Most recent issue published online for the International Journal of Nanotechnology.

Editorial: Nanoscience and Nanotechnology in Provence-Alpes-Côte d'Azur

2012-02-06T23:20:50-05:00

Editorial: Nanoscience and Nanotechnology in Provence-Alpes-Côte d'Azur
Margrit Hanbücken; Michel Lannoo; Wilfried Blanc; Thierry Djenizian; Lionel Santinacci
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 163 - 166
An overview over activities in nanoscience and nanotechnology in France and specifically the Provence-Alpes-Côte d'Azur Region is given. Nanoscience activities are organised and funded in France by several institutions. A dedicated national programme, called C'Nano and which is coordinated by the French National Center for Scientific Research – CNRS, assures the animation. Project funding comes on the national level from the French Ministry for Higher Education and the French National Research Agency (ANR) or regionally from Universities and Regional and Local Councils. The activities and initiatives in nanoscience are accompanied by dedicated teaching and educational programmes.

Environmental fate of nanoparticles: physical chemical and biological aspects – a few snapshots

2012-02-06T23:20:50-05:00

Environmental fate of nanoparticles: physical chemical and biological aspects – a few snapshots
Armand Masion; Mélanie Auffan; Jérôme Labille; Céline Botta; Natalia Solovitch; Jérôme Rose; Jean-Yves Bottero
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 167 - 180
The environmental risk that nanomaterials can undergo is a major problem, which could prevent the commercial development of nanoproducts, especially in technology domains corresponding to large distribution: cosmetics, composite materials, civil engineering materials and leisure materials. The risk assessment is based on a complex approach, which implies the knowledge of the degradation mechanisms of the nanoproducts in aquatic media (kinetics and chemical change), the quantities that are distributed in the different ecosystem compartments and the biological effects on various targets (bacterial micro-organisms, primary and secondary predators). The paper aims at showing the unique surface properties of nanomaterials and especially when the size is decreasing largely less than 100 nm, the stability and the eventual degradation of intermediate nanomaterials, e.g., some composites used in sunscreens. The biological effects of the nanomaterials depends on their unique properties and especially the large surface tension as the size decreases, the defects within the bulk and on the surface at the origin of the production of ROS. The molecular mechanisms underlying the toxicity are described especially in terms of oxidation-reduction reactions owing to surface reactivity, surface atoms dissolution, oxidative dissolution and dissolution.

Effects of metallic and metal oxide nanoparticles in aquatic and terrestrial food chains. Biomarkers responses in invertebrates and bacteria

2012-02-06T23:20:50-05:00

Effects of metallic and metal oxide nanoparticles in aquatic and terrestrial food chains. Biomarkers responses in invertebrates and bacteria
A. Thiéry; L. De Jong; J. Issartel; X. Moreau; G. Saez; P. Barthélémy; I. Bestel; C. Santaella; W. Achouak; M. Auffan; J. Rose; J-Y. Bottero
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 181 - 203
Although the market of nanoparticles (NPs) is rapidly expanding, the environmental and health impact of manufactured NPs and nanomaterials is still poorly understood and predictable. Hence, several laboratories of the PACA region have unified their skills to address this issue with an interdisciplinary approach. We present an outline of the ecological impact of metallic and metal oxide NPs span from the surface atoms of NPs, to unicellular organisms, such as bacteria, and organism levels. On multicellular organisms, we focus on biomarkers reporting on stress, central nervous system endpoints and antioxidative balance assessment. On bacteria, which are key players in NPs transfer, we study not only the impact of NPs on cells, at the microbial community, cell and molecular level, but also the effect of cells on NPs. Our priority is through our collaborations, to surpass case-by-case studies and develop aquatic and terrestrial mesocosms, to get information at an integrative level on the trophic links and ecosystemic consequences of NPs.

Adsorption of nickel and arsenic from aqueous solution on natural sepiolite

S. Ansanay-Alex; C. Lomenech; C. Hurel; N. Marmier — 2012-02-06T23:20:50-05:00

Adsorption of nickel and arsenic from aqueous solution on natural sepiolite
S. Ansanay-Alex; C. Lomenech; C. Hurel; N. Marmier
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 204 - 215
The adsorption capacity of a natural nanostructured clay (sepiolite) for the inorganic species: Ni2+ and As(V) has been studied using a batch method. The different parameters affecting sorption such as the mass of adsorbent, contact time, sorbate concentration or pH have been investigated and optimal experimental conditions have been determined. Langmuir and Freundlich equations, which are commonly used to describe sorption equilibrium, were applied to model experimental results. The maximum sorption capacity of sepiolite towards Ni2+ and As(V) was 2.236 mg g−1 and 0.006 mg g−1, respectively. The differences between the sorption capacities could be explained by different parameters like the charge of the ions or the free energy of hydration. The conclusion of this study is that natural sepiolite can adsorb cationic heavy metal and anionic metalloid species, which can have interesting applications in environmental applications such as the removal of these species from polluted waters.

