Nanomaterials

13 pages, 6364 KiB

Open AccessEditor’s ChoiceArticle

Laser-Induced Modification of Hydrogenated Detonation Nanodiamonds in Ethanol

by Irena Bydzovska, Ekaterina Shagieva, Ivan Gordeev, Oleksandr Romanyuk, Zuzana Nemeckova, Jiri Henych, Lukas Ondic, Alexander Kromka and Stepan Stehlik

Nanomaterials 2021, 11(9), 2251; https://doi.org/10.3390/nano11092251 - 31 Aug 2021

Cited by 7 | Viewed by 2999

Abstract

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which [...] Read more.

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which were irradiated for up to 60 min using a 532 nm NdYAG laser with an energy of 150 mJ in a pulse (5 J/cm²) at a pulse duration of 10 ns and a repetition rate of 10 Hz. We investigated the DND surface chemistry, zeta potential, and structure as a function of laser irradiation time. Infrared spectroscopy revealed a monotonical decrease in the C–H_x band intensities and an increase of the C–O and C=O features. Transmission electron microscopy (TEM) revealed the formation of OLC, as well as a gradual loss of nanoparticle character, with increasing irradiation time. Surprisingly, for samples irradiated up to 40 min, the typical and unchanged DND Raman spectrum was recovered after their annealing in air at 450 °C for 300 min. This finding indicates the inhomogeneous sp³ to sp² carbon transformation during laser irradiation, as well as the insensitivity of DND Raman spectra to surface chemistry, size, and transient structural changes. Full article

(This article belongs to the Special Issue Synthesis, Functionalization and Applications of Nanocarbons)

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16 pages, 3577 KiB

Open AccessEditor’s ChoiceArticle

Effect of Silver Modification on the Photoactivity of Titania Coatings with Different Pore Structures

by Borbála Tegze, Emőke Albert, Boglárka Dikó, Norbert Nagy, Adél Rácz, György Sáfrán, Attila Sulyok and Zoltán Hórvölgyi

Nanomaterials 2021, 11(9), 2240; https://doi.org/10.3390/nano11092240 - 30 Aug 2021

Cited by 7 | Viewed by 2202

Abstract

Nanostructured photoactive systems are promising for applications such as air and water purification, including self-cleaning coatings. In this study, mesoporous TiO₂ sol-gel coatings with different pore structures were prepared and modified with silver by two methods: the “mixing” method by adding AgNO [...] Read more.

Nanostructured photoactive systems are promising for applications such as air and water purification, including self-cleaning coatings. In this study, mesoporous TiO₂ sol-gel coatings with different pore structures were prepared and modified with silver by two methods: the “mixing” method by adding AgNO₃ to the precursor sol, and the “impregnation” method by immersing the samples in AgNO₃ solution (0.03 and 1 M) followed by heat treatment. Our aim was to investigate the effects that silver modification has on the functional properties (e.g., those that are important for self-cleaning coatings). Transmittance, band gap energy, refractive index, porosity and thickness values were determined from UV-Vis spectroscopy measurements. Silver content and structure of the silver modified samples were characterized by X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, High-resolution transmission electron microscopy and Energy Dispersive X-ray Spectrometry elemental mapping measurements. Wettability properties, including photoinduced wettability conversion behavior were investigated by water contact angle measurements. Photoactivity was studied under both UV and visible light with rhodamine 6G and methylene blue dye molecules, at the liquid–solid and air–solid interfaces modeling the operating conditions of self-cleaning coatings. Samples made with “impregnation” method showed better functional properties, in spite of their significantly lower silver content. The pore structure influenced the Ag content achieved by the “impregnation” method, and consequently affected their photoactivity. Full article

(This article belongs to the Special Issue Latest Developments in Photocatalytic Materials and Processes)

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17 pages, 3799 KiB

Open AccessEditor’s ChoiceReview

Anisotropic Silver Nanomaterials by Photochemical Reactions: Synthesis and Applications

by Vittorio Scardaci

Nanomaterials 2021, 11(9), 2226; https://doi.org/10.3390/nano11092226 - 29 Aug 2021

Cited by 8 | Viewed by 3239

Abstract

Silver-based nanoparticles have attracted a broad interest due to their outstanding optical and chemical properties and have been studied for applications in many fields. While different synthetic routes have been explored, photochemical synthesis has attracted a special interest for its limited use of [...] Read more.

Silver-based nanoparticles have attracted a broad interest due to their outstanding optical and chemical properties and have been studied for applications in many fields. While different synthetic routes have been explored, photochemical synthesis has attracted a special interest for its limited use of chemicals and ease of control over the shape and size of the nanoparticles. This paper reviews the main factors affecting the synthesis of anisotropic silver nanoparticles, such as irradiation wavelength, pH, etc., and the role of specific key molecules, such as citrate. The paper is structured into different sections depending on how the synthesis is initiated; thus, after the introduction, the photochemical conversion reaction starting from nanoparticles, or seeds, obtained chemically, is covered, followed by reactions from nanoparticles obtained by laser ablation by seedless reactions. After that, the applications proposed for anisotropic nanoparticles obtained by the methods discussed in the previous sections are briefly covered and, finally, the conclusions and the author’s perspectives are given. Full article

(This article belongs to the Special Issue Advanced Noble Metal Nanoparticles)

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21 pages, 9779 KiB

Open AccessEditor’s ChoiceArticle

Preparation of Metal Nitride Particles Using Arc Discharge in Liquid Nitrogen

by Yoon Sik Park, Satoshi Kodama and Hidetoshi Sekiguchi

Nanomaterials 2021, 11(9), 2214; https://doi.org/10.3390/nano11092214 - 28 Aug 2021

Cited by 12 | Viewed by 4708

Abstract

A simple process to synthesize metal nitride particles was proposed using submerged arc discharge plasma in liquid nitrogen. Gibbs standard free energy was considered for the selection of the nitride-forming materials. In this study, titanium (Ti) and aluminum (Al) electrodes were used as [...] Read more.

A simple process to synthesize metal nitride particles was proposed using submerged arc discharge plasma in liquid nitrogen. Gibbs standard free energy was considered for the selection of the nitride-forming materials. In this study, titanium (Ti) and aluminum (Al) electrodes were used as raw materials for nitride particle preparation. Liquid nitrogen acted as a dielectric medium as well as a nitridation source in this process. A copper electrode was also used as a non-reactive material for comparison with the reactive Ti and Al electrodes. As the operating conditions of the experiments, the arc discharge current was varied from 5 A (low-power mode) to 30 A (high-power mode). The formation of titanium nitride (TiN) and aluminum nitride (AlN) was confirmed in the particles prepared in all experimental conditions by X-ray powder diffraction (XRD). The observation using a field emission scanning electron microscope (FE-SEM) and a field emission transmission electron microscope (FE-TEM) indicated that the synthesized TiN particles showed a cubic morphology, whereas AlN particles containing unreacted Al showed a spherical morphology. The experiments using different metal electrode configurations showed that the anode generated most of the particles in this process. Based on the obtained results, a particle formation mechanism was proposed. Full article

(This article belongs to the Special Issue Plasma Based Nanomaterials and Their Applications)

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10 pages, 6347 KiB

Open AccessEditor’s ChoiceArticle

Oxygen Concentration Effect on Conductive Bridge Random Access Memory of InWZnO Thin Film

by Chih-Chieh Hsu, Po-Tsun Liu, Kai-Jhih Gan, Dun-Bao Ruan and Simon M. Sze

Nanomaterials 2021, 11(9), 2204; https://doi.org/10.3390/nano11092204 - 27 Aug 2021

Cited by 5 | Viewed by 3483

Abstract

In this study, the influence of oxygen concentration in InWZnO (IWZO), which was used as the switching layer of conductive bridge random access memory, (CBRAM) is investigated. With different oxygen flow during the sputtering process, the IWZO film can be fabricated with different [...] Read more.

In this study, the influence of oxygen concentration in InWZnO (IWZO), which was used as the switching layer of conductive bridge random access memory, (CBRAM) is investigated. With different oxygen flow during the sputtering process, the IWZO film can be fabricated with different oxygen concentrations and different oxygen vacancy distribution. In addition, the electrical characteristics of CBRAM device with different oxygen concentration are compared and further analyzed with an atomic force microscope and X-ray photoelectron spectrum. Furthermore, a stacking structure with different bilayer switching is also systematically discussed. Compared with an interchange stacking layer and other single layer memory, the CBRAM with specific stacking sequence of bilayer oxygen-poor/-rich IWZO (IWZOx/IWZOy, x < y) exhibits more stable distribution of a resistance state and also better endurance (more than 3 × 10⁴ cycles). Meanwhile, the memory window of IWZOx/IWZOy can even be maintained over 10⁴ s at 85 °C. Those improvements can be attributed to the oxygen vacancy distribution in switching layers, which may create a suitable environment for the conductive filament formation or rupture. Therefore, it is believed that the specific stacking bilayer IWZO CBRAM might further pave the way for emerging memory applications. Full article

(This article belongs to the Special Issue Nanomaterials for Electron Devices)

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21 pages, 4112 KiB

Open AccessEditor’s ChoiceArticle

Effect of Artemisinin-Loaded Mesoporous Cerium-Doped Calcium Silicate Nanopowder on Cell Proliferation of Human Periodontal Ligament Fibroblasts

by Ioannis Tsamesidis, Dimitrios Gkiliopoulos, Georgia K. Pouroutzidou, Evgenia Lymperaki, Chrysanthi Papoulia, Karine Reybier, Pierre Perio, Konstantinos M. Paraskevopoulos, Eleana Kontonasaki and Anna Theocharidou

Nanomaterials 2021, 11(9), 2189; https://doi.org/10.3390/nano11092189 - 26 Aug 2021

Cited by 22 | Viewed by 3742

Abstract

Ion doping has rendered mesoporous structures important materials in the field of tissue engineering, as apart from drug carriers, they can additionally serve as regenerative materials. The purpose of the present study was the synthesis, characterization and evaluation of the effect of artemisinin [...] Read more.

Ion doping has rendered mesoporous structures important materials in the field of tissue engineering, as apart from drug carriers, they can additionally serve as regenerative materials. The purpose of the present study was the synthesis, characterization and evaluation of the effect of artemisinin (ART)-loaded cerium-doped mesoporous calcium silicate nanopowders (NPs) on the hemocompatibility and cell proliferation of human periodontal ligament fibroblasts (hPDLFs). Mesoporous NPs were synthesized in a basic environment via a surfactant assisted cooperative self-assembly process and were characterized using Scanning Electron Microscopy (SEM), X-ray Fluorescence Spectroscopy (XRF), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction Analysis (XRD) and N2 Porosimetry. The loading capacity of NPs was evaluated using Ultrahigh Performance Liquid Chromatography/High resolution Mass Spectrometry (UHPLC/HRMS). Their biocompatibility was evaluated with the MTT assay, and the analysis of reactive oxygen species was performed using the cell-permeable ROS-sensitive probe 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA). The synthesized NPs presented a mesoporous structure with a surface area ranging from 1312 m²/g for undoped silica to 495 m²/g for the Ce-doped NPs, excellent bioactivity after a 1-day immersion in c-SBF, hemocompatibility and a high loading capacity (around 80%). They presented ROS scavenging properties, and both the unloaded and ART-loaded NPs significantly promoted cell proliferation even at high concentrations of NPs (125 μg/mL). The ART-loaded Ce-doped NPs with the highest amount of cerium slightly restricted cell proliferation after 7 days of culture, but the difference was not significant compared with the control untreated cells. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Nanomaterials for Advanced Tissue Engineering Applications)

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13 pages, 9827 KiB

Open AccessEditor’s ChoiceArticle

Introduction of Rare-Earth Oxide Nanoparticles in CNT-Based Nanocomposites for Improved Detection of Underlying CNT Network

by Joel Hubbard, Tugba Isik, Troy Y. Ansell, Volkan Ortalan and Claudia Luhrs

Nanomaterials 2021, 11(9), 2168; https://doi.org/10.3390/nano11092168 - 25 Aug 2021

Cited by 2 | Viewed by 2596

Abstract

Epoxy resins for adhesive and structural applications are widely employed by various industries. The introduction of high aspect ratio nanometric conductive fillers, i.e., carbon nanotubes, are well studied and are known to improve the electrical properties of the bulk material by orders of [...] Read more.

Epoxy resins for adhesive and structural applications are widely employed by various industries. The introduction of high aspect ratio nanometric conductive fillers, i.e., carbon nanotubes, are well studied and are known to improve the electrical properties of the bulk material by orders of magnitude. This improved electrical conductivity has made carbon nanotube-based nanocomposites an attractive material for applications where their weight savings are at a premium. However, the analytical methods for validating carbon nanotube (CNT) nanofiller dispersion and for assuring that the properties they induce extend to the entire volume are destructive and inhibited by poor resolution between matrix and tube bundles. Herein, rare-earth oxide nanoparticles are synthesized on CNT walls for the purpose of increasing the contrast between their network and the surrounding matrix when studied by imaging techniques, alleviating these issues. The adherence of the synthesized nanoparticles to the CNT walls is documented via transmission electron microscopy. The crystalline phases generated during the various fabrication steps are determined using X-ray diffraction. Deep ultraviolet-induced fluorescence of the Eu:Y₂O₃-CNT nanostructures is verified. The impacts to nanocomposite electrical properties resulting from dopant introduction are characterized. The scanning electron microscopy imaging of CNT pulp and nanocomposites fabricated from untreated CNTs and Eu:Y₂O₃-CNTs are compared, resulting in improved contrast and detection of CNT bundles. The micro-CT scans of composites with similar results are presented for discussion. Full article

(This article belongs to the Special Issue Carbon-Based Nanocomposites)

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15 pages, 1282 KiB

Open AccessEditor’s ChoiceArticle

Design, Synthesis, and Cytotoxicity Assessment of [⁶⁴Cu]Cu-NOTA-Terpyridine Platinum Conjugate: A Novel Chemoradiotherapeutic Agent with Flexible Linker

by Meysam Khosravifarsani, Samia Ait-Mohand, Benoit Paquette, Léon Sanche and Brigitte Guérin

Nanomaterials 2021, 11(9), 2154; https://doi.org/10.3390/nano11092154 - 24 Aug 2021

Cited by 15 | Viewed by 3829

Abstract

Maximum benefits of chemoradiation therapy with platinum-based compounds are expected if the radiation and the drug are localized simultaneously in cancer cells. To optimize this concomitant effect, we developed the novel chemoradiotherapeutic agent [⁶⁴Cu]Cu-NOTA-C3-TP by conjugating, via a short flexible alkyl [...] Read more.

Maximum benefits of chemoradiation therapy with platinum-based compounds are expected if the radiation and the drug are localized simultaneously in cancer cells. To optimize this concomitant effect, we developed the novel chemoradiotherapeutic agent [⁶⁴Cu]Cu-NOTA-C3-TP by conjugating, via a short flexible alkyl chain spacer (C3), a terpyridine platinum (TP) moiety to a NOTA chelator complexed with copper-64 (⁶⁴Cu). The decay of ⁶⁴Cu produces numerous low-energy electrons, enabling the ⁶⁴Cu-conjugate to deliver radiation energy close to TP, which intercalates into G-quadruplex DNA. Accordingly, the in vitro internalization kinetic and the cytotoxic activity of [⁶⁴Cu]Cu-NOTA-C3-TP and its derivatives were investigated with colorectal cancer (HCT116) and normal human fibroblast (GM05757) cells. Radiolabeling by ⁶⁴Cu results in a >55,000-fold increase of cytotoxic potential relative to [^NatCu]Cu-NOTA-C3-TP at 72 h post administration, indicating a large additive effect between ⁶⁴Cu and the TP drug. The internalization and nucleus accumulation of [⁶⁴Cu]Cu-NOTA-C3-TP in the HCT116 cells were, respectively, 3.1 and 6.0 times higher than that for GM05757 normal human fibroblasts, which is supportive of the higher efficiency of the [⁶⁴Cu]Cu-NOTA-C3-TP for HCT116 cancer cells. This work presents the first proof-of-concept study showing the potential use of the [⁶⁴Cu]Cu-NOTA-C3-TP conjugate as a targeted chemoradiotherapeutic agent to treat colorectal cancer. Full article

(This article belongs to the Special Issue Recent Advances in Cancer Nanotechnology)

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19 pages, 4009 KiB

Open AccessEditor’s ChoiceArticle

Unravelling the Role of Synthesis Conditions on the Structure of Zinc Oxide-Reduced Graphene Oxide Nanofillers

by Zélia Alves, Cláudia Nunes and Paula Ferreira

Nanomaterials 2021, 11(8), 2149; https://doi.org/10.3390/nano11082149 - 23 Aug 2021

Cited by 17 | Viewed by 3492

Abstract

The diversity of zinc oxide (ZnO) particles and derived composites applications is highly dependent on their structure, size, morphology, defect amounts, and/or presence of dopant molecules. In this work, ZnO nanostructures are grown in situ on graphene oxide (GO) sheets by an easily [...] Read more.

The diversity of zinc oxide (ZnO) particles and derived composites applications is highly dependent on their structure, size, morphology, defect amounts, and/or presence of dopant molecules. In this work, ZnO nanostructures are grown in situ on graphene oxide (GO) sheets by an easily implementable solvothermal method with simultaneous reduction of GO. The effect of two zinc precursors (zinc acetate (ZA) and zinc acetate dihydrate (ZAD)), NaOH concentration (0.5, 1 or 2 M), and concentration (1 and 12.5 mg/mL) and pH (pH = 1, 4, 8, and 12) of GO suspension were evaluated. While the ZnO particle morphology shows to be precursor dependent, the average particle size length decreases with lower NaOH concentration, as well as with the addition of a higher basicity and concentration of GO suspension. A lowered band gap and a higher specific surface area are obtained from the ZnO composites with higher amounts of GO suspension. Otherwise, the low concentration and the higher pH of GO suspension induce more lattice defects on the ZnO crystal structure. The role of the different condition parameters on the ZnO nanostructures and their interaction with graphene sheets was observed to tune the ZnO–rGO nanofiller properties for photocatalytic and antimicrobial activities. Full article

(This article belongs to the Special Issue Synthesis, Characteristics, and Applications of Nanocomposites)

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13 pages, 5837 KiB

Open AccessEditor’s ChoiceArticle

Skin Sensitization Potential and Cellular ROS-Induced Cytotoxicity of Silica Nanoparticles

by Sung-Hyun Kim, Dong Han Lee, SeoYoon Choi, Jun-Young Yang, Kikyung Jung, Jayoung Jeong, Jae Ho Oh and Jin Hee Lee

Nanomaterials 2021, 11(8), 2140; https://doi.org/10.3390/nano11082140 - 22 Aug 2021

Cited by 15 | Viewed by 3662

Abstract

Nowadays, various industries using nanomaterials are growing rapidly, and in particular, as the commercialization and use of nanomaterials increase in the cosmetic field, the possibility of exposure of nanomaterials to the skin of product producers and consumers is increasing. Due to the unique [...] Read more.

Nowadays, various industries using nanomaterials are growing rapidly, and in particular, as the commercialization and use of nanomaterials increase in the cosmetic field, the possibility of exposure of nanomaterials to the skin of product producers and consumers is increasing. Due to the unique properties of nanomaterials with a very small size, they can act as hapten and induce immune responses and skin sensitization, so accurate identification of toxicity is required. Therefore, we selected silica nanomaterials used in various fields such as cosmetics and biomaterials and evaluated the skin sensitization potential step-by-step according to in-vitro and in-vivo alternative test methods. KeratinoSens^TM cells of modified keratinocyte and THP-1 cells mimicking dendritic-cells were treated with silica nanoparticles, and their potential for skin sensitization and cytotoxicity were evaluated, respectively. We also confirmed the sensitizing ability of silica nanoparticles in the auricle-lymph nodes of BALB/C mice by in-vivo analysis. As a result, silica nanoparticles showed high protein binding and reactive oxygen species (ROS) mediated cytotoxicity, but no significant observation of skin sensitization indicators was observed. Although more studies are needed to elucidate the mechanism of skin sensitization by nanomaterials, the results of this study showed that silica nanoparticles did not induce skin sensitization. Full article

(This article belongs to the Special Issue Biological and Toxicological Studies of Nanoparticles)

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13 pages, 2444 KiB

Open AccessEditor’s ChoiceArticle

Chlorosulfonic Acid Stretched Carbon Nanotube Sheet for Flexible and Low-Voltage Heating Applications

by Daniel Rui Chen, Megha Chitranshi, Paa Kwasi Adusei, Mark Schulz, Vesselin Shanov and Marc M. Cahay

Nanomaterials 2021, 11(8), 2132; https://doi.org/10.3390/nano11082132 - 21 Aug 2021

Cited by 8 | Viewed by 3205

Abstract

The carbon nanotube (CNT) is celebrated for its electrothermal property, which indicates the capability of a material to transform electrical energy into heat due to the Joule effect. The CNT nanostructure itself, as a one-dimensional material, limits the electron conduction path, thereby creating [...] Read more.

The carbon nanotube (CNT) is celebrated for its electrothermal property, which indicates the capability of a material to transform electrical energy into heat due to the Joule effect. The CNT nanostructure itself, as a one-dimensional material, limits the electron conduction path, thereby creating a unique heating phenomenon. In this work, we explore the possible correlation between CNT alignment in sheets and heating performance. The alignment of carbon nanotubes is induced by immersion and stretching in chlorosulfonic acid (CSA) solution. The developed CSA-stretched CNT sheet demonstrated excellent heating performance with a fast response rate of 6.5 °C/s and reached 180 °C in less than 30 s under a low voltage of 2.5 V. The heating profile of the stretched CNT sheet remained stable after bending and twisting movements, making it a suitable heating material for wearable devices, heatable smart windows, and in de-icing or defogging applications. The specific strength and specific conductance of the CSA-stretched CNT sheet also increased five- and two-fold, respectively, in comparison to the pristine CNT sheet. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Graphene and Carbon Nanotubes)

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10 pages, 2215 KiB

Open AccessEditor’s ChoiceArticle

Characteristic Variabilities of Subnanometer EOT La₂O₃ Gate Dielectric Film of Nano CMOS Devices

by Hei Wong, Jieqiong Zhang, Hiroshi Iwai and Kuniyuki Kakushima

Nanomaterials 2021, 11(8), 2118; https://doi.org/10.3390/nano11082118 - 20 Aug 2021

Cited by 9 | Viewed by 2997

Abstract

As CMOS devices are scaled down to a nanoscale range, characteristic variability has become a critical issue for yield and performance control of gigascale integrated circuit manufacturing. Nanoscale in size, few monolayers thick, and less thermally stable high-k interfaces all together cause more [...] Read more.

As CMOS devices are scaled down to a nanoscale range, characteristic variability has become a critical issue for yield and performance control of gigascale integrated circuit manufacturing. Nanoscale in size, few monolayers thick, and less thermally stable high-k interfaces all together cause more significant surface roughness-induced local electric field fluctuation and thus leads to a large device characteristic variability. This paper presents a comprehensive study and detailed discussion on the gate leakage variabilities of nanoscale devices corresponding to the surface roughness effects. By taking the W/La₂O₃/Si structure as an example, capacitance and leakage current variabilities were found to increase pronouncedly for samples even with a very low-temperature thermal annealing at 300 °C. These results can be explained consistently with the increase in surface roughness as a result of local oxidation at the La₂O₃/Si interface and the interface reactions at the W/La₂O₃ interface. The surface roughness effects are expected to be severe in future generations’ devices with even thinner gate dielectric film and smaller size of the devices. Full article

(This article belongs to the Special Issue Abridging the CMOS Technology)

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17 pages, 3060 KiB

Open AccessEditor’s ChoiceArticle

Graphene Oxide and Reduced Graphene Oxide Nanoflakes Coated with Glycol Chitosan, Propylene Glycol Alginate, and Polydopamine: Characterization and Cytotoxicity in Human Chondrocytes

by Lorenzo Vannozzi, Enrico Catalano, Madina Telkhozhayeva, Eti Teblum, Alina Yarmolenko, Efrat Shawat Avraham, Rajashree Konar, Gilbert Daniel Nessim and Leonardo Ricotti

Nanomaterials 2021, 11(8), 2105; https://doi.org/10.3390/nano11082105 - 19 Aug 2021

Cited by 25 | Viewed by 5104

Abstract

Recently, graphene and its derivatives have been extensively investigated for their interesting properties in many biomedical fields, including tissue engineering and regenerative medicine. Nonetheless, graphene oxide (GO) and reduced GO (rGO) are still under investigation for improving their dispersibility in aqueous solutions and [...] Read more.

Recently, graphene and its derivatives have been extensively investigated for their interesting properties in many biomedical fields, including tissue engineering and regenerative medicine. Nonetheless, graphene oxide (GO) and reduced GO (rGO) are still under investigation for improving their dispersibility in aqueous solutions and their safety in different cell types. This work explores the interaction of GO and rGO with different polymeric dispersants, such as glycol chitosan (GC), propylene glycol alginate (PGA), and polydopamine (PDA), and their effects on human chondrocytes. GO was synthesized using Hummer’s method, followed by a sonication-assisted liquid-phase exfoliation (LPE) process, drying, and thermal reduction to obtain rGO. The flakes of GO and rGO exhibited an average lateral size of 8.8 ± 4.6 and 18.3 ± 8.5 µm, respectively. Their dispersibility and colloidal stability were investigated in the presence of the polymeric surfactants, resulting in an improvement in the suspension stability in terms of average size and polydispersity index over 1 h, in particular for PDA. Furthermore, cytotoxic effects induced by coated and uncoated GO and rGO on human chondrocytes at different concentrations (12.5, 25, 50 and 100 µg/mL) were assessed through LDH assay. Results showed a concentration-dependent response, and the presence of PGA contributed to statistically decreasing the difference in the LDH activity with respect to the control. These results open the way to a potentially safer use of these nanomaterials in the fields of cartilage tissue engineering and regenerative medicine. Full article

(This article belongs to the Special Issue Cytotoxicity and Genotoxicity of Nanomaterials)

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10 pages, 3746 KiB

Open AccessEditor’s ChoiceCommunication

Anion Dependent Particle Size Control of Platinum Nanoparticles Synthesized in Ethylene Glycol

by Johanna Schröder, Sarah Neumann, Jonathan Quinson, Matthias Arenz and Sebastian Kunz

Nanomaterials 2021, 11(8), 2092; https://doi.org/10.3390/nano11082092 - 18 Aug 2021

Cited by 8 | Viewed by 4163

Abstract

The polyol synthesis is a well-established method to form so-called “surfactant-free” nanoparticles (NPs). In the present study, the NP size resulting from the thermal reduction of the precursors H₂PtCl₆, H₂Pt(OH)₆, or Pt(acac)₂ in presence [...] Read more.

The polyol synthesis is a well-established method to form so-called “surfactant-free” nanoparticles (NPs). In the present study, the NP size resulting from the thermal reduction of the precursors H₂PtCl₆, H₂Pt(OH)₆, or Pt(acac)₂ in presence of the bases NaOH or Na(acac) at different concentrations is studied. It is shown that the size control depends more strongly on the nature of the precursor (metal salt) than on the anion present in the base. The latter is surprising as the concentration of the base anion is often an important factor to achieve a size control. The reduction of H₂PtCl₆ or H₂Pt(OH)₆ in presence of NaOH and Na(acac) confirm the observation that the NP size is determined by the OH⁻/Pt molar ratio and expands it to the base anion/Pt molar ratio. In contrast, the reduction of Pt(acac)₂ in presence of the bases NaOH (previous reports) or Na(acac) (shown in the present work) leads to larger NPs of ca. 3 nm, independent of the concentration of the base anions. Hence, the anion effect observed here seems to originate predominantly from the nature of the precursor (precursor anion dependence) and only for certain precursors as H₂PtCl₆ or H₂Pt(OH)₆ the size control depends on the base anion/Pt molar ratio. Full article

(This article belongs to the Special Issue Surfactant-Free Syntheses of Precious Metal Nanoparticles)

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26 pages, 3389 KiB

Open AccessEditor’s ChoiceArticle

Coupling between Polymer Conformations and Dynamics Near Amorphous Silica Surfaces: A Direct Insight from Atomistic Simulations

by Petra Bačová, Wei Li, Alireza F. Behbahani, Craig Burkhart, Patrycja Polińska, Manolis Doxastakis and Vagelis Harmandaris

Nanomaterials 2021, 11(8), 2075; https://doi.org/10.3390/nano11082075 - 16 Aug 2021

Cited by 15 | Viewed by 3269

Abstract

The dynamics of polymer chains in the polymer/solid interphase region have been a point of debate in recent years. Its understanding is the first step towards the description and the prediction of the properties of a wide family of commercially used polymeric-based nanostructured [...] Read more.

The dynamics of polymer chains in the polymer/solid interphase region have been a point of debate in recent years. Its understanding is the first step towards the description and the prediction of the properties of a wide family of commercially used polymeric-based nanostructured materials. Here, we present a detailed investigation of the conformational and dynamical features of unentangled and mildly entangled cis-1,4-polybutadiene melts in the vicinity of amorphous silica surface via atomistic simulations. Accounting for the roughness of the surface, we analyze the properties of the polymer chains as a function of their distance from the silica slab, their conformations and the chain molecular weight. Unlike the case of perfectly flat and homogeneous surfaces, the monomeric translational motion parallel to the surface was affected by the presence of the silica slab up to distances comparable with the extension of the density fluctuations. In addition, the intramolecular dynamical heterogeneities in adsorbed chains were revealed by linking the conformations and the structure of the adsorbed chains with their dynamical properties. Strong dynamical heterogeneities within the adsorbed layer are found, with the chains possessing longer sequences of adsorbed segments (“trains”) exhibiting slower dynamics than the adsorbed chains with short ones. Our results suggest that, apart from the density-dynamics correlation, the configurational entropy plays an important role in the dynamical response of the polymers confined between the silica slabs. Full article

(This article belongs to the Special Issue Advances in Computational Materials Science on Functional Interfaces and Surfaces)

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8 pages, 2159 KiB

Open AccessEditor’s ChoiceArticle

Advantages of InGaN–GaN–InGaN Delta Barriers for InGaN-Based Laser Diodes

by Liwen Cheng, Zhenwei Li, Jiayi Zhang, Xingyu Lin, Da Yang, Haitao Chen, Shudong Wu and Shun Yao

Nanomaterials 2021, 11(8), 2070; https://doi.org/10.3390/nano11082070 - 15 Aug 2021

Cited by 8 | Viewed by 2847

Abstract

An InGaN laser diode with InGaN–GaN–InGaN delta barriers was designed and investigated numerically. The laser power–current–voltage performance curves, carrier concentrations, current distributions, energy band structures, and non-radiative and stimulated recombination rates in the quantum wells were characterized. The simulations indicate that an InGaN [...] Read more.

An InGaN laser diode with InGaN–GaN–InGaN delta barriers was designed and investigated numerically. The laser power–current–voltage performance curves, carrier concentrations, current distributions, energy band structures, and non-radiative and stimulated recombination rates in the quantum wells were characterized. The simulations indicate that an InGaN laser diode with InGaN–GaN–InGaN delta barriers has a lower turn-on current, a higher laser power, and a higher slope efficiency than those with InGaN or conventional GaN barriers. These improvements originate from modified energy bands of the laser diodes with InGaN–GaN–InGaN delta barriers, which can suppress electron leakage out of, and enhance hole injection into, the active region. Full article

(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)

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14 pages, 10378 KiB

Open AccessEditor’s ChoiceArticle

Charge-Transfer Process in Surface-Enhanced Raman Scattering Based on Energy Level Locations of Rare-Earth Nd³⁺-Doped TiO₂ Nanoparticles

by Zihao Zhao, Xiang Zhao, Mu Zhang and Xudong Sun

Nanomaterials 2021, 11(8), 2063; https://doi.org/10.3390/nano11082063 - 14 Aug 2021

Cited by 12 | Viewed by 3992

Abstract

Surface-enhanced Raman scattering (SERS) for semiconductor nanomaterial systems is limited due to weak Raman signal intensity and unclear charge-transfer (CT) processes for chemical enhancement. Here, rare-earth element neodymium-doped titanium dioxide (Nd-TiO₂) nanoparticles (NPs) were synthesized by the sol–gel method. The characterizations [...] Read more.

Surface-enhanced Raman scattering (SERS) for semiconductor nanomaterial systems is limited due to weak Raman signal intensity and unclear charge-transfer (CT) processes for chemical enhancement. Here, rare-earth element neodymium-doped titanium dioxide (Nd-TiO₂) nanoparticles (NPs) were synthesized by the sol–gel method. The characterizations show that the doping of Nd ions causes TiO₂ NPs to show an increase in the concentration of defects and change in the energy level structure. The CT process between Nd-TiO₂ NPs substrate and probe molecule 4-Mercaptopyridine (4-Mpy) was innovatively analyzed using the relative energy level location relationship of the Dorenbos model. The SERS signal intensity exhibits an exponential enhancement with increasing Nd doping concentration and reaches its optimum at 2%, which is attributed to two factors: (1) The increase in the defect concentration is beneficial to the CT process between the TiO₂ and the probe molecule; (2) the introduction of 4f electron orbital energy levels of rare-earth ions created unique CT process between Nd³⁺ and 4-Mpy. Moreover, the Nd-TiO₂ NPs substrate shows excellent SERS performance in Raman signal reproducibility (RSD = 5.31%), the limit of detection (LOD = 10⁻⁶ M), and enhancement factor (EF = 3.79 × 10⁴). Our work not only improves the SERS performance of semiconductor substrates but also provides a novel approach to the development of selective detection of probe molecules. Full article

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10 pages, 3092 KiB

Open AccessEditor’s ChoiceArticle

Triple-Band Anisotropic Perfect Absorbers Based on α-Phase MoO₃ Metamaterials in Visible Frequencies

by Bin Tang, Neigang Yang, Xianglian Song, Gui Jin and Jiangbin Su

Nanomaterials 2021, 11(8), 2061; https://doi.org/10.3390/nano11082061 - 13 Aug 2021

Cited by 21 | Viewed by 3118

Abstract

Anisotropic materials provide a new platform for building diverse polarization-dependent optical devices. Two-dimensional α-phase molybdenum trioxides (α-MoO₃), as newly emerging natural van der Waals materials, have attracted significant attention due to their unique anisotropy. In this work, we theoretically propose an [...] Read more.

Anisotropic materials provide a new platform for building diverse polarization-dependent optical devices. Two-dimensional α-phase molybdenum trioxides (α-MoO₃), as newly emerging natural van der Waals materials, have attracted significant attention due to their unique anisotropy. In this work, we theoretically propose an anisotropic perfect metamaterial absorber in visible frequencies, the unit cell of which consists of a multi-layered α-MoO₃ nanoribbon/dielectric structure stacked on a silver substrate. Additionally, the number of perfect absorption bands is closely related to the α-MoO₃ nanoribbon/dielectric layers. When the proposed absorber is composed of three α-MoO₃ nanoribbon/dielectric layers, electromagnetic simulations show that triple-band perfect absorption can be achieved for polarization along [100], and [001] in the direction of, α-MoO₃, respectively. Moreover, the calculation results obtained by the finite-difference time-domain (FDTD) method are consistent with the effective impedance of the designed absorber. The physical mechanism of multi-band perfect absorption can be attributed to resonant grating modes and the interference effect of Fabry–Pérot cavity modes. In addition, the absorption spectra of the proposed structure, as a function of wavelength and the related geometrical parameters, have been calculated and analyzed in detail. Our proposed absorber may have potential applications in spectral imaging, photo-detectors, sensors, etc. Full article

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19 pages, 4467 KiB

Open AccessEditor’s ChoiceArticle

Minute-Made, High-Efficiency Nanostructured Bi₂Te₃ via High-Throughput Green Solution Chemical Synthesis

by Bejan Hamawandi, Hazal Batili, Moon Paul, Sedat Ballikaya, Nuzhet I. Kilic, Rafal Szukiewicz, Maciej Kuchowicz, Mats Johnsson and Muhammet S. Toprak

Nanomaterials 2021, 11(8), 2053; https://doi.org/10.3390/nano11082053 - 12 Aug 2021

Cited by 26 | Viewed by 5326

Abstract

Scalable synthetic strategies for high-quality and reproducible thermoelectric (TE) materials is an essential step for advancing the TE technology. We present here very rapid and effective methods for the synthesis of nanostructured bismuth telluride materials with promising TE performance. The methodology is based [...] Read more.

Scalable synthetic strategies for high-quality and reproducible thermoelectric (TE) materials is an essential step for advancing the TE technology. We present here very rapid and effective methods for the synthesis of nanostructured bismuth telluride materials with promising TE performance. The methodology is based on an effective volume heating using microwaves, leading to highly crystalline nanostructured powders, in a reaction duration of two minutes. As the solvents, we demonstrate that water with a high dielectric constant is as good a solvent as ethylene glycol (EG) for the synthetic process, providing a greener reaction media. Crystal structure, crystallinity, morphology, microstructure and surface chemistry of these materials were evaluated using XRD, SEM/TEM, XPS and zeta potential characterization techniques. Nanostructured particles with hexagonal platelet morphology were observed in both systems. Surfaces show various degrees of oxidation, and signatures of the precursors used. Thermoelectric transport properties were evaluated using electrical conductivity, Seebeck coefficient and thermal conductivity measurements to estimate the TE figure-of-merit, ZT. Low thermal conductivity values were obtained, mainly due to the increased density of boundaries via materials nanostructuring. The estimated ZT values of 0.8–0.9 was reached in the 300–375 K temperature range for the hydrothermally synthesized sample, while 0.9–1 was reached in the 425–525 K temperature range for the polyol (EG) sample. Considering the energy and time efficiency of the synthetic processes developed in this work, these are rather promising ZT values paving the way for a wider impact of these strategic materials with a minimum environmental impact. Full article

(This article belongs to the Special Issue Thermoelectric Properties of Nanomaterials)

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13 pages, 320 KiB

Open AccessEditor’s ChoiceReview

Advanced Oxidation Processes Coupled with Nanomaterials for Water Treatment

by Inês M. F. Cardoso, Rita M. F. Cardoso and Joaquim C. G. Esteves da Silva

Nanomaterials 2021, 11(8), 2045; https://doi.org/10.3390/nano11082045 - 11 Aug 2021

Cited by 78 | Viewed by 6017

Abstract

Water quality management will be a priority issue in the near future. Indeed, due to scarcity and/or contamination of the water, regulatory frameworks will be increasingly strict to reduce environmental impacts of wastewater and to allow water to be reused. Moreover, drinking water [...] Read more.

Water quality management will be a priority issue in the near future. Indeed, due to scarcity and/or contamination of the water, regulatory frameworks will be increasingly strict to reduce environmental impacts of wastewater and to allow water to be reused. Moreover, drinking water quality standards must be improved in order to account for the emerging pollutants that are being detected in tap water. These tasks can only be achieved if new improved and sustainable water treatment technologies are developed. Nanomaterials are improving the ongoing research on advanced oxidation processes (AOPs). This work reviews the most important AOPs, namely: persulfate, chlorine and NH₂Cl based processes, UV/H₂O₂, Fenton processes, ozone, and heterogeneous photocatalytic processes. A critical review of the current coupling of nanomaterials to some of these AOPs is presented. Besides the active role of the nanomaterials in the degradation of water contaminants/pollutants in the AOPs, the relevance of their adsorbent/absorbent function in these processes is also discussed. Full article

(This article belongs to the Special Issue Development of Nanomaterials for Advanced Oxidation Processes of Dye Degradation and Water Remediation)

22 pages, 6300 KiB

Open AccessEditor’s ChoiceArticle

Nanogold-Carried Graphene Oxide: Anti-Inflammation and Increased Differentiation Capacity of Mesenchymal Stem Cells

by Huey-Shan Hung, Mei-Lang Kung, Fang-Chung Chen, Yi-Chun Ke, Chiung-Chyi Shen, Yi-Chin Yang, Chang-Ming Tang, Chun-An Yeh, Hsien-Hsu Hsieh and Shan-hui Hsu

Nanomaterials 2021, 11(8), 2046; https://doi.org/10.3390/nano11082046 - 11 Aug 2021

Cited by 21 | Viewed by 4422

Abstract

Graphene-based nanocomposites such as graphene oxide (GO) and nanoparticle-decorated graphene with demonstrated excellent physicochemical properties have worthwhile applications in biomedicine and bioengineering such as tissue engineering. In this study, we fabricated gold nanoparticle-decorated GO (GO-Au) nanocomposites and characterized their physicochemical properties using UV-Vis [...] Read more.

Graphene-based nanocomposites such as graphene oxide (GO) and nanoparticle-decorated graphene with demonstrated excellent physicochemical properties have worthwhile applications in biomedicine and bioengineering such as tissue engineering. In this study, we fabricated gold nanoparticle-decorated GO (GO-Au) nanocomposites and characterized their physicochemical properties using UV-Vis absorption spectra, FTIR spectra, contact angle analyses, and free radical scavenging potential. Moreover, we investigated the potent applications of GO-Au nanocomposites on directing mesenchymal stem cells (MSCs) for tissue regeneration. We compared the efficacy of as-prepared GO-derived nanocomposites including GO, GO-Au, and GO-Au (×2) on the biocompatibility of MSCs, immune cell identification, anti-inflammatory effects, differentiation capacity, as well as animal immune compatibility. Our results showed that Au-deposited GO nanocomposites, especially GO-Au (×2), significantly exhibited increased cell viability of MSCs, had good anti-oxidative ability, sponged the immune response toward monocyte-macrophage transition, as well as inhibited the activity of platelets. Moreover, we also validated the superior efficacy of Au-deposited GO nanocomposites on the enhancement of cell motility and various MSCs-derived cell types of differentiation including neuron cells, adipocytes, osteocytes, and endothelial cells. Additionally, the lower induction of fibrotic formation, reduced M1 macrophage polarization, and higher induction of M2 macrophage, as well as promotion of the endothelialization, were also found in the Au-deposited GO nanocomposites implanted animal model. These results suggest that the Au-deposited GO nanocomposites have excellent immune compatibility and anti-inflammatory effects in vivo and in vitro. Altogether, our findings indicate that Au-decorated GO nanocomposites, especially GO-Au (×2), can be a potent nanocarrier for tissue engineering and an effective clinical strategy for anti-inflammation. Full article

(This article belongs to the Special Issue Nanocarriers and Drug Delivery)

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11 pages, 3556 KiB

Open AccessEditor’s ChoiceArticle

Three-Dimensional Au/Ag Nanoparticle/Crossed Carbon Nanotube SERS Substrate for the Detection of Mixed Toxic Molecules

by Haonan Wei, Zhisheng Peng, Cheng Yang, Yuan Tian, Lianfeng Sun, Gongtang Wang and Mei Liu

Nanomaterials 2021, 11(8), 2026; https://doi.org/10.3390/nano11082026 - 9 Aug 2021

Cited by 21 | Viewed by 3090

Abstract

Research on engineering “hotspots” in the field of surface-enhanced Raman scattering (SERS) is at the forefront of contributing to the best sensing indicators. Currently, there is still an urgent need to design a high-strength and large-scale electric field distribution method in order to [...] Read more.

Research on engineering “hotspots” in the field of surface-enhanced Raman scattering (SERS) is at the forefront of contributing to the best sensing indicators. Currently, there is still an urgent need to design a high-strength and large-scale electric field distribution method in order to obtain an ideal SERS sensor. Here, we designed a three-dimensional (3D) Au/Ag nanoparticle (NP)/crossed carbon nanotube film SERS substrate. The proposed structure formed by the simple preparation process can perfectly coordinate the interaction between the SERS substrates, lasers, and molecules. The denser “hotspots” can be induced and then distributed in holes enclosed by Au/AgNPs and the gaps between them. This process was verified by numerical simulations. The experimental results show that the proposed SERS substrate possesses an excellent sensitivity of 10⁻¹² M (rhodamine 6G (R6G)), an enhancement factor of 1.60 × 10⁹, and a good signal reproducibility (the relative standard deviation is ~6.03%). We further use a Au/AgNP/crossed CNT substrate to detect complex solutions composed of toxic molecules, which shows that our proposed SERS substrate has a wide range of application potentials, especially in food safety. Full article

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19 pages, 2331 KiB

Open AccessEditor’s ChoiceReview

The Contribution of NMR Spectroscopy in Understanding Perovskite Stabilization Phenomena

by Federica Aiello and Sofia Masi

Nanomaterials 2021, 11(8), 2024; https://doi.org/10.3390/nano11082024 - 8 Aug 2021

Cited by 14 | Viewed by 8374

Abstract

Although it has been exploited since the late 1900s to study hybrid perovskite materials, nuclear magnetic resonance (NMR) spectroscopy has only recently received extraordinary research attention in this field. This very powerful technique allows the study of the physico-chemical and structural properties of [...] Read more.

Although it has been exploited since the late 1900s to study hybrid perovskite materials, nuclear magnetic resonance (NMR) spectroscopy has only recently received extraordinary research attention in this field. This very powerful technique allows the study of the physico-chemical and structural properties of molecules by observing the quantum mechanical magnetic properties of an atomic nucleus, in solution as well as in solid state. Its versatility makes it a promising technique either for the atomic and molecular characterization of perovskite precursors in colloidal solution or for the study of the geometry and phase transitions of the obtained perovskite crystals, commonly used as a reference material compared with thin films prepared for applications in optoelectronic devices. This review will explore beyond the current focus on the stability of perovskites (3D in bulk and nanocrystals) investigated via NMR spectroscopy, in order to highlight the chemical flexibility of perovskites and the role of interactions for thermodynamic and moisture stabilization. The exceptional potential of the vast NMR tool set in perovskite structural characterization will be discussed, aimed at choosing the most stable material for optoelectronic applications. The concept of a double-sided characterization in solution and in solid state, in which the organic and inorganic structural components provide unique interactions with each other and with the external components (solvents, additives, etc.), for material solutions processed in thin films, denotes a significant contemporary target. Full article

(This article belongs to the Special Issue Stable Perovskite Materials: From Synthesis to Optoelectronic Devices)

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16 pages, 4554 KiB

Open AccessEditor’s ChoiceArticle

Optimization of α-Fe₂O₃ Nanopillars Diameters for Photoelectrochemical Enhancement of α-Fe₂O₃-TiO₂ Heterojunction

by Herme G. Baldovi

Nanomaterials 2021, 11(8), 2019; https://doi.org/10.3390/nano11082019 - 7 Aug 2021

Cited by 12 | Viewed by 3249

Abstract

Global warming is pushing the world to seek to green energy sources and hydrogen is a good candidate to substitute fossil fuels in the short term. In future, it is expected that production of hydrogen will be carried out through photo-electrocatalysis. In this [...] Read more.

Global warming is pushing the world to seek to green energy sources and hydrogen is a good candidate to substitute fossil fuels in the short term. In future, it is expected that production of hydrogen will be carried out through photo-electrocatalysis. In this way, suitable electrodes that acts as photoanode absorbing the incident light are needed to catalyse water splitting reaction. Hematite (α-Fe₂O₃) is one of the most attractive semiconductors for this purpose since it is a low-cost material and it has a suitable band gap of 2.1 eV, which allows the absorption of the visible region. Although, hematite has drawbacks such as low carrier mobility and short holes diffusion lengths, that here it has been tried to overcome by nanoengineering the material, and by using a semiconductor as a scaffold that enhances charge carrier separation processes in the electrode. In this work, we fabricate ultrathin quasi transparent electrodes composed by highly ordered and self-standing hematite nanopillars of a few tens of nanometers length on FTO and TiO₂ supports. Photoanodes were fabricated utilizing electron beam evaporation technique and anodized aluminum oxide templates with well-defined pores diameters. Thus, the activity of the compact layer hematite photoanode is compared with the photoanodes fabricated with nanopillars of controllable diameters (i.e., 90, 260 and 400 nm) to study their influence on charge separation processes. Results indicated that optimal α-Fe₂O₃ photoanodes performance are obtained when nanopillars reach hundreds of nanometers in diameter, achieving for photoanodes with 400 nm nanopillars onto TiO₂ supports the highest photocurrent density values. Full article

(This article belongs to the Special Issue Nanoparticles and Nanostructures for Sustainable Heterogeneous Catalysis and Electrocatalysis)

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10 pages, 1911 KiB

Open AccessEditor’s ChoiceArticle

Optimizing the PMMA Electron-Blocking Layer of Quantum Dot Light-Emitting Diodes

by Mariya Zvaigzne, Alexei Alexandrov, Anastasia Tkach, Dmitriy Lypenko, Igor Nabiev and Pavel Samokhvalov

Nanomaterials 2021, 11(8), 2014; https://doi.org/10.3390/nano11082014 - 6 Aug 2021

Cited by 12 | Viewed by 4202

Abstract

Quantum dots (QDs) are promising candidates for producing bright, color-pure, cost-efficient, and long-lasting QD-based light-emitting diodes (QDLEDs). However, one of the significant problems in achieving high efficiency of QDLEDs is the imbalance between the rates of charge-carrier injection into the emissive QD layer [...] Read more.

Quantum dots (QDs) are promising candidates for producing bright, color-pure, cost-efficient, and long-lasting QD-based light-emitting diodes (QDLEDs). However, one of the significant problems in achieving high efficiency of QDLEDs is the imbalance between the rates of charge-carrier injection into the emissive QD layer and their transport through the device components. Here we investigated the effect of the parameters of the deposition of a poly (methyl methacrylate) (PMMA) electron-blocking layer (EBL), such as PMMA solution concentration, on the characteristics of EBL-enhanced QDLEDs. A series of devices was fabricated with the PMMA layer formed from acetone solutions with concentrations ranging from 0.05 to 1.2 mg/mL. The addition of the PMMA layer allowed for an increase of the maximum luminance of QDLED by a factor of four compared to the control device without EBL, that is, to 18,671 cd/m², with the current efficiency increased by an order of magnitude and the turn-on voltage decreased by ~1 V. At the same time, we have demonstrated that each particular QDLED characteristic has a maximum at a specific PMMA layer thickness; therefore, variation of the EBL deposition conditions could serve as an additional parameter space when other QDLED optimization approaches are being developed or implied in future solid-state lighting and display devices. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Optoelectronics and Photocatalysis)

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11 pages, 1716 KiB

Open AccessEditor’s ChoiceArticle

Stand-Alone CuFeSe₂ (Eskebornite) Nanosheets for Photothermal Cancer Therapy

by Mimi Liu, Daniela R. Radu, Gurpreet Singh Selopal, Saiphaneendra Bachu and Cheng-Yu Lai

Nanomaterials 2021, 11(8), 2008; https://doi.org/10.3390/nano11082008 - 5 Aug 2021

Cited by 13 | Viewed by 5528

Abstract

Two-dimensional CuFeSe₂ nanosheets have been successfully obtained via solution-phase synthesis using a sacrificial template method. The high purity was confirmed by X-ray diffraction and the two-dimensional morphology was validated by transmission electron microscopy. The intense absorption in the 400–1400 nm region has [...] Read more.

Two-dimensional CuFeSe₂ nanosheets have been successfully obtained via solution-phase synthesis using a sacrificial template method. The high purity was confirmed by X-ray diffraction and the two-dimensional morphology was validated by transmission electron microscopy. The intense absorption in the 400–1400 nm region has been the basis for the CuFeSe₂ nanosheets’ photothermal capabilities testing. The colloidal CuFeSe₂ (CFS) nanosheets capped with S²⁻ short ligands (CFS-S) exhibit excellent biocompatibility in cell culture studies and strong photothermal effects upon 808 nm laser irradiation. The nanosheets were further loaded with the cancer drug doxorubicin and exposed to laser irradiation, which accelerated the release of doxorubicin, achieving synergy in the therapeutic effect. Full article

(This article belongs to the Special Issue Multi-Functional Nanoparticles for Therapy and Diagnostics)

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40 pages, 7120 KiB

Open AccessEditor’s ChoiceReview

A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

by Adrià Garcia-Gil, Subhajit Biswas and Justin D. Holmes

Nanomaterials 2021, 11(8), 2002; https://doi.org/10.3390/nano11082002 - 4 Aug 2021

Cited by 11 | Viewed by 5493

Abstract

Ge nanowires are playing a big role in the development of new functional microelectronic modules, such as gate-all-around field-effect transistor devices, on-chip lasers and photodetectors. The widely used three-phase bottom-up growth method utilising a foreign catalyst metal or metalloid is by far the [...] Read more.

Ge nanowires are playing a big role in the development of new functional microelectronic modules, such as gate-all-around field-effect transistor devices, on-chip lasers and photodetectors. The widely used three-phase bottom-up growth method utilising a foreign catalyst metal or metalloid is by far the most popular for Ge nanowire growth. However, to fully utilise the potential of Ge nanowires, it is important to explore and understand alternative and functional growth paradigms such as self-seeded nanowire growth, where nanowire growth is usually directed by the in situ-formed catalysts of the growth material, i.e., Ge in this case. Additionally, it is important to understand how the self-seeded nanowires can benefit the device application of nanomaterials as the additional metal seeding can influence electron and phonon transport, and the electronic band structure in the nanomaterials. Here, we review recent advances in the growth and application of self-seeded Ge and Ge-based binary alloy (GeSn) nanowires. Different fabrication methods for growing self-seeded Ge nanowires are delineated and correlated with metal seeded growth. This review also highlights the requirement and advantage of self-seeded growth approach for Ge nanomaterials in the potential applications in energy storage and nanoelectronic devices. Full article

(This article belongs to the Special Issue Perspectives and New Horizons of Nanowires: From Synthesis to Applications)

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13 pages, 2572 KiB

Open AccessEditor’s ChoiceArticle

Poly(methacrylic Acid)-Cellulose Brushes as Anticancer Porphyrazine Carrier

by Elena L. Krasnopeeva, Elena Yu. Melenevskaya, Larisa G. Klapshina, Natalia Yu. Shilyagina, Irina V. Balalaeva, Nikolay N. Smirnov, Michael A. Smirnov and Alexander V. Yakimansky

Nanomaterials 2021, 11(8), 1997; https://doi.org/10.3390/nano11081997 - 3 Aug 2021

Cited by 12 | Viewed by 2866

Abstract

The prospective strategy for treatment of cancer is based on the application of nano-sized macromolecular carriers, which are able penetrate inside and can be accumulated within tumor tissue. In this work graft copolymers of cellulose and poly(methacrylic acid) has been prepared and tested [...] Read more.

The prospective strategy for treatment of cancer is based on the application of nano-sized macromolecular carriers, which are able penetrate inside and can be accumulated within tumor tissue. In this work graft copolymers of cellulose and poly(methacrylic acid) has been prepared and tested as a nanocontainers for the delivery of drug to tumor. For this purpose, two derivatives of porphyrazine suitable for photodynamic cancer therapy were loaded into prepared polymer brush. Fluorescence imaging was applied for monitoring of accumulation of porphyrazine in the CT26 murine colon carcinoma. The selective accumulation of cellulose brush loaded with porphyrazine in tumor was demonstrated by fluorescence intensity contrast between the tumor area and normal tissues. The tumor growth rate after photodynamic therapy were assessed and inhibition of its growth was revealed. Full article

(This article belongs to the Special Issue Cellulose Based Nanomaterials and Their Applications)

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12 pages, 5232 KiB

Open AccessEditor’s ChoiceArticle

Synthesis and Characterization of Tungsten Suboxide W_nO_3n−1 Nanotiles

by Luka Pirker, Bojana Višić, Janez Kovač, Srečo D. Škapin and Maja Remškar

Nanomaterials 2021, 11(8), 1985; https://doi.org/10.3390/nano11081985 - 2 Aug 2021

Cited by 5 | Viewed by 2728

Abstract

W_nO_3n−1 nanotiles, with multiple stoichiometries within one nanotile, were synthesized via the chemical vapour transport method. They grow along the [010] crystallographic axis, with the thickness ranging from a few tens to a few hundreds of nm, with the lateral [...] Read more.

W_nO_3n−1 nanotiles, with multiple stoichiometries within one nanotile, were synthesized via the chemical vapour transport method. They grow along the [010] crystallographic axis, with the thickness ranging from a few tens to a few hundreds of nm, with the lateral size up to several µm. Distinct surface corrugations, up to a few 10 nm deep appear during growth. The {102}_r crystallographic shear planes indicate the W_nO_3n−1 stoichiometries. Within a single nanotile, six stoichiometries were detected, namely W₁₆O₄₇ (WO_2.938), W₁₅O₄₄ (WO_2.933), W₁₄O₄₁ (WO_2.928), W₁₃O₃₈ (WO_2.923), W₁₂O₃₅ (WO_2.917), and W₁₁O₃₂ (WO_2.909), with the last three never being reported before. The existence of oxygen vacancies within the crystallographic shear planes resulted in the observed non-zero density of states at the Fermi energy. Full article

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10 pages, 3371 KiB

Open AccessEditor’s ChoiceArticle

Low-Power OR Logic Ferroelectric In-Situ Transistor Based on a CuInP₂S₆/MoS₂ Van Der Waals Heterojunction

by Kun Yang, Shulong Wang, Tao Han and Hongxia Liu

Nanomaterials 2021, 11(8), 1971; https://doi.org/10.3390/nano11081971 - 31 Jul 2021

Cited by 8 | Viewed by 4575

Abstract

Due to the limitations of thermodynamics, the Boltzmann distribution of electrons hinders the further reduction of the power consumption of field-effect transistors. However, with the emergence of ferroelectric materials, this problem is expected to be solved. Herein, we demonstrate an OR logic ferroelectric [...] Read more.

Due to the limitations of thermodynamics, the Boltzmann distribution of electrons hinders the further reduction of the power consumption of field-effect transistors. However, with the emergence of ferroelectric materials, this problem is expected to be solved. Herein, we demonstrate an OR logic ferroelectric in-situ transistor based on a CIPS/MoS₂ Van der Waals heterojunction. Utilizing the electric field amplification of ferroelectric materials, the CIPS/MoS₂ vdW ferroelectric transistor offers an average subthreshold swing (SS) of 52 mV/dec over three orders of magnitude, and a minimum SS of 40 mV/dec, which breaks the Boltzmann limit at room temperature. The dual-gated ferroelectric in-situ transistor exhibits excellent OR logic operation with a supply voltage of less than 1 V. The results indicate that the CIPS/MoS₂ vdW ferroelectric transistor has great potential in ultra-low-power applications due to its in-situ construction, steep-slope subthreshold swing and low supply voltage. Full article

(This article belongs to the Special Issue 2D Semiconducting Materials for Device Applications)

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24 pages, 18293 KiB

Open AccessEditor’s ChoiceArticle

Comparative Evaluation on Impacts of Fibronectin, Heparin–Chitosan, and Albumin Coating of Bacterial Nanocellulose Small-Diameter Vascular Grafts on Endothelialization In Vitro

by Max Wacker, Jan Riedel, Heike Walles, Maximilian Scherner, George Awad, Sam Varghese, Sebastian Schürlein, Bernd Garke, Priya Veluswamy, Jens Wippermann and Jörn Hülsmann

Nanomaterials 2021, 11(8), 1952; https://doi.org/10.3390/nano11081952 - 29 Jul 2021

Cited by 18 | Viewed by 4088

Abstract

In this study, we contrast the impacts of surface coating bacterial nanocellulose small-diameter vascular grafts (BNC-SDVGs) with human albumin, fibronectin, or heparin–chitosan upon endothelialization with human saphenous vein endothelial cells (VEC) or endothelial progenitor cells (EPC) in vitro. In one scenario, coated grafts [...] Read more.

In this study, we contrast the impacts of surface coating bacterial nanocellulose small-diameter vascular grafts (BNC-SDVGs) with human albumin, fibronectin, or heparin–chitosan upon endothelialization with human saphenous vein endothelial cells (VEC) or endothelial progenitor cells (EPC) in vitro. In one scenario, coated grafts were cut into 2D circular patches for static colonization of a defined inner surface area; in another scenario, they were mounted on a customized bioreactor and subsequently perfused for cell seeding. We evaluated the colonization by emerging metabolic activity and the preservation of endothelial functionality by water soluble tetrazolium salts (WST-1), acetylated low-density lipoprotein (AcLDL) uptake assays, and immune fluorescence staining. Uncoated BNC scaffolds served as controls. The fibronectin coating significantly promoted adhesion and growth of VECs and EPCs, while albumin only promoted adhesion of VECs, but here, the cells were functionally impaired as indicated by missing AcLDL uptake. The heparin–chitosan coating led to significantly improved adhesion of EPCs, but not VECs. In summary, both fibronectin and heparin–chitosan coatings could beneficially impact the endothelialization of BNC-SDVGs and might therefore represent promising approaches to help improve the longevity and reduce the thrombogenicity of BNC-SDVGs in the future. Full article

(This article belongs to the Special Issue Synthesis, Applications and Biological Impact of Nanocellulose)

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15 pages, 1965 KiB

Open AccessEditor’s ChoiceArticle

Environmental Hazards of Boron and Vanadium Nanoparticles in the Terrestrial Ecosystem—A Case Study with Enchytraeus crypticus

by Angela Barreto, Joana Santos, Mónica J. B. Amorim and Vera L. Maria

Nanomaterials 2021, 11(8), 1937; https://doi.org/10.3390/nano11081937 - 28 Jul 2021

Cited by 12 | Viewed by 2677

Abstract

From the start of the 21st century, nanoecotoxicological research has been growing in fast steps due to the need to evaluate the safety of the increasing use of engineered nanomaterials. Boron (B) and vanadium (V) nanoparticles (NPs) generated by anthropogenic activities are subsequently [...] Read more.

From the start of the 21st century, nanoecotoxicological research has been growing in fast steps due to the need to evaluate the safety of the increasing use of engineered nanomaterials. Boron (B) and vanadium (V) nanoparticles (NPs) generated by anthropogenic activities are subsequently released in the environment; therefore, organisms can be continuously exposed to these NPs for short or long periods. However, the short and long-term effects of BNPs and VNPs on soil organisms are unknown. This work aimed to recognize and describe their potential toxicological effects on the model species Enchytraeus crypticus, assessing survival and reproduction, through a longer-term exposure (56 days (d)—OECD test extension of 28 d), and avoidance behavior, through a short-term exposure (48 hours (h)). After 28 d, BNPs did not induce a significant effect on E. crypticus survival, whereas they decreased the organisms’ reproduction at 500 mg/kg. From 10 to 500 mg/kg, VNPs decreased the E. crypticus survival and/or reproduction. After 56 d, 100 to 500 mg/kg BNPs and 50 to 500 mg/kg VNPs, decreased the reproduction output of E. crypticus. The estimated Effect Concentrations (EC_x) based on reproduction, for BNPs, were lower at 56 d compared with 28 d; for VNPs, an opposite pattern was found: EC_x 28 d < EC_x 56 d. BNPs did not induce an avoidance behavior, but organisms avoided the soil contaminated with 10 mg VNPs/kg. The tested NPs showed different E. crypticus apical effects at 28 d from the ones detected at 56 d, dependent on the type of NPs (B vs. V). In general, VNPs showed to be more toxic than BNPs. However, the effects of VNPs were alleviated during the time of exposure, contrarily to BNPs (which became more toxic with extended duration). The present study adds important information about NPs toxicity with ecological significance (at the population level). Including long-term effects, the obtained results contributes to the improvement of NPs risk assessment. Full article

(This article belongs to the Special Issue Environmental Nanotechnology)

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20 pages, 2710 KiB

Open AccessEditor’s ChoiceArticle

Propane Steam Reforming over Catalysts Derived from Noble Metal (Ru, Rh)-Substituted LaNiO₃ and La_0.8Sr_0.2NiO₃ Perovskite Precursors

by Theodora Ramantani, Georgios Bampos, Andreas Vavatsikos, Georgios Vatskalis and Dimitris I. Kondarides

Nanomaterials 2021, 11(8), 1931; https://doi.org/10.3390/nano11081931 - 27 Jul 2021

Cited by 16 | Viewed by 4294

Abstract

The propane steam reforming (PSR) reaction was investigated over catalysts derived from LaNiO₃ (LN), La_0.8Sr_0.2NiO₃ (LSN), and noble metal-substituted LNM_x and LSNM_x (M = Ru, Rh; x = 0.01, 0.1) perovskites. The incorporation of foreign [...] Read more.

The propane steam reforming (PSR) reaction was investigated over catalysts derived from LaNiO₃ (LN), La_0.8Sr_0.2NiO₃ (LSN), and noble metal-substituted LNM_x and LSNM_x (M = Ru, Rh; x = 0.01, 0.1) perovskites. The incorporation of foreign cations in the A and/or B sites of the perovskite structure resulted in an increase in the specific surface area, a shift of XRD lines toward lower diffraction angles, and a decrease of the mean primary crystallite size of the parent material. Exposure of the as-prepared samples to reaction conditions resulted in the in situ development of new phases including metallic Ni and La₂O₂CO₃, which participate actively in the PSR reaction. The LN-derived catalyst exhibited higher activity compared to LSN, and its performance for the title reaction did not change appreciably following partial substitution of Ru for Ni. In contrast, incorporation of Ru and, especially, Rh in the LSN perovskite matrix resulted in the development of catalysts with significantly enhanced catalytic performance, which improved by increasing the noble metal content. The best results were obtained for the LSNRh_0.1-derived sample, which exhibited excellent long-term stability for 40 hours on stream as well as high propane conversion (X_C3H8 = 92%) and H₂ selectivity (S_H2 = 97%) at 600 °C. Full article

(This article belongs to the Special Issue 10th Anniversary of Nanomaterials—Recent Advances in Environmental Nanoscience and Nanotechnology)

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17 pages, 4504 KiB

Open AccessEditor’s ChoiceArticle

Influence of Drying Method and Argon Plasma Modification of Bacterial Nanocellulose on Keratinocyte Adhesion and Growth

by Anna Kutová, Lubica Staňková, Kristýna Vejvodová, Ondřej Kvítek, Barbora Vokatá, Dominik Fajstavr, Zdeňka Kolská, Antonín Brož, Lucie Bačáková and Václav Švorčík

Nanomaterials 2021, 11(8), 1916; https://doi.org/10.3390/nano11081916 - 26 Jul 2021

Cited by 17 | Viewed by 3251

Abstract

Due to its nanostructure, bacterial nanocellulose (BC) has several advantages over plant cellulose, but it exhibits weak cell adhesion. To overcome this drawback, we studied the drying method of BC and subsequent argon plasma modification (PM). BC hydrogels were prepared using the Komagataeibacter [...] Read more.

Due to its nanostructure, bacterial nanocellulose (BC) has several advantages over plant cellulose, but it exhibits weak cell adhesion. To overcome this drawback, we studied the drying method of BC and subsequent argon plasma modification (PM). BC hydrogels were prepared using the Komagataeibacter sucrofermentans (ATCC 700178) bacteria strain. The hydrogels were transformed into solid samples via air-drying (BC-AD) or lyophilization (BC-L). The sample surfaces were then modified by argon plasma. SEM revealed that compared to BC-AD, the BC-L samples maintained their nanostructure and had higher porosity. After PM, the contact angle decreased while the porosity increased. XPS showed that the O/C ratio was higher after PM. The cell culture experiments revealed that the initial adhesion of human keratinocytes (HaCaT) was supported better on BC-L, while the subsequent growth of these cells and final cell population density were higher on BC-AD. The PM improved the final colonization of both BC-L and BC-AD with HaCaT, leading to formation of continuous cell layers. Our work indicates that the surface modification of BC renders this material highly promising for skin tissue engineering and wound healing. Full article

(This article belongs to the Special Issue Advanced Nanocellulose-Based Materials: Production, Properties and Applications)

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13 pages, 11934 KiB

Open AccessEditor’s ChoiceArticle

Seedless Cu Electroplating on Co-W Thin Films in Low pH Electrolyte: Early Stages of Formation

by Rúben F. Santos, Bruno M. C. Oliveira, Alexandre Chícharo, Pedro Alpuim, Paulo J. Ferreira, Sónia Simões, Filomena Viana and Manuel F. Vieira

Nanomaterials 2021, 11(8), 1914; https://doi.org/10.3390/nano11081914 - 25 Jul 2021

Cited by 3 | Viewed by 3502

Abstract

The use of Ta/TaN barrier bilayer systems in electronic applications has been ubiquitous over the last decade. Alternative materials such as Co-W or Ru-W alloys have gathered interest as possible replacements due to their conjugation of favourable electrical properties and barrier layer efficiency [...] Read more.

The use of Ta/TaN barrier bilayer systems in electronic applications has been ubiquitous over the last decade. Alternative materials such as Co-W or Ru-W alloys have gathered interest as possible replacements due to their conjugation of favourable electrical properties and barrier layer efficiency at reduced thicknesses while enabling seedless Cu electroplating. The microstructure, morphology, and electrical properties of Cu films directly electrodeposited onto Co-W or Ru-W are important to assess, concomitant with their ability to withstand the electroplating baths/conditions. This work investigates the effects of the current application method and pH value of the electroplating solution on the electrocrystallisation behaviour of Cu deposited onto a Co-W barrier layer. The film structure, morphology, and chemical composition were studied by X-ray diffraction, scanning electron microscopy and atomic force microscopy, as well as photoelectron spectroscopy. The results show that the electrolyte solution at pH 1.8 is incapable of creating a compact Cu film over the Co-W layer in either pulsed or direct-current modes. At higher pH, a continuous film is formed. A mechanism is proposed for the nucleation and growth of Cu on Co-W, where a balance between Cu nucleation, growth, and preferential Co dissolution dictates the substrate area coverage and compactness of the electrodeposited films. Full article

(This article belongs to the Section Nanofabrication and Nanomanufacturing)

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11 pages, 12429 KiB

Open AccessEditor’s ChoiceArticle

Study of the Molecule Adsorption Process during the Molecular Doping

by Mattia Pizzone, Maria Grazia Grimaldi, Antonino La Magna, Neda Rahmani, Silvia Scalese, Jost Adam and Rosaria A. Puglisi

Nanomaterials 2021, 11(8), 1899; https://doi.org/10.3390/nano11081899 - 24 Jul 2021

Cited by 2 | Viewed by 2475

Abstract

Molecular Doping (MD) involves the deposition of molecules, containing the dopant atoms and dissolved in liquid solutions, over the surface of a semiconductor before the drive-in step. The control on the characteristics of the final doped samples resides on the in-depth study of [...] Read more.

Molecular Doping (MD) involves the deposition of molecules, containing the dopant atoms and dissolved in liquid solutions, over the surface of a semiconductor before the drive-in step. The control on the characteristics of the final doped samples resides on the in-depth study of the molecule behaviour once deposited. It is already known that the molecules form a self-assembled monolayer over the surface of the sample, but little is known about the role and behaviour of possible multiple layers that could be deposited on it after extended deposition times. In this work, we investigate the molecular surface coverage over time of diethyl-propyl phosphonate on silicon, by employing high-resolution morphological and electrical characterization, and examine the effects of the post-deposition surface treatments on it. We present these data together with density functional theory simulations of the molecules–substrate system and electrical measurements of the doped samples. The results allow us to recognise a difference in the bonding types involved in the formation of the molecular layers and how these influence the final doping profile of the samples. This will improve the control on the electrical properties of MD-based devices, allowing for a finer tuning of their performance. Full article

(This article belongs to the Section Nanofabrication and Nanomanufacturing)

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14 pages, 4834 KiB

Open AccessEditor’s ChoiceArticle

One-Step Electrodeposition Synthesized Aunps/Mxene/ERGO for Selectivity Nitrite Sensing

by Tan Wang, Cong Wang, Xianbao Xu, Zhen Li and Daoliang Li

Nanomaterials 2021, 11(8), 1892; https://doi.org/10.3390/nano11081892 - 23 Jul 2021

Cited by 23 | Viewed by 4033

Abstract

In this paper, a new nanocomposite AuNPs/MXene/ERGO was prepared for sensitive electrochemical detection of nitrite. The nanocomposite was prepared by a facile one-step electrodeposition, HAuCl4, GO and MXene mixed in PBS solution with the applied potential of −1.4 V for 600 s. The [...] Read more.

In this paper, a new nanocomposite AuNPs/MXene/ERGO was prepared for sensitive electrochemical detection of nitrite. The nanocomposite was prepared by a facile one-step electrodeposition, HAuCl4, GO and MXene mixed in PBS solution with the applied potential of −1.4 V for 600 s. The modified material was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and cyclic voltammetry (CV). The electrochemical behavior of nitrite at the modified electrode was performed by CV and chronoamperometry. The AuNPs/MXene/ERGO/GCE showed a well-defined oxidation peak for nitrite at +0.83 V (Vs. Ag/AgCl) in 0.1 M phosphate buffer solution (pH 7). The amperometric responses indicated the sensor had linear ranges of 0.5 to 80 μM and 80 to 780 μM with the LOD (0.15 μM and 0.015 μM) and sensitivity (340.14 and 977.89 μA mM⁻¹ cm⁻²), respectively. Moreover, the fabricated sensor also showed good selectivity, repeatability, and long-term stability with satisfactory recoveries for a real sample. We also propose the work that needs to be done in the future for material improvements in the conclusion. Full article

(This article belongs to the Special Issue Graphene-Based Nanomaterials)

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21 pages, 3662 KiB

Open AccessEditor’s ChoiceArticle

Electrically Conductive Networks from Hybrids of Carbon Nanotubes and Graphene Created by Laser Radiation

by Alexander Yu. Gerasimenko, Artem V. Kuksin, Yury P. Shaman, Evgeny P. Kitsyuk, Yulia O. Fedorova, Artem V. Sysa, Alexander A. Pavlov and Olga E. Glukhova

Nanomaterials 2021, 11(8), 1875; https://doi.org/10.3390/nano11081875 - 22 Jul 2021

Cited by 24 | Viewed by 4808

Abstract

A technology for the formation of electrically conductive nanostructures from single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), and their hybrids with reduced graphene oxide (rGO) on Si substrate has been developed. Under the action of single pulses of laser irradiation, nanowelding of [...] Read more.

A technology for the formation of electrically conductive nanostructures from single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), and their hybrids with reduced graphene oxide (rGO) on Si substrate has been developed. Under the action of single pulses of laser irradiation, nanowelding of SWCNT and MWCNT nanotubes with graphene sheets was obtained. Dependences of electromagnetic wave absorption by films of short and long nanotubes with subnanometer and nanometer diameters on wavelength are calculated. It was determined from dependences that absorption maxima of various types of nanotubes are in the wavelength region of about 266 nm. It was found that contact between nanotube and graphene was formed in time up to 400 fs. Formation of networks of SWCNT/MWCNT and their hybrids with rGO at threshold energy densities of 0.3/0.5 J/cm² is shown. With an increase in energy density above the threshold value, formation of amorphous carbon nanoinclusions on the surface of nanotubes was demonstrated. For all films, except the MWCNT film, an increase in defectiveness after laser irradiation was obtained, which is associated with appearance of C–C bonds with neighboring nanotubes or graphene sheets. CNTs played the role of bridges connecting graphene sheets. Laser-synthesized hybrid nanostructures demonstrated the highest hardness compared to pure nanotubes. Maximum hardness (52.7 GPa) was obtained for MWCNT/rGO topology. Regularity of an increase in electrical conductivity of nanostructures after laser irradiation has been established for films made of all nanomaterials. Hybrid structures of nanotubes and graphene sheets have the highest electrical conductivity compared to networks of pure nanotubes. Maximum electrical conductivity was obtained for MWCNT/rGO hybrid structure (~22.6 kS/m). Networks of nanotubes and CNT/rGO hybrids can be used to form strong electrically conductive interconnections in nanoelectronics, as well as to create components for flexible electronics and bioelectronics, including intelligent wearable devices (IWDs). Full article

(This article belongs to the Special Issue Growth, Characterization and Applications of Nanotubes)

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11 pages, 3465 KiB

Open AccessEditor’s ChoiceArticle

Controllable Martensite Transformation and Strain-Controlled Fatigue Behavior of a Gradient Nanostructured Austenite Stainless Steel

by Yunbo Lei, Jiuling Xu and Zhenbo Wang

Nanomaterials 2021, 11(8), 1870; https://doi.org/10.3390/nano11081870 - 21 Jul 2021

Cited by 9 | Viewed by 2891

Abstract

Gradient nanostructured (GNS) surface layer with a controllable martensite fraction has been synthesized on 316L austenitic stainless steel by means of surface mechanical rolling treatment (SMRT) with temperature being controlled. The mean grain size is in the nanometer scale in the near-surface layer [...] Read more.

Gradient nanostructured (GNS) surface layer with a controllable martensite fraction has been synthesized on 316L austenitic stainless steel by means of surface mechanical rolling treatment (SMRT) with temperature being controlled. The mean grain size is in the nanometer scale in the near-surface layer and increases gradually with depth. In addition, the volume fraction of martensite decreases from ~85% to 0 in the near-surface layer while the SMRT temperature increases from room temperature to 175 °C. Fatigue experiments showed that the strain-controlled fatigue properties of the GNS samples are significantly enhanced at total strain amplitudes ≥0.5%, especially in those with a dual-phase surface layer of austenite and pre-formed martensite. Analyses on fatigue mechanisms illustrated that the GNS surface layer enhances the strength-ductility synergy and suppresses the formation of surface fatigue defects during fatigue. In addition, the dual-phase structure promotes the formation of martensite and stacking faults, further enhancing fatigue properties at high strain amplitudes. Full article

(This article belongs to the Special Issue Gradient Nanograined Materials)

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20 pages, 2048 KiB

Open AccessEditor’s ChoiceArticle

Impact of Physico-Chemical Properties of Cellulose Nanocrystal/Silver Nanoparticle Hybrid Suspensions on Their Biocidal and Toxicological Effects

by Dafne Musino, Julie Devcic, Cécile Lelong, Sylvie Luche, Camille Rivard, Bastien Dalzon, Gautier Landrot, Thierry Rabilloud and Isabelle Capron

Nanomaterials 2021, 11(7), 1862; https://doi.org/10.3390/nano11071862 - 20 Jul 2021

Cited by 16 | Viewed by 4519

Abstract

There is a demand for nanoparticles that are environmentally acceptable, but simultaneously efficient and low cost. We prepared silver nanoparticles (AgNPs) grafted on a native bio-based substrate (cellulose nanocrystals, CNCs) with high biocidal activity and no toxicological impact. AgNPs of 10 nm are [...] Read more.

There is a demand for nanoparticles that are environmentally acceptable, but simultaneously efficient and low cost. We prepared silver nanoparticles (AgNPs) grafted on a native bio-based substrate (cellulose nanocrystals, CNCs) with high biocidal activity and no toxicological impact. AgNPs of 10 nm are nucleated on CNCs in aqueous suspension with content from 0.4 to 24.7 wt%. XANES experiments show that varying the NaBH4/AgNO3 molar ratio affects the AgNP oxidation state, while maintaining an fcc structure. AgNPs transition from 10 nm spherical NPs to 300 nm triangular-shaped AgNPrisms induced by H₂O₂ post-treatment. The 48 h biocidal activity of the hybrid tested on B. Subtilis is intensified with the increase of AgNP content irrespective of the Ag⁺/Ag₀ ratio in AgNPs, while the AgNSphere−AgNPrism transition induces a significant reduction of biocidal activity. A very low minimum inhibitory concentration of 0.016 mg AgNP/mL is determined. A new long-term biocidal activity test (up to 168 h) proved efficiency favorable to the smaller AgNPs. Finally, it is shown that AgNPs have no impact on the phagocytic capacity of mammalian cells. Full article

(This article belongs to the Section Biology and Medicines)

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12 pages, 5362 KiB

Open AccessEditor’s ChoiceArticle

Optical Studies and Transmission Electron Microscopy of HgCdTe Quantum Well Heterostructures for Very Long Wavelength Lasers

by Vladimir V. Rumyantsev, Anna A. Razova, Leonid S. Bovkun, Dmitriy A. Tatarskiy, Vladimir Y. Mikhailovskii, Maksim S. Zholudev, Anton V. Ikonnikov, Tatyana A. Uaman Svetikova, Kirill V. Maremyanin, Vladimir V. Utochkin, Mikhail A. Fadeev, Vladimir G. Remesnik, Vladimir Y. Aleshkin, Nikolay N. Mikhailov, Sergey A. Dvoretsky, Marek Potemski, Milan Orlita, Vladimir I. Gavrilenko and Sergey V. Morozov

Nanomaterials 2021, 11(7), 1855; https://doi.org/10.3390/nano11071855 - 19 Jul 2021

Cited by 8 | Viewed by 3169

Abstract

HgTe/CdHgTe quantum well (QW) heterostructures have attracted a lot of interest recently due to insights they provided towards the physics of topological insulators and massless Dirac fermions. Our work focuses on HgCdTe QWs with the energy spectrum close to the graphene-like relativistic dispersion [...] Read more.

HgTe/CdHgTe quantum well (QW) heterostructures have attracted a lot of interest recently due to insights they provided towards the physics of topological insulators and massless Dirac fermions. Our work focuses on HgCdTe QWs with the energy spectrum close to the graphene-like relativistic dispersion that is supposed to suppress the non-radiative Auger recombination. We combine various methods such as photoconductivity, photoluminescence and magneto-optical measurements as well as transmission electron microscopy to retrofit growth parameters in multi-QW waveguide structures, designed for long wavelengths lasing in the range of 10–22 μm. The results reveal that the attainable operating temperatures and wavelengths are strongly dependent on Cd content in the QW, since it alters the dominating recombination mechanism of the carriers. Full article

(This article belongs to the Special Issue Semiconductor Hetero-Nanostructures for Opto-Electronics Applications)

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11 pages, 2940 KiB

Open AccessEditor’s ChoiceArticle

Polarization and Dielectric Properties of BiFeO₃-BaTiO₃ Superlattice-Structured Ferroelectric Films

by Yuji Noguchi and Hiroki Matsuo

Nanomaterials 2021, 11(7), 1857; https://doi.org/10.3390/nano11071857 - 19 Jul 2021

Cited by 11 | Viewed by 5315

Abstract

Superlattice-structured epitaxial thin films composed of Mn(5%)-doped BiFeO₃ and BaTiO₃ with a total thickness of 600 perovskite (ABO₃) unit cells were grown on single-crystal SrTiO₃ substrates by pulsed laser deposition, and their polarization and dielectric properties were investigated. [...] Read more.

Superlattice-structured epitaxial thin films composed of Mn(5%)-doped BiFeO₃ and BaTiO₃ with a total thickness of 600 perovskite (ABO₃) unit cells were grown on single-crystal SrTiO₃ substrates by pulsed laser deposition, and their polarization and dielectric properties were investigated. When the layers of Mn-BiFeO₃ and BaTiO₃ have over 25 ABO₃ unit cells (N), the superlattice can be regarded as a simple series connection of their individual capacitors. The superlattices with an N of 5 or less behave as a unified ferroelectric, where the BaTiO₃ and Mn-BiFeO₃ layers are structurally and electronically coupled. Density functional theory calculations can explain the behavior of spontaneous polarization for the superlattices in this thin regime. We propose that a superlattice formation comprising two types of perovskite layers with different crystal symmetries opens a path to novel ferroelectrics that cannot be obtained in a solid solution system. Full article

(This article belongs to the Special Issue Pulsed Laser Deposition of Nanostructures, Thin Films and Multilayers)

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16 pages, 3034 KiB

Open AccessEditor’s ChoiceArticle

pH-Responsive Chitosan/Alginate Polyelectrolyte Complexes on Electrospun PLGA Nanofibers for Controlled Drug Release

by Jean Schoeller, Fabian Itel, Karin Wuertz-Kozak, Sandra Gaiser, Nicolas Luisier, Dirk Hegemann, Stephen J. Ferguson, Giuseppino Fortunato and René M. Rossi

Nanomaterials 2021, 11(7), 1850; https://doi.org/10.3390/nano11071850 - 17 Jul 2021

Cited by 55 | Viewed by 6794

Abstract

The surface functionalization of electrospun nanofibers allows for the introduction of additional functionalities while at the same time retaining the membrane properties of high porosity and surface-to-volume ratio. In this work, we sequentially deposited layers of chitosan and alginate to form a polyelectrolyte [...] Read more.

The surface functionalization of electrospun nanofibers allows for the introduction of additional functionalities while at the same time retaining the membrane properties of high porosity and surface-to-volume ratio. In this work, we sequentially deposited layers of chitosan and alginate to form a polyelectrolyte complex via layer-by-layer assembly on PLGA nanofibers to introduce pH-responsiveness for the controlled release of ibuprofen. The deposition of the polysaccharides on the surface of the fibers was revealed using spectroscopy techniques and ζ-potential measurements. The presence of polycationic chitosan resulted in a positive surface charge (16.2 ± 4.2 mV, pH 3.0) directly regulating the interactions between a model drug (ibuprofen) loaded within the polyelectrolyte complex and the layer-by-layer coating. The release of ibuprofen was slowed down in acidic pH (1.0) compared to neutral pH as a result of the interactions between the drug and the coating. The provided mesh acts as a promising candidate for the design of drug delivery systems required to bypass the acidic environment of the digestive tract. Full article

(This article belongs to the Special Issue Functionalization of Electrospun Nanofibers in Bioengineering)

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19 pages, 4746 KiB

Open AccessEditor’s ChoiceArticle

Characterization and Laser Structuring of Aqueous Processed Li(Ni_0.6Mn_0.2Co_0.2)O₂ Thick-Film Cathodes for Lithium-Ion Batteries

by Penghui Zhu, Jiahao Han and Wilhelm Pfleging

Nanomaterials 2021, 11(7), 1840; https://doi.org/10.3390/nano11071840 - 16 Jul 2021

Cited by 29 | Viewed by 4290

Abstract

Lithium-ion batteries have led the revolution in portable electronic devices and electrical vehicles due to their high gravimetric energy density. In particular, layered cathode material Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) can deliver high specific capacities of about 180 [...] Read more.

Lithium-ion batteries have led the revolution in portable electronic devices and electrical vehicles due to their high gravimetric energy density. In particular, layered cathode material Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) can deliver high specific capacities of about 180 mAh/g. However, traditional cathode manufacturing involves high processing costs and environmental issues due to the use of organic binder polyvinylidenfluoride (PVDF) and highly toxic solvent N-methyl-pyrrolidone (NMP). In order to overcome these drawbacks, aqueous processing of thick-film NMC 622 cathodes was studied using carboxymethyl cellulose and fluorine acrylic hybrid latex as binders. Acetic acid was added during the mixing process to obtain slurries with pH values varying from 7.4 to 12.1. The electrode films could be produced with high homogeneity using slurries with pH values smaller than 10. Cyclic voltammetry measurements showed that the addition of acetic acid did not affect the redox reaction of active material during charging and discharging. Rate capability tests revealed that the specific capacities with higher slurry pH values were increased at C-rates above C/5. Cells with laser structured thick-film electrodes showed an increase in capacity by 40 mAh/g in comparison to cells with unstructured electrodes. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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11 pages, 3725 KiB

Open AccessEditor’s ChoiceArticle

pH Sensitive Dextran Coated Fluorescent Nanodiamonds as a Biomarker for HeLa Cells Endocytic Pathway and Increased Cellular Uptake

by Linyan Nie, Yue Zhang, Lei Li, Patrick van Rijn and Romana Schirhagl

Nanomaterials 2021, 11(7), 1837; https://doi.org/10.3390/nano11071837 - 15 Jul 2021

Cited by 14 | Viewed by 4602

Abstract

Fluorescent nanodiamonds are a useful for biosensing of intracellular signaling networks or environmental changes (such as temperature, pH or free radical generation). HeLa cells are interesting to study with these nanodiamonds since they are a model cell system that is widely used to [...] Read more.

Fluorescent nanodiamonds are a useful for biosensing of intracellular signaling networks or environmental changes (such as temperature, pH or free radical generation). HeLa cells are interesting to study with these nanodiamonds since they are a model cell system that is widely used to study cancer-related diseases. However, they only internalize low numbers of nanodiamond particles very slowly via the endocytosis pathway. In this work, we show that pH-sensitive, dextran-coated fluorescent nanodiamonds can be used to visualise this pathway. Additionally, this coating improved diamond uptake in HeLa cells by 5.3 times (*** p < 0.0001) and decreased the required time for uptake to only 30 min. We demonstrated further that nanodiamonds enter HeLa cells via endolysosomes and are eventually expelled by cells. Full article

(This article belongs to the Section Biology and Medicines)

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12 pages, 4753 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Thermoelectric Performance of n-Type Bi₂Se₃ Nanosheets through Sn Doping

by Mengyao Li, Yu Zhang, Ting Zhang, Yong Zuo, Ke Xiao, Jordi Arbiol, Jordi Llorca, Yu Liu and Andreu Cabot

Nanomaterials 2021, 11(7), 1827; https://doi.org/10.3390/nano11071827 - 14 Jul 2021

Cited by 39 | Viewed by 4192

Abstract

The cost-effective conversion of low-grade heat into electricity using thermoelectric devices requires developing alternative materials and material processing technologies able to reduce the currently high device manufacturing costs. In this direction, thermoelectric materials that do not rely on rare or toxic elements such [...] Read more.

The cost-effective conversion of low-grade heat into electricity using thermoelectric devices requires developing alternative materials and material processing technologies able to reduce the currently high device manufacturing costs. In this direction, thermoelectric materials that do not rely on rare or toxic elements such as tellurium or lead need to be produced using high-throughput technologies not involving high temperatures and long processes. Bi₂Se₃ is an obvious possible Te-free alternative to Bi₂Te₃ for ambient temperature thermoelectric applications, but its performance is still low for practical applications, and additional efforts toward finding proper dopants are required. Here, we report a scalable method to produce Bi₂Se₃ nanosheets at low synthesis temperatures. We studied the influence of different dopants on the thermoelectric properties of this material. Among the elements tested, we demonstrated that Sn doping resulted in the best performance. Sn incorporation resulted in a significant improvement to the Bi₂Se₃ Seebeck coefficient and a reduction in the thermal conductivity in the direction of the hot-press axis, resulting in an overall 60% improvement in the thermoelectric figure of merit of Bi₂Se₃. Full article

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12 pages, 2563 KiB

Open AccessEditor’s ChoiceArticle

Multifunctional Tannic Acid-Alendronate Nanocomplexes with Antioxidant, Anti-Inflammatory, and Osteogenic Potency

by Somang Choi, Han-Saem Jo, Heegyeong Song, Hak-Jun Kim, Jong-Keon Oh, Jae-Woo Cho, Kyeongsoon Park and Sung-Eun Kim

Nanomaterials 2021, 11(7), 1812; https://doi.org/10.3390/nano11071812 - 13 Jul 2021

Cited by 20 | Viewed by 3881

Abstract

In the current study, we fabricated tannic acid-alendronate (TA-ALN) nanocomplexes (NPXs) via self-assembly. These TA-ALNs were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and FT-IR spectroscopy. The TA-ALNs were evaluated for antioxidant, anti-inflammatory, and osteogenesis-accelerating abilities in osteoblast-like cells (MC3T3-E1 [...] Read more.

In the current study, we fabricated tannic acid-alendronate (TA-ALN) nanocomplexes (NPXs) via self-assembly. These TA-ALNs were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and FT-IR spectroscopy. The TA-ALNs were evaluated for antioxidant, anti-inflammatory, and osteogenesis-accelerating abilities in osteoblast-like cells (MC3T3-E1 cells). All TA-ALNs displayed nano-sized beads that were circular in form. Treatment with TA-ALN (1:0.1) efficiently removed reactive oxygen species in cells and protected osteoblast-like cells from toxic hydrogen peroxide conditions. Moreover, TA-ALN (1:0.1) could markedly decrease the mRNA levels of pro-inflammatory mediators in lipopolysaccharide-stimulated cells. Furthermore, cells treated with TA-ALN (1:1) exhibited not only significantly greater alkaline phosphatase activity and calcium collection, but also outstandingly higher mRNA levels of osteogenesis-related elements such as collagen type I and osteocalcin. These outcomes indicate that the prepared TA-ALNs are excellent for antioxidant, anti-inflammatory, and osteogenic acceleration. Accordingly, TA-ALN can be used latently for bone renovation and regeneration in people with bone fractures, diseases, or disorders. Full article

(This article belongs to the Special Issue Drug Delivery Applications of Nanomaterials for Bone Diseases and Bone Regeneration)

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18 pages, 5493 KiB

Open AccessEditor’s ChoiceArticle

Advanced Large-Scale Nanofabrication Route for Ultrasensitive SERS Platforms Based on Precisely Shaped Gold Nanostructures

by Suzanna Akil, Rana Omar, Dmitry Kuznetsov, Vladimir Shur, Aotmane En Naciri and Safi Jradi

Nanomaterials 2021, 11(7), 1806; https://doi.org/10.3390/nano11071806 - 12 Jul 2021

Cited by 6 | Viewed by 2888

Abstract

One of the key issues for SERS-based trace applications is engineering structurally uniform substrates with ultrasensitivity, stability, and good reproducibility. A label-free, cost-effective, and reproducible fabrication strategy of ultrasensitive SERS sensors was reported in this work. Herein, we present recent progress in self-assembly-based [...] Read more.

One of the key issues for SERS-based trace applications is engineering structurally uniform substrates with ultrasensitivity, stability, and good reproducibility. A label-free, cost-effective, and reproducible fabrication strategy of ultrasensitive SERS sensors was reported in this work. Herein, we present recent progress in self-assembly-based synthesis to elaborate precisely shaped and abundant gold nanoparticles in a large area. We demonstrated that shape control is driven by the selective adsorption of a cation (Na⁺, K⁺, and H⁺) on a single facet of gold nanocrystal seeds during the growth process. We studied SERS features as a function of morphology. Importantly, we found a correlation between the shape and experimental SERS enhancement factors. We observed a detection threshold of 10⁻²⁰ M of bipyridine ethylene (BPE), which matches the lowest value determined in literature for BPE until now. Such novel sensing finding could be very promising for diseases and pathogen detection and opens up an avenue toward predicting which other morphologies could offer improved sensitivity. Full article

(This article belongs to the Special Issue Nanostructures for Surfaces, Catalysis and Sensing)

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11 pages, 2753 KiB

Open AccessEditor’s ChoiceArticle

Optimizing the Properties of La_0.8Sr_0.2CrO₃ Thin Films through Post-Annealing for High-Temperature Sensing

by Dan Liu, Peng Shi, Yantao Liu, Yijun Zhang, Bian Tian and Wei Ren

Nanomaterials 2021, 11(7), 1802; https://doi.org/10.3390/nano11071802 - 11 Jul 2021

Cited by 7 | Viewed by 2546

Abstract

La_0.8Sr_0.2CrO₃ (0.2LSCO) thin films were prepared via the RF sputtering method to fabricate thin-film thermocouples (TFTCs), and post-annealing processes were employed to optimize their properties to sense high temperatures. The XRD patterns of the 0.2LSCO thin films showed [...] Read more.

La_0.8Sr_0.2CrO₃ (0.2LSCO) thin films were prepared via the RF sputtering method to fabricate thin-film thermocouples (TFTCs), and post-annealing processes were employed to optimize their properties to sense high temperatures. The XRD patterns of the 0.2LSCO thin films showed a pure phase, and their crystallinities increased with the post-annealing temperature from 800 °C to 1000 °C, while some impurity phases of Cr₂O₃ and SrCr₂O₇ were observed above 1000 °C. The surface images indicated that the grain size increased first and then decreased, and the maximum size was 0.71 μm at 1100 °C. The cross-sectional images showed that the thickness of the 0.2LSCO thin films decreased significantly above 1000 °C, which was mainly due to the evaporation of Sr²⁺ and Cr³⁺. At the same time, the maximum conductivity was achieved for the film annealed at 1000 °C, which was 6.25 × 10⁻² S/cm. When the thin films post-annealed at different temperatures were coupled with Pt reference electrodes to form TFTCs, the trend of output voltage to first increase and then decrease was observed, and the maximum average Seebeck coefficient of 167.8 µV/°C was obtained for the 0.2LSCO thin film post-annealed at 1100 °C. Through post-annealing optimization, the best post-annealing temperature was 1000 °C, which made the 0.2LSCO thin film more stable to monitor the temperatures of turbine engines for a long period of time. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

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15 pages, 4677 KiB

Open AccessEditor’s ChoiceArticle

Trivalent Cations Detection of Magnetic-Sensitive Microcapsules by Controlled-Release Fluorescence Off-On Sensor

by Bo-Wei Du, Ching-Chang Lin and Fu-Hsiang Ko

Nanomaterials 2021, 11(7), 1801; https://doi.org/10.3390/nano11071801 - 10 Jul 2021

Cited by 2 | Viewed by 3361

Abstract

A pyrene-based derivative, 2-((pyrene-1-ylmethylene)amino)ethanol (PE) nanoparticle, was encapsulated via water-in-oil-in-water (W/O/W) double emulsion with the solvent evaporation method by one-pot reaction and utilized as a fluorescence turn-on sensor for detecting Fe³⁺, Cr³⁺, and Al³⁺ ions. Magnetic nanoparticles (MNPs) [...] Read more.

A pyrene-based derivative, 2-((pyrene-1-ylmethylene)amino)ethanol (PE) nanoparticle, was encapsulated via water-in-oil-in-water (W/O/W) double emulsion with the solvent evaporation method by one-pot reaction and utilized as a fluorescence turn-on sensor for detecting Fe³⁺, Cr³⁺, and Al³⁺ ions. Magnetic nanoparticles (MNPs) embedded in polycaprolactone (PCL) were used as the magnetic-sensitive polyelectrolyte microcapsule-triggered elements in the construction of the polymer matrix. The microcapsules were characterized by ultraviolet–visible (UV–Vis) and photoluminescence (PL) titrations, quantum yield (Φ_f) calculations, ¹H nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and superconducting quantum interference device magnetometry (SQUID) studies. This novel responsive release of the microcapsule fluorescence of the turn-on sensor for detecting trivalent cations was due to the compound PE and the MNPs being incorporated well within the whole system, and an effective thermal and kinetic energy transfer between the core and shell structure efficiently occurred in the externally oscillating magnetic field. The magnetic-sensitive fluorescence turn-on microcapsules show potential for effective metal ion sensing in environmental monitoring and even biomedical applications. Under the optimal controlled-release probe fluorescence conditions with high-frequency magnetic field treatment, the limit of detection (LOD) reached 1.574–2.860 μM and recoveries ranged from 94.7–99.4% for those metals in tap water. Full article

(This article belongs to the Special Issue Carbon-Based Nanomaterials and Sensor)

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