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Nanomaterials
Volume 11
Issue 3
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Nanomaterials, Volume 11, Issue 3 (March 2021) – 269 articles

Cover Story (view full-size image): Quantum dots (QDs) are promising nanomaterials for photoluminescence in combination with LEDs, liquid crystal displays, and solar concentrators. However, the optical efficiency of these devices is subjected to the competition between waveguiding and outcoupling. Here, Yera Ussembayev et al. report how tuning the thickness of the QD layer allows controlling the direction of the emitted light. Photoluminescence is entirely outcoupled for monolayers and very thin films, while thicker QD layers waveguide most of the emission toward the edges of the structure. These results offer a new path to boost the efficiency of different light-generating systems. View this paper
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12 pages, 3572 KiB  
Article
Ultrabright Green-Emitting Nanoemulsions Based on Natural Lipids-BODIPY Conjugates
by Xinyue Wang, Sophie Bou, Andrey S. Klymchenko, Nicolas Anton and Mayeul Collot
Nanomaterials 2021, 11(3), 826; https://doi.org/10.3390/nano11030826 - 23 Mar 2021
Cited by 6 | Viewed by 3355
Abstract
Nanoemulsions (NEs) are water-dispersed oil droplets that constitute stealth biocompatible nanomaterials. NEs can reach an impressive degree of fluorescent brightness owing to their oily core that can encapsulate a large number of fluorophores on the condition the latter are sufficiently hydrophobic and oil-soluble. [...] Read more.
Nanoemulsions (NEs) are water-dispersed oil droplets that constitute stealth biocompatible nanomaterials. NEs can reach an impressive degree of fluorescent brightness owing to their oily core that can encapsulate a large number of fluorophores on the condition the latter are sufficiently hydrophobic and oil-soluble. BODIPYs are among the brightest green emitting fluorophores and as neutral molecules possess high lipophilicity. Herein, we synthesized three different natural lipid-BODIPY conjugates by esterification of an acidic BODIPY by natural lipids, namely: α-tocopherol (vitamin E), cholesterol, and stearyl alcohol. The new BODIPY conjugates were characterized in solvents and oils before being encapsulated in NEs at various concentrations. The physical (size, stability over time, leakage) and photophysical properties (absorption and emission wavelength, brightness, photostability) are reported and showed that the nature of the lipid anchor and the nature of the oil used for emulsification greatly influence the properties of the bright NEs. Full article
(This article belongs to the Special Issue Biomedical Applications of Nano-Base Composites)
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19 pages, 5360 KiB  
Article
Advances in the Formulation and Assembly of Non-Cationic Lipid Nanoparticles for the Medical Application of Gene Therapeutics
by Richard K. Fisher III, Phillip C. West, Samuel I. Mattern-Schain, Michael D. Best, Stacy S. Kirkpatrick, Raymond A. Dieter III, Joshua D. Arnold, Michael R. Buckley, Michael M. McNally, Michael B. Freeman, Oscar H. Grandas and Deidra J. H. Mountain
Nanomaterials 2021, 11(3), 825; https://doi.org/10.3390/nano11030825 - 23 Mar 2021
Cited by 8 | Viewed by 4189
Abstract
Lipid nanoparticles have become increasingly popular delivery platforms in the field of gene therapy, but bench-to-bedside success has been limited. Many liposomal gene vectors are comprised of synthetic cationic lipids, which are associated with lipid-induced cytotoxicity and immunogenicity. Natural, non-cationic PEGylated liposomes (PLPs) [...] Read more.
Lipid nanoparticles have become increasingly popular delivery platforms in the field of gene therapy, but bench-to-bedside success has been limited. Many liposomal gene vectors are comprised of synthetic cationic lipids, which are associated with lipid-induced cytotoxicity and immunogenicity. Natural, non-cationic PEGylated liposomes (PLPs) demonstrate favorable biocompatibility profiles but are not considered viable gene delivery vehicles due to inefficient nucleic acid loading and reduced cellular uptake. PLPs can be modified with cell-penetrating peptides (CPPs) to enhance the intracellular delivery of liposomal cargo but encapsulate leakage upon CPP-PLP assembly is problematic. Here, we aimed to identify parameters that overcome these performance barriers by incorporating nucleic acid condensers during CPP-PLP assembly and screening variable ethanol injection parameters for optimization. CPP-PLPs were formed with R8-amphiphiles via pre-insertion, post-insertion and post-conjugation techniques and liposomes were characterized for size, surface charge, homogeneity, siRNA encapsulation efficiency and retention and cell associative properties. Herein we demonstrate that pre-insertion of stearylated R8 into PLPs is an efficient method to produce non-cationic CPP-PLPs and we provide additional assembly parameter specifications for a modified ethanol injection technique that is optimized for siRNA encapsulation/retention and enhanced cell association. This assembly technique could provide improved clinical translation of liposomal based gene therapy applications. Full article
(This article belongs to the Special Issue Progress in Pharmaceutical Applications of Lipid-Based Nanoparticles)
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17 pages, 5633 KiB  
Article
Laminar Pipe Flow with Mixed Convection under the Influence of Magnetic Field
by Johannes Rudl, Christian Hanzelmann, Steffen Feja, Anja Meyer, Annegret Potthoff and Matthias H. Buschmann
Nanomaterials 2021, 11(3), 824; https://doi.org/10.3390/nano11030824 - 23 Mar 2021
Cited by 9 | Viewed by 2428
Abstract
Magnetic influence on ferronanofluid flow is gaining increasing interest from not only the scientific community but also industry. The aim of this study is the examination of the potentials of magnetic forces to control heat transfer. Experiments are conducted to investigate the interaction [...] Read more.
Magnetic influence on ferronanofluid flow is gaining increasing interest from not only the scientific community but also industry. The aim of this study is the examination of the potentials of magnetic forces to control heat transfer. Experiments are conducted to investigate the interaction between four different configurations of permanent magnets and laminar pipe flow with mixed convection. For that purpose a pipe flow test rig is operated with a water-magnetite ferronanofluid. The Reynolds number is varied over one order of magnitude (120–1200). To characterise this suspension, density, solid content, viscosity, thermal conductivity, and specific heat capacity are measured. It is found that, depending on the positioning of the magnet(s) and the Reynolds number, heat transfer is either increased or decreased. The experiments indicate that this is a local effect. After relaxation lengths ranging between 2 and 3.5 lengths of a magnet, all changes disappeared. The conclusion from these findings is that magnetic forces are rather a tool to control heat transfer locally than to enhance the overall heat transfer of heat exchangers or the like. Magnetically caused disturbances decay due to viscous dissipation and the flow approaches the basic state again. Full article
(This article belongs to the Special Issue Colloids and Nanofluids for Energy Management)
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20 pages, 13319 KiB  
Review
Sulvanites: The Promise at the Nanoscale
by Roberto Prado-Rivera, Chen-Yu Chang, Mimi Liu, Cheng-Yu Lai and Daniela R. Radu
Nanomaterials 2021, 11(3), 823; https://doi.org/10.3390/nano11030823 - 23 Mar 2021
Cited by 14 | Viewed by 6183
Abstract
The class of ternary copper chalcogenides Cu3MX4 (M = V, Nb, Ta; X = S, Se, Te), also known as the sulvanite family, has attracted attention in the past decade as featuring promising materials for optoelectronic devices, including solar photovoltaics. [...] Read more.
