Nanomaterials

17 pages, 4665 KiB

Open AccessArticle

Early-Stage Growth Mechanism and Synthesis Conditions-Dependent Morphology of Nanocrystalline Bi Films Electrodeposited from Perchlorate Electrolyte

by Daria Tishkevich, Sergey Grabchikov, Tatiana Zubar, Denis Vasin, Sergei Trukhanov, Alla Vorobjova, Dmitry Yakimchuk, Artem Kozlovskiy, Maxim Zdorovets, Sholpan Giniyatova, Dmitriy Shimanovich, Dmitry Lyakhov, Dominik Michels, Mengge Dong, Svetlana Gudkova and Alex Trukhanov

Nanomaterials 2020, 10(6), 1245; https://doi.org/10.3390/nano10061245 - 27 Jun 2020

Cited by 52 | Viewed by 4502

Abstract

Bi nanocrystalline films were formed from perchlorate electrolyte (PE) on Cu substrate via electrochemical deposition with different duration and current densities. The microstructural, morphological properties, and elemental composition were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray microanalysis [...] Read more.

Bi nanocrystalline films were formed from perchlorate electrolyte (PE) on Cu substrate via electrochemical deposition with different duration and current densities. The microstructural, morphological properties, and elemental composition were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray microanalysis (EDX). The optimal range of current densities for Bi electrodeposition in PE using polarization measurements was demonstrated. For the first time, it was shown and explained why, with a deposition duration of 1 s, co-deposition of Pb and Bi occurs. The correlation between synthesis conditions and chemical composition and microstructure for Bi films was discussed. The analysis of the microstructure evolution revealed the changing mechanism of the films’ growth from pillar-like (for Pb-rich phase) to layered granular form (for Bi) with deposition duration rising. This abnormal behavior is explained by the appearance of a strong Bi growth texture and coalescence effects. The investigations of porosity showed that Bi films have a closely-packed microstructure. The main stages and the growth mechanism of Bi films in the galvanostatic regime in PE with a deposition duration of 1–30 s are proposed. Full article

(This article belongs to the Special Issue Bimetallic Nanoparticles)

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8 pages, 1226 KiB

Open AccessArticle

Stress Buildup Upon Crystallization of GeTe Thin Films: Curvature Measurements and Modelling

by Rajkiran Tholapi, Manon Gallard, Nelly Burle, Christophe Guichet, Stephanie Escoubas, Magali Putero, Cristian Mocuta, Marie-Ingrid Richard, Rebecca Chahine, Chiara Sabbione, Mathieu Bernard, Leila Fellouh, Pierre Noé and Olivier Thomas

Nanomaterials 2020, 10(6), 1247; https://doi.org/10.3390/nano10061247 - 26 Jun 2020

Cited by 2 | Viewed by 2920

Abstract

Phase change materials are attractive materials for non-volatile memories because of their ability to switch reversibly between an amorphous and a crystal phase. The volume change upon crystallization induces mechanical stress that needs to be understood and controlled. In this work, we monitor [...] Read more.

Phase change materials are attractive materials for non-volatile memories because of their ability to switch reversibly between an amorphous and a crystal phase. The volume change upon crystallization induces mechanical stress that needs to be understood and controlled. In this work, we monitor stress evolution during crystallization in thin GeTe films capped with SiO_x, using optical curvature measurements. A 150 MPa tensile stress buildup is measured when the 100 nm thick film crystallizes. Stress evolution is a result of viscosity increase with time and a tentative model is proposed that renders qualitatively the observed features. Full article

(This article belongs to the Special Issue Characterization of Nanomaterials)

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17 pages, 3367 KiB

Open AccessFeature PaperArticle

Fast and Accurate Pneumocystis Pneumonia Diagnosis in Human Samples Using a Label-Free Plasmonic Biosensor

by Olalla Calvo-Lozano, Anna Aviñó, Vicente Friaza, Alfonso Medina-Escuela, César S. Huertas, Enrique J. Calderón, Ramón Eritja and Laura M. Lechuga

Nanomaterials 2020, 10(6), 1246; https://doi.org/10.3390/nano10061246 - 26 Jun 2020

Cited by 14 | Viewed by 4497

Abstract

Pneumocystis jirovecii is a fungus responsible for human Pneumocystis pneumonia, one of the most severe infections encountered in immunodepressed individuals. The diagnosis of Pneumocystis pneumonia continues to be challenging due to the absence of specific symptoms in infected patients. Moreover, the standard diagnostic [...] Read more.

Pneumocystis jirovecii is a fungus responsible for human Pneumocystis pneumonia, one of the most severe infections encountered in immunodepressed individuals. The diagnosis of Pneumocystis pneumonia continues to be challenging due to the absence of specific symptoms in infected patients. Moreover, the standard diagnostic method employed for its diagnosis involves mainly PCR-based techniques, which besides being highly specific and sensitive, require specialized personnel and equipment and are time-consuming. Our aim is to demonstrate an optical biosensor methodology based on surface plasmon resonance to perform such diagnostics in an efficient and decentralized scheme. The biosensor methodology employs poly-purine reverse-Hoogsteen hairpin probes for the detection of the mitochondrial large subunit ribosomal RNA (mtLSU rRNA) gene, related to P. jirovecii detection. The biosensor device performs a real-time and label-free identification of the mtLSU rRNA gene with excellent selectivity and reproducibility, achieving limits of detection of around 2.11 nM. A preliminary evaluation of clinical samples showed rapid, label-free and specific identification of P. jirovecii in human lung fluids such as bronchoalveolar lavages or nasopharyngeal aspirates. These results offer a door for the future deployment of a sensitive diagnostic tool for fast, direct and selective detection of Pneumocystis pneumonia disease. Full article

(This article belongs to the Special Issue The Application of DNA Nanotechnology)

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27 pages, 3270 KiB

Open AccessReview

Multi-Scale Surface Treatments of Titanium Implants for Rapid Osseointegration: A Review

by Qingge Wang, Peng Zhou, Shifeng Liu, Shokouh Attarilar, Robin Lok-Wang Ma, Yinsheng Zhong and Liqiang Wang

Nanomaterials 2020, 10(6), 1244; https://doi.org/10.3390/nano10061244 - 26 Jun 2020

Cited by 160 | Viewed by 9120

Abstract

The propose of this review was to summarize the advances in multi-scale surface technology of titanium implants to accelerate the osseointegration process. The several multi-scaled methods used for improving wettability, roughness, and bioactivity of implant surfaces are reviewed. In addition, macro-scale methods (e.g., [...] Read more.

The propose of this review was to summarize the advances in multi-scale surface technology of titanium implants to accelerate the osseointegration process. The several multi-scaled methods used for improving wettability, roughness, and bioactivity of implant surfaces are reviewed. In addition, macro-scale methods (e.g., 3D printing (3DP) and laser surface texturing (LST)), micro-scale (e.g., grit-blasting, acid-etching, and Sand-blasted, Large-grit, and Acid-etching (SLA)) and nano-scale methods (e.g., plasma-spraying and anodization) are also discussed, and these surfaces are known to have favorable properties in clinical applications. Functionalized coatings with organic and non-organic loadings suggest good prospects for the future of modern biotechnology. Nevertheless, because of high cost and low clinical validation, these partial coatings have not been commercially available so far. A large number of in vitro and in vivo investigations are necessary in order to obtain in-depth exploration about the efficiency of functional implant surfaces. The prospective titanium implants should possess the optimum chemistry, bionic characteristics, and standardized modern topographies to achieve rapid osseointegration. Full article

(This article belongs to the Special Issue Non-cytotoxic Nanoparticles)

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30 pages, 4897 KiB

Open AccessArticle

Dendrimer Nanodevices and Gallic Acid as Novel Strategies to Fight Chemoresistance in Neuroblastoma Cells

by Silvana Alfei, Barbara Marengo, Guendalina Zuccari, Federica Turrini and Cinzia Domenicotti

Nanomaterials 2020, 10(6), 1243; https://doi.org/10.3390/nano10061243 - 26 Jun 2020

Cited by 49 | Viewed by 4676

Abstract

Human neuroblastoma (NB), a pediatric tumor inclined to relapse, after an initial response to therapy, usually develops resistance. Since several chemotherapeutics exert anticancer effect by increasing reactive oxygen species (ROS), NB cells overproduce antioxidant compounds becoming drugs-resistant. A strategy to sensitize NB cells [...] Read more.

