Les auteurs tiennent à remercier le soutien financier par le Labex-Imust.

1. Préparation de l&#39;échantillon biologique Toutes les expériences décrites dans cette étude ont été approuvés par le Comité de protection et d&#39;utilisation des animaux de la CECCAPP (Lyon, France) (autorisation # LYONSUD_2012_004), et les expériences ont été réalisées sous la supervision de personnes autorisées (L. Sancey, DDPP autorisation # 38 05 32). <ol><li> Ajouter 1 ml de H 2 O à 100 pmol de nanoparticules à base de gadolinium-(Gd), attendre 15 minutes, et ajouter 20 ul de HEPES 50 mM, NaCl 1,325 M, CaCl2 20 mM à 100 pi de H 2 O et 80 pi de la solution primaire de nanoparticules à base de Gd pour obtenir une solution de 200 pi à 40 mM prêts à injecter (Ville: Villeurbanne, au laboratoire). </li><li> Injecter la solution de nanoparticules à base de Gd-200 de pi par voie intraveineuse à des rongeurs porteurs de tumeurs anesthésiés (Ville: Lyon Sud (Oullins), à 15 km de laboratoire). </li><li> 1-24 heures après l&#39;injection, les souris sacrifier uned placer les échantillons biologiques dans l&#39;isopentane refroidi par de l&#39;azote liquide. Conserver les échantillons à - 80 ° C (Ville: Lyon Sud (Oullins), à 15 km du laboratoire). </li><li> Couper l&#39;échantillon (Ville: généralement Grenoble, 100 km de laboratoire, je vais essayer d&#39;avoir un accès à Lyon Sud) en 100 diapositives um d&#39;épaisseur et de mettre les diapositives biologiques sur des plats en plastique spécifiques (boîte de Pétri). Conserver à -80 ° C. Remarque: plats en plastique sont essentiellement un échantillon de polymère très pur. Ils sont utilisés pour éviter les interférences avec les éléments contenus dans le tissu. </li></ol> 2. Préparation de l&#39;échantillon pour l&#39;étalonnage <ol><li> Préparer les flacons avec des doses croissantes de nanoparticules à base de Gd dans de l&#39;eau (0 nM, 100 nM, 500 nM, 1 uM, 5 uM, 10 uM, 50 uM, 100 uM, 500 uM, 1 mM et 5 mM). </li><li> Mettez un ul-goutte de chaque solution régulièrement espacées de 3 mm sur la boîte de Pétri 5. </li><li> À sec à la température ambiante pendant 20 min. </li></ol>3. LIBS Expérience <ol><li> Initialisation de la configuration du LIBS <ol><li> Paramètres laser. Après la mise sur les instruments, attendre 10-20 min pour l&#39;impulsion laser stabilisation de l&#39;énergie et de refroidissement de la caméra ICCD à -20 ° C. Régler l&#39;énergie d&#39;impulsion avec l&#39;atténuateur. Remarque: Les paramètres du laser optimales pour les tissus de cartographie sont 5 ns durée d&#39;impulsion, 1064 nm longueur d&#39;onde, et l&#39;énergie d&#39;impulsion d&#39;environ 4 mJ. Le laser utilise un laser Nd est typique: YAG laser nanoseconde. </li><li> LIBS Paramètres. Régler la position de focalisation du laser (par rapport à la surface de l&#39;échantillon) pour obtenir le diamètre du cratère plus petit (environ 50 pm ou moins). Remarque: Ce qui