Nanomaterials

43 pages, 4139 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Advances in the Development of Lipid-, Metal-, Carbon-, and Polymer-Based Nanomaterials for Antibacterial Applications

by Ruohua Ren, Chiaxin Lim, Shiqi Li, Yajun Wang, Jiangning Song, Tsung-Wu Lin, Benjamin W. Muir, Hsien-Yi Hsu and Hsin-Hui Shen

Nanomaterials 2022, 12(21), 3855; https://doi.org/10.3390/nano12213855 - 1 Nov 2022

Cited by 38 | Viewed by 4815

Abstract

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to [...] Read more.

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to discover potential new antibiotics. The use of nanotechnology, encompassing a broad range of organic and inorganic nanomaterials, offers promising solutions. Organic nanomaterials, including lipid-, polymer-, and carbon-based nanomaterials, have inherent antibacterial activity or can act as nanocarriers in delivering antibacterial agents. Nanocarriers, owing to the protection and enhanced bioavailability of the encapsulated drugs, have the ability to enable an increased concentration of a drug to be delivered to an infected site and reduce the associated toxicity elsewhere. On the other hand, inorganic metal-based nanomaterials exhibit multivalent antibacterial mechanisms that combat MDR bacteria effectively and reduce the occurrence of bacterial resistance. These nanomaterials have great potential for the prevention and treatment of MDR bacterial infection. Recent advances in the field of nanotechnology are enabling researchers to utilize nanomaterial building blocks in intriguing ways to create multi-functional nanocomposite materials. These nanocomposite materials, formed by lipid-, polymer-, carbon-, and metal-based nanomaterial building blocks, have opened a new avenue for researchers due to the unprecedented physiochemical properties and enhanced antibacterial activities being observed when compared to their mono-constituent parts. This review covers the latest advances of nanotechnologies used in the design and development of nano- and nanocomposite materials to fight MDR bacteria with different purposes. Our aim is to discuss and summarize these recently established nanomaterials and the respective nanocomposites, their current application, and challenges for use in applications treating MDR bacteria. In addition, we discuss the prospects for antimicrobial nanomaterials and look forward to further develop these materials, emphasizing their potential for clinical translation. Full article

(This article belongs to the Special Issue Advanced Nanomaterials in Biomedical Application)

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7 pages, 2426 KiB

Open AccessEditor’s ChoiceReview

Role of Interdiffusion and Segregation during the Life of Indium Gallium Arsenide Quantum Dots, from Cradle to Grave

by Thomas Walther

Nanomaterials 2022, 12(21), 3850; https://doi.org/10.3390/nano12213850 - 31 Oct 2022

Cited by 4 | Viewed by 1854

Abstract

This article summarizes our understanding of the interplay between diffusion and segregation during epitaxial growth of InGaAs and InAs quantum dots. These quantum dots form spontaneously on flat GaAs (001) single-crystalline substrates by the so-called Stranski-Krastanow growth mechanism once a sufficient amount of [...] Read more.

This article summarizes our understanding of the interplay between diffusion and segregation during epitaxial growth of InGaAs and InAs quantum dots. These quantum dots form spontaneously on flat GaAs (001) single-crystalline substrates by the so-called Stranski-Krastanow growth mechanism once a sufficient amount of indium has accumulated on the surface. Initially a perfectly flat wetting layer is formed. This strained layer then starts to roughen as strain increases, leading first to small, long-range surface undulations and then to tiny coherent islands. These continue to grow, accumulating indium both from the underlying wetting layer by lateral indium segregation and from within these islands by vertical segregation, which for InGaAs deposition results in an indium-enriched InGaAs alloy in the centre of the quantum dots. For pure InAs deposition, interdiffusion also results in an InGaAs alloy. Further deposition can lead to the formation of misfit dislocations that nucleate at the edges of the islands and are generally sought to be avoided. Overgrowth by GaAs or InGaAs alloys with low indium content commences preferentially between the islands, avoiding their strained edges, which initially leads to trench formation. Further deposition is necessary to cap these quantum dots effectively and to re-gain an almost flat surface that can then be used for subsequent deposition of multiple layers of quantum dots as needed for many optoelectronic devices. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy for Nanomaterials Research Advances)

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10 pages, 3766 KiB

Open AccessEditor’s ChoiceArticle

Hot Electron Extraction in SWCNT/TiO₂ for Photocatalytic H₂ Evolution from Water

by Masahiro Yamagami, Tomoyuki Tajima, Zihao Zhang, Jun Kano, Ki-ichi Yashima, Takana Matsubayashi, Huyen Khanh Nguyen, Naoto Nishiyama, Tomoya Hayashi and Yutaka Takaguchi

Nanomaterials 2022, 12(21), 3826; https://doi.org/10.3390/nano12213826 - 29 Oct 2022

Cited by 4 | Viewed by 2618

Abstract

Single-walled carbon nanotube (SWCNT)/TiO₂ hybrids were synthesized using 1,10-bis(decyloxy)decane-core PAMAM dendrimer as a molecular glue. Upon photoirradiation of a water dispersion of SWCNT/TiO₂ hybrids with visible light (λ > 422 nm), the hydrogen evolution reaction proceeded at a rate of 0.95 [...] Read more.

Single-walled carbon nanotube (SWCNT)/TiO₂ hybrids were synthesized using 1,10-bis(decyloxy)decane-core PAMAM dendrimer as a molecular glue. Upon photoirradiation of a water dispersion of SWCNT/TiO₂ hybrids with visible light (λ > 422 nm), the hydrogen evolution reaction proceeded at a rate of 0.95 mmol/h·g in the presence of a sacrificial agent (1-benzyl-1,4-dihydronicotinamide, BNAH). External quantum yields (EQYs) of the hydrogen production reaction photosensitized by (6,5), (7,5), and (8,3) tubes were estimated to be 5.5%, 3.6%, and 2.2%, respectively, using monochromatic lights corresponding to their E₂₂ absorptions (570 nm, 650 nm, and 680 nm). This order of EQYs (i.e., (6,5) > (7,5) > (8,3)SWCNTs) exhibited the dependence on the C₂ energy level of SWCNT for EQY and proved the hot electron extraction pathway. Full article

(This article belongs to the Special Issue State-of-the-Art 2D and Carbon Nanomaterials in Japan)

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13 pages, 4181 KiB

Open AccessEditor’s ChoiceArticle

Fabrication of Cu Micromembrane as a Flexible Electrode

by Bo-Yao Sun, Wai-Hong Cheang, Shih-Cheng Chou, Jung-Chih Chiao and Pu-Wei Wu

Nanomaterials 2022, 12(21), 3829; https://doi.org/10.3390/nano12213829 - 29 Oct 2022

Cited by 1 | Viewed by 1909

Abstract

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and [...] Read more.

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and PEI provides adhesive, wetting, and reducing functionalities that facilitate subsequent Ag activation and Cu electroless plating. Scanning electron microscopy reveals conformal deposition of Cu on individual PP fibers. Porometer analysis indicates that the porous nature of PPMM is properly maintained. The Cu micromembrane demonstrates impressive electrical conductivities in both the X direction (1.04 ± 0.21 S/cm) and Z direction (2.99 ± 0.54 × 10⁻³ S/cm). In addition, its tensile strength and strain are better than those of pristine PPMM. The Cu micromembrane is flexible and mechanically robust enough to sustain 10,000 bending cycles with moderate deterioration. Thermogravimetric analysis shows a thermal stability of 400 °C and an effective Cu loading of 5.36 mg/cm². Cyclic voltammetric measurements reveal that the Cu micromembrane has an electrochemical surface area of 277.8 cm² in a 1 cm² geometric area (a roughness factor of 227.81), a value that is 45 times greater than that of planar Cu foil. Full article

(This article belongs to the Special Issue Latest Advances in Inorganic Nanomaterials)

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17 pages, 4229 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Hydrogen Production from Glycerol Aqueous Solutions as Sustainable Feedstocks Using Zr-Based UiO-66 Materials under Simulated Sunlight Irradiation

by Celia M. Rueda-Navarro, Belén Ferrer, Herme G. Baldoví and Sergio Navalón

Nanomaterials 2022, 12(21), 3808; https://doi.org/10.3390/nano12213808 - 28 Oct 2022

Cited by 15 | Viewed by 3247

Abstract

There is an increasing interest in developing cost-effective technologies to produce hydrogen from sustainable resources. Herein we show a comprehensive study on the use of metal–organic frameworks (MOFs) as heterogeneous photocatalysts for H₂ generation from photoreforming of glycerol aqueous solutions under simulated [...] Read more.

There is an increasing interest in developing cost-effective technologies to produce hydrogen from sustainable resources. Herein we show a comprehensive study on the use of metal–organic frameworks (MOFs) as heterogeneous photocatalysts for H₂ generation from photoreforming of glycerol aqueous solutions under simulated sunlight irradiation. The list of materials employed in this study include some of the benchmark Zr-MOFs such as UiO-66(Zr)-X (X: H, NO₂, NH₂) as well as MIL-125(Ti)-NH₂ as the reference Ti-MOF. Among these solids, UiO-66(Zr)-NH₂ exhibits the highest photocatalytic H₂ production, and this observation is attributed to its adequate energy level. The photocatalytic activity of UiO-66(Zr)-NH₂ can be increased by deposition of small Pt NPs as the reference noble metal co-catalyst within the MOF network. This photocatalyst is effectively used for H₂ generation at least for 70 h without loss of activity. The crystallinity of MOF and Pt particle size were maintained as revealed by powder X-ray diffraction and transmission electron microscopy measurements, respectively. Evidence in support of the occurrence of photoinduced charge separation with Pt@UiO-66(Zr)-NH₂ is provided from transient absorption and photoluminescence spectroscopies together with photocurrent measurements. This study exemplifies the possibility of using MOFs as photocatalysts for the solar-driven H₂ generation using sustainable feedstocks. Full article

(This article belongs to the Special Issue Carbon-Based Nanomaterials for Visible-Light Photocatalysis and Photoelectrocatalysis)

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23 pages, 6604 KiB

Open AccessEditor’s ChoiceArticle

Adsorption of Peptides onto Carbon Nanotubes Grafted with Poly(ethylene Oxide) Chains: A Molecular Dynamics Simulation Study

by Zuzana Benková, Peter Čakánek and Maria Natália D. S. Cordeiro

Nanomaterials 2022, 12(21), 3795; https://doi.org/10.3390/nano12213795 - 27 Oct 2022

Cited by 3 | Viewed by 1902

Abstract

Carbon nanotubes (CNTs) display exceptional properties that predispose them to wide use in technological or biomedical applications. To remove the toxicity of CNTs and to protect them against undesired protein adsorption, coverage of the CNT sidewall with poly(ethylene oxide) (PEO) is often considered. [...] Read more.

Carbon nanotubes (CNTs) display exceptional properties that predispose them to wide use in technological or biomedical applications. To remove the toxicity of CNTs and to protect them against undesired protein adsorption, coverage of the CNT sidewall with poly(ethylene oxide) (PEO) is often considered. However, controversial results on the antifouling effectiveness of PEO layers have been reported so far. In this work, the interactions of pristine CNT and CNT covered with the PEO chains at different grafting densities with polyglycine, polyserine, and polyvaline are studied using molecular dynamics simulations in vacuum, water, and saline environments. The peptides are adsorbed on CNT in all investigated systems; however, the adsorption strength is reduced in aqueous environments. Save for one case, addition of NaCl at a physiological concentration to water does not appreciably influence the adsorption and structure of the peptides or the grafted PEO layer. It turns out that the flexibility of the peptide backbone allows the peptide to adopt more asymmetric conformations which may be inserted deeper into the grafted PEO layer. Water molecules disrupt the internal hydrogen bonds in the peptides, as well as the hydrogen bonds formed between the peptides and the PEO chains. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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16 pages, 6096 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Investigation of Aerosol-Assisted Atmospheric Pressure Plasma Deposited Hybrid TiO₂ Containing Nanocomposite Coatings

by Chiara Lo Porto, Massimo Dell’Edera, Ilaria De Pasquale, Antonella Milella, Francesco Fracassi, Maria Lucia Curri, Roberto Comparelli and Fabio Palumbo

Nanomaterials 2022, 12(21), 3758; https://doi.org/10.3390/nano12213758 - 26 Oct 2022

Cited by 4 | Viewed by 1889

Abstract

We report on the aerosol-assisted atmospheric-pressure plasma deposition onto a stainless-steel woven mesh of a thin nanocomposite coating based on TiO₂ nanoparticles hosted in a hybrid organic–inorganic matrix, starting from nanoparticles dispersed in a mixture of hexamethyldisiloxane and isopropyl alcohol. The stainless-steel [...] Read more.

We report on the aerosol-assisted atmospheric-pressure plasma deposition onto a stainless-steel woven mesh of a thin nanocomposite coating based on TiO₂ nanoparticles hosted in a hybrid organic–inorganic matrix, starting from nanoparticles dispersed in a mixture of hexamethyldisiloxane and isopropyl alcohol. The stainless-steel mesh was selected as an effective support for the possible future technological application of the coating for photocatalytically assisted water depollution. The prepared coatings were thoroughly investigated from the chemical and morphological points of view and were demonstrated to be photocatalytically active in the degradation of an organic molecule, used as a pollutant model, in water upon UV light irradiation. In order to optimize the photocatalytic performance, different approaches were investigated for the coating’s realization, namely (i) the control of the deposition time and (ii) the application of a postdeposition O₂ plasma treatment on the pristine coatings. Both strategies were found to be able to increase the photocatalytic activity, and, remarkably, their combination resulted in a further enhancement of the photoactivity. Indeed, the proposed combined approach allowed a three-fold increase in the kinetic constant of the degradation reaction of the model dye methylene blue with respect to the pristine coating. Interestingly, the chemical and morphological characterizations of all the prepared coatings were able to account for the enhancement of the photocatalytic performance. Indeed, the presence of the TiO₂ nanoparticles on the outmost surface of the film confirmed the accessibility of the photocatalytic sites in the nanocomposite and reasonably explained the enhanced photocatalytic performance. In addition, the sustained photoactivity (>5 cycles of use) of the nanocomposites was demonstrated. Full article

(This article belongs to the Special Issue Unconventional and Green Approaches for the Synthesis of Crystalline Inorganic Materials)

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14 pages, 2230 KiB

Open AccessEditor’s ChoiceArticle

On the Development of Nanocomposite Covalent Associative Networks Based on Polycaprolactone and Reduced Graphite Oxide

by Alberto Vallin, Daniele Battegazzore, Giacomo Damonte, Alberto Fina and Orietta Monticelli

Nanomaterials 2022, 12(21), 3744; https://doi.org/10.3390/nano12213744 - 25 Oct 2022

Cited by 7 | Viewed by 1869

Abstract

In this work, the development of nanocomposite systems based on reduced graphite oxide (rGO) was combined with the development of crosslinked materials characterized by dynamic covalent bonds, i.e., a covalent associative network, starting from ad-hoc synthesized hydroxyl terminated polycaprolactone (PCL-OH). The crosslinking reaction [...] Read more.

In this work, the development of nanocomposite systems based on reduced graphite oxide (rGO) was combined with the development of crosslinked materials characterized by dynamic covalent bonds, i.e., a covalent associative network, starting from ad-hoc synthesized hydroxyl terminated polycaprolactone (PCL-OH). The crosslinking reaction was carried out using methylenediphenyl diisocyanate (MDI) to create systems capable of bond exchanges via transesterification and transcarbamoylation reactions, in the presence of stannous octoate as a catalyst. The above materials were prepared at two different temperatures (120 and 200 °C) and two PCL-OH:MDI ratios. FT-IR measurements proved the formation of urethane bonds in all the prepared samples. Crosslinking was demonstrated by contacting the samples with a solvent capable of dissolving the star-shaped PCL. These tests showed a significant increase in the crosslinked fraction with increasing the temperature and the PCL-OH:MDI ratio. In order to evidence the effect of crosslinking on rGO dispersion and the final properties of the material, a nanocomposite sample was also prepared using a linear commercial PCL, with the nanofiller mixed under the same conditions used to develop the crosslinked systems. The dispersion of rGO, which was investigated using FE-SEM measurements, was similar in the different systems prepared, indicating that the crosslinking process had a minor effect on the dispersibility of the nanofiller. As far as the thermal properties are concerned, the DSC measurements of the prepared samples showed that the crosslinking leads to a decrease in the crystallinity of the polymer, a phenomenon which was particularly evident in the sample prepared at 200 °C with a PCL-OH: MDI ratio of 1:1.33 and was related to the decrease in the polymer chain mobility. Moreover, rGO was found to act as a nucleating agent and increase the crystallization temperature of the nanocomposite sample based on linear commercial PCL, while the contribution of rGO in the crosslinked nanocomposite samples was minor. Rheological measurements confirmed the crosslinking of the PCL-OH system which generates a solid-like behavior depending on the PCL-OH:MDI ratio used. The presence of rGO during crosslinking generated a further huge increase in the viscosity of the melt with a remarkable solid-like behavior, confirming a strong interaction between rGO and crosslinked PCL. Finally, the prepared nanocomposites exhibited self-healing and recyclability properties, thus meeting the requirements for sustainable materials. Full article

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15 pages, 3754 KiB

Open AccessEditor’s ChoiceArticle

Electrostatic and Environmental Control of the Trion Fine Structure in Transition Metal Dichalcogenide Monolayers

by Yaroslav V. Zhumagulov, Alexei Vagov, Dmitry R. Gulevich and Vasili Perebeinos

Nanomaterials 2022, 12(21), 3728; https://doi.org/10.3390/nano12213728 - 24 Oct 2022

Cited by 2 | Viewed by 2270

Abstract

Charged excitons or trions are essential for optical spectra in low-dimensional doped monolayers (ML) of transitional metal dichalcogenides (TMDC). Using a direct diagonalization of the three-body Hamiltonian, we calculate the low-lying trion states in four types of TMDC MLs as a function of [...] Read more.

Charged excitons or trions are essential for optical spectra in low-dimensional doped monolayers (ML) of transitional metal dichalcogenides (TMDC). Using a direct diagonalization of the three-body Hamiltonian, we calculate the low-lying trion states in four types of TMDC MLs as a function of doping and dielectric environment. We show that the fine structure of the trion is the result of the interplay between the spin-valley fine structure of the single-particle bands and the exchange interaction. We demonstrate that by variations of the doping and dielectric environment, the fine structure of the trion energy can be tuned, leading to anticrossing of the bright and dark states, with substantial implications for the optical spectra of the TMDC ML. Full article

(This article belongs to the Special Issue Recent Advances in Optical Spectroscopy of Layered Materials)

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19 pages, 7216 KiB

Open AccessEditor’s ChoiceArticle

Optical Force of Bessel Pincer Light-Sheets Beam on a Dielectric Sphere of Arbitrary Size

by Shu Zhang, Bing Wei, Qun Wei, Renxian Li, Shiguo Chen and Ningning Song

Nanomaterials 2022, 12(21), 3723; https://doi.org/10.3390/nano12213723 - 23 Oct 2022

Cited by 2 | Viewed by 1578

Abstract

In the framework of Generalized Lorenz–Mie theory (GLMT), based on the expansion results of electromagnetic field radiation components of Bessel pincer light sheets beam acting on dielectric particles of arbitrary size, the expression of radiation force components in a Cartesian coordinate system is [...] Read more.

In the framework of Generalized Lorenz–Mie theory (GLMT), based on the expansion results of electromagnetic field radiation components of Bessel pincer light sheets beam acting on dielectric particles of arbitrary size, the expression of radiation force components in a Cartesian coordinate system is obtained by using the Maxwell stress tensor method. On the one hand, the effects of the refractive index and the equivalent radius of spherical particles on the distribution of radiation force are discussed; On the other hand, the influence of beam scaling parameter and beam order of Bessel pincer light sheets beam on the distribution of radiation force are investigated. The results indicate that the changes of particle’s refractive index and effective radius only affect the distribution of radiation force. However, the beam scaling parameter and beam order of Bessel pincer light sheets beam have a very sharp impact on the convergence position, distribution range and bending degree far away from the wave source of the radiation force. Single-beam optical tweezers using the self-focusing and self-bending Bessel pincer light-sheets beam are crucial for applications such as single molecule biophysics, optical manipulation and particle separation/clearing. Full article

(This article belongs to the Special Issue Research of Photonics at the Nanometer Scale)

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9 pages, 1702 KiB

Open AccessEditor’s ChoiceArticle

Design of Reflective Polarization Rotator in Silicon Waveguide

by Li-Ying Liu, Hong-Chang Huang, Chu-Wen Chen, Fu-Li Hsiao, Yu-Chieh Cheng and Chii-Chang Chen

Nanomaterials 2022, 12(20), 3694; https://doi.org/10.3390/nano12203694 - 21 Oct 2022

Cited by 3 | Viewed by 2991

Abstract

In this work, we investigate theoretically the reflective polarization rotator in a silicon waveguide formed by periodically arranged rectangular air holes. The etched air holes generate the large birefringence for the waveguide. The effective refractive index of the non-etched waveguide is isotropic. The [...] Read more.

In this work, we investigate theoretically the reflective polarization rotator in a silicon waveguide formed by periodically arranged rectangular air holes. The etched air holes generate the large birefringence for the waveguide. The effective refractive index of the non-etched waveguide is isotropic. The structure can be regarded as a stack of alternating birefringent waveplates and isotropic material similar to the folded Šolc filter. The band structure of the stack of birefringent waveplates with isotropic background is calculated to confirm the fact that high reflection peaks in the reflection spectra of the waveguide result from the photonic bandgap. The polarization extinction ratio for the reflected light is 15.8 dB. The highest reflectivity of the device is 93.1%, and the device length is 9.21 μm. An ultra-wide operation bandwidth from 1450.3 to 1621.8 nm can be achieved. Full article

(This article belongs to the Special Issue Nanophotonics and Integrated Optics Devices)

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10 pages, 23224 KiB

Open AccessEditor’s ChoiceArticle

Biofilm Degradation by Seashell-Derived Calcium Hydroxide and Hydrogen Peroxide

by Yuuki Hata, Yuta Bouda, Sumiyo Hiruma, Hiromi Miyazaki and Shingo Nakamura

Nanomaterials 2022, 12(20), 3681; https://doi.org/10.3390/nano12203681 - 20 Oct 2022

Cited by 6 | Viewed by 2524

Abstract

Microbial cells and self-produced extracellular polymeric substances assembled to form biofilms that are difficult to remove from surfaces, causing problems in various fields. Seashell-derived calcium hydroxide, a sustainable inorganic material, has shown high bactericidal activity even for biofilms due to its alkalinity. However, [...] Read more.

Microbial cells and self-produced extracellular polymeric substances assembled to form biofilms that are difficult to remove from surfaces, causing problems in various fields. Seashell-derived calcium hydroxide, a sustainable inorganic material, has shown high bactericidal activity even for biofilms due to its alkalinity. However, its biofilm removal efficacy is relatively low. Herein, we report a biofilm degradation strategy that includes two environmentally friendly reagents: seashell-derived calcium hydroxide and hydrogen peroxide. A biofilm model of Escherichia coli was prepared in vitro, treated with calcium hydroxide–hydrogen peroxide solutions, and semi-quantified by the crystal violet stain method. The treatment significantly improved biofilm removal efficacy compared with treatments by calcium hydroxide alone and hydrogen peroxide alone. The mechanism was elucidated from calcium hydroxide–hydrogen peroxide solutions, which suggested that perhydroxyl anion and hydroxyl radical generated from hydrogen peroxide, as well as the alkalinity of calcium hydroxide, enhanced biofilm degradation. This study showed that concurrent use of other reagents, such as hydrogen peroxide, is a promising strategy for improving the biofilm degradation activity of seashell-derived calcium hydroxide and will contribute to developing efficient biofilm removal methods. Full article

(This article belongs to the Special Issue Nano Geochemistry: Risk Assessment and Green Environmental Applications)

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11 pages, 5258 KiB

Open AccessEditor’s ChoiceArticle

Laser-Induced Forward Transferred Optical Scattering Nanosilica for Transparent Displays

by Ruo-Zhou Li, Mingqing Yang, Lvjiu Guo, Ke Qu, Tong Jian, Ying Yu and Jing Yan

Nanomaterials 2022, 12(20), 3674; https://doi.org/10.3390/nano12203674 - 19 Oct 2022

Cited by 4 | Viewed by 2495

Abstract

Laser printing has become a promising alternative for large-scale fabrication of functional devices. Here, laser-induced forward transfer (LIFT) of nanosilica was successfully achieved using a lower-cost nanosecond laser with a center wavelength of 1064 nm. To enhance the light absorption of silica, a [...] Read more.

Laser printing has become a promising alternative for large-scale fabrication of functional devices. Here, laser-induced forward transfer (LIFT) of nanosilica was successfully achieved using a lower-cost nanosecond laser with a center wavelength of 1064 nm. To enhance the light absorption of silica, a small amount of graphene oxide (GO) was added to the fumed silica. Investigations were conducted to give an insight into the role of GO in the LIFT process. Pattern deposition was achieved with a minimum line width of 221 μm. The scattering can be tuned from ~2.5% to ~17.5% by changing the laser fluence. The patternable transparent display based on laser transferred nanosilica (LTNS) film was also demonstrated, showing its capability to deliver information on multiple levels. This LIFT based technique promotes fast, flexible, and low-cost manufacturing of scattering-based translucent screens or patterns for transparent displays. Full article

(This article belongs to the Special Issue Scalable Fabrication Techniques for Nanostructures and Nanomaterials Facing Cutting-Edge Applications in Electronics, Energy, and Environment)

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11 pages, 10475 KiB

Open AccessEditor’s ChoiceArticle

Electric-Field Control in Phosphorene-Based Heterostructures

by Calin-Andrei Pantis-Simut, Amanda Teodora Preda, Nicolae Filipoiu, Alaa Allosh and George Alexandru Nemnes

Nanomaterials 2022, 12(20), 3650; https://doi.org/10.3390/nano12203650 - 18 Oct 2022

Cited by 4 | Viewed by 2320

Abstract

Phosphorene is a graphene-like material with an intermediate band gap, in contrast to zero-gap graphene and large-gap dichalcogenides or hexagonal boron nitride (hBN), which makes it more suitable for nanoelectronic devices. However, inducing band-gap modulation in freestanding phosphorene nanoribbons (PNRs) is problematic, as [...] Read more.

Phosphorene is a graphene-like material with an intermediate band gap, in contrast to zero-gap graphene and large-gap dichalcogenides or hexagonal boron nitride (hBN), which makes it more suitable for nanoelectronic devices. However, inducing band-gap modulation in freestanding phosphorene nanoribbons (PNRs) is problematic, as high in-plane electric fields are necessary to close the gap. We perform here a detailed investigation concerning the substrate influence on the electric-field control exerted by an external gate, using the density functional theory–non-equilibrium Green’s functions (DFT-NEGF) framework. It is established that the interaction with a hexagonal boron nitride supporting layer significantly enhances the gap modulation. Furthermore, we address the issue of contacting the PNRs, by using conducting graphene nanoribbons embedded in the support hBN layer. Within this setup, a measurable spin polarization is achieved owing to the anti-ferromagnetic coupling between the edges of the graphene nanoribbons. Full article

(This article belongs to the Special Issue Applied Physics and Nanomaterials)

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11 pages, 2578 KiB

Open AccessEditor’s ChoiceArticle

B-Site Fe/Re Cation-Ordering Control and Its Influence on the Magnetic Properties of Sr₂FeReO₆ Oxide Powders

by Zhuowei Wang, Qingkai Tang, Zhiwei Wu, Kang Yi, Jiayuan Gu and Xinhua Zhu

Nanomaterials 2022, 12(20), 3640; https://doi.org/10.3390/nano12203640 - 17 Oct 2022

Cited by 4 | Viewed by 1901

Abstract

Double-perovskite oxide Sr₂FeReO₆ (SFRO) powders have promising applications in spintronics due to their half-metallicity and high Curie temperature. However, their magnetic properties suffer from the existence of anti-site defects (ASDs). Here, we report on the synthesis of SFRO powders by [...] Read more.

Double-perovskite oxide Sr₂FeReO₆ (SFRO) powders have promising applications in spintronics due to their half-metallicity and high Curie temperature. However, their magnetic properties suffer from the existence of anti-site defects (ASDs). Here, we report on the synthesis of SFRO powders by the sol–gel process. The B-site cationic ordering degree (η) and its influence on magnetic properties are investigated. The results demonstrate that the η value is well controlled by the annealing temperature, which is as high as 85% when annealing at 1100 °C. However, the annealing atmospheres (e.g., N₂ or Ar) have little effect on the η value. At room temperature, the SFRO powders crystallize in a tetragonal crystal structure (space group I4/m). They have a relatively uniform morphology and the molar ratios of Sr, Fe, and Re elements are close to 2:1:1. XPS spectra identified that Sr, Fe, and Re elements presented as Sr²⁺, Fe³⁺, and Re⁵⁺ ions, respectively, and the O element presented as O^2-. The SFRO samples annealed at 1100 °C in N₂, exhibiting the highest saturation magnetization (M_S = 2.61 μ_B/f.u. at 2 K), which was ascribed to their smallest ASD content (7.45%) with an anti-phase boundary-like morphology compared to those annealed at 1000 °C (ASDs = 10.7%) or 1200 °C (ASDs = 10.95%). Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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13 pages, 3248 KiB

Open AccessEditor’s ChoiceArticle

Transfer Learning for Modeling Plasmonic Nanowire Waveguides

by Aoning Luo, Yuanjia Feng, Chunyan Zhu, Yipei Wang and Xiaoqin Wu

Nanomaterials 2022, 12(20), 3624; https://doi.org/10.3390/nano12203624 - 16 Oct 2022

Cited by 3 | Viewed by 1841

Abstract

Retrieving waveguiding properties of plasmonic metal nanowires (MNWs) through numerical simulations is time- and computational-resource-consuming, especially for those with abrupt geometric features and broken symmetries. Deep learning provides an alternative approach but is challenging to use due to inadequate generalization performance and the [...] Read more.

Retrieving waveguiding properties of plasmonic metal nanowires (MNWs) through numerical simulations is time- and computational-resource-consuming, especially for those with abrupt geometric features and broken symmetries. Deep learning provides an alternative approach but is challenging to use due to inadequate generalization performance and the requirement of large sets of training data. Here, we overcome these constraints by proposing a transfer learning approach for modeling MNWs under the guidance of physics. We show that the basic knowledge of plasmon modes can first be learned from free-standing circular MNWs with computationally inexpensive data, and then reused to significantly improve performance in predicting waveguiding properties of MNWs with various complex configurations, enabling much smaller errors (~23–61% reduction), less trainable parameters (~42% reduction), and smaller sets of training data (~50–80% reduction) than direct learning. Compared to numerical simulations, our model reduces the computational time by five orders of magnitude. Compared to other non-deep learning methods, such as the circular-area-equivalence approach and the diagonal-circle approximation, our approach enables not only much higher accuracies, but also more comprehensive characterizations, offering an effective and efficient framework to investigate MNWs that may greatly facilitate the design of polaritonic components and devices. Full article

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19 pages, 4074 KiB

Open AccessEditor’s ChoiceArticle

The Complexity of Comparative Adsorption of C₆ Hydrocarbons (Benzene, Cyclohexane, n-Hexane) at Metal–Organic Frameworks

by Christian Jansen, Nabil Assahub, Alex Spieß, Jun Liang, Alexa Schmitz, Shanghua Xing, Serkan Gökpinar and Christoph Janiak

Nanomaterials 2022, 12(20), 3614; https://doi.org/10.3390/nano12203614 - 15 Oct 2022

Cited by 16 | Viewed by 3435

Abstract

The relatively stable MOFs Alfum, MIL-160, DUT-4, DUT-5, MIL-53-TDC, MIL-53, UiO-66, UiO-66-NH₂, UiO-66(F)₄, UiO-67, DUT-67, NH₂-MIL-125, MIL-125, MIL-101(Cr), ZIF-8, ZIF-11 and ZIF-7 were studied for their C₆ sorption properties. An understanding of the uptake of the [...] Read more.

The relatively stable MOFs Alfum, MIL-160, DUT-4, DUT-5, MIL-53-TDC, MIL-53, UiO-66, UiO-66-NH₂, UiO-66(F)₄, UiO-67, DUT-67, NH₂-MIL-125, MIL-125, MIL-101(Cr), ZIF-8, ZIF-11 and ZIF-7 were studied for their C₆ sorption properties. An understanding of the uptake of the larger C₆ molecules cannot simply be achieved with surface area and pore volume (from N₂ sorption) but involves the complex micropore structure of the MOF. The maximum adsorption capacity at p p₀⁻¹ = 0.9 was shown by DUT-4 for benzene, MIL-101(Cr) for cyclohexane and DUT-5 for n-hexane. In the low-pressure range from p p₀⁻¹ = 0.1 down to 0.05 the highest benzene uptake is given by DUT-5, DUT-67/UiO-67 and MIL-101(Cr), for cyclohexane and n-hexane by DUT-5, UiO-67 and MIL-101(Cr). The highest uptake capacity at p p₀⁻¹ = 0.02 was seen with MIL-53 for benzene, MIL-125 for cyclohexane and DUT-5 for n-hexane. DUT-5 and MIL-101(Cr) are the MOFs with the widest pore window openings/cross sections but the low-pressure uptake seems to be controlled by a complex combination of ligand and pore-size effect. IAST selectivities between the three binary mixtures show a finely tuned and difficult to predict interplay of pore window size with (critical) adsorptive size and possibly a role of electrostatics through functional groups such as NH₂. Full article

(This article belongs to the Special Issue Advanced Porous Nanomaterials: Synthesis, Properties, and Application)

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10 pages, 2196 KiB

Open AccessEditor’s ChoiceArticle

A Versatile Route for Synthesis of Metal Nanoalloys by Discharges at the Interface of Two Immiscible Liquids

by Ahmad Hamdan and Luc Stafford

Nanomaterials 2022, 12(20), 3603; https://doi.org/10.3390/nano12203603 - 14 Oct 2022

Cited by 6 | Viewed by 1562

Abstract

Discharge in liquid is a promising technique to produce nanomaterials by electrode erosion. Although its feasibility was demonstrated in many conditions, the production of nanoalloys by in-liquid discharges remains a challenge. Here, we show that spark discharge in liquid cyclohexane that is in [...] Read more.

Discharge in liquid is a promising technique to produce nanomaterials by electrode erosion. Although its feasibility was demonstrated in many conditions, the production of nanoalloys by in-liquid discharges remains a challenge. Here, we show that spark discharge in liquid cyclohexane that is in contact with conductive solution, made of a combination of Ni-nitrate and/or Fe-nitrate and/or Co-nitrate, is suitable to produce nanoalloys (<10 nm) of Ni-Fe, Ni-Co, Co-Fe, and Ni-Co-Fe. The nanoparticles are synthesized by the reduction of metal ions during discharge, and they are individually embedded in C-matrix; this latter originates from the decomposition of cyclohexane. The results open novel ways to produce a wide spectrum of nanoalloys; they are needed for many applications, such as in catalysis, plasmonic, and energy conversion. Full article

(This article belongs to the Special Issue Morphological Design and Synthesis of Nanoparticles)

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15 pages, 3648 KiB

Open AccessEditor’s ChoiceArticle

Surface-Enhanced Raman Spectroscopy Chips Based on Silver Coated Gold Nanostars

by Miriam Parmigiani, Benedetta Albini, Giovanni Pellegrini, Marco Genovesi, Lorenzo De Vita, Piersandro Pallavicini, Giacomo Dacarro, Pietro Galinetto and Angelo Taglietti

Nanomaterials 2022, 12(20), 3609; https://doi.org/10.3390/nano12203609 - 14 Oct 2022

Cited by 14 | Viewed by 4648

Abstract

Surface-enhanced Raman scattering (SERS) is becoming widely used as an analytical tool, and the search for stable and highly responsive SERS substrates able to give ultralow detection of pollutants is a current challenge. In this paper we boosted the SERS response of Gold [...] Read more.

Surface-enhanced Raman scattering (SERS) is becoming widely used as an analytical tool, and the search for stable and highly responsive SERS substrates able to give ultralow detection of pollutants is a current challenge. In this paper we boosted the SERS response of Gold nanostars (GNS) demonstrating that their coating with a layer of silver having a proper thickness produces a 7-fold increase in SERS signals. Glass supported monolayers of these GNS@Ag were then prepared using simple alcoxyliane chemistry, yielding efficient and reproducible SERS chips, which were tested for the detection of molecules representative of different classes of pollutants. Among them, norfloxacin was detected down to 3 ppb, which is one of the lowest limits of detection obtained with this technique for the analyte. Full article

(This article belongs to the Special Issue SERS/SERRS-Active Nanostructures and Nanocomposites)

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20 pages, 3275 KiB

Open AccessEditor’s ChoiceArticle

Multifunctional Loblolly Pine-Derived Superactivated Hydrochar: Effect of Hydrothermal Carbonization on Hydrogen and Electron Storage with Carbon Dioxide and Dye Removal

by Al Ibtida Sultana, Cadianne Chambers, Muzammil M. N. Ahmed, Pavithra Pathirathna and Toufiq Reza

Nanomaterials 2022, 12(20), 3575; https://doi.org/10.3390/nano12203575 - 12 Oct 2022

Cited by 12 | Viewed by 2667

Abstract

Pore modulation via hydrothermal carbonization (HTC) needs investigation due to its crucial effect on surface that influences its multirole utilization of such ultraporous sorbents in applications of energy storage- hydrogen and capacitive- as well as for pollutant abatement- carbon capture and dye removal. [...] Read more.

Pore modulation via hydrothermal carbonization (HTC) needs investigation due to its crucial effect on surface that influences its multirole utilization of such ultraporous sorbents in applications of energy storage- hydrogen and capacitive- as well as for pollutant abatement- carbon capture and dye removal. Hence, loblolly pine was hydrothermally carbonized followed by KOH activation to synthesize superactivated hydrochars (SAH). The resulting SAHs had specific surface area (SSA) 1462–1703 m²/g, total pore (TPV) and micropore volume (MPV) of 0.62–0.78 cm³/g and 0.33–0.49 cm³/g, respectively. The SAHs exhibit excellent multifunctional performance with remarkably high atmospheric CO₂ capture of 145.2 mg/g and high pressure cryogenic H₂ storage of 54.9 mg/g. The fabricated supercapacitor displayed substantial specific capacitance value of maximum 47.2 Fg⁻¹ at 1 A g⁻¹ in 6 M KOH and highest MB dye removal of 719.4 mg/g. Higher HTC temperature resulted in increased surface porosity as higher SSA, TPV benefitted H₂ storage and MB dye removal while superior MPV favored CO₂ capture. Moderate HTC temperature ensured higher mesopore-to-macropore volume ratio favoring electrochemical performance. Isotherm modelling of the adsorbates was compared using models: Langmuir, Freundlich, Langmuir- Freundlich and Temkin. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Storage)

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13 pages, 2208 KiB

Open AccessEditor’s ChoiceArticle

Elucidation of Strain-Dependent, Zinc Oxide Nanorod Response for Nanorod-Guided Fluorescence Intensity

by Johnson Truong, Andrew Stoner, Marion Ryan C. Sytu, T Rizana Tatlock, David H. Cho and Jong-in Hahm

Nanomaterials 2022, 12(20), 3558; https://doi.org/10.3390/nano12203558 - 11 Oct 2022

Cited by 3 | Viewed by 1886

Abstract

In this work, we examine how strain exerted on individual ZnO nanorods (NRs) can influence the fluorescence signals that are emitted from fluorophore molecules and subsequently coupled into and guided along the NR. We elucidate the relationships between the incremental levels of compressive [...] Read more.

In this work, we examine how strain exerted on individual ZnO nanorods (NRs) can influence the fluorescence signals that are emitted from fluorophore molecules and subsequently coupled into and guided along the NR. We elucidate the relationships between the incremental levels of compressive and tensile strain on the NRs and measured fluorescence intensity of a model fluorophore, rhodamine 6G (R6G), as a function of the position on the NRs. We reveal that compressive strain on the NRs leads to a decrease in the guided fluorescence signal, while tensile strain leads to an increase in the fluorescence intensity. Compared to an unstrained state, approximately 35% decrease (increase) in R6G fluorescence intensity was observed from ZnO NRs when they were under compressive strain of −14% (tensile strain of +10%). Further, our systematic acquisition of the incremental addition of uniaxial strain result in a linear relationship of the coupled fluorescence signal and the amount of applied strain. The degree of fluorescence intensification on nanorod ends (DoF), which is a quantitative indicator for the amount of R6G signals coupled into and waveguided to the NR ends compared to those on the main body, also exhibits a linear relationship with strain. These outcomes, in turn, demonstrate that strain alters the waveguiding capabilities of ZnO NRs in a predictable manner, which can be exploited to modulate and optimize fluorescence and other light signals emitted by a nearby source. Considering the wide utility of ZnO NRs in photonics, optoelectronics, and sensors, insights from our study may be highly valuable to effectively controlling and enhancing optical signals from chemical and biological analytes through strain. Full article

(This article belongs to the Special Issue One-Dimensional Nanostructures: Synthesis, Characterization and Applications)

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13 pages, 3286 KiB

Open AccessEditor’s ChoiceArticle

Significance of Hydroxyl Groups on the Optical Properties of ZnO Nanoparticles Combined with CNT and PEDOT:PSS

by Keshav Nagpal, Erwan Rauwel, Elias Estephan, Maria Rosario Soares and Protima Rauwel

Nanomaterials 2022, 12(19), 3546; https://doi.org/10.3390/nano12193546 - 10 Oct 2022

Cited by 13 | Viewed by 3370

Abstract

We report on the synthesis of ZnO nanoparticles and their hybrids consisting of carbon nanotubes (CNT) and polystyrene sulfonate (PEDOT:PSS). A non-aqueous sol–gel route along with hydrated and anhydrous acetate precursors were selected for their syntheses. Transmission electron microscopy (TEM) studies revealed their [...] Read more.

We report on the synthesis of ZnO nanoparticles and their hybrids consisting of carbon nanotubes (CNT) and polystyrene sulfonate (PEDOT:PSS). A non-aqueous sol–gel route along with hydrated and anhydrous acetate precursors were selected for their syntheses. Transmission electron microscopy (TEM) studies revealed their spherical shape with an average size of 5 nm. TEM also confirmed the successful synthesis of ZnO-CNT and ZnO-PEDOT:PSS hybrid nanocomposites. In fact, the choice of precursors has a direct influence on the chemical and optical properties of the ZnO-based nanomaterials. The ZnO nanoparticles prepared with anhydrous acetate precursor contained a high amount of oxygen vacancies, which tend to degrade the polymer macromolecule, as confirmed from X-ray photoelectron spectroscopy and Raman spectroscopy. Furthermore, a relative increase in hydroxyl functional groups in the ZnO-CNT samples was observed. These functional groups were instrumental in the successful decoration of CNT and in producing the defect-related photoluminescence emission in ZnO-CNT. Full article

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

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13 pages, 2937 KiB

Open AccessEditor’s ChoiceArticle

High-Efficiency Ion Enrichment inside Ultra-Short Carbon Nanotubes

by Yu Qiang, Xueliang Wang, Zhemian Ying, Yuying Zhou, Renduo Liu, Siyan Gao and Long Yan

Nanomaterials 2022, 12(19), 3528; https://doi.org/10.3390/nano12193528 - 9 Oct 2022

Cited by 3 | Viewed by 2463

Abstract

The ion-enrichment inside carbon nanotubes (CNTs) offers the possibility of applications in water purification, ion batteries, memory devices, supercapacitors, field emission and functional hybrid nanostructures. However, the low filling capacity of CNTs in salt solutions due to end caps and blockages remains a [...] Read more.

The ion-enrichment inside carbon nanotubes (CNTs) offers the possibility of applications in water purification, ion batteries, memory devices, supercapacitors, field emission and functional hybrid nanostructures. However, the low filling capacity of CNTs in salt solutions due to end caps and blockages remains a barrier to the practical use of such applications. In this study, we fabricated ultra-short CNTs that were free from end caps and blockages using ball milling and acid pickling. We then compared their ion-enrichment capacity with that of long CNTs. The results showed that the ion-enrichment capacity of ultra-short CNTs was much higher than that of long CNTs. Furthermore, a broad range of ions could be enriched in the ultra-short CNTs including alkali-metal ions (e.g., K⁺), alkaline-earth-metal ions (e.g., Ca²⁺) and heavy-metal ions (e.g., Pb²⁺). The ultra-short CNTs were much more unobstructed than the raw long CNTs, which was due to the increased orifice number per unit mass of CNTs and the decreased difficulty in removing the blockages in the middle section inside the CNTs. Under the hydrated-cation–π interactions, the ultra-short CNTs with few end caps and blockages could highly efficiently enrich ions. Full article

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16 pages, 4700 KiB

Open AccessEditor’s ChoiceArticle

Effect of Covalent Organic Frameworks Containing Different Groups on Properties of Sulfonated Poly(ether ether ketone) Matrix Proton Exchange Membranes

by Xiaoyu Meng, Yinan Lv, Lei Ding, Luman Peng, Qiwang Peng, Chuanbo Cong, Haimu Ye and Qiong Zhou

Nanomaterials 2022, 12(19), 3518; https://doi.org/10.3390/nano12193518 - 8 Oct 2022

Cited by 7 | Viewed by 2417

Abstract

The rich −SO₃H groups enable sulfonated poly (ether ether ketone) (SPEEK) to possess excellent proton conductivities in proton exchange membrane (PEM), but cause excessive water absorption, resulting in the decline of dimensional stability. It is a challenge to resolve the conflict [...] Read more.

The rich −SO₃H groups enable sulfonated poly (ether ether ketone) (SPEEK) to possess excellent proton conductivities in proton exchange membrane (PEM), but cause excessive water absorption, resulting in the decline of dimensional stability. It is a challenge to resolve the conflict between conductivity and stability. Owing to its unique structural designability, covalent organic frameworks (COFs) have been used to regulate the performances of PEMs. The authors propose the use of COFs with acidic and basic groups for meeting the requirements of proton conductivity and dimensional stability. Herein, COFs containing different groups (sulfoacid, pyridine, and both) were uniformly dispersed into the SPEEK matrix by in situ synthesis, and the effects on the properties of SPEEK matrix PEMs were revealed. The sulfoacid group significantly improves proton conductivities. At 60 °C, under 95% RH, the conductivity of the SPEEK/TpPa−SO₃H-20 composite membrane was 443.6 mS·cm⁻¹, which was 3.3 times that of the pristine SPEEK membrane. The pyridine group reduced the swelling ratio at 50 °C from 220.7% to 2.4%, indicating an enhancement in dimensional stability. Combining the benefits of sulfoacid and pyridine groups, SPEEK/TpPa−(SO₃H-Py) composite membrane has a conductivity of 360.3 mS·cm⁻¹ at 60 °C and 95% RH, which is 1.86 times that of SPEEK, and its swelling ratio is 11.8%, about 1/20 of that of SPEEK membrane. The method of in situ combination and regulation of groups open up a way for the development of SPEEK/COFs composite PEMs. Full article

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17 pages, 4729 KiB

Open AccessEditor’s ChoiceArticle

One-Pot Synthesis of MnO_x-SiO₂ Porous Composites as Nanozymes with ROS-Scavenging Properties

by M. Dolores Garrido, Jamal El Haskouri, María D. Marcos, Francisco Pérez-Pla, José Vicente Ros-Lis and Pedro Amorós

Nanomaterials 2022, 12(19), 3503; https://doi.org/10.3390/nano12193503 - 7 Oct 2022

Cited by 5 | Viewed by 2280

Abstract

The development of nanomaterials that mimic the activity of enzymes is a topic of interest, for the decomposition of reactive oxygen species (ROS). We report the preparation of a novel nanocomposite of MnO_x needles covered with SiO₂ porous material. The material [...] Read more.

The development of nanomaterials that mimic the activity of enzymes is a topic of interest, for the decomposition of reactive oxygen species (ROS). We report the preparation of a novel nanocomposite of MnO_x needles covered with SiO₂ porous material. The material was prepared in one pot with a two-step procedure. The material was characterized by EDX, SEM, TEM, XRD, nitrogen adsorption–desorption isotherms, and XPS. The synthesis protocol took advantage of the atrane method, favoring the nucleation and initial growth of manganese oxide needles that remained embedded and homogeneously dispersed in a mesoporous silica matrix. The final composite had a high concentration of Mn (Si/Mn molar ratio of ca. 1). The nanozyme presented bimodal porosity: intraparticle and interparticle association with the surfactant micelles and the gaps between silica particles and MnO_x needles, respectively. The porosity favored the migration of the reagent to the surface of the catalytic MnO_x. The nanozyme showed very efficient SOD and catalase activities, thus improving other materials previously described. The kinetics were studied in detail, and the reaction mechanisms were proposed. It was shown that silica does not play an innocent role in the case of catalase activity, increasing the reaction rate. Full article

(This article belongs to the Special Issue Recent Advances in the Construction and Applications of Nanozymes)

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10 pages, 826 KiB

Open AccessEditor’s ChoiceArticle

Ordered Bose Glass of Vortices in Superconducting YBa₂Cu₃O_7−δ Thin Films with a Periodic Pin Lattice Created by Focused Helium Ion Irradiation

by Lucas Backmeister, Bernd Aichner, Max Karrer, Katja Wurster, Reinhold Kleiner, Edward Goldobin, Dieter Koelle and Wolfgang Lang

Nanomaterials 2022, 12(19), 3491; https://doi.org/10.3390/nano12193491 - 6 Oct 2022

Cited by 8 | Viewed by 2283

Abstract

The defect-rich morphology of YBa₂Cu₃O_7−δ (YBCO) thin films leads to a glass-like arrangement of Abrikosov vortices which causes the resistance to disappear in vanishing current densities. This vortex glass consists of entangled vortex lines and is identified [...] Read more.

The defect-rich morphology of YBa₂Cu₃O_7−δ (YBCO) thin films leads to a glass-like arrangement of Abrikosov vortices which causes the resistance to disappear in vanishing current densities. This vortex glass consists of entangled vortex lines and is identified by a characteristic scaling of the voltage–current isotherms. Randomly distributed columnar defects stratify the vortex lines and lead to a Bose glass. Here, we report on the observation of an ordered Bose glass in a YBCO thin film with a hexagonal array of columnar defects with 30 nm spacings. The periodic pinning landscape was engineered by a focused beam of 30 keV He⁺ ions in a helium-ion microscope. Full article

(This article belongs to the Special Issue Superconductivity in Nanosystems)

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9 pages, 2701 KiB

Open AccessEditor’s ChoiceArticle

Double Fano Resonance and Independent Regulation Characteristics in a Rectangular-like Nanotetramer Metasurface Structure

by Zhidong Zhang, Qingchao Zhang, Bo Li, Junbin Zang, Xiyuan Cao, Xiaolong Zhao and Chenyang Xue

Nanomaterials 2022, 12(19), 3479; https://doi.org/10.3390/nano12193479 - 5 Oct 2022

Cited by 3 | Viewed by 1750

Abstract

Fano resonance, which is based on a plasmonic metasurface, has many potential applications in various fields, such as biochemical sensors, slow light effect, and integrated optical circuits. In this study, a rectangular-like nanotetramer metasurface structure composed of four round-head nanorods was designed. The [...] Read more.

Fano resonance, which is based on a plasmonic metasurface, has many potential applications in various fields, such as biochemical sensors, slow light effect, and integrated optical circuits. In this study, a rectangular-like nanotetramer metasurface structure composed of four round-head nanorods was designed. The transmission spectrum, surface charge, and electrical field distributions of the proposed structure were simulated using the finite element method. A double Fano resonance profile was observed in the transmission spectrum. One of the Fano resonances was caused by the symmetry breaking and plasmon hybridization between the horizontal double rods, whereas the other resonance was due to the plasmonic modes’ hybridization among four nanorods. These resonances could be independently tuned because of different formation mechanisms. The number of Fano resonances could be adjusted by changing the coupling distance between the horizontal and vertical rods. The results contributed to designing the highly sensitive sensors based on the plasmonic metasurface. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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15 pages, 1299 KiB

Open AccessEditor’s ChoiceReview

Upconversion Nanomaterials in Bioimaging and Biosensor Applications and Their Biological Response

by Zayakhuu Gerelkhuu, Yong-Ill Lee and Tae Hyun Yoon

Nanomaterials 2022, 12(19), 3470; https://doi.org/10.3390/nano12193470 - 4 Oct 2022

Cited by 10 | Viewed by 3282

Abstract

In recent decades, upconversion nanomaterials (UCNMs) have attracted considerable research interest because of their unique optical properties, such as large anti-Stokes shifts, sharp emissions, non-photobleaching, and long lifetime. These unique properties make them ideal candidates for unified applications in biomedical fields, including drug [...] Read more.

In recent decades, upconversion nanomaterials (UCNMs) have attracted considerable research interest because of their unique optical properties, such as large anti-Stokes shifts, sharp emissions, non-photobleaching, and long lifetime. These unique properties make them ideal candidates for unified applications in biomedical fields, including drug delivery, bioimaging, biosensing, and photodynamic therapy for specific cancers. This review describes the general mechanisms of upconversion, synthesis methods, and potential applications in biology and their biological responses. Additionally, the biological toxicity of UCNMs is explained and summarized with the associated intracellular association mechanisms. Finally, the prospects and future challenges of UCNMs at the clinical level in biological applications are described, along with a summary of opportunity for biological as well as clinical applications of UCNMs. Full article

(This article belongs to the Special Issue From Measurements to Predictive Models: Recent Advancements in Nanosafety Research)

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10 pages, 2543 KiB

Open AccessEditor’s ChoiceArticle

Single-Step Fabrication of Au-Fe-BaTiO₃ Nanocomposite Thin Films Embedded with Non-Equilibrium Au-Fe Alloyed Nanostructures

by Bethany X. Rutherford, Hongyi Dou, Bruce Zhang, Zihao He, James P. Barnard, Robynne L. Paldi and Haiyan Wang

Nanomaterials 2022, 12(19), 3460; https://doi.org/10.3390/nano12193460 - 3 Oct 2022

Cited by 5 | Viewed by 2014

Abstract

Nanocomposite thin film materials present great opportunities in coupling materials and functionalities in unique nanostructures including nanoparticles-in-matrix, vertically aligned nanocomposites (VANs), and nanolayers. Interestingly the nanocomposites processed through a non-equilibrium processing method, e.g., pulsed laser deposition (PLD), often possess unique metastable phases and [...] Read more.

Nanocomposite thin film materials present great opportunities in coupling materials and functionalities in unique nanostructures including nanoparticles-in-matrix, vertically aligned nanocomposites (VANs), and nanolayers. Interestingly the nanocomposites processed through a non-equilibrium processing method, e.g., pulsed laser deposition (PLD), often possess unique metastable phases and microstructures that could not achieve using equilibrium techniques, and thus lead to novel physical properties. In this work, a unique three-phase system composed of BaTiO₃ (BTO), with two immiscible metals, Au and Fe, is demonstrated. By adjusting the deposition laser frequency from 2 Hz to 10 Hz, the phase and morphology of Au and Fe nanoparticles in BTO matrix vary from separated Au and Fe nanoparticles to well-mixed Au-Fe alloy pillars. This is attributed to the non-equilibrium process of PLD and the limited diffusion under high laser frequency (e.g., 10 Hz). The magnetic and optical properties are effectively tuned based on the morphology variation. This work demonstrates the stabilization of non-equilibrium alloy structures in the VAN form and allows for the exploration of new non-equilibrium materials systems and their properties that could not be easily achieved through traditional equilibrium methods. Full article

(This article belongs to the Section Inorganic Materials and Metal-Organic Frameworks)

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11 pages, 1348 KiB

Open AccessEditor’s ChoiceArticle

Characteristics of Cellulose Nanofibrils from Transgenic Trees with Reduced Expression of Cellulose Synthase Interacting 1

by Simon Jonasson, Anne Bünder, Linn Berglund, Totte Niittylä and Kristiina Oksman

Nanomaterials 2022, 12(19), 3448; https://doi.org/10.3390/nano12193448 - 2 Oct 2022

Cited by 3 | Viewed by 2089

Abstract

Cellulose nanofibrils can be derived from the native load-bearing cellulose microfibrils in wood. These microfibrils are synthesized by a cellulose synthase enzyme complex that resides in the plasma membrane of developing wood cells. It was previously shown that transgenic hybrid aspen trees with [...] Read more.

Cellulose nanofibrils can be derived from the native load-bearing cellulose microfibrils in wood. These microfibrils are synthesized by a cellulose synthase enzyme complex that resides in the plasma membrane of developing wood cells. It was previously shown that transgenic hybrid aspen trees with reduced expression of CSI1 have different wood mechanics and cellulose microfibril properties. We hypothesized that these changes in the native cellulose may affect the quality of the corresponding nanofibrils. To test this hypothesis, wood from wild-type and transgenic trees with reduced expression of CSI1 was subjected to oxidative nanofibril isolation. The transgenic wood-extracted nanofibrils exhibited a significantly lower suspension viscosity and estimated surface area than the wild-type nanofibrils. Furthermore, the nanofibril networks manufactured from the transgenics exhibited high stiffness, as well as reduced water uptake, tensile strength, strain-to-break, and degree of polymerization. Presumably, the difference in wood properties caused by the decreased expression of CSI1 resulted in nanofibrils with distinctive qualities. The observed changes in the physicochemical properties suggest that the differences were caused by changes in the apparent nanofibril aspect ratio and surface accessibility. This study demonstrates the possibility of influencing wood-derived nanofibril quality through the genetic engineering of trees. Full article

(This article belongs to the Section Environmental Nanoscience and Nanotechnology)

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18 pages, 6322 KiB

Open AccessEditor’s ChoiceArticle

Graphene-Based Composites with Silver Nanowires for Electronic Applications

by Dimitra Giasafaki, Christina Mitzithra, Vassiliki Belessi, Theodora Filippakopoulou, Apostolos Koutsioukis, Vasilios Georgakilas, Georgia Charalambopoulou and Theodore Steriotis

Nanomaterials 2022, 12(19), 3443; https://doi.org/10.3390/nano12193443 - 1 Oct 2022

Cited by 17 | Viewed by 3428

Abstract

Graphene/metal nanocomposites have shown a strong potential for use in electronic applications. In particular, the combination of silver nanowires (AgNWs) with graphene derivatives leads to the formation of an efficient conductive network, thus improving the electrical properties of a composite. This work focused [...] Read more.

Graphene/metal nanocomposites have shown a strong potential for use in electronic applications. In particular, the combination of silver nanowires (AgNWs) with graphene derivatives leads to the formation of an efficient conductive network, thus improving the electrical properties of a composite. This work focused on developing highly conductive hydrophilic hybrids of simultaneously functionalized and reduced graphene oxide (f-rGO) and AgNWs in different weight ratios by following two different synthetic routes: (a) the physical mixture of f-rGO and AgNWs, and (b) the in situ reduction of GO in the presence of AgNWs. In addition, the role of AgNWs in improving the electrical properties of graphene derivatives was further examined by mixing AgNWs with a hybrid of few-layered graphene with functionalized multiwalled carbon nanotubes (FLG/MWNT-f-OH). The studied materials showed a remarkable improvement in the overall electrical conductivity due to the synergistic effect of their components, which was proportional to the percentage of Ag and dependent on the procedure of the hybrid formation. One of the f-rGO/AgNWs composites was also selected for the preparation of gravure printing inks that were tested to determine their rheological and printing properties. All of the f-rGO/AgNWs composites were shown to be very promising materials for use as conductive inks for flexible electronics. Full article

(This article belongs to the Special Issue Conductive Ink Based Nanocomposites for Advanced Printing Applications)

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14 pages, 1695 KiB

Open AccessEditor’s ChoiceArticle

Dynamic Fluid Flow Exacerbates the (Pro-)Inflammatory Effects of Aerosolised Engineered Nanomaterials In Vitro

by Kirsty Meldrum, Joana A. Moura, Shareen H. Doak and Martin J. D. Clift

Nanomaterials 2022, 12(19), 3431; https://doi.org/10.3390/nano12193431 - 30 Sep 2022

Cited by 6 | Viewed by 2677

Abstract

The majority of in vitro studies focusing upon particle–lung cell interactions use static models at an air–liquid interface (ALI). Advancing the physiological characteristics of such systems allows for closer resemblance of the human lung, in turn promoting 3R strategies. PATROLS (EU Horizon 2020 [...] Read more.

The majority of in vitro studies focusing upon particle–lung cell interactions use static models at an air–liquid interface (ALI). Advancing the physiological characteristics of such systems allows for closer resemblance of the human lung, in turn promoting 3R strategies. PATROLS (EU Horizon 2020 No. 760813) aimed to use a well-characterised in vitro model of the human alveolar epithelial barrier to determine how fluid-flow dynamics would impact the outputs of the model following particle exposure. Using the QuasiVivo^TM (Kirkstall Ltd., York, UK) system, fluid-flow conditions were applied to an A549 + dTHP-1 cell co-culture model cultured at the ALI. DQ₁₂ and TiO₂ (JRCNM01005a) were used as model particles to assess the in vitro systems’ sensitivity. Using a quasi- and aerosol (VitroCell Cloud12, VitroCell Systems, Waldkirch, Germany) exposure approach, cell cultures were exposed over 24 h at IVIVE concentrations of 1 and 10 (DQ₁₂) and 1.4 and 10.4 (TiO₂) µg/cm², respectively. We compared static and fluid flow conditions after both these exposure methods. The co-culture was subsequently assessed for its viability, membrane integrity and (pro-)inflammatory response (IL-8 and IL-6 production). The results suggested that the addition of fluid flow to this alveolar co-culture model can influence the viability, membrane integrity and inflammatory responses dependent on the particle type and exposure. Full article

(This article belongs to the Section Biology and Medicines)

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16 pages, 2697 KiB

Open AccessEditor’s ChoiceArticle

Gelatin Nanoparticles for Complexation and Enhanced Cellular Delivery of mRNA

by Lea Andrée, Rik Oude Egberink, Josephine Dodemont, Negar Hassani Besheli, Fang Yang, Roland Brock and Sander C. G. Leeuwenburgh

Nanomaterials 2022, 12(19), 3423; https://doi.org/10.3390/nano12193423 - 29 Sep 2022

Cited by 15 | Viewed by 3399

Abstract

Messenger RNA (mRNA) is increasingly gaining interest as a modality in vaccination and protein replacement therapy. In regenerative medicine, the mRNA-mediated expression of growth factors has shown promising results. In contrast to protein delivery, successful mRNA delivery requires a vector to induce cellular [...] Read more.

Messenger RNA (mRNA) is increasingly gaining interest as a modality in vaccination and protein replacement therapy. In regenerative medicine, the mRNA-mediated expression of growth factors has shown promising results. In contrast to protein delivery, successful mRNA delivery requires a vector to induce cellular uptake and subsequent endosomal escape to reach its end destination, the ribosome. Current non-viral vectors such as lipid- or polymer-based nanoparticles have been successfully used to express mRNA-encoded proteins. However, to advance the use of mRNA in regenerative medicine, it is required to assess the compatibility of mRNA with biomaterials that are typically applied in this field. Herein, we investigated the complexation, cellular uptake and maintenance of the integrity of mRNA complexed with gelatin nanoparticles (GNPs). To this end, GNPs with positive, neutral or negative surface charge were synthesized to assess their ability to bind and transport mRNA into cells. Positively charged GNPs exhibited the highest binding affinity and transported substantial amounts of mRNA into pre-osteoblastic cells, as assessed by confocal microscopy using fluorescently labeled mRNA. Furthermore, the GNP-bound mRNA remained stable. However, no expression of mRNA-encoded protein was detected, which is likely related to insufficient endosomal escape and/or mRNA release from the GNPs. Our results indicate that gelatin-based nanomaterials interact with mRNA in a charge-dependent manner and also mediate cellular uptake. These results create the basis for the incorporation of further functionality to yield endosomal release. Full article

(This article belongs to the Special Issue Nanoparticles in Regenerative Medicine)

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22 pages, 7005 KiB

Open AccessEditor’s ChoiceArticle

Functional Silane-Based Nanohybrid Materials for the Development of Hydrophobic and Water-Based Stain Resistant Cotton Fabrics Coatings

by Silvia Sfameni, Tim Lawnick, Giulia Rando, Annamaria Visco, Torsten Textor and Maria Rosaria Plutino

Nanomaterials 2022, 12(19), 3404; https://doi.org/10.3390/nano12193404 - 28 Sep 2022

Cited by 23 | Viewed by 4760

Abstract

The textile-finishing industry, is one of the main sources of persistent organic pollutants in water; in this regard, it is necessary to develop and employ new sustainable approaches for fabric finishing and treatment. This research study shows the development of an efficient and [...] Read more.

The textile-finishing industry, is one of the main sources of persistent organic pollutants in water; in this regard, it is necessary to develop and employ new sustainable approaches for fabric finishing and treatment. This research study shows the development of an efficient and eco-friendly procedure to form highly hydrophobic surfaces on cotton fabrics using different modified silica sols. In particular, the formation of highly hydrophobic surfaces on cotton fabrics was studied by using a two-step treatment procedure, i.e., first applying a hybrid silica sol obtained by hydrolysis and subsequent condensation of (3-Glycidyloxypropyl)trimethoxy silane with different alkyl(trialkoxy)silane under acid conditions, and then applying hydrolyzed hexadecyltrimethoxysilane on the treated fabrics to further improve the fabrics’ hydrophobicity. The treated cotton fabrics showed excellent water repellency with a water contact angle above 150° under optimum treatment conditions. The cooperative action of rough surface structure due to the silica sol nanoparticles and the low surface energy caused by long-chain alkyl(trialkoxy)silane in the nanocomposite coating, combined with the expected roughness on microscale due to the fabrics and fiber structure, provided the treated cotton fabrics with excellent, almost super, hydrophobicity and water-based stain resistance in an eco-sustainable way. Full article

(This article belongs to the Special Issue Nanomaterials for Chemical Engineering)

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10 pages, 2881 KiB

Open AccessEditor’s ChoiceArticle

Smart Modulators Based on Electric Field-Triggering of Surface Plasmon–Polariton for Active Plasmonics

by Jan Švanda, Yevgeniya Kalachyova, David Mareš, Jakub Siegel, Petr Slepička, Zdeňka Kolská, Petr Macháč, Štefan Michna, Václav Švorčík and Oleksiy Lyutakov

Nanomaterials 2022, 12(19), 3366; https://doi.org/10.3390/nano12193366 - 27 Sep 2022

Cited by 1 | Viewed by 1646

Abstract

Design and properties of a plasmonic modulator in situ tunable by electric field are presented. Our design comprises the creation of periodic surface pattern on the surface of an elastic polymer supported by a piezo–substrate by excimer laser irradiation and subsequent selective coverage [...] Read more.

Design and properties of a plasmonic modulator in situ tunable by electric field are presented. Our design comprises the creation of periodic surface pattern on the surface of an elastic polymer supported by a piezo–substrate by excimer laser irradiation and subsequent selective coverage by silver by tilted angle vacuum evaporation. The structure creation was confirmed by AFM and FIB-SEM techniques. An external electric field is used for fine control of the polymer pattern amplitude, which tends to decrease with increasing voltage. As a result, surface plasmon–polariton excitation is quenched, leading to the less pronounced structure of plasmon response. This quenching was checked using UV–Vis spectroscopy and SERS measurements, and confirmed by numerical simulation. All methods prove the proposed functionality of the structures enabling the creation smart plasmonic materials for a very broad range of advanced optical applications. Full article

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14 pages, 11215 KiB

Open AccessEditor’s ChoiceArticle

Synthesis, Characterization, and Electrochemical Properties of La-Doped α-Fe₂O₃ Nanoparticles

by Hewei Wang, Peiyang Shi and Junxiang Ning

Nanomaterials 2022, 12(19), 3346; https://doi.org/10.3390/nano12193346 - 26 Sep 2022

Cited by 4 | Viewed by 1898

Abstract

La-doped α-Fe₂O₃ nanoparticles were synthesized by a hydrothermal method. The effects of pH value on the morphology, structure, and electrochemical stability of the La-doped α-Fe₂O₃ nanoparticles were investigated by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectrum, [...] Read more.

La-doped α-Fe₂O₃ nanoparticles were synthesized by a hydrothermal method. The effects of pH value on the morphology, structure, and electrochemical stability of the La-doped α-Fe₂O₃ nanoparticles were investigated by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectrum, and electrochemical methods. The results show that the La-doped α-Fe₂O₃ nanoparticles exhibit a uniform spherical morphology at pH = 6, and are agglomerated with a poor dispersion at pH = 4 and 8. The iron oxide lattice is distorted by the La-doping, which increases the Fe–O bond strength. The decreased Fe–O bond length and the increased Fe–O bond energy at pH = 6 improve the electrochemical stability of α-Fe₂O₃. The waterborne coating modified with La-doped α-Fe₂O₃ nanoparticles exhibits a steady corrosion resistance. Full article

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18 pages, 2353 KiB

Open AccessEditor’s ChoiceArticle

Interactions between ZnO Nanoparticles and Polyphenols Affect Biological Responses

by Su-Bin Kim, Na-Kyung Yoo and Soo-Jin Choi

Nanomaterials 2022, 12(19), 3337; https://doi.org/10.3390/nano12193337 - 25 Sep 2022

Cited by 8 | Viewed by 2738

Abstract

Zinc oxide (ZnO) nanoparticles (NPs) are used as a food additive Zn supplement due to the role of Zn in biological functions. They are directly added to complex processed foods or Zn-fortified functional foods. Hence, the interactions between ZnO NPs and nutritional or [...] Read more.

Zinc oxide (ZnO) nanoparticles (NPs) are used as a food additive Zn supplement due to the role of Zn in biological functions. They are directly added to complex processed foods or Zn-fortified functional foods. Hence, the interactions between ZnO NPs and nutritional or functional components can occur. In this study, the effects of ZnO NP interactions with two polyphenols (quercetin and rutin) on cytotoxicity, antioxidant activity, ex vivo intestinal absorption, and solubility were evaluated. Moreover, the characterization on the interactions was carried out by analyzing crystallinity, surface chemical bonding, chemical composition, and surface chemistry. The results demonstrate that the interactions caused higher cytotoxicity, ex vivo intestinal transport, and solubility of ZnO NPs than pristine ZnO NPs but did not affect antioxidant activity nor intestinal absorption of the polyphenols. The interaction effects were more evident by ZnO NPs interacted with quercetin than with rutin. The crystallinity of ZnO NPs was not influenced, but the degree of exposure of the chemical bondings, elemental compositions, and chemical group intensities on the surface of ZnO NPs, quercetin, or rutin were quenched or decreased to some extent by the interactions, especially by ZnO NPs interacted with quercetin. It is, therefore, concluded that the interactions affect chemical characteristics and surface chemical sates of ZnO NPs, quercetin, or rutin, which can cause high cytotoxicity, intestinal absorption, and solubility of ZnO NPs. Further study is required to elucidate the mechanism of action of the interactions. Full article

(This article belongs to the Special Issue Nanomaterials in Foods: Food Additives, Delivery Systems, Detection, and Safety)

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13 pages, 2955 KiB

Open AccessEditor’s ChoiceArticle

Stainless Steel-Supported Amorphous Nickel Phosphide/Nickel as an Electrocatalyst for Hydrogen Evolution Reaction

by Gaoyang Liu, Faguo Hou, Xindong Wang and Baizeng Fang

Nanomaterials 2022, 12(19), 3328; https://doi.org/10.3390/nano12193328 - 24 Sep 2022

Cited by 8 | Viewed by 2459

Abstract

Recently, nickel phosphides (Ni-P) in an amorphous state have emerged as potential catalysts with high intrinsic activity and excellent electrochemical stability for hydrogen evolution reactions (HER). However, it still lacks a good strategy to prepare amorphous Ni-P with rich surface defects or structural [...] Read more.

Recently, nickel phosphides (Ni-P) in an amorphous state have emerged as potential catalysts with high intrinsic activity and excellent electrochemical stability for hydrogen evolution reactions (HER). However, it still lacks a good strategy to prepare amorphous Ni-P with rich surface defects or structural boundaries, and it is also hard to construct a porous Ni-P layer with favorable electron transport and gas–liquid transport. Herein, an integrated porous electrode consisting of amorphous Ni-P and a Ni interlayer was successfully constructed on a 316L stainless steel felt (denoted as Ni-P/Ni-316L). The results demonstrated that the pH of the plating solution significantly affected the grain size, pore size and distribution, and roughness of the cell-like particle surface of the amorphous Ni-P layer. The Ni-P/Ni-316L prepared at pH = 3 presented the richest surface defects or structural boundaries as well as porous structure. As expected, the as-developed Ni-P/Ni-316L demonstrated the best kinetics, with

η_{10}

of 73 mV and a Tafel slope of ca. 52 mV dec-1 for the HER among all the electrocatalysts prepared at various pH values. Furthermore, the Ni-P/Ni-316L exhibited comparable electrocatalytic HER performance and better durability than the commercial Pt (20 wt%)/C in a real water electrolysis cell, indicating that the non-precious metal-based Ni-P/Ni-316L is promising for large-scale processing and practical use. Full article

(This article belongs to the Special Issue Advances in Novel Nanostructured Materials for Electrocatalysis–Trends and Future)

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27 pages, 24240 KiB

Open AccessEditor’s ChoiceArticle

Development of a TiO₂/Sepiolite Photocatalyst for the Degradation of a Persistent Organic Pollutant in Aqueous Solution

by Amina Bakhtiar, Zohra Bouberka, Pascal Roussel, Christophe Volkringer, Ahmed Addad, Baghdad Ouddane, Christel Pierlot and Ulrich Maschke

Nanomaterials 2022, 12(19), 3313; https://doi.org/10.3390/nano12193313 - 23 Sep 2022

Cited by 10 | Viewed by 2679

Abstract

A clay-based TiO₂ nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO₂ nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in [...] Read more.

A clay-based TiO₂ nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO₂ nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO₂ particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO₂ particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO₂ beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO₂ nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO₂ materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency. Full article

(This article belongs to the Special Issue Nanomaterials in Catalysis for Environmental and Energy Applications)

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16 pages, 5601 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Advances of Transition Metal Chalcogenides as Cathode Materials for Aqueous Zinc-Ion Batteries

by Ying Liu and Xiang Wu

Nanomaterials 2022, 12(19), 3298; https://doi.org/10.3390/nano12193298 - 22 Sep 2022

Cited by 9 | Viewed by 3957

Abstract

In recent years, advances in lithium-ion batteries (LIBs) have pushed the research of other metal-ion batteries to the forefront. Aqueous zinc ion batteries (AZIBs) have attracted much attention owing to their low cost, high capacity and non-toxic characteristics. Among various cathodes, transition metal [...] Read more.

In recent years, advances in lithium-ion batteries (LIBs) have pushed the research of other metal-ion batteries to the forefront. Aqueous zinc ion batteries (AZIBs) have attracted much attention owing to their low cost, high capacity and non-toxic characteristics. Among various cathodes, transition metal chalcogenides (TMCs) with a layered structure are considered as suitable electrode materials. The large layer spacing facilitates the intercalation/de-intercalation of Zn²⁺ between the layers. In this mini-review, we summarize a variety of design strategies for the modification of TMCs. Then, we specifically emphasize the zinc storage capacity of the optimized electrodes. Finally, we propose the challenges and future prospects of cathode materials for high-energy AZIBs. Full article

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

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32 pages, 3047 KiB

Open AccessEditor’s ChoiceReview

Adverse Outcome Pathways Associated with the Ingestion of Titanium Dioxide Nanoparticles—A Systematic Review

by Dora Rolo, Ricardo Assunção, Célia Ventura, Paula Alvito, Lídia Gonçalves, Carla Martins, Ana Bettencourt, Peter Jordan, Nádia Vital, Joana Pereira, Fátima Pinto, Paulo Matos, Maria João Silva and Henriqueta Louro

Nanomaterials 2022, 12(19), 3275; https://doi.org/10.3390/nano12193275 - 21 Sep 2022

Cited by 25 | Viewed by 4937

Abstract

Titanium dioxide nanoparticles (TiO₂-NPs) are widely used, and humans are exposed through food (E171), cosmetics (e.g., toothpaste), and pharmaceuticals. The oral and gastrointestinal (GIT) tract are the first contact sites, but it may be systemically distributed. However, a robust adverse outcome [...] Read more.

Titanium dioxide nanoparticles (TiO₂-NPs) are widely used, and humans are exposed through food (E171), cosmetics (e.g., toothpaste), and pharmaceuticals. The oral and gastrointestinal (GIT) tract are the first contact sites, but it may be systemically distributed. However, a robust adverse outcome pathway (AOP) has not been developed upon GIT exposure to TiO₂-NPs. The aim of this review was to provide an integrative analysis of the published data on cellular and molecular mechanisms triggered after the ingestion of TiO₂-NPs, proposing plausible AOPs that may drive policy decisions. A systematic review according to Prisma Methodology was performed in three databases of peer-reviewed literature: Pubmed, Scopus, and Web of Science. A total of 787 records were identified, screened in title/abstract, being 185 used for data extraction. The main endpoints identified were oxidative stress, cytotoxicity/apoptosis/cell death, inflammation, cellular and systemic uptake, genotoxicity, and carcinogenicity. From the results, AOPs were proposed where colorectal cancer, liver injury, reproductive toxicity, cardiac and kidney damage, as well as hematological effects stand out as possible adverse outcomes. The recent transgenerational studies also point to concerns with regard to population effects. Overall, the findings further support a limitation of the use of TiO₂-NPs in food, announced by the European Food Safety Authority (EFSA). Full article

(This article belongs to the Special Issue New Insights in Toxicity and Cytotoxicity of Nanomaterials)

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25 pages, 6929 KiB

Open AccessEditor’s ChoiceArticle

Nanocomposites of Titanium Dioxide and Peripherally Substituted Phthalocyanines for the Photocatalytic Degradation of Sulfamethoxazole

by Joanna Musial, Artium Belet, Dariusz T. Mlynarczyk, Michal Kryjewski, Tomasz Goslinski, Stéphanie D. Lambert, Dirk Poelman and Beata J. Stanisz

Nanomaterials 2022, 12(19), 3279; https://doi.org/10.3390/nano12193279 - 21 Sep 2022

Cited by 10 | Viewed by 3036

Abstract

Phthalocyanines (Pcs) are often used in photosensitization of titanium(IV) oxide, a commonly employed photocatalyst, as such an approach holds the promise of obtaining highly stable and efficient visible light-harvesting materials. Herein, we report on the preparation, characterization and photoactivity of a series of [...] Read more.

Phthalocyanines (Pcs) are often used in photosensitization of titanium(IV) oxide, a commonly employed photocatalyst, as such an approach holds the promise of obtaining highly stable and efficient visible light-harvesting materials. Herein, we report on the preparation, characterization and photoactivity of a series of composites based on TiO₂ and peripherally modified metallophthalocyanines: either tetrasulfonated or 4,4′,4′′,4′′′-tetraazaphthalocyanines, with either copper(II), nickel(II) or zinc(II) as the central metal ion. Physicochemical characterization was performed using UV-Vis diffuse reflectance spectroscopy, hydrodynamic particle-size analysis, surface-area analysis using N₂ adsorption-desorption measurements and thermogravimetry combined with differential scanning calorimetry. The band-gap energy values were lower for the composites with peripherally modified phthalocyanines than for the commercial TiO₂ P25 or the unsubstituted zinc(II) phthalocyanine-grafted TiO₂. TG–DSC results confirmed that the chemical deposition, used for the preparation of Pc/TiO₂ composites, is a simple and efficient method for TiO₂ surface modification, as all the Pc load was successfully grafted on TiO₂. The photocatalytic potential of the Pc/TiO₂ materials was assessed in the photocatalytic removal of sulfamethoxazole—a commonly used antibacterial drug of emerging ecological concern. To compare the activity of the materials in different conditions, photodegradation tests were conducted both in water and in an organic medium. Full article

(This article belongs to the Special Issue Engineering Nanoparticles for Photocatalytic Applications)

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15 pages, 4627 KiB

Open AccessEditor’s ChoiceArticle

Comparative Analysis of LiMPO₄ (M = Fe, Co, Cr, Mn, V) as Cathode Materials for Lithium-Ion Battery Applications—A First-Principle-Based Theoretical Approach

by Sayan Kanungo, Ankur Bhattacharjee, Naresh Bahadursha and Aritra Ghosh

Nanomaterials 2022, 12(19), 3266; https://doi.org/10.3390/nano12193266 - 20 Sep 2022

Cited by 22 | Viewed by 4016

Abstract

The rapidly increasing demand for energy storage has been consistently driving the exploration of different materials for Li-ion batteries, where the olivine lithium-metal phosphates (LiMPO₄) are considered one of the most potential candidates for cathode-electrode design. In this context, the work [...] Read more.

The rapidly increasing demand for energy storage has been consistently driving the exploration of different materials for Li-ion batteries, where the olivine lithium-metal phosphates (LiMPO₄) are considered one of the most potential candidates for cathode-electrode design. In this context, the work presents an extensive comparative theoretical study of the electrochemical and electrical properties of iron (Fe)-, cobalt (Co)-, manganese (Mn)-, chromium (Cr)-, and vanadium (V)-based LiMPO₄ materials for cathode design in lithium (Li)-ion battery applications, using the density-functional-theory (DFT)-based first-principle-calculation approach. The work emphasized different material and performance aspects of the cathode design, including the cohesive energy of the material, Li-intercalation energy in olivine structure, and intrinsic diffusion coefficient across the Li channel, as well as equilibrium potential and open-circuit potential at different charge-states of Li-ion batteries. The results indicate the specification of the metal atom significantly influences the Li diffusion across the olivine structure and the overall energetics of different LiMPO₄. In this context, a clear correlation between the structural and electrochemical properties has been demonstrated in different LiMPO₄. The key findings offer significant theoretical and design-level insight for estimating the performance of studied LiMPO₄-based Li-ion batteries while interfacing with different application areas. Full article

(This article belongs to the Special Issue The Role of Nanofluids in Renewable Energy Engineering)

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12 pages, 3801 KiB

Open AccessEditor’s ChoiceArticle

Highly Luminescent and Photostable Core/Shell/Shell ZnSeS/Cu:ZnS/ZnS Quantum Dots Prepared via a Mild Aqueous Route

by Salima Mabrouk, Hervé Rinnert, Lavinia Balan, Jordane Jasniewski, Sébastien Blanchard, Ghouti Medjahdi, Rafik Ben Chaabane and Raphaël Schneider

Nanomaterials 2022, 12(18), 3254; https://doi.org/10.3390/nano12183254 - 19 Sep 2022

Cited by 2 | Viewed by 2449

Abstract

An aqueous-phase synthesis of 3-mercaptopropionic acid (3-MPA)-capped core/shell/shell ZnSeS/Cu:ZnS/ZnS QDs was developed. The influence of the Cu-dopant location on the photoluminescence (PL) emission intensity was investigated, and the results show that the introduction of the Cu dopant in the first ZnS shell leads [...] Read more.

