Nanomaterials

27 pages, 2102 KiB

Open AccessReview

Multifunctional Gold Nanorod for Therapeutic Applications and Pharmaceutical Delivery Considering Cellular Metabolic Responses, Oxidative Stress and Cellular Longevity

by Seyyed Mojtaba Mousavi, Seyyed Alireza Hashemi, Sargol Mazraedoost, Khadije Yousefi, Ahmad Gholami, Gity Behbudi, Seeram Ramakrishna, Navid Omidifar, Ali Alizadeh and Wei-Hung Chiang

Nanomaterials 2021, 11(7), 1868; https://doi.org/10.3390/nano11071868 - 20 Jul 2021

Cited by 22 | Viewed by 3844

Abstract

Multifunctional gold nanorods (GNR) have drawn growing interest in biomedical fields because of their excellent biocompatibility, ease of alteration, and special optical properties. The great advantage of using GNR in medicine is their application to Photothermal therapy (PPTT), which is possible thanks to [...] Read more.

Multifunctional gold nanorods (GNR) have drawn growing interest in biomedical fields because of their excellent biocompatibility, ease of alteration, and special optical properties. The great advantage of using GNR in medicine is their application to Photothermal therapy (PPTT), which is possible thanks to their ability to turn luminous energy into heat to cause cellular hyperthermia. For this purpose, the relevant articles between 1988 and 2020 were searched in databases such as John Wiley, Free paper, Scopus, Science Direct, and Springer to obtain the latest findings on multifunctional gold nanorods for therapeutic applications and pharmaceutical delivery. In this article, we review recent progress in diagnostic and therapeutic applications of multifunctional GNR, highlighting new information about their toxicity to various cellular categories, oxidative stress, cellular longevity, and their metabolic effects, such as the effect on the energy cycles and genetic structures. The methods for the synthesis and functionalization of GNR were surveyed. This review includes new information about GNR toxicity to various cellular categories and their metabolic effects. Full article

(This article belongs to the Special Issue Nanomaterials Engineering by Green Techniques: Concepts and Applications)

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14 pages, 3312 KiB

Open AccessArticle

A Comparative Study of the Influence of Nitrogen Content and Structural Characteristics of NiS/Nitrogen-Doped Carbon Nanocomposites on Capacitive Performances in Alkaline Medium

by Mohamed M. Abdelaal, Tzu-Cheng Hung, Saad Gomaa Mohamed, Chun-Chen Yang, Huei-Ping Huang and Tai-Feng Hung

Nanomaterials 2021, 11(7), 1867; https://doi.org/10.3390/nano11071867 - 20 Jul 2021

Cited by 16 | Viewed by 3196

Abstract

Supercapacitors (SCs) have been regarded as alternative electrochemical energy storage devices; however, optimizing the electrode materials to further enhance their specific energy and retain their rate capability is highly essential. Herein, the influence of nitrogen content and structural characteristics (i.e., porous and non-porous) [...] Read more.

Supercapacitors (SCs) have been regarded as alternative electrochemical energy storage devices; however, optimizing the electrode materials to further enhance their specific energy and retain their rate capability is highly essential. Herein, the influence of nitrogen content and structural characteristics (i.e., porous and non-porous) of the NiS/nitrogen-doped carbon nanocomposites on their electrochemical performances in an alkaline electrolyte is explored. Due to their distinctive surface and the structural features of the porous carbon (A-PVP-NC), the as-synthesized NiS/A-PVP-NC nanocomposites not only reveal a high wettability with 6 M KOH electrolyte and less polarization but also exhibit remarkable rate capability (101 C/g at 1 A/g and 74 C/g at 10 A/g). Although non-porous carbon (PI-NC) possesses more nitrogen content than the A-PVP-NC, the specific capacity output from the latter at 10 A/g is 3.7 times higher than that of the NiS/PI-NC. Consequently, our findings suggest that the surface nature and porous architectures that exist in carbon materials would be significant factors affecting the electrochemical behavior of electrode materials compared to nitrogen content. Full article

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

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4 pages, 210 KiB

Open AccessEditorial

Nanomaterials in Water Applications: Adsorbing Materials for Fluoride Removal

by Lei Huang, Kuilin Wan, Jia Yan, Lei Wang, Qian Li, Huabin Chen, Hongguo Zhang and Tangfu Xiao

Nanomaterials 2021, 11(7), 1866; https://doi.org/10.3390/nano11071866 - 20 Jul 2021

Cited by 8 | Viewed by 2649

Abstract

Fluoride is an important pollutant in many countries, such as China, India, Australia, the United States, Ethiopia, etc [...] Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

32 pages, 8622 KiB

Open AccessReview

Advances and Novel Perspectives on Colloids, Hydrogels, and Aerogels Based on Coordination Bonds with Biological Interest Ligands

by Noelia Maldonado and Pilar Amo-Ochoa

Nanomaterials 2021, 11(7), 1865; https://doi.org/10.3390/nano11071865 - 20 Jul 2021

Cited by 15 | Viewed by 3967

Abstract

This perspective article shows new advances in the synthesis of colloids, gels, and aerogels generated by combining metal ions and ligands of biological interest, such as nucleobases, nucleotides, peptides, or amino acids, among other derivatives. The characteristic dynamism of coordination bonds between metal [...] Read more.

