Nanomaterials

11 pages, 871 KiB

Open AccessEditor’s ChoiceArticle

Hybrid Polyethylene Glycol/Sodium Metaphosphate Composites Prepared via Coacervation

by Bruno Poletto Rodrigues, Guilherme Nunes Braga Maurício de Macedo, Yang Xia, Andrea Balducci and Lothar Wondraczek

Nanomaterials 2022, 12(3), 528; https://doi.org/10.3390/nano12030528 - 3 Feb 2022

Viewed by 2166

Abstract

We report on the fabrication and characterization of homogeneous, monophasic sodium metaphosphate and polyethylene glycol hybrid composites achieved via coacervation in aqueous solution. After separation and drying, an amorphous plastic solid is formed, composed mostly of hydrated sodium phosphate moieties amalgamated with polyethylene [...] Read more.

We report on the fabrication and characterization of homogeneous, monophasic sodium metaphosphate and polyethylene glycol hybrid composites achieved via coacervation in aqueous solution. After separation and drying, an amorphous plastic solid is formed, composed mostly of hydrated sodium phosphate moieties amalgamated with polyethylene glycol chains. These composites are largely X-ray amorphous and can contain up to 8 weight percent of polymer. Impedance spectroscopic measurements reveal DC conductivity values of 12 μS/m at room temperature, an enhancement of three orders of magnitude when compared to glassy sodium metaphosphate, and the presence of the polyethylene glycol is reflected in the equivalent circuit and ionic hopping analyses. Full article

(This article belongs to the Section Nanocomposite Materials)

► Show Figures

Graphical abstract

14 pages, 5828 KiB

Open AccessEditor’s ChoiceArticle

Increasing Magnetic Anisotropy in Bimetallic Nanoislands Grown on fcc(111) Metal Surfaces

by Sergio Vlaic, Dimitris Mousadakos, Safia Ouazi, Stefano Rusponi and Harald Brune

Nanomaterials 2022, 12(3), 518; https://doi.org/10.3390/nano12030518 - 2 Feb 2022

Cited by 2 | Viewed by 2026

Abstract

The magnetic properties and the atomic scale morphology of bimetallic two-dimensional nanoislands, epitaxially grown on fcc(111) metal surfaces, have been studied by means of Magneto-Optical Kerr Effect and Scanning Tunneling Microscopy. We investigate the effect on blocking temperature of one-dimensional interlines appearing in [...] Read more.

The magnetic properties and the atomic scale morphology of bimetallic two-dimensional nanoislands, epitaxially grown on fcc(111) metal surfaces, have been studied by means of Magneto-Optical Kerr Effect and Scanning Tunneling Microscopy. We investigate the effect on blocking temperature of one-dimensional interlines appearing in core-shell structures, of two-dimensional interfaces created by capping, and of random alloying. The islands are grown on Pt(111) and contain a Co-core, surrounded by Ag, Rh, and Pd shells, or capped by Pd. The largest effect is obtained by Pd capping, increasing the blocking temperature by a factor of three compared to pure Co islands. In addition, for Co-core Fe-shell and Co-core Fe_xCo_1−x-shell islands, self-assembled into well ordered superlattices on Au(11,12,12) vicinal surfaces, we find a strong enhancement of the blocking temperature compared to pure Co islands of the same size. These ultra-high-density (15 Tdots/in²) superlattices of CoFe nanodots, only 500 atoms in size, have blocking temperature exceeding 100 K. Our findings open new possibilities to tailor the magnetic properties of nanoislands. Full article

(This article belongs to the Special Issue Epitaxial Self-Assembly of Magnetic Nanostructures)

► Show Figures

Figure 1

10 pages, 2030 KiB

Open AccessEditor’s ChoiceArticle

Plasmon-Induced Transparency for Tunable Atom Trapping in a Chiral Metamaterial Structure

by Zhao Chen, Yaolun Yu, Yilin Wang, Zhiling Hou and Li Yu

Nanomaterials 2022, 12(3), 516; https://doi.org/10.3390/nano12030516 - 1 Feb 2022

Cited by 4 | Viewed by 2155

Abstract

Plasmon-induced transparency (PIT), usually observed in plasmonic metamaterial structure, remains an attractive topic for research due to its unique optical properties. However, there is almost no research on using the interaction of plasmonic metamaterial and high refractive index dielectric to realize PIT. Here, [...] Read more.

Plasmon-induced transparency (PIT), usually observed in plasmonic metamaterial structure, remains an attractive topic for research due to its unique optical properties. However, there is almost no research on using the interaction of plasmonic metamaterial and high refractive index dielectric to realize PIT. Here, we report a novel nanophotonics system that makes it possible to realize PIT based on guided-mode resonance and numerically demonstrate its transmission and reflection characteristics by finite element method simulations. The system is composed of a high refractive-index dielectric material and a two-dimensional metallic photonic crystal with 4-fold asymmetric holes. The interaction mechanism of the proposed structure is analyzed by the coupled-mode theory, and the effects of the parameters on PIT are investigated in detail. In addition, we first consider this PIT phenomenon of such fields on atom trapping (⁸⁷Rb), and the results show that a stable 3D atom trapping with a tunable range of position of about ~17 nm is achieved. Our work provides a novel, efficient way to realize PIT, and it further broadens the application of plasmonic metamaterial systems. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

► Show Figures

Figure 1

12 pages, 2984 KiB

Open AccessEditor’s ChoiceArticle

Cancer Cytotoxicity of a Hybrid Hyaluronan-Superparamagnetic Iron Oxide Nanoparticle Material: An In-Vitro Evaluation

by Yen-Lan Chang, Pei-Bang Liao, Ping-Han Wu, Wei-Jen Chang, Sheng-Yang Lee and Haw-Ming Huang

Nanomaterials 2022, 12(3), 496; https://doi.org/10.3390/nano12030496 - 31 Jan 2022

Cited by 7 | Viewed by 3443

Abstract

While hyaluronic acid encapsulating superparamagnetic iron oxide nanoparticles have been reported to exhibit selective cytotoxicity toward cancer cells, it is unclear whether low-molecular-weight hyaluronic acid-conjugated superparamagnetic iron oxide nanoparticles also display such cytotoxicity. In this study, high-molecular-weight hyaluronic acid was irradiated with γ-ray, [...] Read more.

While hyaluronic acid encapsulating superparamagnetic iron oxide nanoparticles have been reported to exhibit selective cytotoxicity toward cancer cells, it is unclear whether low-molecular-weight hyaluronic acid-conjugated superparamagnetic iron oxide nanoparticles also display such cytotoxicity. In this study, high-molecular-weight hyaluronic acid was irradiated with γ-ray, while Fe₃O₄ nanoparticles were fabricated using chemical co-precipitation. The low-molecular-weight hyaluronic acid and Fe₃O₄ nanoparticles were then combined according to a previous study. Size distribution, zeta potential, and the binding between hyaluronic acid and iron oxide nanoparticles were examined using dynamic light scattering and a nuclear magnetic resonance spectroscopy. The ability of the fabricated low-molecular-weight hyaluronic acid conjugated superparamagnetic iron oxide nanoparticles to target cancer cells was examined using time-of-flight secondary ion mass spectrometry and T2* weighted magnetic resonance images to compare iron signals in U87MG human glioblastoma and NIH3T3 normal fibroblast cell lines. Comparison showed that the present material could target U87MG cells at a higher rate than NIH3T3 control cells, with a viability inhibition rate of 34% observed at day two and no cytotoxicity observed in NIH3T3 normal fibroblasts during the three-day experimental period. Supported by mass spectrometry images confirming that the nanoparticles accumulated on the surface of cancer cells, the fabricated materials can reasonably be suggested as a candidate for both magnetic resonance imaging applications and as an injectable anticancer agent. Full article

(This article belongs to the Special Issue Functionalized Magnetic Nanomaterials)

► Show Figures

Figure 1

16 pages, 2441 KiB

Open AccessEditor’s ChoiceArticle

Phase-Selective Synthesis of Anatase and Rutile TiO₂ Nanocrystals and Their Impacts on Grapevine Leaves: Accumulation of Mineral Nutrients and Triggering the Plant Defense

by László Kőrösi, Balázs Bognár, Gyula Czégény and Simone Lauciello

Nanomaterials 2022, 12(3), 483; https://doi.org/10.3390/nano12030483 - 29 Jan 2022

Cited by 5 | Viewed by 3225

Abstract

Titanium dioxide nanocrystals (TiO₂ NCs), through their photocatalytic activity, are able to generate charge carriers and induce the formation of various reactive oxygen species (ROS) in the presence of O₂ and H₂O. This special feature makes TiO₂ an [...] Read more.

Titanium dioxide nanocrystals (TiO₂ NCs), through their photocatalytic activity, are able to generate charge carriers and induce the formation of various reactive oxygen species (ROS) in the presence of O₂ and H₂O. This special feature makes TiO₂ an important and promising material in several industrial applications. Under appropriate antioxidant balancing, the presence of ROS is crucial in plant growth and development, therefore, the regulated ROS production through the photocatalytic activity of TiO₂ NCs may be also exploited in the agricultural sector. However, the effects of TiO₂ NCs on plants are not fully understood and/or phase-pure TiO₂ NCs are rarely used in plant experiments. In this work, we present a phase-selective synthesis of TiO₂ NCs with anatase and rutile crystal phases. The nanomaterials obtained were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance UV-Vis spectroscopy, and electron paramagnetic resonance spectroscopy (EPR). In field experiments, Vitis vinifera cv. Cabernet Sauvignon leaves developed under natural sunlight were treated with aqueous dispersions of TiO₂ NCs at concentrations of 0.001, 0.01, 0.1, and 1 w/v%. The effect of the applied nanocrystals was characterized via leaf photochemistry, mineral nutrient contents, and pyridoxine levels. We found that stress responses of grapevine to anatase and rutile NCs treatments are different, which can be related to the different ROS profiles of the two polymorphs. Our results indicate that TiO₂ NCs may be utilized not only for direct pathogen inactivation but also for eliciting plant defense mechanisms. Full article

(This article belongs to the Special Issue Synthesis and Application of Antimicrobial Nanomaterials)

► Show Figures

Figure 1

9 pages, 1973 KiB

Open AccessEditor’s ChoiceArticle

Stochastic Microsensors Based on Carbon Nanotubes for Molecular Recognition of the Isocitrate Dehydrogenases 1 and 2

by Raluca-Ioana Stefan-van Staden, Catalina Cioates Negut, Sorin Sebastian Gheorghe and Paula Sfirloaga

Nanomaterials 2022, 12(3), 460; https://doi.org/10.3390/nano12030460 - 28 Jan 2022

Cited by 3 | Viewed by 2426

Abstract

Two three-dimensional (3D) stochastic microsensors based on immobilization of protoporphyrin IX (PIX) in single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) decorated with copper (Cu) and gold (Au) nanoparticles were designed and used for the molecular recognition of isocitrate dehydrogenase 1 (IDH1) [...] Read more.