Human neuroblastoma (NB), a pediatric tumor inclined to relapse, after an initial response to therapy, usually develops resistance. Since several chemotherapeutics exert anticancer effect by increasing reactive oxygen species (ROS), NB cells overproduce antioxidant compounds becoming drugs-resistant. A strategy to sensitize NB cells to chemotherapy involves reducing their antioxidant defenses and inducing ROS overproduction. Concerning this, although affected by several issues that limit their clinical application, antioxidant/pro-oxidant polyphenols, such as gallic acid (GA), showed pro-oxidant anti-cancer effects and low toxicity for healthy cells, in several kind of tumors, not including NB. Herein, for the first time, free GA, two GA-dendrimers, and the dendrimer adopted as GA reservoir were tested on both sensitive and chemoresistant NB cells. The dendrimer device, administered at the dose previously found active versus sensitive NB cells, induced ROS-mediated death also in chemoresistant cells. Free GA proved a dose-dependent ROS-mediated cytotoxicity on both cell populations. Intriguingly, when administered in dendrimer formulations at a dose not cytotoxic for NB cells, GA nullified any pro-oxidant activity of dendrimer. Unfortunately, due to GA, nanoformulations were inactive on NB cells, but GA resized in nanoparticles showed considerable ability in counteracting, at low dose, ROS production and oxidative stress, herein induced by the dendrimer. Full article

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

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12 pages, 3027 KiB

Open AccessArticle

Subwavelength Silicon Nanoblocks for Directional Emission Manipulation

by Tianyue Zhang, Xuewei Li, Jian Xu, Xiaoming Zhang, Zi-Lan Deng and Xiangping Li

Nanomaterials 2020, 10(6), 1242; https://doi.org/10.3390/nano10061242 - 26 Jun 2020

Cited by 5 | Viewed by 3402

Abstract

Manipulating the light emission direction and boosting its directivity have essential importance in integrated nanophotonic devices. Here, we theoretically propose a single dielectric silicon nanoblock as an efficient, multifunctional and ultracompact all-dielectric nanoantenna to direct light into a preferential direction. Unidirectional scattering of [...] Read more.

Manipulating the light emission direction and boosting its directivity have essential importance in integrated nanophotonic devices. Here, we theoretically propose a single dielectric silicon nanoblock as an efficient, multifunctional and ultracompact all-dielectric nanoantenna to direct light into a preferential direction. Unidirectional scattering of a plane wave as well as switchable directive emission fed by a localized emitter are demonstrated within the nanoantenna. The high directionalities are revealed to originate from a variety of mechanisms that can coexist within a single nanoblock, which contribute to the far-field radiation patterns of the outcoming light, thanks to the wealth of multipolar electric and magnetic resonances. The efficient beam redirections are also observed, which are sensitive to the local configurations of the emitter antenna coupled system. The designed antenna, with extreme geometry simplicity, ultracompact and low-loss features, could be favorable for highly sensitive sensing as well as applications in optical nanocircuits. Full article

(This article belongs to the Special Issue 10th Anniversary of Nanomaterials—Recent Advances in Nanophotonics: Characterization, Modelling, and Nanodevices)

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21 pages, 6055 KiB

Open AccessArticle

Effect of Chemical Solvents on the Wetting Behavior Over Time of Femtosecond Laser Structured Ti6Al4V Surfaces

by Georg Schnell, Christian Polley, Stephan Bartling and Hermann Seitz

Nanomaterials 2020, 10(6), 1241; https://doi.org/10.3390/nano10061241 - 26 Jun 2020

Cited by 35 | Viewed by 4438

Abstract

The effect of chemical solvents on the wetting state of laser-structured surfaces over time is systematically examined in this paper. By using a 300-fs laser, nanostructures were generated on Ti6Al4V, subsequently cleaned in an ultrasonic bath with different solvents and stored in ambient [...] Read more.

The effect of chemical solvents on the wetting state of laser-structured surfaces over time is systematically examined in this paper. By using a 300-fs laser, nanostructures were generated on Ti6Al4V, subsequently cleaned in an ultrasonic bath with different solvents and stored in ambient air. The static contact angle showed significant differences for cleaning with various solvents, which, depending on the applied cleaning and time, amounted up to 100°. X-ray photoelectron spectroscopy analyses reveal that the cleaning of the laser-structured surfaces affects the surface chemistry and the aging behavior of the surfaces, even with highly volatile solvents. The effect of the chemical surface modification is particularly noticeable when using alcohols for cleaning, which, due to their OH groups, cause highly hydrophilic behavior of the surface after one day of storage. Over the course of 14 days, enrichment with organic groups from the atmosphere occurs on the surface, which leads to poorer wetting on almost every structured surface. In contrast, the cleaning in hexane leads to a fast saturation of the surface with long-chain carbon groups and thus to a time-independent hydrophobic behavior. Full article

(This article belongs to the Special Issue Multifunctional 2D and 3D Nano and Microtextured Interfaces: From Medical to Environmental and Sensing Applications)

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11 pages, 4849 KiB

Open AccessArticle

Detection of C-Reactive Protein Using Histag-HRP Functionalized Nanoconjugate with Signal Amplified Immunoassay

by Mohd Farhan Siddiqui, Zeeshan Ahmad Khan and Seungkyung Park

Nanomaterials 2020, 10(6), 1240; https://doi.org/10.3390/nano10061240 - 26 Jun 2020

Cited by 12 | Viewed by 4076

Abstract

Ultrasensitive detection of biomarkers is highly significant for disease prognosis and public health treatment. Despite wide acceptance in routine laboratory tests, the conventional enzyme-linked immunosorbent assay (ELISA) has been of limited use for early biomarker detection due to insufficient sensitivity and multiple long [...] Read more.