correspond à une focalisation d&#39;impulsions laser de 100 um en dessous de la surface de l&#39;échantillon. </li><li> Paramètres du spectromètre. Utilisez le spectromètre Czerny-Turner combiné avec un 1200 traits / mm et une résolution de la caméra ICCD temporelle. Contrôler tous ces dispositifs par ordinateur. Réglez la valeur de la fente d&#39;entrée à 40 um. Définissez la plage spectrale rements concernant l&#39;élément à analyser. Utilisez la gamme spectrale couvrant 325 à 355 nm pour détecter Dieu avec une grande sensibilité, ainsi que Na, Cu et Ca. Définissez les paramètres de l&#39;ICCD avec un retard de 300 ns, une porte de 2 ps, et un gain de 200. </li></ol></li><li> Cartographie mesure <ol><li> Placer l&#39;échantillon biologique sur le support d&#39;échantillon motorisé LIBS. </li><li> Ajuster la hauteur de l&#39;échantillon en fonction de la position de focalisation du laser. </li><li> Prenez une photo à haute résolution de la tranche d&#39;échantillon. </li><li> Réglez le module de cartographie du logiciel d&#39;acquisition LIBS pour effectuer une carte avec typiquement 100 x 100 points de mesure espacés par une résolution d&#39;environ 100 um. </li><li> Lancement de l&#39;acquisition. De ce point tout automatiser; le déplacement séquence ainsi que l&#39;enregistrement du spectre et l&#39;épargne. 40 min sont nécessaires pour une mise en correspondance des points de 10 000 (équivalent à 1 cm 2 à une résolution de 100 um). Regrouper tous les spectres enregistrés dans un même fichier. </li><li> Lorsque finished, prendre une deuxième photo de la tranche d&#39;échantillon </li></ol></li><li> Calibration Mesure </li></ol> Avec les mêmes paramètres expérimentaux, mesurer les échantillons d&#39;étalonnage (pour plus de détails de préparation, voir rubrique 2). Effectuer une carte ou un disque 25 spectres (obtenus à partir de sites de mesure dans la partie centrale de la goutte) dans chacune des gouttes d&#39;étalonnage. 4 LIBS analyse de spectre. Construire des images chimiques <ol><li> Record de tous les spectres LIBS de la cartographie du tissu et de les charger dans le logiciel d&#39;analyse LIBS. Soustraire la ligne de base pour chaque spectre et construire les images chimiques avec échelle d&#39;intensité relative en utilisant une fausse couleur. Remarque: Un algorithme récupère les intensités des raies spécifiques, tels que D.ieu, Cu, Na, Ca ou. </li><li> Effectuez la même opération sur les spectres mesurés à partir de l&#39;échantillon calibré pour permettre le calcul des courbes d&#39;étalonnage (relation entre l&#39;intensité et la concentration) et de construire aqcarte uantitative ou l&#39;image pour D.ieu (ou autre élément d&#39;intérêt). </li><li> Appliquer les traitements adéquats pour les images chimiques, tels que l&#39;interpolation ou de lissage. Sauvez les cartes d&#39;intensité ou de concentration dans le format d&#39;image (bitmap). </li></ol>