The class of ternary copper chalcogenides Cu3MX4 (M = V, Nb, Ta; X = S, Se, Te), also known as the sulvanite family, has attracted attention in the past decade as featuring promising materials for optoelectronic devices, including solar photovoltaics. Experimental and theoretical studies of these semiconductors have provided much insight into their properties, both in bulk and at the nanoscale. The recent realization of sulvanites at the nanoscale opens new avenues for the compounds toward printable electronics. This review is aimed at the consideration of synthesis methods, relevant properties and the recent developments of the most important sulvanites. Full article
(This article belongs to the Special Issue Nanocrystals: Synthesis, Properties and Applications)
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13 pages, 5022 KiB  
Article
UV Nanoimprint Lithography: Geometrical Impact on Filling Properties of Nanoscale Patterns
by Christine Thanner and Martin Eibelhuber
Nanomaterials 2021, 11(3), 822; https://doi.org/10.3390/nano11030822 - 23 Mar 2021
Cited by 19 | Viewed by 5344
Abstract
Ultraviolet (UV) Nanoimprint Lithography (NIL) is a replication method that is well known for its capability to address a wide range of pattern sizes and shapes. It has proven to be an efficient production method for patterning resist layers with features ranging from [...] Read more.
Ultraviolet (UV) Nanoimprint Lithography (NIL) is a replication method that is well known for its capability to address a wide range of pattern sizes and shapes. It has proven to be an efficient production method for patterning resist layers with features ranging from a few hundred micrometers and down to the nanometer range. Best results can be achieved if the fundamental behavior of the imprint resist and the pattern filling are considered by the equipment and process parameters. In particular, the material properties and pattern size and shape play a crucial role. For capillary force-driven filling behavior it is important to understand the influencing parameters and respective failure modes in order to optimize the processes for reliable full wafer manufacturing. In this work, the nanoimprint results obtained for different pattern geometries are compared with respect to pattern quality and residual layer thickness: The comprehensive overview of the relevant process parameters is helpful for setting up NIL processes for different nanostructures with minimum layer thickness. Full article
(This article belongs to the Special Issue Nanoimprint Lithography Technology and Applications)
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17 pages, 2618 KiB  
Review
Nanochitosan: Commemorating the Metamorphosis of an ExoSkeletal Waste to a Versatile Nutraceutical
by Iyyakkannu Sivanesan, Manikandan Muthu, Judy Gopal, Nazim Hasan, Syed Kashif Ali, Juhyun Shin and Jae-Wook Oh
Nanomaterials 2021, 11(3), 821; https://doi.org/10.3390/nano11030821 - 23 Mar 2021
Cited by 20 | Viewed by 3520
Abstract
Chitin (poly-N-acetyl-D-glucosamine) is the second (after cellulose) most abundant organic polymer. In its deacetylated form—chitosan—becomes a very interesting material for medical use. The chitosan nano-structures whose preparation is described in this article shows unique biomedical value. The preparation of nanochitosan, as [...] Read more.
Chitin (poly-N-acetyl-D-glucosamine) is the second (after cellulose) most abundant organic polymer. In its deacetylated form—chitosan—becomes a very interesting material for medical use. The chitosan nano-structures whose preparation is described in this article shows unique biomedical value. The preparation of nanochitosan, as well as the most vital biomedical applications (antitumor, drug delivery and other medical uses), have been discussed in this review. The challenges confronting the progress of nanochitosan from benchtop to bedside clinical settings have been evaluated. The need for inclusion of nano aspects into chitosan research, with improvisation from nanotechnological inputs has been prescribed for breaking down the limitations. Future perspectives of nanochitosan and the challenges facing nanochitosan applications and the areas needing research focus have been highlighted. Full article
(This article belongs to the Special Issue Nanonutraceuticals Delivery)
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22 pages, 4842 KiB  
Article
Progress in Traceable Nanoscale Capacitance Measurements Using Scanning Microwave Microscopy
by François Piquemal, José Morán-Meza, Alexandra Delvallée, Damien Richert and Khaled Kaja
Nanomaterials 2021, 11(3), 820; https://doi.org/10.3390/nano11030820 - 23 Mar 2021
Cited by 6 | Viewed by 3414
Abstract
Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a [...] Read more.
Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a detailed investigation of most possible error sources that affect the uncertainty of capacitance measurements on the reference calibration samples. We establish a comprehensive uncertainty budget leading to a combined uncertainty of 3% in relative value (uncertainty given at one standard deviation) for capacitances ranging from 0.2 fF to 10 fF. This uncertainty level can be achieved even with the use of unshielded probes. We show that the weights of uncertainty sources vary with the values and dimensions of measured capacitances. Our work offers improvements on the classical calibration methods known in SMM and suggests possible new designs of reference standards for capacitance and dielectric traceable measurements. Experimental measurements are supported by numerical calculations of capacitances to reveal further paths for even higher improvements. Full article
(This article belongs to the Special Issue Nanometrology)
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11 pages, 2097 KiB  
Article
Thermoelectric Characteristics of A Single-Crystalline Topological Insulator Bi2Se3 Nanowire
by Dedi, Ping-Chung Lee, Pai-Chun Wei and Yang-Yuan Chen
Nanomaterials 2021, 11(3), 819; https://doi.org/10.3390/nano11030819 - 23 Mar 2021
Cited by 21 | Viewed by 3702
Abstract
The discovery of topological insulators (TIs) has motivated detailed studies on their physical properties, especially on their novel surface states via strong spin–orbit interactions. However, surface-state-related thermoelectric properties are rarely reported, likely because of the involvement of their bulk-dominating contribution. In this work, [...] Read more.
The discovery of topological insulators (TIs) has motivated detailed studies on their physical properties, especially on their novel surface states via strong spin–orbit interactions. However, surface-state-related thermoelectric properties are rarely reported, likely because of the involvement of their bulk-dominating contribution. In this work, we report thermoelectric studies on a TI bismuth selenide (Bi2Se3) nanowire (NW) that exhibit a larger surface/volume ratio. Uniform single-crystalline TI Bi2Se3 NWs were successfully synthesized using a stress-induced growth method. To achieve the study of the thermoelectric properties of a nanowire (NW), including electrical conductivity (σ), Seebeck coefficient (S), and thermal conductivity (κ), a special platform for simultaneously performing all measurements on a single wire was designed. The properties of σ, S, and κ of a 200 nm NW that was well precharacterized using transmission electron microscope (TEM) measurements were determined using the four-probe method, the two-probe EMF across ∇T measurement, and the 3ω technique, respectively. The integrated TE properties represented by the figure of merit ZT (S2σT/κ) were found to be in good agreement with a theoretical study of Bi2Se3 NW. Full article
(This article belongs to the Special Issue Transport Properties of Nanowires)
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12 pages, 2493 KiB  
Article
Chromogenic Chemodosimeter Based on Capped Silica Particles to Detect Spermine and Spermidine
by Mariana Barros, Alejandro López-Carrasco, Pedro Amorós, Salvador Gil, Pablo Gaviña, Margarita Parra, Jamal El Haskouri, Maria Carmen Terencio and Ana M. Costero
Nanomaterials 2021, 11(3), 818; https://doi.org/10.3390/nano11030818 - 23 Mar 2021
Cited by 3 | Viewed by 2733
Abstract
A new hybrid organic–inorganic material for sensing spermine (Spm) and spermidine (Spd) has been prepared and characterized. The material is based on MCM-41 particles functionalized with an N-hydroxysuccinimide derivative and loaded with Rhodamine 6G. The cargo is kept inside the porous material due [...] Read more.