Ultrasensitive detection of biomarkers is highly significant for disease prognosis and public health treatment. Despite wide acceptance in routine laboratory tests, the conventional enzyme-linked immunosorbent assay (ELISA) has been of limited use for early biomarker detection due to insufficient sensitivity and multiple long incubation time. Several nanoprobes have been introduced to circumvent the limitation, however, rapid, simple, and chemical-free nanoprobe synthesis and sensitive detection methods, particularly for ELISA, are still lacking. In this study, we have synthesized a gold nanoprobe, conjugated with multiple 6X-histidine (6X-his) peptide and nickel-horseradish peroxidase (Ni²⁺-HRP), for enhancing the colorimetric signal in ELISA. The developed nanoprobe has been tested for the detection of immunologically significant C-reactive protein (CRP) in ELISA format. The performance of designed probe is validated by testing standard and serum samples, and the detection limit of 32.0 pg/mL with R² = 0.98 is confirmed. Furthermore, a comparative analysis of the developed nanoprobe was performed with ELISA developed on conventional guidelines, the proposed immunoassay showed an increase of 12-fold sensitivity for detecting CRP due to the high loading of 6Xhis peptide and binding of multiple Ni²⁺-HRP on a gold nanoparticle. Additionally, the proposed assay provides a simple, fast, and cost-efficient (not requiring multiple antibodies) detection of CRP with easy nanoprobe synthesis. Moreover, the developed Histag-HRP functionalized nanoconjugate immunoassay is flexible and can be applied to other biomarkers efficiently by using disease specific antibody. Full article

(This article belongs to the Special Issue Gold Nanoparticle-Based Biosensors)

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12 pages, 5092 KiB

Open AccessArticle

Phonon Bridge Effect in Superlattices of Thermoelectric TiNiSn/HfNiSn With Controlled Interface Intermixing

by Sven Heinz, Emigdio Chavez Angel, Maximilian Trapp, Hans-Joachim Kleebe and Gerhard Jakob

Nanomaterials 2020, 10(6), 1239; https://doi.org/10.3390/nano10061239 - 25 Jun 2020

Cited by 2 | Viewed by 3265

Abstract

The implementation of thermal barriers in thermoelectric materials improves their power conversion rates effectively. For this purpose, material boundaries are utilized and manipulated to affect phonon transmissivity. Specifically, interface intermixing and topography represents a useful but complex parameter for thermal transport modification. This [...] Read more.

The implementation of thermal barriers in thermoelectric materials improves their power conversion rates effectively. For this purpose, material boundaries are utilized and manipulated to affect phonon transmissivity. Specifically, interface intermixing and topography represents a useful but complex parameter for thermal transport modification. This study investigates epitaxial thin film multilayers, so called superlattices (SL), of TiNiSn/HfNiSn, both with pristine and purposefully deteriorated interfaces. High-resolution transmission electron microscopy and X-ray diffractometry are used to characterize their structural properties in detail. A differential 3

ω

-method probes their thermal resistivity. The thermal resistivity reaches a maximum for an intermediate interface quality and decreases again for higher boundary layer intermixing. For boundaries with the lowest interface quality, the interface thermal resistance is reduced by 23% compared to a pristine SL. While an uptake of diffuse scattering likely explains the initial deterioration of thermal transport, we propose a phonon bridge interpretation for the lowered thermal resistivity of the interfaces beyond a critical intermixing. In this picture, the locally reduced acoustic contrast of the less defined boundary acts as a mediator that promotes phonon transition. Full article

(This article belongs to the Special Issue Thermal Transport in Nanostructures and Nanomaterials)

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13 pages, 1811 KiB

Open AccessArticle

Therapeutic Delivery of rAAV sox9 via Polymeric Micelles Counteracts the Effects of Osteoarthritis-Associated Inflammatory Cytokines in Human Articular Chondrocytes

by Jonas Urich, Magali Cucchiarini and Ana Rey-Rico

Nanomaterials 2020, 10(6), 1238; https://doi.org/10.3390/nano10061238 - 25 Jun 2020

Cited by 13 | Viewed by 3407

Abstract

Osteoarthritis (OA) is a prevalent joint disease linked to the irreversible degradation of key extracellular cartilage matrix (ECM) components (proteoglycans, type-II collagen) by proteolytic enzymes due to an impaired tissue homeostasis, with the critical involvement of OA-associated pro-inflammatory cytokines (interleukin 1 beta, i.e., [...] Read more.

Osteoarthritis (OA) is a prevalent joint disease linked to the irreversible degradation of key extracellular cartilage matrix (ECM) components (proteoglycans, type-II collagen) by proteolytic enzymes due to an impaired tissue homeostasis, with the critical involvement of OA-associated pro-inflammatory cytokines (interleukin 1 beta, i.e., IL-1β, and tumor necrosis factor alpha, i.e., TNF-α). Gene therapy provides effective means to re-establish such degraded ECM compounds by rejuvenating the altered OA phenotype of the articular chondrocytes, the unique cell population ubiquitous in the articular cartilage. In particular, overexpression of the highly specialized SOX9 transcription factor via recombinant adeno-associated viral (rAAV) vectors has been reported for its ability to readjust the metabolic balance in OA, in particular via controlled rAAV delivery using polymeric micelles as carriers to prevent a possible vector neutralization by antibodies present in the joints of patients. As little is known on the challenging effects of such naturally occurring OA-associated pro-inflammatory cytokines on such rAAV/polymeric gene transfer, we explored the capacity of polyethylene oxide (PEO) and polypropylene oxide (PPO)-based polymeric micelles to deliver a candidate rAAV-FLAG-hsox9 construct in human OA chondrocytes in the presence of IL-1β and TNF-α. We report that effective, micelle-guided rAAV sox9 overexpression enhanced the deposition of ECM components and the levels of cell survival, while advantageously reversing the deleterious effects afforded by the OA cytokines on these processes. These findings highlight the potentiality of polymeric micelles as effective rAAV controlled delivery systems to counterbalance the specific contribution of major OA-associated inflammatory cytokines, supporting the concept of using such systems for the treatment for chronic inflammatory diseases like OA. Full article

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

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16 pages, 2815 KiB

Open AccessArticle

Exploration of the Interaction Strength at the Interface of Anionic Chalcogen Anchors and Gold (111)-Based Nanomaterials

by Sebastián Miranda-Rojas and Fernando Mendizabal

Nanomaterials 2020, 10(6), 1237; https://doi.org/10.3390/nano10061237 - 25 Jun 2020

Cited by 1 | Viewed by 2281

Abstract

Nowadays, the use of sulfur-based ligands to modify gold-based materials has become a common trend. Here, we present a theoretical exploration of the modulation of the chalcogenides-gold interaction strength, using sulfur, selenium, and tellurium as anchor atoms. To characterize the chalcogenide-gold interaction, we [...] Read more.

Nowadays, the use of sulfur-based ligands to modify gold-based materials has become a common trend. Here, we present a theoretical exploration of the modulation of the chalcogenides-gold interaction strength, using sulfur, selenium, and tellurium as anchor atoms. To characterize the chalcogenide-gold interaction, we designed a nanocluster of 42 gold atoms (Au₄₂) to model a gold surface (111) and a series of 60 functionalized phenyl-chalcogenolate ligands to determine the ability of electron-donor and -withdrawing groups to modulate the interaction. The analysis of the interaction was performed by using energy decomposition analysis (EDA), non-covalent interactions index (NCI), and natural population analysis (NPA) to describe the charge transfer processes and to determine data correlation analyses. The results revealed that the magnitudes of the interaction energies increase following the order S < Se < Te, where this interaction strength can be augmented by electron-donor groups, under the donor-acceptor character the chalcogen–gold interaction. We also found that the functionalization in meta position leads to better control of the interaction strength than the ortho substitution due to the steric and inductive effects involved when functionalized in this position. Full article

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

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16 pages, 2192 KiB

Open AccessArticle

TAO-DFT Study on the Electronic Properties of Diamond-Shaped Graphene Nanoflakes

by Hong-Jui Huang, Sonai Seenithurai and Jeng-Da Chai

Nanomaterials 2020, 10(6), 1236; https://doi.org/10.3390/nano10061236 - 25 Jun 2020

Cited by 12 | Viewed by 4905

Abstract

At the nanoscale, it has been rather troublesome to properly explore the properties associated with electronic systems exhibiting a radical nature using traditional electronic structure methods. Graphene nanoflakes, which are graphene nanostructures of different shapes and sizes, are typical examples. Recently, TAO-DFT (i.e., [...] Read more.