Functionalisation through periodically arranged nanostructures

2012-02-06T23:20:50-05:00

Functionalisation through periodically arranged nanostructures
Houda Sahaf; Eric Moyen; Magali Macé; Laurence Masson; Margrit Hanbücken; Lukas Gerhard; Wulf Wulfhekel
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 216 - 229
The controlled fabrication of uniform nanostructure arrays and their subsequent use for selective functionalisations of substrates is of increasing interest for controlled applications in nanotechnology. Fabrication of nanostructures via epitaxial growth has turned out to be an interesting alternative to standard lithography methods. In this work, we present the elaboration and fabrication of ordered, regular arrays of identical nanostructures, arranged in either one or two dimensions, obtained through different experimental bottom-up and top-down approaches. These nanostructures can be grown in different sizes and various shapes like nanoparticles, nanodiscs or nanostripes. One-dimensional nanostructure arrangements are obtained through the controlled growth on previously nanopatterned templates like vicinal Si(111) substrates or structured Ag(110) surfaces. Two-dimensional nanostructure arrangements are obtained by deposition of the adsorbate material through the openings of a nanoporous alumina membrane, serving in this case as an evaporation mask. A local functionalisation of substrates can be obtained in specific cases like growth of magnetic material on silicon or catalytic matter and graphene on silicon carbide and will be described.

Laser-ablative nanostructuring of surfaces

2012-02-06T23:20:50-05:00

Laser-ablative nanostructuring of surfaces
A.V. Kabashin; T. Sarnet; D. Grojo; Ph. Delaporte; L. Charmasson; P. Blandin; R. Torres; T.J-Y. Derrien; M. Sentis
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 230 - 245
We present an overview of laser methods for nanostructuring of surfaces that are in the focus of ongoing research activities of our Institute (LP3). The methods imply the removal of material by laser radiation to provide either spontaneous nanostructuring of laser-illuminated surface or its controlled nano-modification. Here, the desired relief or architecture is achieved through a proper selection of radiation characteristics (pulse duration and wavelength) and parameters of environment (pressure of ambient gas, etc.). Examples of formed nano-architectures include penguin-like structures of black Si with enhanced light absorption in the visible, semiconductor (Si, Ge, ZnO, etc.) quantum dot nanostructures with UV/visible fluorescence, as well as periodic plasmonic nanoarrays. Exhibiting a series of unique properties, these structures are of importance for photovoltaics, optoelectronics and biological sensing applications.

Anodic 3D nanostructuring for tailored applications

2012-02-06T23:20:50-05:00

Anodic 3D nanostructuring for tailored applications
Eric Moyen; Lionel Santinacci; Laurence Masson; Houda Sahaf; Magali Macé; Loïc Assaud; Margrit Hanbücken
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 246 - 259
Electrochemistry can be used to fabricate different three dimensional objects on the nanometre scale. Porous anodic aluminium oxide (AAO) membranes with varying but controlled morphologies are used in several complementary experiments in physics and biology. The present paper gives a description of the membrane fabrication procedure and presents a selection of applications based on the use of the membranes as evaporation masks in crystal growth experiments, as masks in reactive ion etching experiments or as moulds to fabricate arrays of ordered polymer nanopillars. Applications in energy storage are also briefly mentioned. Finally the fabrication of TiO2 nanotubes (TNT) is described. Their anodic formation is very close to that of the AAO membranes and TNTs offer additional perspectives for applications.

Novel fabrication technologies of 1D TiO2 nanotubes, vertical tin and iron-based nanowires for Li-ion microbatteries