Two three-dimensional (3D) stochastic microsensors based on immobilization of protoporphyrin IX (PIX) in single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) decorated with copper (Cu) and gold (Au) nanoparticles were designed and used for the molecular recognition of isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) in biological samples (brain tumor tissues, whole blood). The linear concentration ranges obtained for the molecular recognition and quantification of IDH1 and IDH2 were: IDH1 (1 × 10⁻⁵–1 × 10² ng mL⁻¹) and IDH2 (5 × 10⁻⁸ − 5 × 10² ng mL⁻¹). The limits of quantification obtained using the proposed microsensors were: 10 fg mL^–1 for IDH1 and 5 × 10⁻³ fg mL⁻¹ for IDH2. The highest sensitivities were obtained for the microsensor based on MWCNT. High recoveries versus enzyme-linked immunosorbent assay (ELISA) standard method were recorded for the assays of IDH1 and IDH2, all values being higher than 99.00%, with relative standard deviations (RSD) lower than 0.10%. Full article

(This article belongs to the Special Issue Nanomaterials in Miniaturized Separation and Sensing Devices, Apparatuses and Installations)

► Show Figures

Figure 1

23 pages, 9829 KiB

Open AccessEditor’s ChoiceArticle

Multimodal Contrast Agent Enabling pH Sensing Based on Organically Functionalized Gold Nanoshells with Mn-Zn Ferrite Cores

by Duong Thuy Bui, Radim Havelek, Karel Královec, Lenka Kubíčková, Jarmila Kuličková, Petr Matouš, Vít Herynek, Jaroslav Kupčík, Darina Muthná, Pavel Řezanka and Ondřej Kaman

Nanomaterials 2022, 12(3), 428; https://doi.org/10.3390/nano12030428 - 27 Jan 2022

Cited by 6 | Viewed by 3719

Abstract

Highly complex nanoparticles combining multimodal imaging with the sensing of physical properties in biological systems can considerably enhance biomedical research, but reports demonstrating the performance of a single nanosized probe in several imaging modalities and its sensing potential at the same time are [...] Read more.

Highly complex nanoparticles combining multimodal imaging with the sensing of physical properties in biological systems can considerably enhance biomedical research, but reports demonstrating the performance of a single nanosized probe in several imaging modalities and its sensing potential at the same time are rather scarce. Gold nanoshells with magnetic cores and complex organic functionalization may offer an efficient multimodal platform for magnetic resonance imaging (MRI), photoacoustic imaging (PAI), and fluorescence techniques combined with pH sensing by means of surface-enhanced Raman spectroscopy (SERS). In the present study, the synthesis of gold nanoshells with Mn-Zn ferrite cores is described, and their structure, composition, and fundamental properties are analyzed by powder X-ray diffraction, X-ray fluorescence spectroscopy, transmission electron microscopy, magnetic measurements, and UV-Vis spectroscopy. The gold surface is functionalized with four different model molecules, namely thioglycerol, meso-2,3-dimercaptosuccinate, 11-mercaptoundecanoate, and (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide, to analyze the effect of varying charge and surface chemistry on cells in vitro. After characterization by dynamic and electrophoretic light scattering measurements, it is found that the particles do not exhibit significant cytotoxic effects, irrespective of the surface functionalization. Finally, the gold nanoshells are functionalized with a combination of 4-mercaptobenzoic acid and 7-mercapto-4-methylcoumarin, which introduces a SERS active pH sensor and a covalently attached fluorescent tag at the same time. ¹H NMR relaxometry, fluorescence spectroscopy, and PAI demonstrate the multimodal potential of the suggested probe, including extraordinarily high transverse relaxivity, while the SERS study evidences a pH-dependent spectral response. Full article

(This article belongs to the Special Issue Recent Advances in Luminescent Nanocomposites for Sensing Applications)

► Show Figures

Figure 1

12 pages, 2139 KiB

Open AccessEditor’s ChoiceArticle

Combination of Polysaccharide Nanofibers Derived from Cellulose and Chitin Promotes the Adhesion, Migration and Proliferation of Mouse Fibroblast Cells

by Tomoka Noda, Mayumi Hatakeyama and Takuya Kitaoka

Nanomaterials 2022, 12(3), 402; https://doi.org/10.3390/nano12030402 - 26 Jan 2022

Cited by 17 | Viewed by 3991

Abstract

Extracellular matrix (ECM) as a structural and biochemical scaffold to surrounding cells plays significant roles in cell adhesion, migration, proliferation and differentiation. Herein, we show the novel combination of TEMPO-oxidized cellulose nanofiber (TOCNF) and surface-N-deacetylated chitin nanofiber (SDCtNF), respectively, having carboxylate [...] Read more.

Extracellular matrix (ECM) as a structural and biochemical scaffold to surrounding cells plays significant roles in cell adhesion, migration, proliferation and differentiation. Herein, we show the novel combination of TEMPO-oxidized cellulose nanofiber (TOCNF) and surface-N-deacetylated chitin nanofiber (SDCtNF), respectively, having carboxylate and amine groups on each crystalline surface, for mouse fibroblast cell culture. The TOCNF/SDCtNF composite scaffolds demonstrated characteristic cellular behavior, strongly depending on the molar ratios of carboxylates and amines of polysaccharide NFs. Pure TOCNF substrate exhibited good cell attachment, although intact carboxylate-free CNF made no contribution to cell adhesion. By contrast, pure SDCtNF induced crucial cell aggregation to form spheroids; nevertheless, the combination of TOCNF and SDCtNF enhanced cell attachment and subsequent proliferation. Molecular blend of carboxymethylcellulose and acid-soluble chitosan made nearly no contribution to cell culture behavior. The wound healing assay revealed that the polysaccharide combination markedly promoted skin repair for wound healing. Both of TOCNF and SDCtNF possessed rigid nanofiber nanoarchitectures with native crystalline forms and regularly-repeated functional groups, of which such structural characteristics would provide a potential for developing cell culture scaffolds having ECM functions, possibly promoting good cellular adhesion, migration and growth in the designated cellular microenvironments. Full article

(This article belongs to the Special Issue Emerging Functions of Nano-Organized Polysaccharides)

► Show Figures

Figure 1

15 pages, 2393 KiB

Open AccessEditor’s ChoiceArticle

A Fluorescent Nanosensor for Silver (Ag⁺) and Mercury (Hg²⁺) Ions Using Eu (III)-Doped Carbon Dots

by Cátia Correia, José Martinho and Ermelinda Maçôas

Nanomaterials 2022, 12(3), 385; https://doi.org/10.3390/nano12030385 - 25 Jan 2022

Cited by 23 | Viewed by 3990

Abstract

Carbon dots doped with Eu³⁺ ions (Eu-Cdots) were prepared by a hydrothermal treatment, using citric acid and urea as precursors and Eu (NO₃)₃ as a europium source. The Eu³⁺ ions are strongly coordinated with the carboxylate groups at [...] Read more.

Carbon dots doped with Eu³⁺ ions (Eu-Cdots) were prepared by a hydrothermal treatment, using citric acid and urea as precursors and Eu (NO₃)₃ as a europium source. The Eu³⁺ ions are strongly coordinated with the carboxylate groups at the surface of the Cdots and incorporated within the nanographene network in the carbon core. Vibrational spectroscopy provides evidence of such interaction with identification of bands assigned to the stretching of the Eu-O bond. Eu³⁺ doped Cdots have larger diameters then undoped Cdots, but they are divided into smaller domains of sp² carbon. The UV-vis excitation spectrum provides evidence of energy transfer from the Cdots to the Eu³⁺. The luminescence spectrum shows the characteristic sharp peaks of Eu³⁺ in the red part of the visible spectrum and a broad emission of Cdots centered at 450 nm. The luminescence of the Cdots is strongly quenched by Hg²⁺ and Ag⁺, but not by other cations. The quenching mechanism differs significantly depending on the nature of the ion. Both the blue emission of Cdots and the red emission of Eu³⁺ are quenched in the presence of Hg²⁺ while only the emission of the Cdots is affected by the presence of Ag⁺. A ratiometric sensor can be built using the ratio of luminescence intensities of the Cdots to the Eu³⁺ peaks. Full article

(This article belongs to the Special Issue Optically Responsive Nanomaterials)

► Show Figures

Graphical abstract

8 pages, 1214 KiB

Open AccessEditor’s ChoiceArticle

Line Tension and Drop Size Dependence of Contact Angle at the Nanoscale

by Waldemar Klauser, Fabian T. von Kleist-Retzow and Sergej Fatikow

Nanomaterials 2022, 12(3), 369; https://doi.org/10.3390/nano12030369 - 24 Jan 2022

Cited by 13 | Viewed by 3664

Abstract

Despite considerable research efforts, the influence of contact line tension during wetting at the nanoscale and its experimental determination remain challenging tasks. So far, molecular dynamics simulations and atomic force microscope measurements have contributed to the understanding of these phenomena. However, a direct [...] Read more.

Despite considerable research efforts, the influence of contact line tension during wetting at the nanoscale and its experimental determination remain challenging tasks. So far, molecular dynamics simulations and atomic force microscope measurements have contributed to the understanding of these phenomena. However, a direct measurement of the size dependence of the contact angle and the magnitude of the apparent line tension has not been realized so far. Here, we show that the contact angle is indeed dependent on the drop size for small drop diameters and determine the magnitude of the apparent line tension via liquid-metal based measurements of advancing and receding contact angle inside a scanning electron microscope. For this purpose, a robotic setup inside an electron microscope chamber and oxide-free Galinstan droplets—produced via an electromigration-based and focused ion beam irradiation-assisted process—are employed. Using the first-order correction of Young’s equation, we find an apparent line tension value of 4.02 × 10⁻⁷ J/m for Galinstan© on stainless steel. Full article

(This article belongs to the Special Issue Nano-Manipulation)

► Show Figures

Figure 1

18 pages, 4629 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Unprecedented Mechanochemical Synthesis and Heterogenization of a C-Scorpionate Au(III) Catalyst for Microwave-Assisted Biomass Valorization

by Inês A. S. Matias, Pablo G. Selfa, Ana M. Ferraria, Ana M. Botelho do Rego, Maximilian N. Kopylovich, Ana P. C. Ribeiro and Luísa M. D. R. S. Martins

Nanomaterials 2022, 12(3), 362; https://doi.org/10.3390/nano12030362 - 23 Jan 2022

Cited by 1 | Viewed by 3309

Abstract

The transformation of biomass, a carbon resource presenting a huge potential to produce valuable chemicals, requires the search for sustainable catalytic routes. This work proposes the microwave-assisted oxidation of biomass -derived substrates, such as glycerol and the furfural derivatives 5-(hydroxymethyl)furfural (HMF) and 5-hydroxymethyl-2-furancarboxylic [...] Read more.

The transformation of biomass, a carbon resource presenting a huge potential to produce valuable chemicals, requires the search for sustainable catalytic routes. This work proposes the microwave-assisted oxidation of biomass -derived substrates, such as glycerol and the furfural derivatives 5-(hydroxymethyl)furfural (HMF) and 5-hydroxymethyl-2-furancarboxylic acid (HFCA), using the C-scorpionate dichloro-gold(III) complex [AuCl₂(κ²-Tpm)]Cl (Tpm = HCpz₃; pz = pyrazol-1-yl) as a catalyst, as prepared and supported on graphene, in solvent-free conditions. The unprecedented application of a mechanochemical procedure (in a planetary ball mill, in solid state) to synthesize a C-scorpionate complex, the [AuCl₂(κ²-Tpm)]Cl, is disclosed. The immobilization of [AuCl₂(κ²-Tpm)]Cl on graphene was performed using different methods, including some (e.g., microwave irradiation and liquid assisted grinding) for the first time. The structural properties and the performance of the prepared catalytic materials are presented and discussed. Full article

(This article belongs to the Special Issue Nanoporous Carbon: Synthesis, Characterization, and Applications)

► Show Figures

Figure 1

14 pages, 4853 KiB

Open AccessEditor’s ChoiceArticle

Flexible and Effective Preparation of Magnetic Nanoclusters via One-Step Flow Synthesis

by Lin Zhou, Lu Ye and Yangcheng Lu

Nanomaterials 2022, 12(3), 350; https://doi.org/10.3390/nano12030350 - 22 Jan 2022

Cited by 9 | Viewed by 2343

Abstract

Fe₃O₄ nanoclusters have attractive applications in various areas, due to their outstanding superparamagnetism. In this work, we realized a one-step flow synthesis of Fe₃O₄ nanoclusters, within minutes, through the sequential and quantitative introduction of reactants and modifier [...] Read more.