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Les auteurs n&#39;ont rien à révéler.

Appliqué à l&#39;échantillon biologique, cette technique permet l&#39;imagerie chimique, à savoir la cartographie et la quantification, de D.ieu et Si à partir de nanoparticules à base de Gd injectés dans différents organes. Des principaux paramètres critiques, le contrôle des propriétés laser (de longueur d&#39;onde, l&#39;énergie d&#39;impulsion, de focalisation, et de stabilité) est essentiel pour une ablation de tissus fins et précis (c.-à-résolution de la cartographie) ainsi que p...

Le large développement de nanoparticules pour des applications biologiques exhorté l&#39;amélioration parallèle de techniques analytiques pour leur quantification et de l&#39;imagerie dans des échantillons biologiques. Habituellement, la détection et la cartographie des nanoparticules dans les organes sont fabriqués par fluorescence ou microscopie confocale. Malheureusement, ces méthodes nécessitent l&#39;étiquetage des nanoparticules par un colorant infrarouge proche qui peut modifier la biodistribution des nanoparticules, en particulier pour de très petites nanoparticules en raison de ses propriétés hydrophobes. La détection des nanoparticules marquées, et en particulier les très petites nanoparticules (taille &lt;10 nm), pourrait donc interférer avec leur biodistribution à toute l&#39;échelle du corps, mais aussi au niveau de tissus et cellules. Le développement de nouveaux dispositifs capables de détecter des nanoparticules sans étiquetage offre de nouvelles possibilités pour l&#39;étude de leur comportement et de la cinétique. En outre, le rôle des oligo-éléments tels que le fer et le cuivre dans un cerveau maladiesd maladies neurodégénératives telles que la maladie d&#39;Alzheimer 1, Menkes 2,3, ou 4 Wilson suggèrent l&#39;intérêt d&#39;étudier et de localiser ces éléments dans les tissus. Diverses techniques ont été utilisées pour fournir la cartographie élémentaire ou microanalyse des matériaux différents. Dans leur article de synthèse publié en 2006, R. Lobinski et al. Donne un aperçu des techniques standard disponibles pour la microanalyse élémentaire en milieu biologique, l&#39;un des environnements les plus difficiles pour les sciences analytiques 5. La microsonde électronique, qui se compose de dispersion d&#39;énergie micro-analyse aux rayons X dans un microscope électronique à transmission, peut être appliquée à de nombreuses études, si la concentration de l&#39;élément est suffisante (&gt; 100-1000 pg / g). Pour atteindre des seuils de détection inférieurs, les techniques suivantes ont été utilisées: <ul><li> microsonde faisceau d&#39;ions en utilisant des particules induit par émission de rayons X μ-PIXE (1-10 ug / g) 6 </li><li> synchrotron microanalyse de rayonnement μ-SXRF (0,1-1 mg / g) 7 </li><li> secondaire spectrométrie de masse d&#39;ions SIMS (0,1 pg / g) 8 </li><li> ablation laser couplé par induction spectrométrie de masse LA-ICP-MS (à partir de 0,01 pg / g) 9,10 </li></ul> Les techniques mentionnées ci-dessus fournissent une résolution micrométrique comme indiqué dans le tableau 1 extraite de Lobinski et al. Reconstruction 3D des enquêtes 2D série pourrait également être proposé pour la reconstruction des tissus plus profonds 11. Cependant, tous les appareils et systèmes exigent des professionnels qualifiés, modérés à l&#39;équipement très coûteux et des expériences durables (généralement plus de 4 h pour un 100 um x 100 um pour μ-SXRF et 10 mm x 10 mm pour LA-ICP-MS ) 12. Au total, ces exigences font microanalyse élémentaire très contraignant et incompatible avec les systèmes d&#39;imagerie optique classiques,la microscopie à fluorescence ou microscopie non linéaire. Un autre point que nous ne pouvons mentionner ici est que la capacité de mesure quantitative est encore assez limitée et dépend de la disponibilité des normes de laboratoire adaptation matricielle. La poursuite de la généralisation de l&#39;utilisation de la microanalyse élémentaire dans les processus de l&#39;industrie, de la géologie, de la biologie et autres domaines d&#39;applications va générer des percées conceptuelles et technologiques importants. Le but de la présente manuscrit est de proposer des solutions pour la cartographie élémentaire quantitative (ou microanalyse élémentaire) dans les tissus biologiques avec une instrumentation de table entièrement compatible avec la microscopie optique classique. Notre approche est basée sur la spectroscopie par claquage laser (technologie LIBS). Dans LIBS, une impulsion de laser est focalisé sur l&#39;échantillon d&#39;intérêt pour créer la ventilation et l&#39;étincelle de la matière. Le rayonnement émis atomique dans le plasma est ensuite analysé par un spectromètre et l&#39;élémentaireconcentrations mentales peuvent être récupérées avec des mesures d&#39;étalonnage effectuées au préalable 13,14. Les avantages de la LIBS comprennent sensibilité (pg / g pour presque tous les éléments), la compacité, la préparation des échantillons très basique, l&#39;absence de contact avec l&#39;échantillon, une réponse instantanée et précisément localisée (micro) analyse de surface. Toutefois, l&#39;application de l&#39;imagerie chimique des tissus reste difficile car l&#39;ablation laser de tissu doit être finement contrôlée pour effectuer des cartes à haute résolution spatiale avec sensibilité dans la gamme pg / g 15,16. Avec une telle solution, l&#39;adjonction de traceurs ou d&#39;agents d&#39;étiquetage n&#39;est pas nécessaire, ce qui permet de détecter des éléments inorganiques directement dans leur environnement naturel dans les tissus biologiques. L&#39;instrument LIBS développée dans notre laboratoire offre une résolution de courant inférieure à 100 um avec une sensibilité estimée pour Gd-dessous de 35 pg / g, ce qui équivaut à 0,1 mM 16, qui permetla cartographie des grands échantillons (&gt; 1 cm 2) dans les 30 min. En outre, le logiciel maison facilite l&#39;acquisition et l&#39;exploitation des données. Cet instrument est utilisé pour détecter, carte, et de quantifier la distribution tissulaire de gadolinium nanoparticules à base de (Gd) de 17 à 18 dans les reins et les échantillons de tumeur de petits animaux, de 1 à 24 h après l&#39;injection intraveineuse de particules (taille &lt;5 nm) . Les éléments inorganiques, qui sont incorporées à un tissu biologique, tels que Fe, Ca, Na et P, ont également été détectées et imagée.