2012-02-06T23:20:50-05:00

Novel fabrication technologies of 1D TiO2 nanotubes, vertical tin and iron-based nanowires for Li-ion microbatteries
Gregorio F. Ortiz; Ilie Hanzu; Pedro Lavela; Philippe Knauth; Thierry Djenizian; José L. Tirado
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 260 - 294
We present the combination of anodisation, sputtering and electrodeposition processes as a novel technology to fabricate nanoarchitectured materials. Titania nanotubes are successfully fabricated using Ti foils and Ti film on Si wafers; by simply varying the anodisation parameters a 600-900 nm range of tube length and a 50-150 nm range of tube diameter can be obtained. Iron and tin oxides nanowires, microballs, microcubes or with sponge-like morphology are obtained showing that the crystallinity can be tuned by optional heat treatment, but the initial morphology is preserved. We investigate all these materials as alternative electrodes for lithium-ion batteries and microbatteries. It should be highlighted the fabrication of vertical nanowires using a template-free approach exhibits some advantages because the electroactive species are fabricated directly onto the current collector, ensuring good electrical contact between titania nanotube layers and the current collector, and tackle the use of additives such as binder and conductive agents. Thus, Sn on an amorphous titania matrix and SnO nanowires on a crystalline titania matrix with a particular geometry (2 µm of tin/tin oxide length) have a remarkable reversible capacity of about 140 µA h cm−2 (675 mA h g−1 and 70 µA h cm−2 µm−1) which is kept about 85% over 50 cycles. The matrix presented here can allow the volume expansion of lithium-tin alloys and thus enhances the electrochemical performances as compared with usual tin-based electrodes. In the text is also described the electrochemistry of a series of samples such as a 3 µm thick nanocomposite made of vertical iron oxide nanowires with quite regular form and diameters ranging between 20 nm and 150 nm grown on a matrix of self-organised TiO2 nanotubes. The obtained capacities compare very favourably with the best literature data for Li-ion microbatteries.

Electrochemical fabrication of oriented ZnO nanorods on TiO2 nanotubes

2012-02-06T23:20:50-05:00

Electrochemical fabrication of oriented ZnO nanorods on TiO2 nanotubes
Marielle Eyraud; G. Jimenez-Cadena; C. Chassigneux; F. Vacandio; E. Comini; G. Sberveglieri; T. Djenizian
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 295 - 311
We report the ability to use TiO2 nanotube as a guide layer to achieve the vertical growth of ZnO nanorods, in additive-free bath. First, we focused on the anodisation conditions (cell voltage and anodisation time) to produce TiO2 nanotube thin films grown from a 1.5 µm thick Ti layer sputtered onto Si. Highly organised titania nanotubes were obtained in glycerol viscous electrolyte. In a second step, the electrochemical growth of ZnO grains has been investigated from a zinc nitrate bath at 70°C on both Ti foil and TiO2 nanotubes. ZnO deposition mechanism has been highlighted through the electrochemical experiments in conjunction with XRD technique and scanning electron microscopy (SEM) examinations. On Ti foils, we show that addition of additives is required to obtain a highly oriented nanostructured ZnO deposit. On TiO2 nanotubes, additives are not necessary to obtain such a deposit: Titania nanotubes can be used to guide the vertical growth of hybrid nanoarchitectured ZnO/TiO2 electrode.

Dry and wet methods of silicon dioxide surface functionalisation with 3-aminopropyl trimethoxysilane: application to fullerene C60 anchoring

A.Grégory Delafosse; Lionel Patrone; Didier Goguenheim — 2012-02-06T23:20:50-05:00

Dry and wet methods of silicon dioxide surface functionalisation with 3-aminopropyl trimethoxysilane: application to fullerene C60 anchoring
A.Grégory Delafosse; Lionel Patrone; Didier Goguenheim
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 312 - 324
In this work, we have studied the formation of self-assembled monolayers (SAM) of 3-aminopropyltrimethoxysilane (APTMS), chemically bound to silicon dioxide surface, prepared using a deposition from both solution and a new solvent-free process, using contact angle measurements, ellipsometry, ATR-FTIR spectroscopy and AFM imaging. In the first part, we have analysed the grafting kinetics of APTMS SAMs to control the formation of a single monolayer. Results show that with the dry deposition method about 4 h are needed to obtain a complete APTMS single monolayer. In parallel, the ordering kinetics of the SAM has been monitored by ATR-FTIR spectroscopy, showing that the monolayer reaches its final order before grafting. The possibility of using the as-obtained APTMS SAMs from wet and dry methods for anchoring functional molecular moieties is then probed with fullerene C60 molecules deposited from a solution. The grafting kinetics of C60 is studied on wetly deposited APTMS, showing a first step at about two monolayers. At last, comparative analysis of C60 grafted on either dryly or wetly deposited APTMS shows that the latter allows obtaining more homogeneous C60 layer. Such results could help in paving the way to the preparation of hybrid C60-based molecular devices on silicon through a bottom-up approach.

