensitivity Sa of Pr3+:LiYF4 nanoparticles, Pr3+:LiYF4 microparticles, and Pr3+:LaF3 microparticles at 300 K are 0.0117 ± 0.0010, 0.0106 ± 0.0010, and 0.0102 ± 0.0012 K−1, respectively. Although the values of Sa are very close for these samples, the nanosized dimensionality of Pr3+:LiYF4 nanoparticles allows achieving high spatial resolution and expanding the fields of application of Pr3+:LiYF4 nanoparticles.

    更新日期:2019-12-11
  • In situ preparation of Ag 3 VO 4 /MOFs composites with enhanced visible-light-driven catalytic activity
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-12-02
    Boyin Zhai, Ying Chen, Yuning Liang

    In this work, we have fabricated a novel Ag3VO4/MIL-125(Ti) photocatalyst by in situ deposition method, which is characterized by XRD, SEM, TEM, FT-IR, XPS, TG, BET, UV-Vis DRS, and PL. The photocatalytic degradation activity of as-prepared materials was studied via decomposing Rh B, and the possible mechanism of photocatalytic degradation was put forward. The result displayed that the specific surface area of a series of composites is larger than that of the single Ag3VO4 (SBET = 9.374 m2/g), and the photocatalytic efficiency is much higher than that of pure Ag3VO4 and MIL-125(Ti). Among them, the photocatalytic activity of AM-3 composite (SBET = 89.734 m2/g, Eg = 2.13 eV) is the highest, about 3.7 times and 13.1 times of pure Ag3VO4 and MIL-125(Ti), respectively. At the same time, the Ag3VO4/MIL-125(Ti) composite can maintain a stable photocatalytic activity and structure after four cycles.

    更新日期:2019-12-11
  • In vivo targeting of breast cancer with peptide functionalized GQDs/hMSN nanoplatform
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-30
    Xinyue Yao, Chuntong Qian, Yuanyuan Zhong, Shian Sun, Huanghuang Xu, Dongzhi Yang

    Graphene quantum dots capped in hollow mesoporous silica nanoparticles (GQDs@hMSN) exhibited great potential in medical applications due to its good optical properties and high drug loading capacity. Compared with antibodies, peptide has a better affinity with target proteins. Herein, we demonstrated efficient targeting of triple-negative breast cancer with GQDs@hMSN, which was conjugated to a peptide ligand, F3 against nucleolin, to form GQDs@hMSN-F3. The core/shell GQDs@hMSN and GQDs@hMSN-F3 had diameters of 100 nm and 130 nm, respectively, based on transmission electron microscope (TEM) and dynamic laser scattering (DLS) measurement. Doxorubicin (DOX) was loaded onto GQDs@hMSN with a relatively high loading capacity. Systematic in vitro and in vivo studies were performed to investigate the targeting specificity and tissue distribution of GQDs@hMSN conjugates. Fluorescence microscopy examination and flow cytometry confirmed the targeting specificity of F3-attached GQDs@hMSN conjugates against cell nucleolin. A more potent uptake of GQDs@hMSN-F3 in MDA-MB-231 nodules was witnessed when compared with that of non-targeted GQDs@hMSN. Based on the findings from cellular targeting and in vivo fluorescence imaging, F3-attached GQDs@hMSN conjugates had the potential to serve as an image-guidable, tumor-selective cargo delivery nanoplatform.

    更新日期:2019-12-11
  • Morphology engineering and growth mechanism of ZnS nanostructures synthesized by solvothermal process
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-30
    Sema Ebrahimi, Benyamin Yarmand

    Zinc sulfide (ZnS) nanostructures with various morphologies play an imperative role in optoelectronic applications. In this study, different ZnS nanostructures with well-defined morphologies were synthesized in a controlled manner by a low-temperature solvothermal method using the binary solvent mixtures of ethylenediamine and water (EN/W). Controlling the content of EN and the growth temperature, ZnS nanostructures including nanoflowers, nanoflakes, nanorods, and hexagonal nanoplates were produced at a very low temperature ranging from 100 °C to 180 °C during short reaction times of 2 h and 6 h with excellent reproducibility. X-ray diffraction patterns of the nanostructures considerably revealed the single crystalline nature with a pure wurtzite phase of ZnS even at the low growth temperature having the average crystallite size in the range of 12.8–25.0 nm. The morphology evolution of the samples showed that there is a strong correlation between the morphologies of the ZnS nanostructures and the variations of both the growth temperature and reaction solvent. Based on the experimental results, a growth mechanism was also proposed for all the ZnS nanostructures with different morphologies. A sharp absorption band-edge was found for the ZnS nanostructures, in which the optical bandgap energy was laid ranging from 3.97 eV to 4.09 eV due to the quantum confinement effect. All the samples featured a broad asymmetrical photoluminescence emission with multiple peaks, corresponding to excitonic and trapped luminescence centers. The effect of morphology on the optoelectronic performance resulted in a tremendous photoresponsivity and an excellent time-response switching behavior in UV region.