<table border="0" cellpadding="0" cellspacing="0" width="747">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laser nanosecond Nd:YAG</td>
			<td style="width:129px;">Quantel</td>
			<td style="width:119px;">Brillant</td>
			<td style="width:283px;">5ns pulse witdh, wavelength 1064 nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Spectrometer</td>
			<td>Andor Technology</td>
			<td>Shamrock 303</td>
			<td>with 1200 l/mm blazed at 300 nm grating</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Detector ICCD</td>
			<td>Andor Technology</td>
			<td style="width:119px;">Istar</td>
			<td>2 ns temporal resolution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">LIBS Unit</td>
			<td style="width:129px;">ILM</td>
			<td style="width:119px;"></td>
			<td>Homemade Instrumentation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:129px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gd-based nanoparticles</td>
			<td style="width:129px;">Nano-H</td>
			<td style="width:119px;"></td>
			<td>particles</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HEPES</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">H4034</td>
			<td>for particle&#39;s dilution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CaCl2</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">21108</td>
			<td>for particle&#39;s dilution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaCl</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">S5886</td>
			<td>for particle&#39;s dilution</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">mice</td>
			<td style="width:129px;">Charles River</td>
			<td style="width:119px;">depending of animal breeding</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">isoflurane</td>
			<td style="width:129px;">Coveto / Virbac</td>
			<td style="width:119px;"></td>
			<td>for anaesthesia - Isofluranum</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">isopentane</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">59060</td>
			<td>to froze the sample&#160; slowly</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">liquide nitrogen</td>
			<td style="width:129px;">Air Liquide</td>
			<td style="width:119px;"></td>
			<td>to cool down the isopentane</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">cryostat</td>
			<td style="width:129px;">Leica</td>
			<td style="width:119px;">CM-3050S</td>
			<td>to slide the samples</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">petri dishes</td>
			<td style="width:129px;">Dutscher</td>
			<td style="width:119px;">353004</td>
			<td>to stick the sample</td>
		</tr>
	</tbody>
</table>

laser-induced breakdown spectroscopy: a new approach for nanoparticle's mapping and quantification in organ tissue

spectroscopie d&#39;émission de plasma induit par laser a été appliqué à l&#39;analyse élémentaire d&#39;échantillons biologiques. Spectroscopie de rupture induite au laser (LIBS) effectuée sur des coupes minces de tissus de rongeurs: les reins et tumorales, permet la détection des éléments inorganiques tels que (i) Na, Ca, Cu, Mg, P et Fe, naturellement présente dans le corps et (ii) Si et D.ieu, détectés après l&#39;injection de nanoparticules à base de gadolinium. Les animaux ont été euthanasiés 1 à 24 h après l&#39;injection intraveineuse de particules. Un balayage en deux dimensions de l&#39;échantillon, effectuée en utilisant un micrométrique 3D-platine motorisée, laisse le faisceau laser infrarouge à explorer la surface avec une résolution latérale inférieure à 100 μ m. Images chimique quantitative de D.ieu élément intérieur de l&#39;organe ont été obtenus avec la sensibilité sous-mM. LIBS est une méthode simple et robuste pour étudier la distribution de matériaux inorganiques sans labeli spécifiqueng. En outre, la compatibilité de l&#39;installation avec la microscopie optique standard souligne son potentiel à fournir de multiples images de la même tissu biologique avec différents types de réponse: élémentaire, moléculaires ou cellulaires.

Comme le montre la figure 1, le faisceau d&#39;un laser Nd: YAG à la longueur d&#39;onde fondamentale de 1064 nm a été concentré verticalement vers le bas sur la tranche de tissu par une lentille de quartz de 50 mm de distance focale. L&#39;énergie d&#39;impulsion était de 4 mJ et le taux de répétition de 10 Hz. Afin d&#39;éviter la génération de plasma dans l&#39;air, le faisceau laser a été focalisé autour de 100 um sous la surface de l&#39;échantillon. Pas de plasma d&#39;air a été o...

Watch this Scientific Journal Video about Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue at JoVE.com

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle&#039;s Mapping and Quantification in Organ Tissue

Spectroscopie par claquage induit par laser effectués sur organe mince et le tissu tumoral a détecté avec succès des éléments naturels et gadolinium injecté artificiellement (Gd), émises à partir de nanoparticules à base de Gd. Images d&#39;éléments chimiques ont atteint une résolution de 100 um et de la sensibilité quantitative sous-mM. La compatibilité de l&#39;installation avec la microscopie optique standard souligne son potentiel pour fournir de multiples images d&#39;un même tissu biologique.

Induite par laser Répartition Spectroscopy: Une nouvelle approche pour la cartographie et la quantification de nanoparticules dans les tissus d&#39;organes

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) ...

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Research

JoVE Journal

Engineering

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

13.6K vues.  CNRS - Université Lyon 1.  Spectroscopie par claquage induit par laser effectués sur organe mince et le tissu tumoral a détecté avec succès des éléments naturels et gadolinium injecté artificiellement (Gd), émises à partir de nanoparticules à base de Gd. Images d'éléments chimiques ont atteint une résolution de 100 um et de la sensibilité quantitative sous-mM. La compatibilité de l'installation avec la microscopie optique standard souligne son potentiel pour fournir de multi...

Vidéo: Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

Résolution angulaire spectroscopie de photoémission à très basse température

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

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Ingénierie

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Exploration et cartographie des surfaces d&#39;électrodes en piles à oxyde solide

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Scanning-probe Single-electron Capacitance Spectroscopy

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the electronic quantum structure of small systems - including individual atomic dopants in semiconductors. Here we present a capacitance-based method, known as Subsurface Charge Accumulation (SCA) imaging, which is capable of resolving single-electron charging while achieving sufficient spatial resolution to image individual atomic dopants. The use of a capacitance technique enables observation of subsurface features, such as dopants buried many nanometers beneath the surface of a semiconductor material1,2,3. In principle, this technique can be applied to any system to resolve electron motion below an insulating surface.
As in other electric-field-sensitive scanned-probe techniques4, the lateral spatial resolution of the measurement depends in part on the radius of curvature of the probe tip. Using tips with a small radius of curvature can enable spatial resolution of a few tens of nanometers. This fine spatial resolution allows investigations of small numbers (down to one) of subsurface dopants1,2. The charge resolution depends greatly on the sensitivity of the charge detection circuitry; using high electron mobility transistors (HEMT) in such circuits at cryogenic temperatures enables a sensitivity of approximately 0.01 electrons/Hz&frac12; at 0.3 K 5.

Scanning-probe single-electron capacitance spectroscopy facilitates the study of single-electron motion in localized subsurface regions. A sensitive charge-detection circuit is incorporated into a cryogenic scanning probe microscope to investigate small systems of dopant atoms beneath the surface of semiconductor samples.

Sonde à balayage spectroscopie de capacité unique électron

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the ...

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 &#181;m spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO).
The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

Time-resolved atomic and diatomic molecular species are measured using LIBS. The spectra are collected at various time delays following the generation of optical breakdown plasma with Nd:YAG laser radiation&#160;and are analyzed to infer electron density and temperature.

Mesure et analyse de l&#39;hydrogène atomique et moléculaire diatomique AlO, C<sub&gt; 2</sub&gt;, CN, et TiO Spectra après une rupture optique induite par laser

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement ...

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy

Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards understanding its mechanism. Protonation and conformational changes affect the vibration pattern of amino acid side chains and of the peptide bond, respectively, both of which can be probed by infrared (IR) difference spectroscopy. For proteins whose function can be repetitively and reproducibly triggered by light, it is possible to obtain infrared difference spectra with (sub)microsecond resolution over a broad spectral range using the step-scan Fourier transform infrared technique. With ~102-103 repetitions of the photoreaction, the minimum number to complete a scan at reasonable spectral resolution and bandwidth, the noise level in the absorption difference spectra can be as low as ~10-4, sufficient to follow the kinetics of protonation changes from a single amino acid. Lower noise levels can be accomplished by more data averaging and/or mathematical processing. The amount of protein required for optimal results is between 5-100 &#181;g, depending on the sampling technique used. Regarding additional requirements, the protein needs to be first concentrated in a low ionic strength buffer and then dried to form a film. The protein film is hydrated prior to the experiment, either with little droplets of water or under controlled atmospheric humidity. The attained hydration level (g of water / g of protein) is gauged from an IR absorption spectrum. To showcase the technique, we studied the photocycle of the light-driven proton-pump bacteriorhodopsin in its native purple membrane environment, and of the light-gated ion channel channelrhodopsin-2 solubilized in detergent.

Key steps of protein function, in particular backbone conformational changes and proton transfer reactions, often take place in the microsecond to millisecond time scale. These dynamical processes can be studied by time-resolved step-scan Fourier-transform infrared spectroscopy, in particular for proteins whose function is triggered by light.

Proton transfert et la conformation des protéines photosensibles dans la dynamique des protéines par résolution temporelle étape-scan à transformée de Fourier spectroscopie infrarouge

Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards ...

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. The aggressive scaling of feature sizes, both on devices and interconnects, leads to serious challenges to ensure the required product reliability. Standard reliability tests and post-mortem failure analysis provide only limited information about the physics of failure mechanisms and degradation kinetics. Therefore it is necessary to develop new experimental approaches and procedures to study the TDDB failure mechanisms and degradation kinetics in particular. In this paper, an in situ experimental methodology in the transmission electron microscope (TEM) is demonstrated to investigate the TDDB degradation and failure mechanisms in Cu/ULK interconnect stacks. High quality imaging and chemical analysis are used to study the kinetic process. The in situ electrical test is integrated into the TEM to provide an elevated electrical field to the dielectrics. Electron tomography is utilized to characterize the directed Cu diffusion in the insulating dielectrics. This experimental procedure opens a possibility to study the failure mechanism in interconnect stacks of microelectronic products, and it could also be extended to other structures in active devices.

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. This paper demonstrates the procedure of an in situ TDDB experiment in the transmission electron microscope, which opens a possibility to study the failure mechanism in microelectronic products.

En rupture diélectrique Situ en fonction du temps dans le microscope électronique à transmission: une possibilité de comprendre le mécanisme de panne des dispositifs microélectroniques

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. ...

Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics industry. In this technique the chip and/or the substrate is bumped and the two are bonded via these conductive bumps. Many bumping techniques have been developed and intensively investigated since the introduction of the FC technology in 19601 such as stencil printing, stud bumping, evaporation and electroless/electroplating2. Despite the progress that these methods have made they all suffer from one or more than one drawbacks that need to be addressed such as cost, complex processing steps, high processing temperatures, manufacturing time and most importantly the lack of flexibility. In this paper, we demonstrate a simple and cost-effective laser-based bump forming technique known as Laser-induced Forward Transfer (LIFT)3. Using the LIFT technique a wide range of bump materials can be printed in a single-step with great flexibility, high speed and accuracy at RT. In addition, LIFT enables the bumping and bonding down to chip-scale, which is critical for fabricating ultra-miniature circuitry.

We demonstrate the use of the Laser-induced Forward Transfer (LIFT) technique for flip-chip assembly of optoelectronic components. This approach provides a simple, cost-effective, low-temperature, fast and flexible solution for fine-pitch bumping and bonding on chip-scale for achieving high-density circuits for optoelectronic applications.

Induite par laser transfert vers l&#39;avant pour Flip-chip emballage de Dies simples

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics ...

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

Tomographie à dispersion d&#39;énergie de rayons X pour la 3D élémentaire Cartographie des nanoparticules individuelles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Détection et récupération du palladium, or et métaux de cobalt provenant de la mine urbaine utilisant de nouveaux capteurs / adsorbants désignés avec Nanoscale Wagon en forme de roues-Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Blast Quantification Using Hopkinson Pressure Bars

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures up to many hundreds of megapascals. In this respect the simplicity of the Hopkinson pressure bar has a major advantage in that while the measurement end of the Hopkinson bar can endure and be exposed to harsh conditions, the strain gauge mounted to the bar can be affixed some distance away. This allows protective housings to be utilized which protect the strain gauge but do not interfere with the measurement acquisition. The use of an array of pressure bars allows the pressure-time histories at discrete known points to be measured. This article also describes the interpolation routine used to derive pressure-time histories at un-instrumented locations on the plane of interest. Currently the technique has been used to measure loading from high explosives in free air and buried shallowly in various soils.

This protocol details the use of Hopkinson pressure bars to measure reflected blast loading from near-field explosive events. It is capable of interpolating a pressure-time history at any point on a reflective boundary and as such can be used to fully characterize the spatial and temporal variations in loading produced.

Explosion Quantification Utilisation des barres de pression Hopkinson

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures ...