Los autores reconocen al Dr. Michael J. Friedlander, Director del Virginia Tech Carilion Research Institute por alentar nuestros esfuerzos de investigación. Este proyecto fue apoyado por fondos de desarrollo para S.M.M y D.F.K. y en parte por la iniciativa Nano-Bio del Instituto de Tecnología Crítica y Ciencia Aplicada de Virginia Tech.

1. Preparar dispositivos de captura de afinidad16
<ol><li>Limpie los E-chips de nitruro de silicio incubando en 15 ml de acetona durante 2 min seguidos de 15 ml de metanol durante 2 min(Figura 1A). Deje que las virutas se sequen bajo el flujo de aire laminar.</li>
	<li>Incube las virutas secas en una placa de agitación calentada (sin agitar) durante 1,5 horas a 150 °C, luego déjenlas enfriar a temperatura ambiente antes de usarlas.</li>
	<li>Utilice jeringas Hamilton para componer mezclas de lípidos en pequeños tubos de vidrio para contener 25% de cloroformo, 55% dlpc (1,2-dilauroil-fosfocolina) en cloroformo (1 mg/ml) y 20% de lípidos de Ni-NTA (1,2-dioleoil-iminodiacéctico ácido-succinil-níquel sal) en cloroformo (1 mg/ml) para un volumen total de 40 μl.</li>
	<li>Aplicar una alícuota de 1 μl de la mezcla sobre cada gota de 15 μl de agua Milli-Q en un trozo de Parafilm en una placa de Petri húmeda (Figura 1B). Incubar muestras sobre hielo durante al menos 60 min.</li>
</ol>2. Capturar macromoléculas17
<ol><li>Coloque un E-chip con un espaciador integrado de 150 nm encima de una muestra de monocapa e incube durante 1 min (Figura 1C).</li>
	<li>Levante suavemente el chip de la muestra y agregue una alícuota de 3 μl de proteína A etiquetada por His. Incubar durante 1 minuto a temperatura ambiente (Figura 1D).</li>
	<li>Elimine el exceso de gota usando Whatman #1 papel de filtro y agregue inmediatamente una alícuota de 3 μl de solución de anticuerpos. Incubar durante 1 min a temperatura ambiente.</li>
	<li>Retire el exceso de solución con una jeringa Hamilton y agregue inmediatamente una alícuota de 1 μl de DLPs de rotavirus (0,1 mg/ml) en una solución tampón que contenga 50 mM de HEPES (pH 7,5), 150 mM de NaCl, 10 mM de MgCl2 y 10 mM de CaCl2. Incubar durante al menos 2 min a temperatura ambiente. La preparación de dlps se ha descrito previamente18.
</li>
</ol>3. Montar la cámara microfluídica y cargar el soporte de muestras in situ
<ol><li>Cargue el E-chip húmedo que contiene la muestra viral en la punta del soporte de la muestra microfluídica. Descarga incandescente de un segundo E-chip plano durante 1 min y luego cargado en la parte superior del chip espaciador(Figura 2, paneles 1-5).</li>
	<li>Alternativamente, para aumentar el contraste de las macromoléculas biológicas, se puede agregar una mancha de metal pesado(por ejemplo, formiato de uranilo al 0,2%) a los especímenes húmedos antes de colocar el segundo chip E en el espécimen húmedo. Sin embargo, el chip E que contiene la muestra deberá lavarse con agua Milli-Q antes de agregar el reactivo de contraste.</li>
	<li>Sándwich de todo el conjunto juntos para formar un recinto sellado, mantenido en su lugar mecánicamente dentro del soporte por 3 tornillos de latón(Figura 2,paneles 6-8).</li>
	<li>Después del montaje, la punta del soporte se bombea a 10-6 Torr utilizando una estación de bombeo seco turbobombada antes de colocar el soporte dentro del TEM.</li>
</ol>4. Imágenes en líquido usando un microscopio electrónico de transmisión
<ol><li>Cargue el soporte de la muestra in situ en un microscopio electrónico de transmisión (FEI Company) equipado con un filamento LaB6 y funcionando a 120 kV.</li>
	<li>Encienda el filamento TEM y ajuste la altura eucéntrica de la etapa del microscopio con respecto a la muestra utilizando la función wobbler para inclinar la muestra de -15° a +15° hacia adelante y hacia atrás en la columna. Este procedimiento ajusta la etapa en la dirección z para ayudar a tener en cuenta el espesor adecuado de la cámara de líquido. Este paso también garantiza que se utilice una ampliación precisa al grabar imágenes.</li>
	<li>Grabe primero imágenes a lo largo de los bordes y en las regiones de las esquinas de la cámara microfluídica. Estas áreas suelen contener la solución más delgada. Registre imágenes de especímenes en condiciones de dosis bajas (1-3electrones/Å 2)utilizando una cámara CCD. Utilice aumentos nominales de 6,000X - 30,000X.</li>
	<li>Determine el valor de desenfoque adecuado enfocando en el borde de la cámara fluic. Utilice un valor de -1,5 μm para grabar imágenes con un aumento de 30.000X. Si se encuentra una solución gruesa o si no se utiliza el agente de contraste en la preparación de la muestra, utilice valores de desenfoque más altos en el rango de -2 a -4 μm.</li>
	<li>Para asegurarse de que la solución está contenida en la cámara microfluídica a lo largo de los experimentos, enfoque el haz de electrones hasta que se formen las burbujas en el líquido dentro del dispositivo.</li>
</ol>

