Nanomaterials

11 pages, 577 KiB

Open AccessEditor’s ChoiceArticle

Analytical Performance and Validation of a Reliable Method Based on Graphite Furnace Atomic Absorption Spectrometry for the Determination of Gold Nanoparticles in Biological Tissues

by Oana Cadar, Teodora Mocan, Cecilia Roman and Marin Senila

Nanomaterials 2021, 11(12), 3370; https://doi.org/10.3390/nano11123370 - 12 Dec 2021

Cited by 8 | Viewed by 3088

Abstract

Gold nanoparticles (AuNPs) have a wide-ranging application and are widespread in samples with complex matrices; thus, efficient analytical procedures are necessary to identify and characterize this analyte. A sensitive analytical method for determination of AuNPs content in biological tissues, based on microwave-assisted acid [...] Read more.

Gold nanoparticles (AuNPs) have a wide-ranging application and are widespread in samples with complex matrices; thus, efficient analytical procedures are necessary to identify and characterize this analyte. A sensitive analytical method for determination of AuNPs content in biological tissues, based on microwave-assisted acid wet digestion and graphite furnace atomic absorption spectrometry (GFAAS) validated in accordance with the requirements of Eurachem guideline and ISO 17025 standard, is presented in this study. The digestion procedure was optimized, and the figures of merit such as selectivity, limit of detection (0.43 µg L⁻¹), limit of quantification (1.29 µg L⁻¹, corresponding to 12.9 µg kg⁻¹ in tissue sample, considering the digestion), working range, linearity, repeatability ((RSD_r 4.15%), intermediate precision (RSD_R 8.07%), recovery in accuracy study (97%), were methodically evaluated. The measurement uncertainty was assessed considering the main sources of uncertainties and the calculated relative expanded uncertainty (k = 2) was 12.5%. The method was applied for the determination of AuNPs in six biological tissues (liver, small intestine, heart, lungs, brain and kidneys) and the found concentrations were generally at low levels, close or lower than LOQ. Full article

(This article belongs to the Special Issue Theranostic Nanomedicine and Nanomaterials)

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11 pages, 2376 KiB

Open AccessEditor’s ChoiceArticle

Cation Crosslinking-Induced Stable Copper Nanoclusters Powder as Latent Fingerprints Marker

by Yi Qiu, Zhuoqi Wen, Shiliang Mei, Jinxin Wei, Yuanyuan Chen, Zhe Hu, Zhongjie Cui, Wanlu Zhang, Fengxian Xie and Ruiqian Guo

Nanomaterials 2021, 11(12), 3371; https://doi.org/10.3390/nano11123371 - 12 Dec 2021

Cited by 4 | Viewed by 3193

Abstract

Luminescent copper nanoclusters (Cu NCs) have shown great potential in light-emitting devices (LEDs), chemical sensing, catalysis and biological fields. However, their practical use has been restricted by poor stability, and study on the stability of Cu NCs solid powder along with the mechanism [...] Read more.

Luminescent copper nanoclusters (Cu NCs) have shown great potential in light-emitting devices (LEDs), chemical sensing, catalysis and biological fields. However, their practical use has been restricted by poor stability, and study on the stability of Cu NCs solid powder along with the mechanism is absent. In this study, stablized Cu NCs powder was first obtained by cation crosslinking method. Compared with the powder synthesized by solvent precipitation method, the stability of Cu NCs powder crosslinked by ionic inducer Ce³⁺ was enhanced around 100-fold. The storage time when the fluorescence intensity decreased to 85% (T₈₅) was improved from 2 h to 216 h, which is the longest so far. The results of characterizations indicated that the aggregation structure was formed by the binding of Ce³⁺ with the capping ligands of Cu NCs, which helped in obtaining Ce-Cu NCs powder from aggregate precipitation in solution. Furthermore, this compact structure could avoid the destruction of ambient moisture resulting in long-lasting fluorescence and almost unchanged physical form. This demonstrated that phosphor, with excellent characteristics of unsophisticated synthesis, easy preservation and stable fluorescence, showed great potential in light sources, display technology and especially in latent fingerprints visualization on different substrates for forensic science. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Nanoparticles with Luminescence Properties)

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13 pages, 3446 KiB

Open AccessEditor’s ChoiceArticle

Facile Fabrication of Single-Walled Carbon Nanotube/Anatase Composite Thin Film on Quartz Glass Substrate for Translucent Conductive Photoelectrode

by Yutaka Suwazono, Takuro Murayoshi, Hiroki Nagai and Mitsunobu Sato

Nanomaterials 2021, 11(12), 3352; https://doi.org/10.3390/nano11123352 - 10 Dec 2021

Cited by 4 | Viewed by 2650

Abstract

A single-walled carbon nanotube/anatase (SWCNT/anatase) composite thin film with a transmittance of over 70% in the visible-light region was fabricated on a quartz glass substrate by heat treating a precursor film at 500 °C in air. The precursor film was formed by spin [...] Read more.

A single-walled carbon nanotube/anatase (SWCNT/anatase) composite thin film with a transmittance of over 70% in the visible-light region was fabricated on a quartz glass substrate by heat treating a precursor film at 500 °C in air. The precursor film was formed by spin coating a mixed solution of the titania molecular precursor and well-dispersed SWCNTs (0.075 mass%) in ethanol. The anatase crystals and Ti³⁺ ions in the composite thin films were determined by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The effect of the heating process on the SWCNTs was analyzed using Raman spectroscopy. The composite film showed an even surface with a scratch resistance of 4H pencil hardness, as observed using field-emission scanning electron microscopy and atomic force microscopy. The electrical resistivity and optical bandgap energy of the composite thin film with a thickness of 100 nm were 6.6 × 10⁻² Ω cm and 3.4 eV, respectively, when the SWCNT content in the composite thin film was 2.9 mass%. An anodic photocurrent density of 4.2 μA cm⁻² was observed under ultraviolet light irradiation (16 mW cm⁻² at 365 nm) onto the composite thin film, thus showing excellent properties as a photoelectrode without conductive substrates. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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16 pages, 4430 KiB

Open AccessEditor’s ChoiceArticle

Structural and Surfacial Modification of Carbon Nanofoam as an Interlayer for Electrochemically Stable Lithium-Sulfur Cells

by Yee-Jun Quay and Sheng-Heng Chung

Nanomaterials 2021, 11(12), 3342; https://doi.org/10.3390/nano11123342 - 9 Dec 2021

Cited by 12 | Viewed by 3179

Abstract

Electrochemical lithium-sulfur batteries engage the attention of researchers due to their high-capacity sulfur cathodes, which meet the increasing energy-density needs of next-generation energy-storage systems. We present here the design, modification, and investigation of a carbon nanofoam as the interlayer in a lithium-sulfur cell [...] Read more.

Electrochemical lithium-sulfur batteries engage the attention of researchers due to their high-capacity sulfur cathodes, which meet the increasing energy-density needs of next-generation energy-storage systems. We present here the design, modification, and investigation of a carbon nanofoam as the interlayer in a lithium-sulfur cell to enable its high-loading sulfur cathode to attain high electrochemical utilization, efficiency, and stability. The carbon-nanofoam interlayer features a porous and tortuous carbon network that accelerates the charge transfer while decelerating the polysulfide diffusion. The improved cell demonstrates a high electrochemical utilization of over 80% and an enhanced stability of 200 cycles. With such a high-performance cell configuration, we investigate how the battery chemistry is affected by an additional polysulfide-trapping MoS₂ layer and an additional electron-transferring graphene layer on the interlayer. Our results confirm that the cell-configuration modification brings major benefits to the development of a high-loading sulfur cathode for excellent electrochemical performances. We further demonstrate a high-loading cathode with the carbon-nanofoam interlayer, which attains a high sulfur loading of 8 mg cm⁻², an excellent areal capacity of 8.7 mAh cm⁻², and a superior energy density of 18.7 mWh cm⁻² at a low electrolyte-to-sulfur ratio of 10 µL mg⁻¹. Full article

(This article belongs to the Special Issue State-of-the-Art Nanomaterials for Energy Storage/Conversion and Electrocatalysis in Taiwan)

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14 pages, 5344 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Direct Plasmonic Solar Cell Efficiency Dependence on Spiro-OMeTAD Li-TFSI Content

by Xinjian Geng, Mohamed Abdellah, Robert Bericat Vadell, Matilda Folkenant, Tomas Edvinsson and Jacinto Sá

Nanomaterials 2021, 11(12), 3329; https://doi.org/10.3390/nano11123329 - 8 Dec 2021

Cited by 10 | Viewed by 3944

Abstract

The proliferation of the internet of things (IoT) and other low-power devices demands the development of energy harvesting solutions to alleviate IoT hardware dependence on single-use batteries, making their deployment more sustainable. The propagation of energy harvesting solutions is strongly associated with technical [...] Read more.

The proliferation of the internet of things (IoT) and other low-power devices demands the development of energy harvesting solutions to alleviate IoT hardware dependence on single-use batteries, making their deployment more sustainable. The propagation of energy harvesting solutions is strongly associated with technical performance, cost and aesthetics, with the latter often being the driver of adoption. The general abundance of light in the vicinity of IoT devices under their main operation window enables the use of indoor and outdoor photovoltaics as energy harvesters. From those, highly transparent solar cells allow an increased possibility to place a sustainable power source close to the sensors without significant visual appearance. Herein, we report the effect of hole transport layer Li-TFSI dopant content on semi-transparent, direct plasmonic solar cells (DPSC) with a transparency of more than 80% in the 450–800 nm region. The findings revealed that the amount of oxidized spiro-OMeTAD (spiro⁺TFSI⁻) significantly modulates the transparency, effective conductance and conditions of device performance, with an optimal performance reached at around 33% relative concentration of Li-TFSI concerning spiro-OMeTAD. The Li-TFSI content did not affect the immediate charge extraction, as revealed by an analysis of electron–phonon lifetime. Hot electrons and holes were injected into the respective layers within 150 fs, suggesting simultaneous injection, as supported by the absence of hysteresis in the I–V curves. The spiro-OMeTAD layer reduces the Au nanoparticles’ reflection/backscattering, which improves the overall cell transparency. The results show that the system can be made highly transparent by precise tuning of the doping level of the spiro-OMeTAD layer with retained plasmonics, large optical cross-sections and the ultrathin nature of the devices. Full article

(This article belongs to the Special Issue Nanostructured Materials for Photonics and Plasmonics)

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12 pages, 5082 KiB

Open AccessEditor’s ChoiceArticle

Aptamer Conjugated Indium Phosphide Quantum Dots with a Zinc Sulphide Shell as Photoluminescent Labels for Acinetobacter baumannii

by Zeineb Ayed, Shiana Malhotra, Garima Dobhal and Renee V. Goreham

Nanomaterials 2021, 11(12), 3317; https://doi.org/10.3390/nano11123317 - 7 Dec 2021

Cited by 15 | Viewed by 4190

Abstract

Acinetobacter baumannii is a remarkable microorganism known for its diversity of habitat and its multi-drug resistance, resulting in hard-to-treat infections. Thus, a sensitive method for the identification and detection of Acinetobacter baumannii is vital. However, current methods used for the detection of pathogens [...] Read more.

Acinetobacter baumannii is a remarkable microorganism known for its diversity of habitat and its multi-drug resistance, resulting in hard-to-treat infections. Thus, a sensitive method for the identification and detection of Acinetobacter baumannii is vital. However, current methods used for the detection of pathogens have not improved in the past decades and suffer from long process times and low detection limits. A cheap, quick, and easy detection mechanism is needed. In this work, we successfully prepared indium phosphide quantum dots with a zinc sulphide shell, conjugated to a targeting aptamer ligand, to specifically label Acinetobacter baumannii. The system retained both the photophysical properties of the quantum dots and the folded structure and molecular recognition function of the aptamer, therefore successfully targeting Acinetobacter baumannii. Confocal microscopy and transmission electron microscopy showed the fluorescent quantum dots surrounding the Acinetobacter baumannii cells confirming the specificity of the aptamer conjugated to indium phosphide quantum dots with a zinc sulphide shell. Controls were undertaken with a different bacteria species, showing no binding of the aptamer conjugated quantum dots. Our strategy offers a novel method to detect bacteria and engineer a scalable platform for fluorescence detection, therefore improving current methods and allowing for better treatment. Full article

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8 pages, 1795 KiB

Open AccessEditor’s ChoiceArticle

Band Structure and Energy Level Alignment of Chiral Graphene Nanoribbons on Silver Surfaces

by Martina Corso, Rodrigo E. Menchón, Ignacio Piquero-Zulaica, Manuel Vilas-Varela, J. Enrique Ortega, Diego Peña, Aran Garcia-Lekue and Dimas G. de Oteyza

Nanomaterials 2021, 11(12), 3303; https://doi.org/10.3390/nano11123303 - 6 Dec 2021

Cited by 5 | Viewed by 3942

Abstract

Chiral graphene nanoribbons are extremely interesting structures due to their narrow band gaps and potential development of spin-polarized edge states. Here, we study their band structure on low work function silver surfaces. The use of a curved Ag single crystal provides, within the [...] Read more.

Chiral graphene nanoribbons are extremely interesting structures due to their narrow band gaps and potential development of spin-polarized edge states. Here, we study their band structure on low work function silver surfaces. The use of a curved Ag single crystal provides, within the same sample, regions of disparate step structure and step density. Whereas the former leads to distinct azimuthal growth orientations of the graphene nanoribbons atop, the latter modulates the substrate’s work function and thereby the interface energy level alignment. In turn, we disclose the associated charge transfer from the substrate to the ribbon and assess its effect on the nanoribbon’s properties and the edge state magnetization. Full article

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

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29 pages, 5883 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Quantitative Assessment of Chirality of Protein Secondary Structures and Phenylalanine Peptide Nanotubes

by Alla Sidorova, Vladimir Bystrov, Aleksey Lutsenko, Denis Shpigun, Ekaterina Belova and Ilya Likhachev

Nanomaterials 2021, 11(12), 3299; https://doi.org/10.3390/nano11123299 - 5 Dec 2021

Cited by 15 | Viewed by 2763

Abstract

In this study we consider the features of spatial-structure formation in proteins and their application in bioengineering. Methods for the quantitative assessment of the chirality of regular helical and irregular structures of proteins are presented. The features of self-assembly of phenylalanine (F) into [...] Read more.

In this study we consider the features of spatial-structure formation in proteins and their application in bioengineering. Methods for the quantitative assessment of the chirality of regular helical and irregular structures of proteins are presented. The features of self-assembly of phenylalanine (F) into peptide nanotubes (PNT), which form helices of different chirality, are also analyzed. A method is proposed for calculating the magnitude and sign of the chirality of helix-like peptide nanotubes using a sequence of vectors for the dipole moments of individual peptides. Full article

(This article belongs to the Special Issue Simulation and Modeling of Nanomaterials)

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15 pages, 2793 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparison of Different Commercial Nanopolystyrenes: Behavior in Exposure Media, Effects on Immune Function and Early Larval Development in the Model Bivalve Mytilus galloprovincialis

by Manon Auguste, Teresa Balbi, Angelica Miglioli, Stefano Alberti, Sonja Prandi, Riccardo Narizzano, Annalisa Salis, Gianluca Damonte and Laura Canesi

Nanomaterials 2021, 11(12), 3291; https://doi.org/10.3390/nano11123291 - 4 Dec 2021

Cited by 12 | Viewed by 2608

Abstract

In the absence of standard methods for the detection/quantification of nanoplastics (NPs) in environmental samples, commercial nanopolymers are utilized as proxies for toxicity testing and environmental risk assessment. In marine species, a considerable amount of data are now available on the effects of [...] Read more.

In the absence of standard methods for the detection/quantification of nanoplastics (NPs) in environmental samples, commercial nanopolymers are utilized as proxies for toxicity testing and environmental risk assessment. In marine species, a considerable amount of data are now available on the effects of nanopolystyrene (PS-NPs) of different size/surface characteristics. In this work, amino modified PS-NPs (PS-NH₂) (50 and 100 nm), purchased from two different companies, were compared in terms of behavior in exposure media and of biological responses, from molecular to organism level, in the model marine bivalve Mytilus. Different PS-NH₂ showed distinct agglomeration and surface charge in artificial sea water (ASW) and hemolymph serum (HS). Differences in behavior were largely reflected by the effects on immune function in vitro and in vivo and on early larval development. Stronger effects were generally observed with PS-NH₂ of smaller size, showing less agglomeration and higher positive charge in exposure media. Specific molecular interactions with HS components were investigated by the isolation and characterization of the NP-corona proteins. Data obtained in larvae demonstrate interference with the molecular mechanisms of shell biogenesis. Overall, different PS-NH₂ can affect the key physiological functions of mussels at environmental concentrations (10 µg/L). However, detailed information on the commercial NPs utilized is required to compare their biological effects among laboratory experiments. Full article

(This article belongs to the Special Issue Do Nanoplastics Represent a Risk for Aquatic Organisms? From Bio-Nano-Interactions to Possible Impacts at Population and Community Level)

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9 pages, 2579 KiB

Open AccessEditor’s ChoiceArticle

The Applications of Ultra-Thin Nanofilm for Aerospace Advanced Manufacturing Technology

by Guibai Xie, Hongwu Bai, Guanghui Miao, Guobao Feng, Jing Yang, Yun He, Xiaojun Li and Yun Li

Nanomaterials 2021, 11(12), 3282; https://doi.org/10.3390/nano11123282 - 3 Dec 2021

Cited by 17 | Viewed by 3099

Abstract

With the development of industrial civilization, advanced manufacturing technology has attracted widespread concern, including in the aerospace industry. In this paper, we report the applications of ultra-thin atomic layer deposition nanofilm in the advanced aerospace manufacturing industry, including aluminum anti-oxidation and secondary electron [...] Read more.

With the development of industrial civilization, advanced manufacturing technology has attracted widespread concern, including in the aerospace industry. In this paper, we report the applications of ultra-thin atomic layer deposition nanofilm in the advanced aerospace manufacturing industry, including aluminum anti-oxidation and secondary electron suppression, which are critical in high-power and miniaturization development. The compact and uniform aluminum oxide film, which is formed by thermal atomic layer deposition (ALD), can prevent the deep surface oxidation of aluminum during storage, avoiding the waste of material and energy in repetitive production. The total secondary electron yield of the C/TiN component nanofilm, deposited through plasma-enhanced atomic layer deposition, decreases 25% compared with an uncoated surface. The suppression of secondary electron emission is of great importance in solving the multipactor for high-power microwave components in space. Moreover, the controllable, ultra-thin uniform composite nanofilm can be deposited directly on the complex surface of devices without any transfer process, which is critical for many different applications. The ALD nanofilm shows potential for promoting system performance and resource consumption in the advanced aerospace manufacturing industry. Full article

(This article belongs to the Special Issue Nanomaterials for Membranes, Membrane Reactors and Catalyst Systems)

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20 pages, 5332 KiB

Open AccessEditor’s ChoiceArticle

Extra-Low Dosage Graphene Oxide Cementitious Nanocomposites: A Nano- to Macroscale Approach

by Mehdi Chougan, Francesca Romana Lamastra, Eleonora Bolli, Daniela Caschera, Saulius Kaciulis, Claudia Mazzuca, Giampiero Montesperelli, Seyed Hamidreza Ghaffar, Mazen J. Al-Kheetan and Alessandra Bianco

Nanomaterials 2021, 11(12), 3278; https://doi.org/10.3390/nano11123278 - 2 Dec 2021

Cited by 14 | Viewed by 2939

Abstract

The impact of extra-low dosage (0.01% by weight of cement) Graphene Oxide (GO) on the properties of fresh and hardened nanocomposites was assessed. The use of a minimum amount of 2-D nanofiller would minimize costs and sustainability issues, therefore encouraging the market uptake [...] Read more.

The impact of extra-low dosage (0.01% by weight of cement) Graphene Oxide (GO) on the properties of fresh and hardened nanocomposites was assessed. The use of a minimum amount of 2-D nanofiller would minimize costs and sustainability issues, therefore encouraging the market uptake of nanoengineered cement-based materials. GO was characterized by X-ray Photoelectron Spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), and Raman spectroscopy. GO consisted of stacked sheets up to 600 nm × 800 nm wide and 2 nm thick, oxygen content 31 at%. The impact of GO on the fresh admixtures was evaluated by rheology, flowability, and workability measurements. GO-modified samples were characterized by density measurements, Scanning Electron Microscopy (SEM) analysis, and compression and bending tests. Permeability was investigated using the boiling-water saturation technique, salt ponding test, and Initial Surface Absorption Test (ISAT). At 28 days, GO-nanocomposite exhibited increased density (+14%), improved compressive and flexural strength (+29% and +13%, respectively), and decreased permeability compared to the control sample. The strengthening effect dominated over the adverse effects associated with the worsening of the fresh properties; reduced permeability was mainly attributed to the refining of the pore network induced by the presence of GO. Full article

(This article belongs to the Special Issue Smart Cementitious Materials for Sustainable Building Engineering)

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9 pages, 1300 KiB

Open AccessEditor’s ChoiceArticle

The High Coercivity Field in Chemically Bonded WSe₂/MoSe₂ Powder

by Shiu-Ming Huang, Pin-Cyuan Chen and Pin-Cing Wang

Nanomaterials 2021, 11(12), 3263; https://doi.org/10.3390/nano11123263 - 1 Dec 2021

Cited by 3 | Viewed by 2493

Abstract

We studied the magnetic properties of WSe

_{2}

/MoSe

_{2}

powder. The coercivity field reaches 2600 Oe at 5 K, 4233 Oe at 100 K and 1300 Oe at 300 K. These are the highest values reported for two-dimensional transition metal dichalcogenides. This [...] Read more.

We studied the magnetic properties of WSe

_{2}

/MoSe

_{2}

powder. The coercivity field reaches 2600 Oe at 5 K, 4233 Oe at 100 K and 1300 Oe at 300 K. These are the highest values reported for two-dimensional transition metal dichalcogenides. This study is different from the widely reported vacancy and zigzag structure-induced ferromagnetism studies. Importantly, a Raman peak red shift was observed, and that supports the chemical bonding at the interface between WSe

_{2}

and MoSe

_{2}

. The large coercivity field originates from the chemical bonding-induced structural distortion at the interface between WSe

_{2}

and MoSe

_{2}

. Full article

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

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10 pages, 1169 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Gold Nanostars Embedded in PDMS Films: A Photothermal Material for Antibacterial Applications

by Gemma Toci, Francesca Olgiati, Piersandro Pallavicini, Yuri Antonio Diaz Fernandez, Lorenzo De Vita, Giacomo Dacarro, Pietro Grisoli and Angelo Taglietti

Nanomaterials 2021, 11(12), 3252; https://doi.org/10.3390/nano11123252 - 30 Nov 2021

Cited by 18 | Viewed by 3313

Abstract

Bacteria infections and related biofilms growth on surfaces of medical devices are a serious threat to human health. Controlled hyperthermia caused by photothermal effects can be used to kill bacteria and counteract biofilms formation. Embedding of plasmonic nano-objects like gold nanostars (GNS), able [...] Read more.

Bacteria infections and related biofilms growth on surfaces of medical devices are a serious threat to human health. Controlled hyperthermia caused by photothermal effects can be used to kill bacteria and counteract biofilms formation. Embedding of plasmonic nano-objects like gold nanostars (GNS), able to give an intense photothermal effect when irradiated in the NIR, can be a smart way to functionalize a transparent and biocompatible material like polydimethylsiloxane (PDMS). This process enables bacteria destruction on surfaces of PDMS-made medical surfaces, an action which, in principle, can also be exploited in subcutaneous devices. We prepared stable and reproducible thin PDMS films containing controllable quantities of GNS, enabling a temperature increase that can reach more than 40 degrees. The hyperthermia exerted by this hybrid material generates an effective thermal microbicidal effect, killing bacteria with a near infrared (NIR) laser source with irradiance values that are safe for skin. Full article

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

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13 pages, 4084 KiB

Open AccessEditor’s ChoiceArticle

Nanocone-Shaped Carbon Nanotubes Field-Emitter Array Fabricated by Laser Ablation

by Jiuzhou Zhao, Zhenjun Li, Matthew Thomas Cole, Aiwei Wang, Xiangdong Guo, Xinchuan Liu, Wei Lyu, Hanchao Teng, Yunpeng Qv, Guanjiang Liu, Ke Chen, Shenghan Zhou, Jianfeng Xiao, Yi Li, Chi Li and Qing Dai

Nanomaterials 2021, 11(12), 3244; https://doi.org/10.3390/nano11123244 - 29 Nov 2021

Cited by 15 | Viewed by 2960

Abstract

The nanocone-shaped carbon nanotubes field-emitter array (NCNA) is a near-ideal field-emitter array that combines the advantages of geometry and material. In contrast to previous methods of field-emitter array, laser ablation is a low-cost and clean method that does not require any photolithography or [...] Read more.

The nanocone-shaped carbon nanotubes field-emitter array (NCNA) is a near-ideal field-emitter array that combines the advantages of geometry and material. In contrast to previous methods of field-emitter array, laser ablation is a low-cost and clean method that does not require any photolithography or wet chemistry. However, nanocone shapes are hard to achieve through laser ablation due to the micrometer-scale focusing spot. Here, we develop an ultraviolet (UV) laser beam patterning technique that is capable of reliably realizing NCNA with a cone-tip radius of ≈300 nm, utilizing optimized beam focusing and unique carbon nanotube–light interaction properties. The patterned array provided smaller turn-on fields (reduced from 2.6 to 1.6 V/μm) in emitters and supported a higher (increased from 10 to 140 mA/cm²) and more stable emission than their unpatterned counterparts. The present technique may be widely applied in the fabrication of high-performance CNTs field-emitter arrays. Full article

(This article belongs to the Special Issue The Research Related to Nanomaterial Cold Cathode)

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16 pages, 9804 KiB

Open AccessEditor’s ChoiceArticle

Amorphous MoS_xO_y/h-BN_xO_y Nanohybrids: Synthesis and Dye Photodegradation

by Andrei T. Matveev, Anton S. Konopatsky, Denis V. Leybo, Ilia N. Volkov, Andrey M. Kovalskii, Liubov A. Varlamova, Pavel B. Sorokin, Xiaosheng Fang, Sergei A. Kulinich and Dmitry V. Shtansky

Nanomaterials 2021, 11(12), 3232; https://doi.org/10.3390/nano11123232 - 28 Nov 2021

Cited by 8 | Viewed by 3004

Abstract

Molybdenum sulfide is a very promising catalyst for the photodegradation of organic pollutants in water. Its photocatalytic activity arises from unsaturated sulfur bonds, and it increases with the introduction of structural defects and/or oxygen substitutions. Amorphous molybdenum sulfide (a-MoS_xO [...] Read more.

Molybdenum sulfide is a very promising catalyst for the photodegradation of organic pollutants in water. Its photocatalytic activity arises from unsaturated sulfur bonds, and it increases with the introduction of structural defects and/or oxygen substitutions. Amorphous molybdenum sulfide (a-MoS_xO_y) with oxygen substitutions has many active sites, which create favorable conditions for enhanced catalytic activity. Here we present a new approach to the synthesis of a-MoS_xO_y and demonstrate its high activity in the photodegradation of the dye methylene blue (MB). The MoS_xO_y was deposited on hexagonal boron oxynitride (h-BNO) nanoflakes by reacting h-BNO, MoCl₅, and H₂S in dimethylformamide (DMF) at 250 °C. Both X-ray diffraction analysis and high-resolution TEM show the absence of crystalline order in a-MoS_xO_y. Based on the results of Raman and X-ray photoelectron spectroscopy, as well as analysis by the density functional theory (DFT) method, a chain structure of a-MoS_xO_y was proposed, consisting of MoS₃ clusters with partial substitution of sulfur by oxygen. When a third of the sulfur atoms are replaced with oxygen, the band gap of a-MoS_xO_y is approximately 1.36 eV, and the valence and conduction bands are 0.74 eV and −0.62 eV, respectively (relative to a standard hydrogen electrode), which satisfies the conditions of photoinduced splitting of water. When illuminated with a mercury lamp, a-MoS_xO_y/h-BN_xO_y nanohybrids have a specific mass activity in MB photodegradation of approximately 5.51 mmol g⁻¹ h⁻¹, which is at least four times higher than so far reported values for nonmetal catalysts. The photocatalyst has been shown to be very stable and can be reused. Full article

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19 pages, 3238 KiB

Open AccessEditor’s ChoiceArticle

In Vitro Toxicity of Industrially Relevant Engineered Nanoparticles in Human Alveolar Epithelial Cells: Air–Liquid Interface versus Submerged Cultures

by Maria João Bessa, Fátima Brandão, Paul H. B. Fokkens, Daan L. A. C. Leseman, A. John F. Boere, Flemming R. Cassee, Apostolos Salmatonidis, Mar Viana, Adriana Vulpoi, Simion Simon, Eliseo Monfort, João Paulo Teixeira and Sónia Fraga

Nanomaterials 2021, 11(12), 3225; https://doi.org/10.3390/nano11123225 - 27 Nov 2021

Cited by 17 | Viewed by 3288

Abstract

Diverse industries have already incorporated within their production processes engineered nanoparticles (ENP), increasing the potential risk of worker inhalation exposure. In vitro models have been widely used to investigate ENP toxicity. Air–liquid interface (ALI) cell cultures have been emerging as a valuable alternative [...] Read more.

Diverse industries have already incorporated within their production processes engineered nanoparticles (ENP), increasing the potential risk of worker inhalation exposure. In vitro models have been widely used to investigate ENP toxicity. Air–liquid interface (ALI) cell cultures have been emerging as a valuable alternative to submerged cultures as they are more representative of the inhalation exposure to airborne nano-sized particles. We compared the in vitro toxicity of four ENP used as raw materials in the advanced ceramics sector in human alveolar epithelial-like cells cultured under submerged or ALI conditions. Submerged cultures were exposed to ENP liquid suspensions or to aerosolised ENP at ALI. Toxicity was assessed by determining LDH release, WST-1 metabolisation and DNA damage. Overall, cells were more sensitive to ENP cytotoxic effects when cultured and exposed under ALI. No significant cytotoxicity was observed after 24 h exposure to ENP liquid suspensions, although aerosolised ENP clearly affected cell viability and LDH release. In general, all ENP increased primary DNA damage regardless of the exposure mode, where an increase in DNA strand-breaks was only detected under submerged conditions. Our data show that at relevant occupational concentrations, the selected ENP exert mild toxicity to alveolar epithelial cells and exposure at ALI might be the most suitable choice when assessing ENP toxicity in respiratory models under realistic exposure conditions. Full article

(This article belongs to the Special Issue Engineered Nanomaterials Exposure and Risk Assessment: Occupational Health and Safety)

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8 pages, 2220 KiB

Open AccessEditor’s ChoiceArticle

One-Step Solution Deposition of Antimony Selenoiodide Films via Precursor Engineering for Lead-Free Solar Cell Applications

by Yong Chan Choi and Kang-Won Jung

Nanomaterials 2021, 11(12), 3206; https://doi.org/10.3390/nano11123206 - 26 Nov 2021

Cited by 12 | Viewed by 2910

Abstract

Ternary chalcohalides are promising lead-free photovoltaic materials with excellent optoelectronic properties. We propose a simple one-step solution-phase precursor-engineering method for antimony selenoiodide (SbSeI) film fabrication. SbSeI films were fabricated by spin-coating the precursor solution, and heating. Various precursor solutions were synthesized by adjusting [...] Read more.

Ternary chalcohalides are promising lead-free photovoltaic materials with excellent optoelectronic properties. We propose a simple one-step solution-phase precursor-engineering method for antimony selenoiodide (SbSeI) film fabrication. SbSeI films were fabricated by spin-coating the precursor solution, and heating. Various precursor solutions were synthesized by adjusting the molar ratio of two solutions based on SbCl₃-selenourea and SbI₃. The results suggest that both the molar ratio and the heating temperature play key roles in film phase and morphology. Nanostructured SbSeI films with a high crystallinity were obtained at a molar ratio of 1:1.5 and a temperature of 150 °C. The proposed method could be also used to fabricate (Bi,Sb)SeI. Full article

(This article belongs to the Special Issue Advances in Nanomaterials for Photovoltaic Applications)

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15 pages, 4159 KiB

Open AccessEditor’s ChoiceArticle

Examining the Transmission of Visible Light through Electrospun Nanofibrous PCL Scaffolds for Corneal Tissue Engineering

by Marcus Himmler, Dirk W. Schubert and Thomas A. Fuchsluger

Nanomaterials 2021, 11(12), 3191; https://doi.org/10.3390/nano11123191 - 25 Nov 2021

Cited by 12 | Viewed by 2825

Abstract

The transparency of nanofibrous scaffolds is of highest interest for potential applications like corneal wound dressings in corneal tissue engineering. In this study, we provide a detailed analysis of light transmission through electrospun polycaprolactone (PCL) scaffolds. PCL scaffolds were produced via electrospinning, with [...] Read more.

The transparency of nanofibrous scaffolds is of highest interest for potential applications like corneal wound dressings in corneal tissue engineering. In this study, we provide a detailed analysis of light transmission through electrospun polycaprolactone (PCL) scaffolds. PCL scaffolds were produced via electrospinning, with fiber diameters in the range from (35 ± 13) nm to (167 ± 35) nm. Light transmission measurements were conducted using UV–vis spectroscopy in the range of visible light and analyzed with respect to the influence of scaffold thickness, fiber diameter, and surrounding medium. Contour plots were compiled for a straightforward access to light transmission values for arbitrary scaffold thicknesses. Depending on the fiber diameter, transmission values between 15% and 75% were observed for scaffold thicknesses of 10 µm. With a decreasing fiber diameter, light transmission could be improved, as well as with matching refractive indices of fiber material and medium. For corneal tissue engineering, scaffolds should be designed as thin as possible and fabricated from polymers with a matching refractive index to that of the human cornea. Concerning fiber diameter, smaller fiber diameters should be favored for maximizing graft transparency. Finally, a novel, semi-empirical formulation of light transmission through nanofibrous scaffolds is presented. Full article

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

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9 pages, 2614 KiB

Open AccessEditor’s ChoiceArticle

Bright Silicon Carbide Single-Photon Emitting Diodes at Low Temperatures: Toward Quantum Photonics Applications

by Igor A. Khramtsov and Dmitry Yu. Fedyanin

Nanomaterials 2021, 11(12), 3177; https://doi.org/10.3390/nano11123177 - 24 Nov 2021

Cited by 2 | Viewed by 2389

Abstract

Color centers in silicon carbide have recently emerged as one of the most promising emitters for bright single-photon emitting diodes (SPEDs). It has been shown that, at room temperature, they can emit more than 10⁹ photons per second under electrical excitation. However, [...] Read more.

Color centers in silicon carbide have recently emerged as one of the most promising emitters for bright single-photon emitting diodes (SPEDs). It has been shown that, at room temperature, they can emit more than 10⁹ photons per second under electrical excitation. However, the spectral emission properties of color centers in SiC at room temperature are far from ideal. The spectral properties could be significantly improved by decreasing the operating temperature. However, the densities of free charge carriers in SiC rapidly decrease as temperature decreases, which reduces the efficiency of electrical excitation of color centers by many orders of magnitude. Here, we study for the first time the temperature characteristics of SPEDs based on color centers in 4H-SiC. Using a rigorous numerical approach, we demonstrate that although the single-photon electroluminescence rate does rapidly decrease as temperature decreases, it is possible to increase the SPED brightness to 10⁷ photons/s at 100 K using the recently predicted effect of hole superinjection in homojunction p-i-n diodes. This gives the possibility to achieve high brightness and good spectral properties at the same time, which paves the way toward novel quantum photonics applications of electrically driven color centers in silicon carbide. Full article

(This article belongs to the Special Issue Advances in Silicon Carbide Nanomaterials)

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12 pages, 3965 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Morphological Studies of Composite Spin Crossover@SiO₂ Nanoparticles

by Yue Zan, Lionel Salmon and Azzedine Bousseksou

Nanomaterials 2021, 11(12), 3169; https://doi.org/10.3390/nano11123169 - 23 Nov 2021

Cited by 8 | Viewed by 2286

Abstract

Spin crossover (SCO) iron (II) 1,2,4-triazole-based coordination compounds in the form of composite SCO@SiO₂ nanoparticles were prepared using a reverse microemulsion technique. The thickness of the silica shell and the morphology of the as obtained core@shell nanoparticles were studied by modifying the [...] Read more.

Spin crossover (SCO) iron (II) 1,2,4-triazole-based coordination compounds in the form of composite SCO@SiO₂ nanoparticles were prepared using a reverse microemulsion technique. The thickness of the silica shell and the morphology of the as obtained core@shell nanoparticles were studied by modifying the polar phase/surfactant ratio (ω), as well as the quantity and the insertion phase (organic, aqueous and micellar phases) of the tetraethylorthosilicate (TEOS) precursor, the quantity of ammonia and the reaction temperature. The morphology of the nanoparticles was monitored by transmission electron microscopy (TEM/HRTEM) while their composition probed by combined elemental analyses, thermogravimetry and EDX analyses. We report that not only the particle size can be controlled but also the size of the silica shell, allowing for interesting perspectives in post-synthetic modification of the shell. The evolution of the spin crossover properties associated with the change in morphology was investigated by variable temperature optical and magnetic measurements. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)

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14 pages, 4003 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Novel Pastes Containing Polymeric Nanoparticles for Dentin Hypersensitivity Treatment: An In Vitro Study

by Manuel Toledano-Osorio, Raquel Osorio, Estrella Osorio, Antonio L. Medina-Castillo and Manuel Toledano

Nanomaterials 2021, 11(11), 3150; https://doi.org/10.3390/nano11113150 - 22 Nov 2021

Cited by 6 | Viewed by 2973

Abstract

Tubule occlusion and remineralization are considered the two main goals of dentin hypersensitivity treatment. The objective is to assess the ability of dentifrices containing zinc-doped polymeric nanoparticles (NPs) to enduringly occlude the dentinal tubules, reinforcing dentin’s mechanical properties. Fifteen dentin surfaces were acid-treated [...] Read more.

Tubule occlusion and remineralization are considered the two main goals of dentin hypersensitivity treatment. The objective is to assess the ability of dentifrices containing zinc-doped polymeric nanoparticles (NPs) to enduringly occlude the dentinal tubules, reinforcing dentin’s mechanical properties. Fifteen dentin surfaces were acid-treated for dentinal tubule exposure and brushed with (1) distilled water, or with experimental pastes containing (2) 1% of zinc-doped NPs, (3) 5% of zinc-doped NPs, (4) 10% of zinc-doped NPs or (5) Sensodyne^®. Topographical and nanomechanical analyses were performed on treated dentin surfaces and after a citric acid challenge. ANOVA and Student–Newman–Keuls tests were used (p < 0.05). The main results indicate that all pastes produced tubule occlusion (100%) and reinforced mechanical properties of intertubular dentin (complex modulus was above 75 GPa). After the citric acid challenge, only those pastes containing zinc-doped NPs were able to maintain tubular occlusion, as specimens treated with Sensodyne^® have around 30% of tubules opened. Mechanical properties were maintained for dentin treated with Zn-doped NPs, but in the case of specimens treated with Sensodyne^®, complex modulus values were reduced below 50 GPa. It may be concluded that zinc-doped NPs at the lowest tested concentration produced acid-resistant tubular occlusion and increased the mechanical properties of dentin. Full article

(This article belongs to the Special Issue Nanomaterials in Dentistry)

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10 pages, 2769 KiB

Open AccessEditor’s ChoiceArticle

Plasmonic Gold Nanoisland Film for Bacterial Theranostics

by Shih-Hua Tan, Sibidou Yougbaré, Hsuan-Ya Tao, Che-Chang Chang and Tsung-Rong Kuo

Nanomaterials 2021, 11(11), 3139; https://doi.org/10.3390/nano11113139 - 21 Nov 2021

Cited by 14 | Viewed by 2359

Abstract

Plasmonic nanomaterials have been intensively explored for applications in biomedical detection and therapy for human sustainability. Herein, plasmonic gold nanoisland (NI) film (AuNIF) was fabricated onto a glass substrate by a facile seed-mediated growth approach. The structure of the tortuous gold NIs of [...] Read more.

Plasmonic nanomaterials have been intensively explored for applications in biomedical detection and therapy for human sustainability. Herein, plasmonic gold nanoisland (NI) film (AuNIF) was fabricated onto a glass substrate by a facile seed-mediated growth approach. The structure of the tortuous gold NIs of the AuNIF was demonstrated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Based on the ultraviolet-visible spectrum, the AuNIF revealed plasmonic absorption with maximum intensity at 624 nm. With the change to the surface topography created by the NIs, the capture efficiency of Escherichia coli (E. coli) by the AuNIF was significantly increased compared to that of the glass substrate. The AuNIF was applied as a surface-enhanced Raman scattering (SERS) substrate to enhance the Raman signal of E. coli. Moreover, the plasmonic AuNIF exhibited a superior photothermal effect under irradiation with simulated AM1.5 sunlight. For photothermal therapy, the AuNIF also displayed outstanding efficiency in the photothermal killing of E. coli. Using a combination of SERS detection and photothermal therapy, the AuNIF could be a promising platform for bacterial theranostics. Full article

(This article belongs to the Special Issue Antibacterial Applications of Nanomaterials)

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37 pages, 3518 KiB

Open AccessEditor’s ChoiceReview

Nanoparticle Systems for Cancer Phototherapy: An Overview

by Thais P. Pivetta, Caroline E. A. Botteon, Paulo A. Ribeiro, Priscyla D. Marcato and Maria Raposo

Nanomaterials 2021, 11(11), 3132; https://doi.org/10.3390/nano11113132 - 20 Nov 2021

Cited by 54 | Viewed by 6153

Abstract

Photodynamic therapy (PDT) and photothermal therapy (PTT) are photo-mediated treatments with different mechanisms of action that can be addressed for cancer treatment. Both phototherapies are highly successful and barely or non-invasive types of treatment that have gained attention in the past few years. [...] Read more.

Photodynamic therapy (PDT) and photothermal therapy (PTT) are photo-mediated treatments with different mechanisms of action that can be addressed for cancer treatment. Both phototherapies are highly successful and barely or non-invasive types of treatment that have gained attention in the past few years. The death of cancer cells because of the application of these therapies is caused by the formation of reactive oxygen species, that leads to oxidative stress for the case of photodynamic therapy and the generation of heat for the case of photothermal therapies. The advancement of nanotechnology allowed significant benefit to these therapies using nanoparticles, allowing both tuning of the process and an increase of effectiveness. The encapsulation of drugs, development of the most different organic and inorganic nanoparticles as well as the possibility of surfaces’ functionalization are some strategies used to combine phototherapy and nanotechnology, with the aim of an effective treatment with minimal side effects. This article presents an overview on the use of nanostructures in association with phototherapy, in the view of cancer treatment. Full article

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

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13 pages, 3117 KiB

Open AccessEditor’s ChoiceArticle

Geometrical Nonlinearity for a Timoshenko Beam with Flexoelectricity

by Miroslav Repka, Jan Sladek and Vladimir Sladek

Nanomaterials 2021, 11(11), 3123; https://doi.org/10.3390/nano11113123 - 19 Nov 2021

Cited by 4 | Viewed by 2508

Abstract

The Timoshenko beam model is applied to the analysis of the flexoelectric effect for a cantilever beam under large deformations. The geometric nonlinearity with von Kármán strains is considered. The nonlinear system of ordinary differential equations (ODE) for beam deflection and rotation are [...] Read more.

The Timoshenko beam model is applied to the analysis of the flexoelectric effect for a cantilever beam under large deformations. The geometric nonlinearity with von Kármán strains is considered. The nonlinear system of ordinary differential equations (ODE) for beam deflection and rotation are derived. Moreover, this nonlinear system is linearized for each load increment, where it is solved iteratively. For the vanishing flexoelectric coefficient, the governing equations lead to the classical Timoshenko beam model. Furthermore, the influence of the flexoelectricity coefficient and the microstructural length-scale parameter on the beam deflection and the induced electric intensity is investigated. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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12 pages, 1737 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Anisotropic Optical and Vibrational Properties of GeS

by Natalia Zawadzka, Łucja Kipczak, Tomasz Woźniak, Katarzyna Olkowska-Pucko, Magdalena Grzeszczyk, Adam Babiński and Maciej R. Molas

Nanomaterials 2021, 11(11), 3109; https://doi.org/10.3390/nano11113109 - 18 Nov 2021

Cited by 15 | Viewed by 3070

Abstract

The optical response of bulk germanium sulfide (GeS) is investigated systematically using different polarization-resolved experimental techniques, such as photoluminescence (PL), reflectance contrast (RC), and Raman scattering (RS). It is shown that while the low-temperature (T = 5 K) optical band-gap absorption is [...] Read more.

The optical response of bulk germanium sulfide (GeS) is investigated systematically using different polarization-resolved experimental techniques, such as photoluminescence (PL), reflectance contrast (RC), and Raman scattering (RS). It is shown that while the low-temperature (T = 5 K) optical band-gap absorption is governed by a single resonance related to the neutral exciton, the corresponding emission is dominated by the disorder/impurity- and/or phonon-assisted recombination processes. Both the RC and PL spectra are found to be linearly polarized along the armchair direction. The measured RS spectra over a broad range from 5 to 300 K consist of six Raman peaks identified with the help of Density Functional Theory (DFT) calculations: A

_{g}^{1}

, A

_{g}^{2}

, A

_{g}^{3}

, A

_{g}^{4}

, B

_{1 g}^{1}

, and B

_{1 g}^{2}

, which polarization properties are studied under four different excitation energies. We found that the polarization orientations of the A

_{g}^{2}

and A

_{g}^{4}

modes under specific excitation energy can be useful tools to determine the GeS crystallographic directions: armchair and zigzag. Full article

(This article belongs to the Special Issue Excitons and Phonons in Two-Dimensional Materials: From Fundamental to Applications)

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19 pages, 8784 KiB

Open AccessEditor’s ChoiceArticle

Traceable Nanoscale Measurements of High Dielectric Constant by Scanning Microwave Microscopy

by Damien Richert, José Morán-Meza, Khaled Kaja, Alexandra Delvallée, Djamel Allal, Brice Gautier and François Piquemal

Nanomaterials 2021, 11(11), 3104; https://doi.org/10.3390/nano11113104 - 17 Nov 2021

Cited by 6 | Viewed by 2542

Abstract

The importance of high dielectric constant materials in the development of high frequency nano-electronic devices is undeniable. Their polarization properties are directly dependent on the value of their relative permittivity. We report here on the nanoscale metrological quantification of the dielectric constants of [...] Read more.

The importance of high dielectric constant materials in the development of high frequency nano-electronic devices is undeniable. Their polarization properties are directly dependent on the value of their relative permittivity. We report here on the nanoscale metrological quantification of the dielectric constants of two high-κ materials, lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT), in the GHz range using scanning microwave microscopy (SMM). We demonstrate the importance of the capacitance calibration procedure and dimensional measurements on the weight of the combined relative uncertainties. A novel approach is proposed to correct lateral dimension measurements of micro-capacitive structures using the microwave electrical signatures, especially for rough surfaces of high-κ materials. A new analytical expression is also given for the capacitance calculations, taking into account the contribution of fringing electric fields. We determine the dielectric constant values ε_PZT = 445 and ε_PMN-PT = 641 at the frequency around 3.6 GHz, with combined relative uncertainties of 3.5% and 6.9% for PZT and PMN-PT, respectively. This work provides a general description of the metrological path for a quantified measurement of high dielectric constants with well-controlled low uncertainty levels. Full article

(This article belongs to the Special Issue Nanometrology)

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35 pages, 11125 KiB

Open AccessEditor’s ChoiceReview

Physically Switchable Antimicrobial Surfaces and Coatings: General Concept and Recent Achievements

by Roman Elashnikov, Pavel Ulbrich, Barbora Vokatá, Vladimíra Svobodová Pavlíčková, Václav Švorčík, Oleksiy Lyutakov and Silvie Rimpelová

Nanomaterials 2021, 11(11), 3083; https://doi.org/10.3390/nano11113083 - 16 Nov 2021

Cited by 24 | Viewed by 3802

Abstract

Bacterial environmental colonization and subsequent biofilm formation on surfaces represents a significant and alarming problem in various fields, ranging from contamination of medical devices up to safe food packaging. Therefore, the development of surfaces resistant to bacterial colonization is a challenging and actively [...] Read more.

Bacterial environmental colonization and subsequent biofilm formation on surfaces represents a significant and alarming problem in various fields, ranging from contamination of medical devices up to safe food packaging. Therefore, the development of surfaces resistant to bacterial colonization is a challenging and actively solved task. In this field, the current promising direction is the design and creation of nanostructured smart surfaces with on-demand activated amicrobial protection. Various surface activation methods have been described recently. In this review article, we focused on the “physical” activation of nanostructured surfaces. In the first part of the review, we briefly describe the basic principles and common approaches of external stimulus application and surface activation, including the temperature-, light-, electric- or magnetic-field-based surface triggering, as well as mechanically induced surface antimicrobial protection. In the latter part, the recent achievements in the field of smart antimicrobial surfaces with physical activation are discussed, with special attention on multiresponsive or multifunctional physically activated coatings. In particular, we mainly discussed the multistimuli surface triggering, which ensures a better degree of surface properties control, as well as simultaneous utilization of several strategies for surface protection, based on a principally different mechanism of antimicrobial action. We also mentioned several recent trends, including the development of the to-detect and to-kill hybrid approach, which ensures the surface activation in a right place at a right time. Full article

(This article belongs to the Special Issue Biocompatibility of Nanomaterials in Medical Applications)

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12 pages, 2567 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Quantitative Estimation of Cell-Associated Silver Nanoparticles using the Normalized Side Scattering Intensities of Flow Cytometry

by Yoo Jin Shim, My Kieu Ha and Tae Hyun Yoon

Nanomaterials 2021, 11(11), 3079; https://doi.org/10.3390/nano11113079 - 15 Nov 2021

Cited by 5 | Viewed by 2392

Abstract

Quantification of cellular nanoparticles (NPs) is one of the most important steps in studying NP–cell interactions. Here, a simple method for the estimation of cell-associated silver (Ag) NPs in lung cancer cells (A549) is proposed based on their side scattering (SSC) intensities measured [...] Read more.

Quantification of cellular nanoparticles (NPs) is one of the most important steps in studying NP–cell interactions. Here, a simple method for the estimation of cell-associated silver (Ag) NPs in lung cancer cells (A549) is proposed based on their side scattering (SSC) intensities measured by flow cytometry (FCM). To estimate cellular Ag NPs associated with A549 cells over a broad range of experimental conditions, we measured the normalized SSC intensities (nSSC) of A549 cells treated with Ag NPs with five different core sizes (i.e., 40–200 nm, positively charged) under various exposure conditions that reflect different situations of agglomeration, diffusion, and sedimentation in cell culture media, such as upright and inverted configurations with different media heights. Then, we correlated these nSSC values with the numbers of cellular Ag NPs determined by inductively coupled plasma mass spectrometry (ICPMS) as a well-established cross-validation method. The different core sizes of Ag NPs and the various exposure conditions tested in this study confirmed that the FCM-SSC intensities are highly correlated with their core sizes as well as the amount of cellular Ag NPs over a linear range up to ~80,000 Ag NPs/cell and ~23 nSSC, which is significantly broader than those of previous studies. Full article

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

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30 pages, 6872 KiB

Open AccessEditor’s ChoiceArticle

Bioactivity of PEGylated Graphene Oxide Nanoparticles Combined with Near-Infrared Laser Irradiation Studied in Colorectal Carcinoma Cells

by Natalia Krasteva, Dessislava Staneva, Bela Vasileva, George Miloshev and Milena Georgieva

Nanomaterials 2021, 11(11), 3061; https://doi.org/10.3390/nano11113061 - 14 Nov 2021

Cited by 20 | Viewed by 2712

Abstract

Central focus in modern anticancer nanosystems is given to certain types of nanomaterials such as graphene oxide (GO). Its functionalization with polyethylene glycol (PEG) demonstrates high delivery efficiency and controllable release of proteins, bioimaging agents, chemotherapeutics and anticancer drugs. GO–PEG has a good [...] Read more.

Central focus in modern anticancer nanosystems is given to certain types of nanomaterials such as graphene oxide (GO). Its functionalization with polyethylene glycol (PEG) demonstrates high delivery efficiency and controllable release of proteins, bioimaging agents, chemotherapeutics and anticancer drugs. GO–PEG has a good biological safety profile, exhibits high NIR absorbance and capacity in photothermal treatment. To investigate the bioactivity of PEGylated GO NPs in combination with NIR irradiation on colorectal cancer cells we conducted experiments that aim to reveal the molecular mechanisms of action of this nanocarrier, combined with near-infrared light (NIR) on the high invasive Colon26 and the low invasive HT29 colon cancer cell lines. During reaching cancer cells the phototoxicity of GO–PEG is modulated by NIR laser irradiation. We observed that PEGylation of GO nanoparticles has well-pronounced biocompatibility toward colorectal carcinoma cells, besides their different malignant potential and treatment times. This biocompatibility is potentiated when GO–PEG treatment is combined with NIR irradiation, especially for cells cultured and treated for 24 h. The tested bioactivity of GO–PEG in combination with NIR irradiation induced little to no damages in DNA and did not influence the mitochondrial activity. Our findings demonstrate the potential of GO–PEG-based photoactivity as a nanosystem for colorectal cancer treatment. Full article

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

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12 pages, 4588 KiB

Open AccessEditor’s ChoiceArticle

Eliciting Specific Electrochemical Reaction Behavior by Rational Design of a Red Phosphorus Electrode for Sodium-Ion Batteries

by Jong Hyuk Yun, San Moon, Do Kyung Kim and Joo-Hyung Kim

Nanomaterials 2021, 11(11), 3053; https://doi.org/10.3390/nano11113053 - 13 Nov 2021

Cited by 3 | Viewed by 2228

Abstract

Due to the demand to upgrade from lithium-ion batteries (LIB), sodium-ion batteries (SIB) have been paid considerable attention for their high-energy, cost-effective, and sustainable battery system. Red phosphorus is one of the most promising anode candidates for SIBs, with a high theoretical specific [...] Read more.

Due to the demand to upgrade from lithium-ion batteries (LIB), sodium-ion batteries (SIB) have been paid considerable attention for their high-energy, cost-effective, and sustainable battery system. Red phosphorus is one of the most promising anode candidates for SIBs, with a high theoretical specific capacity of 2596 mAh g⁻¹ and in the discharge potential range of 0.01–0.8 V; however, it suffers from a low electrical conductivity, a substantial expansion of volume (~300%), and sluggish electron/ion kinetics. Herein, we have designed a well-defined electrode, which consists of red phosphorus, nanowire arrays encapsulated in the vertically aligned carbon nanotubes (P@C NWs), which were fabricated via a two-step, anodized-aluminum oxide template. The designed anode achieved a high specific capacity of 2250 mAh g⁻¹ (87% of the theoretical capacity), and a stepwise analysis of the reaction behavior between sodium and red phosphorus was demonstrated, both of which have not been navigated in previous studies. We believe that our rational design of the red phosphorus electrode elicited the specific reaction mechanism revealed by the charge–discharge profiles, rendered excellent electrical conductivity, and accommodated volume expansion through the effective nano-architecture, thereby suggesting an efficient structure for the phosphorus anode to advance in the future. Full article

(This article belongs to the Section Energy and Catalysis)

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29 pages, 4883 KiB

Open AccessEditor’s ChoiceReview

Modal Properties of Photonic Crystal Cavities and Applications to Lasers

by Marco Saldutti, Meng Xiong, Evangelos Dimopoulos, Yi Yu, Mariangela Gioannini and Jesper Mørk

Nanomaterials 2021, 11(11), 3030; https://doi.org/10.3390/nano11113030 - 12 Nov 2021

Cited by 29 | Viewed by 6179

Abstract

Photonic crystal cavities enable strong light–matter interactions, with numerous applications, such as ultra-small and energy-efficient semiconductor lasers, enhanced nonlinearities and single-photon sources. This paper reviews the properties of the modes of photonic crystal cavities, with a special focus on line-defect cavities. In particular, [...] Read more.

Photonic crystal cavities enable strong light–matter interactions, with numerous applications, such as ultra-small and energy-efficient semiconductor lasers, enhanced nonlinearities and single-photon sources. This paper reviews the properties of the modes of photonic crystal cavities, with a special focus on line-defect cavities. In particular, it is shown how the fundamental resonant mode in line-defect cavities gradually turns from Fabry–Perot-like to distributed-feedback-like with increasing cavity size. This peculiar behavior is directly traced back to the properties of the guided Bloch modes. Photonic crystal cavities based on Fano interference are also covered. This type of cavity is realized through coupling of a line-defect waveguide with an adjacent nanocavity, with applications to Fano lasers and optical switches. Finally, emerging cavities for extreme dielectric confinement are covered. These cavities promise extremely strong light–matter interactions by realizing deep sub-wavelength mode size while keeping a high quality factor. Full article

(This article belongs to the Special Issue Semiconductor and Nanophotonic Devices)

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10 pages, 32911 KiB

Open AccessEditor’s ChoiceArticle

Stable Field Emission from Vertically Oriented SiC Nanoarrays

by Jianfeng Xiao, Jiuzhou Zhao, Guanjiang Liu, Mattew Thomas Cole, Shenghan Zhou, Ke Chen, Xinchuan Liu, Zhenjun Li, Chi Li and Qing Dai

Nanomaterials 2021, 11(11), 3025; https://doi.org/10.3390/nano11113025 - 11 Nov 2021

Cited by 9 | Viewed by 2891

Abstract

Silicon carbide (SiC) nanostructure is a type of promising field emitter due to high breakdown field strength, high thermal conductivity, low electron affinity, and high electron mobility. However, the fabrication of the SiC nanotips array is difficult due to its chemical inertness. Here [...] Read more.

Silicon carbide (SiC) nanostructure is a type of promising field emitter due to high breakdown field strength, high thermal conductivity, low electron affinity, and high electron mobility. However, the fabrication of the SiC nanotips array is difficult due to its chemical inertness. Here we report a simple, industry-familiar reactive ion etching to fabricate well-aligned, vertically orientated SiC nanoarrays on 4H-SiC wafers. The as-synthesized nanoarrays had tapered base angles >60°, and were vertically oriented with a high packing density >10⁷ mm⁻² and high-aspect ratios of approximately 35. As a result of its high geometry uniformity—5% length variation and 10% diameter variation, the field emitter array showed typical turn-on fields of 4.3 V μm⁻¹ and a high field-enhancement factor of ~1260. The 8 h current emission stability displayed a mean current fluctuation of 1.9 ± 1%, revealing excellent current emission stability. The as-synthesized emitters demonstrate competitive emission performance that highlights their potential in a variety of vacuum electronics applications. This study provides a new route to realizing scalable field electron emitter production. Full article

(This article belongs to the Special Issue The Research Related to Nanomaterial Cold Cathode)

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24 pages, 6421 KiB

Open AccessEditor’s ChoiceArticle

Solar Light-Induced Methylene Blue Removal over TiO₂/AC Composites and Photocatalytic Regeneration

by Fernanda Dalto, Iwona Kuźniarska-Biernacka, Clara Pereira, Elsa Mesquita, Olívia Salomé G. P. Soares, M. Fernando R. Pereira, Maria João Rosa, Ana S. Mestre, Ana P. Carvalho and Cristina Freire

Nanomaterials 2021, 11(11), 3016; https://doi.org/10.3390/nano11113016 - 10 Nov 2021

Cited by 18 | Viewed by 4365

Abstract

TiO₂-containing photocatalysts, which combine TiO₂ with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO₂/AC composites were produced by the in situ immobilization of TiO₂ nanoparticles over [...] Read more.

TiO₂-containing photocatalysts, which combine TiO₂ with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO₂/AC composites were produced by the in situ immobilization of TiO₂ nanoparticles over activated carbon (AC) derived from spent coffee grains, using different TiO₂/AC proportions. The TiO₂/AC composites were tested as adsorbents (dark) and as photocatalysts in a combined adsorption+photocatalytic process (solar irradiation) for methylene blue (MB) removal from ultrapure water, and from a secondary effluent (SecEf) of an urban wastewater treatment plant. All the materials were characterized by XRD (X-ray powder diffraction), N₂ adsorption–desorption isotherms at −196 °C, SEM (scanning electron microscopy), UV-Vis diffuse reflectance, FTIR (Fourier-transform infrared spectroscopy), TPD (temperature programmed desorption), XPS (X-ray photoelectron spectroscopy) and TGA (thermogravimetric analysis). The TiAC60 (60% C) composite presented the lowest band gap (1.84 eV), while, for TiAC29 (29% C), the value was close to that of bare TiO₂ (3.18 vs. 3.17 eV). Regardless of the material, the solar irradiation improved the percentage of MB discolouration when compared to adsorption in dark conditions. In the case of simultaneous adsorption+photocatalytic assays performed in ultrapure water, TiAC29 presented the fastest MB removal. Nevertheless, both TiAC29 and TiAC60 led to excellent MB removal percentages (96.1–98.1%). UV-induced photoregeneration was a promising strategy to recover the adsorption capacity of the materials, especially for TiAC60 and AC (>95%). When the assays were performed in SecEf, all the materials promoted discolouration percentages close to those obtained in ultrapure water. The bulk water parameters revealed that TiAC60 allowed the removal of a higher amount of MB, associated with the overall improvement of the SecEf quality. Full article

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

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13 pages, 2282 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Optimization of Oxygen Evolution Reaction with Electroless Deposited Ni–P Catalytic Nanocoating

by Sergio Battiato, Mario Urso, Salvatore Cosentino, Anna Lucia Pellegrino, Salvo Mirabella and Antonio Terrasi

Nanomaterials 2021, 11(11), 3010; https://doi.org/10.3390/nano11113010 - 9 Nov 2021

Cited by 21 | Viewed by 3454

Abstract

The low efficiency of water electrolysis mostly arises from the thermodynamic uphill oxygen evolution reaction. The efficiency can be greatly improved by rationally designing low-cost and efficient oxygen evolution anode materials. Herein, we report the synthesis of Ni–P alloys adopting a facile electroless [...] Read more.

The low efficiency of water electrolysis mostly arises from the thermodynamic uphill oxygen evolution reaction. The efficiency can be greatly improved by rationally designing low-cost and efficient oxygen evolution anode materials. Herein, we report the synthesis of Ni–P alloys adopting a facile electroless plating method under mild conditions on nickel substrates. The relationship between the Ni–P properties and catalytic activity allowed us to define the best conditions for the electroless synthesis of highperformance Ni–P catalysts. Indeed, the electrochemical investigations indicated an increased catalytic response by reducing the thickness and Ni/P ratio in the alloy. Furthermore, the Ni–P catalysts with optimized size and composition deposited on Ni foam exposed more active sites for the oxygen evolution reaction, yielding a current density of 10 mA cm⁻² at an overpotential as low as 335 mV, exhibiting charge transfer resistances of only a few ohms and a remarkable turnover frequency (TOF) value of 0.62 s⁻¹ at 350 mV. The present study provides an advancement in the control of the electroless synthetic approach for the design and large-scale application of high-performance metal phosphide catalysts for electrochemical water splitting. Full article

(This article belongs to the Special Issue Nanocatalysts for Electro-Oxidation)

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20 pages, 4601 KiB

Open AccessEditor’s ChoiceArticle

Spatial Period of Laser-Induced Surface Nanoripples on PET Determines Escherichia coli Repellence

by Anja M. Richter, Gerda Buchberger, David Stifter, Jiri Duchoslav, Andreas Hertwig, Jörn Bonse, Johannes Heitz and Karin Schwibbert

Nanomaterials 2021, 11(11), 3000; https://doi.org/10.3390/nano11113000 - 8 Nov 2021

Cited by 28 | Viewed by 3419

Abstract

Bacterial adhesion and biofilm formation on surfaces are associated with persistent microbial contamination, biofouling, and the emergence of resistance, thus, calling for new strategies to impede bacterial surface colonization. Using ns-UV laser treatment (wavelength 248 nm and a pulse duration of 20 ns), [...] Read more.

Bacterial adhesion and biofilm formation on surfaces are associated with persistent microbial contamination, biofouling, and the emergence of resistance, thus, calling for new strategies to impede bacterial surface colonization. Using ns-UV laser treatment (wavelength 248 nm and a pulse duration of 20 ns), laser-induced periodic surface structures (LIPSS) featuring different sub-micrometric periods ranging from ~210 to ~610 nm were processed on commercial poly(ethylene terephthalate) (PET) foils. Bacterial adhesion tests revealed that these nanorippled surfaces exhibit a repellence for E. coli that decisively depends on the spatial periods of the LIPSS with the strongest reduction (~91%) in cell adhesion observed for LIPSS periods of 214 nm. Although chemical and structural analyses indicated a moderate laser-induced surface oxidation, a significant influence on the bacterial adhesion was ruled out. Scanning electron microscopy and additional biofilm studies using a pili-deficient E. coli TG1 strain revealed the role of extracellular appendages in the bacterial repellence observed here. Full article

(This article belongs to the Special Issue Nanopatterning of Bionic Materials)

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14 pages, 2876 KiB

Open AccessEditor’s ChoiceArticle

Accumulation and Effect of Silver Nanoparticles Functionalized with Spirulina platensis on Rats

by Ludmila Rudi, Inga Zinicovscaia, Liliana Cepoi, Tatiana Chiriac, Alexandra Peshkova, Anastasia Cepoi and Dmitrii Grozdov

Nanomaterials 2021, 11(11), 2992; https://doi.org/10.3390/nano11112992 - 7 Nov 2021

Cited by 14 | Viewed by 3088

Abstract

The effect of unmodified and functionalized Spirulina platensis biomass silver nanoparticles on rats during prolonged oral administration was assessed. Silver nanoparticles were characterized by using transmission electron microscopy, while their uptake by the biomass was confirmed using scanning electron microscopy and energy dispersive [...] Read more.

The effect of unmodified and functionalized Spirulina platensis biomass silver nanoparticles on rats during prolonged oral administration was assessed. Silver nanoparticles were characterized by using transmission electron microscopy, while their uptake by the biomass was confirmed using scanning electron microscopy and energy dispersive analysis. The content of silver in the different organs of rats after a period of administration (28 days) or after an additional clearance period (28 days) was ascertained by using neutron activation analysis. In animals administrated with the unmodified nanoparticles, the highest content of silver was determined in the brain and kidneys, while in animals administrated with AgNP-Spirulina, silver was mainly accumulated in the brain and testicles. After the clearance period, silver was excreted rapidly from the spleen and kidneys; however, the excretion from the brain was very low, regardless of the type of nanoparticles. Hematological and biochemical tests were performed in order to reveal the effect of nanoparticles on rats. The difference in the content of eosinophils in the experimental and control groups was statistically significant. The hematological indices of the rats did not change significantly under the action of the silver nanoparticles except for the content of reticulocytes and eosinophils, which increased significantly. Changes in the biochemical parameters did not exceed the limits of normal values. Silver nanoparticles with the sizes of 8–20 nm can penetrate the blood–brain barrier, and their persistence after a period of clearance indicated the irreversibility of this process. Full article

(This article belongs to the Special Issue Nanoparticles Drug Delivery)

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16 pages, 4099 KiB

Open AccessEditor’s ChoiceArticle

Ultra-Low-Loss Mid-Infrared Plasmonic Waveguides Based on Multilayer Graphene Metamaterials

by Chia-Chien Huang, Ruei-Jan Chang and Ching-Wen Cheng

Nanomaterials 2021, 11(11), 2981; https://doi.org/10.3390/nano11112981 - 6 Nov 2021

Cited by 9 | Viewed by 2625

Abstract

Manipulating optical signals in the mid-infrared (mid-IR) range is a highly desired task for applications in chemical sensing, thermal imaging, and subwavelength optical waveguiding. To guide highly confined mid-IR light in photonic chips, graphene-based plasmonics capable of breaking the optical diffraction limit offer [...] Read more.

Manipulating optical signals in the mid-infrared (mid-IR) range is a highly desired task for applications in chemical sensing, thermal imaging, and subwavelength optical waveguiding. To guide highly confined mid-IR light in photonic chips, graphene-based plasmonics capable of breaking the optical diffraction limit offer a promising solution. However, the propagation lengths of these materials are, to date, limited to approximately 10 µm at the working frequency f = 20 THz. In this study, we proposed a waveguide structure consisting of multilayer graphene metamaterials (MLGMTs). The MLGMTs support the fundamental volume plasmon polariton mode by coupling plasmon polaritons at individual graphene sheets over a silicon nano-rib structure. Benefiting from the high conductivity of the MLGMTs, the guided mode shows ultralow loss compared with that of conventional graphene-based plasmonic waveguides at comparable mode sizes. The proposed design demonstrated propagation lengths of approximately 20 µm (four times the current limitations) at an extremely tight mode area of 10⁻⁶A₀, where A₀ is the diffraction-limited mode area. The dependence of modal characteristics on geometry and material parameters are investigated in detail to identify optimal device performance. Moreover, fabrication imperfections are also addressed to evaluate the robustness of the proposed structure. Moreover, the crosstalk between two adjacent present waveguides is also investigated to demonstrate the high mode confinement to realize high-density on-chip devices. The present design offers a potential waveguiding approach for building tunable and large-area photonic integrated circuits. Full article

(This article belongs to the Special Issue Plasmonic Nanostructures: Properties, Characterization, and Applications)

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15 pages, 1670 KiB

Open AccessEditor’s ChoiceReview

Carbon Nanomaterials Modified Biomimetic Dental Implants for Diabetic Patients

by Renjini Vijay, Jayanti Mendhi, Karthika Prasad, Yin Xiao, Jennifer MacLeod, Kostya (Ken) Ostrikov and Yinghong Zhou

Nanomaterials 2021, 11(11), 2977; https://doi.org/10.3390/nano11112977 - 5 Nov 2021

Cited by 22 | Viewed by 4708

Abstract

Dental implants are used broadly in dental clinics as the most natural-looking restoration option for replacing missing or highly diseased teeth. However, dental implant failure is a crucial issue for diabetic patients in need of dentition restoration, particularly when a lack of osseointegration [...] Read more.

Dental implants are used broadly in dental clinics as the most natural-looking restoration option for replacing missing or highly diseased teeth. However, dental implant failure is a crucial issue for diabetic patients in need of dentition restoration, particularly when a lack of osseointegration and immunoregulatory incompetency occur during the healing phase, resulting in infection and fibrous encapsulation. Bio-inspired or biomimetic materials, which can mimic the characteristics of natural elements, are being investigated for use in the implant industry. This review discusses different biomimetic dental implants in terms of structural changes that enable antibacterial properties, drug delivery, immunomodulation, and osseointegration. We subsequently summarize the modification of dental implants for diabetes patients utilizing carbon nanomaterials, which have been recently found to improve the characteristics of biomimetic dental implants, including through antibacterial and anti-inflammatory capabilities, and by offering drug delivery properties that are essential for the success of dental implants. Full article

(This article belongs to the Special Issue Bionanotechnology and Nanobiotechnology: Biomimetics or Engineering Nature?)

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17 pages, 2698 KiB

Open AccessEditor’s ChoiceArticle

Structure–Activity Relationship of Graphene-Based Materials: Impact of the Surface Chemistry, Surface Specific Area and Lateral Size on Their In Vitro Toxicity

by Salma Achawi, Bruno Feneon, Jérémie Pourchez and Valérie Forest

Nanomaterials 2021, 11(11), 2963; https://doi.org/10.3390/nano11112963 - 4 Nov 2021

Cited by 24 | Viewed by 2432

Abstract

Predictive toxicity and structure–activity relationships (SARs) are raising interest since the number of nanomaterials has become unmanageable to assess their toxicity with a classical case-by-case approach. Graphene-based materials (GBMs) are among the most promising nanomaterials of this decade and their application might lead [...] Read more.

Predictive toxicity and structure–activity relationships (SARs) are raising interest since the number of nanomaterials has become unmanageable to assess their toxicity with a classical case-by-case approach. Graphene-based materials (GBMs) are among the most promising nanomaterials of this decade and their application might lead to several innovations. However, their toxicity impact needs to be thoroughly assessed. In this regard, we conducted a study on 22 GBMs to investigate their potential SARs by performing a complete physicochemical characterization and in vitro toxicity assessment (on RAW264.7 cells). We used GBMs of variable lateral size (0.5–38 µm), specific surface area (SSA, 30–880 m²/g), and surface oxidation (2–17%). We observed that reduced graphene oxides (RGOs) were more reactive than graphene nanoplatelets (GNPs), potentially highlighting the role of GBM’s surface chemistry and surface defects density in their biological impact. We also observed that for GNPs, a smaller lateral size caused higher cytotoxicity. Lastly, GBMs showing a SSA higher than 200 m²/g were found to induce a higher ROS production. Mechanistic explanations are proposed in the discussion. In conclusion, pairing a full physicochemical characterization with a standardized toxicity assessment of a large set of samples allowed us to clarify SARs and provide an additional step toward safe-by-design GBMs. Full article

(This article belongs to the Special Issue Safety Assessment of Graphene-Based Materials: Human Health and Environment)

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8 pages, 792 KiB

Open AccessEditor’s ChoiceArticle

Metamaterial-Engineered Silicon Beam Splitter Fabricated with Deep UV Immersion Lithography

by Vladyslav Vakarin, Daniele Melati, Thi Thuy Duong Dinh, Xavier Le Roux, Warren Kut King Kan, Cécilia Dupré, Bertrand Szelag, Stéphane Monfray, Frédéric Boeuf, Pavel Cheben, Eric Cassan, Delphine Marris-Morini, Laurent Vivien and Carlos Alberto Alonso-Ramos

Nanomaterials 2021, 11(11), 2949; https://doi.org/10.3390/nano11112949 - 3 Nov 2021

Cited by 18 | Viewed by 2848

Abstract

Subwavelength grating (SWG) metamaterials have garnered a great interest for their singular capability to shape the material properties and the propagation of light, allowing the realization of devices with unprecedented performance. However, practical SWG implementations are limited by fabrication constraints, such as minimum [...] Read more.

Subwavelength grating (SWG) metamaterials have garnered a great interest for their singular capability to shape the material properties and the propagation of light, allowing the realization of devices with unprecedented performance. However, practical SWG implementations are limited by fabrication constraints, such as minimum feature size, that restrict the available design space or compromise compatibility with high-volume fabrication technologies. Indeed, most successful SWG realizations so far relied on electron-beam lithographic techniques, compromising the scalability of the approach. Here, we report the experimental demonstration of an SWG metamaterial engineered beam splitter fabricated with deep-ultraviolet immersion lithography in a 300-mm silicon-on-insulator technology. The metamaterial beam splitter exhibits high performance over a measured bandwidth exceeding 186 nm centered at 1550 nm. These results open a new route for the development of scalable silicon photonic circuits exploiting flexible metamaterial engineering. Full article

(This article belongs to the Special Issue Silicon Photonics: Synthesis and Applications)

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20 pages, 3530 KiB

Open AccessEditor’s ChoiceArticle

Coating of Magnetite Nanoparticles with Fucoidan to Enhance Magnetic Hyperthermia Efficiency

by Joana Gonçalves, Cláudia Nunes, Liliana Ferreira, Maria Margarida Cruz, Helena Oliveira, Verónica Bastos, Álvaro Mayoral, Qing Zhang and Paula Ferreira

Nanomaterials 2021, 11(11), 2939; https://doi.org/10.3390/nano11112939 - 2 Nov 2021

Cited by 17 | Viewed by 3588

Abstract

Magnetic nanoparticles (NP), such as magnetite, have been the subject of research for application in the biomedical field, especially in Magnetic Hyperthermia Therapy (MHT), a promising technique for cancer therapy. NP are often coated with different compounds such as natural or synthetic polymers [...] Read more.

Magnetic nanoparticles (NP), such as magnetite, have been the subject of research for application in the biomedical field, especially in Magnetic Hyperthermia Therapy (MHT), a promising technique for cancer therapy. NP are often coated with different compounds such as natural or synthetic polymers to protect them from oxidation and enhance their colloidal electrostatic stability while maintaining their thermal efficiency. In this work, the synthesis and characterization of magnetite nanoparticles coated with fucoidan, a biopolymer with recognized biocompatibility and antitumoral activity, is reported. The potential application of NP in MHT was evaluated through the assessment of Specific Loss Power (SLP) under an electromagnetic field amplitude of 14.7 kA m⁻¹ and at 276 kHz. For fucoidan-coated NP, it was obtained SLP values of 100 and 156 W/g, corresponding to an Intrinsic Loss Power (ILP) of 1.7 and 2.6 nHm²kg⁻¹, respectively. These values are, in general, higher than the ones reported in the literature for non-coated magnetite NP or coated with other polymers. Furthermore, in vitro assays showed that fucoidan and fucoidan-coated NP are biocompatible. The particle size (between ca. 6 to 12 nm), heating efficiency, and biocompatibility of fucoidan-coated magnetite NP meet the required criteria for MHT application. Full article

(This article belongs to the Special Issue Multifunctional Magnetic Nanocomposites: Innovative Processing and Applications)

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10 pages, 33527 KiB

Open AccessEditor’s ChoiceArticle

Silicon-Based All-Dielectric Metasurface on an Iron Garnet Film for Efficient Magneto-Optical Light Modulation in Near IR Range

by Denis M. Krichevsky, Shuang Xia, Mikhail P. Mandrik, Daria O. Ignatyeva, Lei Bi and Vladimir I. Belotelov

Nanomaterials 2021, 11(11), 2926; https://doi.org/10.3390/nano11112926 - 1 Nov 2021

Cited by 12 | Viewed by 2960

Abstract

All-dielectric nanostructures provide a unique low-loss platform for efficiently increasing light-matter interaction via excitation of the localized or propagating optical modes. Here, we report on the transverse magneto-optical Kerr effect enhancement in an all-dielectric metasurface based on a two-dimensional array of Si nanodisks [...] Read more.

All-dielectric nanostructures provide a unique low-loss platform for efficiently increasing light-matter interaction via excitation of the localized or propagating optical modes. Here, we report on the transverse magneto-optical Kerr effect enhancement in an all-dielectric metasurface based on a two-dimensional array of Si nanodisks on a cerium substituted dysprosium iron garnet thin film. We observed up to 15% light intensity modulation under TM modes excitation. The observed magneto-optical effect is nearly independent of the rotation of the light incidence plane with respect to the metasurface. Being compatible with conventional semiconductor technology, our structure holds promise for device applications, such as light modulators, magnetic and chemical sensors. Full article

(This article belongs to the Special Issue Nanophotonic and Optical Nanomaterials)

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25 pages, 17339 KiB

Open AccessEditor’s ChoiceArticle

Computational Modeling of Hybrid Carbon Fiber/Epoxy Composites Reinforced with Functionalized and Non-Functionalized Graphene Nanoplatelets

by Hashim Al Mahmud, Matthew S. Radue, William A. Pisani and Gregory M. Odegard

Nanomaterials 2021, 11(11), 2919; https://doi.org/10.3390/nano11112919 - 31 Oct 2021

Cited by 11 | Viewed by 3945

Abstract

The mechanical properties of aerospace carbon fiber/graphene nanoplatelet/epoxy hybrid composites reinforced with pristine graphene nanoplatelets (GNP), highly concentrated graphene oxide (GO), and Functionalized Graphene Oxide (FGO) are investigated in this study. By utilizing molecular dynamics data from the literature, the bulk-level mechanical properties [...] Read more.

The mechanical properties of aerospace carbon fiber/graphene nanoplatelet/epoxy hybrid composites reinforced with pristine graphene nanoplatelets (GNP), highly concentrated graphene oxide (GO), and Functionalized Graphene Oxide (FGO) are investigated in this study. By utilizing molecular dynamics data from the literature, the bulk-level mechanical properties of hybrid composites are predicted using micromechanics techniques for different graphene nanoplatelet types, nanoplatelet volume fractions, nanoplatelet aspect ratios, carbon fiber volume fractions, and laminate lay-ups (unidirectional, cross-ply, and angle-ply). For the unidirectional hybrid composites, the results indicate that the shear and transverse properties are significantly affected by the nanoplatelet type, loading and aspect ratio. For the cross-ply and angle ply hybrid laminates, the effect of the nanoplate’s parameters on the mechanical properties is minimal when using volume fractions and aspect ratios that are typically used experimentally. The results of this study can be used in the design of hybrid composites to tailor specific laminate properties by adjusting nanoplatelet parameters. Full article

(This article belongs to the Special Issue Nanocomposite Materials—Spotlight on Early Career Investigators)

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15 pages, 4357 KiB

Open AccessEditor’s ChoiceArticle

Simulation of Solar Cells with Integration of Optical Nanoantennas

by Inês Margarida Pinheiro Caetano, João Paulo N. Torres and Ricardo A. Marques Lameirinhas

Nanomaterials 2021, 11(11), 2911; https://doi.org/10.3390/nano11112911 - 30 Oct 2021

Cited by 4 | Viewed by 2239

Abstract

The evolution of nanotechnology has provided a better understanding of light-matter interaction at a subwavelength scale and has led to the development of new devices that can possibly play an important role in future applications. Nanoantennas are an example of such devices, having [...] Read more.

The evolution of nanotechnology has provided a better understanding of light-matter interaction at a subwavelength scale and has led to the development of new devices that can possibly play an important role in future applications. Nanoantennas are an example of such devices, having gained interest in recent years for their application in the field of photovoltaic technology at visible and infrared wavelengths, due to their ability to capture and confine energy of free-propagating waves. This property results from a unique phenomenon called extraordinary optical transmission (EOT) where, due to resonant behavior, light passing through subwavelength apertures in a metal film can be transmitted in greater orders of magnitude than that predicted by classical theories. During this study, 2D and 3D models featuring a metallic nanoantenna array with subwavelength holes coupled to a photovoltaic cell are simulated using a Finite Element Tool. These models present with slight variations between them, such as the position of the nanoantenna within the structure, the holes’ geometry and the type of cell, in order to verify how its optical response is affected. The results demonstrate that the coupling of nanoantennas to solar cells can be advantageous and improve the capture and absorption of radiation. It is concluded that aperture nanoantennas may concentrate radiation, meaning that is possible to tune the electric field peak and adjust absorption on the main layers. This may be important because it might be possible to adjust solar cell performance to the global regions’ solar spectrum by only adjusting the nanoantenna parameters. Full article

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15 pages, 3416 KiB

Open AccessEditor’s ChoiceArticle

Designing a Graphene Coating-Based Supercapacitor with Lithium Ion Electrolyte: An Experimental and Computational Study via Multiscale Modeling

by Joseph Paul Baboo, Shumaila Babar, Dhaval Kale, Constantina Lekakou and Giuliano M. Laudone

Nanomaterials 2021, 11(11), 2899; https://doi.org/10.3390/nano11112899 - 29 Oct 2021

Cited by 16 | Viewed by 2718

Abstract

Graphene electrodes are investigated for electrochemical double layer capacitors (EDLCs) with lithium ion electrolyte, the focus being the effect of the pore size distribution (PSD) of electrode with respect to the solvated and desolvated electrolyte ions. Two graphene electrode coatings are examined: a [...] Read more.