Fe₃O₄ nanoclusters have attractive applications in various areas, due to their outstanding superparamagnetism. In this work, we realized a one-step flow synthesis of Fe₃O₄ nanoclusters, within minutes, through the sequential and quantitative introduction of reactants and modifier in a microflow system. The enhanced micromixing performance enabled a prompt and uniform supply of the modifier oleic acid (OA) for both nanoparticle modification and nanocluster stabilization to avoid uncontrolled modified nanoparticles aggregation. The size of the nanoclusters could be flexibly tailored in the range of 50–100 nm by adjusting the amount of OA, the pH, and the temperature. This rapid method proved the possibility of large-scale and stable production of magnetic nanoclusters and provided convenience for their applications in broad fields. Full article

(This article belongs to the Special Issue Nanomaterials Synthesis and Processing in Liquid Phase)

► Show Figures

Graphical abstract

14 pages, 5180 KiB

Open AccessEditor’s ChoiceArticle

Highly Efficient Photothermal Reduction of CO₂ on Pd₂Cu Dispersed TiO₂ Photocatalyst and Operando DRIFT Spectroscopic Analysis of Reactive Intermediates

by Munirathinam Elavarasan, Willie Yang, Sethupathi Velmurugan, Jyy-Ning Chen, Thomas C.-K. Yang and Toshiyuki Yokoi

Nanomaterials 2022, 12(3), 332; https://doi.org/10.3390/nano12030332 - 21 Jan 2022

Cited by 13 | Viewed by 3679

Abstract

The photocatalytic conversion of CO₂ to fuels using solar energy presents meaningful potential in the mitigation of global warming, solar energy conversion, and fuel production. Photothermal catalysis is one promising approach to convert chemically inert CO₂ into value-added chemicals. Herein, we [...] Read more.

The photocatalytic conversion of CO₂ to fuels using solar energy presents meaningful potential in the mitigation of global warming, solar energy conversion, and fuel production. Photothermal catalysis is one promising approach to convert chemically inert CO₂ into value-added chemicals. Herein, we report the selective hydrogenation of CO₂ to ethanol by Pd₂Cu alloy dispersed TiO₂ (P25) photocatalyst. Under UV-Vis irradiation, the Pd₂Cu/P25 showed an efficient CO₂ reduction photothermally at 150 °C with an ethanol production rate of 4.1 mmol g⁻¹ h⁻¹. Operando diffuse reflectance infrared Fourier transform (DRIFT) absorption studies were used to trace the reactive intermediates involved in CO₂ hydrogenation in detail. Overall, the Cu provides the active sites for CO₂ adsorption and Pd involves the oxidation of H₂ molecule generated from P25 and C–C bond formation. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

► Show Figures

Figure 1

11 pages, 2045 KiB

Open AccessEditor’s ChoiceArticle

Superfluorescence of Sub-Band States in C-Plane In_0.1Ga_0.9N/GaN Multiple-QWs

by Cairong Ding, Zesheng Lv, Xueran Zeng and Baijun Zhang

Nanomaterials 2022, 12(3), 327; https://doi.org/10.3390/nano12030327 - 20 Jan 2022

Cited by 1 | Viewed by 2185

Abstract

Superfluorescence is a collective emission from quantum coherent emitters due to quantum fluctuations. This is characterized by the existence of the delay time (

τ_{D})

for the emitters coupling and phase-synchronizing to each other spontaneously. Here we report the observation of [...] Read more.

Superfluorescence is a collective emission from quantum coherent emitters due to quantum fluctuations. This is characterized by the existence of the delay time (

τ_{D})

for the emitters coupling and phase-synchronizing to each other spontaneously. Here we report the observation of superfluorescence in c-plane In_0.1Ga_0.9N/GaN multiple-quantum wells by time-integrated and time-resolved photoluminescence spectroscopy under higher excitation fluences of the 267 nm laser and at room temperature, showing a characteristic

τ_{D}

from 79 ps to 62 ps and the ultrafast radiative decay (7.5 ps) after a burst of photons. Time-resolved traces present a small quantum oscillation from coupled In_0.1Ga_0.9N/GaN multiple-quantum wells. The superfluorescence is attributed to the radiative recombination of coherent emitters distributing on strongly localized subband states, E_e₁→E_hh₁ or E_e₁→E_lh₁ in 3nm width multiple-quantum wells. Our work paves the way for deepening the understanding of the emission mechanism in the In_0.1Ga_0.9N/GaN quantum well at a higher injected carrier density. Full article

(This article belongs to the Special Issue Advanced Nanocomposites for Photonics and Optoelectronics and Mechanics)

► Show Figures

Figure 1

14 pages, 22471 KiB

Open AccessEditor’s ChoiceArticle

Boosted Cross-Linking and Characterization of High-Performing Self-Assembling Peptides

by Maria Gessica Ciulla, Raffaele Pugliese and Fabrizio Gelain

Nanomaterials 2022, 12(3), 320; https://doi.org/10.3390/nano12030320 - 19 Jan 2022

Cited by 10 | Viewed by 3084

Abstract

Tissue engineering (TE) strategies require the design and characterization of novel biomaterials capable of mimicking the physiological microenvironments of the tissues to be regenerated. As such, implantable materials should be biomimetic, nanostructured and with mechanical properties approximating those of the target organ/tissue. Self-assembling [...] Read more.

Tissue engineering (TE) strategies require the design and characterization of novel biomaterials capable of mimicking the physiological microenvironments of the tissues to be regenerated. As such, implantable materials should be biomimetic, nanostructured and with mechanical properties approximating those of the target organ/tissue. Self-assembling peptides (SAPs) are biomimetic nanomaterials that can be readily synthesized and customized to match the requirements of some TE applications, but the weak interactions involved in the self-assembling phenomenon make them soft hydrogels unsuited for the regeneration of medium-to-hard tissues. In this work, we moved significant steps forward in the field of chemical cross-linked SAPs towards the goal of stiff peptidic materials suited for the regeneration of several tissues. Novel SAPs were designed and characterized to boost the 4-(N-Maleimidomethyl) cyclohexane-1-carboxylic acid 3-sulpho-N-hydroxysuccinimide ester (Sulfo-SMCC) mediated cross-linking reaction, where they reached G′ values of ~500 kPa. An additional orthogonal cross-linking was also effective and allowed to top remarkable G′ values of 840 kPa. We demonstrated that cross-linking fastened the pre-existing self-aggregated nanostructures, and at the same time, a strong presence of ß-structures is necessary for an effective cross-linking of (LKLK)₃-based SAPs. Combining strong SAP design and orthogonal cross-linking reactions, we brought SAP stiffness closer to the MPa threshold, and as such, we opened the door of the regeneration of skin, muscle and lung to biomimetic SAP technology. Full article

(This article belongs to the Section Biology and Medicines)

► Show Figures

Graphical abstract

19 pages, 6455 KiB

Open AccessEditor’s ChoiceArticle

Inverse Identification of Single-Crystal Plasticity Parameters of HCP Zinc from Nanoindentation Curves and Residual Topographies

by Pham T. N. Nguyen, Fazilay Abbès, Jean-Sébastien Lecomte, Christophe Schuman and Boussad Abbès

Nanomaterials 2022, 12(3), 300; https://doi.org/10.3390/nano12030300 - 18 Jan 2022

Cited by 9 | Viewed by 2768

Abstract

This paper investigates the orientation-dependent characteristics of pure zinc under localized loading using nanoindentation experiments and crystal plasticity finite element (CPFEM) simulations. Nanoindentation experiments on different grain orientations exhibited distinct load–depth responses. Atomic force microscopy revealed two-fold unsymmetrical material pile-up patterns. Obtaining crystal [...] Read more.

This paper investigates the orientation-dependent characteristics of pure zinc under localized loading using nanoindentation experiments and crystal plasticity finite element (CPFEM) simulations. Nanoindentation experiments on different grain orientations exhibited distinct load–depth responses. Atomic force microscopy revealed two-fold unsymmetrical material pile-up patterns. Obtaining crystal plasticity model parameters usually requires time-consuming micromechanical tests. Inverse analysis using experimental and simulated loading–unloading nanoindentation curves of individual grains is commonly used, however the solution to the inverse identification problem is not necessarily unique. In this study, an approach is presented allowing the identification of CPFEM constitutive parameters from nanoindentation curves and residual topographies. The proposed approach combines the response surface methodology together with a genetic algorithm to determine an optimal set of parameters. The CPFEM simulations corroborate with measured nanoindentation curves and residual profiles and reveal the evolution of deformation activity underneath the indenter. Full article

(This article belongs to the Special Issue Computational Study of Nanomaterials)

► Show Figures

Figure 1

14 pages, 4490 KiB

Open AccessEditor’s ChoiceArticle

Sea Urchin-like Si@MnO₂@rGO as Anodes for High-Performance Lithium-Ion Batteries

by Jiajun Liu, Meng Wang, Qi Wang, Xishan Zhao, Yutong Song, Tianming Zhao and Jing Sun

Nanomaterials 2022, 12(2), 285; https://doi.org/10.3390/nano12020285 - 17 Jan 2022

Cited by 16 | Viewed by 3835

Abstract

Si is a promising material for applications as a high-capacity anode material of lithium-ion batteries. However, volume expansion, poor electrical conductivity, and a short cycle life during the charging/discharging process limit the commercial use. In this paper, new ternary composites of sea urchin-like [...] Read more.

Si is a promising material for applications as a high-capacity anode material of lithium-ion batteries. However, volume expansion, poor electrical conductivity, and a short cycle life during the charging/discharging process limit the commercial use. In this paper, new ternary composites of sea urchin-like Si@MnO₂@reduced graphene oxide (rGO) prepared by a simple, low-cost chemical method are presented. These can effectively reduce the volume change of Si, extend the cycle life, and increase the lithium-ion battery capacity due to the dual protection of MnO₂ and rGO. The sea urchin-like Si@MnO₂@rGO anode shows a discharge specific capacity of 1282.72 mAh g⁻¹ under a test current of 1 A g⁻¹ after 1000 cycles and excellent chemical performance at different current densities. Moreover, the volume expansion of sea urchin-like Si@MnO₂@rGO anode material is ~50% after 150 cycles, which is much less than the volume expansion of Si (300%). This anode material is economical and environmentally friendly and this work made efforts to develop efficient methods to store clean energy and achieve carbon neutrality. Full article

(This article belongs to the Special Issue Nanostructured Electrodes for High-Performance Supercapacitors and Batteries)

► Show Figures

Graphical abstract

17 pages, 1123 KiB

Open AccessEditor’s ChoiceReview

Nanodelivery Strategies for Skin Diseases with Barrier Impairment: Focusing on Ceramides and Glucocorticoids

by Cíntia Almeida, Patrícia Filipe, Catarina Rosado and Catarina Pereira-Leite

Nanomaterials 2022, 12(2), 275; https://doi.org/10.3390/nano12020275 - 15 Jan 2022

Cited by 12 | Viewed by 4463

Abstract

The human epidermis has a characteristic lipidic composition in the stratum corneum, where ceramides play a crucial role in the skin barrier homeostasis and in water-holding capacity. Several skin diseases, such as atopic dermatitis and psoriasis, exhibit a dysfunction in the lipid barrier [...] Read more.

The human epidermis has a characteristic lipidic composition in the stratum corneum, where ceramides play a crucial role in the skin barrier homeostasis and in water-holding capacity. Several skin diseases, such as atopic dermatitis and psoriasis, exhibit a dysfunction in the lipid barrier with altered ceramide levels and increased loss of transepidermal water. Glucocorticoids are normally employed in the therapeutical management of these pathologies. However, they have shown a poor safety profile and reduced treatment efficiency. The main objective of this review is to, within the framework of the limitations of the currently available therapeutical approaches, establish the relevance of nanocarriers as a safe and efficient delivery strategy for glucocorticoids and ceramides in the topical treatment of skin disorders with barrier impairment. Full article

(This article belongs to the Special Issue Delivery Systems Based on Innovative Nanomaterials)

► Show Figures

Figure 1

15 pages, 3756 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of POSS Type on the Space Environment Durability of Epoxy-POSS Nanocomposites

by Avraham I. Bram, Irina Gouzman, Asaf Bolker, Nurit Atar, Noam Eliaz and Ronen Verker

Nanomaterials 2022, 12(2), 257; https://doi.org/10.3390/nano12020257 - 14 Jan 2022

Cited by 4 | Viewed by 2649

Abstract

In order to use polymers at low Earth orbit (LEO) environment, they must be protected against atomic oxygen (AO) erosion. A promising protection strategy is to incorporate polyhedral oligomeric silsesquioxane (POSS) molecules into the polymer backbone. In this study, the space durability of [...] Read more.