<ol>
	<li>Zhou, Z. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+atomic+resolution+structural+determination+by+single-particle+cryo-electron+microscopy.">Towards atomic resolution structural determination by single-particle cryo-electron microscopy.</a> Curr. Opin. Struct. Biol. 18, 218-228 (2008).</li><li>Wolf, M., Garcea, R. L., Grigorieff, N., Harrison, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subunit+interactions+in+bovine+papillomavirus.">Subunit interactions in bovine papillomavirus.</a> Proc. Natl. Acad. Sci. U.S.A. 107, 6298-6303 (2010).</li><li>Dubochet, J., 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=Cryo-electron+microscopy+of+vitrified+specimens.">Cryo-electron microscopy of vitrified specimens.</a> Q. Rev. Biophys. 21, 129-228 (1988).</li><li>Unwin, P. N., Henderson, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+structure+determination+by+electron+microscopy+of+unstained+crystalline+specimens.">Molecular structure determination by electron microscopy of unstained crystalline specimens.</a> J. Mol. Biol. 94, 425-440 (1975).</li><li>Ohi, M., Li, Y., Cheng, Y., Walz, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Negative Staining and Image Classification - Powerful Tools in Modern Electron Microscopy. Biol. Proced. Online. 6, 23-34 (2004).</li><li>Adrian, M., Dubochet, J., Fuller, S. D., Harris, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryo-negative+staining.">Cryo-negative staining.</a> Micron. 29, 145-160 (1998).</li><li>Parsons, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+of+wet+specimens+in+electron+microscopy.+Improved+environmental+chambers+make+it+possible+to+examine+wet+specimens+easily.">Structure of wet specimens in electron microscopy. Improved environmental chambers make it possible to examine wet specimens easily.</a> Science. 186, 407-414 (1974).</li><li>Parsons, D. F., Matricardi, V. R., Moretz, R. C., Turner, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+microscopy+and+diffraction+of+wet+unstained+and+unfixed+biological+objects.">Electron microscopy and diffraction of wet unstained and unfixed biological objects.</a> Adv. Biol. Med. Phys. 15, 161-270 (1974).</li><li>Hui, S. W., Parsons, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+diffraction+of+wet+biological+membranes.">Electron diffraction of wet biological membranes.</a> Science. 184, 77-78 (1974).</li><li>Hui, S. W., Parsons, D. F., Cowden, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+diffraction+of+wet+phospholipid+bilayers.">Electron diffraction of wet phospholipid bilayers.</a> Proc. Natl. Acad. Sci. U.S.A. 71, 5068-5072 (1974).</li><li>Ring, E. A., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+system+for+transmission+electron+microscopy.">Microfluidic system for transmission electron microscopy.</a> Microsc. Microanal. 16, 622-629 (2010).</li><li>Dukes, M. J., Ramachandra, R., Baudoin, J. P., Gray Jerome, W., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+locations+of+gold-labeled+proteins+in+a+whole+mount+eukaryotic+cell+obtained+with+3nm+precision+using+aberration-corrected+scanning+transmission+electron+microscopy.">Three-dimensional locations of gold-labeled proteins in a whole mount eukaryotic cell obtained with 3nm precision using aberration-corrected scanning transmission electron microscopy.</a> J. Struct. Biol. 174, 552-562 (2011).</li><li>Yuk, J. 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=High-resolution+EM+of+colloidal+nanocrystal+growth+using+graphene+liquid+cells.">High-resolution EM of colloidal nanocrystal growth using graphene liquid cells.</a> Science. 336, 61-64 (2012).</li><li>Peckys, D. B., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+gold+nanoparticle+uptake+in+live+cells+with+liquid+scanning+transmission+electron+microscopy.">Visualizing gold nanoparticle uptake in live cells with liquid scanning transmission electron microscopy.</a> Nano Lett. 11, 1733-1738 (2011).</li><li>Klein, K. L., Anderson, I. M., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transmission+electron+microscopy+with+a+liquid+flow+cell.">Transmission electron microscopy with a liquid flow cell.</a> J. Microsc. 242, 117-123 (2011).</li><li>Degen, K., Dukes, M., Tanner, J. R., Kelly, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+affinity+capture+devices-a+nanoscale+purification+platform+for+biological+in+situ+transmission+electron+microscopy.">The development of affinity capture devices-a nanoscale purification platform for biological in situ transmission electron microscopy.</a> Rsc. Adv. 2, 2408-2412 (2012).</li><li>Gilmore, B. L., 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=Visualizing+viral+assemblies+in+a+nanoscale+biosphere.">Visualizing viral assemblies in a nanoscale biosphere.</a> Lab Chip. 13, 216-219 (2013).</li><li>Bican, P., Cohen, J., Charpilienne, A., Scherrer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+characterization+of+bovine+rotavirus+cores.">Purification and characterization of bovine rotavirus cores.</a> J. Virol. 43, 1113-1117 (1982).</li><li>Frank, J., 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=SPIDER+and+WEB:+processing+and+visualization+of+images+in+3D+electron+microscopy+and+related+fields.">SPIDER and WEB: processing and visualization of images in 3D electron microscopy and related fields.</a> J. Struct. Biol. 116, 190-199 (1996).</li><li>Zhang, X., 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=Near-atomic+resolution+using+electron+cryomicroscopy+and+single-particle+reconstruction.">Near-atomic resolution using electron cryomicroscopy and single-particle reconstruction.</a> Proc. Natl. Acad. Sci. U.S.A. 105, 1867-1872 (2008).</li><li>Scheres, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Bayesian+view+on+cryo-EM+structure+determination.">A Bayesian view on cryo-EM structure determination.</a> J. Mol. Biol. 415, 406-418 (2012).</li><li>Kelly, D. F., Abeyrathne, P. D., Dukovski, D., Walz, 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+Affinity+Grid:+a+pre-fabricated+EM+grid+for+monolayer+purification.">The Affinity Grid: a pre-fabricated EM grid for monolayer purification.</a> J. Mol. Biol. 382, 423-433 (2008).</li></ol>

La autora, Madeline J. Dukes, es empleada de Protochips, Inc.

En nuestro trabajo presentado, empleamos el acercamiento de la captura de la afinidad a la correa rotavirus DLPs a una plataforma microfluidic. Esto permitió la proyección de imagen in situ de complejos macromoleculares en un microambiente líquido. El enfoque de captura es significativo con respecto a otras técnicas de imagen microfluídicas porque localiza especímenes biológicos a la ventana de imágenes para negar los grandes problemas difusivos que surgen al grabar imágenes en líquido....

<a href="https://app.jove.com/t/6605">This corrects</a> the article <a href="https://dx.doi.org/10.3791/50936">10.3791/50936</a>

An erratum was issued for:&#160;<a href="https://www.jove.com/t/50936">In situ TEM of Biological Assemblies in Liquid</a>. The Representative Results and References sections were&#160;updated.

Erratum: In situ TEM of Biological Assemblies in Liquid

Un objetivo común de los biólogos e ingenieros es comprender el funcionamiento interno de las máquinas moleculares. Los microscopios electrónicos de transmisión (TEMs) son instrumentos ideales para visualizar estos intrincados detalles a una resolución casi atómica1-2. Con el fin de sostener el sistema de alto vacío de un TEM, las muestras biológicas se incrustan típicamente en películas delgadas de hielo vítreo3,azúcares4,sales de metales pesados5,o alguna combinación de las mismas6. Como resultado, las imágenes de especímenes incrustados pueden revelar sólo instantáneas limitadas de procesos dinámicos.
Los primeros intentos de mantener las muestras biológicas hidratadas en cámaras líquidas ambientales fueron llevados a cabo por Parsons y sus colegas utilizando etapas de bombeo diferencial. Los patrones de difracción de electrones de cristales de catalasa no manchados se registraron con éxito a una resolución de 3 Å en un estado hidratado7-8. Además, los dominios lipídicos separados por fases podrían examinarse en membranas hidratadas de eritrocitos humanos9-10. Sin embargo, el movimiento causado por la difusión de líquido y su interferencia con el haz de electrones, dio lugar a una severa pérdida de resolución y otros experimentos con especímenes biológicos no se intentaron hasta hace poco.
Se han introducido soportes de muestras microfluídicas recientemente desarrollados que utilizan microchips semiconductores para formar una cámara ambiental microescala. Estos dispositivos pueden mantener las muestras en líquido mientras se colocan en una columna TEM11-12. Este avance técnico en la imagen TEM ha permitido a los investigadores ver, por primera vez, eventos progresivos a nivel molecular13. Nos referimos a esta nueva modalidad como "microscopía molecularin situ" ya que los experimentos ahora se pueden realizar "dentro" de la columna EM14-15. El objetivo general de este método es obtener imágenes de ensamblajes biológicos en líquido para observar sus comportamientos dinámicos a resolución nanométrica. La razón detrás de la técnica desarrollada es registrar observaciones en tiempo real y examinar las nuevas propiedades de la maquinaria biológica en solución. Esta metodología amplía el uso de los TEM para fines más amplios en biología celular y molecular12-16.
En el artículo de video actual, presentamos un protocolo completo para ensamblar y usar un soporte de muestra microfluídico disponible comercialmente. Estos soportes especializados utilizan microchips de nitruro de silicio producidos con espaciadores integrados para formar una cámara líquida que encierra volúmenes minúsculos de solución. Las ventanas delgadas y transparentes se graban en los microchips con fines de imagen12. Se demuestra el uso adecuado de un soporte microfluídico para examinar las partículas de doble capa de rotavirus simios (DLPs) en líquido utilizando un TEM. Para garantizar que los ensamblajes biológicos, como los DLPs, no se difundan rápidamente a grandes distancias durante la obtención de imágenes, empleamos el enfoque affinity capture para atarlos a la superficie de la cámara microfluídica16. Este paso de captura molecular tiene una gran ventaja sobre las técnicas alternativas para la obtención de imágenes de especímenes biológicos en líquido, ya que permite la adquisición de imágenes que se utilizarán para las rutinas de procesamiento aguas abajo. Este paso de captura utilizado en conjunción con imágenes microfluídicas es exclusivo de nuestros procedimientos17. Los lectores que emplean aplicaciones de biología estructural utilizando TEM o cámaras de imágenes microfluídicas pueden considerar el uso de técnicas de captura de afinidad cuando las observaciones dinámicas a nivel molecular son el objetivo final.