At the nanoscale, it has been rather troublesome to properly explore the properties associated with electronic systems exhibiting a radical nature using traditional electronic structure methods. Graphene nanoflakes, which are graphene nanostructures of different shapes and sizes, are typical examples. Recently, TAO-DFT (i.e., thermally-assisted-occupation density functional theory) has been formulated to tackle such challenging problems. As a result, we adopt TAO-DFT to explore the electronic properties associated with diamond-shaped graphene nanoflakes with n = 2–15 benzenoid rings fused together at each side, designated as n-pyrenes (as they could be expanded from pyrene). For all the n values considered, n-pyrenes are ground-state singlets. With increasing the size of n-pyrene, the singlet-triplet energy gap, vertical ionization potential, and fundamental gap monotonically decrease, while the vertical electron affinity and symmetrized von Neumann entropy (which is a quantitative measure of radical nature) monotonically increase. When n increases, there is a smooth transition from the nonradical character of the smaller n-pyrenes to the increasing polyradical nature of the larger n-pyrenes. Furthermore, the latter is shown to be related to the increasing concentration of active orbitals on the zigzag edges of the larger n-pyrenes. Full article

(This article belongs to the Special Issue Science and Technology of Graphene)

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16 pages, 1638 KiB

Open AccessArticle

Comparative Study of Different Acidic Surface Structures in Solid Catalysts Applied for the Isobutene Dimerization Reaction

by José M. Fernández-Morales, Eva Castillejos, Esther Asedegbega-Nieto, Ana Belén Dongil, Inmaculada Rodríguez-Ramos and Antonio Guerrero-Ruiz

Nanomaterials 2020, 10(6), 1235; https://doi.org/10.3390/nano10061235 - 25 Jun 2020

Cited by 14 | Viewed by 4174

Abstract

Dimerization of isobutene (IBE) to C_8s olefins was evaluated over a range of solid acid catalysts of diverse nature, in a fixed bed reactor working in a continuous mode. All catalytic materials were studied in the title reaction performed between 50–250 °C, [...] Read more.

Dimerization of isobutene (IBE) to C_8s olefins was evaluated over a range of solid acid catalysts of diverse nature, in a fixed bed reactor working in a continuous mode. All catalytic materials were studied in the title reaction performed between 50–250 °C, being the reaction feed a mixture of IBE/helium (4:1 molar ratio). In all materials, both conversion and selectivity increased with increasing reaction temperature and at 180 °C the best performance was recorded. Herein, we used thermogravimetry analysis (TGA) and temperature programmed desorption of adsorbed ammonia (NH₃-TPD) for catalysts characterization. We place emphasis on the nature of acid sites that affect the catalytic performance. High selectivity to C_8s was achieved with all catalysts. Nicely, the catalyst with higher loading of Brønsted sites displayed brilliant catalytic performance in the course of the reaction (high IBE conversion). However, optimum selectivity towards C₈ compounds led to low catalyst stability, this being attributed to the combined effect between the nature of acidic sites and structural characteristics of the catalytic materials used. Therefore, this study would foment more research in the optimization of the activity and the selectivity for IBE dimerization reactions. Full article

(This article belongs to the Special Issue Application of New Nanoparticle Structures as Catalysts)

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29 pages, 2579 KiB

Open AccessReview

Nanoparticle-Based Therapeutic Approach for Diabetic Wound Healing

by Hariharan Ezhilarasu, Dinesh Vishalli, S. Thameem Dheen, Boon-Huat Bay and Dinesh Kumar Srinivasan

Nanomaterials 2020, 10(6), 1234; https://doi.org/10.3390/nano10061234 - 25 Jun 2020

Cited by 107 | Viewed by 12866

Abstract

Diabetes mellitus (DM) is a common endocrine disease characterized by a state of hyperglycemia (higher level of glucose in the blood than usual). DM and its complications can lead to diabetic foot ulcer (DFU). DFU is associated with impaired wound healing, due to [...] Read more.

Diabetes mellitus (DM) is a common endocrine disease characterized by a state of hyperglycemia (higher level of glucose in the blood than usual). DM and its complications can lead to diabetic foot ulcer (DFU). DFU is associated with impaired wound healing, due to inappropriate cellular and cytokines response, infection, poor vascularization, and neuropathy. Effective therapeutic strategies for the management of impaired wound could be attained through a better insight of molecular mechanism and pathophysiology of diabetic wound healing. Nanotherapeutics-based agents engineered within 1–100 nm levels, which include nanoparticles and nanoscaffolds, are recent promising treatment strategies for accelerating diabetic wound healing. Nanoparticles are smaller in size and have high surface area to volume ratio that increases the likelihood of biological interaction and penetration at wound site. They are ideal for topical delivery of drugs in a sustained manner, eliciting cell-to-cell interactions, cell proliferation, vascularization, cell signaling, and elaboration of biomolecules necessary for effective wound healing. Furthermore, nanoparticles have the ability to deliver one or more therapeutic drug molecules, such as growth factors, nucleic acids, antibiotics, and antioxidants, which can be released in a sustained manner within the target tissue. This review focuses on recent approaches in the development of nanoparticle-based therapeutics for enhancing diabetic wound healing. Full article

(This article belongs to the Special Issue Recent Progress in Antimicrobial Nanomaterials)

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18 pages, 5568 KiB

Open AccessReview

A Review of the Effect of a Nanostructured Thin Film Formed by Titanium Carbide and Titanium Oxides Clustered around Carbon in Graphitic Form on Osseointegration

by Roberto Scandurra, Anna Scotto d’Abusco and Giovanni Longo

Nanomaterials 2020, 10(6), 1233; https://doi.org/10.3390/nano10061233 - 24 Jun 2020

Cited by 9 | Viewed by 2820

Abstract

Improving the biocompatibility of implants is an extremely important step towards improving their quality. In this review, we recount the technological and biological process for coating implants with thin films enriched in titanium carbide (TiC), which provide improved cell growth and osseointegration. At [...] Read more.

Improving the biocompatibility of implants is an extremely important step towards improving their quality. In this review, we recount the technological and biological process for coating implants with thin films enriched in titanium carbide (TiC), which provide improved cell growth and osseointegration. At first, we discuss the use of a Pulsed Laser Ablation Deposition, which produced films with a good biocompatibility, cellular stimulation and osseointegration. We then describe how Ion Plating Plasma Assisted technology could be used to produce a nanostructured layer composed by graphitic carbon, whose biocompatibility is enhanced by titanium oxides and titanium carbide. In both cases, the nanostructured coating was compact and strongly bound to the bulk titanium, thus particularly useful to protect implants from the harsh oxidizing environment of biological tissues. The morphology and chemistry of the nanostructured coating were particularly desirable for osteoblasts, resulting in improved proliferation and differentiation. The cellular adhesion to the TiC-coated substrates was much stronger than to uncoated surfaces, and the number of philopodia and lamellipodia developed by the cells grown on the TiC-coated samples was higher. Finally, tests performed on rabbits confirmed in vivo that the osseointegration process of the TiC-coated implants is more efficient than that of uncoated titanium implants. Full article

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

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30 pages, 4446 KiB

Open AccessReview

Nutraceutical Vegetable Oil Nanoformulations for Prevention and Management of Diseases

by Cristian Vergallo

Nanomaterials 2020, 10(6), 1232; https://doi.org/10.3390/nano10061232 - 24 Jun 2020

Cited by 27 | Viewed by 6350

Abstract

The scientific community is becoming increasingly interested in identifying, characterizing, and delivering nutraceuticals, which constitutes a multi-billion-dollar business. These bioactive agents are claimed to exhibit several health benefits, including the prevention and treatment of diseases such as arthritis, cancer, osteoporosis, cataracts, Alzheimer’s, and [...] Read more.