A new hybrid organic–inorganic material for sensing spermine (Spm) and spermidine (Spd) has been prepared and characterized. The material is based on MCM-41 particles functionalized with an N-hydroxysuccinimide derivative and loaded with Rhodamine 6G. The cargo is kept inside the porous material due to the formation of a double layer of organic matter. The inner layer is covalently bound to the silica particles, while the external layer is formed through hydrogen and hydrophobic interactions. The limits of detection determined by fluorimetric titration are 27 µM and 45 µM for Spm and Spd, respectively. The sensor remains silent in the presence of other biologically important amines and is able to detect Spm and Spd in both aqueous solution and cells. Full article
(This article belongs to the Special Issue Frontiers in Functional Nanomaterials)
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20 pages, 3362 KiB  
Article
Biochemical, Ameliorative and Cytotoxic Effects of Newly Synthesized Curcumin Microemulsions: Evidence from In Vitro and In Vivo Studies
by Abbas Rahdar, Mohammad Reza Hajinezhad, Saman Sargazi, Maryam Zaboli, Mahmood Barani, Francesco Baino, Muhammad Bilal and Esmael Sanchooli
Nanomaterials 2021, 11(3), 817; https://doi.org/10.3390/nano11030817 - 23 Mar 2021
Cited by 34 | Viewed by 3447
Abstract
Curcumin is known to exhibit antioxidant and tissue-healing properties and has recently attracted the attention of the biomedical community for potential use in advanced therapies. This work reports the formulation and characterization of oil-in-water F127 microemulsions to enhance the bioavailability of curcumin Microemulsions [...] Read more.
Curcumin is known to exhibit antioxidant and tissue-healing properties and has recently attracted the attention of the biomedical community for potential use in advanced therapies. This work reports the formulation and characterization of oil-in-water F127 microemulsions to enhance the bioavailability of curcumin Microemulsions showed a high encapsulation efficiency and prolonged release. To investigate the interactions of curcumin with one unit of the polymeric chain of surfactant F127, ethyl butyrate, and sodium octanoate, as well as the interaction between ethyl butyrate and one unit of the F127 polymer chain, the Density Functional Theory (DFT) calculations at the M06-2X level of theory, were performed in water solution. The MTT assay was used to assess the cytotoxicity of free and encapsulated curcumin on non-malignant and malignant cell lines. Combination effects were calculated according to Chou-Talalay’s principles. Results of in vitro studies indicated that MCF7 and HepG2 cells were more sensitive to curcumin microemulsions. Moreover, a synergistic relationship was observed between curcumin microemulsions and cisplatin in all affected fractions of MCF7 and HepG2 cells (CI < 0.9). For in vivo investigation, thioacetamide-intoxicated rats received thioacetamide (100 mg/kg Sc) followed by curcumin microemulsions (30 mg/kg Ip). Thioacetamide-intoxicated rats showed elevated serum liver enzymes, blood urea nitrogen (BUN), and creatinine levels, and a significant reduction in liver superoxide dismutase (SOD) and catalase (CAT) activities (p < 0.05). Curcumin microemulsions reduced liver enzymes and serum creatinine and increased the activity of antioxidant enzymes in thioacetamide-treated rats in comparison to the untreated thioacetamide-intoxicated group. Histopathological investigations confirmed the biochemical findings. Overall, the current results showed the desirable hepatoprotective, nephroprotective, and anti-cancer effects of curcumin microemulsions. Full article
(This article belongs to the Special Issue Advances in Nanoecotoxicology: From the Molecular to the Biological Level and Back)
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10 pages, 2239 KiB  
Article
Advanced Optical Detection through the Use of a Deformably Transferred Nanofilm
by Kossi Aniya Amedome Min-Dianey, Top Khac Le, Jeong Ryeol Choi and Phuong V. Pham
Nanomaterials 2021, 11(3), 816; https://doi.org/10.3390/nano11030816 - 23 Mar 2021
Cited by 11 | Viewed by 2568
Abstract
Graphene has been extensively investigated in advanced photodetection devices for its broadband absorption, high carrier mobility, and mechanical flexibility. Due to graphene’s low optical absorptivity (2.3%), graphene-based photodetection research so far has focused on hybrid systems to increase photoabsorption. However, such hybrid systems [...] Read more.
Graphene has been extensively investigated in advanced photodetection devices for its broadband absorption, high carrier mobility, and mechanical flexibility. Due to graphene’s low optical absorptivity (2.3%), graphene-based photodetection research so far has focused on hybrid systems to increase photoabsorption. However, such hybrid systems require a complicated integration process and lead to reduced carrier mobility due to heterogeneous interfaces. Crumpled or deformed graphene has previously been reported in electronics and optoelectronics. However, a depth study on the influence of the morphology of nanofilms (e.g., graphite or graphene) related to light absorption in photodetection devices has not been demonstrated yet. Here, we present an interesting study in terms of the effect of the deformable surface and the smooth surface of a nanofilm transferred onto Si through two transfer strategies using isopropanol injection and nitrogen blowing (to form a deformable nanofilm surface) and deionized water injection and van der Waals interaction (to form a smooth nanofilm surface). As a result, optical detection in the case of the deformable nanofilm surface was enhanced significantly (~100%) compared with that of the smooth nanofilm surface in the visible laser wavelength (532 nm). In addition, evidence from the computational simulation also firmly affirms an advancement in the optical detection of deformed nanofilm-surface-based photodetection devices compatible with the experimental results. Full article
(This article belongs to the Special Issue Functional Nanomaterials for Material Characterization and Chemical Analysis)
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15 pages, 2638 KiB  
Article
Nanoemulsions for Enhancement of Curcumin Bioavailability and Their Safety Evaluation: Effect of Emulsifier Type
by Raquel F. S. Gonçalves, Joana T. Martins, Luís Abrunhosa, António A. Vicente and Ana C. Pinheiro
Nanomaterials 2021, 11(3), 815; https://doi.org/10.3390/nano11030815 - 23 Mar 2021
Cited by 27 | Viewed by 3454
Abstract
This work aimed at evaluating the effects of different emulsifiers on curcumin-loaded nanoemulsions’ behavior during digestion, its safety and absorption, to develop nanoemulsions that provide safety and improved curcumin functionality. Nanoemulsions (NEs) were produced using two bio-based (lecithin (LEC) and rhamnolipids (RHAM)) and [...] Read more.