An aqueous-phase synthesis of 3-mercaptopropionic acid (3-MPA)-capped core/shell/shell ZnSeS/Cu:ZnS/ZnS QDs was developed. The influence of the Cu-dopant location on the photoluminescence (PL) emission intensity was investigated, and the results show that the introduction of the Cu dopant in the first ZnS shell leads to QDs exhibiting the highest PL quantum yield (25%). The influence of the Cu-loading in the dots on the PL emission was also studied, and a shift from blue–green to green was observed with the increase of the Cu doping from 1.25 to 7.5%. ZnSeS/Cu:ZnS/ZnS QDs exhibit an average diameter of 2.1 ± 0.3 nm and are stable for weeks in aqueous solution. Moreover, the dots were found to be photostable under the continuous illumination of an Hg–Xe lamp and in the presence of oxygen, indicating their high potential for applications such as sensing or bio-imaging. Full article

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15 pages, 5072 KiB

Open AccessEditor’s ChoiceArticle

Exciton Manifolds in Highly Ambipolar Doped WS₂

by David Otto Tiede, Nihit Saigal, Hossein Ostovar, Vera Döring, Hendrik Lambers and Ursula Wurstbauer

Nanomaterials 2022, 12(18), 3255; https://doi.org/10.3390/nano12183255 - 19 Sep 2022

Viewed by 2516

Abstract

The disentanglement of single and many particle properties in 2D semiconductors and their dependencies on high carrier concentration is challenging to experimentally study by pure optical means. We establish an electrolyte gated WS

_{2}

monolayer field-effect structure capable of shifting the Fermi level [...] Read more.

The disentanglement of single and many particle properties in 2D semiconductors and their dependencies on high carrier concentration is challenging to experimentally study by pure optical means. We establish an electrolyte gated WS

_{2}

monolayer field-effect structure capable of shifting the Fermi level from the valence into the conduction band that is suitable to optically trace exciton binding as well as the single-particle band gap energies in the weakly doped regime. Combined spectroscopic imaging ellipsometry and photoluminescence spectroscopies spanning large n- and p-type doping with charge carrier densities up to 10

^{14}

cm

^{- 2}

enable to study screening phenomena and doping dependent evolution of the rich exciton manifold whose origin is controversially discussed in literature. We show that the two most prominent emission bands in photoluminescence experiments are due to the recombination of spin-forbidden and momentum-forbidden charge neutral excitons activated by phonons. The observed interband transitions are redshifted and drastically weakened under electron or hole doping. This field-effect platform is not only suitable for studying exciton manifold but is also suitable for combined optical and transport measurements on degenerately doped atomically thin quantum materials at cryogenic temperatures. Full article

(This article belongs to the Special Issue Recent Advances in Optical Spectroscopy of Layered Materials)

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12 pages, 3454 KiB

Open AccessEditor’s ChoiceArticle

Synthesis of Mesoporous Silica Adsorbent Modified with Mercapto–Amine Groups for Selective Adsorption of Cu²⁺ Ion from Aqueous Solution

by Sagar M. Mane, Chaitany Jayprakash Raorane and Jae Cheol Shin

Nanomaterials 2022, 12(18), 3232; https://doi.org/10.3390/nano12183232 - 18 Sep 2022

Cited by 8 | Viewed by 2410

Abstract

In a sol–gel co-condensation, a mesoporous silica hybrid integrated with (3-mercaptopropyl)trimethoxysilane (TMPSH) was prepared and then reacted with allylamine via a post-surface functionalization approach. Approximately 15 mol% of TMSPSH was introduced into the mesoporous silica pore walls along with tetraethyl orthosilicate. The mercapto [...] Read more.

In a sol–gel co-condensation, a mesoporous silica hybrid integrated with (3-mercaptopropyl)trimethoxysilane (TMPSH) was prepared and then reacted with allylamine via a post-surface functionalization approach. Approximately 15 mol% of TMSPSH was introduced into the mesoporous silica pore walls along with tetraethyl orthosilicate. The mercapto ligands in the prepared mesoporous silica pore walls were then reacted with allylamine (AM) to form the mercapto–amine-modified mesoporous silica adsorbent (MSH@MA). The MSH@MA NPs demonstrate highly selective adsorption of copper (Cu²⁺) ions (~190 mg/g) with a fast equilibrium adsorption time (30 min). The prepared adsorbent shows at least a five times more efficient recyclable stability. The MSH@MA NPs adsorbent is useful for selective adsorption of Cu²⁺ ions. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Environmental Remediation)

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18 pages, 6452 KiB

Open AccessEditor’s ChoiceArticle

Simulation of the Nucleation and Crystal Growth Process in the Laser-Induced Deposition in Solution by a Lattice Boltzmann Method

by Yongsen He and Siyu Liu

Nanomaterials 2022, 12(18), 3213; https://doi.org/10.3390/nano12183213 - 16 Sep 2022

Cited by 3 | Viewed by 2393

Abstract

A Lattice Boltzmann model is proposed, combining the theories of nucleation and crystal growth for the study of the laser-induced deposition in solution (LIDS). The conjugate heat transfer and the natural convection of the liquid precursor were simulated with the evolving interface of [...] Read more.

A Lattice Boltzmann model is proposed, combining the theories of nucleation and crystal growth for the study of the laser-induced deposition in solution (LIDS). The conjugate heat transfer and the natural convection of the liquid precursor were simulated with the evolving interface of crystal growth. In turn, the morphology of the deposited materials was affected by multiple process parameters, including conditions of chemical precursor and the laser-induced heat and mass transfer. Simulation results indicated that the morphology of deposited materials was mostly affected by the initial concentration of the precursor solution. Specifically, the nonuniformity of thin films was caused by the convection induced by the pulsed-laser, and the surface roughness was due to the competition of local structures for the precursor supply. A relationship of process-condition-material was established, providing guidance of choosing various parameters in LIDS for a desirable morphology of deposited material, facilitating the capabilities of pulsed lasers in precise control in nanomanufacturing. Full article

(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience - II)

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16 pages, 6462 KiB

Open AccessEditor’s ChoiceArticle

Conservation of Archaeological Bones: Assessment of Innovative Phosphate Consolidants in Comparison with Paraloid B72

by Andrea Díaz-Cortés, Gabriela Graziani, Marco Boi, Lucia López-Polín and Enrico Sassoni

Nanomaterials 2022, 12(18), 3163; https://doi.org/10.3390/nano12183163 - 13 Sep 2022

Cited by 6 | Viewed by 2670

Abstract

Aqueous solutions of diammonium hydrogen phosphate (DAP) have been recently proposed for consolidation of archeological bones, as an alternative to traditional products. Here, we investigated several routes to improve the performance of the DAP-based treatment, namely increasing the DAP concentration, adding calcium ions [...] Read more.

Aqueous solutions of diammonium hydrogen phosphate (DAP) have been recently proposed for consolidation of archeological bones, as an alternative to traditional products. Here, we investigated several routes to improve the performance of the DAP-based treatment, namely increasing the DAP concentration, adding calcium ions and adding ethanol to the DAP solution. Archaeological bones dated to about 1–0.8 million years ago were used for the tests. After preliminary screening by FTIR microscopy and FEG-SEM among different formulations, confirming the formation of new hydroxyapatite phases, the most promising formulation was selected, namely a 3 M DAP solution. The strengthening ability of this formulation was systematically compared to that of the most widely used commercial consolidant, namely Paraloid B72. The performance of the two treatments was evaluated in terms of Knoop and Vickers microhardness, resistance to scratch and resistance to material loss by peeling off. The results of the study show that the DAP treatment was able to improve the bone surface properties and also the resistance to material loss by peeling off, which is more dependent on in-depth consolidation. Paraloid B72 led to the formation of a layer of acrylic resin on the bone surface, which influenced the mechanical tests. Nonetheless, Paraloid B72 was able to penetrate in depth and substantially decrease the material loss by peeling off, even more effectively than DAP. The results of this study indicate that the potential of the DAP treatment for bone consolidation is confirmed. Full article

(This article belongs to the Special Issue Applications of Calcium Phosphates-Based Nanostructured Materials and Coatings)

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23 pages, 2534 KiB

Open AccessEditor’s ChoiceReview

Metal-Polymer Nanoconjugates Application in Cancer Imaging and Therapy

by André Q. Figueiredo, Carolina F. Rodrigues, Natanael Fernandes, Duarte de Melo-Diogo, Ilídio J. Correia and André F. Moreira

Nanomaterials 2022, 12(18), 3166; https://doi.org/10.3390/nano12183166 - 13 Sep 2022

Cited by 13 | Viewed by 3459

Abstract

Metallic-based nanoparticles present a unique set of physicochemical properties that support their application in different fields, such as electronics, medical diagnostics, and therapeutics. Particularly, in cancer therapy, the plasmonic resonance, magnetic behavior, X-ray attenuation, and radical oxygen species generation capacity displayed by metallic [...] Read more.

Metallic-based nanoparticles present a unique set of physicochemical properties that support their application in different fields, such as electronics, medical diagnostics, and therapeutics. Particularly, in cancer therapy, the plasmonic resonance, magnetic behavior, X-ray attenuation, and radical oxygen species generation capacity displayed by metallic nanoparticles make them highly promising theragnostic solutions. Nevertheless, metallic-based nanoparticles are often associated with some toxicological issues, lack of colloidal stability, and establishment of off-target interactions. Therefore, researchers have been exploiting the combination of metallic nanoparticles with other materials, inorganic (e.g., silica) and/or organic (e.g., polymers). In terms of biological performance, metal-polymer conjugation can be advantageous for improving biocompatibility, colloidal stability, and tumor specificity. In this review, the application of metallic-polymer nanoconjugates/nanohybrids as a multifunctional all-in-one solution for cancer therapy will be summarized, focusing on the physicochemical properties that make metallic nanomaterials capable of acting as imaging and/or therapeutic agents. Then, an overview of the main advantages of metal-polymer conjugation as well as the most common structural arrangements will be provided. Moreover, the application of metallic-polymer nanoconjugates/nanohybrids made of gold, iron, copper, and other metals in cancer therapy will be discussed, in addition to an outlook of the current solution in clinical trials. Full article

(This article belongs to the Special Issue Applications of Nanomaterials in Biomedical Imaging and Cancer Therapy II)

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19 pages, 2705 KiB

Open AccessEditor’s ChoiceArticle

Antibiotic-Loaded Hyperbranched Polyester Embedded into Peptide-Enriched Silk Fibroin for the Treatment of Orthopedic or Dental Infections

by Zili Sideratou, Marco Biagiotti, Dimitris Tsiourvas, Katerina N. Panagiotaki, Marta V. Zucca, Giuliano Freddi, Arianna B. Lovati and Marta Bottagisio

Nanomaterials 2022, 12(18), 3182; https://doi.org/10.3390/nano12183182 - 13 Sep 2022

Cited by 5 | Viewed by 2647

Abstract

The development of innovative osteoconductive matrices, which are enriched with antibiotic delivery nanosystems, has the invaluable potential to achieve both local contaminant eradication and the osseointegration of implanted devices. With the aim of producing safe, bioactive materials that have osteoconductive and antibacterial properties, [...] Read more.

The development of innovative osteoconductive matrices, which are enriched with antibiotic delivery nanosystems, has the invaluable potential to achieve both local contaminant eradication and the osseointegration of implanted devices. With the aim of producing safe, bioactive materials that have osteoconductive and antibacterial properties, novel, antibiotic-loaded, functionalized nanoparticles (AFN)—based on carboxylic acid functionalized hyperbranched aliphatic polyester (CHAP) that can be integrated into peptide-enriched silk fibroin (PSF) matrices with osteoconductive properties—were successfully synthesized. The obtained AFNPSF sponges were first physico-chemically characterized and then tested in vitro against eukaryotic cells and bacteria involved in orthopedic or oral infections. The biocompatibility and microbiological tests confirmed the promising characteristics of the AFN-PSF products for both orthopedic and dental applications. These preliminary results encourage the establishment of AFN-PSF-based preventative strategies in the fight against implant-related infections. Full article

(This article belongs to the Special Issue Nanostructured Materials for Biological and Pharmaceutical Applications)

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