This perspective article shows new advances in the synthesis of colloids, gels, and aerogels generated by combining metal ions and ligands of biological interest, such as nucleobases, nucleotides, peptides, or amino acids, among other derivatives. The characteristic dynamism of coordination bonds between metal center and biocompatible-type ligands, together with molecular recognition capability of these ligands, are crucial to form colloids and gels. These supramolecular structures are generated by forming weak van der Waals bonds such as hydrogen bonds or π–π stacking between the aromatic rings. Most gels are made up of nano-sized fibrillar networks, although their morphologies can be tuned depending on the synthetic conditions. These new materials respond to different stimuli such as pH, stirring, pressure, temperature, the presence of solvents, among others. For these reasons, they can trap and release molecules or metal ions in a controlled way allowing their application in drug delivery as antimicrobial and self-healable materials or sensors. In addition, the correct selection of the metal ion enables to build catalytic or luminescent metal–organic gels. Even recently, the use of these colloids as 3D-dimensional printable inks has been published. The elimination of the solvent trapped in the gels allows the transformation of these into metal–organic aerogels (MOAs) and metal–organic xerogels (MOXs), increasing the number of possible applications by generating new porous materials and composites useful in adsorption, conversion, and energy storage. The examples shown in this work allow us to visualize the current interest in this new type of material and their perspectives in the short-medium term. Furthermore, these investigations show that there is still a lot of work to be done, opening the door to new and interesting applications. Full article

(This article belongs to the Special Issue Preparation and Characterization of Nanomaterials with Multifunctional Properties)

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10 pages, 5642 KiB

Open AccessArticle

Low-Thermal-Budget Photonic Sintering of Hybrid Pastes Containing Submicron/Nano CuO/Cu₂O Particles

by Po-Hsiang Chiu, Wei-Han Cheng, Ming-Tsang Lee, Kiyokazu Yasuda and Jenn-Ming Song

Nanomaterials 2021, 11(7), 1864; https://doi.org/10.3390/nano11071864 - 20 Jul 2021

Cited by 9 | Viewed by 2557

Abstract

Copper oxide particles of various sizes and constituent phases were used to form conductive circuits by means of photonic sintering. With the assistance of extremely low-energy-density xenon flash pulses (1.34 J/cm²), a mixture of nano/submicron copper oxide particles can be reduced [...] Read more.

Copper oxide particles of various sizes and constituent phases were used to form conductive circuits by means of photonic sintering. With the assistance of extremely low-energy-density xenon flash pulses (1.34 J/cm²), a mixture of nano/submicron copper oxide particles can be reduced in several seconds to form electrical conductive copper films or circuits exhibiting an average thickness of 6 μm without damaging the underlying polymeric substrate, which is quite unique compared to commercial nano-CuO inks whose sintered structure is usually 1 μm or less. A mixture of submicron/nano copper oxide particles with a weight ratio of 3:1 and increasing the fraction of Cu₂O in the copper oxide both decrease the electrical resistivity of the reduced copper. Adding copper formate further improved the continuity of interconnects and, thereby, the electrical conductance. Exposure to three-pulse low-energy-density flashes yields an electrical resistivity of 64.6 μΩ·cm. This study not only shed the possibility to use heat-vulnerate polymers as substrate materials benefiting from extremely low-energy light sources, but also achieved photonic-sintered thick copper films through the adoption of submicron copper oxide particles. Full article

(This article belongs to the Special Issue Low-Dimensional Nanomaterials and Their Applications)

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13 pages, 5957 KiB

Open AccessArticle

Ab-Initio Spectroscopic Characterization of Melem-Based Graphitic Carbon Nitride Polymorphs

by Aldo Ugolotti and Cristiana Di Valentin

Nanomaterials 2021, 11(7), 1863; https://doi.org/10.3390/nano11071863 - 20 Jul 2021

Cited by 8 | Viewed by 3019

Abstract

Polymeric graphitic carbon nitride (gCN) compounds are promising materials in photoactivated electrocatalysis thanks to their peculiar structure of periodically spaced voids exposing reactive pyridinic N atoms. These are excellent sites for the adsorption of isolated transition metal atoms or small clusters that can [...] Read more.

Polymeric graphitic carbon nitride (gCN) compounds are promising materials in photoactivated electrocatalysis thanks to their peculiar structure of periodically spaced voids exposing reactive pyridinic N atoms. These are excellent sites for the adsorption of isolated transition metal atoms or small clusters that can highly enhance the catalytic properties. However, several polymorphs of gCN can be obtained during synthesis, differing for their structural and electronic properties that ultimately drive their potential as catalysts. The accurate characterization of the obtained material is critical for the correct rationalization of the catalytic results; however, an unambiguous experimental identification of the actual polymer is challenging, especially without any reference spectroscopic features for the assignment. In this work, we optimized several models of melem-based gCN, taking into account different degrees of polymerization and arrangement of the monomers, and we present a thorough computational characterization of their simulated XRD, XPS, and NEXAFS spectroscopic properties, based on state-of-the-art density functional theory calculations. Through this detailed study, we could identify the peculiar fingerprints of each model and correlate them with its structural and/or electronic properties. Theoretical predictions were compared with the experimental data whenever they were available. Full article

(This article belongs to the Special Issue Emerging Two-Dimensional Materials: Inspiring Nanotechnologies for Smart Energy Management)

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20 pages, 2048 KiB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 13 | Viewed by 4004

Abstract

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

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

(This article belongs to the Section Biology and Medicines)

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19 pages, 1166 KiB

Open AccessReview

Advancements in Assessments of Bio-Tissue Engineering and Viable Cell Delivery Matrices Using Bile Acid-Based Pharmacological Biotechnologies

by Armin Mooranian, Melissa Jones, Corina Mihaela Ionescu, Daniel Walker, Susbin Raj Wagle, Bozica Kovacevic, Jacqueline Chester, Thomas Foster, Edan Johnston, Momir Mikov and Hani Al-Salami

Nanomaterials 2021, 11(7), 1861; https://doi.org/10.3390/nano11071861 - 19 Jul 2021

Cited by 17 | Viewed by 3584

Abstract

The utilisation of bioartificial organs is of significant interest to many due to their versatility in treating a wide range of disorders. Microencapsulation has a potentially significant role in such organs. In order to utilise microcapsules, accurate characterisation and analysis is required to [...] Read more.

The utilisation of bioartificial organs is of significant interest to many due to their versatility in treating a wide range of disorders. Microencapsulation has a potentially significant role in such organs. In order to utilise microcapsules, accurate characterisation and analysis is required to assess their properties and suitability. Bioartificial organs or transplantable microdevices must also account for immunogenic considerations, which will be discussed in detail. One of the most characterized cases is the investigation into a bioartificial pancreas, including using microencapsulation of islets or other cells, and will be the focus subject of this review. Overall, this review will discuss the traditional and modern technologies which are necessary for the characterisation of properties for transplantable microdevices or organs, summarizing analysis of the microcapsule itself, cells and finally a working organ. Furthermore, immunogenic considerations of such organs are another important aspect which is addressed within this review. The various techniques, methodologies, advantages, and disadvantages will all be discussed. Hence, the purpose of this review is providing an updated examination of all processes for the analysis of a working, biocompatible artificial organ. Full article

(This article belongs to the Section Biology and Medicines)

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13 pages, 3453 KiB

Open AccessArticle

Copper Hexacyanoferrate Thin Film Deposition and Its Application to a New Method for Diffusion Coefficient Measurement

by Jeonghun Yun, Yeongae Kim, Caitian Gao, Moobum Kim, Jae Yoon Lee, Chul-Ho Lee, Tae-Hyun Bae and Seok Woo Lee

Nanomaterials 2021, 11(7), 1860; https://doi.org/10.3390/nano11071860 - 19 Jul 2021

Cited by 5 | Viewed by 4425

Abstract

The use of Prussian blue analogues (PBA) materials in electrochemical energy storage and harvesting has gained much interest, necessitating the further clarification of their electrochemical characteristics. However, there is no well-defined technique for manufacturing PBA-based microelectrochemical devices because the PBA film deposition method [...] Read more.

The use of Prussian blue analogues (PBA) materials in electrochemical energy storage and harvesting has gained much interest, necessitating the further clarification of their electrochemical characteristics. However, there is no well-defined technique for manufacturing PBA-based microelectrochemical devices because the PBA film deposition method has not been well studied. In this study, we developed the following deposition method for growing copper hexacyanoferrate (CuHCFe) thin film: copper thin film is immersed into a potassium hexacyanoferrate solution, following which the redox reaction induces the spontaneous deposition of CuHCFe thin film on the copper thin film. The film grown via this method showed compatibility with conventional photolithography processes, and the micropattern of the CuHCFe thin film was successfully defined by a lift-off process. A microelectrochemical device based on the CuHCFe thin film was fabricated via micropatterning, and the sodium ion diffusivity in CuHCFe was measured. The presented thin film deposition method can deposit PBAs on any surface, including insulating substrates, and it can extend the utilization of PBA thin films to various applications. Full article

(This article belongs to the Special Issue Highly Efficient Energy Harvesting Based on Nanomaterials)

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17 pages, 2095 KiB

Open AccessArticle

Efficient Biexciton Preparation in a Quantum Dot—Metal Nanoparticle System Using On-Off Pulses

by Athanasios Smponias, Dionisis Stefanatos and Emmanuel Paspalakis

Nanomaterials 2021, 11(7), 1859; https://doi.org/10.3390/nano11071859 - 19 Jul 2021

Cited by 14 | Viewed by 2676

Abstract

We consider a hybrid nanostructure composed by semiconductor quantum dot coupled to a metallic nanoparticle and investigate the efficient creation of biexciton state in the quantum dot, when starting from the ground state and using linearly polarized laser pulses with on-off modulation. With [...] Read more.

We consider a hybrid nanostructure composed by semiconductor quantum dot coupled to a metallic nanoparticle and investigate the efficient creation of biexciton state in the quantum dot, when starting from the ground state and using linearly polarized laser pulses with on-off modulation. With numerical simulations of the coupled system density matrix equations, we show that a simple on-off-on pulse-sequence, previously derived for the case of an isolated quantum dot, can efficiently prepare the biexciton state even in the presence of the nanoparticle, for various interparticle distances and biexciton energy shifts. The pulse durations in the sequence are obtained from the solution of a transcendental equation. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Quantum Technology, Sensor and Health Therapy Applications)

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34 pages, 2163 KiB

Open AccessReview

Periodontal and Dental Pulp Cell-Derived Small Extracellular Vesicles: A Review of the Current Status

by Shu Hua, Peter Mark Bartold, Karan Gulati, Corey Stephen Moran, Sašo Ivanovski and Pingping Han

Nanomaterials 2021, 11(7), 1858; https://doi.org/10.3390/nano11071858 - 19 Jul 2021

Cited by 38 | Viewed by 4912

Abstract

Extracellular vesicles (EVs) are membrane-bound lipid particles that are secreted by all cell types and function as cell-to-cell communicators through their cargos of protein, nucleic acid, lipids, and metabolites, which are derived from their parent cells. There is limited information on the isolation [...] Read more.

Extracellular vesicles (EVs) are membrane-bound lipid particles that are secreted by all cell types and function as cell-to-cell communicators through their cargos of protein, nucleic acid, lipids, and metabolites, which are derived from their parent cells. There is limited information on the isolation and the emerging therapeutic role of periodontal and dental pulp cell-derived small EVs (sEVs, <200 nm, or exosome). In this review, we discuss the biogenesis of three EV subtypes (sEVs, microvesicles and apoptotic bodies) and the emerging role of sEVs from periodontal ligament (stem) cells, gingival fibroblasts (or gingival mesenchymal stem cells) and dental pulp cells, and their therapeutic potential in vitro and in vivo. A review of the relevant methodology found that precipitation-based kits and ultracentrifugation are the two most common methods to isolate periodontal (dental pulp) cell sEVs. Periodontal (and pulp) cell sEVs range in size, from 40 nm to 2 μm, due to a lack of standardized isolation protocols. Nevertheless, our review found that these EVs possess anti-inflammatory, osteo/odontogenic, angiogenic and immunomodulatory functions in vitro and in vivo, via reported EV cargos of EV–miRNAs, EV–circRNAs, EV–mRNAs and EV–lncRNAs. This review highlights the considerable therapeutic potential of periodontal and dental pulp cell-derived sEVs in various regenerative applications. Full article

(This article belongs to the Special Issue Nano-Engineering Solutions for Dental Implant Applications)

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11 pages, 2940 KiB

Open AccessEditor’s ChoiceArticle

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

by Yuji Noguchi and Hiroki Matsuo

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

Cited by 9 | Viewed by 4633

Abstract

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

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

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

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12 pages, 57206 KiB

Open AccessArticle

Simultaneous Improvement of Yield Strength and Ductility at Cryogenic Temperature by Gradient Structure in 304 Stainless Steel

by Shuang Qin, Muxin Yang, Fuping Yuan and Xiaolei Wu

Nanomaterials 2021, 11(7), 1856; https://doi.org/10.3390/nano11071856 - 19 Jul 2021

Cited by 13 | Viewed by 3472

Abstract

The tensile properties and the corresponding deformation mechanism of the graded 304 stainless steel (ss) at both room and cryogenic temperatures were investigated and compared with those of the coarse-grained (CGed) 304 ss. Gradient structures were found to have excellent synergy of strength [...] Read more.

The tensile properties and the corresponding deformation mechanism of the graded 304 stainless steel (ss) at both room and cryogenic temperatures were investigated and compared with those of the coarse-grained (CGed) 304 ss. Gradient structures were found to have excellent synergy of strength and ductility at room temperature, and both the yield strength and the uniform elongation were found to be simultaneously improved at cryogenic temperature in the gradient structures, as compared to those for the CG sample. The hetero-deformation-induced (HDI) hardening was found to play a more important role in the gradient structures as compared to the CG sample and be more obvious at cryogenic temperature as compared to that at room temperature. The central layer in the gradient structures provides stronger strain hardening during tensile deformation at both temperatures, due to more volume fraction of martensitic transformation. The volume fraction of martensitic transformation in the gradient structures was found to be much higher at cryogenic temperature, resulting in a much stronger strain hardening at cryogenic temperature. The amount of martensitic transformation at the central layer of the gradient structures is observed to be even higher than that for the CG sample at cryogenic temperature, which is one of the origins for the simultaneous improvement of strength and ductility by the gradient structures at cryogenic temperature. Full article

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

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12 pages, 5362 KiB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 7 | Viewed by 2752

Abstract

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

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

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

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11 pages, 3846 KiB

Open AccessArticle

Robust Conductive Hydrogels with Ultrafast Self-Recovery and Nearly Zero Response Hysteresis for Epidermal Sensors

by Xiuru Xu, Chubin He, Feng Luo, Hao Wang and Zhengchun Peng

Nanomaterials 2021, 11(7), 1854; https://doi.org/10.3390/nano11071854 - 19 Jul 2021

Cited by 7 | Viewed by 3067

Abstract

Robust conductive hydrogels are in great demand for the practical applications of smart soft robots, epidermal electronics, and human–machine interactions. We successfully prepared nanoparticles enhanced polyacrylamide/hydroxypropyl guar gum/acryloyl-grafted chitosan quaternary ammonium salt/calcium ions/SiO₂ nanoparticles (PHC/Ca²⁺/SiO₂ NPs) conductive hydrogels. Owing [...] Read more.

Robust conductive hydrogels are in great demand for the practical applications of smart soft robots, epidermal electronics, and human–machine interactions. We successfully prepared nanoparticles enhanced polyacrylamide/hydroxypropyl guar gum/acryloyl-grafted chitosan quaternary ammonium salt/calcium ions/SiO₂ nanoparticles (PHC/Ca²⁺/SiO₂ NPs) conductive hydrogels. Owing to the stable chemical and physical hybrid crosslinking networks and reversible non-covalent interactions, the PHC/Ca²⁺/SiO₂ NPs conductive hydrogel showed good conductivity (~3.39 S/m), excellent toughness (6.71 MJ/m³), high stretchability (2256%), fast self-recovery (80% within 10 s, and 100% within 30 s), and good fatigue resistance. The maximum gauge factor as high as 66.99 was obtained, with a wide detectable strain range (from 0.25% to 500% strain), the fast response (25.00 ms) and recovery time (86.12 ms), excellent negligible response hysteresis, and good response stability. The applications of monitoring the human’s body movements were demonstrated, such as wrist bending and pulse tracking. Full article

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15 pages, 6554 KiB

Open AccessArticle

Exosomal Surface Protein Detection with Quantum Dots and Immunomagnetic Capture for Cancer Detection

by Vojtech Vinduska, Caleb Edward Gallops, Ryan O’Connor, Yongmei Wang and Xiaohua Huang

Nanomaterials 2021, 11(7), 1853; https://doi.org/10.3390/nano11071853 - 18 Jul 2021

Cited by 14 | Viewed by 4270

Abstract

Exosomes carry molecular contents reflective of parental cells and thereby hold great potential as a source of biomarkers for non-invasive cancer detection and monitoring. However, simple and rapid exosomal molecular detection remains challenging. Here, we report a facile method for exosome surface protein [...] Read more.

Exosomes carry molecular contents reflective of parental cells and thereby hold great potential as a source of biomarkers for non-invasive cancer detection and monitoring. However, simple and rapid exosomal molecular detection remains challenging. Here, we report a facile method for exosome surface protein detection using quantum dot coupled with immunomagnetic capture and enrichment. In this method, exosomes were captured by magnetic beads based on CD81 protein expression. Surface protein markers of interest were recognized by primary antibody and then detected by secondary antibody-conjugated quantum dot with fluorescent spectroscopy. Validated by ELISA, our method can specifically detect different surface markers on exosomes from different cancer cell lines and differentiate cancer exosomes from normal exosomes. The clinical potential was demonstrated with pilot plasma samples using HER2-positive breast cancer as the disease model. The results show that exosomes from HER2-positive breast cancer patients exhibited a five times higher level of HER2 expression than healthy controls. Exosomal HER2 showed strong diagnostic power for HER2-positive patients, with the area under the curve of 0.969. This quantum dot-based exosome method is rapid (less than 5 h) and only requires microliters of diluted plasma without pre-purification, practical for routine use for basic vesicle research, and clinical applications. Full article

(This article belongs to the Section Biology and Medicines)

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20 pages, 4311 KiB

Open AccessArticle

A Green Nanostructured Pesticide to Control Tomato Bacterial Speck Disease

by Daniele Schiavi, Rosa Balbi, Stefano Giovagnoli, Emidio Camaioni, Ermelinda Botticella, Francesco Sestili and Giorgio Mariano Balestra

Nanomaterials 2021, 11(7), 1852; https://doi.org/10.3390/nano11071852 - 18 Jul 2021

Cited by 20 | Viewed by 4622

Abstract

Bacterial speck disease, caused by Pseudomonas syringae pv. tomato (Pst), is one of the most pervasive biological adversities in tomato cultivation, in both industrial and in table varieties. In this work synthesis, biochemical and antibacterial properties of a novel organic nanostructured pesticide composed [...] Read more.

Bacterial speck disease, caused by Pseudomonas syringae pv. tomato (Pst), is one of the most pervasive biological adversities in tomato cultivation, in both industrial and in table varieties. In this work synthesis, biochemical and antibacterial properties of a novel organic nanostructured pesticide composed of chitosan hydrochloride (CH) as active ingredient, cellulose nanocrystals (CNC) as nanocarriers and starch as excipient were evaluated. In order to study the possibility of delivering CH, the effects of two different types of starches, extracted from a high amylose bread wheat (high amylose starch—HA Starch) and from a control genotype (standard starch—St Starch), were investigated. Nanostructured microparticles (NMP) were obtained through the spray-drying technique, revealing a CH loading capacity proximal to 50%, with a CH release of 30% for CH-CNC-St Starch NMP and 50% for CH-CNC-HA Starch NMP after 24 h. Both NMP were able to inhibit bacterial growth in vitro when used at 1% w/v. Moreover, no negative effects on vegetative growth were recorded when NMP were foliar applied on tomato plants. Proposed nanostructured pesticides showed the capability of diminishing Pst epiphytical survival during time, decreasing disease incidence and severity (from 45% to 49%), with results comparable to one of the most used cupric salt (hydroxide), pointing out the potential use of CH-CNC-Starch NMP as a sustainable and innovative ally in Pst control strategies. Full article

(This article belongs to the Special Issue Advances in Nanopesticides: Synthesis, Characterization, and Applications)

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11 pages, 3396 KiB

Open AccessArticle

Tunable Transmissive Terahertz Linear Polarizer for Arbitrary Linear Incidence Based on Low-Dimensional Metamaterials

by Zhenyu Yang, Dahai Yu, Huiping Zhang, Anqi Yu, Xuguang Guo, Yuxiang Ren, Xiaofei Zang, Alexei V. Balakin and Alexander P. Shkurinov

Nanomaterials 2021, 11(7), 1851; https://doi.org/10.3390/nano11071851 - 18 Jul 2021

Cited by 5 | Viewed by 2487

Abstract

In this work, we propose a structure consisting of three metamaterial layers and a metallic grating layer to rotate the polarization of arbitrary linearly polarized incidence to the y-direction with high transmissivity by electrically tuning these metamaterials. The transfer matrix method together with [...] Read more.

In this work, we propose a structure consisting of three metamaterial layers and a metallic grating layer to rotate the polarization of arbitrary linearly polarized incidence to the y-direction with high transmissivity by electrically tuning these metamaterials. The transfer matrix method together with a harmonic oscillator model is adopted to theoretically study the proposed structure. Numerical simulation based on the finite difference time-domain method is performed assuming that the metamaterial layers are constituted by graphene ribbon arrays. The calculation and simulation results show that the Drude absorption is responsible for the polarization rotation. Fermi level and scattering rate of graphene are important for the transmissivity. For a polarization rotation of around 90°, the thickness of either the upper or lower dielectric separations influences the transmission window. For a polarization rotation of around 45° and 135°, the lower dielectric separations decide the frequency of the transmission window, while the upper dielectric separations just slightly influence the transmissivity. Full article

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

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16 pages, 3034 KiB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 41 | Viewed by 5623

Abstract

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

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

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

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22 pages, 13481 KiB

Open AccessArticle

Synergistic Effect of Nanofluids and Surfactants on Heavy Oil Recovery and Oil-Wet Calcite Wettability

by Jinjian Hou and Lingyu Sun

Nanomaterials 2021, 11(7), 1849; https://doi.org/10.3390/nano11071849 - 17 Jul 2021

Cited by 13 | Viewed by 2668

Abstract

In recent years, unconventional oils have shown a huge potential for exploitation. Abundant reserves of carbonate asphalt rocks with a high oil content have been found; however, heavy oil and carbonate minerals have a high interaction force, which makes oil-solid separation difficult when [...] Read more.

In recent years, unconventional oils have shown a huge potential for exploitation. Abundant reserves of carbonate asphalt rocks with a high oil content have been found; however, heavy oil and carbonate minerals have a high interaction force, which makes oil-solid separation difficult when using traditional methods. Although previous studies have used nanofluids or surfactant alone to enhance oil recovery, the minerals were sandstones. For carbonate asphalt rocks, there is little research on the synergistic effect of nanofluids and surfactants on heavy oil recovery by hot-water-based extraction. In this study, we used nanofluids and surfactants to enhance oil recovery from carbonate asphalt rocks synergistically based on the HWBE process. In order to explore the synergistic mechanism, the alterations of wettability due to the use of nanofluids and surfactants were studied. Nanofluids alone could render the oil-wet calcite surface hydrophilic, and the resulting increase in hydrophilicity of calcite surfaces treated with different nanofluids followed the order of SiO₂ > MgO > TiO₂ > ZrO₂ > γ-Al₂O₃. The concentration, salinity, and temperature of nanofluids influenced the oil-wet calcite wettability, and for SiO₂ nanofluids, the optimal nanofluid concentration was 0.2 wt%; the optimal salinity was 3 wt%; and the contact angle decreased as the temperature increased. Furthermore, the use of surfactants alone made the oil-wet calcite surface more hydrophilic, according to the following order: sophorolipid (45.9°) > CTAB (49°) > rhamnolipid (53.4°) > TX-100 (58.4°) > SDS (67.5°). The elemental analysis along with AFM and SEM characterization showed that nanoparticles were adsorbed onto the mineral surface, resulting in greater hydrophilicity of the oil-wet calcite surface, and the roughness was related to the wettability. Surfactant molecules could aid in the release of heavy oil from the calcite surface, which exposes the uncovered calcite surface to its surroundings; additionally, some surfactants adsorbed onto the oil-wet calcite surface, and the combined role made the oil-wet calcite surface hydrophilic. In conclusion, the study showed that hybrid nanofluids showed a better effect on wettability alteration, and the use of nanofluids and surfactants together resulted in synergistic alteration of oil-wet calcite surface wettability. Full article

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

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6 pages, 241 KiB

Open AccessEditorial

Nanostructural Materials with Rare Earth Ions: Synthesis, Physicochemical Characterization, Modification and Applications

by Rafal J. Wiglusz

Nanomaterials 2021, 11(7), 1848; https://doi.org/10.3390/nano11071848 - 16 Jul 2021

Cited by 3 | Viewed by 2112

Abstract

The success of nanotechnology in the field of physical, chemical and medical sciences has started revolutionizing the drug delivery science and theranostics (therapy and diagnostics) [...] Full article

(This article belongs to the Special Issue Nanostructural Materials with Rare Earth Ions: Synthesis, Physicochemical Characterization, Modification and Applications)

11 pages, 2285 KiB

Open AccessArticle

Highly Enhanced OER Performance by Er-Doped Fe-MOF Nanoarray at Large Current Densities

by Yan Ma, Yujie Miao, Guomei Mu, Dunmin Lin, Chenggang Xu, Wen Zeng and Fengyu Xie

Nanomaterials 2021, 11(7), 1847; https://doi.org/10.3390/nano11071847 - 16 Jul 2021

Cited by 15 | Viewed by 4585

Abstract

Great expectations have been held for the electrochemical splitting of water for producing hydrogen as a significant carbon-neutral technology aimed at solving the global energy crisis and greenhouse gas issues. However, the oxygen evolution reaction (OER) process must be energetically catalyzed over a [...] Read more.

Great expectations have been held for the electrochemical splitting of water for producing hydrogen as a significant carbon-neutral technology aimed at solving the global energy crisis and greenhouse gas issues. However, the oxygen evolution reaction (OER) process must be energetically catalyzed over a long period at high output, leading to challenges for efficient and stable processing of electrodes for practical purposes. Here, we first prepared Fe-MOF nanosheet arrays on nickel foam via rare-earth erbium doping (Er_0.4 Fe-MOF/NF) and applied them as OER electrocatalysts. The Er_0.4 Fe-MOF/NF exhibited wonderful OER performance and could yield a 100 mA cm⁻² current density at an overpotential of 248 mV with outstanding long-term electrochemical durability for at least 100 h. At large current densities of 500 and 1000 mA cm⁻², overpotentials of only 297 mV and 326 mV were achieved, respectively, revealing its potential in industrial applications. The enhancement was attributed to the synergistic effects of the Fe and Er sites, with Er playing a supporting role in the engineering of the electronic states of the Fe sites to endow them with enhanced OER activity. Such a strategy of engineering the OER activity of Fe-MOF via rare-earth ion doping paves a new avenue to design other MOF catalysts for industrial OER applications. Full article

(This article belongs to the Special Issue Design of Nanocatalysts and Electrodes: Application to Fuel Cell and Water Electrolysis)

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14 pages, 5544 KiB

Open AccessArticle

Combination of Selective Etching and Impregnation toward Hollow Mesoporous Bioactive Glass Nanoparticles

by Nurshen Mutlu, Ana Maria Beltrán, Qaisar Nawaz, Martin Michálek, Aldo R. Boccaccini and Kai Zheng

Nanomaterials 2021, 11(7), 1846; https://doi.org/10.3390/nano11071846 - 16 Jul 2021

Cited by 11 | Viewed by 3571

Abstract

In this study, binary SiO₂-CaO hollow mesoporous bioactive glass nanoparticles (HMBGNs) are prepared by combing selective etching and impregnation strategies. Spherical silica particles (SiO₂ NPs) are used as hard cores to assemble cetyltrimethylammonium bromide (CTAB)/silica shells, which are later removed [...] Read more.

In this study, binary SiO₂-CaO hollow mesoporous bioactive glass nanoparticles (HMBGNs) are prepared by combing selective etching and impregnation strategies. Spherical silica particles (SiO₂ NPs) are used as hard cores to assemble cetyltrimethylammonium bromide (CTAB)/silica shells, which are later removed by selective etching to generate a hollow structure. After the removal of CTAB by calcination, the mesoporous shell of particles is formed. Calcium (Ca) is incorporated into the particles using impregnation by soaking the etched SiO₂ NPs in calcium nitrate aqueous solution. The amount of incorporated Ca is tailorable by controlling the ratio of SiO₂ NPs:calcium nitrate in the soaking solution. The produced HMBGNs are bioactive, as indicated by the rapid formation of hydroxyapatite on their surfaces after immersion in simulated body fluid. In a direct culture with MC3T3-E1 cells, HMBGNs were shown to exhibit concentration-dependent cytotoxicity and can stimulate osteogenic differentiation of MC3T3-E1 cells at concentrations of 1, 0.5, and 0.25 mg/mL. Our results indicate that the combination of selective etching and impregnation is a feasible approach to produce hierarchical HMBGNs. The produced hollow particles have potential in drug delivery and bone tissue regeneration applications, and should be further investigated in detailed in vitro and in vivo studies. Full article

(This article belongs to the Special Issue Nanoparticles for Bio-Medical Applications)

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19 pages, 10254 KiB

Open AccessArticle

Effect of the Processing on the Resistance–Strain Response of Multiwalled Carbon Nanotube/Natural Rubber Composites for Use in Large Deformation Sensors

by Xingyao Liu, Rongxin Guo, Rui Li, Hui Liu, Zhengming Fan, Yang Yang and Zhiwei Lin

Nanomaterials 2021, 11(7), 1845; https://doi.org/10.3390/nano11071845 - 16 Jul 2021

Cited by 22 | Viewed by 2677

Abstract

The dispersion, electrical conductivities, mechanical properties and resistance–strain response behaviors of multiwalled carbon nanotube (MWCNT)/natural rubber (NR) composites synthesized by the different processing conditions are systematically investigated at both macro- and micro-perspectives. Compared with the solution and flocculation methods, the two roll method [...] Read more.

The dispersion, electrical conductivities, mechanical properties and resistance–strain response behaviors of multiwalled carbon nanotube (MWCNT)/natural rubber (NR) composites synthesized by the different processing conditions are systematically investigated at both macro- and micro-perspectives. Compared with the solution and flocculation methods, the two roll method produced the best MWCNTs distribution since the materials are mixed by strong shear stress between the two rolls. An excellent segregated conductive network is formed and that a low percolation threshold is obtained (~1 wt.%) by the two roll method. Different from the higher increases in conductivity for the composites obtained by the solution and flocculation methods when the MWCNT content is higher than 3 wt.%, the composite prepared by the two roll method displays obvious improvements in its mechanical properties. In addition, the two roll method promotes good stability, repeatability, and durability along with an ultrahigh sensitivity (GF_max = 974.2) and a large strain range (ε = 109%). The ‘shoulder peak’ phenomenon has not been observed in the composite prepared by the two roll method, confirming its potential for application as a large deformation monitoring sensor. Moreover, a mathematical model is proposed to explain the resistance–strain sensing mechanism. Full article

(This article belongs to the Special Issue Preparation and Characterization of Nanomaterials with Multifunctional Properties)

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8 pages, 1005 KiB

Open AccessArticle

Colloidal Assemblies Composed of Polymeric Micellar/Emulsified Systems Integrate Cancer Therapy Combining a Tumor-Associated Antigen Vaccine and Chemotherapeutic Regimens

by Chiung-Yi Huang, Shu-Yu Lin, Tsu-An Hsu, Hsing-Pang Hsieh and Ming-Hsi Huang

Nanomaterials 2021, 11(7), 1844; https://doi.org/10.3390/nano11071844 - 16 Jul 2021

Cited by 2 | Viewed by 2326

Abstract

Integrative medicine comprising a tumor-associated antigen vaccine and chemotherapeutic regimens has provided new insights into cancer therapy. In this study, the AB-type diblock copolymers poly(ethylene glycol)–polylactide (PEG–PLA) were subjected to the dispersion of poorly water-soluble molecules in aqueous solutions. The physicochemical behavior of [...] Read more.

Integrative medicine comprising a tumor-associated antigen vaccine and chemotherapeutic regimens has provided new insights into cancer therapy. In this study, the AB-type diblock copolymers poly(ethylene glycol)–polylactide (PEG–PLA) were subjected to the dispersion of poorly water-soluble molecules in aqueous solutions. The physicochemical behavior of the chemotherapeutic agent DBPR114 in the PEG–PLA-polymeric aqueous solution was investigated by dynamic light scattering (DLS) technology. In vitro cell culture indicated that replacing the organic solvent DMSO with PEG–PLA polymeric micelles could maintain the anti-proliferative effect of DBPR114 on leukemia cell lines. A murine tumor-associated antigen vaccine model was established in tumor-bearing mice to determine the effectiveness of these formulas in inducing tumor regression. The results demonstrated that the therapeutic treatments effectively reinforced each other via co-delivery of antitumor drug/antigen agents to synergistically integrate the efficacy of cancer therapy. Our findings support the potential use of polymeric micellar systems for aqueous solubilization and expansion of antitumor activity intrinsic to DBPR114 and tumor-associated antigen therapy. Full article

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

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12 pages, 3130 KiB

Open AccessArticle

Construction of Novel Nanocomposites (Cu-MOF/GOD@HA) for Chemodynamic Therapy

by Ya-Nan Hao, Cong-Cong Qu, Yang Shu, Jian-Hua Wang and Wei Chen

Nanomaterials 2021, 11(7), 1843; https://doi.org/10.3390/nano11071843 - 16 Jul 2021

Cited by 30 | Viewed by 5467

Abstract

The emerging chemodynamic therapy (CDT) has received an extensive attention in recent years. However, the efficiency of CDT is influenced due to the limitation of H₂O₂ in tumor. In this study, we designed and synthesized a novel core-shell nanostructure, Cu-metal [...] Read more.

The emerging chemodynamic therapy (CDT) has received an extensive attention in recent years. However, the efficiency of CDT is influenced due to the limitation of H₂O₂ in tumor. In this study, we designed and synthesized a novel core-shell nanostructure, Cu-metal organic framework (Cu-MOF)/glucose oxidase (GOD)@hyaluronic acid (HA) (Cu-MOF/GOD@HA) for the purpose of improving CDT efficacy by increasing H₂O₂ concentration and cancer cell targeting. In this design, Cu-MOF act as a CDT agent and GOD carrier. Cu(II) in Cu-MOF are reduced to Cu(I) by GSH to obtain Cu(I)-MOF while GSH is depleted. The depletion of GSH reinforces the concentration of H₂O₂ in tumor to improve the efficiency of CDT. The resultant Cu(I)-MOF catalyze H₂O₂ to generate hydroxyl radicals (·OH) for CDT. GOD can catalyze glucose (Glu) to supply H₂O₂ for CDT enhancement. HA act as a targeting molecule to improve the targeting ability of Cu-MOF/GOD@HA to the tumor cells. In addition, after loading with GOD and coating with HA, the proportion of Cu(I) in Cu-MOF/GOD@HA is increased compared with the proportion of Cu(I) in Cu-MOF. This phenomenon may shorten the reactive time from Cu-MOF to Cu(I)-MOF. The CDT enhancement as a result of GOD and HA effects in Cu-MOF/GOD@HA was evidenced by in vitro cell and in vivo animal studies. Full article

(This article belongs to the Special Issue Luminescence Nanomaterials and Applications)

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18 pages, 3848 KiB

Open AccessArticle

Extraordinary Nanocrystalline Pb Whisker Growth from Bi-Mg-Pb Pools in Aluminum Alloy 6026 Moderated through Oriented Attachment

by Matic Jovičević-Klug, Patricia Jovičević-Klug, Tina Sever, Darja Feizpour and Bojan Podgornik

Nanomaterials 2021, 11(7), 1842; https://doi.org/10.3390/nano11071842 - 16 Jul 2021

Cited by 4 | Viewed by 2944

Abstract

The elucidation of spontaneous growth of metal whiskers from metal surfaces is still ongoing, with the mainstream research conducted on Sn whiskers. This work reports on the discovery of Pb whisker growth from Bi-Mg-Pb solid pools found in common machinable aluminum alloy. The [...] Read more.

The elucidation of spontaneous growth of metal whiskers from metal surfaces is still ongoing, with the mainstream research conducted on Sn whiskers. This work reports on the discovery of Pb whisker growth from Bi-Mg-Pb solid pools found in common machinable aluminum alloy. The whiskers and hillocks display unique morphologies and complex growth that have not been documented beforehand. In contrast to typical understanding of whisker growth, the presented Pb whiskers show a clear nanocrystalline induced growth mechanism, which is a novel concept. Furthermore, the investigated whiskers are also found to be completely composed of nanocrystals throughout their entire length. The performed research gives new insight into nucleation and growth of metal whiskers, which raises new theoretical questions and challenges current theories of spontaneous metal whisker growth. Additionally, this work provides the first microscopic confirmation of recrystallization growth theory of whiskers that relates to oriented attachment of nanocrystals formed within an amorphous metallic matrix. The impact of mechanical stress, generated through Bi oxidation within the pools, is theoretically discussed with relation to the observed whisker and hillock growth. The newly discovered nanocrystalline growth provides a new step towards understanding spontaneous metal whisker growth and possibility of developing nanostructures for potential usage in sensing and electronics applications. Full article

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27 pages, 1577 KiB

Open AccessReview

Nanotechnology Integration for SARS-CoV-2 Diagnosis and Treatment: An Approach to Preventing Pandemic

by Syed Mohammed Basheeruddin Asdaq, Abu Md Ashif Ikbal, Ram Kumar Sahu, Bedanta Bhattacharjee, Tirna Paul, Bhargab Deka, Santosh Fattepur, Retno Widyowati, Joshi Vijaya, Mohammed Al mohaini, Abdulkhaliq J. Alsalman, Mohd. Imran, Sreeharsha Nagaraja, Anroop B. Nair, Mahesh Attimarad and Katharigatta N. Venugopala

Nanomaterials 2021, 11(7), 1841; https://doi.org/10.3390/nano11071841 - 16 Jul 2021

Cited by 19 | Viewed by 6146

Abstract

The SARS-CoV-2 outbreak is the COVID-19 disease, which has caused massive health devastation, prompting the World Health Organization to declare a worldwide health emergency. The corona virus infected millions of people worldwide, and many died as a result of a lack of particular [...] Read more.

The SARS-CoV-2 outbreak is the COVID-19 disease, which has caused massive health devastation, prompting the World Health Organization to declare a worldwide health emergency. The corona virus infected millions of people worldwide, and many died as a result of a lack of particular medications. The current emergency necessitates extensive therapy in order to stop the spread of the coronavirus. There are various vaccinations available, but no validated COVID-19 treatments. Since its outbreak, many therapeutics have been tested, including the use of repurposed medications, nucleoside inhibitors, protease inhibitors, broad spectrum antivirals, convalescence plasma therapies, immune-modulators, and monoclonal antibodies. However, these approaches have not yielded any outcomes and are mostly used to alleviate symptoms associated with potentially fatal adverse drug reactions. Nanoparticles, on the other hand, may prove to be an effective treatment for COVID-19. They can be designed to boost the efficacy of currently available antiviral medications or to trigger a rapid immune response against COVID-19. In the last decade, there has been significant progress in nanotechnology. This review focuses on the virus’s basic structure, pathogenesis, and current treatment options for COVID-19. This study addresses nanotechnology and its applications in diagnosis, prevention, treatment, and targeted vaccine delivery, laying the groundwork for a successful pandemic fight. Full article

(This article belongs to the Special Issue Nanomaterials for Biomedical and Biotechnological Applications)

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19 pages, 4746 KiB

Open AccessEditor’s ChoiceArticle

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

by Penghui Zhu, Jiahao Han and Wilhelm Pfleging

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

Cited by 24 | Viewed by 3804

Abstract

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

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

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

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19 pages, 1491 KiB

Open AccessArticle

Anomalous Terminal Shear Viscosity Behavior of Polycarbonate Nanocomposites Containing Grafted Nanosilica Particles

by Vaidyanath Ramakrishnan, Johannes G. P. Goossens, Theodorus L. Hoeks and Gerrit W. M. Peters

Nanomaterials 2021, 11(7), 1839; https://doi.org/10.3390/nano11071839 - 15 Jul 2021

Cited by 2 | Viewed by 3613

Abstract

Viscosity controls an important issue in polymer processing. This paper reports on the terminal viscosity behavior of a polymer melt containing grafted nanosilica particles. The melt viscosity behavior of the nanocomposites was found to depend on the interaction between the polymer matrix and [...] Read more.

Viscosity controls an important issue in polymer processing. This paper reports on the terminal viscosity behavior of a polymer melt containing grafted nanosilica particles. The melt viscosity behavior of the nanocomposites was found to depend on the interaction between the polymer matrix and the nanoparticle surface. In the case of polycarbonate (PC) nanocomposites, the viscosity decreases by approximately 25% at concentrations below 0.7 vol% of nanosilica, followed by an increase at higher concentrations. Chemical analysis shows that the decrease in viscosity can be attributed to in situ grafting of PC on the nanosilica surface, leading to a lower entanglement density around the nanoparticle. The thickness of the graft layer was found to be of the order of the tube diameter, with the disentangled zone being approximately equal to the radius of gyration (

R_{g}

) polymer chain. Furthermore, it is shown that the grafting has an effect on the motion of the PC chains at all timescales. Finally, the viscosity behavior in the PC nanocomposites was found to be independent of the molar mass of PC. The PC data are compared with polystyrene nanocomposites, for which the interaction between the polymer and nanoparticles is absent. The results outlined in this paper can be utilized for applications with low shear processing conditions, e.g., rotomolding, 3D printing, and multilayer co-extrusion. Full article

(This article belongs to the Special Issue Rheological, Thermal and Transport Properties of Polymeric Nanocomposites)

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Nanomaterials, Volume 11, Issue 7 (July 2021) – 240 articles

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