    更新日期:2019-12-11
  • Rutile nanoparticles in anatase TiO 2 thin films to improve their water splitting performance
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-28
    Ruijin Hong, Cao Deng, Ming Jing, Jingqi Shi, Zhengwang Li, Chunxian Tao, Dawei Zhang

    Rational design and fabrication of phase junction is an important way and strategy to enhance the photocatalytic performance. In this paper, rutile/anatase phase junction is obtained in rutile nanoparticles decorated anatase thin film by laser ablation. The hydrogen generation of rutile/anatase composite film is 49.6 μL, which is remarkably higher than that of both anatase thin film and rutile decorated layer. The quantity of phase junctions between rutile and anatase is considered as a key factor of photocatalytic improvement by varying the amount of rutile nanoparticles. Moreover, the excellent photocatalytic stability of rutile/anatase composite film is also exhibited.

    更新日期:2019-12-11
  • Quantifying the nanoparticles concentration in nano-PCM
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-28
    Kumar Venkateshwar, Naveen Joshy, Hari Simha, Shohel Mahmud

    Nanoparticle-enhanced phase change materials (i.e., nano-PCM) exhibit improved heat transfer and have been extensively investigated because of their potential application to latent heat thermal energy storage systems. However, the sedimentation of nanoparticles is a concern, as observed from numerous experimental investigations, which limits the application of nano-PCMs in an operation with many repetitive cycles. The studies of sedimentation of nanoparticles have been limited to qualitative observations, and the quantitative studies are primarily limited to the sedimentation of nanoparticles with time in nanofluids, with few studies on the sedimentation in nano-PCM. The different potential techniques to quantify the concentration of nanoparticles after each thermal cycle have been discussed. A novel image analysis technique was used to measure the concentration and non-uniformity in the dispersion of nanoparticles after each thermal cycle. The understanding of effect of different thermophysical properties of PCM and nanoparticles on the stability of the nano-PCM is essential for the development of stable nano-PCM for their practical applications. The present study analyzes the effect of size, density, and concentration of nanoparticles, along with the effect of viscosity, density, and difference in the density in solid and liquid phase of PCM on the stability of nano-PCM. Two different concentrations of copper oxide (<50 nm) and iron oxide (50–100 nm) nanoparticles in Rubitherm35 HC and CuO in coconut oil were studied. The larger density difference in the solid and liquid state of PCM leads to higher sedimentation. The effect of particle size dominated over nanoparticles density on sedimentation process.

    更新日期:2019-12-11
  • Synthesis and performances evaluation of the spindle-shaped calcium hydroxide nanomaterials for thermochemical energy storage
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-28
    Caifeng Huang, Min Xu, Xiulan Huai

    Thermochemical energy storage is a promising alternation in heat recovery application and concentrated solar power plants. The present work focuses on the influence of morphology and porosity of Ca(OH)2 nanomaterials on their thermochemical energy storage performances. Firstly, the Ca(OH)2 nanoparticles with the morphologies of spindle and hexagonal structure were synthesized by the deposition-precipitation method, and their performances were evaluated by thermogravimetric analysis together with three kinds of commercial nanoparticles. The BET tests demonstrate that the self-made spindle-shaped Ca(OH)2 has the highest BET-specific surface area and pore volume among these five nanomaterials. Secondly, the thermochemical energy storage performance evaluation of these materials showed that the spindle-shaped Ca(OH)2 exhibited the best heat storage and output capacities (about 1300 kJ/kg), thus bringing a convenient route in production of Ca(OH)2 with higher energy storage density. Finally, after ten dehydration/hydration cycles, the conversions of spindle-shaped Ca(OH)2 remained at above 70%.

    更新日期:2019-12-11
  • Preparation of Ag@SiO 2 @NH 2 core-shell nanocomposites for the fluorescence enhancement of carbon quantum dots
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-27
    Qian Wu, Zhulong Zhou, Taohong Zhang, Ming Zhou

    In this paper, the fluorescence enhancement phenomenon of carbon quantum dots (C-QDs) via metal fluorescence effect has been investigated. Firstly, uniform Ag nanoparticles was prepared, which theoretically can supply a strong enhancement effect with a diameter as small as 20 nm. Then SiO2 shell was utilized to control the distance between Ag core and C-QDs while surface charge of as-synthesized Ag@SiO2 was further modified to bond C-QDs via electrostatic effect. Four different kinds of SiO2 shell, with thickness 12 nm, 15 nm, 20 nm, and 27 nm, were synthesized to study the enhancement effect of distance. With the increase of SiO2 shell, the fluorescence of Ag@SiO2@NH2-C-QDs nanocomposites rise first but then fall while the sample with the 20-nm shell obtained the best enhancement effect as high as 3.92-fold. Surface charge vibration of metal particles was used to explain this phenomenon.

    更新日期:2019-12-11
  • Particle size control of monodispersed spherical nanoparticles with MCM-48-type mesostructure via novel rapid synthesis procedure
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-25
    Shewaye Yismaw, Richard Kohns, Denise Schneider, David Poppitz, Stefan G. Ebbinghaus, Roger Gläser, Ulrich Tallarek, Dirk Enke

    Monodispersed spherical silica nanoparticles with a cubic mesostructure were synthesized in a fast and innovative way using triethanolamine (TEA) and the triblock copolymer Pluronic® F127 as particle growth inhibitors to control the particle size in a range from 420 to 62 nm. In this study, we described a synthesis of mesoporous silica nanoparticles (MSNs) with MCM-48 structure at room temperature with adequate control of particle monodispersity, shape, and size using TEA. Based on particle characterization, TEA can efficiently act as catalyst and at the same time as particle growth controlling additive. A mixture of TEA and Pluronic® F127 additives was used to obtain very small MSNs (62 nm), whereby the quality of MCM-48 silica is associated with the composition of the additives used and thus also with the final particle size. A finely dispersed and high-quality MCM-48 material with ~ 100% yield, excellent textural properties, and a particle size of 295 nm was synthesized within only 35 min using excess TEA as particle size controlling and dispersion agent together with ammonia as additional catalyst. Solvent extraction combined with ion exchange removed the surfactant efficiently. All prepared MSNs showed good textural properties, tunable particle sizes with narrow size distributions, and good dispersity in water, which make them highly promising as carriers for biomolecules in biomedical applications.

    更新日期:2019-12-11
  • Enhanced adsorption of methylene blue on chemically modified graphene nanoplatelets thanks to favorable interactions
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-25
    Rabita Mohd Firdaus, Noor Izzati Md Rosli, Jaafar Ghanbaja, Brigitte Vigolo, Abdul Rahman Mohamed

    In the present study, the used graphene nanoplatelets (GNPs) are of high structural quality offering the opportunity to modify the adsorbent/adsorbate interactions. Their chemical modification by simple acid oxidation leads to their facile dispersion in water. Morphological, structural, and chemical properties of the functionalized GNPs are deeply investigated by a set of complementary characterization techniques. The parametric investigation including effects of initial concentration, contact time, solution pH, and temperature of methylene blue (MB) adsorption allows to identify those being relevant for MB removal enhancement. MB adsorption is found to increase with contact time, solution temperature, and acidic pH. The nature of the MB-GNP interactions and the possible adsorption mechanisms, relatively little understood, are here particularly studied. MB-GNP adsorption is shown to follow a Langmuir isotherm and a pseudo-first-order kinetic model. The adsorption capacity of MB on the chemically modified GNPs (qm = 225 mg/g) with respect to the external surface is relatively high compared to other carbon nanomaterials. Such adsorbent certainly merits further consideration for removal of other dyes and heavy metals from wastewaters.

    更新日期:2019-12-11
  • Polycarboxyl metal–organic framework UiO-66-(COOH) 2 as efficient desorption/ionization matrix of laser desorption/ionization mass spectrometry for selective enrichment and detection of phosphopeptides
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-23
    Yingchen Yang, Yan Xia

    Specific enrichment and efficient detection of phosphopeptides are important for phosphoproteomic analysis. Metal–organic frameworks (MOFs) have been proved to be effective enrichment materials combined with the analysis of mass spectrometry. In this work, we have developed a polycarboxylic group MOF-UiO-66-(COOH)2 used as both efficient enrichment material for phosphopeptides and efficient desorption/ionization matrix of laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) without elution. The crystal is spherical and the particle size is about 200 nm. When using it as enrichment material and MS matrix, phosphopeptides of β-casein can be efficiently detected under superior low detection limits of 1 fmol μL−1, and at an extremely low molar ratio of phosphoprotein/non-phosphoprotein (1:2000) mixtures, there are still four phosphopeptides that can be observed. When detecting real samples, most phosphopeptides of non-fat milk and human saliva can be observed, which is comparable with the literature.

    更新日期:2019-12-11
  • Silver nanotriangles and chemotherapy drugs synergistically induce apoptosis in breast cancer cells via production of reactive oxygen species
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-23
    Peidang Liu, Huiquan Yang, Wenbin Chen, Jing Zhao, Dongdong Li

    Chemotherapy is increasingly used in breast cancer treatment; however, drug resistance remains the major limitation and challenge of present chemotherapy. Previous studies indicated that the combination of nanomaterials and chemotherapy drug could overcome such resistance and exhibit a synergistic anticancer effect. The purpose of this study was to evaluate the antibreast cancer effect of cyclophosphamide, gemcitabine, 5-fluorouracil, oxaliplatin, or doxorubicin combined with silver nanotriangles (AgNTs), and screen out the drug with the most broad-spectrum and strongest synergistic activity. Transmission electron microscopy image showed that the synthesized AgNTs were triangular and truncated triangular in shape with a mean edge length of 126 nm. The synergistic antibreast cancer effect of AgNTs plus cyclophosphamide or gemcitabine was found to be cell type–specific, while 5-fluorouracil, oxaliplatin, and doxorubicin displayed synergistic effects with AgNTs on viabilities of various breast cancer cell lines (MDA-MB-231, MCF-7, and 4T1), and doxorubicin was the strongest in general. Furthermore, the synergism was proved to mainly result from reactive oxygen species–mediated cell apoptosis. These findings could potentially be exploited for new highly efficient combination treatment of breast cancer.

    更新日期:2019-12-11
  • Quantum mechanical study of chemical reactivity of graphene doped with iron in aqueous medium for applications in biomedicine
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-23
    Ernesto López-Chávez, Alberto Garcia-Quiroz, Yesica A. Peña-Castañeda, José A. I. Díaz-Góngora, Fray de Landa Castillo-Alvarado

    This work was made using the density functional theory (DFT) computational method, applying it to a graphene-doped theoretical structure with iron atoms, studied as an isolated molecular system in aqueous medium, using the functional GGA PW91, under Material Studio computational platform, to get the chemical reactivity properties of graphene doped with iron (called Fe-G) that can provide knowledge of binding of biomolecules such as peptides, enzymes, and lipids. We present some electrochemistry properties such electron affinity (EA) and ionization potential (IP). The chemical reactivity was characterized by global indicators such as, chemical potential, chemical hardness, and chemical electrophilicity index. In order to find the zones most prone to nucleophilic, electrophilic, and radical attacks, the calculation of the HOMO-LUMO boundary orbital was carried out, and the corresponding energies were obtained. Local reactivity was studied by using local selectivity descriptors such as Fukui indices.

    更新日期:2019-12-11
  • Nanoscale thermal transport in epoxy matrix composite materials reinforced with carbon nanotubes and graphene nanoplatelets
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-23
    Junjie Chen, Baofang Liu, Longfei Yan

    The technology related to hybrid filler-reinforced polymer matrix composite materials is growing at a high rate with increasing interest and usage. This study presents a way of increasing the thermal conductivity of polymer matrix composites by the use of a hybrid filler consisting of carbon nanotubes and graphene nanoplatelets and preliminarily clarifies the mechanisms that lead to the synergistic reinforcement of composite thermal conductivity at the nanoscale. The focus of this study was upon the fundamental relationships between nanometer-scale reinforcement structures and macroscopic composite thermal properties. The benefits and limitations associated with the incorporation of the hybrid filler into an epoxy matrix were evaluated. The results indicated that there exists an evident synergistic reinforcing effect between carbon nanotubes and graphene nanoplatelets on composite thermal conductivity. A significant increase has been gained in composite thermal conductivity, but low loading is required in order to exploit the benefits derived from the unique structure of the hybrid filler. Filler loading must be controlled very accurately in order to ensure that a critical threshold is not reached, beyond which there is a decrease in thermal conductivity, compared to that of graphene nanoplatelet-reinforced composites. The synergistic reinforcing benefits to composite thermal conductivity and is derived from effective conducting pathways formed between carbon nanotubes and graphene nanoplatelets within polymer matrices. The results can offer practical guidance on how to improve thermal transport properties for polymer matrix composite materials.

    更新日期:2019-12-11
  • A review on virus protein self-assembly
    J. Nanopart. Res. (IF 2.009) Pub Date : 2019-11-23
    Abha Chaudhary, Ram Dhan Yadav

    Proteins, the important biomacromolecules, have been magnificently applied to construct the protein self-assembled nanomaterials. The viruses are the largest reservoir of genetic material on the planet; the virus coat protein self-assemble is with very symmetric nanostructures that fascinate abundant interest and is one of the most fast emerging research area owing to its significant applications in practically every important region, i.e. in energy harvesting, in synthesis of nanoparticles, nanotubes, nanodrugs/medicine, nanobiotechnology, and superstructures. This review highlights the most recent studies on virus protein self-assembly with a focus on the recent literature about the effect of amino acids, pH, and charge on the virus protein self-assembly, recent examples of virus templates used for the self-assembly, and the problems occurring at the time of self-assembly that are also discussed.

    更新日期:2019-12-11
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