In order to use polymers at low Earth orbit (LEO) environment, they must be protected against atomic oxygen (AO) erosion. A promising protection strategy is to incorporate polyhedral oligomeric silsesquioxane (POSS) molecules into the polymer backbone. In this study, the space durability of epoxy-POSS (EPOSS) nanocomposites was investigated. Two types of POSS molecules were incorporated separately—amine-based and epoxy-based. The outgassing properties of the EPOSS, in terms of total mass loss, collected volatile condensable material, and water vapor regain were measured as a function of POSS type and content. The AO durability was studied using a ground-based AO simulation system. Surface compositions of EPOSS were studied using high-resolution scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that with respect to the outgassing properties, only some of the EPOSS compositions were suitable for the ultrahigh vacuum space environment, and that the POSS type and content had a strong effect on their outgassing properties. Regardless of the POSS type being used, the AO durability improved significantly. This improvement is attributed to the formation of a self-passivated AO durable SiO₂ layer, and demonstrates the potential use of EPOSS as a qualified nanocomposite for space applications. Full article

(This article belongs to the Special Issue Nanomaterials for Potential Uses in Extraterrestrial Environments)

► Show Figures

Figure 1

15 pages, 9451 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Plasma Deposition of Carbon Nanomaterials Using Various Polymer Materials as a Carbon Atom Source

by Alenka Vesel, Rok Zaplotnik, Gregor Primc, Domen Paul and Miran Mozetič

Nanomaterials 2022, 12(2), 246; https://doi.org/10.3390/nano12020246 - 13 Jan 2022

Cited by 5 | Viewed by 1972

Abstract

Carbon nanowalls are promising materials for various electrochemical devices due to their chemical inertness, desirable electrical conductivity, and excellent surface-to-mass ratio. Standard techniques, often based on plasma-assisted deposition using gaseous precursors, enable the synthesis of top-quality carbon nanowalls, but require long deposition times [...] Read more.

Carbon nanowalls are promising materials for various electrochemical devices due to their chemical inertness, desirable electrical conductivity, and excellent surface-to-mass ratio. Standard techniques, often based on plasma-assisted deposition using gaseous precursors, enable the synthesis of top-quality carbon nanowalls, but require long deposition times which represents a serious obstacle for mass applications. Here, an alternative deposition technique is presented. The carbon nanowalls were synthesized on titanium substrates using various polymers as solid precursors. A solid precursor and the substrate were mounted into a low-pressure plasma reactor. Plasma was sustained by an inductively coupled radiofrequency discharge in the H-mode at the power of 500 W. Spontaneous growth of carbon nanomaterials was observed for a variety of polymer precursors. The best quality of carbon nanowalls was obtained using aliphatic polyolefins. The highest growth rate of a thin film of carbon nanowalls of about 200 nm/s was observed. The results were explained by different degradation mechanisms of polymers upon plasma treatment and the surface kinetics. Full article

(This article belongs to the Special Issue Conducting Polymer Nanocomposites Based on Carbon Nanomaterials (CNMs))

► Show Figures

Graphical abstract

9 pages, 1862 KiB

Open AccessEditor’s ChoiceArticle

Defect-Induced π-Magnetism into Non-Benzenoid Nanographenes

by Kalyan Biswas, Lin Yang, Ji Ma, Ana Sánchez-Grande, Qifan Chen, Koen Lauwaet, José M. Gallego, Rodolfo Miranda, David Écija, Pavel Jelínek, Xinliang Feng and José I. Urgel

Nanomaterials 2022, 12(2), 224; https://doi.org/10.3390/nano12020224 - 11 Jan 2022

Cited by 10 | Viewed by 4414

Abstract

The synthesis of nanographenes (NGs) with open-shell ground states have recently attained increasing attention in view of their interesting physicochemical properties and great prospects in manifold applications as suitable materials within the rising field of carbon-based magnetism. A potential route to induce magnetism [...] Read more.

The synthesis of nanographenes (NGs) with open-shell ground states have recently attained increasing attention in view of their interesting physicochemical properties and great prospects in manifold applications as suitable materials within the rising field of carbon-based magnetism. A potential route to induce magnetism in NGs is the introduction of structural defects, for instance non-benzenoid rings, in their honeycomb lattice. Here, we report the on-surface synthesis of three open-shell non-benzenoid NGs (A₁, A₂ and A₃) on the Au(111) surface. A₁ and A₂ contain two five- and one seven-membered rings within their benzenoid backbone, while A₃ incorporates one five-membered ring. Their structures and electronic properties have been investigated by means of scanning tunneling microscopy, noncontact atomic force microscopy and scanning tunneling spectroscopy complemented with theoretical calculations. Our results provide access to open-shell NGs with a combination of non-benzenoid topologies previously precluded by conventional synthetic procedures. Full article

(This article belongs to the Special Issue On-Surface Synthesis of Low-Dimensional Organic Nanostructures)

► Show Figures

Figure 1

26 pages, 63495 KiB

Open AccessEditor’s ChoiceArticle

Improving the Performance of BaMnO₃ Perovskite as Soot Oxidation Catalyst Using Carbon Black during Sol-Gel Synthesis

by Verónica Torregrosa-Rivero, María-Salvadora Sánchez-Adsuar and María-José Illán-Gómez

Nanomaterials 2022, 12(2), 219; https://doi.org/10.3390/nano12020219 - 10 Jan 2022

Cited by 10 | Viewed by 2902

Abstract

A series of BaMnO₃ solids (BM-CX) were prepared by a modified sol-gel method in which a carbon black (VULCAN XC-72R), and different calcination temperatures (600–850 °C) were used. The fresh and used catalysts were characterized by ICP-OES, XRD, XPS, FESEM, TEM, O [...] Read more.

A series of BaMnO₃ solids (BM-CX) were prepared by a modified sol-gel method in which a carbon black (VULCAN XC-72R), and different calcination temperatures (600–850 °C) were used. The fresh and used catalysts were characterized by ICP-OES, XRD, XPS, FESEM, TEM, O_2-TPD and H_2- TPR-. The characterization results indicate that the use of low calcination temperatures in the presence of carbon black allows decreasing the sintering effects and achieving some improvements regarding BM reference catalyst: (i) smaller average crystal and particles size, (ii) a slight increase in the BET surface area, (iii) a decrease in the macropores diameter range and, (iv) a lower temperature for the reduction of manganese. The hydrogen consumption confirms Mn(III) and Mn(IV) are presented in the samples, Mn(III) being the main oxidation state. The BM-CX catalysts series shows an improved catalytic performance regarding BM reference catalyst for oxidation processes (NO to NO₂ and NO₂-assisted soot oxidation), promoting higher stability and higher CO₂ selectivity. BM-C700 shows the best catalytic performance, i.e., the highest thermal stability and a high initial soot oxidation rate, which decreases the accumulation of soot during the soot oxidation and, consequently, minimizes the catalyst deactivation. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials Based on Perovskites)

► Show Figures

Figure 1

13 pages, 5387 KiB

Open AccessEditor’s ChoiceArticle

Simultaneous Extraction of the Grain Size, Single-Crystalline Grain Sheet Resistance, and Grain Boundary Resistivity of Polycrystalline Monolayer Graphene

by Honghwi Park, Junyeong Lee, Chang-Ju Lee, Jaewoon Kang, Jiyeong Yun, Hyowoong Noh, Minsu Park, Jonghyung Lee, Youngjin Park, Jonghoo Park, Muhan Choi, Sunghwan Lee and Hongsik Park

Nanomaterials 2022, 12(2), 206; https://doi.org/10.3390/nano12020206 - 9 Jan 2022

Cited by 7 | Viewed by 2957

Abstract

The electrical properties of polycrystalline graphene grown by chemical vapor deposition (CVD) are determined by grain-related parameters—average grain size, single-crystalline grain sheet resistance, and grain boundary (GB) resistivity. However, extracting these parameters still remains challenging because of the difficulty in observing graphene GBs [...] Read more.

The electrical properties of polycrystalline graphene grown by chemical vapor deposition (CVD) are determined by grain-related parameters—average grain size, single-crystalline grain sheet resistance, and grain boundary (GB) resistivity. However, extracting these parameters still remains challenging because of the difficulty in observing graphene GBs and decoupling the grain sheet resistance and GB resistivity. In this work, we developed an electrical characterization method that can extract the average grain size, single-crystalline grain sheet resistance, and GB resistivity simultaneously. We observed that the material property, graphene sheet resistance, could depend on the device dimension and developed an analytical resistance model based on the cumulative distribution function of the gamma distribution, explaining the effect of the GB density and distribution in the graphene channel. We applied this model to CVD-grown monolayer graphene by characterizing transmission-line model patterns and simultaneously extracted the average grain size (~5.95 μm), single-crystalline grain sheet resistance (~321 Ω/sq), and GB resistivity (~18.16 kΩ-μm) of the CVD-graphene layer. The extracted values agreed well with those obtained from scanning electron microscopy images of ultraviolet/ozone-treated GBs and the electrical characterization of graphene devices with sub-micrometer channel lengths. Full article

(This article belongs to the Special Issue Graphene for Electronics)

► Show Figures

Figure 1

18 pages, 2780 KiB

Open AccessEditor’s ChoiceArticle

Double-Layer Fatty Acid Nanoparticles as a Multiplatform for Diagnostics and Therapy

by María Salvador, José Luis Marqués-Fernández, José Carlos Martínez-García, Dino Fiorani, Paolo Arosio, Matteo Avolio, Francesca Brero, Florica Balanean, Andrea Guerrini, Claudio Sangregorio, Vlad Socoliuc, Ladislau Vekas, Davide Peddis and Montserrat Rivas

Nanomaterials 2022, 12(2), 205; https://doi.org/10.3390/nano12020205 - 8 Jan 2022

Cited by 14 | Viewed by 3132

Abstract

Today, public health is one of the most important challenges in society. Cancer is the leading cause of death, so early diagnosis and localized treatments that minimize side effects are a priority. Magnetic nanoparticles have shown great potential as magnetic resonance imaging contrast [...] Read more.

Today, public health is one of the most important challenges in society. Cancer is the leading cause of death, so early diagnosis and localized treatments that minimize side effects are a priority. Magnetic nanoparticles have shown great potential as magnetic resonance imaging contrast agents, detection tags for in vitro biosensing, and mediators of heating in magnetic hyperthermia. One of the critical characteristics of nanoparticles to adjust to the biomedical needs of each application is their polymeric coating. Fatty acid coatings are known to contribute to colloidal stability and good surface crystalline quality. While monolayer coatings make the particles hydrophobic, a fatty acid double-layer renders them hydrophilic, and therefore suitable for use in body fluids. In addition, they provide the particles with functional chemical groups that allow their bioconjugation. This work analyzes three types of self-assembled bilayer fatty acid coatings of superparamagnetic iron oxide nanoparticles: oleic, lauric, and myristic acids. We characterize the particles magnetically and structurally and study their potential for resonance imaging, magnetic hyperthermia, and labeling for biosensing in lateral flow immunoassays. We found that the myristic acid sample reported a large

r_{2}

relaxivity, superior to existing iron-based commercial agents. For magnetic hyperthermia, a significant specific absorption rate value was obtained for the oleic sample. Finally, the lauric acid sample showed promising results for nanolabeling. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Sensor Applications)

► Show Figures

Graphical abstract

11 pages, 6138 KiB

Open AccessEditor’s ChoiceArticle

Effect of the Dopant Configuration on the Electronic Transport Properties of Nitrogen-Doped Carbon Nanotubes

by Kim Eklund and Antti J. Karttunen

Nanomaterials 2022, 12(2), 199; https://doi.org/10.3390/nano12020199 - 7 Jan 2022

Cited by 9 | Viewed by 3220

Abstract

Nitrogen-doped carbon nanotubes (N-CNTs) show promise in several applications related to catalysis and electrochemistry. In particular, N-CNTs with a single nitrogen dopant in the unit cell have been extensively studied computationally, but the structure-property correlations between the relative positions of several nitrogen dopants [...] Read more.