Graphene electrodes are investigated for electrochemical double layer capacitors (EDLCs) with lithium ion electrolyte, the focus being the effect of the pore size distribution (PSD) of electrode with respect to the solvated and desolvated electrolyte ions. Two graphene electrode coatings are examined: a low specific surface area (SSA) xGNP-750 coating and a high SSA coating based on a-MWGO (activated microwave expanded graphene oxide). The study comprises an experimental and a computer modeling part. The experimental part includes fabrication, material characterization and electrochemical testing of an EDLC with xGNP-750 coating electrodes and electrolyte 1M LiPF6 in EC:DMC. The computational part includes simulations of the galvanostatic charge-discharge of each EDLC type, based on a continuum ion transport model taking into account the PSD of electrodes, as well as molecular modeling to determine the parameters of the solvated and desolvated electrolyte ions and their adsorption energies with each type of electrode pore surface material. Predictions, in agreement with the experimental data, yield a specific electrode capacitance of 110 F g⁻¹ for xGNP-750 coating electrodes in electrolyte 1M LiPF₆ in EC:DMC, which is three times higher than that of the high SSA a-MWGO coating electrodes in the same lithium ion electrolyte. Full article

(This article belongs to the Special Issue Nanomaterials for Green Energy Applications)

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20 pages, 2724 KiB

Open AccessEditor’s ChoiceArticle

Influence of Coating and Size of Magnetic Nanoparticles on Cellular Uptake for In Vitro MRI

by Belén Cortés-Llanos, Sandra M. Ocampo, Leonor de la Cueva, Gabriel F. Calvo, Juan Belmonte-Beitia, Lucas Pérez, Gorka Salas and Ángel Ayuso-Sacido

Nanomaterials 2021, 11(11), 2888; https://doi.org/10.3390/nano11112888 - 28 Oct 2021

Cited by 21 | Viewed by 3668

Abstract

Iron oxide nanoparticles (IONPs) are suitable materials for contrast enhancement in magnetic resonance imaging (MRI). Their potential clinical applications range from diagnosis to therapy and follow-up treatments. However, a deeper understanding of the interaction between IONPs, culture media and cells is necessary for [...] Read more.

Iron oxide nanoparticles (IONPs) are suitable materials for contrast enhancement in magnetic resonance imaging (MRI). Their potential clinical applications range from diagnosis to therapy and follow-up treatments. However, a deeper understanding of the interaction between IONPs, culture media and cells is necessary for expanding the application of this technology to different types of cancer therapies. To achieve new insights of these interactions, a set of IONPs were prepared with the same inorganic core and five distinct coatings, to study their aggregation and interactions in different physiological media, as well as their cell labelling efficiency. Then, a second set of IONPs, with six different core sizes and the same coating, were used to study how the core size affects cell labelling and MRI in vitro. Here, IONPs suspended in biological media experience a partial removal of the coating and adhesion of molecules. The FBS concentration alters the labelling of all types of IONPs and hydrodynamic sizes ≥ 300 nm provide the greatest labelling using the centrifugation-mediated internalization (CMI). The best contrast for MRI results requires a core size range between 12–14 nm coated with dimercaptosuccinic acid (DMSA) producing R₂^* values of 393.7 s⁻¹ and 428.3 s⁻¹, respectively. These findings will help to bring IONPs as negative contrast agents into clinical settings. Full article

(This article belongs to the Special Issue Multifunctional Magnetic Nanowires and Nanotubes)

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16 pages, 1380 KiB

Open AccessEditor’s ChoiceReview

Direct and Indirect Genotoxicity of Graphene Family Nanomaterials on DNA—A Review

by Kangying Wu, Qixing Zhou and Shaohu Ouyang

Nanomaterials 2021, 11(11), 2889; https://doi.org/10.3390/nano11112889 - 28 Oct 2021

Cited by 36 | Viewed by 4204

Abstract

Graphene family nanomaterials (GFNs), including graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs), have manifold potential applications, leading to the possibility of their release into environments and the exposure to humans and other organisms. However, the genotoxicity of [...] Read more.

Graphene family nanomaterials (GFNs), including graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs), have manifold potential applications, leading to the possibility of their release into environments and the exposure to humans and other organisms. However, the genotoxicity of GFNs on DNA remains largely unknown. In this review, we highlight the interactions between DNA and GFNs and summarize the mechanisms of genotoxicity induced by GFNs. Generally, the genotoxicity can be sub-classified into direct genotoxicity and indirect genotoxicity. The direct genotoxicity (e.g., direct physical nucleus and DNA damage) and indirect genotoxicity mechanisms (e.g., physical destruction, oxidative stress, epigenetic toxicity, and DNA replication) of GFNs were summarized in the manuscript, respectively. Moreover, the influences factors, such as physicochemical properties, exposure dose, and time, on the genotoxicity of GFNs are also briefly discussed. Given the important role of genotoxicity in GFNs exposure risk assessment, future research should be conducted on the following: (1) developing reliable testing methods; (2) elucidating the response mechanisms associated with genotoxicity in depth; and (3) enriching the evaluation database regarding the type of GFNs, applied dosages, and exposure times. Full article

(This article belongs to the Special Issue The Genetic Changes Induced by Engineered Manufactured Nanomaterials (EMNs))

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23 pages, 4418 KiB

Open AccessEditor’s ChoiceArticle

Stable Aqueous Colloidal Solutions of Nd³⁺: LaF₃ Nanoparticles, Promising for Luminescent Bioimaging in the Near-Infrared Spectral Range

by Alexandr Popov, Elena Orlovskaya, Artem Shaidulin, Ekaterina Vagapova, Elena Timofeeva, Leonid Dolgov, Lyudmila Iskhakova, Oleg Uvarov, Grigoriy Novikov, Mihkel Rähn, Aile Tamm, Alexander Vanetsev, Stanislav Fedorenko, Svetlana Eliseeva, Stephane Petoud and Yurii Orlovskii

Nanomaterials 2021, 11(11), 2847; https://doi.org/10.3390/nano11112847 - 26 Oct 2021

Cited by 6 | Viewed by 2584

Abstract

Two series of stable aqueous colloidal solutions of Nd³⁺: LaF₃ single-phase well-crystallized nanoparticles (NPs), possessing a fluorcerite structure with different activator concentrations in each series, were synthesized. A hydrothermal method involving microwave-assisted heating (HTMW) in two Berghof speedwave devices equipped [...] Read more.

Two series of stable aqueous colloidal solutions of Nd³⁺: LaF₃ single-phase well-crystallized nanoparticles (NPs), possessing a fluorcerite structure with different activator concentrations in each series, were synthesized. A hydrothermal method involving microwave-assisted heating (HTMW) in two Berghof speedwave devices equipped with one magnetron (type I) or two magnetrons (type II) was used. The average sizes of NPs are 15.4 ± 6 nm (type I) and 21 ± 7 nm (type II). Both types of NPs have a size distribution that is well described by a double Gaussian function. The fluorescence kinetics of the ⁴F_3/2 level of the Nd³⁺ ion for NPs of both types, in contrast to a similar bulk crystal, demonstrates a luminescence quenching associated not only with Nd–Nd self-quenching, but also with an additional Nd–OH quenching. A method has been developed for determining the spontaneous radiative lifetime of the excited state of a dopant ion, with the significant contribution of the luminescence quenching caused by the presence of the impurity OH– acceptors located in the bulk of NPs. The relative quantum yield of fluorescence and the fluorescence brightness of an aqueous colloidal solution of type II NPs with an optimal concentration of Nd³⁺ are only 2.5 times lower than those of analogous Nd³⁺: LaF₃ single crystals. Full article

(This article belongs to the Special Issue Up- and Down-Conversion Nanoparticles for Light Sources and Theranostics)

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25 pages, 61242 KiB

Open AccessEditor’s ChoiceReview

Graphene Transfer: A Physical Perspective

by Xavier Langston and Keith E. Whitener, Jr.

Nanomaterials 2021, 11(11), 2837; https://doi.org/10.3390/nano11112837 - 25 Oct 2021

Cited by 13 | Viewed by 7140

Abstract

Graphene, synthesized either epitaxially on silicon carbide or via chemical vapor deposition (CVD) on a transition metal, is gathering an increasing amount of interest from industrial and commercial ventures due to its remarkable electronic, mechanical, and thermal properties, as well as the ease [...] Read more.

Graphene, synthesized either epitaxially on silicon carbide or via chemical vapor deposition (CVD) on a transition metal, is gathering an increasing amount of interest from industrial and commercial ventures due to its remarkable electronic, mechanical, and thermal properties, as well as the ease with which it can be incorporated into devices. To exploit these superlative properties, it is generally necessary to transfer graphene from its conductive growth substrate to a more appropriate target substrate. In this review, we analyze the literature describing graphene transfer methods developed over the last decade. We present a simple physical model of the adhesion of graphene to its substrate, and we use this model to organize the various graphene transfer techniques by how they tackle the problem of modulating the adhesion energy between graphene and its substrate. We consider the challenges inherent in both delamination of graphene from its original substrate as well as relamination of graphene onto its target substrate, and we show how our simple model can rationalize various transfer strategies to mitigate these challenges and overcome the introduction of impurities and defects into the graphene. Our analysis of graphene transfer strategies concludes with a suggestion of possible future directions for the field. Full article

(This article belongs to the Special Issue Two Dimensional Nanomaterials: Energy Conversion and Storage)

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10 pages, 2730 KiB

Open AccessEditor’s ChoiceArticle

Thermal Radiative Copper Oxide Layer for Enhancing Heat Dissipation of Metal Surface

by Junghyun Park, Donghyun Kim, Hyunsik Kim, Junghoon Lee and Wonsub Chung

Nanomaterials 2021, 11(11), 2819; https://doi.org/10.3390/nano11112819 - 24 Oct 2021

Cited by 13 | Viewed by 3755

Abstract

The heat dissipation of a metal heat sink for passive cooling can be enhanced by surface modifications to increase its thermal emissivity, which is reflected by a darker surface appearance. In this study, copper electrodeposition followed by heat treatment was applied to a [...] Read more.

The heat dissipation of a metal heat sink for passive cooling can be enhanced by surface modifications to increase its thermal emissivity, which is reflected by a darker surface appearance. In this study, copper electrodeposition followed by heat treatment was applied to a copper substrate. The heat treatment formed a nanoporous oxide layer containing CuO and Cu₂O, which has a dark blackish color and therefore increased the thermal emissivity of the surface. The heat dissipation performance was evaluated using the sample as a heat sink for an LED module. The surface-treated copper heat sink with a high thermal emissivity oxide layer enhanced the heat dissipation of the LED module and allowed it to be operated at a lower temperature. With an increase in the heat treatment, the thermal emissivity increases to 0.865, but the thermal diffusivity is lower than the copper substrate by ~12%. These results indicate that the oxide layer is a thermal barrier for heat transfer, thus optimization between the oxide thickness and thermal emissivity is required by evaluating heat dissipation performance in operating conditions. In this study, an oxide layer with an emissivity of 0.857 and ~5% lower thermal diffusivity than the copper substrate showed the lowest LED operating temperature. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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