<table border="0" cellpadding="0" cellspacing="0" width="832">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="43">
			<td height="43" style="height:43px;width:237px;">E-chips, spacer chip</td>
			<td style="width:183px;">Protochips, Inc.</td>
			<td style="width:245px;">EPB-52TBD</td>
			<td style="width:167px;">400 &#956;m x 50 &#956;m window</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:237px;">E-chip, top chip</td>
			<td style="width:183px;">Protochips, Inc.</td>
			<td style="width:245px;">EPT-45W</td>
			<td style="width:167px;">400 &#956;m x 50 &#956;m window</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Ni-NTA lipid</td>
			<td style="width:183px;">Avanti Polar Lipids</td>
			<td style="width:245px;">790404P</td>
			<td style="width:167px;">Powder form</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">DLPC (12:0) lipid</td>
			<td style="width:183px;">Avanti Polar Lipids</td>
			<td style="width:245px;">850335P</td>
			<td style="width:167px;">Powder form</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Volumetric flasks&#160;</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">20-812A; 20-812C</td>
			<td style="width:167px;">1 ml; 5 ml&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Hamilton Syringes</td>
			<td style="width:183px;">Hamilton Co.</td>
			<td style="width:245px;">80300, 80400</td>
			<td style="width:167px;">1-10 &#956;l; 1-25 &#956;l</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Whatman #1 filter paper</td>
			<td style="width:183px;">Whatman</td>
			<td style="width:245px;">1001 090</td>
			<td style="width:167px;">100 pieces, 90 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glass Petri dishes</td>
			<td style="width:183px;">Corning&#160;</td>
			<td style="width:245px;">70165-101</td>
			<td style="width:167px;">100 mm x 15 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glass Pasteur pipettes</td>
			<td style="width:183px;">VWR</td>
			<td style="width:245px;">14673-010</td>
			<td style="width:167px;">14673-010</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glass culture tubes</td>
			<td style="width:183px;">VWR</td>
			<td style="width:245px;">47729-566</td>
			<td style="width:167px;">6 mm x 50 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Acetone</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">&#160;A11-1</td>
			<td style="width:167px;">1 L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Methanol</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">&#160;A412-1</td>
			<td style="width:167px;">1 L</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">Chloroform&#160;</td>
			<td style="width:183px;">Electron Microcopy Sciences</td>
			<td style="width:245px;">12550</td>
			<td style="width:167px;">100 ml&#160;</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">His-tagged Protein A</td>
			<td style="width:183px;">Abcam, Inc.</td>
			<td style="width:245px;">ab52953</td>
			<td style="width:167px;">10 mg</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">Milli-Q water system</td>
			<td style="width:183px;">EMD Millipore Corp.</td>
			<td style="width:245px;">Z00QSV001</td>
			<td style="width:167px;">Ultrapure Water</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">HEPES</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">BP310-500</td>
			<td style="width:167px;">500 g</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">Equipment&#160;</td>
			<td style="width:183px;"></td>
			<td style="width:245px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">Poseidon In situ specimen holder</td>
			<td style="width:183px;">Protochips, Inc.</td>
			<td style="width:245px;"></td>
			<td>&#160;FEI compatible</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">FEI Spirit BioTwin TEM</td>
			<td style="width:183px;">FEI Co.</td>
			<td style="width:245px;"></td>
			<td>120 kV</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">Eagle 2k HS CCD camera</td>
			<td style="width:183px;">FEI Co.</td>
			<td style="width:245px;"></td>
			<td>10&#160;&#197;/pixel sampling at 30,000X</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:237px;">Gatan 655 Dry pump station</td>
			<td style="width:183px;">Gatan, Inc.</td>
			<td style="width:245px;"></td>
			<td>Pump holder tip to 10-6&#160;range</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:237px;">PELCO easiGlow, glow discharge unit</td>
			<td style="width:183px;">Ted Pella, Inc.</td>
			<td style="width:245px;"></td>
			<td>&#160;Negative polarity mode</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Isotemp heated stir plate</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;"></td>
			<td>Heat to 150 &#186;C for 1.5 hr</td>
		</tr>
	</tbody>
</table>

in situ tem of biological assemblies in liquid

Los investigadores utilizan regularmente microscopios electrónicos de transmisión (MEE) para examinar las entidades biológicas y evaluar nuevos materiales. Aquí, describimos una aplicación adicional para estos instrumentos: ver conjuntos virales en un ambiente líquido. Este método emocionante y novedoso de visualizar estructuras biológicas utiliza un soporte de espécimen a base de microfluídicos recientemente desarrollado. Nuestro artículo en video demuestra cómo ensamblar y usar un soporte microfluídico para obtener imágenes de especímenes líquidos dentro de un TEM. En particular, utilizamos partículas de doble capa (DLPs) de rotavirus simios como nuestro sistema modelo. También se describen los pasos para recubrir la superficie de la cámara líquida con biopelículas de afinidad que atar DLPs a la ventana de visualización. Esto nos permite obtener imágenes de ensamblajes de una manera que es adecuada para la determinación de la estructura 3D. Por lo tanto, presentamos una primera visión de partículas subvirales en un ambiente líquido nativo.

Las imágenes representativas de DLPs en líquido utilizando E-chips que fueron descargados por resplandor (Figura 3A) muestran menos DLPs en un área de visualización dada, presumiblemente debido a la difusión, en comparación con los DLPs que se enriquecen en dispositivos affinity capture (Figura 3B). La adición de formiato de uranilo en la cámara de imágenes mejora el contraste de la muestra y, por lo tanto, la visibilidad de los DLPs individuales en solución(Figura 3C,<...

Watch this Scientific Journal Video about In situ TEM of Biological Assemblies in Liquid at JoVE.com

In situ TEM of Biological Assemblies in Liquid

Aquí describimos un procedimiento para obtener imágenes de complejos virales en líquido a resolución nanométrica utilizando un microscopio electrónico de transmisión.

In situ TEM de Ensamblajes Biológicos en Líquido

Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an ...

in-situ-tem-of-biological-assemblies-in-liquid

Research

JoVE Journal

Bioengineering

In situ TEM of Biological Assemblies in Liquid

9.9K vistas.  Protochips, Inc.. Aquí describimos un procedimiento para obtener imágenes de complejos virales en líquido a resolución nanométrica utilizando un microscopio electrónico de transmisión.

Video: In situ TEM of Biological Assemblies in Liquid

Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers1,2. These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer3-7. Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)1,8. Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products.
While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis9. After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity10,11. Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids12. This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites13.
Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids.

This protocol will demonstrate the extraction and analysis of free and esterified bioactive fatty acids from cells. Fatty acids are accurately quantified using stable isotope dilution, chiral liquid chromatography, electron capture atmospheric chemical ionization multiple reaction monitoring mass spectrometry (SID-LC-ECAPCI-MRM/MS).

Extracción de los lípidos celulares orientadas por dilución de isótopos estables análisis de espectrometría de cromatografía de líquidos-Mass

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including ...

Investigación

Bioingeniería

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

La cuantificación de la función diastólica por Global Análisis basado en Modelado cinemático de flujo transmitral mediante el formalismo de llenado diastólico parametrizada

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper and cystine, with either copper nanoparticles (CNPs) or copper sulfate contributing the metallic component. Synthesis is carried out in liquid under biological conditions (37 &#176;C) and the self-assembled composites form after 24 hr. Once formed, these composites are highly stable in both liquid media and in a dried form. The composites scale from the nano- to micro- range in length, and from a few microns to 25 nm in diameter. Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) demonstrated that sulfur was present in the NP-derived linear structures, while it was absent from the starting CNP material, thus confirming cystine as the source of sulfur in the final nanocomposites. During synthesis of these linear nano- and micro-composites, a diverse range of lengths of structures is formed in the synthesis vessel. Sonication of the liquid mixture after synthesis was demonstrated to assist in controlling average size of the structures by diminishing the average length with increased time of sonication. Since the formed structures are highly stable, do not agglomerate, and are formed in liquid phase, centrifugation may also be used to assist in concentrating and segregating formed composites.

Here we present a protocol to synthesize novel, high-aspect ratio biocomposites under biological conditions and in liquid media. The biocomposites scale from nanometers to micrometers in diameter and length, respectively. Copper nanoparticles (CNPs) and copper sulfate combined with cystine are the key components for the synthesis.

Generación de Scalable, metálico de alta Aspect Ratio nanocompuestos en una Biológica Medio Líquido

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper ...