Nitrogen-doped carbon nanotubes (N-CNTs) show promise in several applications related to catalysis and electrochemistry. In particular, N-CNTs with a single nitrogen dopant in the unit cell have been extensively studied computationally, but the structure-property correlations between the relative positions of several nitrogen dopants and the electronic transport properties of N-CNTs have not been systematically investigated with accurate hybrid density functional methods. We use hybrid density functional theory and semiclassical Boltzmann transport theory to systematically investigate the effect of different substitutional nitrogen doping configurations on the electrical conductivity of N-CNTs. Our results indicate significant variation in the electrical conductivity and the relative energies of the different dopant configurations. The findings can be utilized in the optimization of electrical transport properties of N-CNTs. Full article

(This article belongs to the Special Issue Theoretical Calculation and Molecular Modeling of Nanomaterials)

► Show Figures

Figure 1

13 pages, 8345 KiB

Open AccessEditor’s ChoiceArticle

Ethanol Solvothermal Treatment on Graphitic Carbon Nitride Materials for Enhancing Photocatalytic Hydrogen Evolution Performance

by Phuong Anh Nguyen, Thi Kim Anh Nguyen, Duc Quang Dao and Eun Woo Shin

Nanomaterials 2022, 12(2), 179; https://doi.org/10.3390/nano12020179 - 6 Jan 2022

Cited by 20 | Viewed by 3451

Abstract

Recently, Pt-loaded graphic carbon nitride (g-C₃N₄) materials have attracted great attention as a photocatalyst for hydrogen evolution from water. The simple surface modification of g-C₃N₄ by hydrothermal methods improves photocatalytic performance. In this study, ethanol is [...] Read more.

Recently, Pt-loaded graphic carbon nitride (g-C₃N₄) materials have attracted great attention as a photocatalyst for hydrogen evolution from water. The simple surface modification of g-C₃N₄ by hydrothermal methods improves photocatalytic performance. In this study, ethanol is used as a solvothermal solvent to modify the surface properties of g-C₃N₄ for the first time. The g-C₃N₄ is thermally treated in ethanol at different temperatures (T = 140 °C, 160 °C, 180 °C, and 220 °C), and the Pt co-catalyst is subsequently deposited on the g-C₃N₄ via a photodeposition method. Elemental analysis and XPS O 1s data confirm that the ethanol solvothermal treatment increased the contents of the oxygen-containing functional groups on the g-C₃N₄ and were proportional to the treatment temperatures. However, the XPS Pt 4f data show that the Pt²⁺/Pt⁰ value for the Pt/g-C₃N₄ treated at ethanol solvothermal temperature of 160 °C (Pt/CN-160) is the highest at 7.03, implying the highest hydrogen production rate of Pt/CN-160 is at 492.3 μmol g⁻¹ h⁻¹ because the PtO phase is favorable for the water adsorption and hydrogen desorption in the hydrogen evolution process. In addition, the electrochemical impedance spectroscopy data and the photoluminescence spectra emission peak intensify reflect that the Pt/CN-160 had a more efficient charge separation process that also enhanced the photocatalytic activity. Full article

(This article belongs to the Special Issue Performance of Nanocomposite for Optoelectronic Applications)

► Show Figures

Figure 1

14 pages, 15216 KiB

Open AccessEditor’s ChoiceArticle

Facile Synthesis of Silver Nanoparticles and Preparation of Conductive Ink

by Gui Bing Hong, Yi Hua Luo, Kai Jen Chuang, Hsiu Yueh Cheng, Kai Chau Chang and Chih Ming Ma

Nanomaterials 2022, 12(1), 171; https://doi.org/10.3390/nano12010171 - 5 Jan 2022

Cited by 18 | Viewed by 4095

Abstract

In the scientific industry, sustainable nanotechnology has attracted great attention and has been successful in facilitating solutions to challenges presented in various fields. For the present work, silver nanoparticles (AgNPs) were prepared using a chemical reduction synthesis method. Then, a low-temperature sintering process [...] Read more.

In the scientific industry, sustainable nanotechnology has attracted great attention and has been successful in facilitating solutions to challenges presented in various fields. For the present work, silver nanoparticles (AgNPs) were prepared using a chemical reduction synthesis method. Then, a low-temperature sintering process was deployed to obtain an Ag-conductive ink preparation which could be applied to a flexible substrate. The size and shape of the AgNPs were characterized by ultraviolet–visible spectrophotometry (UV-Vis) and transmission electron microscopy (TEM). The experiments indicated that the size and agglomeration of the AgNPs could be well controlled by varying the reaction time, reaction temperature, and pH value. The rate of nanoparticle generation was the highest when the reaction temperature was 100 °C within the 40 min reaction time, achieving the most satisfactorily dispersed nanoparticles and nanoballs with an average size of 60.25 nm at a pH value of 8. Moreover, the electrical resistivity of the obtained Ag-conductive ink is controllable, under the optimal sintering temperature and time (85 °C for 5 min), leading to an optimal electrical resistivity of 9.9 × 10⁻⁶ Ω cm. The results obtained in this study, considering AgNPs and Ag-conductive ink, may also be extended to other metals in future research. Full article

(This article belongs to the Special Issue Interfacial Phenomena and Nanoparticle Engineering—Spotlight on Early Career Investigators 2021)

► Show Figures

Figure 1

15 pages, 2188 KiB

Open AccessEditor’s ChoiceArticle

Artificial Neural Network Modelling for Optimizing the Optical Parameters of Plasmonic Paired Nanostructures

by Sneha Verma, Sunny Chugh, Souvik Ghosh and B. M. Azizur Rahman

Nanomaterials 2022, 12(1), 170; https://doi.org/10.3390/nano12010170 - 4 Jan 2022

Cited by 12 | Viewed by 3496

Abstract

The Artificial Neural Network (ANN) has become an attractive approach in Machine Learning (ML) to analyze a complex data-driven problem. Due to its time efficient findings, it has became popular in many scientific fields such as physics, optics, and material science. This paper [...] Read more.

The Artificial Neural Network (ANN) has become an attractive approach in Machine Learning (ML) to analyze a complex data-driven problem. Due to its time efficient findings, it has became popular in many scientific fields such as physics, optics, and material science. This paper presents a new approach to design and optimize the electromagnetic plasmonic nanostructures using a computationally efficient method based on the ANN. In this work, the nanostructures have been simulated by using a Finite Element Method (FEM), then Artificial Intelligence (AI) is used for making predictions of associated sensitivity (S), Full Width Half Maximum (FWHM), Figure of Merit (FOM), and Plasmonic Wavelength (PW) for different paired nanostructures. At first, the computational model is developed by using a Finite Element Method (FEM) to prepare the dataset. The input parameters were considered as the Major axis, a, the Minor axis, b, and the separation gap, g, which have been used to calculate the corresponding sensitivity (nm/RIU), FWHM (nm), FOM, and plasmonic wavelength (nm) to prepare the dataset. Secondly, the neural network has been designed where the number of hidden layers and neurons were optimized as part of a comprehensive analysis to improve the efficiency of ML model. After successfully optimizing the neural network, this model is used to make predictions for specific inputs and its corresponding outputs. This article also compares the error between the predicted and simulated results. This approach outperforms the direct numerical simulation methods for predicting output for various input device parameters. Full article

(This article belongs to the Special Issue Nanosensors)

► Show Figures

Graphical abstract

24 pages, 2103 KiB

Open AccessEditor’s ChoiceReview

The Impact of the Surface Modification on Tin-Doped Indium Oxide Nanocomposite Properties

by Arash Fattahi, Peyman Koohsari, Muhammad Shadman Lakmehsari and Khashayar Ghandi

Nanomaterials 2022, 12(1), 155; https://doi.org/10.3390/nano12010155 - 3 Jan 2022

Cited by 7 | Viewed by 4127

Abstract

This review provides an analysis of the theoretical methods to study the effects of surface modification on structural properties of nanostructured indium tin oxide (ITO), mainly by organic compounds. The computational data are compared with experimental data such as X-ray diffraction (XRD), atomic [...] Read more.

This review provides an analysis of the theoretical methods to study the effects of surface modification on structural properties of nanostructured indium tin oxide (ITO), mainly by organic compounds. The computational data are compared with experimental data such as X-ray diffraction (XRD), atomic force microscopy (AFM) and energy-dispersive X-ray spectroscopy (EDS) data with the focus on optoelectronic and electrocatalytic properties of the surface to investigate potential relations of these properties and applications of ITO in fields such as biosensing and electronic device fabrication. Our analysis shows that the change in optoelectronic properties of the surface is mainly due to functionalizing the surface with organic molecules and that the electrocatalytic properties vary as a function of size. Full article

(This article belongs to the Special Issue Advances in Nanostructured Semiconductors and Heterojunctions)

► Show Figures

Graphical abstract

15 pages, 3351 KiB

Open AccessEditor’s ChoiceArticle

Tailoring the Nonlinear Optical Response of Some Graphene Derivatives by Ultraviolet (UV) Irradiation

by Aristeidis Stathis, Zoi Bouza, Ioannis Papadakis and Stelios Couris

Nanomaterials 2022, 12(1), 152; https://doi.org/10.3390/nano12010152 - 1 Jan 2022

Cited by 7 | Viewed by 3195

Abstract

In the present work the impact of in situ photoreduction, by means of ultraviolet (UV) irradiation, on the nonlinear optical response (NLO) of some graphene oxide (GO), fluorographene (GF), hydrogenated fluorographene (GFH) and graphene (G) dispersions is studied. In situ UV photoreduction allowed [...] Read more.

In the present work the impact of in situ photoreduction, by means of ultraviolet (UV) irradiation, on the nonlinear optical response (NLO) of some graphene oxide (GO), fluorographene (GF), hydrogenated fluorographene (GFH) and graphene (G) dispersions is studied. In situ UV photoreduction allowed for the extended modification of the degree of functionalization (i.e., oxidization, fluorination and hydrogenation), leading to the effective tuning of the corresponding sp²/sp³ hybridization ratios. The nonlinear optical properties of the studied samples prior to and after UV irradiation were determined by means of the Z-scan technique using visible (532 nm), 4 ns laser excitation, and were found to change significantly. More specifically, while GO’s nonlinear optical response increases with irradiation time, GF and GFH present a monotonic decrease. The graphene dispersions’ nonlinear optical response remains unaffected after prolonged UV irradiation for more than an hour. The present findings demonstrate that UV photoreduction can be an effective and simple strategy for tuning the nonlinear optical response of these graphene derivatives in a controllable way, resulting in derivatives with custom-made responses, thus more suitable for different photonic and optoelectronic applications. Full article

(This article belongs to the Special Issue Nonlinear Optical Properties and Applications of 2D Carbon-Based Nanomaterials)

► Show Figures

Figure 1

12 pages, 31423 KiB

Open AccessEditor’s ChoiceArticle

Solution-Processed Smooth Copper Thiocyanate Layer with Improved Hole Injection Ability for the Fabrication of Quantum Dot Light-Emitting Diodes

by Ming-Ru Wen, Sheng-Hsiung Yang and Wei-Sheng Chen

Nanomaterials 2022, 12(1), 154; https://doi.org/10.3390/nano12010154 - 1 Jan 2022

Cited by 2 | Viewed by 3156

Abstract

Copper thiocyanate (CuSCN) has been gradually utilized as the hole injection layer (HIL) within optoelectronic devices, owing to its high transparency in the visible range, moderate hole mobility, and desirable environmental stability. In this research, we demonstrate quantum dot light-emitting diodes (QLEDs) with [...] Read more.

Copper thiocyanate (CuSCN) has been gradually utilized as the hole injection layer (HIL) within optoelectronic devices, owing to its high transparency in the visible range, moderate hole mobility, and desirable environmental stability. In this research, we demonstrate quantum dot light-emitting diodes (QLEDs) with high brightness and current efficiency by doping 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) in CuSCN as the HIL. The experimental results indicated a smoother surface of CuSCN upon F4TCNQ doping. The augmentation in hole mobility of CuSCN and carrier injection to reach balanced charge transport in QLEDs were confirmed. A maximum brightness of 169,230 cd m⁻² and a current efficiency of 35.1 cd A⁻¹ from the optimized device were received by adding 0.02 wt% of F4TCNQ in CuSCN, revealing promising use in light-emitting applications. Full article

(This article belongs to the Special Issue Cutting‐Edge Nanomaterials for Electronics in Asia: Synthesis, Properties, and Applications)

► Show Figures

Figure 1

12 pages, 3291 KiB

Open AccessEditor’s ChoiceArticle

Broadband Optical Constants and Nonlinear Properties of SnS₂ and SnSe₂

by Georgy A. Ermolaev, Dmitry I. Yakubovsky, Marwa A. El-Sayed, Mikhail K. Tatmyshevskiy, Arslan B. Mazitov, Anna A. Popkova, Ilya M. Antropov, Vladimir O. Bessonov, Aleksandr S. Slavich, Gleb I. Tselikov, Ivan A. Kruglov, Sergey M. Novikov, Andrey A. Vyshnevyy, Andrey A. Fedyanin, Aleksey V. Arsenin and Valentyn S. Volkov

Nanomaterials 2022, 12(1), 141; https://doi.org/10.3390/nano12010141 - 31 Dec 2021

Cited by 24 | Viewed by 4853

Abstract

SnS₂ and SnSe₂ have recently been shown to have a wide range of applications in photonic and optoelectronic devices. However, because of incomplete knowledge about their optical characteristics, the use of SnS₂ and SnSe₂ in optical engineering remains challenging. [...] Read more.

SnS₂ and SnSe₂ have recently been shown to have a wide range of applications in photonic and optoelectronic devices. However, because of incomplete knowledge about their optical characteristics, the use of SnS₂ and SnSe₂ in optical engineering remains challenging. Here, we addressed this problem by establishing SnS₂ and SnSe₂ linear and nonlinear optical properties in the broad (300–3300 nm) spectral range. Coupled with the first-principle calculations, our experimental study unveiled the full dielectric tensor of SnS₂ and SnSe₂. Furthermore, we established that SnS₂ is a promising material for visible high refractive index nanophotonics. Meanwhile, SnSe₂ demonstrates a stronger nonlinear response compared with SnS₂. Our results create a solid ground for current and next-generation SnS₂- and SnSe₂-based devices. Full article

► Show Figures

Figure 1

28 pages, 13003 KiB

Open AccessEditor’s ChoiceReview

Efficient and Stable Perovskite Solar Cells Based on Inorganic Hole Transport Materials

by Helen Hejin Park

Nanomaterials 2022, 12(1), 112; https://doi.org/10.3390/nano12010112 - 30 Dec 2021

Cited by 29 | Viewed by 5971

Abstract

Although power conversion efficiencies of organic-inorganic lead halide perovskite solar cells (PSCs) are approaching those of single-crystal silicon solar cells, the working device stability due to internal and external factors, such as light, temperature, and moisture, is still a key issue to address. [...] Read more.

Although power conversion efficiencies of organic-inorganic lead halide perovskite solar cells (PSCs) are approaching those of single-crystal silicon solar cells, the working device stability due to internal and external factors, such as light, temperature, and moisture, is still a key issue to address. The current world-record efficiency of PSCs is based on organic hole transport materials, which are usually susceptible to degradation from heat and diffusion of dopants. A simple solution would be to replace the generally used organic hole transport layers (HTLs) with a more stable inorganic material. This review article summarizes recent contributions of inorganic hole transport materials to PSC development, focusing on aspects of device performance and long-term stability. Future research directions of inorganic HTLs in the progress of PSC research and challenges still remaining will also be discussed. Full article

(This article belongs to the Special Issue Applications of Metal Halide Perovskites in Optoelectronic Devices)

► Show Figures

Figure 1

17 pages, 2668 KiB

Open AccessEditor’s ChoiceArticle

Rod–Coil Block Copolymer: Fullerene Blend Water-Processable Nanoparticles: How Molecular Structure Addresses Morphology and Efficiency in NP-OPVs

by Anna Maria Ferretti, Marianna Diterlizzi, William Porzio, Umberto Giovanella, Lucia Ganzer, Tersilla Virgili, Varun Vohra, Eduardo Arias, Ivana Moggio, Guido Scavia, Silvia Destri and Stefania Zappia

Nanomaterials 2022, 12(1), 84; https://doi.org/10.3390/nano12010084 - 29 Dec 2021

Cited by 4 | Viewed by 2308

Abstract

The use of water-processable nanoparticles (WPNPs) is an emerging strategy for the processing of organic semiconducting materials into aqueous medium, dramatically reducing the use of chlorinated solvents and enabling the control of the nanomorphology in OPV active layers. We studied amphiphilic rod-coil block [...] Read more.

The use of water-processable nanoparticles (WPNPs) is an emerging strategy for the processing of organic semiconducting materials into aqueous medium, dramatically reducing the use of chlorinated solvents and enabling the control of the nanomorphology in OPV active layers. We studied amphiphilic rod-coil block copolymers (BCPs) with a different chemical structure and length of the hydrophilic coil blocks. Using the BCPs blended with a fullerene acceptor material, we fabricated NP-OPV devices with a sustainable approach. The goal of this work is to clarify how the morphology of the nanodomains of the two active materials is addressed by the hydrophilic coil molecular structures, and in turn how the design of the materials affects the device performances. Exploiting a peculiar application of TEM, EFTEM microscopy on WPNPs, with the contribution of AFM and spectroscopic techniques, we correlate the coil structure with the device performances, demonstrating the pivotal influence of the chemical design over material properties. BCP5, bearing a coil block of five repeating units of 4-vinilpyridine (4VP), leads to working devices with efficiency comparable to the solution-processed ones for the multiple PCBM-rich cores morphology displayed by the blend WPNPs. Otherwise, BCP2 and BCP15, with 2 and 15 repeating units of 4VP, respectively, show a single large PCBM-rich core; the insertion of styrene units into the coil block of BCP100 is detrimental for the device efficiency, even if it produces an intermixed structure. Full article

(This article belongs to the Section Solar Energy and Solar Cells)

► Show Figures

Graphical abstract

18 pages, 4083 KiB

Open AccessEditor’s ChoiceArticle

Quantification of STEM Images in High Resolution SEM for Segmented and Pixelated Detectors

by Ivo Konvalina, Aleš Paták, Martin Zouhar, Ilona Müllerová, Tomáš Fořt, Marek Unčovský and Eliška Materna Mikmeková

Nanomaterials 2022, 12(1), 71; https://doi.org/10.3390/nano12010071 - 28 Dec 2021

Cited by 1 | Viewed by 2927

Abstract

The segmented semiconductor detectors for transmitted electrons in ultrahigh resolution scanning electron microscopes allow observing samples in various imaging modes. Typically, two standard modes of objective lens, with and without a magnetic field, differ by their resolution. If the beam deceleration mode is [...] Read more.

The segmented semiconductor detectors for transmitted electrons in ultrahigh resolution scanning electron microscopes allow observing samples in various imaging modes. Typically, two standard modes of objective lens, with and without a magnetic field, differ by their resolution. If the beam deceleration mode is selected, then an electrostatic field around the sample is added. The trajectories of transmitted electrons are influenced by the fields below the sample. The goal of this paper is a quantification of measured images and theoretical study of the capability of the detector to collect signal electrons by its individual segments. Comparison of measured and ray-traced simulated data were difficult in the past. This motivated us to present a new method that enables better comparison of the two datasets at the cost of additional measurements, so-called calibration curves. Furthermore, we also analyze the measurements acquired using 2D pixel array detector (PAD) that provide a more detailed angular profile. We demonstrate that the radial profiles of STEM and/or 2D-PAD data are sensitive to material composition. Moreover, scattering processes are affected by thickness of the sample as well. Hence, comparing the two experimental and simulation data can help to estimate composition or the thickness of the sample. Full article

(This article belongs to the Topic Advances and Applications of 2D Materials)

► Show Figures

Figure 1

20 pages, 6341 KiB

Open AccessEditor’s ChoiceArticle

Structural and Parametric Identification of Knowm Memristors

by Valerii Ostrovskii, Petr Fedoseev, Yulia Bobrova and Denis Butusov

Nanomaterials 2022, 12(1), 63; https://doi.org/10.3390/nano12010063 - 27 Dec 2021

Cited by 42 | Viewed by 4307

Abstract

This paper proposes a novel identification method for memristive devices using Knowm memristors as an example. The suggested identification method is presented as a generalized process for a wide range of memristive elements. An experimental setup was created to obtain a set of [...] Read more.

This paper proposes a novel identification method for memristive devices using Knowm memristors as an example. The suggested identification method is presented as a generalized process for a wide range of memristive elements. An experimental setup was created to obtain a set of intrinsic I–V curves for Knowm memristors. Using the acquired measurements data and proposed identification technique, we developed a new mathematical model that considers low-current effects and cycle-to-cycle variability. The process of parametric identification for the proposed model is described. The obtained memristor model represents the switching threshold as a function of the state variables vector, making it possible to account for snapforward or snapback effects, frequency properties, and switching variability. Several tools for the visual presentation of the identification results are considered, and some limitations of the proposed model are discussed. Full article

(This article belongs to the Special Issue Nanoelectronics, Nanosensors and Devices for Early Career Investigator)

► Show Figures

Figure 1

23 pages, 11133 KiB

Open AccessEditor’s ChoiceArticle

Neurobehavioral and Ultrastructural Changes Induced by Phytosynthesized Silver-Nanoparticle Toxicity in an In Vivo Rat Model

by Razvan Vlad Opris, Vlad Toma, Alina Mihaela Baciu, Remus Moldovan, Bogdan Dume, Alexandra Berghian-Sevastre, Bianca Moldovan, Simona Clichici, Luminita David, Gabriela Adriana Filip and Adrian Florea

Nanomaterials 2022, 12(1), 58; https://doi.org/10.3390/nano12010058 - 26 Dec 2021

Cited by 12 | Viewed by 3352

Abstract

(1) Background: The study aimed to assess neurobehavioral, ultrastructural, and biochemical changes induced by silver nanoparticles synthesized with Cornus mas L. extract (AgNPs-CM) in rat brains. (2) Methods: The study included 36 male adult rats divided into three groups. Over a period of [...] Read more.