Self-organised growth of molecular arrays at surfaces

2012-02-06T23:20:50-05:00

Self-organised growth of molecular arrays at surfaces
L. Porte; M. Abel; P. Amsalem; F. Bocquet; F.C. Bocquet; V. Chevallier; S. Clair; G. Delafosse; S. Desbief; V. Gadenne; L. Giovanelli; M. Koudia; Y. Ksari; C. Loppacher; A. Merlen; L. Nony; O. Ourdjini; L. Patrone; R. Pawlak; J. Romann; J-C. Valmalette; J-M. Themlin
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 325 - 354
The autonomous ordering and assembly of atoms and molecules on atomically well-defined surfaces allow creating a wide range of surface nanostructures, opening an alternative ‘bottom-up’ route to the traditional ‘top-down’ fabrication methods of the microelectronics industry now approaching their fundamental limits. This review summarises some recent efforts of our team to grow molecular arrays on metal, insulating or semiconductor surfaces. In a fundamental approach, two-dimensional surface arrays of nanometre size have been obtained under ultrahigh vacuum by evaporation of molecules, functionalised to favour the intermolecular links rather than molecule&-substrate ones. Intermolecular links such as hydrogen bonds, covalent or coordination bonding were profitably used to create various molecular networks. Alternatively, we also investigated molecular self-assembly from the solution whose architectures are mainly fixed by the molecule-substrate adsorption forces. Molecular assemblies were characterised using Scanning Near-Field Microscopies (Scanning Tunnelling Microscopy, non-contact-Atomic Force Microscopy), whereas electronic and vibrational properties were investigated by surface spectroscopy such as Ultra-Violet and X-ray Photoelectron Spectroscopy, infrared or Surface-Enhanced Raman Spectroscopy.

Thermoelectricity and heat balance in a metal/dot/metal junction

Adeline Crépieux; Fabienne Michelini — 2012-02-06T23:20:50-05:00

Thermoelectricity and heat balance in a metal/dot/metal junction
Adeline Crépieux; Fabienne Michelini
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 355 - 367
In this paper, we report on numerical calculations of stationary thermoelectric responses in a metal/dot/metal junction. We derive the Landauer expressions for both the electric and the heat currents, and first discuss the question of heat balance. Secondly, we calculate the Peltier coefficient in the non-linear response regime, and discuss its relation with the Seebeck coefficient, and finally the figure of merit ZT in the linear response. In all regimes, we show how the applied gate voltage is a key parameter to obtain the maximum thermoelectric efficiency through the nanodevice.

Low-dimensional materials for thermoelectric applications

Pascal Boulet; Marie-Christine Record — 2012-02-06T23:20:50-05:00

Low-dimensional materials for thermoelectric applications
Pascal Boulet; Marie-Christine Record
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 368 - 376
In recent years, increasing awareness and concern for energy resources and the environment have stimulated significant advances in materials and technologies for energy conversion. By using a principle called ‘the Seebeck effect’ thermoelectric modules can convert heat energy to electricity. The efficiency of a thermoelectric material is given by the figure of merit ZT = (S2σ/κ) T, where S is the Seebeck coefficient, T is the temperature, and σ and κ are the electrical and thermal conductivities, respectively. An improvement in ZT can be achieved by increasing S−1>σ or reducing κ. However, in three-dimensional (3D) materials, S, >σ and κ are interrelated. By contrast, when dimensionality of materials is lowered down to the nanometre scale, these parameters can be tuned to some extent independently from one another to some extent. This paper reports on some examples of low-dimensional thermoelectric materials with enhanced properties. Various calculation methods used to predict these properties are also presented, and the added value of the calculations as a complement to experiments in the improvement of thermoelectric materials is particularly stressed.

Iridium (III) complexes as promising emitters for solid-state Light-Emitting Electrochemical Cells (LECs)

Frédéric Dumur; Denis Bertin; Didier Gigmes — 2012-02-06T23:20:50-05:00

Iridium (III) complexes as promising emitters for solid-state Light-Emitting Electrochemical Cells (LECs)
Frédéric Dumur; Denis Bertin; Didier Gigmes
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 377 - 395
Light-emitting Electrochemical Cells (LECs) constitute one of the most recent generations of Organic Light-Emitting Diodes (OLEDs). The main difference between LECs and OLEDs is that LECs include mobile ions in the active layer. Ionic transition-metal complexes and especially ionic iridium (III) complexes have recently attracted widespread attention as potential electroluminescent materials for LECs. Herein, we present an overview of LECs incorporating ionic iridium (III) complexes as phosphorescent emitters. Synthetic strategies developed to introduce iridium (III) complexes in the active layer are also reviewed. Despite the numerous intrinsic drawbacks still remaining, recent advances make iridium-based LECs promising devices for future commercial and scientific applications.

