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Amato M.,CNRS Fundamental Electronics Institute | Palummo M.,European Theoretical Spectroscopy Facility | Rurali R.,CSIC - Institute of Materials Science | Ossicini S.,CNR Institute of Neuroscience | Ossicini S.,University of Modena and Reggio Emilia
Chemical Reviews | Year: 2014

The different employed growth techniques for silicon-germanium (SiGe) nanowires, their morphology and structural properties were discussed. Significant progresses toward a precise control of the NWs composition were subsequently made in chemical vapor deposition using an appropriate gas inlet ratio in an optimum temperature range or tuning the total growth pressure. Long and straight, without significant tapering, SiGe NWs were obtained through the use of additional gases, other than the usual precursor. Regarding the morphology both axial and radial heterostructures have been reported so far. When laser ablation and CVD techniques were combined, axially modulated SiGe NWs of different diameters were produced. A better control of the interface sharpness, of the order of 1nm, has been then reached combining vapor-liquid-solid (VLS) and vapor-solid-solid (VSS) growth. It is clear that SiGe nanowires will play an important role in the next generation of advanced miniaturized devices.

Hotzer B.,CNRS Fundamental Electronics Institute | Medintz I.L.,Center for Bio Molecular Science and Engineering | Hildebrandt N.,CNRS Fundamental Electronics Institute
Small | Year: 2012

Nanobiotechnology is one of the fastest growing and broadest-ranged interdisciplinary subfields of the nanosciences. Countless hybrid bio-inorganic composites are currently being pursued for various uses, including sensors for medical and diagnostic applications, light- and energy-harvesting devices, along with multifunctional architectures for electronics and advanced drug-delivery. Although many disparate biological and nanoscale materials will ultimately be utilized as the functional building blocks to create these devices, a common element found among a large proportion is that they exert or interact with light. Clearly continuing development will rely heavily on incorporating many different types of fluorophores into these composite materials. This review covers the growing utility of different classes of fluorophores in nanobiotechnology, from both a photophysical and a chemical perspective. For each major structural or functional class of fluorescent probe, several representative applications are provided, and the necessary technological background for acquiring the desired nano-bioanalytical information are presented. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Algar W.R.,University of British Columbia | Kim H.,University of British Columbia | Medintz I.L.,Center for Bio Molecular Science and Engineering | Hildebrandt N.,CNRS Fundamental Electronics Institute
Coordination Chemistry Reviews | Year: 2014

Förster resonance energy transfer (FRET) configurations incorporating colloidal semiconductor quantum dots (QDs) have proven to be a valuable tool for bioanalysis and bioimaging. Mirroring well established techniques with only fluorescent dyes, "traditional" FRET configurations with QDs have involved single-step energy transfer to organic dye acceptors mediated by biomolecular interactions. Here, we review recent progress in characterizing non-traditional FRET configurations incorporating QDs and their application to challenges in biosensing, energy conversion, and fabrication of optoelectronic devices. Such non-traditional FRET configurations with QDs include substitution of organic dyes with lanthanide complexes, polypyridyl transition metal complexes, azamacrocyclic metal complexes, graphene (oxide), carbon nanotubes, gold nanoparticles, and dyes exhibiting photochromism. Other non-traditional configurations of interest include FRET relays (with or without organic dyes) that feature multiple sequential energy transfer steps, and thin films of QDs where discrete FRET pairs cannot be defined, including those where QDs are layered in a size-sequential or "rainbow" structure. The calculation of FRET efficiencies and donor-acceptor distances in the above configurations are reviewed, as are distance scaling relationships for non-zero dimensional acceptors, and the related dipolar energy transfer mechanism, nanosurface energy transfer (NSET). To illustrate the utility of non-traditional QD-FRET configurations, we highlight examples of optically switchable probes, photonic wires, time-gated and multiplexed probes for biosensing, enhanced light harvesting in QD and dye sensitized solar cells (DSSC), and colour conversion in light emitting diodes (LEDs). We close by providing a perspective on how the combined utility of these non-traditional QD-FRET configurations may be useful for engineering complex nanoscale devices in the future. © 2013 Elsevier B.V.

Wegner K.D.,CNRS Fundamental Electronics Institute | Hildebrandt N.,CNRS Fundamental Electronics Institute
Chemical Society Reviews | Year: 2015

Semiconductor quantum dots (QDs) have become important fluorescent probes for in vitro and in vivo bioimaging research. Their nanoparticle surfaces for versatile bioconjugation, their adaptable photophysical properties for multiplexed detection, and their superior stability for longer investigation times are the main advantages of QDs compared to other fluorescence imaging agents. Here, we review the recent literature dealing with the design and application of QD-bioconjugates for advanced in vitro and in vivo imaging. After a short summary of QD preparation and their most important properties, different QD-based imaging applications will be discussed from the technological and the biological point of view, ranging from super-resolution microscopy and single-particle tracking over in vitro cell and tissue imaging to in vivo investigations. A substantial part of the review will focus on multifunctional applications, in which the QD fluorescence is combined with drug or gene delivery towards theranostic approaches or with complementary technologies for multimodal imaging. We also briefly discuss QD toxicity issues and give a short outlook on future directions of QD-based bioimaging. This journal is © The Royal Society of Chemistry 2015.

Kim J.-V.,CNRS Fundamental Electronics Institute
Solid State Physics - Advances in Research and Applications | Year: 2012

Spin-transfer torques in magnetic heterostructures give rise to a number of dynamical processes that are not accessible with magnetic fields alone. A prominent example involves self-sustained magnetization oscillations, which are made possible through the compensation of magnetic damping by the transfer of spin angular momentum from a spin-polarized current. In this contribution, the theoretical aspects of magnetization oscillations driven by spin torques, such as spin waves and vortex gyration, are presented in detail and key experimental results are highlighted. It is shown how simple but useful models can be derived from fundamental theories of magnetization dynamics and used to describe a variety of stochastic and nonlinear phenomena. © 2012 Elsevier Inc.

Hildebrandt N.,CNRS Fundamental Electronics Institute | Wegner K.D.,CNRS Fundamental Electronics Institute | Algar W.R.,University of British Columbia
Coordination Chemistry Reviews | Year: 2014

Optical quantification of several biomarkers at very low concentrations and nanometric distances has become an important requirement for many biosensing applications. Förster resonance energy transfer (FRET) and, in particular, luminescent terbium complex (LTC)-based FRET, is a valuable tool for sensitive and versatile multiplexed FRET. Here, we review recent progress in the development of novel LTC-FRET photonic sensors for ultra-sensitive and multiplexed diagnostics of various biomarkers and distances (molecular ruler) in different biological systems. The basic concept of FRET, the exceptional photophysical properties of LTCs, and possibilities and opportunities for multiplexed optical sensing are outlined. Sophisticated FRET systems such as multiplexed LTC-to-dye FRET, LTC-to-quantum dot (QD) FRET, and LTC-to-QD-to-dye FRET relays have been assembled with biological recognition molecules such as antibodies, peptides, and oligonucleotides to permit biosensing applications in the form of homogeneous immunoassays, DNA hybridization and enzyme assays, and molecular logic devices. A perspective on the emerging field of multiplexed LTC-based FRET biosensing is given at the end of this review to highlight the promising future of these nanometric biosensors. © 2014 Elsevier B.V.

Jin Z.,CNRS Fundamental Electronics Institute | Hildebrandt N.,CNRS Fundamental Electronics Institute
Trends in Biotechnology | Year: 2012

The need for companion diagnostics, point-of-care testing (POCT) and high-throughput screening in clinical diagnostics and personalized medicine has pushed the need for more biological information from a single sample at extremely low concentrations and volumes. Optical biosensors based on semiconductor quantum dots (QDs) can answer these requirements because their unique photophysical properties are ideally suited for highly sensitive multiplexed detection. Many different biological systems have been successfully scrutinized with a large variety of QDs over the past decade but their future as widely applied commercial biosensors is still open. In this review, we highlight recent in vitro diagnostic and cellular imaging applications of QDs and discuss milestones and obstacles on their way toward integration into real-life diagnostic and medical applications. © 2012 Elsevier Ltd.

Colombelli R.,CNRS Fundamental Electronics Institute | Manceau J.-M.,CNRS Fundamental Electronics Institute
Physical Review X | Year: 2015

Cavity polaritons are mixed states, partially microcavity photon and partially material excitation, which behave as bosons up to a critical density. In the case of excitonic polaritons, the critical parameter is the Mott density, which cannot be tailored, in a given material system. Interestingly, in the case of intersubband polaritons, such critical density can be engineered to a large extent via the doping. We show that this observation has crucial implications for intersubband polariton lasers, and we make a strong case in favor of their development.

Hildebrandt N.,CNRS Fundamental Electronics Institute
ACS Nano | Year: 2011

Semiconductor quantum dots possess unique photophysical properties such as bright emission with narrow wavelength bandwidth and extremely broad and strong absorption. In combination with their size-dependent color tunability, quantum dots have been proposed as ideal candidates for multiplexed optical bioanalysis for more than a decade. However, the unavailability of stable, reproducible, biocompatible quantum dots with controlled and functional multiple biolabeling has restricted these nanocrystals to research applications. In this issue of ACS Nano, Jennings et al. demonstrate the versatile use of quantum dot antibody conjugates produced by commercially available kits that allow an easy and fast labeling. This Perspective highlights the potential of novel quantum dot bioconjugation approaches in combination with state-of-the-art detection methods and technologies for successful and widely applicable multiplexed biosensing. © 2011 American Chemical Society.

Sirtori C.,University Paris Diderot | Barbieri S.,University Paris Diderot | Colombelli R.,CNRS Fundamental Electronics Institute
Nature Photonics | Year: 2013

Quantum cascade lasers are compact devices based on mature compound semiconductors such as GaAs that take advantage of highly developed optoelectronic fabrication techniques to integrate linear and nonlinear functions. This Review discusses terahertz-wave engineering using quantum cascade lasers with a particular focus on techniques that have been implemented to control their spectral and output beam properties. After briefly introducing the types of active regions and surveying present maximum operating temperatures, we review several photonic structures used for frequency and beam engineering, ranging from distributed feedback lasers to photonic crystals. We then describe techniques that allow the upconversion of terahertz quantum cascade laser radiation in the near-infrared region using nonlinear intracavity mixing. Finally, we review frequency stabilization of terahertz quantum cascade lasers with a special emphasis on phase locking to near-infrared frequency combs. © 2013 Macmillan Publishers Limited. All rights reserved.

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