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances (EPS). The EPS serves as a physical and protective scaffold that houses the bacterial cells and consists of a variety of materials that includes proteins, exopolysaccharides and DNA. The composition of the EPS may change, which remodels the mechanic properties of the biofilm to further develop or support alternative biofilm structures, such as streamers, as a response to environmental cues. Despite this, there are little quantitative descriptions on how EPS components contribute to the mechanical properties and function of biofilms. Rheology, the study of the flow of matter, is of particular relevance to biofilms as many biofilms grow in flow conditions and are constantly exposed to shear stress. It also provides measurement and insight on the spreading of the biofilm on a surface. Here, particle-tracking microrheology is used to examine the viscoelasticity and effective crosslinking roles of different matrix components in various parts of the biofilm during development. This approach allows researchers to measure mechanic properties of biofilms at the micro-scale, which might provide useful information for controlling and engineering biofilms.

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Particle-tracking microrheology investigates the viscoelasticity of materials. Here, the technique is used to determine the viscoelasticity, creep compliance and effective crosslinking roles of different matrix components of a bacterial biofilm. The matrix consists of polymeric substances secreted by the bacteria and its components determine biofilm structure and mechanical properties.

En Mapping in situ de las propiedades mecánicas de biopelículas por partículas de seguimiento Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances ...

Alternating Magnetic Field-Responsive Hybrid Gelatin Microgels for Controlled Drug Release

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of smart soft devices for biomedical applications. Although a number of magnetically-responsive drug delivery systems have demonstrated efficacies through either in vitro proof of concept studies or in vivo preclinical applications, their use in clinical settings is still limited by their insufficient biocompatibility or biodegradability. Additionally, many of the existing platforms rely on sophisticated techniques for their fabrications. We recently demonstrated the fabrication of biodegradable, gelatin-based thermo-responsive microgel by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within a three-dimensional gelatin network. In this study, we present a facile method to fabricate a biodegradable drug release platform that enables a magneto-thermally triggered drug release. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and thermo-responsive polymers within gelatin-based colloidal microgels, in conjunction with an alternating magnetic field application system.

We present a facile method to fabricate a biodegradable gelatin-based drug release platform that is magneto-thermally responsive. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and poly(N-isopropylacrylamide-co-acrylamide) within a spherical gelatin micro-network crosslinked by genipin, in conjunction with an alternating magnetic field application system.

Alternando microgeles de gelatina de campo híbrido-Responsive magnéticos para Controlled Drug Release

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of ...

A Novel Technique for Generating and Observing Chemiluminescence in a Biological Setting

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are quickly moving into the operating room. Here, we present a new approach that utilizes a technique not yet explored for intraoperative imaging: chemiluminescent imaging. This method employs a ruthenium-based chemiluminescent reporter along with a custom-built nebulizing system to produce ex vivo or in vivo images with high signal-to-noise ratios. The ruthenium-based reporter produces light following exposure to an aqueous oxidizing solution and re-reduction within the surrounding tissue. This method has allowed us to detect reporter concentrations as low as 6.9 pmol/cm2. In this work, we present a visual guide to our proof-of-concept in vivo studies involving subdermal and intravenous injections in mice. The results suggest that this technology is a promising candidate for further preclinical research and might ultimately become a useful tool in the operating room.

This protocol describes a new intraoperative imaging technique that uses a ruthenium complex as a source of chemiluminescent light emission, thereby producing high signal-to-noise ratios during in vivo imaging. Intraoperative imaging is an expanding field that could revolutionize the way that surgical procedures are performed.

Una nueva técnica para generar y Observación de quimioluminiscencia en un Contexto biológico

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are ...

Automated Robotic Liquid Handling Assembly of Modular DNA Devices

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; represented by &#34;devices&#34; created as combinations of individual genetic components. However, manual assembly of such large numbers of devices is time-intensive, error-prone, and costly. The increasing sophistication and scale of synthetic biology research necessitates an efficient, reproducible way to accommodate large-scale, complex, and high throughput device construction.
Here, a DNA assembly protocol using the Type-IIS restriction endonuclease based Modular Cloning (MoClo) technique is automated on two liquid-handling robotic platforms. Automated liquid-handling robots require careful, often times tedious optimization of pipetting parameters for liquids of different viscosities (e.g. enzymes, DNA, water, buffers), as well as explicit programming to ensure correct aspiration and dispensing of DNA parts and reagents. This makes manual script writing for complex assemblies just as problematic as manual DNA assembly, and necessitates a software tool that can automate script generation. To this end, we have developed a web-based software tool, http://mocloassembly.com, for generating combinatorial DNA device libraries from basic DNA parts uploaded as Genbank files. We provide access to the tool, and an export file from our liquid handler software which includes optimized liquid classes, labware parameters, and deck layout. All DNA parts used are available through Addgene, and their digital maps can be accessed via the Boston University BDC ICE Registry. Together, these elements provide a foundation for other organizations to automate modular cloning experiments and similar protocols.
The automated DNA assembly workflow presented here enables the repeatable, automated, high-throughput production of DNA devices, and reduces the risk of human error arising from repetitive manual pipetting. Sequencing data show the automated DNA assembly reactions generated from this workflow are ~95% correct and require as little as 4% as much hands-on time, compared to manual reaction preparation.

Here, an automated workflow to perform modular DNA &#34;device&#34; assembly using a modular cloning DNA assembly method on liquid-handling robots is presented. The protocol uses an intuitive software tool for generating liquid handler picklists for combinatorial DNA device library generation, which we demonstrate using two liquid handling platforms.

Automatizado de montaje robotizada manipulación líquido de dispositivos modulares de la DNA

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Un<em&gt; In Vitro</em&gt; Órgano Cultura Modelo Murino del disco intervertebral

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i.e., nutrients, gases, waste, etc.). The nature of the metal template allows for the easy manipulation of foam shapes (i.e., rolls or films) and for the preparation of scaffolds of different pore sizes for different cell studies while preserving the interconnected porous nature of the template. The etching process does not affect the chemistry of the elastomers, preserving their biocompatible and biodegradable nature. We show that these smectic LCEs, when grown for extensive time periods, enable the study of clinically relevant and complex tissue constructs while promoting the growth and proliferation of cells.

This study presents a methodology to prepare 3D, biodegradable, foam-like cell scaffolds based on biocompatible side-chain liquid crystal elastomers (LCEs). Confocal microscopy experiments show that foam-like LCEs allow for cell attachment, proliferation, and the spontaneous alignment of C2C12s myoblasts.

Síntesis de biocompatibles de cristal líquido de elastómero Espumas como andamios celulares para 3D espaciales Cultivos Celulares

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block ...

Electric and Magnetic Field Devices for Stimulation of Biological Tissues

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, differentiation, morphology, and molecular synthesis. However, variables such stimuli strength and stimulation times need to be considered when stimulating either cells, tissues or scaffolds. Given that EFs and MFs vary according to cellular response, it remains unclear how to build devices that generate adequate biophysical stimuli to stimulate biological samples. In fact, there is a lack of evidence regarding the calculation and distribution when biophysical stimuli are applied. This protocol is focused on the design and manufacture of devices to generate EFs and MFs and implementation of a computational methodology to predict biophysical stimuli distribution inside and outside of biological samples. The EF device was composed of two parallel stainless-steel electrodes located at the top and bottom of biological cultures. Electrodes were connected to an oscillator to generate voltages (50, 100, 150 and 200 Vp-p) at 60 kHz. The MF device was composed of a coil, which was energized with a transformer to generate a current (1 A) and voltage (6 V) at 60 Hz. A polymethyl methacrylate support was built to locate the biological cultures in the middle of the coil. The computational simulation elucidated the homogeneous distribution of EFs and MFs inside and outside of biological tissues. This computational model is a promising tool that can modify parameters such as voltages, frequencies, tissue morphologies, well plate types, electrodes and coil size to estimate the EFs and MFs to achieve a cellular response.

This protocol describes the step-by-step process to build both electrical and magnetic stimulators used to stimulate biological tissues. The protocol includes a guideline to simulate computationally electric and magnetic fields and manufacture of stimulator devices.

Dispositivos eléctricos y de campo magnético para la estimulación de tejidos biológicos

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, ...