Stress effects on solid-state dewetting of nano-thin films

F. Cheynis; E. Bussmann; F. Leroy; T. Passanante; P. Müller — 2012-02-06T23:20:50-05:00

Stress effects on solid-state dewetting of nano-thin films
F. Cheynis; E. Bussmann; F. Leroy; T. Passanante; P. Müller
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 396 - 411
In this paper, we present a brief survey of stress effects on dewetting. For this purpose, i) we develop a simple thermodynamic model to illustrate stress effects; ii) we study stress effects in strained-Silicon-On-Insulator (s-SOI) thin films by means of Low Energy Electron Microscopy, and Atomic Force Microscopy; iii) we discuss some available data. In particular, we show that while for s-SOI the strain only provides a relatively small contribution to the total driving force for dewetting, in some other cases stress can really dominate the driving force for the dewetting.

Fabrication and growth of GaN-based micro and nanostructures

2012-02-06T23:20:50-05:00

Fabrication and growth of GaN-based micro and nanostructures
Blandine Alloing; Emmanuel Beraudo; Yvon Cordier; Fabrice Semond; Sylvain Sergent; Olivier Tottereau; P. Vennéguès; Stéphane Vézian; Jesús Zúñiga-Pérez
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 412 - 427
GaN is considered as the material of choice for electromechanical, electronic and optoelectronic applications in the visible/UV regions of the electromagnetic spectrum. However, the lack of an adapted substrate results in a very large density of defects, in particular dislocations, stacking faults and cracks. Under these circumstances, the growth of nanostructures appears as an appealing means of circumventing the problem. In this paper, we describe the fabrication and characterisation of GaN-based nanostructures – cantilevers, microdiscs, photonic crystals, micro and nanowires – grown by metallorganic vapour phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) and fabricated either by a bottom-up or a top-down approach. The applications envisaged at CRHEA will be examined.

Boosting the Curie temperature in carbon-doped Mn5Ge3/Ge heterostructures

2012-02-06T23:20:50-05:00

Boosting the Curie temperature in carbon-doped Mn5Ge3/Ge heterostructures
A. Spiesser; M-T. Dau; L.A. Michez; M. Petit; C. Coudreau; A. Glachant; V. Le Thanh
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 428 - 438
We have combined structural and magnetic characterisations to investigate the effect of carbon incorporation in epitaxial Mn5Ge3Cx films grown on Ge(111) by Molecular Beam Epitaxy (MBE). It is shown that up to a carbon content of saturation of ~0.6, most of carbon can be incorporated into the interstitial sites of the Mn5Ge3 lattice. Such a process results in a linear increase in the Curie temperature (TC) of the alloy, which can reach a value as high as ∼430 K. Above this carbon content, TC is found to decrease. Structural characterisations reveal that Mn5Ge3Cx films are in perfect epitaxy when x ∼0.6 whereas cluster formation in the grown layers is detected above that threshold. The clusters can be attributed to manganese carbide (MnC) compounds, which are formed when the carbon content exceeds the saturation value of 0.6 by consuming previously deposited carbon. In addition, we also show that after post-thermal annealing, the carbon-doped Mn5Ge3Cx alloys remain magnetically and structurally stable up to a temperature as high as 1123 K. The obtained results are very promising for integrating Mn5Ge3Cx into ferromagnetic/semiconductor heterostructures, the ultimate goal being the realisation of spintronics devices.

Nanotechnologies dedicated to nucleation control

2012-02-06T23:20:50-05:00

Nanotechnologies dedicated to nucleation control
Nadine Candoni; Zoubida Hammadi; Romain Grossier; Manuel Ildefonso; Eve Revalor; Nathalie Ferté; Tetsuo Okutsu; Roger Morin; Stéphane Veesler
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 439 - 459
This paper highlights the work of our group on the control and the observation of nucleation with techniques using nanotechnologies. This control is performed either by triggering nucleation in time with an external field or by localising it spatially in a microdroplet. Localisation in time using light irradiation induces nucleation by forming radicals; the use of electric field acts locally on the density of the solution. Localisation in space with a microfluidic device produces hundreds of nanovolume crystallisers where concentration and temperature are easily monitored. Thus, accurate statistical studies lead to the nucleation parameters (metastable zone, nucleation rate and polymorphism). Lastly, confinement with a microdroplet generator permits to reach very high supersaturations in fL to pL volumes allowing nucleation of a single crystal per microdroplet. All these methods clearly enhance nucleation in the metastable zone. Finally, they use small quantities of products offering potentialities for the screening of crystallisation conditions and phases (polymorphism).

Feasibility of simultaneous surface topography and XRF mapping using Shear Force Microscopy

2012-02-06T23:20:50-05:00

Feasibility of simultaneous surface topography and XRF mapping using Shear Force Microscopy
M. Dehlinger; C. Dorczynski; C. Fauquet; F. Jandard; D. Tonneau; A. Bjeoumikhov; S. Bjeoumikhova; R. Gubzhokov; A. Erko; I. Zizak; D. Pailharey; S. Ferrero; B. Dahmani
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 460 - 470
Marketed sources equipped with polycapillary optics allow now laboratory X-Ray Fluorescence (XRF) analysis with 5-10 µm lateral resolution. To improve it, we had the idea to use a thin cylindrical X-ray capillary fitted to the XRF detector. The combination with near-field microscopy would then lead to a simultaneous record of both topography and XRF from a sample at µm lateral resolution. For this purpose, we have built a home-made Shear Force Microscope to carry out this experiment in the future.In a first step, we have validated the microscope, operating in SNOM configuration, using test sample consisting in ZnO clusters deposited on a Si3N4 grating. Second, the feasibility of XRF collection through a thin X-ray cylindrical capillary on Co/Ti sample is shown in this work. The results suggest that sub-1 µm in-lab XRF analysis is possible, replacing the optical fibre of our SNOM apparatus by an X-ray capillary. On the basis of modelling our results, we then further discuss the possibility to reach 100 nm XRF resolution, combined to surface topography, working in synchrotron environment.

Role of the active layer thickness on the sensitivity of WO3 gas sensors

K. Aguir; J. Guérin; N. Mliki; M. Bendahan — 2012-02-06T23:20:50-05:00

Role of the active layer thickness on the sensitivity of WO3 gas sensors
K. Aguir; J. Guérin; N. Mliki; M. Bendahan
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 471 - 479
Sensitive materials in gas sensors are often polycrystalline semiconducting oxides such as WO3, SnO2, CuO or ZnO. They are most often composed of nanometric grains. They can be deposited either as thin or thick films. The film thickness plays an important role in the response stability and sensitivity of sensors. It is now well accepted that the relationship between the surface and volume of the sensitive layer plays a major role in the efficiency of detection. Many experimental and theoretical works were reported in explaining the experimental sensitivity vs. thickness relationships reported for the gas sensors prepared by different fabrication techniques. In addition, significant changes can be expected by adding catalytic nanograins in small quantities on the surface of the sensitive layers. For example, cobalt nanograins deposited on the surface of WO3 sensors produce an important change in the WO3 conductance. Indeed, cobalt changes the conduction type of the sensors from n- to p-type. This paper describes the effect of reducing the size of the sensors and nanostructured sensitive materials on the sensor response.

Erbium-doped nanoparticles in silica-based optical fibres

Wilfried Blanc; Valérie Mauroy; Bernard Dussardier — 2012-02-06T23:20:50-05:00

Erbium-doped nanoparticles in silica-based optical fibres
Wilfried Blanc; Valérie Mauroy; Bernard Dussardier
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 480 - 487
Developing of new rare-earth (RE)-doped optical fibres for power amplifiers and lasers requires continuous improvements in the fibre spectroscopic properties (like shape and width of the gain curve, optical quantum efficiency, resistance to spectral hole burning and photodarkening...). Silica glass as a host material for fibres has proved to be very attractive. However, some potential applications of RE-doped fibres suffer from limitations in terms of spectroscopic properties resulting from clustering or inappropriate local environment when doped into silica. To this aim, we present a new route to modify some spectroscopic properties of RE ions in silica-based fibres based on the incorporation of erbium ions in amorphous dielectric nanoparticles, grown in-situ in fibre preforms. By adding alkaline earth elements, in low concentration into silica, one can obtain a glass with an immiscibility gap. Then, phase separation occurs under an appropriate heat treatment. We investigated the role of three alkaline-earth elements: magnesium, calcium and strontium. We present the achieved stabilisation of nanometric erbium-doped dielectric nanoparticles within the core of silica fibres. We present the nanoparticle dimensional characterisation in fibre samples. We also show the spectroscopic characterisation of erbium in preform and fibre samples with different compositions. This new route could have important potentials in improving RE-doped fibre amplifiers and laser sources.

Near field optical microscopy: a brief review

A.L. Lereu; A. Passian; Ph. Dumas — 2012-02-06T23:20:50-05:00

Near field optical microscopy: a brief review
A.L. Lereu; A. Passian; Ph. Dumas
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 488 - 501
Near Field Optical Microscopy (NSOM) has evolved into a mature member of the family of scanning probe microscopy. In this article, we briefly go over the principle of NSOM, its breakthroughs and setbacks. We will describe some of the most commonly used NSOM modalities and conclude with the recent advances based on optical nanoantennas. We will then highlight the potential of this high-resolution optical microscopy for chemical and biological applications as well as for materials sciences.

Nanodrug potential in cancer therapy: efficacy/toxicity studies in cancer cells

2012-02-06T23:20:50-05:00

Nanodrug potential in cancer therapy: efficacy/toxicity studies in cancer cells
Alessandra Pagano; Stéphane Honoré; Marie-Anne Estève; Diane Braguer
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 502 - 516
The interest of nanotechnology to find a more effective approach for drug delivery is growing fast. Nanoparticles as drug vehicles potentially improve the pharmacokinetic and pharmacodynamic properties of various types of drugs, and provide a tool to visualise molecules and tumour target cells that otherwise cannot be detected through conventional imaging. However, there are many aspects of nanoparticle formulation, characterisation and their effect on delivery of drugs and therapeutics that remain to be explored. This review summarises the main characteristics of nanoparticles for drug delivery in cancer treatment, and describes an experimental approach for evaluating efficacy and toxicity of nanocarriers in cancer cells.

Plastic neuronal probes for implantation in cortical and subcortical areas of the rat brain

2012-02-06T23:20:50-05:00

Plastic neuronal probes for implantation in cortical and subcortical areas of the rat brain
Esma Ismailova; Thomas Doublet; Dion Khodagholy; Pascale Quilichini; Antoine Ghestem; Sang Yoon Yang; Christophe Bernard; George G. Malliaras
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 517 - 528
We discuss the fabrication of flexible implantable probes for recording neuronal activity in the rat brain. We fabricated such probes bearing 12 platinum electrodes, using polyimide as a substrate and SU-8 as an insulation layer. The fabrication process was simplified through the use of laser ablation to define the probe outline. The probes showed not only good mechanical flexibility but also the required stiffness for implantation. Histology results and electrical recordings of neuronal activity lend support to the idea that the combination of polyimide and SU-8 represents a good choice of materials for the fabrication of implantable neuronal probes.

Microfluidic tools to investigate pathologies in the blood microcirculation

2012-02-06T23:20:50-05:00

Microfluidic tools to investigate pathologies in the blood microcirculation
Pascal Preira; Thomas Leoni; Marie-Pierre Valignat; Annemarie Lellouch; Philippe Robert; Jean-Marie Forel; Laurent Papazian; Guillaume Dumenil; Pierre Bongrand; Olivier Théodoly
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 529 - 547
We show how microfluidics technology can be used to fabricate simple and innovative biomimetic tools to shed new light on physiopathological events occurring in the blood microcirculation. Examples of applications are given in the context of the acute respiratory distress syndrome (ARDS), an inflammatory disease of the lung triggered by a massive arrest of white blood cells in the lung microvasculature. The main challenge consists in building relevant micro-devices to reproduce key biological characteristics of blood capillaries. We present a series of tools that permit us to decouple the role of the multiple parameters involved in complex biological events. Straight narrow channels with non-adherent walls are used to characterise the passage of a cell in 4 m wide constrictions in the absence of adhesion, whereas channels covered by endothelial cells allow a quantitative measurement of cell adhesion in the absence of mechanical constraints. We show that incubation of white blood cells in sera of ARDS patients increases their stiffness, confirming the role of stiffness on the abnormal sequestration of white blood cells, whereas we could not bring to light a significant adhesion increase. The multiple branches and constrictions of the blood microvasculature network are mimicked here by series of interconnected crenelled constrictions with different symmetries. In symmetric crenels, cells adopt a stable deformed shape after a few constrictions and travel fast through successive constrictions with a constant orientation. In asymmetric channels, cell orientation and trajectory are perturbed between two constrictions. Unfavourable orientations upon entry can yield temporary or even definitive arrests with the stiffest cells. Finally, we present a new artificial micro-vessel with porous walls to mimic the porosity of real blood vessels. This new tool is useful to observe directly under a microscope the late stages of inflammation in the microvasculature such as immune cells transmigration, or the infection of a micro-vessel by pathogenic bacteria.

Advanced microscopy techniques for biological imaging

Serge Monneret; Sophie Brasselet — 2012-02-06T23:20:50-05:00

Advanced microscopy techniques for biological imaging
Serge Monneret; Sophie Brasselet
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 548 - 566
We show that using phase and polarisation information in optical microscopy can provide new insights into biomolecular processes for biological functional imaging. Quantitative phase imaging is demonstrated in living cells with promising capabilities in terms of cells composition and morphology studies. Polarisation-resolved non-linear optical microscopy is described in tissues and lipid membranes with emphasis on the specific properties of two-photon excited fluorescence, Second Harmonic Generation and Coherent Anti-Stokes Raman Imaging. These techniques, based on far field microscopy, provide new information at the molecular scale, complementary to more traditional fluorescence microscopy techniques.

Regular arrays of palladium and palladium-gold clusters supported on ultrathin alumina films: stability under oxygen

2012-02-06T23:20:50-05:00

Regular arrays of palladium and palladium-gold clusters supported on ultrathin alumina films: stability under oxygen
Georges Sitja; Maxence Marsault; Frédéric Leroy; Séverine Le Moal; Claude R. Henry
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 567 - 575
Grazing Incidence Small Angle X-ray Scattering (GISAXS) studies were conducted to determine the effect of oxygen on regular arrays of mono (Pd)- and bimetallic (Pd-Au) clusters. Unlike bimetallic Pd-Au particles, pure palladium clusters are not stable at a partial oxygen pressure of 10−6 mbar. A comparison of the experimental data with Fourier transforms of known distributions reveals that Pd clusters move and that their aspect ratio increases. These results are explained by the adsorption of oxygen that changes the equilibrium shape of the Pd particles and reduces the adhesion energy. In the case of bimetallic Pd-Au clusters, the presence of Au on the surface of the particle prevents adsorption of oxygen.

Structure and properties of nanoscale materials: theory and atomistic computer simulation

2012-02-06T23:20:50-05:00

Structure and properties of nanoscale materials: theory and atomistic computer simulation
C. Bichara; P. Marsal; C. Mottet; R. Pellenq; F. Ribeiro; A. Saúl; G. Tréglia; H.-Ch. Weissker
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 576 - 604
We present a review of a few research topics developed within the "Theory and Atomistic Computer Simulation" Department at CINaM. The bottom line of the scientific activity is to use up-to-date theoretical and computer simulation techniques to address physics and materials science problems, often at the nanometric scale, in close contact with experimental groups. It ranges from the study of the structure and properties of molecular systems for organic electronics to metallic clusters and alloys, magnetic oxides, nuclear fuels and carbon-based nanostructures. These studies are motivated by fundamental research questions as well as more applied goals including environmental and energy issues, or information technologies. This broad spectrum of activities requires a large range of techniques, from theory and ab initio calculations to semi-empirical models incorporated in Monte Carlo or molecular dynamics simulations.

Indigo/sepiolite nanohybrids: stability of natural pigments inspired by Maya blue

Françoise Giulieri; Sonia Ovarlez; Anne-Marie Chaze — 2012-02-06T23:20:50-05:00

Indigo/sepiolite nanohybrids: stability of natural pigments inspired by Maya blue
Françoise Giulieri; Sonia Ovarlez; Anne-Marie Chaze
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 605 - 617
Maya blue is formed from insertion of indigo into palygorskite and sepiolite. Sepiolite and palygorskite are porous fibrous clays. Controlling the insertion, location and organisation of organic molecules in the cavities of nanotubes associated with the release or stability of these molecules is a crucial challenge in the evolution towards unusual properties in nanotechnologies. We validate simple FTIR analyses able to determine the location of indigo in or outside the pores of the fibres. Then, we compare the stability of indigo/palygorskite and indigo/sepiolite systems obtained from similar formulations. The heating treatment is stopped when all indigo is complexed with the clay. We show that in these conditions indigo/palygorskite is more stable than indigo/sepiolite. The formation of stable pigment is more complicated for indigo-sepiolite than for indigo-palygorskite.

Morphology and reactivity of aluminium nanocrystalline powders

2012-02-06T23:20:50-05:00

Morphology and reactivity of aluminium nanocrystalline powders
Bérangère André; Marie-Vanessa Coulet; Myriam Dumont; Jacques Rogez; Vasile Heresanu; Benoit Rufino; Renaud Bouchet; Renaud Denoyel
International Journal of Nanotechnology, Vol. 9, No. 3/4/5/6/7 (2012) pp. 618 - 629
Aluminium powders obtained by mechanical milling are characterised in terms of morphology, nanostructure and thermal properties. Platelets like particles with a thickness in the micrometre range are obtained. It is shown that these platelets are constituted of many nanocrystallites whose size governs the melting behaviour of the powders. Their reactivity towards oxygen is compared with that of spherical particles. Samples obtained by mechanical milling start to be oxidised at a higher temperature the amount of oxidised material is higher than that in the case of spherical particles having the same surface area. Both the thermal behaviour and the reactivity could be explained by the presence of alumina at the grain boundaries. This work shows that the milling process appears as a good alternative to gas condensation methods or wire electro-explosion processes to prepare highly reactive particles.