This work aimed at evaluating the effects of different emulsifiers on curcumin-loaded nanoemulsions’ behavior during digestion, its safety and absorption, to develop nanoemulsions that provide safety and improved curcumin functionality. Nanoemulsions (NEs) were produced using two bio-based (lecithin (LEC) and rhamnolipids (RHAM)) and one synthetic (Tween®80 (TWE)) emulsifier at similar concentrations. Different NEs were subjected to in vitro digestion. The cytotoxicity and permeability tests were performed in Caco-2 cells. NE_TWE were stable during all phases of in vitro digestion, whereas NE_LEC and NE_RHAM were found to be unstable from the gastric phase. NE_TWE showed 100% of free fatty acids released, followed by NE_RHAM and NE_LEC. Curcumin’s bioaccessibility and stability increased in the following order: NE_LEC > NE_RHAM > NE_TWE. NE_LEC and NE_TWE did not show cytotoxic effects in any of the concentrations tested, while NE_RHAM presented high cytotoxicity in all concentrations tested. The apparent permeability coefficients were determined for NE_LEC and NE_TWE; however, the results were not statistically different. These results showed that the emulsifier used has a high impact on nanoemulsions’ behavior under the digestion process and on their cytotoxicity. This work contributed to the state-of-the-art’s progress on the development of safer curcumin delivery systems with improved functionality, particularly regarding the proper selection of ingredients to produce said systems. Full article
(This article belongs to the Special Issue Advances in Food Nanotechnology)
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11 pages, 9894 KiB  
Article
Synthesis of Air-Stable Cu Nanoparticles Using Laser Reduction in Liquid
by Ashish Nag, Laysa Mariela Frias Batista and Katharine Moore Tibbetts
Nanomaterials 2021, 11(3), 814; https://doi.org/10.3390/nano11030814 - 23 Mar 2021
Cited by 18 | Viewed by 4292
Abstract
We report the synthesis of air-stable Cu nanoparticles (NPs) using the bottom-up laser reduction in liquid method. Precursor solutions of copper acetlyacetonate in a mixture of methanol and isopropyl alcohol were irradiated with femtosecond laser pulses to produce Cu NPs. The Cu NPs [...] Read more.
We report the synthesis of air-stable Cu nanoparticles (NPs) using the bottom-up laser reduction in liquid method. Precursor solutions of copper acetlyacetonate in a mixture of methanol and isopropyl alcohol were irradiated with femtosecond laser pulses to produce Cu NPs. The Cu NPs were left at ambient conditions and analyzed at different ages up to seven days. TEM analysis indicates a broad size distribution of spherical NPs surrounded by a carbon matrix, with the majority of the NPs less than 10 nm and small numbers of large particles up to ∼100 nm in diameter. XRD collected over seven days confirmed the presence of fcc-Cu NPs, with some amorphous Cu2O, indicating the stability of the zero-valent Cu phase. Raman, FTIR, and XPS data for oxygen and carbon regions put together indicated the presence of a graphite oxide-like carbon matrix with oxygen functional groups that developed within the first 24 h after synthesis. The Cu NPs were highly active towards the model catalytic reaction of para-nitrophenol reduction in the presence of NaBH4. Full article
(This article belongs to the Special Issue Laser Synthesis of Nanomaterials)
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19 pages, 4408 KiB  
Review
Liquid Crystal Elastomers for Biological Applications
by Mariam Hussain, Ethan I. L. Jull, Richard J. Mandle, Thomas Raistrick, Peter J. Hine and Helen F. Gleeson
Nanomaterials 2021, 11(3), 813; https://doi.org/10.3390/nano11030813 - 22 Mar 2021
Cited by 48 | Viewed by 7521
Abstract
The term liquid crystal elastomer (LCE) describes a class of materials that combine the elastic entropy behaviour associated with conventional elastomers with the stimuli responsive properties of anisotropic liquid crystals. LCEs consequently exhibit attributes of both elastomers and liquid crystals, but additionally have [...] Read more.
The term liquid crystal elastomer (LCE) describes a class of materials that combine the elastic entropy behaviour associated with conventional elastomers with the stimuli responsive properties of anisotropic liquid crystals. LCEs consequently exhibit attributes of both elastomers and liquid crystals, but additionally have unique properties not found in either. Recent developments in LCE synthesis, as well as the understanding of the behaviour of liquid crystal elastomers—namely their mechanical, optical and responsive properties—is of significant relevance to biology and biomedicine. LCEs are abundant in nature, highlighting the potential use of LCEs in biomimetics. Their exceptional tensile properties and biocompatibility have led to research exploring their applications in artificial tissue, biological sensors and cell scaffolds by exploiting their actuation and shock absorption properties. There has also been significant recent interest in using LCEs as a model for morphogenesis. This review provides an overview of some aspects of LCEs which are of relevance in different branches of biology and biomedicine, as well as discussing how recent LCE advances could impact future applications. Full article
(This article belongs to the Special Issue Bionanotechnology and Nanobiotechnology: Biomimetics or Engineering Nature?)
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23 pages, 5222 KiB  
Article
Evaluation of Local Mechanical and Chemical Properties via AFM as a Tool for Understanding the Formation Mechanism of Pulsed UV Laser-Nanoinduced Patterns on Azo-Naphthalene-Based Polyimide Films
by Iuliana Stoica, Elena-Luiza Epure, Catalin-Paul Constantin, Mariana-Dana Damaceanu, Elena-Laura Ursu, Ilarion Mihaila and Ion Sava
Nanomaterials 2021, 11(3), 812; https://doi.org/10.3390/nano11030812 - 22 Mar 2021
Cited by 19 | Viewed by 3153
Abstract
Aromatic polyimides containing side azo-naphthalene groups have been investigated regarding their capacity of generating surface relief gratings (SRGs) under pulsed UV laser irradiation through phase masks, using different fluencies and pulse numbers. The process of the material photo-fluidization and the supramolecular re-organization of [...] Read more.
Aromatic polyimides containing side azo-naphthalene groups have been investigated regarding their capacity of generating surface relief gratings (SRGs) under pulsed UV laser irradiation through phase masks, using different fluencies and pulse numbers. The process of the material photo-fluidization and the supramolecular re-organization of the surface were investigated using atomic force microscopy (AFM). At first, an AFM nanoscale topographical analysis of the induced SRGs was performed in terms of morphology and tridimensional amplitude, spatial, hybrid, and functional parameters. Afterward, a nanomechanical characterization of SRGs using an advanced method, namely, AFM PinPoint mode, was performed, where the quantitative nanomechanical properties (i.e., modulus, adhesion, deformation) of the nanostructured azo-polyimide surfaces were acquired with a highly correlated topographic registration. This method proved to be very effective in understanding the formation mechanism of the surface modulations during pulsed UV laser irradiation. Additionally to AFM investigations, confocal Raman measurements and molecular simulations were performed to provide information about structured azo-polyimide chemical composition and macromolecular conformation induced by laser irradiation. Full article
(This article belongs to the Special Issue Tuning the Physicochemical Properties of Nanostructured Materials through Advanced Preparation Methods)
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21 pages, 30687 KiB  
Article
Mesoporous Iron(III)-Doped Hydroxyapatite Nanopowders Obtained via Iron Oxalate
by Margarita A. Goldberg, Marat R. Gafurov, Fadis F. Murzakhanov, Alexander S. Fomin, Olga S. Antonova, Dinara R. Khairutdinova, Andrew V. Pyataev, Olga N. Makshakova, Anatoliy A. Konovalov, Alexander V. Leonov, Suraya A. Akhmedova, Irina K. Sviridova, Natalia S. Sergeeva, Sergey M. Barinov and Vladimir S. Komlev
Nanomaterials 2021, 11(3), 811; https://doi.org/10.3390/nano11030811 - 22 Mar 2021
Cited by 26 | Viewed by 4213
Abstract
Mesoporous hydroxyapatite (HA) and iron(III)-doped HA (Fe-HA) are attractive materials for biomedical, catalytic, and environmental applications. In the present study, the nanopowders of HA and Fe-HA with a specific surface area up to 194.5 m2/g were synthesized by a simple precipitation [...] Read more.