The scientific community is becoming increasingly interested in identifying, characterizing, and delivering nutraceuticals, which constitutes a multi-billion-dollar business. These bioactive agents are claimed to exhibit several health benefits, including the prevention and treatment of diseases such as arthritis, cancer, osteoporosis, cataracts, Alzheimer’s, and Huntington’s diseases, heart, brain and metabolic disorders, etc. Nutraceuticals are typically consumed as part of a regular human diet and are usually present within foods, comprising vegetable oil, although at low levels and variable composition. Thus, it is difficult to control the type, amount and frequency of their ingestion by individuals. Nanoformulations about vegetable oil-based bioactive compounds with nutraceutical properties are useful for overcoming these issues, while improving the uptake, absorption, and bioavailability in the body. The purpose of this current study is to review papers on such nanoformulations, particularly those relevant for health benefits and the prevention and management of diseases, as well as bioactives extracted from vegetable oils enhancing the drug effectiveness, retrieved through bibliographic databases by setting a timespan from January 2000 to April 2020 (about 1758 records). Full article

(This article belongs to the Special Issue Nanonutraceuticals Delivery)

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15 pages, 5949 KiB

Open AccessReview

Self-Assembly of Magnetic Nanoparticles in Ferrofluids on Different Templates Investigated by Neutron Reflectometry

by Katharina Theis-Bröhl, Apurve Saini, Max Wolff, Joseph A. Dura, Brian B. Maranville and Julie A. Borchers

Nanomaterials 2020, 10(6), 1231; https://doi.org/10.3390/nano10061231 - 24 Jun 2020

Cited by 16 | Viewed by 4768

Abstract

In this article we review the process by which magnetite nanoparticles self-assemble onto solid surfaces. The focus is on neutron reflectometry studies providing information on the density and magnetization depth profiles of buried interfaces. Specific attention is given to the near-interface "wetting" layer [...] Read more.

In this article we review the process by which magnetite nanoparticles self-assemble onto solid surfaces. The focus is on neutron reflectometry studies providing information on the density and magnetization depth profiles of buried interfaces. Specific attention is given to the near-interface "wetting" layer and to examples of magnetite nanoparticles on a hydrophilic silicon crystal, one coated with (3-Aminopropyl)triethoxysilane, and finally, one with a magnetic film with out-of-plane magnetization. Full article

(This article belongs to the Special Issue Characterization of Nanostructured Magnetic Materials Using Neutron Scattering Techniques)

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30 pages, 4176 KiB

Open AccessReview

Recent Advances in Surface Nanoengineering for Biofilm Prevention and Control. Part I: Molecular Basis of Biofilm Recalcitrance. Passive Anti-Biofouling Nanocoatings

by Paul Cătălin Balaure and Alexandru Mihai Grumezescu

Nanomaterials 2020, 10(6), 1230; https://doi.org/10.3390/nano10061230 - 24 Jun 2020

Cited by 42 | Viewed by 5351

Abstract

Medical device-associated infections are becoming a leading cause of morbidity and mortality worldwide, prompting researchers to find new, more effective ways to control the bacterial colonisation of surfaces and biofilm development. Bacteria in biofilms exhibit a set of “emergent properties”, meaning those properties [...] Read more.

Medical device-associated infections are becoming a leading cause of morbidity and mortality worldwide, prompting researchers to find new, more effective ways to control the bacterial colonisation of surfaces and biofilm development. Bacteria in biofilms exhibit a set of “emergent properties”, meaning those properties that are not predictable from the study of free-living bacterial cells. The social coordinated behaviour in the biofilm lifestyle involves intricate signaling pathways and molecular mechanisms underlying the gain in resistance and tolerance (recalcitrance) towards antimicrobial agents as compared to free-floating bacteria. Nanotechnology provides powerful tools to disrupt the processes responsible for recalcitrance development in all stages of the biofilm life cycle. The present paper is a state-of-the-art review of the surface nanoengineering strategies currently used to design antibiofilm coatings. The review is structurally organised in two parts according to the targeted biofilm life cycle stages and molecular mechanisms intervening in recalcitrance development. Therefore, in the present first part, we begin with a presentation of the current knowledge of the molecular mechanisms responsible for increased recalcitrance that have to be disrupted. Further, we deal with passive surface nanoengineering strategies that aim to prevent bacterial cells from settling onto a biotic or abiotic surface. Both “fouling-resistant” and “fouling release” strategies are addressed as well as their synergic combination in a single unique nanoplatform. Full article

(This article belongs to the Special Issue Antibacterial Nanomaterials Coating: Fabrication and Applications)

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22 pages, 1119 KiB

Open AccessReview

Translating Scientific Advances in the AOP Framework to Decision Making for Nanomaterials

by James D. Ede, Vladimir Lobaskin, Ulla Vogel, Iseult Lynch, Sabina Halappanavar, Shareen H. Doak, Megan G. Roberts and Jo Anne Shatkin

Nanomaterials 2020, 10(6), 1229; https://doi.org/10.3390/nano10061229 - 24 Jun 2020

Cited by 32 | Viewed by 7234

Abstract

Much of the current innovation in advanced materials is occurring at the nanoscale, specifically in manufactured nanomaterials (MNs). MNs display unique attributes and behaviors, and may be biologically and physically unique, making them valuable across a wide range of applications. However, as the [...] Read more.

Much of the current innovation in advanced materials is occurring at the nanoscale, specifically in manufactured nanomaterials (MNs). MNs display unique attributes and behaviors, and may be biologically and physically unique, making them valuable across a wide range of applications. However, as the number, diversity and complexity of MNs coming to market continue to grow, assessing their health and environmental risks with traditional animal testing approaches is too time- and cost-intensive to be practical, and is undesirable for ethical reasons. New approaches are needed that meet current requirements for regulatory risk assessment while reducing reliance on animal testing and enabling safer-by-design product development strategies to be implemented. The adverse outcome pathway (AOP) framework presents a sound model for the advancement of MN decision making. Yet, there are currently gaps in technical and policy aspects of AOPs that hinder the adoption and use for MN risk assessment and regulatory decision making. This review outlines the current status and next steps for the development and use of the AOP framework in decision making regarding the safety of MNs. Opportunities and challenges are identified concerning the advancement and adoption of AOPs as part of an integrated approach to testing and assessing (IATA) MNs, as are specific actions proposed to advance the development, use and acceptance of the AOP framework and associated testing strategies for MN risk assessment and decision making. The intention of this review is to reflect the views of a diversity of stakeholders including experts, researchers, policymakers, regulators, risk assessors and industry representatives on the current status, needs and requirements to facilitate the future use of AOPs in MN risk assessment. It incorporates the views and feedback of experts that participated in two workshops hosted as part of an Organization for Economic Cooperation and Development (OECD) Working Party on Manufactured Nanomaterials (WPMN) project titled, “Advancing AOP Development for Nanomaterial Risk Assessment and Categorization”, as well as input from several EU-funded nanosafety research consortia. Full article

(This article belongs to the Special Issue From Nanoinformatics to Nanomaterials Risk Assessment and Governance)

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13 pages, 2877 KiB

Open AccessArticle

Organic Functionalized Graphene Oxide Behavior in Water

by Changwoo Kim, Junseok Lee, Will Wang and John Fortner

Nanomaterials 2020, 10(6), 1228; https://doi.org/10.3390/nano10061228 - 24 Jun 2020

Cited by 14 | Viewed by 3171

Abstract

Surface modified graphene oxide (GO) has received broad interest as a potential platform material for sensors, membranes, and sorbents, among other environmental applications. However, compared to parent (unmodified) GO, there is a dearth of information regarding the behavior of subsequently (secondary) modified GO, [...] Read more.

