Le soutien financier par l&#39;ERC par Advanced Investigator Grant HYMEM, par la DFG par la nanosystèmes Initiative Munich (NIM) et par la Sonderforschungsbereich (SFB1032), projet A8 est grandement appréciée. Nous sommes reconnaissants au Dr Alexander Ohlinger, le Dr Sol Carretero-Palacios et spas Nedev de soutien et de discussions fructueuses.

1. Installation expérimentale <ol><li> Utiliser un microscope en haut à droite et un champ sombre condenseur d&#39;huile avec une ouverture numérique (NA) = 1,2 pour l&#39;éclairage de champ sombre. Utilisez un objectif à immersion d&#39;eau avec un grossissement de 100X et un NA = 1,0 pour les observations de particules et le piégeage. Utilisez un objectif de l&#39;air avec un grossissement de 10X et un NA = 0,2 pour suivre le mouvement de la Nauplios. </li><li> Utilisez une configuration de pinces optiques avec un laser nm 1064 à onde continue couplée dans le microscope en haut à droite. Régler la puissance de laser du piège optique à 100 mW (mesurée avec un appareil de mesure de puissance après l&#39;objectif). </li><li> Utilisez un appareil photo à haute vitesse CMOS ou un reflex numérique unique objectif (DSLR) de la caméra pour détecter et l&#39;image du mouvement de particules d&#39;or dans le piège optique et le mouvement de la Nauplios. </li><li> Utiliser un filtre coupe-bande pour éviter que le laser de pénétrer dans l&#39;appareil. </li><li> Utiliser un wattmètre pour mesurer la puissance du laser après l&#39;objectif. </li></ol> 2. Préparation de l&#39;échantillon </p&gt; <ol><li> Pipeter une gouttelette d&#39;eau (180 ul) sur une lame de verre de microscope et la position de l&#39;échantillon sur le microscope à fond noir. </li><li> Pipeter une Nauplios à partir d&#39;un petit réservoir d&#39;eau de la goutte d&#39;eau. </li><li> Utilisation d&#39;un objectif 10X d&#39;air pour observer le mouvement de la Nauplios dans la solution et d&#39;enregistrer un flux vidéo. </li><li> Utilisation d&#39;une nanoparticule d&#39;or d&#39;un diamètre de 60 nm en tant que détecteur d&#39;observer le mouvement du fluide généré par l&#39;Nauplios. Par conséquent, ajouter 5 ul d&#39;une solution très diluée de particules dans la gouttelette d&#39;eau, de sorte que d&#39;environ une particule peut être vue dans le champ de vision avec un objectif à immersion dans l&#39;eau de 100X. </li></ol> 3. Particules Suivi Expérience <ol><li> Piège une nanoparticule d&#39;or avec la pince optique. Par conséquent, amener le laser de piégeage de 1064 nm à proximité d&#39;une nanoparticule d&#39;or qui se diffuse dans la solution en déplaçant la platine du microscope. Les forces optiques intéressantes tirent la nanoparticule d&#39;or vers le point focal du ee faisceau laser. La particule piégée est pas plus diffuse et plutôt maintient sa position. Prenez un flux vidéo de la nanoparticule piégé avec l&#39;appareil photo reflex numérique à un taux de 50 Hz pour 30 sec de cadre. </li><li> Éteignez le laser de la pince optique et libérer la nanoparticule d&#39;or du piège. </li><li> Utilisez un programme de suivi de particules à la lecture de la position de la particule d&#39;or optiquement piégé à chaque trame du flux vidéo. Une transformation de Fourier rapide (FFT) de xy-position de la particule au cours du temps montre un spectre de fréquences. NOTE: Ici, un code de programme informatique &#39;IGOR PRO&#39; auto-écrite a été utilisé pour analyser la position de centre de la particule dans le plan xy au fil du temps et de l&#39;analyse FFT. </li><li> Comme une alternative à un code IGOR auto-écrite utiliser le programme gratuit &quot;Vidéo spot Tracker» pour le suivi de la particule dans la vidéo. Utilisez le logiciel commercial «Origine» pour effectuer la transformation de Fourier des données de suivi: <ol&gt; <li> Faites glisser le fichier vidéo pour le programme ouvert »Vidéo spot Tracker. </li><li> Clic de souris sur la particule vu dans la première image du flux vidéo et une région d&#39;intérêt circulaire apparaît. </li><li> Choisissez &quot;symétrique&quot; et &quot;optimiser&quot; dans le haut commandement fenêtre d&#39;invite à optimiser le suivi de la particule. </li><li> Clic de souris &quot;exploitation forestière&quot; dans le haut commandement fenêtre d&#39;invite et choisir un dossier pour enregistrer les données. Les données de suivi seront enregistrés comme une feuille de données. </li><li> Clic de souris &quot;jeu vidéo&quot; sur la fenêtre de commande gauche du programme de suivi et de patienter jusqu&#39;à ce que tous les cadres de la vidéo sont analysés. </li><li> Fermez le programme et ouvrir la feuille de calcul des données enregistrées avec «Origine». Définissez les valeurs de colonne comme &quot;y 1&quot; et &quot;2 y&quot;. </li><li> Situé pas de temps pour chaque image vidéo comme &quot;x&quot; dans la feuille de calcul de données &#39;origine&#39;. </li><li> Mark xPosition colonne et effectuer une FFT en choisissant &quot;Analyse des données&quot; et &quot;FFT&quot; dans le haut commandement fenêtre d&#39;invite. Répétez l&#39;étape pour la colonne de la position y. </li><li> Tracer les amplitudes du signal FFT calculé en x et la direction y par rapport à la fréquence. </li></ol></li></ol> 4. Simulation numérique <ol><li> Calculer les α de polarisabilité de la particule 60 nm d&#39;or en utilisant le programme informatique «Mathematica». <ol><li> Utiliser l&#39;équation (1) pour le calcul de la polarisabilité selon Kuwata et al 16.: <img alt="Equation 1" fo:content-width="3in" src="/files/ftp_upload/51502/51502eq1.jpg" width="300" /> (1) </li><li> Définir les trois paramètres suivants dans le code de programme: la fonction diélectrique complexe dépendant de la longueur d&#39;onde de la particule d&#39;or, le rayon de la nanoparticule, et l&#39;indice de réfraction du milieu environnant. </li></ol></li><li> Utiliser la description des élecdistribution du champ trique d&#39;un faisceau gaussien focalisé selon Agayan et al 17 pour le calcul des forces optiques agissant sur ​​une particule d&#39;or de 60 nm.: <img alt="Equation 2" fo:content-width="4in" src="/files/ftp_upload/51502/51502eq2.jpg" width="500" /> (2) <ol><li> . Utilisation des équations (3) - (6) à partir de Agayan et al 17 pour calculer à la fois, et le gradient de diffusion des forces agissant sur ​​la particule: <img alt="Equation 3" fo:content-width="3.5in" src="/files/ftp_upload/51502/51502eq3.jpg" width="350" /> (3) <img alt="Equation 4" fo:content-width="3in" src="/files/ftp_upload/51502/51502eq4.jpg" width="300" /> (4) <img alt="Equation 5" fo:content-width="5in" src="/files/ftp_upload/51502/51502eq5.jpg" width="500" /> (5) <img alt="Equation 6" fo:content-width="3in" src="/files/ftp_upload/51502/51502eq6.jpg" width="300" /> (6) </li><li> Dans le code de programme, de définir les paramètres de la puissance du laser, l&#39;ouverture numérique de l&#39;objectif, et la polarisabilité complexe de la nanoparticule. </li><li> Résumer la force de gradient et la force de diffusion pour calculer la force optique totale agissant sur la particule d&#39;or dans un piège optique. </li></ol></li><li> Lancer la simulation en appuyant simultanément sur &quot;Control&quot; et &quot;Enter&quot;. </li></ol>

<ol>
	<li>Hellawell, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biological indicators of freshwater pollution and environmental management. , (1986).</li><li>Diamond, J. M., Barbour, M. T., Stribling, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+and+comparing+bioassessment+approaches+and+their+results:+A+perspective.">Characterizing and comparing bioassessment approaches and their results: A perspective.</a> Journal of the North American Benthological Society. 15, 713-727 (1996).</li><li>Carlisle, D. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+quality+of+our+Nation&#8217;s+waters&#8212;Ecological+health+in+the+Nation&#8217;s+streams,+1993&#8211;2005.">The quality of our Nation&#8217;s waters&#8212;Ecological health in the Nation&#8217;s streams, 1993&#8211;2005.</a> U.S. Geological Survey Circular. 1391, (2013).</li><li>Boxhall, G. A., Defaye, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+diversity+of+copepods+(Crustacea+Copepoda)+in+freshwater.">Global diversity of copepods (Crustacea Copepoda) in freshwater.</a> Hydrobiologia. 595 (1), 195-207 (2008).</li><li>Ferdous, Z., Muktadir, A. K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Review:+Potentiality+of+Zooplankton+as+Bioindicator.">A Review: Potentiality of Zooplankton as Bioindicator.</a> American Journal of Applied Sciences. 6 (10), 1815-1819 (2009).</li><li>Andersen Borg, C. M., Bruno, E., Ki&#248;rboe, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Kinematics+of+Swimming+and+Relocation+Jumps+in+Copepod+Nauplii.">The Kinematics of Swimming and Relocation Jumps in Copepod Nauplii.</a> PLoS ONE. 7 (10), (2012).</li><li>Gilchrist, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+and+Form+of+the+Brine+Shrimp+Artemia+Salina.">Growth and Form of the Brine Shrimp Artemia Salina.</a> Journal of Zoology. 134 (2), 221-235 (1960).</li><li>Boone, E., Baas-Becking, L. G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salt+Effects+on+Egga+and+Nauplii+of+Artemia+Salina+L.">Salt Effects on Egga and Nauplii of Artemia Salina L.</a> Journal of General Physiology. 14 (6), 453-763 (1931).</li><li>Drewes, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+investigations+of+hatching+in+brine+shrimp+cysts.">Quantitative investigations of hatching in brine shrimp cysts.</a> Association for Biology Laboratory Education. 27, 299-312 (2006).</li><li>Williams, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+of+rowing+propulsion+and+the+ontogeny+of+locomotion+in+Artemia+larvae.">A model of rowing propulsion and the ontogeny of locomotion in Artemia larvae.</a> Biological Bulletin. 187, 164-173 (1994).</li><li>Croghan, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Mechanism+of+Osmotic+Regulation+in+the+Artemia+Salina+(L.):+The+Physiology+of+the+Branchiae.">The Mechanism of Osmotic Regulation in the Artemia Salina (L.): The Physiology of the Branchiae.</a> Journal of Experimental Biology. 35, 234-242 (1958).</li><li>Ashkin, A., Dziedzic, J. M., Bjorkholm, J. E., Chu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Observation+of+a+single-beam+gradient+force+optical+trap+for+dielectric+particles.">Observation of a single-beam gradient force optical trap for dielectric particles.</a> Optics Letters. 11 (5), 288-290 (1986).</li><li>Svoboda, K., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+trapping+of+metallic+Rayleigh+particles.">Optical trapping of metallic Rayleigh particles.</a> Optics Letters. 19 (13), 930-932 (1994).</li><li>Hansen, P. M., Bhatia, V. K., Harrit, N., Oddershede, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expanding+the+Optical+Trapping+Range+of+Gold+Nanoparticles.">Expanding the Optical Trapping Range of Gold Nanoparticles.</a> Nano Letters. 5 (10), 1937-1942 (2005).</li><li>Ohlinger, A., Deak, A., Lutich, A. A., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optically+Trapped+Gold+Nanoparticle+Enables+Listening+at+the+Microscale.">Optically Trapped Gold Nanoparticle Enables Listening at the Microscale.</a> Physical Review Letters. 108 (1), (2012).</li><li>Kuwata, H., Tamaru, H., Esumi, K., Miyano, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resonant+light+scattering+particles:+Practical+analysis+beyond+Rayleigh+approximation.">Resonant light scattering particles: Practical analysis beyond Rayleigh approximation.</a> Applied Physics Letters. 83 (22), 4625-4628 (2003).</li><li>Agayan, R. R., Gittes, F., Kopelman, R., Schmidt, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+trapping+near+resonance+absorption.">Optical trapping near resonance absorption.</a> Applied Optics. 41 (12), 2318-2327 (2002).</li><li>Klar, T., Perner, M., Grosse, S., von Plessen, G., Spirkl, W., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-Plasmon+Resonances+in+Single+Metallic+Nanoparticles.">Surface-Plasmon Resonances in Single Metallic Nanoparticles.</a> Physical Review Letters. 80, 4249-4252 (1998).</li><li>Ohlinger, A., Nedev, S., Lutich, A. A., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optothermal+Escape+of+Plasmonically+Coupled+Silver+Nanoparticles+from+a+Three-Dimensional+Optical+Trap.">Optothermal Escape of Plasmonically Coupled Silver Nanoparticles from a Three-Dimensional Optical Trap.</a> Nano Letters. 11 (4), 1770-1774 (2011).</li><li>Urban, A. S., Lutich, A. A., Stefani, F. D., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+Printing+Single+Gold+Nanoparticles.+Nano+Letters.">Laser Printing Single Gold Nanoparticles. Nano Letters.</a> Nano Letters. 10 (12), 4794-4798 (2010).</li><li>Urban, A. S., Fedoru, K. M., Nedev, S., Lutich, A., Lohmueller, T., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shrink-to-fit+Plasmonic+Nanostructures.">Shrink-to-fit Plasmonic Nanostructures.</a> Advanced Optical Materials. 1 (2), 123-127 (2013).</li></ol>

Les auteurs déclarent qu&#39;ils n&#39;ont aucun intérêt financier concurrents.

Microscopie en champ sombre est un outil puissant pour la visualisation de nanoparticules d&#39;or avec des dimensions inférieures à la limite de diffraction optique, depuis la section efficace de diffusion des nanoparticules métalliques dépasse leur section géométrique (cf. figure 2A) 18. Dans une configuration de type brucelles, cette approche permet de distinguer même si seulement un seul ou plusieurs des nanoparticules d&#39;or sont piégés par le faisceau laser, car le couplage p...

évaluation de la qualité de l&#39;eau basée sur des indicateurs chimiques et biologiques est d&#39;une importance fondamentale pour mieux comprendre les conditions de l&#39;Etat et de l&#39;environnement d&#39;un écosystème aquatique 1-3. Les méthodes classiques d&#39;analyse chimique de l&#39;eau sont basées sur les propriétés organoleptiques ou la détermination des paramètres physico-chimiques. Les indicateurs biologiques, d&#39;autre part, sont des espèces animales dont la présence et la viabilité donner un aperçu sur les conditions environnementales et l&#39;effet des polluants pour un écosystème qui se produisent po exemples typiques de bio-indicateurs sont copépodes, un groupe de petits crustacés d&#39;eau, qui peut être trouvé dans presque toutes les 4,5 de l&#39;habitat de l&#39;eau. Observer l&#39;activité et la viabilité de ces espèces à partir d&#39;un échantillon d&#39;eau peut ainsi être utilisée pour obtenir des informations sur les conditions générales de l&#39;écosystème 5. Les larves de copépodes, qui sont appelés Nauplii, utilisez coups rythmiques de leurs antennes (larve possède trois paires de appendages à leur région de la tête) de nager dans l&#39;eau 6. La fréquence et l&#39;intensité de ces coups est ainsi un indicateur direct de l&#39;âge, la condition physique, et les conditions environnementales de l&#39;animal 7-10. Toutes les enquêtes sur ces spécimens sont généralement effectués avec un microscope par l&#39;observation et le comptage des coups d&#39;antenne de l&#39;Nauplii directement. En raison de leur taille (~ 100-500 um) 11, cela nécessite souvent de faire des mesures soit un par un ou de fixer un seul Nauplios à un substrat. Ici, nous démontrons une nouvelle approche pour observer l&#39;activité de copépodes larves dans les échantillons d&#39;eau à l&#39;aide d&#39;une nanoparticule d&#39;or optiquement piégé comme un détecteur ultra-sensible. Pinces optiques sont généralement utilisés par de nombreux groupes comme un outil expérimental amende à appliquer ou mesurer des forces entre les molécules jusqu&#39;à la plage de piconewton 12-14. Plus récemment, la gamme d&#39;applications pour les pinces optiques a été élargie pour observer les vibrations acoustiques et résoudrefluctuations nt en milieu liquide en surveillant le mouvement de nano-et microparticules qui sont confinés dans un piège optique 15. Les particules qui sont immergés dans un liquide sont soumis à un mouvement brownien. L&#39;intérieur d&#39;un piège optique, cependant, cette motion est partiellement atténué par une forte, induite par laser, la force de gradient. Par conséquent, la rigidité du piège optique et la localisation de la particule dans le foyer du faisceau laser peuvent être réglées par la puissance du laser. Dans le même temps, il est possible de révéler des caractéristiques concernant le potentiel de piégeage et d&#39;analyser les interactions des molécules avec la particule en surveillant le mouvement des particules en fonction du temps dans le piège. Cette approche rend possible de récupérer la fréquence, l&#39;intensité et la direction du mouvement fluidique qui est généré par un objet en mouvement dans son environnement liquide. Nous montrons comment cette idée générale peut être appliquée pour obtenir un spectre de fréquence du mouvement d&#39;un individu Nauplios sans l&#39;exigenced&#39;interférer directement avec le spécimen. Cette approche expérimentale introduit un nouveau concept général pour l&#39;observation du comportement mobiles de spécimens aquatiques d&#39;une manière très sensible. Pour les observations sur les espèces bio-indicatrices, ce qui pourrait élargir la méthodologie actuelle pour l&#39;analyse de l&#39;eau et pourrait être appliqué pour obtenir des informations sur la santé et l&#39;intégrité des écosystèmes aquatiques.

<table border="0" cellpadding="0" cellspacing="0" width="874">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Microscope Zeiss Axio Scope.A1</td>
			<td style="width:127px;">Carl Zeiss</td>
			<td style="width:201px;">490035-0012-000</td>
			<td style="width:303px;">dark field illumination</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Water objective Achroplan</td>
			<td style="width:127px;">Carl Zeiss</td>
			<td style="width:201px;">440087</td>
			<td>100x magnification, NA=1.0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Air objective Epiplan</td>
			<td style="width:127px;">Carl Zeiss</td>
			<td style="width:201px;">442934</td>
			<td>10x magnification, NA=0.2</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Dark field oil condenser</td>
			<td style="width:127px;">Carl Zeiss</td>
			<td style="width:201px;">445323</td>
			<td>NA=1.2</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:244px;">Cobolt Rumba CW 1064 nm DPSSL</td>
			<td style="width:127px;">Cobolt&#160;</td>
			<td style="width:201px;">1064-05-01-2000-500</td>
			<td>1064nm, CW, &#955;=1064nm, 2 Watt, TEM00</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:244px;">Beam expander</td>
			<td style="width:127px;">Edmund Optics</td>
			<td style="width:201px;"></td>
			<td>Part no. 1064 2-8X 64414</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">High Speed Camera Dimax HD</td>
			<td style="width:127px;">PCO. Germany</td>
			<td style="width:201px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Color Camera Canon EOS 500 D&#160;</td>
			<td style="width:127px;">Canon</td>
			<td></td>
			<td>FAQ-ID: 8201395700</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Notch filter StopLine 532/1064</td>
			<td style="width:127px;">Semrock</td>
			<td style="width:201px;">A11149-711265</td>
			<td>Part no. NF01-532U</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Water&#160;</td>
			<td style="width:127px;"></td>
			<td style="width:201px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Nauplius Artemia Salina</td>
			<td style="width:127px;"></td>
			<td style="width:201px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:244px;">Gold colloid</td>
			<td style="width:127px;">BBInternational</td>
			<td style="width:201px;">Batch 13741&#160;</td>
			<td>Diameter 60nm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">MQMie Version 3.2&#160;</td>
			<td style="width:127px;">r. Michael Quinten</td>
			<td style="width:201px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mathematica 8.0</td>
			<td style="width:127px;">Wolfram</td>
			<td style="width:201px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Comsol Multiphysics 4.0&#160;</td>
			<td style="width:127px;">COMSOL, Inc.</td>
			<td style="width:201px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

analyzing the movement of the nauplius 'artemia salina' by optical tracking of plasmonic nanoparticles

Nous montrons comment pinces optiques peuvent fournir un outil sensible pour analyser les vibrations fluidiques générées par le mouvement de petits organismes aquatiques. Une nanoparticule d&#39;or unique détenu par une pince optique est utilisé comme un capteur de quantifier le mouvement rythmique d&#39;une larve Nauplios (Artemia salina) dans un échantillon d&#39;eau. Ceci est réalisé en surveillant le déplacement dépendant de la nanoparticule piégé de temps comme une conséquence de l&#39;activité Nauplios. Une analyse de Fourier de la position de la nanoparticule obtient ainsi un spectre de fréquence qui est caractéristique pour le mouvement des espèces observées. Cette expérience démontre la capacité de cette méthode pour mesurer et caractériser l&#39;activité des petites larves aquatiques sans l&#39;obligation de les observer directement et à obtenir des informations sur la position des larves par rapport à la particule piégée. Dans l&#39;ensemble, cette approche pourrait donner un aperçu de la vitalité de certaines espèces trouvées dans un e aquatiquecosystem et pourrait élargir l&#39;éventail des méthodes classiques d&#39;analyse des échantillons d&#39;eau.

Une illustration schématique du dispositif expérimental est représenté sur la Figure 1A. Une configuration de champ foncé est nécessaire pour détecter optiquement le déplacement d&#39;une particule d&#39;or de 60 nm dans un piège optique 15. La longueur d&#39;onde de 1064 nm pour le laser de piégeage est choisie pour garantir un confinement stable du 12,14 de particules d&#39;or de détecteur. Un diviseur de faisceau dans le microscope est utilisé pour focaliser le faisc...

Watch this Scientific Journal Video about Analyzing the Movement of the Nauplius 'Artemia salina' by Optical Tracking of Plasmonic Nanoparticles at JoVE.com

Analyzing the Movement of the Nauplius &#039;Artemia salina&#039; by Optical Tracking of Plasmonic Nanoparticles

Nous utilisons suivi optique de nanoparticules plasmoniques à sonder et à caractériser les mouvements de fréquence d&#39;organismes aquatiques.

Analyser le Mouvement de la Nauplios &#39;<em&gt; Artemia salina</em&gt; &#39;Par suivi optique de plasmons de surface de nanoparticules

We demonstrate how optical tweezers may provide a sensitive tool to analyze the fluidic vibrations generated by the movement of small aquatic organisms. A ...

analyzing-movement-nauplius-artemia-salina-optical-tracking-plasmonic

Research

JoVE Journal

Engineering

Analyzing the Movement of the Nauplius 'Artemia salina' by Optical Tracking of Plasmonic Nanoparticles

10.4K vues.  Ludwig-Maximilians-Universität.  Nous utilisons suivi optique de nanoparticules plasmoniques à sonder et à caractériser les mouvements de fréquence d'organismes aquatiques. 

Vidéo: Analyzing the Movement of the Nauplius 'Artemia salina' by Optical Tracking of Plasmonic Nanoparticles

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

Les métamatériaux Fabricating aide de la méthode de tirage de fibre

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Recherche

Ingénierie

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3.
A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure.
The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.

The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.

Le piégeage optique de nanoparticules

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping ...

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Patterning via Optical Saturable Transitions - Fabrication and Characterization

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.

We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

Patterning par Transitions Optical saturable - Fabrication et caractérisation

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical ...

Experiments on Ultrasonic Lubrication Using a Piezoelectrically-assisted Tribometer and Optical Profilometer

Friction and wear are detrimental to engineered systems. Ultrasonic lubrication is achieved when the interface between two sliding surfaces is vibrated at a frequency above the acoustic range (20 kHz). As a solid-state technology, ultrasonic lubrication can be used where conventional lubricants are unfeasible or undesirable. Further, ultrasonic lubrication allows for electrical modulation of the effective friction coefficient between two sliding surfaces. This property enables adaptive systems that modify their frictional state and associated dynamic response as the operating conditions change. Surface wear can also be reduced through ultrasonic lubrication. We developed a protocol to investigate the dependence of friction force reduction and wear reduction on the linear sliding velocity between ultrasonically lubricated surfaces. A pin-on-disc tribometer was built which differs from commercial units in that a piezoelectric stack is used to vibrate the pin at 22 kHz normal to the rotating disc surface. Friction and wear metrics including effective friction force, volume loss, and surface roughness are measured without and with ultrasonic vibrations at a constant pressure of 1 to 4 MPa and three different sliding velocities: 20.3, 40.6, and 87 mm/sec. An optical profilometer is utilized to characterize the wear surfaces. The effective friction force is reduced by 62% at 20.3 mm/sec. Consistently with existing theories for ultrasonic lubrication, the percent reduction in friction force diminishes with increasing speed, down to 29% friction force reduction at 87 mm/sec. Wear reduction remains essentially constant (49%) at the three speeds considered.

We present a protocol for using a piezoelectrically-assisted tribometer and optical profilometer to investigate the dependence of ultrasonic wear and friction reduction on linear velocity, contact pressure, and surface properties.

Les expériences sur les ultrasons lubrification aide d&#39;un Tribomètre piézoélectriquement-assistée et Profilomètre optique

Friction and wear are detrimental to engineered systems. Ultrasonic lubrication is achieved when the interface between two sliding surfaces is vibrated at ...

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. The composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

Hybrid multifonctionnel Fe<sub&gt; 2</sub&gt; O<sub&gt; 3</sub&gt; -Au Nanoparticules pour Efficient chauffage plasmonique

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to ...

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

Propriétés électro-Polymer nanoparticules Exposer photothermiques

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has been attributed to statistical fluctuations in the number of photons/electrons arriving at a given nano-region arising from shot-noise (SN). The SN varies inversely to the square root of a number of photons/electrons. For a fixed dosage, the SN is larger in EUV and E-beam lithographies than for traditional (193 nm) optical lithography. Bottom-up and top-down patterning approaches are combined to minimize the effects of shot noise in nano-hole patterning. Specifically, an amino-silane surfactant self-assembles on a silicon wafer that is subsequently spin-coated with a 100 nm film of a PMMA-based E-beam photoresist. Exposure to the E-beam and the subsequent development uncover the underlying surfactant film at the bottoms of the holes. Dipping the wafer in a suspension of negatively charged, citrate-capped, 20 nm gold nanoparticles (GNP) deposits one particle per hole. The exposed positively charged surfactant film in the hole electrostatically funnels the negatively charged nanoparticle to the center of an exposed hole, which permanently fixes the positional registry. Next, by heating near the glass transition temperature of the photoresist polymer, the photoresist film reflows and engulfs the nanoparticles. This process erases the holes affected by SN but leaves the deposited GNPs locked in place by strong electrostatic binding. Treatment with oxygen plasma exposes the GNPs by etching a thin layer of the photoresist. Wet-etching the exposed GNPs with a solution of I2/KI yields uniform holes located at the center of indentations patterned by E-beam lithography. The experiments presented show that the approach reduces the variation in the size of the holes caused by SN from 35% to below 10%. The method extends the patterning limits of transistor contact holes to below 20 nm.

Uniformly sized nanoparticles can remove fluctuations in contact hole dimensions patterned in poly(methyl methacrylate) (PMMA) photoresist films by electron beam (E-beam) lithography. The process involves electrostatic funneling to center and deposit nanoparticles in contact holes, followed by photoresist reflow and plasma- and wet-etching steps.

Utilisation de sacrificielles Nanoparticules pour éliminer les effets de Shot-bruit dans les trous de contact fabriquées par E-beam Lithography

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

Plasmonique et Piégeage Libération de Nanoparticules dans un environnement de surveillance

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture &#8211; information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization backend), as well as the workflow of imaging flow cytometry based on ATOM, using human cells and micro-algae as the examples.

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy ATOM

This protocol describes the implementation of an asymmetric-detection time-stretch optical microscopy system for single-cell imaging in ultrafast microfluidic flow and its applications in imaging flow cytometry.

Cytométrie de flux d&#39;imagerie microfluidique par détection asymétrique Microscopie optique à temps-étirement (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the ...