Mesoporous hydroxyapatite (HA) and iron(III)-doped HA (Fe-HA) are attractive materials for biomedical, catalytic, and environmental applications. In the present study, the nanopowders of HA and Fe-HA with a specific surface area up to 194.5 m2/g were synthesized by a simple precipitation route using iron oxalate as a source of Fe3+ cations. The influence of Fe3+ amount on the phase composition, powders morphology, Brunauer–Emmett–Teller (BET) specific surface area (S), and pore size distribution were investigated, as well as electron paramagnetic resonance and Mössbauer spectroscopy analysis were performed. According to obtained data, the Fe3+ ions were incorporated in the HA lattice, and also amorphous Fe oxides were formed contributed to the gradual increase in the S and pore volume of the powders. The Density Functional Theory calculations supported these findings and revealed Fe3+ inclusion in the crystalline region with the hybridization among Fe-3d and O-2p orbitals and a partly covalent bond formation, whilst the inclusion of Fe oxides assumed crystallinity damage and rather occurred in amorphous regions of HA nanomaterial. In vitro tests based on the MG-63 cell line demonstrated that the introduction of Fe3+ does not cause cytotoxicity and led to the enhanced cytocompatibility of HA. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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29 pages, 6585 KiB  
Review
An Overview on Anodes for Magnesium Batteries: Challenges towards a Promising Storage Solution for Renewables
by Federico Bella, Stefano De Luca, Lucia Fagiolari, Daniele Versaci, Julia Amici, Carlotta Francia and Silvia Bodoardo
Nanomaterials 2021, 11(3), 810; https://doi.org/10.3390/nano11030810 - 22 Mar 2021
Cited by 101 | Viewed by 9057
Abstract
Magnesium-based batteries represent one of the successfully emerging electrochemical energy storage chemistries, mainly due to the high theoretical volumetric capacity of metallic magnesium (i.e., 3833 mAh cm−3 vs. 2046 mAh cm−3 for lithium), its low reduction potential (−2.37 V vs. SHE), [...] Read more.
Magnesium-based batteries represent one of the successfully emerging electrochemical energy storage chemistries, mainly due to the high theoretical volumetric capacity of metallic magnesium (i.e., 3833 mAh cm−3 vs. 2046 mAh cm−3 for lithium), its low reduction potential (−2.37 V vs. SHE), abundance in the Earth’s crust (104 times higher than that of lithium) and dendrite-free behaviour when used as an anode during cycling. However, Mg deposition and dissolution processes in polar organic electrolytes lead to the formation of a passivation film bearing an insulating effect towards Mg2+ ions. Several strategies to overcome this drawback have been recently proposed, keeping as a main goal that of reducing the formation of such passivation layers and improving the magnesium-related kinetics. This manuscript offers a literature analysis on this topic, starting with a rapid overview on magnesium batteries as a feasible strategy for storing electricity coming from renewables, and then addressing the most relevant outcomes in the field of anodic materials (i.e., metallic magnesium, bismuth-, titanium- and tin-based electrodes, biphasic alloys, nanostructured metal oxides, boron clusters, graphene-based electrodes, etc.). Full article
(This article belongs to the Special Issue Advances in Nanomaterials for Lithium-Ion/Post-Lithium-Ion Batteries and Supercapacitors)
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10 pages, 2851 KiB  
Article
Elongated-Hexagonal Photonic Crystal for Buffering, Sensing, and Modulation
by Sayed Elshahat, Israa Abood, Zixian Liang, Jihong Pei and Zhengbiao Ouyang
Nanomaterials 2021, 11(3), 809; https://doi.org/10.3390/nano11030809 - 22 Mar 2021
Cited by 6 | Viewed by 2045
Abstract
A paradigm for high buffering performance with an essential fulfillment for sensing and modulation was set forth. Through substituting the fundamental two rows of air holes in an elongated hexagonal photonic crystal (E-PhC) by one row of the triangular gaps, the EPCW is [...] Read more.
A paradigm for high buffering performance with an essential fulfillment for sensing and modulation was set forth. Through substituting the fundamental two rows of air holes in an elongated hexagonal photonic crystal (E-PhC) by one row of the triangular gaps, the EPCW is molded to form an irregular waveguide. By properly adjusting the triangle dimension solitary, we fulfilled the lowest favorable value of the physical-size of each stored bit by about μ5.5510 μm. Besides, the EPCW is highly sensitive to refractive index (RI) perturbation attributed to the medium through infiltrating the triangular gaps inside the EPCW by microfluid with high RI sensitivity of about 379.87 nm/RIU. Furthermore, dynamic modulation can be achieved by applying external voltage and high electro-optical (EO) sensitivity is obtained of about 748.407 nm/RIU. The higher sensitivity is attributable to strong optical confinement in the waveguide region and enhanced light-matter interaction in the region of the microfluid triangular gaps inside the EPCW and conventional gaps (air holes). The EPCW structure enhances the interaction between the light and the sensing medium. Full article
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14 pages, 2969 KiB  
Article
Synthesis of Gold Nanoparticles by Using Green Machinery: Characterization and In Vitro Toxicity
by Ahmed Al Saqr, El-Sayed Khafagy, Ahmed Alalaiwe, Mohammed F. Aldawsari, Saad M. Alshahrani, Md. Khalid Anwer, Salman Khan, Amr S. Abu Lila, Hany H. Arab and Wael A. H. Hegazy
Nanomaterials 2021, 11(3), 808; https://doi.org/10.3390/nano11030808 - 22 Mar 2021
Cited by 91 | Viewed by 5520
Abstract
Green synthesis of gold nanoparticles (GNPs) with plant extracts has gained considerable interest in the field of biomedicine. Recently, the bioreduction nature of herbal extracts has helped to synthesize spherical GNPs of different potential from gold salt. In this study, a fast ecofriendly [...] Read more.
Green synthesis of gold nanoparticles (GNPs) with plant extracts has gained considerable interest in the field of biomedicine. Recently, the bioreduction nature of herbal extracts has helped to synthesize spherical GNPs of different potential from gold salt. In this study, a fast ecofriendly method was adopted for the synthesis of GNPs using fresh peel (aqueous) extracts of Benincasa hispida, which acted as reducing and stabilizing agents. The biosynthesized GNPs were characterized by UV–VIS and Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering. In addition, the in vitro antibacterial and anticancer activities of synthesized GNPs were investigated. The formation of gold nanoparticles was confirmed by the existence of a sharp absorption peak at 520 nm, corresponding to the surface plasmon resonance (SPR) band of the GNPs. TEM analysis revealed that the prepared GNPs were spherical in shape and had an average particle size of 22.18 ± 2 nm. Most importantly, the synthesized GNPs exhibited considerable antibacterial activity against different Gram-positive and Gram-negative bacteria. Furthermore, the biosynthesized GNPs exerted remarkable in vitro cytotoxicity against human cervical cancer cell line, while sparing normal human primary osteoblast cells. Such cytotoxic effect was attributed to the increased production of reactive oxygen species (ROS) that contributed to the damage of HeLa cells. Collectively, peel extracts of B. hispida can be efficiently used for the synthesis of GNPs, which can be adopted as a natural source of antimicrobial and anticancer agent. Full article
(This article belongs to the Special Issue Advances in Antimicrobial Nanoparticles)
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9 pages, 3015 KiB  
Article
A High-Throughput NanoBiT-Based Serological Assay Detects SARS-CoV-2 Seroconversion
by Taha Azad, Reza Rezaei, Ragunath Singaravelu, Taylor R. Jamieson, Mathieu J. F. Crupi, Abera Surendran, Joanna Poutou, Parisa Taklifi, Juthaporn Cowan, Donald William Cameron and Carolina S. Ilkow
Nanomaterials 2021, 11(3), 807; https://doi.org/10.3390/nano11030807 - 22 Mar 2021
Cited by 9 | Viewed by 5156
Abstract
High-throughput detection strategies for antibodies against SARS-CoV-2 in patients recovering from COVID-19, or in vaccinated individuals, are urgently required during this ongoing pandemic. Serological assays are the most widely used method to measure antibody responses in patients. However, most of the current methods [...] Read more.
High-throughput detection strategies for antibodies against SARS-CoV-2 in patients recovering from COVID-19, or in vaccinated individuals, are urgently required during this ongoing pandemic. Serological assays are the most widely used method to measure antibody responses in patients. However, most of the current methods lack the speed, stability, sensitivity, and specificity to be selected as a test for worldwide serosurveys. Here, we demonstrate a novel NanoBiT-based serological assay for fast and sensitive detection of SARS-CoV-2 RBD-specific antibodies in sera of COVID-19 patients. This assay can be done in high-throughput manner at 384 samples per hour and only requires a minimum of 5 μL of serum or 10 ng of antibody. The stability of our NanoBiT reporter in various temperatures (4–42 °C) and pH (4–12) settings suggests the assay will be able to withstand imperfect shipping and handling conditions for worldwide seroepidemiologic surveillance in the post-vaccination period of the pandemic. Our newly developed rapid assay is highly accessible and may facilitate a more cost-effective solution for seroconversion screening as vaccination efforts progress. Full article
(This article belongs to the Section Biology and Medicines)
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11 pages, 1948 KiB  
Communication
Combined Toxicity of Gas Plasma Treatment and Nanoparticles Exposure in Melanoma Cells In Vitro
by Sander Bekeschus
Nanomaterials 2021, 11(3), 806; https://doi.org/10.3390/nano11030806 - 22 Mar 2021
Cited by 11 | Viewed by 2883
Abstract
Despite continuous advances in therapy, cancer remains a deadly disease. Over the past years, gas plasma technology emerged as a novel tool to target tumors, especially skin. Another promising anticancer approach are nanoparticles. Since combination therapies are becoming increasingly relevant in oncology, both [...] Read more.
Despite continuous advances in therapy, cancer remains a deadly disease. Over the past years, gas plasma technology emerged as a novel tool to target tumors, especially skin. Another promising anticancer approach are nanoparticles. Since combination therapies are becoming increasingly relevant in oncology, both gas plasma treatment and nanoparticle exposure were combined. A series of nanoparticles were investigated in parallel, namely, silica, silver, iron oxide, cerium oxide, titanium oxide, and iron-doped titanium oxide. For gas plasma treatment, the atmospheric pressure argon plasma jet kINPen was utilized. Using three melanoma cell lines, the two murine non-metastatic B16F0 and metastatic B16F10 cells and the human metastatic B-Raf mutant cell line SK-MEL-28, the combined cytotoxicity of both approaches was identified. The combined cytotoxicity of gas plasma treatment and nanoparticle exposure was consistent across all three cell lines for silica, silver, iron oxide, and cerium oxide. In contrast, for titanium oxide and iron-doped titanium oxide, significantly combined cytotoxicity was only observed in B16F10 cells. Full article
(This article belongs to the Special Issue Combination of Cold Atmospheric Plasma and Nanomaterials in Cancer Treatment)
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15 pages, 4017 KiB  
Article
Evaluation of Fe-Mg Binary Oxide for As (III) Adsorption—Synthesis, Characterization and Kinetic Modelling
by Saif Ullah Khan, Rumman Zaidi, Feroz Shaik, Izharul Haq Farooqi, Ameer Azam, Hatem Abuhimd and Faheem Ahmed
Nanomaterials 2021, 11(3), 805; https://doi.org/10.3390/nano11030805 - 21 Mar 2021
Cited by 16 | Viewed by 2743
Abstract
Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO3·9H2O and MgNO [...] Read more.
Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO3·9H2O and MgNO3·6H2O in a proportion of molar concentration 1:1 and was later evaluated in removing As (III) from contaminated waters. Characterization of the prepared nanomaterial was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX) and ultraviolet–visible spectrophotometry (UV-VIS). Experimental studies on batch scale were carried out, examining the effect of varying initial concentrations of metal, adsorbent dosage, application time and initial pH on removal efficiency. Arsenic removal increased on increasing adsorbent dosage (0.1–1 g/L) but trend reversed on increasing initial arsenic concentration attaining qmax of 263.20 mg/g. Adsorption was quite efficient in pH range 4–8. Freundlich fitted better for adsorption isotherm along with following Pseudo-2nd order kinetics. The reusability and effect of co-existing ions on arsenic adsorption, namely SO42−, CO32− and PO43− were also explored with reusability in 1st and 2nd cycles attained adsorptive removal up to 77% and 64% respectively. The prepared nano-adsorbent showed promising results in terms of high arsenic uptake (qmax of 263.20 mg/g) along with facile and cost-effective synthesis. Thus, the co-precipitation technique used in this work is a simple one step procedure without any use of any precursor as compared to most of the other procedures used for synthesis. Full article
(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)
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13 pages, 5920 KiB  
Article
Formation of Nickel Oxide Nanocuboids in Ferromagnetic La2Ni1−xMn1+xO6
by Monica Bernal-Salamanca, Zorica Konstantinović, Carlos Frontera, Víctor Fuentes, Alberto Pomar, Lluis Balcells and Benjamín Martínez
Nanomaterials 2021, 11(3), 804; https://doi.org/10.3390/nano11030804 - 21 Mar 2021
Cited by 1 | Viewed by 2210
Abstract
The control of the spontaneous formation of nanostructures at the surface of thin films is of strong interest in many different fields, from catalysts to microelectronics, because surface and interfacial properties may be substantially enhanced. Here, we analyze the formation of nickel oxide [...] Read more.
The control of the spontaneous formation of nanostructures at the surface of thin films is of strong interest in many different fields, from catalysts to microelectronics, because surface and interfacial properties may be substantially enhanced. Here, we analyze the formation of nickel oxide nanocuboids on top of La2Ni1−xMn1+xO6 double perovskite ferromagnetic thin films, epitaxially grown on SrTiO3 (001) substrates by radio-frequency (RF) magnetron sputtering. We show that, by annealing the films at high temperature under high oxygen partial pressure, the spontaneous segregation of nanocuboids is enhanced. The evolution of the structural and magnetic properties of the films is studied as a function of the annealing treatments at different temperatures. It is shown that the formation of NiOx nanocuboids leads to a nanostructured film surface with regions of locally different electrical transport characteristics. Full article
(This article belongs to the Special Issue Magnetic and Magnetoelectric Nanomaterials: Synthesis, Characterization and Applications)
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12 pages, 2772 KiB  
Article
Protective Effect of Lactobacillus rhamnosus GG on TiO2 Nanoparticles-Induced Oxidative Stress Damage in the Liver of Young Rats
by Penghui Nie, Mengqi Wang, Yu Zhao, Shanji Liu, Ling Chen and Hengyi Xu
Nanomaterials 2021, 11(3), 803; https://doi.org/10.3390/nano11030803 - 21 Mar 2021
Cited by 18 | Viewed by 2825
Abstract
The potential toxicity of titanium dioxide nanoparticles (TiO2 NPs) to mammals has become a widespread concern. Young individuals exposed to TiO2 NPs have a higher risk than adults. In this study, the protective effects of Lactobacillus rhamnosus GG (LGG) on liver [...] Read more.
The potential toxicity of titanium dioxide nanoparticles (TiO2 NPs) to mammals has become a widespread concern. Young individuals exposed to TiO2 NPs have a higher risk than adults. In this study, the protective effects of Lactobacillus rhamnosus GG (LGG) on liver toxicity in young rats induced by TiO2 NPs were explored. Results show that the four-week-old rats that underwent LGG after the oral intake of TiO2 NPs could prevent weight loss, reduce hematological indicators (WBC and NEUT) and serum biochemical indicators (AST, ALT, AST/ALT, and ALP). Moreover, it alleviated the pathological damage of the liver (as indicated by the disordered hepatocytes, more eosinophilic, ballooning degeneration, and accompany with blood cells), but it did not reduce the Ti contents in the liver. In addition, RT-qPCR results indicated that LGG restored the expression of anti-oxidative stress-related genes, such as SOD1, SOD2, CAT, HO-1, GSH, GCLC, and GCLM in the liver. In summary, the hepatotoxicity of TiO2 NPs in young rats is closely related to oxidative stress, and the antioxidant effect of LGG might protect the harmful effects caused by TiO2 NPs. Full article
(This article belongs to the Special Issue Cytotoxicity and Genotoxicity of Nanomaterials)
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16 pages, 3799 KiB  
Article
Assessing the Carboxymethylcellulose Copper-Montmorillonite Nanocomposite for Controlling the Infection of Erwinia carotovora in Potato (Solanum tuberosum L.)
by Ryan Rienzie, Lasantha Sendanayake, Devika De Costa, Akbar Hossain, Marian Brestic, Milan Skalicky, Pavla Vachova and Nadeesh M. Adassooriya
Nanomaterials 2021, 11(3), 802; https://doi.org/10.3390/nano11030802 - 21 Mar 2021
Cited by 7 | Viewed by 2851
Abstract
A novel antimicrobial formulation based on carboxymethylcellulose (CMC) spray-coated Cu2+ intercalated montmorillonite (MMT) nanocomposite material was prepared and its morphology, internal structure, and bonding interactions were studied. Meanwhile, the antibacterial efficacy and release behavior of Cu2+ was also determined. PXRD patterns [...] Read more.
A novel antimicrobial formulation based on carboxymethylcellulose (CMC) spray-coated Cu2+ intercalated montmorillonite (MMT) nanocomposite material was prepared and its morphology, internal structure, and bonding interactions were studied. Meanwhile, the antibacterial efficacy and release behavior of Cu2+ was also determined. PXRD patterns indicated the intercalation of Cu2+, while FTIR spectra and TGA traces confirmed the association of Cu−MMT with CMC. SEM study revealed the improvement of nanocomposites by CMC, without disturbing the clay structure. TEM and EDAX studies indicated the distribution of Cu (copper) throughout the composite. In vitro antibacterial assays performed with Erwinia carotovora revealed effective bacterial growth suppression, indicating the potential of this material in controlling soft rot of potatoes (Solanum tuberosum); also observed was a connection between growth inhibition and concentration of CMC spray coats indicating a positive relationship between Cu2+ release and concentration of the CMC coatings. The activity pattern of the nanocomposite displayed a significant degree of sustained-release behavior. Full article
(This article belongs to the Special Issue Influence of Nanoparticles on Plants: The Pros and Cons)
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21 pages, 6956 KiB  
Review
A Review of Smart Lubricant-Infused Surfaces for Droplet Manipulation
by Zhentao Hao and Weihua Li
Nanomaterials 2021, 11(3), 801; https://doi.org/10.3390/nano11030801 - 21 Mar 2021
Cited by 18 | Viewed by 4373
Abstract
The nepenthes-inspired lubricant-infused surface (LIS) is emerging as a novel repellent surface with self-healing, self-cleaning, pressure stability and ultra-slippery properties. Recently, stimuli-responsive materials to construct a smart LIS have broadened the application of LIS for droplet manipulation, showing great promise in microfluidics. This [...] Read more.
The nepenthes-inspired lubricant-infused surface (LIS) is emerging as a novel repellent surface with self-healing, self-cleaning, pressure stability and ultra-slippery properties. Recently, stimuli-responsive materials to construct a smart LIS have broadened the application of LIS for droplet manipulation, showing great promise in microfluidics. This review mainly focuses on the recent developments towards the droplet manipulation on LIS with different mechanisms induced by various external stimuli, including thermo, light, electric, magnetism, and mechanical force. First, the droplet condition on LIS, determined by the properties of the droplet, the lubricant and substrate, is illustrated. Droplet manipulation via altering the droplet regime realized by different mechanisms, such as varying slipperiness, electrostatic force and wettability, is discussed. Moreover, some applications on droplet manipulation employed in various filed, including microreactors, microfluidics, etc., are also presented. Finally, a summary of this work and possible future research directions for the transport of droplets on smart LIS are outlined to promote the development of this field. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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9 pages, 2451 KiB  
Article
Asymmetric Hysteresis Loops in Structured Ferromagnetic Nanoparticles with Hard/Soft Areas
by Joscha Detzmeier, Kevin Königer, Tomasz Blachowicz and Andrea Ehrmann
Nanomaterials 2021, 11(3), 800; https://doi.org/10.3390/nano11030800 - 21 Mar 2021
Cited by 10 | Viewed by 3743
Abstract
Horizontally shifted and asymmetric hysteresis loops are often associated with exchange-biased samples, consisting of a ferromagnet exchange coupled with an antiferromagnet. In purely ferromagnetic samples, such effects can occur due to undetected minor loops or thermal effects. Simulations of ferromagnetic nanostructures at zero [...] Read more.
Horizontally shifted and asymmetric hysteresis loops are often associated with exchange-biased samples, consisting of a ferromagnet exchange coupled with an antiferromagnet. In purely ferromagnetic samples, such effects can occur due to undetected minor loops or thermal effects. Simulations of ferromagnetic nanostructures at zero temperature with sufficiently large saturation fields should not lead to such asymmetries. Here we report on micromagnetic simulations at zero temperature, performed on sputtered nanoparticles with different structures. The small deviations of the systems due to random anisotropy orientations in the different grains can not only result in strong deviations of magnetization reversal processes and hysteresis loops, but also lead to distinctly asymmetric, horizontally shifted hysteresis loops in purely ferromagnetic nanoparticles. Full article
(This article belongs to the Special Issue Selected Papers from the 2nd International Online Conference on Nanomaterials)
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12 pages, 4498 KiB  
Article
Preparation of Carbon-Covered Phosphorus-Modified Alumina with Large Pore Size and Adsorption of Rhodamine B
by Shuaiqi Chen, Xuhui Wang, Weiyi Tong, Jianchuan Sun, Xiangyu Xu, Jiaqing Song, Jianyi Gong and Wei Chen
Nanomaterials 2021, 11(3), 799; https://doi.org/10.3390/nano11030799 - 20 Mar 2021
Cited by 4 | Viewed by 2539
Abstract
In this study, phosphorus-modified alumina with large pore size was synthesized through a coprecipitation method. The carbon-covered, phosphorus-modified alumina with large pores was prepared by impregnating with glucose and carbonizing to further improve the adsorption of organic dyes. The morphology and structure of [...] Read more.
In this study, phosphorus-modified alumina with large pore size was synthesized through a coprecipitation method. The carbon-covered, phosphorus-modified alumina with large pores was prepared by impregnating with glucose and carbonizing to further improve the adsorption of organic dyes. The morphology and structure of these composites were characterized by various analysis methods, and Rhodamine B (RhB) adsorption was also examined in aqueous media. The results showed that the specific surface area and pore size of the phosphorus-modified alumina sample AP7 (prepared with a P/Al molar ratio of 0.07) reached 496.2 m2·g−1 and 21.9 nm, while the specific surface area and pore size of the carbon-covered phosphorus-modified alumina sample CAP7–27 (prepared by using AP7 as a carrier for glucose at a glucose/Al molar ratio of 0.27) reached 435.3 m2·g−1 and 21.2 nm. The adsorption experiment of RhB revealed that CAP7–27 had not only an equilibrium adsorption capacity of 198 mg·g−1, but also an adsorption rate of 162.5 mg·g−1 in 5 min. These superior adsorption effects can be attributed to the similar pore structures of CAP7–27 with those of alumina and the specific properties with those of carbon materials. Finally, the kinetic properties of these composites were also studied, which were found to be consistent with a pseudo-second-order kinetic model and Langmuir model for isothermal adsorption analysis. This study indicates that the prepared nanomaterials are expected to be promising candidates for efficient adsorption of toxic dyes. Full article
(This article belongs to the Special Issue Nanostructured Materials for Adsorption)
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19 pages, 5154 KiB  
Article
New Sustainable, Scalable and One-Step Synthesis of Iron Oxide Nanoparticles by Ion Exchange Process
by Ludovico Macera, Valeria Daniele, Claudia Mondelli, Marie Capron and Giuliana Taglieri
Nanomaterials 2021, 11(3), 798; https://doi.org/10.3390/nano11030798 - 20 Mar 2021
Cited by 10 | Viewed by 4563
Abstract
This work introduces an innovative, sustainable, and scalable synthesis of iron oxides nanoparticles (NPs) in aqueous suspension. The method, based on ion exchange process, consists of a one-step procedure, time and energy saving, operating in water and at room temperature, by cheap and [...] Read more.
This work introduces an innovative, sustainable, and scalable synthesis of iron oxides nanoparticles (NPs) in aqueous suspension. The method, based on ion exchange process, consists of a one-step procedure, time and energy saving, operating in water and at room temperature, by cheap and renewable reagents. The influence of both oxidation state of the initial reagent and reaction atmosphere is considered. Three kinds of iron nanostructured compounds are obtained (2-lines ferrihydrite; layered-structure iron oxyhydroxide δ-FeOOH; and cubic magnetite), in turn used as precursors to obtain hematite and maghemite NPs. All the produced NPs are characterized by a high purity, small particles dimensions (from 2 to 50 nm), and high specific surface area values up to 420 m2/g, with yields of production >90%. In particular, among the most common iron oxide NPs, we obtained cubic magnetite NPs at room temperature, characterized by particle dimensions of about 6 nm and a surface area of 170 m2/g. We also obtained hematite NPs at very low temperature conditions (that is 2 h at 200 °C), characterized by particles dimensions of about 5 nm with a surface area value of 200 m2/g. The obtained results underline the strength of the synthetic method to provide a new, sustainable, tunable, and scalable high-quality production. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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11 pages, 2363 KiB  
Article
Thermal Traits of MNPs under High-Frequency Magnetic Fields: Disentangling the Effect of Size and Coating
by David Aurélio, Jiří Mikšátko, Miroslav Veverka, Magdalena Michlová, Martin Kalbáč and Jana Vejpravová
Nanomaterials 2021, 11(3), 797; https://doi.org/10.3390/nano11030797 - 19 Mar 2021
Cited by 3 | Viewed by 2503
Abstract
We investigated the heating abilities of magnetic nanoparticles (MNPs) in a high-frequency magnetic field (MF) as a function of surface coating and size. The cobalt ferrite MNPs were obtained by a hydrothermal method in a water–oleic acid–ethanol system, yielding MNPs with mean diameter [...] Read more.
We investigated the heating abilities of magnetic nanoparticles (MNPs) in a high-frequency magnetic field (MF) as a function of surface coating and size. The cobalt ferrite MNPs were obtained by a hydrothermal method in a water–oleic acid–ethanol system, yielding MNPs with mean diameter of about 5 nm, functionalized with the oleic acid. By applying another cycle of hydrothermal synthesis, we obtained MNPs with about one nm larger diameter. In the next step, the oleic acid was exchanged for 11-maleimidoundecanoic acid or 11-(furfurylureido)undecanoic acid. For the heating experiments, all samples were dispersed in the same solvent (dichloroethane) in the same concentration and the heating performance was studied in a broad interval of MF frequencies (346–782 kHz). The obtained results enabled us to disentangle the impact of the hydrodynamic, structural, and magnetic parameters on the overall heating capabilities. We also demonstrated that the specific power absorption does not show a monotonous trend within the series in the investigated interval of temperatures, pointing to temperature-dependent competition of the Brownian and Néel contributions in heat release. Full article
(This article belongs to the Special Issue Synthesis, Development and Characterization of Magnetic Nanomaterials)
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