Surface modified graphene oxide (GO) has received broad interest as a potential platform material for sensors, membranes, and sorbents, among other environmental applications. However, compared to parent (unmodified) GO, there is a dearth of information regarding the behavior of subsequently (secondary) modified GO, other than bulk natural organic matter (NOM) coating(s). Here, we systematically explore the critical role of organic functionalization with respect to GO stability in water. Specifically, we synthesized a matrix of GO-based materials considering a carefully chosen range of bound organic molecules (hydrophobic coatings: propylamine, tert-octylamine, and 1-adamantylamine; hydrophilic coatings: 3-amino-1-propanol and 3-amino-1-adamantanol), so that chemical structures and functional groups could be directly compared. GO (without organic functionalization) with varying oxidation extent(s) was also included for comparison. The material matrix was evaluated for aqueous stability by comparing critical coagulation concentration (CCC) as a function of varied ionic strength and type (NaCl, CaCl₂, MgCl₂, and MgSO₄) at pH 7.0. Without surface derivatization (i.e., pristine GO), increased stability was observed with an increase in the GO oxidation state, which is supported by plate–plate Derjaguin, Landau, Verwey and Overbeek (DLVO) energy interaction analyses. For derivatized GO, we observed that hydrophilic additions (phi-GO) are relatively more stable than hydrophobic organic coated GO (pho-GO). We further explored this by altering a single OH group in the adamantane-x structure (3-amino-1-adamantanol vs. 1-adamantylamine). As expected, Ca²⁺ and monovalent co-ions play an important role in the aggregation of highly oxidized GO (HGO) and phi-GO, while the effects of divalent cations and co-ions were less significant for pho-GO. Taken together, this work provides new insight into the intricate dynamics of GO-based material stability in water as it relates to surface functionalization (surface energies) and ionic conditions including type of co- and counter-ion, valence, and concentration. Full article

(This article belongs to the Special Issue Surface Modifications of Carbon Nanomaterials)

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17 pages, 5982 KiB

Open AccessArticle

Congo Red Decolorization Using Textile Filters and Laccase-Based Nanocomposites in Continuous Flow Bioreactors

by Natalia Lopez-Barbosa, Sergio Leonardo Florez, Juan C. Cruz, Nancy Ornelas-Soto and Johann F. Osma

Nanomaterials 2020, 10(6), 1227; https://doi.org/10.3390/nano10061227 - 24 Jun 2020

Cited by 16 | Viewed by 4638

Abstract

Removal of azo and diazo dye content from textile industry wastewaters is crucial due to their environmental impact. Here, we report on the use of the fungal laccase from Pycnoporus sanguineus CS43 immobilized on silica nanoparticles and entrapped in textile-based filters for the [...] Read more.

Removal of azo and diazo dye content from textile industry wastewaters is crucial due to their environmental impact. Here, we report on the use of the fungal laccase from Pycnoporus sanguineus CS43 immobilized on silica nanoparticles and entrapped in textile-based filters for the degradation of Congo Red. Laccase immobilization and synthesis of the nanocomposites were carried out by two different methods, one in the presence of acetone and the second using water as solvent. This led to a change in the hydrophobicity of the obtained biofilters. Successful preparation of the nanocomposites was confirmed via FTIR spectroscopy. Changes in the secondary structure of the enzyme were inspected through the second derivative of the FTIR spectra. Six different types of filter were fabricated and tested in a continuous flow bioreactor in terms of their decolorization capabilities of Congo Red. The results indicate removal efficiencies that approached 40% for enzymes immobilized on the more hydrophobic supports. Backscattered electron (BSE) images of the different filters were obtained before and after the decolorization process. Percentage of decolorization and activity loss were determined as a function of time until a plateau in decolorization activity was reached. Experimental data was used to recreate the decolorization process in COMSOL Multiphysics^® (Stockholm, Sweden). These simulations were used to determine the proper combination of parameters to maximize decolorization. Our findings suggest that the treatment of textile-based filters with immobilized laccase in conjunction with hydrophobic nanocomposites provides a suitable avenue to achieve more efficient laccase dye decolorization (39%) than that obtained with similar filters treated only with free laccase (8%). Filters treated with silica-based nanocomposites and immobilized laccases showed an increase in their decolorization capability, probably due to changes in their wetting phenomena. Full article

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40 pages, 4508 KiB

Open AccessReview

Emergence of Impurity-Doped Nanocrystal Light-Emitting Diodes

by Dongxiang Luo, Lin Wang, Ying Qiu, Runda Huang and Baiquan Liu

Nanomaterials 2020, 10(6), 1226; https://doi.org/10.3390/nano10061226 - 24 Jun 2020

Cited by 14 | Viewed by 5605

Abstract

In recent years, impurity-doped nanocrystal light-emitting diodes (LEDs) have aroused both academic and industrial interest since they are highly promising to satisfy the increasing demand of display, lighting, and signaling technologies. Compared with undoped counterparts, impurity-doped nanocrystal LEDs have been demonstrated to possess [...] Read more.

In recent years, impurity-doped nanocrystal light-emitting diodes (LEDs) have aroused both academic and industrial interest since they are highly promising to satisfy the increasing demand of display, lighting, and signaling technologies. Compared with undoped counterparts, impurity-doped nanocrystal LEDs have been demonstrated to possess many extraordinary characteristics including enhanced efficiency, increased luminance, reduced voltage, and prolonged stability. In this review, recent state-of-the-art concepts to achieve high-performance impurity-doped nanocrystal LEDs are summarized. Firstly, the fundamental concepts of impurity-doped nanocrystal LEDs are presented. Then, the strategies to enhance the performance of impurity-doped nanocrystal LEDs via both material design and device engineering are introduced. In particular, the emergence of three types of impurity-doped nanocrystal LEDs is comprehensively highlighted, namely impurity-doped colloidal quantum dot LEDs, impurity-doped perovskite LEDs, and impurity-doped colloidal quantum well LEDs. At last, the challenges and the opportunities to further improve the performance of impurity-doped nanocrystal LEDs are described. Full article

(This article belongs to the Special Issue Low-Dimensional Nanomaterials for Photonics and Optoelectronics)

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20 pages, 3928 KiB

Open AccessArticle

Ultraviolet Photodetection Based on High-Performance Co-Plus-Ni Doped ZnO Nanorods Grown by Hydrothermal Method on Transparent Plastic Substrate

by Hafiz Muhammad Salman Ajmal, Fasihullah Khan, Kiyun Nam, Hae Young Kim and Sam Dong Kim

Nanomaterials 2020, 10(6), 1225; https://doi.org/10.3390/nano10061225 - 23 Jun 2020

Cited by 47 | Viewed by 3814

Abstract

A growth scheme at a low processing temperature for high crystalline-quality of ZnO nanostructures can be a prime stepping stone for the future of various optoelectronic devices manufactured on transparent plastic substrates. In this study, ZnO nanorods (NRs) grown by the hydrothermal method [...] Read more.