(1) Background: The study aimed to assess neurobehavioral, ultrastructural, and biochemical changes induced by silver nanoparticles synthesized with Cornus mas L. extract (AgNPs-CM) in rat brains. (2) Methods: The study included 36 male adult rats divided into three groups. Over a period of 45 days, AgNPs-CM (0.8 and 1.5 mg/kg b.w.) were administered daily by gavage to two of the groups, while the control group received the vehicle used for AgNP. After treatment, OFT and EPM tests were conducted in order to assess neurobehavioral changes. Six of the animals from each group were sacrificed immediately after completion of treatment, while the remaining six were allowed to recuperate for an additional 15 days. Transmission electron microscopy (TEM), GFAP immunohistochemistry, and evaluation of TNFα, IL-6, MDA, and CAT activity were performed on the frontal cortex and hippocampus. (3) Results: Treated animals displayed a dose- and time-dependent increase in anxiety-like behavior and severe ultrastructural changes in neurons, astrocytes, and capillaries in both brain regions. Immunohistochemistry displayed astrogliosis with altered cell morphology. TNFα, IL-6, MDA, and CAT activity were significantly altered, depending on brain region and time post exposure. (4) Conclusions: AgNPs-CM induced neurobehavioral changes and severe cell lesions that continued to escalate after cessation of exposure. Full article

► Show Figures

Figure 1

9 pages, 2242 KiB

Open AccessEditor’s ChoiceArticle

Giving Penetrable Remote-Control Ability to Thermoresponsive Fibrous Composite Actuator with Fast Response Induced by Alternative Magnetic Field

by Li Liu, Wenjing Song, Shaohua Jiang, Gaigai Duan and Xiaohong Qin

Nanomaterials 2022, 12(1), 53; https://doi.org/10.3390/nano12010053 - 25 Dec 2021

Cited by 8 | Viewed by 3062

Abstract

An alternative magnetic field (AMF)-induced electrospun fibrous thermoresponsive composite actuator showing penetrable remote-control ability with fast response is shown here for the first time. The built-in heater of magnetothermal Fe₃O₄ nanoparticles in the actuator and the porous structure of the [...] Read more.

An alternative magnetic field (AMF)-induced electrospun fibrous thermoresponsive composite actuator showing penetrable remote-control ability with fast response is shown here for the first time. The built-in heater of magnetothermal Fe₃O₄ nanoparticles in the actuator and the porous structure of the fibrous layer contribute to a fast actuation with a curvature of 0.4 mm⁻¹ in 2 s. The higher loading amount of the Fe₃O₄ nanoparticles and higher magnetic field strength result in a faster actuation. Interestingly, the composite actuator showed a similar actuation even when it was covered by a piece of Polytetrafluoroethylene (PTFE) film, which shows a penetrable remote-control ability. Full article

► Show Figures

Graphical abstract

12 pages, 3807 KiB

Open AccessEditor’s ChoiceArticle

Effect of Amorphous Crosslinker on Phase Behavior and Electro-Optic Response of Polymer-Stabilized Blue Phase Liquid Crystals

by Kyung Min Lee, Urice Tohgha, Timothy J. Bunning, Michael E. McConney and Nicholas P. Godman

Nanomaterials 2022, 12(1), 48; https://doi.org/10.3390/nano12010048 - 24 Dec 2021

Cited by 6 | Viewed by 2997

Abstract

Blue phase liquid crystals (BPLCs) composed of double-twisted cholesteric helices are promising materials for use in next-generation displays, optical components, and photonics applications. However, BPLCs are only observed in a narrow temperature range of 0.5–3 °C and must be stabilized with a polymer [...] Read more.

Blue phase liquid crystals (BPLCs) composed of double-twisted cholesteric helices are promising materials for use in next-generation displays, optical components, and photonics applications. However, BPLCs are only observed in a narrow temperature range of 0.5–3 °C and must be stabilized with a polymer network. Here, we report on controlling the phase behavior of BPLCs by varying the concentration of an amorphous crosslinker (pentaerythritol triacrylate (PETA)). LC mixtures without amorphous crosslinker display narrow phase transition temperatures from isotropic to the blue phase-II (BP-II), blue phase-I (BP-I), and cholesteric phases, but the addition of PETA stabilizes the BP-I phase. A PETA content above 3 wt% prevents the formation of the simple cubic BP-II phase and induces a direct transition from the isotropic to the BP-I phase. PETA widens the temperature window of BP-I from ~6.8 °C for BPLC without PETA to ~15 °C for BPLC with 4 wt% PETA. The BPLCs with 3 and 4 wt% PETA are stabilized using polymer networks via in situ photopolymerization. Polymer-stabilized BPLC with 3 wt% PETA showed switching between reflective to transparent states with response times of 400–500 μs when an AC field was applied, whereas the application of a DC field induced a large color change from green to red. Full article

(This article belongs to the Special Issue Recent Advances in Nanostructured Liquid Crystals: From Supramolecular Order to Applications)

► Show Figures

Figure 1

18 pages, 1404 KiB

Open AccessEditor’s ChoiceArticle

Cobalt Ferrite Nanoparticles for Tumor Therapy: Effective Heating versus Possible Toxicity

by Anastasiia S. Garanina, Alexey A. Nikitin, Tatiana O. Abakumova, Alevtina S. Semkina, Alexandra O. Prelovskaya, Victor A. Naumenko, Alexander S. Erofeev, Peter V. Gorelkin, Alexander G. Majouga, Maxim A. Abakumov and Ulf Wiedwald

Nanomaterials 2022, 12(1), 38; https://doi.org/10.3390/nano12010038 - 23 Dec 2021

Cited by 33 | Viewed by 4119

Abstract

Magnetic nanoparticles (MNPs) are widely considered for cancer treatment, in particular for magnetic hyperthermia (MHT). Thereby, MNPs are still being optimized for lowest possible toxicity on organisms while the magnetic properties are matched for best heating capabilities. In this study, the biocompatibility of [...] Read more.

Magnetic nanoparticles (MNPs) are widely considered for cancer treatment, in particular for magnetic hyperthermia (MHT). Thereby, MNPs are still being optimized for lowest possible toxicity on organisms while the magnetic properties are matched for best heating capabilities. In this study, the biocompatibility of 12 nm cobalt ferrite MNPs, functionalized with citrate ions, in different dosages on mice and rats of both sexes was investigated for 30 days after intraperitoneal injection. The animals’ weight, behavior, and blood cells changes, as well as blood biochemical parameters are correlated to histological examination of organs revealing that cobalt ferrite MNPs do not have toxic effects at concentrations close to those used previously for efficient MHT. Moreover, these MNPs demonstrated high specific loss power (SLP) of about 400 W g⁻¹. Importantly the MNPs retained their magnetic properties inside tumor tissue after intratumoral administration for several MHT cycles within three days. Thus, cobalt ferrite MNPs represent a perspective platform for tumor therapy by MHT due to their ability to provide effective heating without exerting a toxic effect on the organism. This opens up new avenues for smaller MNPs sizes while their heating efficiency is maintained. Full article

(This article belongs to the Special Issue Novel Magnetic Nanoparticles: Synthesis and Biomedical Applications)

► Show Figures

Graphical abstract

11 pages, 4127 KiB

Open AccessEditor’s ChoiceArticle

Boron Nitride Nanotube-Based Separator for High-Performance Lithium-Sulfur Batteries

by Hong-Sik Kim, Hui-Ju Kang, Hongjin Lim, Hyun Jin Hwang, Jae-Woo Park, Tae-Gyu Lee, Sung Yong Cho, Se Gyu Jang and Young-Si Jun

Nanomaterials 2022, 12(1), 11; https://doi.org/10.3390/nano12010011 - 21 Dec 2021

Cited by 26 | Viewed by 5889

Abstract

To prevent global warming, ESS development is in progress along with the development of electric vehicles and renewable energy. However, the state-of-the-art technology, i.e., lithium-ion batteries, has reached its limitation, and thus the need for high-performance batteries with improved energy and power density [...] Read more.

To prevent global warming, ESS development is in progress along with the development of electric vehicles and renewable energy. However, the state-of-the-art technology, i.e., lithium-ion batteries, has reached its limitation, and thus the need for high-performance batteries with improved energy and power density is increasing. Lithium-sulfur batteries (LSBs) are attracting enormous attention because of their high theoretical energy density. However, there are technical barriers to its commercialization such as the formation of dendrites on the anode and the shuttle effect of the cathode. To resolve these issues, a boron nitride nanotube (BNNT)-based separator is developed. The BNNT is physically purified so that the purified BNNT (p−BNNT) has a homogeneous pore structure because of random stacking and partial charge on the surface due to the difference of electronegativity between B and N. Compared to the conventional polypropylene (PP) separator, the p−BNNT loaded PP separator prevents the dendrite formation on the Li metal anode, facilitates the ion transfer through the separator, and alleviates the shuttle effect at the cathode. With these effects, the p−BNNT loaded PP separators enable the LSB cells to achieve a specific capacity of 1429 mAh/g, and long-term stability over 200 cycles. Full article

(This article belongs to the Special Issue Emerging Nanomaterials for Lithium-Sulfur Batteries and Beyond II)

► Show Figures

Figure 1

11 pages, 3915 KiB

Open AccessEditor’s ChoiceArticle

Scintillation Response Enhancement in Nanocrystalline Lead Halide Perovskite Thin Films on Scintillating Wafers

by Kateřina Děcká, Jan Král, František Hájek, Petr Průša, Vladimir Babin, Eva Mihóková and Václav Čuba

Nanomaterials 2022, 12(1), 14; https://doi.org/10.3390/nano12010014 - 21 Dec 2021

Cited by 24 | Viewed by 6501

Abstract

Lead halide perovskite nanocrystals of the formula CsPbBr₃ have recently been identified as potential time taggers in scintillating heterostructures for time-of-flight positron emission tomography (TOF-PET) imaging thanks to their ultrafast decay kinetics. This study investigates the potential of this material experimentally. We [...] Read more.

Lead halide perovskite nanocrystals of the formula CsPbBr₃ have recently been identified as potential time taggers in scintillating heterostructures for time-of-flight positron emission tomography (TOF-PET) imaging thanks to their ultrafast decay kinetics. This study investigates the potential of this material experimentally. We fabricated CsPbBr₃ thin films on scintillating GGAG:Ce (Gd_2.985Ce_0.015Ga_2.7Al_2.3O₁₂) wafer as a model structure for the future sampling detector geometry. We focused this study on the radioluminescence (RL) response of this composite material. We compare the results of two spin-coating methods, namely the static and the dynamic process, for the thin film preparation. We demonstrated enhanced RL intensity of both CsPbBr₃ and GGAG:Ce scintillating constituents of a composite material. This synergic effect arises in both the RL spectra and decays, including decays in the short time window (50 ns). Consequently, this study confirms the applicability of CsPbBr₃ nanocrystals as efficient time taggers for ultrafast timing applications, such as TOF-PET. Full article

(This article belongs to the Special Issue Thin Films Based on Nanocomposites)

► Show Figures

Graphical abstract

13 pages, 628 KiB

Open AccessEditor’s ChoiceReview

Metal and Metal Oxide Nanoparticles in Caries Prevention: A Review

by Mohammed Zahedul Islam Nizami, Veena W. Xu, Iris X. Yin, Ollie Y. Yu and Chun-Hung Chu

Nanomaterials 2021, 11(12), 3446; https://doi.org/10.3390/nano11123446 - 20 Dec 2021

Cited by 52 | Viewed by 6673

Abstract

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative [...] Read more.

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles’ nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

► Show Figures

Figure 1

11 pages, 980 KiB

Open AccessEditor’s ChoiceArticle

Crystallization in Zirconia Film Nano-Layered with Silica

by Brecken Larsen, Christopher Ausbeck, Timothy F. Bennet, Gilberto DeSalvo, Riccardo DeSalvo, Tugdual LeBohec, Seth Linker, Marina Mondin and Joshua Neilson

Nanomaterials 2021, 11(12), 3444; https://doi.org/10.3390/nano11123444 - 19 Dec 2021

Cited by 7 | Viewed by 3038

Abstract

Gravitational waves are detected using resonant optical cavity interferometers. The mirror coatings’ inherent thermal noise and photon scattering limit sensitivity. Crystals within the reflective coating may be responsible for either or both noise sources. In this study, we explored crystallization reduction in zirconia [...] Read more.

