Nanomaterials

5601 KiB

Open AccessArticle

A Sustainable Approach to Fabricating Ag Nanoparticles/PVA Hybrid Nanofiber and Its Catalytic Activity

by Yongde Meng

Nanomaterials 2015, 5(2), 1124-1135; https://doi.org/10.3390/nano5021124 - 23 Jun 2015

Cited by 109 | Viewed by 7116

Ag nanoparticles were synthesized by using Ficus altissima Blume leaf extract as a reducing agent at room temperature. The resulting Ag nanoparticles/PVA mixture was employed to create Ag nanoparticles/PVA (polyvinyl alcohol) hybrid nanofibers via an electrospinning technique. The obtained nanofibers were confirmed by [...] Read more.

Ag nanoparticles were synthesized by using Ficus altissima Blume leaf extract as a reducing agent at room temperature. The resulting Ag nanoparticles/PVA mixture was employed to create Ag nanoparticles/PVA (polyvinyl alcohol) hybrid nanofibers via an electrospinning technique. The obtained nanofibers were confirmed by means of UV-Vis spectroscopy, The X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and then tested to catalyze KBH₄ reduction of methylene blue (MB). The catalytic results demonstrate that the MB can be reduced completely within 15 min. In addition, the Ag nanoparticles/PVA hybrid nanofibers show reusability for three cycles with no obvious losses in degradation ratio of the MB. Full article

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

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6955 KiB

Open AccessCommentary

Dynamism of Stimuli-Responsive Nanohybrids: Environmental Implications

by Jaime Plazas-Tuttle, Lewis S. Rowles III, Hao Chen, Joseph H. Bisesi, Jr., Tara Sabo-Attwood and Navid B. Saleh

Nanomaterials 2015, 5(2), 1102-1123; https://doi.org/10.3390/nano5021102 - 16 Jun 2015

Cited by 19 | Viewed by 7177

Abstract

Nanomaterial science and design have shifted from generating single passive nanoparticles to more complex and adaptive multi-component nanohybrids. These adaptive nanohybrids (ANHs) are designed to simultaneously perform multiple functions, while actively responding to the surrounding environment. ANHs are engineered for use as drug [...] Read more.

Nanomaterial science and design have shifted from generating single passive nanoparticles to more complex and adaptive multi-component nanohybrids. These adaptive nanohybrids (ANHs) are designed to simultaneously perform multiple functions, while actively responding to the surrounding environment. ANHs are engineered for use as drug delivery carriers, in tissue-engineered templates and scaffolds, adaptive clothing, smart surface coatings, electrical switches and in platforms for diversified functional applications. Such ANHs are composed of carbonaceous, metallic or polymeric materials with stimuli-responsive soft-layer coatings that enable them to perform such switchable functions. Since ANHs are engineered to dynamically transform under different exposure environments, evaluating their environmental behavior will likely require new approaches. Literature on polymer science has established a knowledge core on stimuli-responsive materials. However, translation of such knowledge to environmental health and safety (EHS) of these ANHs has not yet been realized. It is critical to investigate and categorize the potential hazards of ANHs, because exposure in an unintended or shifting environment could present uncertainty in EHS. This article presents a perspective on EHS evaluation of ANHs, proposes a principle to facilitate their identification for environmental evaluation, outlines a stimuli-based classification for ANHs and discusses emerging properties and dynamic aspects for systematic EHS evaluation. Full article

(This article belongs to the Special Issue Advancements in Nanotoxicology)

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6567 KiB

Open AccessArticle

Hybrid Mesoporous Silicas and Microporous POSS-Based Frameworks Incorporating Evaporation-Induced Self-Assembly

by Jheng-Guang Li, Wei-Cheng Chu and Shiao-Wei Kuo

Nanomaterials 2015, 5(2), 1087-1101; https://doi.org/10.3390/nano5021087 - 16 Jun 2015

Cited by 12 | Viewed by 7513

Abstract

We fabricated a series of mesoporous silicas and mesoporous organosilicates with hierarchical porosity through evaporation-induced self-assembly using Pluronic F127 as a template in this study. We could tailor the mesophase of each mesoporous silica sample by varying the weight ratio of its two [...] Read more.

We fabricated a series of mesoporous silicas and mesoporous organosilicates with hierarchical porosity through evaporation-induced self-assembly using Pluronic F127 as a template in this study. We could tailor the mesophase of each mesoporous silica sample by varying the weight ratio of its two silica sources: tetraethyl orthosilicate (TEOS) and triethoxysilane hydrosilylated octavinyl polyhedral oligomeric silsesquioxane (OV-POSS-SILY). The mesophases ranged from an ordered body-centered cubic (bcc) structure (TEOS alone) to ordered face-centered cubic (fcc) structure (10 and 20 wt.% of OV-POSS-SILY) and finally to disordered spherical pores (≥30 wt.% of OV-POSS-SILY). We used small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) to study the transformations of these mesophases, while N₂ isotherm sorption curves revealed the porosities of these mesoporous silicate samples. Moreover, ²⁹Si CP/MAS solid state nuclear magnetic resonance spectroscopy allowed us to analyze the compositions of the POSS-containing silicate frameworks. Such functional mesoporous silica samples incorporating microporous POSS building units have potential applications in various systems, including optical and electronic devices. Full article

(This article belongs to the Special Issue Frontiers in Mesoporous Nanomaterials)

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3933 KiB

Open AccessArticle

Examination of Single-Walled Carbon Nanotubes Uptake and Toxicity from Dietary Exposure: Tracking Movement and Impacts in the Gastrointestinal System

by Joseph H. Bisesi, Jr., Thuy Ngo, Satvika Ponnavolu, Keira Liu, Candice M. Lavelle, A.R.M. Nabiul Afrooz, Navid B. Saleh, P. Lee Ferguson, Nancy D. Denslow and Tara Sabo-Attwood

Nanomaterials 2015, 5(2), 1066-1086; https://doi.org/10.3390/nano5021066 - 12 Jun 2015

Cited by 37 | Viewed by 7641

Abstract

Previous studies indicate that exposure of fish to pristine single-walled carbon nanotubes (SWCNTs) by oral gavage, causes no overt toxicity, and no appreciable absorption has been observed. However, in the environment, SWCNTs are likely to be present in dietary sources, which may result [...] Read more.

Previous studies indicate that exposure of fish to pristine single-walled carbon nanotubes (SWCNTs) by oral gavage, causes no overt toxicity, and no appreciable absorption has been observed. However, in the environment, SWCNTs are likely to be present in dietary sources, which may result in differential impacts on uptake and biological effects. Additionally, the potential of these materials to sorb nutrients (proteins, carbohydrates, and lipids) while present in the gastrointestinal (GI) tract may lead to nutrient depletion conditions that impact processes such as growth and reproduction. To test this phenomenon, fathead minnows were fed a commercial diet either with or without SWCNTs for 96 h. Tracking and quantification of SWCNTs using near-infrared fluorescence (NIRF) imaging during feeding studies showed the presence of food does not facilitate transport of SWCNTs across the intestinal epithelia. Targeting genes shown to be responsive to nutrient depletion (peptide transporters, peptide hormones, and lipases) indicated that pept2, a peptide transporter, and cck, a peptide hormone, showed differential mRNA expression by 96 h, a response that may be indicative of nutrient limitation. The results of the current study increase our understanding of the movement of SWCNTs through the GI tract, while the changes in nutrient processing genes highlight a novel mechanism of sublethal toxicity in aquatic organisms. Full article

(This article belongs to the Special Issue Advancements in Nanotoxicology)

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1357 KiB

Open AccessReview

Origin and Future of Plasmonic Optical Tweezers

by Jer-Shing Huang and Ya-Tang Yang

Nanomaterials 2015, 5(2), 1048-1065; https://doi.org/10.3390/nano5021048 - 12 Jun 2015

Cited by 52 | Viewed by 10139

Abstract

Plasmonic optical tweezers can overcome the diffraction limits of conventional optical tweezers and enable the trapping of nanoscale objects. Extension of the trapping and manipulation of nanoscale objects with nanometer position precision opens up unprecedented opportunities for applications in the fields of biology, [...] Read more.

Plasmonic optical tweezers can overcome the diffraction limits of conventional optical tweezers and enable the trapping of nanoscale objects. Extension of the trapping and manipulation of nanoscale objects with nanometer position precision opens up unprecedented opportunities for applications in the fields of biology, chemistry and statistical and atomic physics. Potential applications include direct molecular manipulation, lab-on-a-chip applications for viruses and vesicles and the study of nanoscale transport. This paper reviews the recent research progress and development bottlenecks and provides an overview of possible future directions in this field. Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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Open AccessArticle

Crosslinked Carbon Nanotubes/Polyaniline Composites as a Pseudocapacitive Material with High Cycling Stability

by Dong Liu, Xue Wang, Jinxing Deng, Chenglong Zhou, Jinshan Guo and Peng Liu

Nanomaterials 2015, 5(2), 1034-1047; https://doi.org/10.3390/nano5021034 - 11 Jun 2015

Cited by 55 | Viewed by 8895

Abstract

The poor cycling stability of polyaniline (PANI) limits its practical application as a pseudocapacitive material due to the volume change during the charge-discharge procedure. Herein, crosslinked carbon nanotubes/polyaniline (C-CNTs/PANI) composites had been designed by the in situ chemical oxidative polymerization of aniline in [...] Read more.

The poor cycling stability of polyaniline (PANI) limits its practical application as a pseudocapacitive material due to the volume change during the charge-discharge procedure. Herein, crosslinked carbon nanotubes/polyaniline (C-CNTs/PANI) composites had been designed by the in situ chemical oxidative polymerization of aniline in the presence of crosslinked carbon nanotubes (C-CNTs), which were obtained by coupling of the functionalized carbon nanotubes with 1,4-benzoquinone. The composite showed a specific capacitance of 294 F/g at the scan rate of 10 mV/s, and could retain 95% of its initial specific capacitance after 1000 CV cycles. Such high electrochemical cycling stability resulting from the crosslinked skeleton of the C-CNTs makes them potential electrode materials for a supercapacitor. Full article

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

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Open AccessArticle

Plasmonics Meets Biology through Optics

by Luciano De Sio, Giulio Caracciolo, Ferdinanda Annesi, Tiziana Placido, Daniela Pozzi, Roberto Comparelli, Alfredo Pane, Maria Lucia Curri, Angela Agostiano and Roberto Bartolino

Nanomaterials 2015, 5(2), 1022-1033; https://doi.org/10.3390/nano5021022 - 09 Jun 2015

Cited by 1 | Viewed by 5472

Abstract

Plasmonic metallic nanoparticles (NPs) represent a relevant class of nanomaterials, which is able to achieve light localization down to nanoscale by exploiting a phenomenon called Localized Plasmon Resonance. In the last few years, NPs have been proposed to trigger DNA release or enhance [...] Read more.

Plasmonic metallic nanoparticles (NPs) represent a relevant class of nanomaterials, which is able to achieve light localization down to nanoscale by exploiting a phenomenon called Localized Plasmon Resonance. In the last few years, NPs have been proposed to trigger DNA release or enhance ablation of diseased tissues, while minimizing damage to healthy tissues. In view of the therapeutic relevance of such plasmonic NPs; a detailed characterization of the electrostatic interaction between positively charged gold nanorods (GNRs) and a negatively charged whole-genome DNA solution is reported. The preparation of the hybrid biosystem has been investigated as a function of DNA concentration by means of ζ-potential; hydrodynamic diameter and gel electrophoresis analysis. The results have pointed out the specific conditions to achieve the most promising GNRs/DNA complex and its photo-thermal properties have been investigated. The overall study allows to envisage the possibility to ingeniously combine plasmonic and biological materials and, thus, enable design and development of an original non invasive all-optical methodology for monitoring photo-induced temperature variation with high sensitivity. Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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2364 KiB

Open AccessReview

Antitumor Activities of Metal Oxide Nanoparticles

by Maria Pilar Vinardell and Montserrat Mitjans

Nanomaterials 2015, 5(2), 1004-1021; https://doi.org/10.3390/nano5021004 - 09 Jun 2015

Cited by 249 | Viewed by 12193

Abstract

Nanoparticles have received much attention recently due to their use in cancer therapy. Studies have shown that different metal oxide nanoparticles induce cytotoxicity in cancer cells, but not in normal cells. In some cases, such anticancer activity has been demonstrated to hold for [...] Read more.

Nanoparticles have received much attention recently due to their use in cancer therapy. Studies have shown that different metal oxide nanoparticles induce cytotoxicity in cancer cells, but not in normal cells. In some cases, such anticancer activity has been demonstrated to hold for the nanoparticle alone or in combination with different therapies, such as photocatalytic therapy or some anticancer drugs. Zinc oxide nanoparticles have been shown to have this activity alone or when loaded with an anticancer drug, such as doxorubicin. Other nanoparticles that show cytotoxic effects on cancer cells include cobalt oxide, iron oxide and copper oxide. The antitumor mechanism could work through the generation of reactive oxygen species or apoptosis and necrosis, among other possibilities. Here, we review the most significant antitumor results obtained with different metal oxide nanoparticles. Full article

(This article belongs to the Special Issue Advancements in Nanotoxicology)

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1963 KiB

Open AccessReview

Nano-Sized Cyclodextrin-Based Molecularly Imprinted Polymer Adsorbents for Perfluorinated Compounds—A Mini-Review

by Abdalla H. Karoyo and Lee D. Wilson

Nanomaterials 2015, 5(2), 981-1003; https://doi.org/10.3390/nano5020981 - 04 Jun 2015

Cited by 53 | Viewed by 8963

Abstract

Recent efforts have been directed towards the design of efficient and contaminant selective remediation technology for the removal of perfluorinated compounds (PFCs) from soils, sediments, and aquatic environments. While there is a general consensus on adsorption-based processes as the most suitable methodology for [...] Read more.

Recent efforts have been directed towards the design of efficient and contaminant selective remediation technology for the removal of perfluorinated compounds (PFCs) from soils, sediments, and aquatic environments. While there is a general consensus on adsorption-based processes as the most suitable methodology for the removal of PFCs from aquatic environments, challenges exist regarding the optimal materials design of sorbents for selective uptake of PFCs. This article reviews the sorptive uptake of PFCs using cyclodextrin (CD)-based polymer adsorbents with nano- to micron-sized structural attributes. The relationship between synthesis of adsorbent materials and their structure relate to the overall sorption properties. Hence, the adsorptive uptake properties of CD-based molecularly imprinted polymers (CD-MIPs) are reviewed and compared with conventional MIPs. Further comparison is made with non-imprinted polymers (NIPs) that are based on cross-linking of pre-polymer units such as chitosan with epichlorohydrin in the absence of a molecular template. In general, MIPs offer the advantage of selectivity, chemical tunability, high stability and mechanical strength, ease of regeneration, and overall lower cost compared to NIPs. In particular, CD-MIPs offer the added advantage of possessing multiple binding sites with unique physicochemical properties such as tunable surface properties and morphology that may vary considerably. This mini-review provides a rationale for the design of unique polymer adsorbent materials that employ an intrinsic porogen via incorporation of a macrocyclic compound in the polymer framework to afford adsorbent materials with tunable physicochemical properties and unique nanostructure properties. Full article

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Open AccessArticle

Kinetic Uptake Studies of Powdered Materials in Solution

by Mohamed H. Mohamed and Lee D. Wilson

Nanomaterials 2015, 5(2), 969-980; https://doi.org/10.3390/nano5020969 - 04 Jun 2015

Cited by 30 | Viewed by 5411

Abstract

Challenges exist for the study of time dependent sorption processes for heterogeneous systems, especially in the case of dispersed nanomaterials in solvents or solutions because they are not well suited to conventional batch kinetic experiments. In this study, a comparison of batch versus [...] Read more.

Challenges exist for the study of time dependent sorption processes for heterogeneous systems, especially in the case of dispersed nanomaterials in solvents or solutions because they are not well suited to conventional batch kinetic experiments. In this study, a comparison of batch versus a one-pot setup in two variable configurations was evaluated for the study of uptake kinetics in heterogeneous (solid/solution) systems: (i) conventional batch method; (ii) one-pot system with dispersed adsorbent in solution with a semi-permeable barrier (filter paper or dialysis tubing) for in situ sampling; and (iii) one-pot system with an adsorbent confined in a semi-permeable barrier (dialysis tubing or filter paper barrier) with ex situ sampling. The sorbent systems evaluated herein include several cyclodextrin-based polyurethane materials with two types of phenolic dyes: p-nitrophenol and phenolphthalein. The one-pot kinetics method with in situ (Method ii) or ex situ (Method iii) sampling described herein offers significant advantages for the study of heterogeneous sorption kinetics of highly dispersed sorbent materials with particles sizes across a range of dimensions from the micron to nanometer scale. The method described herein will contribute positively to the development of advanced studies for heterogeneous sorption processes where an assessment of the relative uptake properties is required at different experimental conditions. The results of this study will be advantageous for the study of nanomaterials with significant benefits over batch kinetic studies for a wide range of heterogeneous sorption processes. Full article

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1252 KiB

Open AccessReview

Synthesis of Helical Carbon Fibers and Related Materials: A Review on the Past and Recent Developments

by Himanshu Raghubanshi and Ezekiel Dixon Dikio

Nanomaterials 2015, 5(2), 937-968; https://doi.org/10.3390/nano5020937 - 02 Jun 2015

Cited by 18 | Viewed by 6493

Abstract

Helical carbon fibers (HCFs) have been widely studied due to their unique helical morphology and superior properties, which make them efficient materials for several potential applications. This review summarizes the past and current advancement on the synthesis of HCFs. The review focuses and [...] Read more.

Helical carbon fibers (HCFs) have been widely studied due to their unique helical morphology and superior properties, which make them efficient materials for several potential applications. This review summarizes the past and current advancement on the synthesis of HCFs. The review focuses and discusses synthesis strategies and effect of experimental parameters on the growth of HCFs. The effect of preparation method of catalyst, catalyst nature, catalyst composition, catalyst size, catalyst initial and final shape, reaction temperature, reaction time, carbon source, impurities, and electromagnetic field on the growth of HCFs is reviewed. We also discuss the growth mechanism for HCFs and the synthesis of HCFs related materials. Finally, we conclude with a brief summary and an outlook on the challenges and future prospects of HCFs. Full article

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Open AccessReview

Nanostructured Electrode Materials for Electrochemical Capacitor Applications

by Hojin Choi and Hyeonseok Yoon

Nanomaterials 2015, 5(2), 906-936; https://doi.org/10.3390/nano5020906 - 02 Jun 2015

Cited by 145 | Viewed by 13912

Abstract

The advent of novel organic and inorganic nanomaterials in recent years, particularly nanostructured carbons, conducting polymers, and metal oxides, has enabled the fabrication of various energy devices with enhanced performance. In this paper, we review in detail different nanomaterials used in the fabrication [...] Read more.

The advent of novel organic and inorganic nanomaterials in recent years, particularly nanostructured carbons, conducting polymers, and metal oxides, has enabled the fabrication of various energy devices with enhanced performance. In this paper, we review in detail different nanomaterials used in the fabrication of electrochemical capacitor electrodes and also give a brief overview of electric double-layer capacitors, pseudocapacitors, and hybrid capacitors. From a materials point of view, the latest trends in electrochemical capacitor research are also discussed through extensive analysis of the literature and by highlighting notable research examples (published mostly since 2013). Finally, a perspective on next-generation capacitor technology is also given, including the challenges that lie ahead. Full article

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

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Open AccessArticle

Emission Properties of Fluorescent Nanoparticles Determined by Their Optical Environment

by Kelvin Chung and Snjezana Tomljenovic-Hanic

Nanomaterials 2015, 5(2), 895-905; https://doi.org/10.3390/nano5020895 - 29 May 2015

Cited by 11 | Viewed by 4848

Abstract

The emission rate of a radiating dipole within a nanoparticle is crucially dependent on its surrounding refractive index environment. In this manuscript, we present numerical results on how the emission rates are affected for nanoparticles in a homogenous and substrate environment. These results [...] Read more.

The emission rate of a radiating dipole within a nanoparticle is crucially dependent on its surrounding refractive index environment. In this manuscript, we present numerical results on how the emission rates are affected for nanoparticles in a homogenous and substrate environment. These results are general, applicable to any refractive index distribution and emitter. Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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Open AccessArticle

Electronic Structure and Magnetism of Mn-Doped ZnO Nanowires

by Fuchun Zhang, Dandan Chao, Hongwei Cui, Weihu Zhang and Weibin Zhang

Nanomaterials 2015, 5(2), 885-894; https://doi.org/10.3390/nano5020885 - 27 May 2015

Cited by 18 | Viewed by 6105

Abstract

The geometric structures, electronic and magnetic properties of Mn-doped ZnO nanowires were investigated using density functional theory. The results indicated that all the calculated energy differences were negative, and the energy of the ground state was 0.229 eV lower than ferromagnetic coupling, which [...] Read more.

The geometric structures, electronic and magnetic properties of Mn-doped ZnO nanowires were investigated using density functional theory. The results indicated that all the calculated energy differences were negative, and the energy of the ground state was 0.229 eV lower than ferromagnetic coupling, which show higher stability in antiferromagnetic coupling. The calculated results indicated that obvious spin splitting phenomenon occurred near the Femi level. The Zn atoms on the inner layer of ZnO nanowires are easily substituted by Mn atoms along the [0001] direction. It was also shown that the Mn²⁺-O²⁻-Mn²⁺ magnetic coupling formed by intermediate O atom was proved to be caused by orbital hybridization between Mn 3d and O 2p states. The magnetic moments were mainly attributed to the unpaired Mn 3d orbitals, but not relevant with doping position of Mn atoms. Moreover, the optical properties of Mn-doped ZnO nanowires exhibited a novel blue-shifted optical absorption and enhanced ultraviolet-light emission. The above results show that the Mn-doped ZnO nanowires are a new type of magneto-optical materials with great promise. Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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Open AccessCommunication

Targeting of Apoptotic Cells Using Functionalized Fe₂O₃ Nanoparticles

by Moataz Mekawy, Atsushi Saito, Hiroaki Shimizu and Teiji Tominaga

Nanomaterials 2015, 5(2), 874-884; https://doi.org/10.3390/nano5020874 - 26 May 2015

Cited by 8 | Viewed by 5617

Abstract

Fe₂O₃ nanoparticles (NPs) have been synthesized and functionalized with SiO₂ and -NH₂ group, respectively. Conjugation to fluorescently-labeled poly-caspase inhibitor (SR-FLIVO) has been carried out for better cellular uptake studies of apoptosis arising from brain focal cerebral ischemia. Highest [...] Read more.

Fe₂O₃ nanoparticles (NPs) have been synthesized and functionalized with SiO₂ and -NH₂ group, respectively. Conjugation to fluorescently-labeled poly-caspase inhibitor (SR-FLIVO) has been carried out for better cellular uptake studies of apoptosis arising from brain focal cerebral ischemia. Highest conjugation affinity to SR-FLIVO was found to be ca. 80% for Fe₂O₃-SiO-NH₂ functionalized nanoparticles (FNPs). Tracking of SR-FLIVO conjugated functionalized nanoparticles (SR-FLIVO-FNPs) in vivo and in vitro has been carried out and detected using microscopic techniques after histochemical staining methods. Experimental results revealed that SR-FLIVO-FNPs probe could passively cross the blood brain barrier (BBB) and accumulated within the apoptotic cell. Optimization of SR-FLIVO-FNPs probe can effectively promise to open a new era for intracellular drug delivery and brain diagnosis. Full article

(This article belongs to the Special Issue Nanoparticles in Theranostics)

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365 KiB

Open AccessReview

Penetration and Toxicity of Nanomaterials in Higher Plants

by Giuseppe Chichiriccò and Anna Poma

Nanomaterials 2015, 5(2), 851-873; https://doi.org/10.3390/nano5020851 - 26 May 2015

Cited by 204 | Viewed by 14016

Abstract

Nanomaterials (NMs) comprise either inorganic particles consisting of metals, oxides, and salts that exist in nature and may be also produced in the laboratory, or organic particles originating only from the laboratory, having at least one dimension between 1 and 100 nm in [...] Read more.

Nanomaterials (NMs) comprise either inorganic particles consisting of metals, oxides, and salts that exist in nature and may be also produced in the laboratory, or organic particles originating only from the laboratory, having at least one dimension between 1 and 100 nm in size. According to shape, size, surface area, and charge, NMs have different mechanical, chemical, electrical, and optical properties that make them suitable for technological and biomedical applications and thus they are being increasingly produced and modified. Despite their beneficial potential, their use may be hazardous to health owing to the capacity to enter the animal and plant body and interact with cells. Studies on NMs involve technologists, biologists, physicists, chemists, and ecologists, so there are numerous reports that are significantly raising the level of knowledge, especially in the field of nanotechnology; however, many aspects concerning nanobiology remain undiscovered, including the interactions with plant biomolecules. In this review we examine current knowledge on the ways in which NMs penetrate plant organs and interact with cells, with the aim of shedding light on the reactivity of NMs and toxicity to plants. These points are discussed critically to adjust the balance with regard to the risk to the health of the plants as well as providing some suggestions for new studies on this topic. Full article

(This article belongs to the Special Issue Advancements in Nanotoxicology)

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Open AccessArticle

Toxicity and Biokinetics of Colloidal Gold Nanoparticles

by Mi-Rae Jo, Song-Hwa Bae, Mi-Ran Go, Hyun-Jin Kim, Yun-Gu Hwang and Soo-Jin Choi

Nanomaterials 2015, 5(2), 835-850; https://doi.org/10.3390/nano5020835 - 21 May 2015

Cited by 71 | Viewed by 7993

Abstract

Gold nanoparticles (Au-NPs) have promising potential for diverse biological application, but it has not been completely determined whether Au-NP has potential toxicity in vitro and in vivo. In the present study, toxicity of Au-NP was evaluated in human intestinal cells as well [...] Read more.

Gold nanoparticles (Au-NPs) have promising potential for diverse biological application, but it has not been completely determined whether Au-NP has potential toxicity in vitro and in vivo. In the present study, toxicity of Au-NP was evaluated in human intestinal cells as well as in rats after 14-day repeated oral administration. Biokinetic study was also performed to assess oral absorption and tissue distribution. The results demonstrated that Au-NP did not cause cytotoxic effects on cells after 24 h exposure in terms of inhibition of cell proliferation, membrane damage, and oxidative stress. However, when a small number of cells were exposed to Au-NP for seven days, colony forming ability remarkably decreased by Au-NP treatment, suggesting its potential toxicity after long-term exposure at high concentration. Biokinetic study revealed that Au-NP slowly entered the blood stream and slightly accumulated only in kidney after oral administration to rats. Whereas, orally administered Au ions were rapidly absorbed, and then distributed in kidney, liver, lung, and spleen at high levels, suggesting that the biological fate of Au-NP is primarily in nanoparticulate form, not in ionic Au. Fourteen-day repeated oral toxicity evaluation showed that Au-NP did not cause severe toxicity in rats based on histopathological, hematological, and serum biochemical analysis. Full article

(This article belongs to the Special Issue Advancements in Nanotoxicology)

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Open AccessArticle

Graphene Oxide Synthesis from Agro Waste

by Thirunavukkarasu Somanathan, Karthika Prasad, Kostya (Ken) Ostrikov, Arumugam Saravanan and Vemula Mohana Krishna

Nanomaterials 2015, 5(2), 826-834; https://doi.org/10.3390/nano5020826 - 20 May 2015

Cited by 166 | Viewed by 14539

Abstract

A new method of graphene oxide (GO) synthesis via single-step reforming of sugarcane bagasse agricultural waste by oxidation under muffled atmosphere conditions is reported. The strong and sharp X-ray diffraction peak at 2θ = 11.6° corresponds to an interlayer distance of 0.788 nm [...] Read more.

A new method of graphene oxide (GO) synthesis via single-step reforming of sugarcane bagasse agricultural waste by oxidation under muffled atmosphere conditions is reported. The strong and sharp X-ray diffraction peak at 2θ = 11.6° corresponds to an interlayer distance of 0.788 nm (d₀₀₂) for the AB stacked GOs. High-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) confirm the formation of the GO layer structure and the hexagonal framework. This is a promising method for fast and effective synthesis of GO from sugarcane bagasse intended for a variety of energy and environmental applications. Full article

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

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Open AccessArticle

Thermal Emission Control via Bandgap Engineering in Aperiodically Designed Nanophotonic Devices

by Enrique Maciá

Nanomaterials 2015, 5(2), 814-825; https://doi.org/10.3390/nano5020814 - 20 May 2015

Cited by 6 | Viewed by 4965

Abstract

Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their periodic counterparts. In this work [...] Read more.

Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their periodic counterparts. In this work we first describe the fundamental notions underlying the idea of thermal emission/absorption control on the basis of the systematic use of aperiodic multilayer designs in photonic quasicrystals. Then, we illustrate the potential applications of this approach in order to enhance the performance of daytime radiative coolers and solar thermoelectric energy generators. Full article

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

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Open AccessArticle

Phosphorothioate DNA Stabilized Fluorescent Gold and Silver Nanoclusters

by Daniel S. Weadick and Juewen Liu

Nanomaterials 2015, 5(2), 804-813; https://doi.org/10.3390/nano5020804 - 19 May 2015

Cited by 18 | Viewed by 7189

Abstract

Unmodified single-stranded DNA has recently gained popularity for the templated synthesis of fluorescent noble metal nanoclusters (NCs). Bright, stable, and biocompatible clusters have been developed primarily through optimization of DNA sequence. However, DNA backbone modifications have not yet been investigated. In this work, [...] Read more.

Unmodified single-stranded DNA has recently gained popularity for the templated synthesis of fluorescent noble metal nanoclusters (NCs). Bright, stable, and biocompatible clusters have been developed primarily through optimization of DNA sequence. However, DNA backbone modifications have not yet been investigated. In this work, phosphorothioate (PS) DNAs are evaluated in the synthesis of Au and Ag nanoclusters, and are employed to successfully template a novel emitter using T₁₅ DNA at neutral pH. Mechanistic studies indicate a distinct UV-dependent formation mechanism that does not occur through the previously reported thymine N3. The positions of PS substitution have been optimized. This is the first reported use of a T₁₅ template at physiological pH for AgNCs. Full article

(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)

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Open AccessArticle

Thermo-Optical Properties of Thin-Film TiO2–Al2O3 Bilayers Fabricated by Atomic Layer Deposition

by Rizwan Ali, Muhammad Rizwan Saleem, Pertti Pääkkönen and Seppo Honkanen

Nanomaterials 2015, 5(2), 792-803; https://doi.org/10.3390/nano5020792 - 18 May 2015

Cited by 20 | Viewed by 9162

Abstract

We investigate the optical and thermo-optical properties of amorphous TiO\(_2\)–Al\(_2\)O\(_3\) thin-film bilayers fabricated by atomic layer deposition (ALD). Seven samples of TiO\(_2\)–Al\(_2\)O\(_3\) bilayers are fabricated by growing Al\(_2\)O\(_3\) films of different thicknesses on the surface of TiO\(_2\) films of constant thickness (100 nm). [...] Read more.

We investigate the optical and thermo-optical properties of amorphous TiO\(_2\)–Al\(_2\)O\(_3\) thin-film bilayers fabricated by atomic layer deposition (ALD). Seven samples of TiO\(_2\)–Al\(_2\)O\(_3\) bilayers are fabricated by growing Al\(_2\)O\(_3\) films of different thicknesses on the surface of TiO\(_2\) films of constant thickness (100 nm). Temperature-induced changes in the optical refractive indices of these thin-film bilayers are measured by a variable angle spectroscopic ellipsometer VASE\textsuperscript{\textregistered}. The optical data and the thermo-optic coefficients of the films are retrieved and calculated by applying the Cauchy model and the linear fitting regression algorithm, in order to evaluate the surface porosity model of TiO\(_2\) films. The effects of TiO\(_2\) surface defects on the films' thermo-optic properties are reduced and modified by depositing ultra-thin ALD-Al\(_2\)O\(_3\) diffusion barrier layers. Increasing the ALD-Al\(_2\)O\(_3\) thickness from 20 nm to 30 nm results in a sign change of the thermo-optic coefficient of the ALD-TiO\(_2\). The thermo-optic coefficients of the 100 nm-thick ALD-TiO\(_2\) film and 30 nm-thick ALD-Al\(_2\)O\(_3\) film in a bilayer are (0.048 \(\pm\) 0.134) \(\times 10 ^{-4} {^\circ}\mathrm {C}^{-1}\) and (0.680 \(\pm\) 0.313) \(\times 10^{-4} {^\circ} \mathrm {C}^{-1}\), respectively, at a temperature \(T = 62 ^\circ \mathrm{C}\). Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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374 KiB

Open AccessArticle

Modeling the Dispersibility of Single Walled Carbon Nanotubes in Organic Solvents by Quantitative Structure-Activity Relationship Approach

by Hayriye Yilmaz, Bakhtiyor Rasulev and Jerzy Leszczynski

Nanomaterials 2015, 5(2), 778-791; https://doi.org/10.3390/nano5020778 - 12 May 2015

Cited by 17 | Viewed by 6148

Abstract

The knowledge of physico-chemical properties of carbon nanotubes, including behavior in organic solvents is very important for design, manufacturing and utilizing of their counterparts with improved properties. In the present study a quantitative structure-activity/property relationship (QSAR/QSPR) approach was applied to predict the dispersibility [...] Read more.

The knowledge of physico-chemical properties of carbon nanotubes, including behavior in organic solvents is very important for design, manufacturing and utilizing of their counterparts with improved properties. In the present study a quantitative structure-activity/property relationship (QSAR/QSPR) approach was applied to predict the dispersibility of single walled carbon nanotubes (SWNTs) in various organic solvents. A number of additive descriptors and quantum-chemical descriptors were calculated and utilized to build QSAR models. The best predictability is shown by a 4-variable model. The model showed statistically good results (R²_training = 0.797, Q² = 0.665, R²_test = 0.807), with high internal and external correlation coefficients. Presence of the X0Av descriptor and its negative term suggest that small size solvents have better SWCNTs solubility. Mass weighted descriptor ATS6m also indicates that heavier solvents (and small in size) most probably are better solvents for SWCNTs. The presence of the Dipole Z descriptor indicates that higher polarizability of the solvent molecule increases the solubility. The developed model and contributed descriptors can help to understand the mechanism of the dispersion process and predictorganic solvents that improve the dispersibility of SWNTs. Full article

(This article belongs to the Special Issue Advancements in Nanotoxicology)

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1788 KiB

Open AccessReview

Multifunctional Carbon Nanostructures for Advanced Energy Storage Applications

by Yiran Wang, Huige Wei, Yang Lu, Suying Wei, Evan K. Wujcik and Zhanhu Guo

Nanomaterials 2015, 5(2), 755-777; https://doi.org/10.3390/nano5020755 - 08 May 2015

Cited by 70 | Viewed by 10110

Abstract

Carbon nanostructures—including graphene, fullerenes, etc.—have found applications in a number of areas synergistically with a number of other materials. These multifunctional carbon nanostructures have recently attracted tremendous interest for energy storage applications due to their large aspect ratios, specific surface areas, and [...] Read more.

Carbon nanostructures—including graphene, fullerenes, etc.—have found applications in a number of areas synergistically with a number of other materials. These multifunctional carbon nanostructures have recently attracted tremendous interest for energy storage applications due to their large aspect ratios, specific surface areas, and electrical conductivity. This succinct review aims to report on the recent advances in energy storage applications involving these multifunctional carbon nanostructures. The advanced design and testing of multifunctional carbon nanostructures for energy storage applications—specifically, electrochemical capacitors, lithium ion batteries, and fuel cells—are emphasized with comprehensive examples. Full article

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

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617 KiB

Open AccessEditorial

Frontiers in Nucleic Acid Nanotechnology

by Stephen F. Ralph

Nanomaterials 2015, 5(2), 750-754; https://doi.org/10.3390/nano5020750 - 08 May 2015

Cited by 1 | Viewed by 4382

Abstract

This Special Issue of Nanomaterials highlights innovative work from around the world focused on harnessing the physical, chemical and topological properties of nucleic acids. [...] Full article

(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)

2723 KiB

Open AccessArticle

Synthesis, Characterization and Gas Sensing Properties of Ag@α-Fe₂O₃ Core–Shell Nanocomposites

by Ali Mirzaei, Kamal Janghorban, Babak Hashemi, Anna Bonavita, Maryam Bonyani, Salvatore Gianluca Leonardi and Giovanni Neri

Nanomaterials 2015, 5(2), 737-749; https://doi.org/10.3390/nano5020737 - 05 May 2015

Cited by 97 | Viewed by 8965

Abstract

Ag@α-Fe₂O₃ nanocomposite having a core–shell structure was synthesized by a two-step reduction-sol gel approach, including Ag nanoparticles synthesis by sodium borohydride as the reducing agent in a first step and the subsequent mixing with a Fe⁺³ sol for α-Fe [...] Read more.

Ag@α-Fe₂O₃ nanocomposite having a core–shell structure was synthesized by a two-step reduction-sol gel approach, including Ag nanoparticles synthesis by sodium borohydride as the reducing agent in a first step and the subsequent mixing with a Fe⁺³ sol for α-Fe₂O₃ coating. The synthesized Ag@α-Fe₂O₃ nanocomposite has been characterized by various techniques, such as SEM, TEM and UV-Vis spectroscopy. The electrical and gas sensing properties of the synthesized composite towards low concentrations of ethanol have been evaluated. The Ag@α-Fe₂O₃ nanocomposite showed better sensing characteristics than the pure α-Fe₂O₃. The peculiar hierarchical nano-architecture and the chemical and electronic sensitization effect of Ag nanoparticles in Ag@α-Fe₂O₃ sensors were postulated to play a key role in modulating gas-sensing properties in comparison to pristine α-Fe₂O₃ sensors. Full article

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2011 KiB

Open AccessArticle

Titration of DNA/Carbon Nanotube Complexes with Double-Chained Oppositely Charged Surfactants

by Franco Tardani and Camillo La Mesa

Nanomaterials 2015, 5(2), 722-736; https://doi.org/10.3390/nano5020722 - 30 Apr 2015

Cited by 5 | Viewed by 5964

Abstract

1/1 dispersions of ss-DNA/CNT complexes in mass ratios were investigated in a mixture with didodecyldimethylammonium bromide, DDAB. Depending on the amounts of the surface-active agent and of the complexes, solutions, precipitates, or re-dissolution occur. DDAB titrates the phosphate groups on the outer surface [...] Read more.

1/1 dispersions of ss-DNA/CNT complexes in mass ratios were investigated in a mixture with didodecyldimethylammonium bromide, DDAB. Depending on the amounts of the surface-active agent and of the complexes, solutions, precipitates, or re-dissolution occur. DDAB titrates the phosphate groups on the outer surface of the complex and controls the phase sequence in these systems. The combination of different experimental methods determined the phases that occur therein. The results are based on optical absorbance, Dynamic Light Scattering, ionic conductivity, ζ-potential, optical microscopy and AFM. From the above findings a (pseudo)-binary phase diagram is attained. The system has strong similarities with polymer-surfactant mixtures. In fact, its properties conform to cases in which interactions between rigid rod-like polyelectrolytes and oppositely charged species take place. The peculiarities of double-chained DDAB in the process imply significant differences with respect to the behavior of single chain surfactants. In fact, DDAB associates into vesicular entities, when the homologous single chain species forms small micellar aggregates. Full article

(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)

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5861 KiB

Open AccessReview

Dealloying of Cu-Based Metallic Glasses in Acidic Solutions: Products and Energy Storage Applications

by Zhifeng Wang, Jiangyun Liu, Chunling Qin, Hui Yu, Xingchuan Xia, Chaoyang Wang, Yanshan Zhang, Qingfeng Hu and Weimin Zhao

Nanomaterials 2015, 5(2), 697-721; https://doi.org/10.3390/nano5020697 - 29 Apr 2015

Cited by 29 | Viewed by 8499

Abstract

Dealloying, a famous ancient etching technique, was used to produce nanoporous metals decades ago. With the development of dealloying techniques and theories, various interesting dealloying products including nanoporous metals/alloys, metal oxides and composites, which exhibit excellent catalytic, optical and sensing performance, have been [...] Read more.

Dealloying, a famous ancient etching technique, was used to produce nanoporous metals decades ago. With the development of dealloying techniques and theories, various interesting dealloying products including nanoporous metals/alloys, metal oxides and composites, which exhibit excellent catalytic, optical and sensing performance, have been developed in recent years. As a result, the research on dealloying products is of great importance for developing new materials with superior physical and chemical properties. In this paper, typical dealloying products from Cu-based metallic glasses after dealloying in hydrofluoric acid and hydrochloric acid solutions are summarized. Several potential application fields of these dealloying products are discussed. A promising application of nanoporous Cu (NPC) and NPC-contained composites related to the energy storage field is introduced. It is expected that more promising dealloying products could be developed for practical energy storage applications. Full article

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

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3958 KiB

Open AccessReview

Structural Ceramic Nanocomposites: A Review of Properties and Powders’ Synthesis Methods

by Paola Palmero

Nanomaterials 2015, 5(2), 656-696; https://doi.org/10.3390/nano5020656 - 28 Apr 2015

Cited by 222 | Viewed by 17626

Abstract

Ceramic nanocomposites are attracting growing interest, thanks to new processing methods enabling these materials to go from the research laboratory scale to the commercial level. Today, many different types of nanocomposite structures are proposed in the literature; however, to fully exploit their exceptional [...] Read more.

Ceramic nanocomposites are attracting growing interest, thanks to new processing methods enabling these materials to go from the research laboratory scale to the commercial level. Today, many different types of nanocomposite structures are proposed in the literature; however, to fully exploit their exceptional properties, a deep understanding of the materials’ behavior across length scales is necessary. In fact, knowing how the nanoscale structure influences the bulk properties enables the design of increasingly performing composite materials. A further key point is the ability of tailoring the desired nanostructured features in the sintered composites, a challenging issue requiring a careful control of all stages of manufacturing, from powder synthesis to sintering. This review is divided into four parts. In the first, classification and general issues of nanostructured ceramics are reported. The second provides basic structure–property relations, highlighting the grain-size dependence of the materials properties. The third describes the role of nanocrystalline second-phases on the mechanical properties of ordinary grain sized ceramics. Finally, the fourth part revises the mainly used synthesis routes to produce nanocomposite ceramic powders, underlining when possible the critical role of the synthesis method on the control of microstructure and properties of the sintered ceramics. Full article

(This article belongs to the Special Issue Ceramic Nanocomposites: Design Concepts towards Tailor-Made (Multi)Functionality and Prospective Energy-Related Applications)

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4922 KiB

Open AccessReview

Optical and Structural Properties of Si Nanocrystals in SiO2 Films

by Timur Nikitin and Leonid Khriachtchev

Nanomaterials 2015, 5(2), 614-655; https://doi.org/10.3390/nano5020614 - 22 Apr 2015

Cited by 42 | Viewed by 8981

Abstract

Optical and structural properties of Si nanocrystals (Si-nc) in silica films are described. For the SiOx (x < 2) films annealed above 1000 °C, the Raman signal of Si-nc and the absorption coefficient are proportional to the amount of elemental Si detected by [...] Read more.

Optical and structural properties of Si nanocrystals (Si-nc) in silica films are described. For the SiOx (x < 2) films annealed above 1000 °C, the Raman signal of Si-nc and the absorption coefficient are proportional to the amount of elemental Si detected by X-ray photoelectron spectroscopy. A good agreement is found between the measured refractive index and the value estimated by using the effective-medium approximation. The extinction coefficient of elemental Si is found to be between the values of crystalline and amorphous Si. Thermal annealing increases the degree of Si crystallization; however, the crystallization and the Si–SiO2 phase separation are not complete after annealing at 1200 °C. The 1.5-eV PL quantum yield increases as the amount of elemental Si decreases; thus, this PL is probably not directly from Si-nc responsible for absorption and detected by Raman spectroscopy. Continuous-wave laser light can produce very high temperatures in the free-standing films, which changes their structural and optical properties. For relatively large laser spots, the center of the laser-annealed area is very transparent and consists of amorphous SiO2. Large Si-nc (up to ∼300 nm in diameter) are observed in the ring around the central region. These Si-nc lead to high absorption and they are typically under compressive stress, which is connected with their formation from the liquid phase. By using strongly focused laser beams, the structural changes in the free-standing films can be made in submicron areas. Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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1992 KiB

Open AccessReview

Magneto-Plasmonics and Resonant Interaction of Light with Dynamic Magnetisation in Metallic and All-Magneto-Dielectric Nanostructures

by Ivan S. Maksymov

Nanomaterials 2015, 5(2), 577-613; https://doi.org/10.3390/nano5020577 - 09 Apr 2015

Cited by 80 | Viewed by 10963

Abstract

A significant interest in combining plasmonics and magnetism at the nanoscale gains momentum in both photonics and magnetism sectors that are concerned with the resonant enhancement of light-magnetic-matter interaction in nanostructures. These efforts result in a considerable amount of literature, which is difficult [...] Read more.

A significant interest in combining plasmonics and magnetism at the nanoscale gains momentum in both photonics and magnetism sectors that are concerned with the resonant enhancement of light-magnetic-matter interaction in nanostructures. These efforts result in a considerable amount of literature, which is difficult to collect and digest in limited time. Furthermore, there is insufficient exchange of results between the two research sectors. Consequently, the goal of this review paper is to bridge this gap by presenting an overview of recent progress in the field of magneto-plasmonics from two different points of view: magneto-plasmonics, and magnonics and magnetisation dynamics. It is expected that this presentation style will make this review paper of particular interest to both general physical audience and specialists conducting research on photonics, plasmonics, Brillouin light scattering spectroscopy of magnetic nanostructures and magneto-optical Kerr effect magnetometry, as well as ultrafast all-optical and THz-wave excitation of spin waves. Moreover, readers interested in a new, rapidly emerging field of all-dielectric nanophotonics will find a section about all-magneto-dielectric nanostructures. Full article

(This article belongs to the Special Issue Nanophotonic Materials)

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Nanomaterials, Volume 5, Issue 2 (June 2015) – 39 articles , Pages 386-1135

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