A growth scheme at a low processing temperature for high crystalline-quality of ZnO nanostructures can be a prime stepping stone for the future of various optoelectronic devices manufactured on transparent plastic substrates. In this study, ZnO nanorods (NRs) grown by the hydrothermal method at 150 °C through doping of transition metals (TMs), such as Co, Ni, or Co-plus-Ni, on polyethylene terephthalate substrates were investigated by various surface analysis methods. The TM dopants in ZnO NRs suppressed the density of various native defect-states as revealed by our photoluminescence and X-ray photoelectron spectroscopy analysis. Further investigation also showed the doping into ZnO NRs brought about a clear improvement in carrier mobility from 0.81 to 3.95 cm²/V-s as well as significant recovery in stoichiometric contents of oxygen. Ultra-violet photodetectors fabricated with Co-plus-Ni codoped NRs grown on an interdigitated electrode structure exhibited a high spectral response of ~137 A/W, on/off current ratio of ~135, and an improvement in transient response speed with rise-up and fall-down times of ~2.2 and ~3.1 s, respectively. Full article

(This article belongs to the Special Issue ZnO Based Nanostructures: Synthesis, Characterization and Applications)

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15 pages, 5352 KiB

Open AccessArticle

Role of Synthetic Parameters on the Structural and Optical Properties of N,Sn-Copromoted Nanostructured TiO₂: A Combined Ti K-Edge and Sn L_2,3-Edges X-ray Absorption Investigation

by Martina Fracchia, Paolo Ghigna, Alessandro Minguzzi, Alberto Vertova, Francesca Turco, Giuseppina Cerrato and Daniela Meroni

Nanomaterials 2020, 10(6), 1224; https://doi.org/10.3390/nano10061224 - 23 Jun 2020

Cited by 8 | Viewed by 3264

Abstract

Sn-modification of TiO₂ photocatalysts has been recently proposed as a suitable strategy to improve pollutant degradation as well as hydrogen production. In particular, visible light activity could be promoted by doping with Sn²⁺ species, which are, however, thermally unstable. Co-promotion with [...] Read more.

Sn-modification of TiO₂ photocatalysts has been recently proposed as a suitable strategy to improve pollutant degradation as well as hydrogen production. In particular, visible light activity could be promoted by doping with Sn²⁺ species, which are, however, thermally unstable. Co-promotion with N and Sn has been shown to lead to synergistic effects in terms of visible light activity, but the underlying mechanism has, so far, been poorly understood due to the system complexity. Here, the structural, optical, and electronic properties of N,Sn-copromoted, nanostructured TiO₂ from sol-gel synthesis were investigated: the Sn/Ti molar content was varied in the 0–20% range and different post-treatments (calcination and low temperature hydrothermal treatment) were adopted in order to promote the sample crystallinity. Depending on the adopted post-treatment, the optical properties present notable differences, which supports a combined role of Sn dopants and N-induced defects in visible light absorption. X-ray absorption spectroscopy at the Ti K-edge and Sn L_2,3-edges shed light onto the electronic properties and structure of both Ti and Sn species, evidencing a marked difference at the Sn L_2,3-edges between the samples with 20% and 5% Sn/Ti ratio, showing, in the latter case, the presence of tin in a partially reduced state. Full article

(This article belongs to the Special Issue Synchrotron Radiation Techniques for the Investigation of Nanomaterials)

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18 pages, 6760 KiB

Open AccessArticle

Identification of a Profile of Neutrophil-Derived Granule Proteins in the Surface of Gold Nanoparticles after Their Interaction with Human Breast Cancer Sera

by María del Pilar Chantada-Vázquez, María García-Vence, Sergio Vázquez-Estévez, Susana B. Bravo and Cristina Núñez

Nanomaterials 2020, 10(6), 1223; https://doi.org/10.3390/nano10061223 - 23 Jun 2020

Cited by 12 | Viewed by 3532

Abstract

It is well known that the interaction of a nanomaterial with a biological fluid leads to the formation of a protein corona (PC) surrounding the nanomaterial. Using standard blood analyses, alterations in protein patterns are difficult to detect. PC acts as a “nano-concentrator” [...] Read more.

It is well known that the interaction of a nanomaterial with a biological fluid leads to the formation of a protein corona (PC) surrounding the nanomaterial. Using standard blood analyses, alterations in protein patterns are difficult to detect. PC acts as a “nano-concentrator” of serum proteins with affinity for nanoparticles’ surface. Consequently, characterization of PC could allow detection of otherwise undetectable changes in protein concentration at an early stage of a disease, such as breast cancer (BC). Here, we employed gold nanoparticles (AuNPs_diameter: 10.02 ± 0.91 nm) as an enrichment platform to analyze the human serum proteome of BC patients (n = 42) and healthy controls (n = 42). Importantly, the analysis of the PC formed around AuNPs after their interaction with serum samples of BC patients showed a profile of proteins that could differentiate breast cancer patients from healthy controls. These proteins developed a significant role in the immune and/or innate immune system, some of them being neutrophil-derived granule proteins. The analysis of the PC also revealed serum proteome alterations at the subtype level. Full article

(This article belongs to the Special Issue Nanoparticles for Medical Applications: Progress in Surface Modification)

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8 pages, 1512 KiB

Open AccessCommunication

Near-Infrared Rewritable, Non-Volatile Subwavelength Absorber Based on Chalcogenide Phase Change Materials

by Jianfa Zhang, Yiqiong Zhang, Qilin Hong, Wei Xu, Zhihong Zhu and Xiaodong Yuan

Nanomaterials 2020, 10(6), 1222; https://doi.org/10.3390/nano10061222 - 23 Jun 2020

Cited by 19 | Viewed by 3529

Abstract

Chalcogenide phase change materials enable the realization of novel, non-volatile, switchable electronic and photonic devices. In this paper, we propose a type of rewritable, non-volatile near infrared subwavelength absorber based on chalcogenide phase change materials. Our numerical simulations show that nearly perfect absorption [...] Read more.

Chalcogenide phase change materials enable the realization of novel, non-volatile, switchable electronic and photonic devices. In this paper, we propose a type of rewritable, non-volatile near infrared subwavelength absorber based on chalcogenide phase change materials. Our numerical simulations show that nearly perfect absorption more than 0.99 can be realized in the written state while the absorption of as-deposited or erased state is lower than 0.15 in the studied spectral range, leading to high contrast ratio of reflection more than 20 dB. Continuous tuning of the absorption spectra can be realized not only by varying the geometric parameters of the absorber but also by changing the crystallization ratio of the switched Ge

_{2}

Sb

_{2}

Te

_{5}

(GST). The proposed device may find widespread applications in optical modulation, beam steering and so on. Full article

(This article belongs to the Special Issue 10th Anniversary of Nanomaterials—Recent Advances in Nanophotonics: Characterization, Modelling, and Nanodevices)

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19 pages, 12150 KiB

Open AccessArticle

Structure–Properties Relationship of Electrospun PVDF Fibers

by Klara Castkova, Jaroslav Kastyl, Dinara Sobola, Josef Petrus, Eva Stastna, David Riha and Pavel Tofel

Nanomaterials 2020, 10(6), 1221; https://doi.org/10.3390/nano10061221 - 23 Jun 2020

Cited by 68 | Viewed by 6571

Abstract

Electrospinning as a versatile technique producing nanofibers was employed to study the influence of the processing parameters and chemical and physical parameters of solutions on poly(vinylidene fluoride) (PVDF) fibers’ morphology, crystallinity, phase composition and dielectric and piezoelectric characteristics. PVDF fibrous layers with nano- [...] Read more.

Electrospinning as a versatile technique producing nanofibers was employed to study the influence of the processing parameters and chemical and physical parameters of solutions on poly(vinylidene fluoride) (PVDF) fibers’ morphology, crystallinity, phase composition and dielectric and piezoelectric characteristics. PVDF fibrous layers with nano- and micro-sized fiber diameters were prepared by a controlled and reliable electrospinning process. The fibers with diameters from 276 nm to 1392 nm were spun at a voltage of 25 kV–50 kV from the pure PVDF solutions or in the presence of a surfactant—Hexadecyltrimethylammonium bromide (CTAB). Although the presence of the CTAB decreased the fibers’ diameter and increased the electroactive phase content, the piezoelectric performance of the PVDF material was evidently deteriorated. The maximum piezoelectric activity was achieved in the fibrous PVDF material without the use of the surfactant, when a piezoelectric charge of 33 pC N⁻¹ was measured in the transversal direction on a mean fiber diameter of 649 nm. In this direction, the material showed a higher piezoelectric activity than in the longitudinal direction. Full article

(This article belongs to the Special Issue Stimuli-Responsive Nanosystems Based on Polymers and Hybrid Nanoparticles)

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11 pages, 3090 KiB

Open AccessArticle

Cinnamon-Derived Hierarchically Porous Carbon as an Effective Lithium Polysulfide Reservoir in Lithium–Sulfur Batteries

by Ranjith Thangavel, Aravindaraj G. Kannan, Rubha Ponraj, Karthikeyan Kaliyappan, Won-Sub Yoon, Dong-Won Kim and Yun-Sung Lee

Nanomaterials 2020, 10(6), 1220; https://doi.org/10.3390/nano10061220 - 22 Jun 2020

Cited by 22 | Viewed by 3538

Abstract

Lithium–sulfur batteries are attractive candidates for next generation high energy applications, but more research works are needed to overcome their current challenges, namely: (a) the poor electronic conductivity of sulfur, and (b) the dissolution and migration of long-chain polysulfides. Inspired by eco-friendly and [...] Read more.

Lithium–sulfur batteries are attractive candidates for next generation high energy applications, but more research works are needed to overcome their current challenges, namely: (a) the poor electronic conductivity of sulfur, and (b) the dissolution and migration of long-chain polysulfides. Inspired by eco-friendly and bio-derived materials, we synthesized highly porous carbon from cinnamon sticks. The bio-carbon had an ultra-high surface area and large pore volume, which serves the dual functions of making sulfur particles highly conductive and acting as a polysulfide reservoir. Sulfur was predominantly impregnated into pores of the carbon, and the inter-connected hierarchical pore structure facilitated a faster ionic transport. The strong carbon framework maintained structural integrity upon volume expansion, and the unoccupied pores served as polysulfide trapping sites, thereby retaining the polysulfide within the cathode and preventing sulfur loss. These mechanisms contributed to the superior performance of the lithium-sulfur cell, which delivered a discharge capacity of 1020 mAh g⁻¹ at a 0.2C rate. Furthermore, the cell exhibited improved kinetics, with an excellent cycling stability for 150 cycles with a very low capacity decay of 0.10% per cycle. This strategy of combining all types of pores (micro, meso and macro) with a high pore volume and ultra-high surface area had a synergistic effect on improving the performance of the sulfur cathode. Full article

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

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18 pages, 4092 KiB

Open AccessArticle

Blending Gelatin and Cellulose Nanofibrils: Biocomposites with Tunable Degradability and Mechanical Behavior

by Elisabetta Campodoni, Margherita Montanari, Samuele M. Dozio, Ellinor B. Heggset, Silvia Panseri, Monica Montesi, Anna Tampieri, Kristin Syverud and Monica Sandri

Nanomaterials 2020, 10(6), 1219; https://doi.org/10.3390/nano10061219 - 22 Jun 2020

Cited by 17 | Viewed by 3848

Abstract

Many studies show how biomaterial properties like stiffness, mechanical stimulation and surface topography can influence cellular functions and direct stem cell differentiation. In this work, two different natural materials, gelatin (Gel) and cellulose nanofibrils (CNFs), were combined to design suitable 3D porous biocomposites [...] Read more.

Many studies show how biomaterial properties like stiffness, mechanical stimulation and surface topography can influence cellular functions and direct stem cell differentiation. In this work, two different natural materials, gelatin (Gel) and cellulose nanofibrils (CNFs), were combined to design suitable 3D porous biocomposites for soft-tissue engineering. Gel was selected for its well-assessed high biomimicry that it shares with collagen, from which it derives, while the CNFs were chosen as structural reinforcement because of their exceptional mechanical properties and biocompatibility. Three different compositions of Gel and CNFs, i.e., with weight ratios of 75:25, 50:50 and 25:75, were studied. The biocomposites were morphologically characterized and their total- and macro- porosity assessed, proving their suitability for cell colonization. In general, the pores were larger and more isotropic in the biocomposites compared to the pure materials. The influence of freeze-casting and dehydrothermal treatment (DHT) on mechanical properties, the absorption ability and the shape retention were evaluated. Higher content of CNFs gave higher swelling, and this was attributed to the pore structure. Cross-linking between CNFs and Gel using DHT was confirmed. The Young’s modulus increased significantly by adding the CNFs to Gel with a linear relationship with respect to the CNF amounts. Finally, the biocomposites were characterized in vitro by testing cell colonization and growth through a quantitative cell viability analysis performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, the cell viability analysis was performed by the means of a Live/Dead test with Human mesenchymal stem cells (hMSCs). All the biocomposites had higher cytocompatibility compared to the pure materials, Gel and CNFs. Full article

(This article belongs to the Special Issue Nanocelluloses: Synthesis, Modification and Applications)

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14 pages, 5337 KiB

Open AccessArticle

Antibacterial Character of Cationic Polymers Attached to Carbon-Based Nanomaterials

by Daniela Plachá, Alexandra Muñoz-Bonilla, Kateřina Škrlová, Coro Echeverria, Alberto Chiloeches, Martin Petr, Khalid Lafdi and Marta Fernández-García

Nanomaterials 2020, 10(6), 1218; https://doi.org/10.3390/nano10061218 - 22 Jun 2020

Cited by 21 | Viewed by 3258

Abstract

The preparation of hybrid polymeric systems based on carbon derivatives with a cationic polymer is described. The polymer used is a copolymer of a quaternizable methacrylic monomer with another dopamine-based monomer capable of anchoring to carbon compounds. Graphene oxide and graphene as well [...] Read more.

The preparation of hybrid polymeric systems based on carbon derivatives with a cationic polymer is described. The polymer used is a copolymer of a quaternizable methacrylic monomer with another dopamine-based monomer capable of anchoring to carbon compounds. Graphene oxide and graphene as well as hybrid polymeric systems were widely characterized by infrared, Raman and photoemission X-ray spectroscopies, electron scanning microscopy, zeta potential and thermal degradation. These allowed confirming the attachment of copolymer onto carbonaceous materials. Besides, the antimicrobial activity of hybrid polymeric systems was tested against Gram positive Staphylococcus aureus and Staphylococcus epidermidis and Gram negative Escherichia coli and Pseudomonas aeruginosa bacteria. The results showed the antibacterial character of these hybrid systems. Full article

(This article belongs to the Special Issue Graphene-Related Materials: Synthesis and Applications)

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