Gravitational waves are detected using resonant optical cavity interferometers. The mirror coatings’ inherent thermal noise and photon scattering limit sensitivity. Crystals within the reflective coating may be responsible for either or both noise sources. In this study, we explored crystallization reduction in zirconia through nano-layering with silica. We used X-ray diffraction (XRD) to monitor crystal growth between successive annealing cycles. We observed crystal formation at higher temperatures in thinner zirconia layers, indicating that silica is a successful inhibitor of crystal growth. However, the thinnest barriers break down at high temperatures, thus allowing crystal growth beyond each nano-layer. In addition, in samples with thicker zirconia layers, we observe that crystallization saturates with a significant portion of amorphous material remaining. Full article

(This article belongs to the Special Issue Metallic Oxide Nanostructures)

► Show Figures

Figure 1

30 pages, 1839 KiB

Open AccessEditor’s ChoiceReview

Microfluidics Technology for the Design and Formulation of Nanomedicines

by Eman Jaradat, Edward Weaver, Adam Meziane and Dimitrios A. Lamprou

Nanomaterials 2021, 11(12), 3440; https://doi.org/10.3390/nano11123440 - 18 Dec 2021

Cited by 40 | Viewed by 7339

Abstract

In conventional drug administration, drug molecules cross multiple biological barriers, distribute randomly in the tissues, and can release insufficient concentrations at the desired pathological site. Controlling the delivery of the molecules can increase the concentration of the drug in the desired location, leading [...] Read more.

In conventional drug administration, drug molecules cross multiple biological barriers, distribute randomly in the tissues, and can release insufficient concentrations at the desired pathological site. Controlling the delivery of the molecules can increase the concentration of the drug in the desired location, leading to improved efficacy, and reducing the unwanted effects of the molecules under investigation. Nanoparticles (NPs), have shown a distinctive potential in targeting drugs due to their unique properties, such as large surface area and quantum properties. A variety of NPs have been used over the years for the encapsulation of different drugs and biologics, acting as drug carriers, including lipid-based and polymeric NPs. Applying NP platforms in medicines significantly improves the disease diagnosis and therapy. Several conventional methods have been used for the manufacturing of drug loaded NPs, with conventional manufacturing methods having several limitations, leading to multiple drawbacks, including NPs with large particle size and broad size distribution (high polydispersity index), besides the unreproducible formulation and high batch-to-batch variability. Therefore, new methods such as microfluidics (MFs) need to be investigated more thoroughly. MFs, is a novel manufacturing method that uses microchannels to produce a size-controlled and monodispersed NP formulation. In this review, different formulation methods of polymeric and lipid-based NPs will be discussed, emphasizing the different manufacturing methods and their advantages and limitations and how microfluidics has the capacity to overcome these limitations and improve the role of NPs as an effective drug delivery system. Full article

(This article belongs to the Special Issue Nanomaterials for Applied Nanotechnology and Nanoscience)

► Show Figures

Figure 1

17 pages, 5973 KiB

Open AccessEditor’s ChoiceArticle

The Effects of the Binder and Buffering Matrix on InSb-Based Anodes for High-Performance Rechargeable Li-Ion Batteries

by Vo Pham Hoang Huy, Il Tae Kim and Jaehyun Hur

Nanomaterials 2021, 11(12), 3420; https://doi.org/10.3390/nano11123420 - 17 Dec 2021

Cited by 9 | Viewed by 3104

Abstract

C-decorated intermetallic InSb (InSb–C) was developed as a novel high-performance anode material for lithium-ion batteries (LIBs). InSb nanoparticles synthesized via a mechanochemical reaction were characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and [...] Read more.

C-decorated intermetallic InSb (InSb–C) was developed as a novel high-performance anode material for lithium-ion batteries (LIBs). InSb nanoparticles synthesized via a mechanochemical reaction were characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX). The effects of the binder and buffering matrix on the active InSb were investigated. Poly(acrylic acid) (PAA) was found to significantly improve the cycling stability owing to its strong hydrogen bonding. The addition of amorphous C to InSb further enhanced mechanical stability and electronic conductivity. As a result, InSb–C demonstrated good electrochemical Li-ion storage performance: a high reversible specific capacity (878 mAh·g⁻¹ at 100 mA·g⁻¹ after 140 cycles) and good rate capability (capacity retention of 98% at 10 A·g⁻¹ as compared to 0.1 A·g⁻¹). The effects of PAA and C were comprehensively studied using cyclic voltammetry, differential capacity plots, ex-situ SEM, and electrochemical impedance spectroscopy (EIS). In addition, the electrochemical reaction mechanism of InSb was revealed using ex-situ XRD. InSb–C exhibited a better performance than many recently reported Sb-based electrodes; thus, it can be considered as a potential anode material in LIBs. Full article

(This article belongs to the Special Issue Nanomaterials for Ion Battery Applications)

► Show Figures

Graphical abstract

38 pages, 8844 KiB

Open AccessEditor’s ChoiceReview

On-Demand Drug Delivery Systems Using Nanofibers

by Baljinder Singh, Kibeom Kim and Myoung-Hwan Park

Nanomaterials 2021, 11(12), 3411; https://doi.org/10.3390/nano11123411 - 16 Dec 2021

Cited by 56 | Viewed by 6374

Abstract

On-demand drug-delivery systems using nanofibers are extensively applicable for customized drug release based on target location and timing to achieve the desired therapeutic effects. A nanofiber formulation is typically created for a certain medication and changing the drug may have a significant impact [...] Read more.

On-demand drug-delivery systems using nanofibers are extensively applicable for customized drug release based on target location and timing to achieve the desired therapeutic effects. A nanofiber formulation is typically created for a certain medication and changing the drug may have a significant impact on the release kinetics from the same delivery system. Nanofibers have several distinguishing features and properties, including the ease with which they may be manufactured, the variety of materials appropriate for processing into fibers, a large surface area, and a complex pore structure. Nanofibers with effective drug-loading capabilities, controllable release, and high stability have gained the interest of researchers owing to their potential applications in on-demand drug delivery systems. Based on their composition and drug-release characteristics, we review the numerous types of nanofibers from the most recent accessible studies. Nanofibers are classified based on their mechanism of drug release, as well as their structure and content. To achieve controlled drug release, a suitable polymer, large surface-to-volume ratio, and high porosity of the nanofiber mesh are necessary. The properties of nanofibers for modified drug release are categorized here as protracted, stimulus-activated, and biphasic. Swellable or degradable polymers are commonly utilized to alter drug release. In addition to the polymer used, the process and ambient conditions can have considerable impacts on the release characteristics of the nanofibers. The formulation of nanofibers is highly complicated and depends on many variables; nevertheless, numerous options are available to accomplish the desired nanofiber drug-release characteristics. Full article

(This article belongs to the Special Issue Current Review in Synthesis, Interfaces, and Nanostructures)

► Show Figures

Figure 1

28 pages, 7223 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Magnetic Nanomaterials for Arterial Embolization and Hyperthermia of Parenchymal Organs Tumors: A Review

by Natalia E. Kazantseva, Ilona S. Smolkova, Vladimir Babayan, Jarmila Vilčáková, Petr Smolka and Petr Saha

Nanomaterials 2021, 11(12), 3402; https://doi.org/10.3390/nano11123402 - 15 Dec 2021

Cited by 12 | Viewed by 3840

Abstract

Magnetic hyperthermia (MH), proposed by R. K. Gilchrist in the middle of the last century as local hyperthermia, has nowadays become a recognized method for minimally invasive treatment of oncological diseases in combination with chemotherapy (ChT) and radiotherapy (RT). One type of MH [...] Read more.

Magnetic hyperthermia (MH), proposed by R. K. Gilchrist in the middle of the last century as local hyperthermia, has nowadays become a recognized method for minimally invasive treatment of oncological diseases in combination with chemotherapy (ChT) and radiotherapy (RT). One type of MH is arterial embolization hyperthermia (AEH), intended for the presurgical treatment of primary inoperable and metastasized solid tumors of parenchymal organs. This method is based on hyperthermia after transcatheter arterial embolization of the tumor’s vascular system with a mixture of magnetic particles and embolic agents. An important advantage of AEH lies in the double effect of embolotherapy, which blocks blood flow in the tumor, and MH, which eradicates cancer cells. Consequently, only the tumor undergoes thermal destruction. This review introduces the progress in the development of polymeric magnetic materials for application in AEH. Full article

(This article belongs to the Special Issue Advanced Magnetic Nanocomposites: Structural, Physical Properties and Application)

► Show Figures

Figure 1

19 pages, 3496 KiB

Open AccessEditor’s ChoiceArticle

Preparation and Characterization of Photocatalytically Active Antibacterial Surfaces Covered with Acrylic Matrix Embedded Nano-ZnO and Nano-ZnO/Ag

by Merilin Rosenberg, Meeri Visnapuu, Kristjan Saal, Dmytro Danilian, Rainer Pärna, Angela Ivask and Vambola Kisand

Nanomaterials 2021, 11(12), 3384; https://doi.org/10.3390/nano11123384 - 14 Dec 2021

Cited by 8 | Viewed by 3256

Abstract

In the context of healthcare-acquired infections, microbial cross-contamination and the spread of antibiotic resistance, additional passive measures to prevent pathogen carryover are urgently needed. Antimicrobial high-touch surfaces that kill microbes on contact or prevent their adhesion could be considered to mitigate the spread. [...] Read more.

In the context of healthcare-acquired infections, microbial cross-contamination and the spread of antibiotic resistance, additional passive measures to prevent pathogen carryover are urgently needed. Antimicrobial high-touch surfaces that kill microbes on contact or prevent their adhesion could be considered to mitigate the spread. Here, we demonstrate that photocatalytic nano-ZnO- and nano-ZnO/Ag-based antibacterial surfaces with efficacy of at least a 2.7-log reduction in Escherichia coli and Staphylococcus aureus viability in 2 h can be produced by simple measures using a commercial acrylic topcoat for wood surfaces. We characterize the surfaces taking into account cyclic wear and variable environmental conditions. The light-induced antibacterial and photocatalytic activities of the surfaces are enhanced by short-term cyclic wear, indicating their potential for prolonged effectivity in long-term use. As the produced surfaces are generally more effective at higher relative air humidity and silver-containing surfaces lost their contact-killing properties in dry conditions, it is important to critically evaluate the end-use conditions of materials and surfaces to be tested and select application-appropriate methods for their efficacy assessment. Full article

(This article belongs to the Special Issue Antimicrobial Nano Coatings)

► Show Figures

Figure 1

11 pages, 3073 KiB

Open AccessEditor’s ChoiceArticle

The Sensitization of Scintillation in Polymeric Composites Based on Fluorescent Nanocomplexes

by Irene Villa, Beatriz Santiago Gonzalez, Matteo Orfano, Francesca Cova, Valeria Secchi, Camilla Colombo, Juraj Páterek, Romana Kučerková, Vladimir Babin, Michele Mauri, Martin Nikl and Angelo Monguzzi

Nanomaterials 2021, 11(12), 3387; https://doi.org/10.3390/nano11123387 - 14 Dec 2021

Cited by 7 | Viewed by 2667

Abstract

The sensitization of scintillation was investigated in crosslinked polymeric composite materials loaded with luminescent gold clusters aggregates acting as sensitizers, and with organic dye rhodamine 6G as the emitting species. The evolution in time of the excited states population in the systems is [...] Read more.

The sensitization of scintillation was investigated in crosslinked polymeric composite materials loaded with luminescent gold clusters aggregates acting as sensitizers, and with organic dye rhodamine 6G as the emitting species. The evolution in time of the excited states population in the systems is described by a set of coupled rate equations, in which steady state solution allowed obtainment of an expression of the sensitization efficacy as a function of the characteristic parameters of the employed luminescent systems. The results obtained indicate that the realization of sensitizer/emitter scintillating complexes is the strategy that must be pursued to maximize the sensitization effect in composite materials. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Radiation Applications)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Editor’s Choice Articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI