Materials

2088 KiB

Open AccessArticle

Detection of the Presence of Gold Nanoparticles in Organs by Transmission Electron Microscopy

by Wim H. De Jong, Marina C. Burger, Marcel A. Verheijen and Robert E. Geertsma

Materials 2010, 3(9), 4681-4694; https://doi.org/10.3390/ma3094681 - 27 Sep 2010

Cited by 35 | Viewed by 11606

Gold nanoparticles of 10 nm and 250 nm were intravenously injected in rats. At 24 h after administration, tissues were collected and prepared for transmission electron microscopy (TEM). In the liver and spleen of animals treated with 10 nm gold nanoparticles, groups of [...] Read more.

Gold nanoparticles of 10 nm and 250 nm were intravenously injected in rats. At 24 h after administration, tissues were collected and prepared for transmission electron microscopy (TEM). In the liver and spleen of animals treated with 10 nm gold nanoparticles, groups of nanoparticles were observed that could be positively identified by Energy Dispersive X-ray (EDX) analysis to contain gold, while nanoparticles could not be detected in the heart, kidney and brain. The 10 nm gold nanoparticles were present in the phagocytic cells of the reticulo-endothelial system (RES). The 250 nm gold nanoparticles could not be detected in any of the organs investigated. Considering the number of 250 nm gold nanoparticles administered, calculations showed that it would indeed be almost impossible to detect the 250 nm gold nanoparticles in TEM preparations in view of the very low number of particles that would be theoretically present in one TEM tissue section. This shows that relatively high numbers of nanoparticles need to be administered to enable the detection of nanoparticles in organs by TEM. In a number of samples, several globular structures of approximately the expected size were found in liver cells and the endothelium of blood vessels in the brain. However, elemental analysis with EDX detection showed that these structures did not contain gold. Our studies thus indicate that the in vivo identification of nanoparticles cannot only depend on the detection of nanosized structures in cells. An additional identification of the composing elements of the nanomaterial is necessary for a positive identification of the nanomaterial. Full article

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481 KiB

Open AccessArticle

Frictional Behavior of Individual Vascular Smooth Muscle Cells Assessed By Lateral Force Microscopy

by Delphine Dean, Jason Hemmer, Alexey Vertegel and Martine LaBerge

Materials 2010, 3(9), 4668-4680; https://doi.org/10.3390/ma3094668 - 14 Sep 2010

Cited by 12 | Viewed by 9164

Abstract

With the advancement of the field of biotribology, considerable interest has arisen in the study of cell and tissue frictional properties. From the perspective of medical device development, the frictional properties between a rigid surface and underlying cells and tissues are of a [...] Read more.

With the advancement of the field of biotribology, considerable interest has arisen in the study of cell and tissue frictional properties. From the perspective of medical device development, the frictional properties between a rigid surface and underlying cells and tissues are of a particular clinical interest. As with many bearing surfaces, it is likely that contact asperities exist at the size scale of single cells and below. Thus, a technique to measure cellular frictional properties directly would be beneficial from both a clinical and a basic science perspective. In the current study, an atomic force microscope (AFM) with a 5 µm diameter borosilicate spherical probe simulating endovascular metallic stent asperities was used to characterize the surface frictional properties of vascular smooth muscle cells (VSMCs) in contact with a metallic endovascular stent. Various treatments were used to alter cell structure, in order to better understand the cellular components and mechanisms responsible for governing frictional properties. The frictional coefficient of the probe on VSMCs was found to be approximately 0.06. This frictional coefficient was significantly affected by cellular crosslinking and cytoskeletal depolymerization agents. These results demonstrate that AFM-based lateral force microscopy is a valuable technique to assess the friction properties of individual single cells on the micro-scale. Full article

(This article belongs to the Special Issue SPM in Materials Science)

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481 KiB

Open AccessArticle

Growth and Structure of ZnO Nanorods on a Sub-Micrometer Glass Pipette and Their Application as Intracellular Potentiometric Selective Ion Sensors

by Muhammad H. Asif, Omer Nur, Magnus Willander, Peter Strålfors, Cecilia Brännmark, Fredrik Elinder, Ulrika H. Englund, Jun Lu and Lars Hultman

Materials 2010, 3(9), 4657-4667; https://doi.org/10.3390/ma3094657 - 9 Sep 2010

Cited by 22 | Viewed by 10790

Abstract

This paper presents the growth and structure of ZnO nanorods on a sub-micrometer glass pipette and their application as an intracellular selective ion sensor. Highly oriented, vertical and aligned ZnO nanorods were grown on the tip of a borosilicate glass capillary (0.7 µm [...] Read more.

This paper presents the growth and structure of ZnO nanorods on a sub-micrometer glass pipette and their application as an intracellular selective ion sensor. Highly oriented, vertical and aligned ZnO nanorods were grown on the tip of a borosilicate glass capillary (0.7 µm in diameter) by the low temperature aqueous chemical growth (ACG) technique. The relatively large surface-to-volume ratio of ZnO nanorods makes them attractive for electrochemical sensing. Transmission electron microscopy studies show that ZnO nanorods are single crystals and grow along the crystal’s c-axis. The ZnO nanorods were functionalized with a polymeric membrane for selective intracellular measurements of Na⁺. The membrane-coated ZnO nanorods exhibited a Na⁺-dependent electrochemical potential difference versus an Ag/AgCl reference micro-electrode within a wide concentration range from 0.5 mM to 100 mM. The fabrication of functionalized ZnO nanorods paves the way to sense a wide range of biochemical species at the intracellular level. Full article

(This article belongs to the Special Issue Bio-devices and Materials)

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1012 KiB

Open AccessReview

Fabrication of Al-Al₃Ti/Ti₃Al Functionally Graded Materials under a Centrifugal Force

by Shimaa El-Hadad, Hisashi Sato, Eri Miura-Fujiwara and Yoshimi Watanabe

Materials 2010, 3(9), 4639-4656; https://doi.org/10.3390/ma3094639 - 8 Sep 2010

Cited by 37 | Viewed by 11343

Abstract

Fabrication of Al-Al₃Ti functionally graded materials (FGMs) under the centrifugal force has recently attracted some attention. The controlled compositional gradient of the fabricated FGMs, the low cost of the process, and the good mold filling, are the main advantages of the [...] Read more.

Fabrication of Al-Al₃Ti functionally graded materials (FGMs) under the centrifugal force has recently attracted some attention. The controlled compositional gradient of the fabricated FGMs, the low cost of the process, and the good mold filling, are the main advantages of the centrifugal method (CM). Using the conventional CM techniques such as the centrifugal solid-particle method and centrifugal in-situ method, FGMs rings with gradually distributed properties could be achieved. As a more practical choice, the centrifugal mixed-powder method (CMPM) was recently proposed to obtain FGMs containing nano-particles selectively dispersed in the outer surface of the fabricated parts. However, if a control of the particles morphology, compound formulas or sizes, is desired, another CM technique is favored. As a development of CMPM, our novel reaction centrifugal mixed-powder method (RCMPM) has been presented. Using RCMPM, Al‑Al₃Ti/Ti₃Al FGMs with good surface properties and temperature controlled compositional gradient could be achieved. In this short review, this novel method will be discussed in detail and the effect of RCMPM processing temperature on the reinforcement particles morphology, size and distribution through the fabricated samples, will be reviewed. Full article

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528 KiB

Open AccessReview

Copper Nanoparticles for Printed Electronics: Routes Towards Achieving Oxidation Stability

by Shlomo Magdassi, Michael Grouchko and Alexander Kamyshny

Materials 2010, 3(9), 4626-4638; https://doi.org/10.3390/ma3094626 - 8 Sep 2010

Cited by 375 | Viewed by 28343

Abstract

In the past few years, the synthesis of Cu nanoparticles has attracted much attention because of its huge potential for replacing expensive nano silver inks utilized in conductive printing. A major problem in utilizing these copper nanoparticles is their inherent tendency to oxidize [...] Read more.

In the past few years, the synthesis of Cu nanoparticles has attracted much attention because of its huge potential for replacing expensive nano silver inks utilized in conductive printing. A major problem in utilizing these copper nanoparticles is their inherent tendency to oxidize in ambient conditions. Recently, there have been several reports presenting various approaches which demonstrate that copper nanoparticles can resist oxidation under ambient conditions, if they are coated by a proper protective layer. This layer may consist of an organic polymer, alkene chains, amorphous carbon or graphenes, or inorganic materials such as silica, or an inert metal. Such coated copper nanoparticles enable achieving high conductivities by direct printing of conductive patterns. These approaches open new possibilities in printed electronics, for example by using copper based inkjet inks to form various devices such as solar cells, Radio Frequency Identification (RFID) tags, and electroluminescence devices. This paper provides a review on the synthesis of copper nanoparticles, mainly by wet chemistry routes, and their utilization in printed electronics. Full article

(This article belongs to the Special Issue Metal Nanoparticles)

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912 KiB

Open AccessReview

Creating Surface Properties Using a Palette of Hydrophobins

by Filippo Zampieri, Han A. B. Wösten and Karin Scholtmeijer

Materials 2010, 3(9), 4607-4625; https://doi.org/10.3390/ma3094607 - 6 Sep 2010

Cited by 41 | Viewed by 13203

Abstract

Small secreted proteins called hydrophobins play diverse roles in the life cycle of filamentous fungi. For example, the hydrophobin SC3 of Schizophyllum commune is involved in aerial hyphae formation, cell-wall assembly and attachment to hydrophobic surfaces. Hydrophobins are capable of self-assembly at a [...] Read more.

Small secreted proteins called hydrophobins play diverse roles in the life cycle of filamentous fungi. For example, the hydrophobin SC3 of Schizophyllum commune is involved in aerial hyphae formation, cell-wall assembly and attachment to hydrophobic surfaces. Hydrophobins are capable of self-assembly at a hydrophilic-hydrophobic interface, resulting in the formation of an amphipathic film. This amphipathic film can make hydrophobic surfaces of a liquid or a solid material wettable, while a hydrophilic surface can be turned into a hydrophobic one. These properties, among others, make hydrophobins of interest for medical and technical applications. For instance, hydrophobins can be used to purify proteins from complex mixtures; to reduce the friction of materials; to increase the biocompatibility of medical implants; to increase the solubility of water insoluble drugs; and to immobilize enzymes, for example, biosensor surfaces. Full article

(This article belongs to the Special Issue Advances in Surface Coatings)

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832 KiB

Open AccessReview

The Utility of Nanocomposites in Fire Retardancy

by Linjiang Wang, Xuejun He and Charles A. Wilkie

Materials 2010, 3(9), 4580-4606; https://doi.org/10.3390/ma3094580 - 3 Sep 2010

Cited by 73 | Viewed by 10872

Abstract

Nanocomposites have been shown to significantly reduce the peak heat release rate, as measured by cone calorimetry, for many polymers but they typically have no effect on the oxygen index or the UL-94 classification. In this review, we will cover what is known [...] Read more.

Nanocomposites have been shown to significantly reduce the peak heat release rate, as measured by cone calorimetry, for many polymers but they typically have no effect on the oxygen index or the UL-94 classification. In this review, we will cover what is known about the processes by which nanocomposite formation may bring this about. Montmorillonite will be the focus in this paper but attention will also be devoted to other materials, including carbon nanotubes and layered double hydroxides. A second section will be devoted to combinations of nanocomposite formation with conventional (and unconventional) fire retardants. The paper will conclude with a section attempting to forecast the future. Full article

(This article belongs to the Special Issue Flame Retardants)

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1540 KiB

Open AccessReview

The Electronic Structure and Secondary Pyroelectric Properties of Lithium Tetraborate

by Volodymyr.T. Adamiv, Yaroslav.V. Burak, David. J. Wooten, John McClory, James Petrosky, Ihor Ketsman, Jie Xiao, Yaroslav B. Losovyj and Peter A. Dowben

Materials 2010, 3(9), 4550-4579; https://doi.org/10.3390/ma3094550 - 1 Sep 2010

Cited by 25 | Viewed by 10205

Abstract

We review the pyroelectric properties and electronic structure of Li₂B₄O₇(110) and Li₂B₄O₇(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li₂B₄O [...] Read more.

We review the pyroelectric properties and electronic structure of Li₂B₄O₇(110) and Li₂B₄O₇(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li₂B₄O₇ so that the pyroelectric coefficient is nonzero but roughly 10³ smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of a tensor, as expected. The time dependent surface photovoltaic charging suggests that surface charging is dependent on crystal orientation and doping, as well as temperature. Full article

(This article belongs to the Special Issue Advances in Ferroelectric & Piezoelectric Materials)

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3725 KiB

Open AccessReview

Surface Nano-Structuring by Adsorption and Chemical Reactions

by Ken-ichi Tanaka

Materials 2010, 3(9), 4518-4549; https://doi.org/10.3390/ma3094518 - 27 Aug 2010

Cited by 14 | Viewed by 10465

Abstract

Nano-structuring of the surface caused by adsorption of molecules or atoms and by the reaction of surface atoms with adsorbed species are reviewed from a chemistry viewpoint. Self-assembly of adsorbed species is markedly influenced by weak mutual interactions and the local strain of [...] Read more.

Nano-structuring of the surface caused by adsorption of molecules or atoms and by the reaction of surface atoms with adsorbed species are reviewed from a chemistry viewpoint. Self-assembly of adsorbed species is markedly influenced by weak mutual interactions and the local strain of the surface induced by the adsorption. Nano-structuring taking place on the surface is well explained by the notion of a quasi-molecule provided by the reaction of surface atoms with adsorbed species. Self-assembly of quasi-molecules by weak internal bonding provides quasi-compounds on a specific surface. Various nano-structuring phenomena are discussed: (i) self-assembly of adsorbed molecules and atoms; (ii) self-assembly of quasi-compounds; (iii) formation of nano-composite surfaces; (iv) controlled growth of nano-materials on composite surfaces. Nano-structuring processes are not always controlled by energetic feasibility, that is, the formation of nano-composite surface and the growth of nano-particles on surfaces are often controlled by the kinetics. The idea of the “kinetic controlled molding” might be valuable to design nano-materials on surfaces. Full article

(This article belongs to the Special Issue SPM in Materials Science)

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510 KiB

Open AccessArticle

C₆₀ Intercalated Graphite as Nanolubricants

by Kouji Miura and Makoto Ishikawa

Materials 2010, 3(9), 4510-4517; https://doi.org/10.3390/ma3094510 - 27 Aug 2010

Cited by 18 | Viewed by 8172

Abstract

We synthesized the novel nanocomposite consisting of alternately stacked single graphene sheets and a C₆₀ monolayer by using the graphite intercalation technique in which alkylamine molecules help intercalate large C₆₀ molecules into the graphite. It is found that the intercalated C [...] Read more.

We synthesized the novel nanocomposite consisting of alternately stacked single graphene sheets and a C₆₀ monolayer by using the graphite intercalation technique in which alkylamine molecules help intercalate large C₆₀ molecules into the graphite. It is found that the intercalated C₆₀ molecules can rotate in between single graphene sheets by using ¹³C NMR measurements. The grease with the nanocomposite materials provides a much better lubricating performance than that with other additives that have been well-known up to now. This result exhibits that a C₆₀monolayer intercalated between graphenes plays an important role in lubricating behavior. Full article

(This article belongs to the Special Issue Lubricants)

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Materials, Volume 3, Issue 9 (September 2010) – 10 articles , Pages 4510-4694

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