Name: gold nanorod-assisted optical stimulation of neuronal cells
Uploaded: 2015-04-27T14:00:00.000+00:00
Duration: 9 min 31 s
Description: Watch this Scientific Journal Video about Gold Nanorod-assisted Optical Stimulation of Neuronal Cells at JoVE.com

Los autores desean reconocer NanoVentures Australia para el apoyo financiero de viajes y el Prof. John Haycock por haber acogido parcialmente esta investigación en la Universidad de Sheffield y la Sra Jaimee Mayne por su ayuda durante el rodaje.

1. Preparación Au rupias Nota: Au NR se puede sintetizar por una serie de recetas 16, o comprados de vendedores comerciales. <ol><li> Medir la densidad óptica inicial (OD) de la solución de Au NR través de espectroscopía de UV-Vis, mediante el registro de los valores de absorción de 300 nm a 1000 nm con una resolución de 0,5-2 nm. Variar el volumen de la solución a ser utilizado con la cubeta disponible. </li><li> Evaluar la concentración molar inicial NP con una técnica 17 adecuado (por ejemplo, la espectroscopia UV-Vis, partícula única espectrometría de masas con plasma acoplado inductivamente, microscopía electrónica de transmisión) o utilizar los valores de concentración proporcionados por el vendedor. </li><li> Preparar una solución madre de 5 ml por dilución de la muestra inicial Au NR llegar a un OD = 1. Para el mejor repetibilidad, mantener constante la OD para todas las muestras ensayadas. Siga el protocolo del proveedor comercial para la composición del disolvente de dilución. Si no está seguro, Use agua destilada. </li><li> Centrifugar 1 ml de la solución de Au NR dos veces durante 15 minutos a 7800 xg para eliminar cualquier exceso de sustancia química de la solución. Ciclos de centrifugación pueden variar en fuerza y el tiempo (por ejemplo, 20 min a 5600 × g) 18. </li><li> Eliminar el sobrenadante y volver a suspender los NR en agua desionizada. Como partículas resuspendidas podrían formar agregados en solución, prepararlos diariamente para tener los mejores resultados. Alternativamente, almacenar en un refrigerador por no más de 1 semana. No lo congele. </li><li> Antes de usar en condiciones de cultivo celular, sonicar la solución Au NR durante 5 min y luego esterilizar con luz UV durante 30 min (intensidad de la radiación UV no menos de 400 mW ∙ m -2 a 254 nm). </li></ol> 2. NG108-15 célula neuronal Línea Cultura y Diferenciación <ol><li> Para el medio de cultivo celular, preparar 500 ml de medio estéril de Dulbecco modificado Eagle (DMEM) que contiene 10% (w / v) de suero de ternera fetal (FCS), 1% (w / v) L-glutamina, 1%(W / v) de penicilina / estreptomicina y 0,5% (w / v) de anfotericina B. Nota: Los suplementos pueden ser alicuotaron, almacenado a -20 ° C y se añaden a los medios de comunicación en el día requerido. Medio de cultivo celular se puede refrigerar en una condición estéril para un máximo de 1 mes. </li><li> Para el medio de diferenciación celular, preparar 50 ml de DMEM estéril que contenía 1% (w / v) L-glutamina, 1% (w / v) de penicilina / estreptomicina y 0,5% (w / v) de anfotericina B. </li><li> Crecer NG108-15 células neuronales en 10 ml de medio de cultivo de células en matraces T75 de poliestireno en una incubadora con atmósfera humidificada (5% de CO2 a 37 ° C). Normalmente, las semillas 1.5-2 × 10 5 células de cada matraz para estar listo en 3-4 días. Cambio de medio de cultivo de células cada dos días. Nota: Para evitar derivas genéticas o variación, no utilice células mayores de paso 21 para los experimentos. </li><li> Cuando el 70-80% de confluencia en la cultura, cambie el medio con una cálida medio de cultivo celular fresco. Mecánicamente separar las células suavemente knocrey el fondo del matraz confluente. No utilice la tripsina. </li><li> Centrifugar la suspensión celular durante 5 min a 600 xg y volver a suspender el sedimento celular en 2 ml de medio de diferenciación celular caliente. </li><li> Seed 2 × 10 4 células / cm 2 en una placa de cultivo de tejidos de poliestireno de 96 con 200 l de medio de diferenciación celular. Incubar el experimento durante 1 día a 5% de CO 2/37 ° C. </li><li> Añadir entre 3,2 × 10 9 -4,2 × 1 0 10 partículas / ml de solución de Au NR en el día 2 y se incuba durante 24 h adicionales. No agregue las partículas para los experimentos de control. Nota: A modo de control alternativo, Au NPs con una longitud de onda de absorción máxima bien diferenciado puede ser utilizado para propósitos de comparación 14. Para un comportamiento celular más consistente, mantener la densidad celular constante y de no modificar la superficie bien antes de la siembra de células. </li></ol> 3. neuritas Enhancement <ol><li> Parejael láser con una fibra óptica monomodo (apertura numérica = 0,13) y terminar con un conector de fibra (FC conectores son convenientes y comúnmente disponibles). Medir la potencia del láser de salida con un medidor de potencia estándar. Para obtener los resultados más eficaces, que coincida con la longitud de onda máxima del láser al pico de resonancia de plasmón de los NR. </li><li> En el día 3 después de la incubación NR, fijar el conector FC al pozo. Irradiar muestras y los controles a TA durante 1 min en onda continua, para diferentes potencias de láser. Deje que la cultura de proceder durante 3 días adicionales en el 5% de CO 2/37 ° C. Repetir la irradiación con láser durante un mínimo de 3 mediciones independientes. Nota: Los diferentes tiempos de irradiación y frecuencias de impulsos se pueden seleccionar, dependiendo de la aplicación. </li><li> Caracterizar el láser en términos de diámetro del haz y la irradiación láser (W ∙ cm -2). <ol><li> Para una fibra monomodo estándar, utilice NA = n ∙ pecado θ,donde n es el índice de refracción del medio en el uso y θ es el medio-ángulo del cono de luz que sale de la fibra (ver Figura 1A). De trigonometría, r = tan θ ∙ d, donde r es el radio del haz y d es la distancia entre la fibra y la muestra. El conector FC coincida con el diámetro del pozo, por lo tanto, la iluminación de la muestra a una distancia d = 2,70 ± 0,20 mm. Luz sale de la fibra en el agua (n = 1.33), lo que r = tan (sin-1 (NA / n)) ∙ d. </li><li> Usando la última ecuación, calcular el radio del haz láser, el área del haz correspondiente y la irradiancia media de láser (láser de potencia dividida por el área del haz) en el objetivo (véase el ejemplo gráfico de la Figura 1B). Estos valores representan la irradiancia media de la zona iluminada. </li><li> Evaluar los errores de las mediciones con la teoría general de la propagación de errores. Nota: La distancia bntre el conector FC y la muestra se pueden medir por las fotografías de la disposición experimental y post-procesamiento de la imagen utilizando el software apropiado (por ejemplo ImageJ). </li></ol></li><li> En el día 5, retire medio de diferenciación celular a partir de los experimentos y fijar las muestras con 3,7% (v / v), solución de formaldehído durante 10 min, a continuación, permeabilizar las células con 0,1% (v / v) de Triton X-100 durante 20 min. </li><li> Añadir 3% (w / v) de albúmina de suero bovino (BSA) a las muestras durante 60 minutos para bloquear los sitios de unión de proteína sin reaccionar. Etiquetar las muestras durante la noche anti-βIII-tubulina (5 mg / ml en PBS suplementado con 1% de BSA) a 4 ° C. </li><li> Se incuban las células durante 90 min en la oscuridad con un anticuerpo secundario apropiado (ratón anti-anticuerpo conjugado con TRITC por ejemplo IgG) utilizando una concentración de 0,4-2 mg / ml en 1% de BSA en PBS. Etiquetar los núcleos celulares con DAPI (0,1 mg / ml en agua desionizada) durante 10 min. Nota: la conjugación de anticuerpos y MIG concentraciónht puede variar de acuerdo con el protocolo de empresa. Lávese las muestras con PBS dos veces durante 5 minutos después de cada etapa de tinción. <img alt="Figura 1" src="/files/ftp_upload/52566/52566fig1.jpg" /></li><li> Muestras Imagen de epifluorescencia o microscopía confocal utilizando al menos un 20 × objetivo. Elige el microscopio filtra en consecuencia para el anticuerpo secundario. Seleccionar un filtro DAPI (λ EX = 358 nm; EM λ = 488 nm) para visualizar los núcleos celulares. </li><li> Analizar las imágenes mediante la evaluación de: i) la longitud de las neuritas máximo (registro de la longitud desde la punta de la neurita hasta el comienzo del cuerpo celular), ii) el número de neuritas por célula neuronal (resumir todas las neuritas por célula) y iii) el porcentaje de células con neuritas (dividir el número total de células que expresan βIII-tubulina por el número total de células con un núcleo con tinción positiva) 19. </li></ol> Inducida por láser 4. intracelular de Ca2 + Imaging <ol&gt; <li> Preparar un 20% (w / v) solución madre de Pluronic F-127 por disolución de 2 g de soluto en 10 ml de sulfóxido de dimetilo anhidro (DMSO). Calentar la solución de Pluronic F-127 a 40 ° C durante aproximadamente 20 min para aumentar la solubilidad. Preparar con antelación si se almacena a temperatura ambiente. </li><li> En el día 3 después de la incubación NR, preparar una solución salina equilibrada (BSS; NaCl 135 mM, 4,5 mM KCl, 1,5 mM CaCl 2, 0,5 mM MgCl 2, glucosa 5,6 mM, y HEPES 10 mM, pH 7,4) y suplementado con 5 M de Fluo-4 a.m. en DMSO y 0,1% (w / v) de Pluronic F-127 solución. Nota: La solución de BSS puede ser preparado de antemano y se refrigeró durante un máximo de 1 mes. Añadir los suplementos (Fluo-4 de la mañana y Pluronic F-127) en el día del experimento. </li><li> Retire medio de diferenciación celular y reemplazarla con la solución BSS complementado. Para obtener los mejores resultados con un microscopio confocal invertido, incubar las células en un micro-pocillos del portaobjetos. </li><li> Cargar NG108-15 células con Fluo-04 a.m.durante 30 minutos en la oscuridad a 5% de CO 2/37 ° C. Tras el tiempo de incubación, lavar las muestras dos veces con BSS para eliminar cualquier fluoróforo descargada extracelular. </li><li> Pareja el láser con una fibra óptica monomodo y escindir la punta usando técnicas estándar. Observar la punta resultante bajo un microscopio óptico, para asegurar una superficie de alta calidad (es decir, la punta debe ser perpendicular al eje de la fibra y plana después de una inspección microscopía). <ol><li> Medir la potencia del láser de salida con un medidor de potencia estándar. Inserte la fibra de distribución de luz en un soporte de fibra óptica y pegarla en un microposicionador. Consulte Brown et al. 20 para más detalles sobre la preparación de la fibra óptica y posicionamiento. Precaución: Siga las normas generales de seguridad del láser durante la medición de la potencia del láser (por ejemplo, no mire directamente al rayo láser, Usar gafas de protección láser durante la manipulación, evitar la exposición a la luz parásita otros usuarios del laboratorio) &lt;./ Li&gt; </ol></li><li> Conectar un osciloscopio al láser portátil para controlar la modulación óptica. Utilice una señal binaria con frecuencias variables (0,5-2 Hz) y longitudes de pulso (20-100 ms). Conecte el láser utilizando la señal de modulación como la lógica transistor-transistor (TTL) de entrada para el microscopio, a raíz de la configuración se muestra en Paviolo et al. 13. <ol><li> Colocar las células bajo un microscopio confocal invertido y la posición de la fibra de suministro de luz 250 ± 50 m de distancia de la célula diana en el modo de iluminación de transmisión. A esta distancia, utilizar las ecuaciones presentadas en 3.3.1 para calcular el radio del haz en el blanco. </li></ol></li><li> Usa un láser de iones de argón (488 nm) para excitar el Fluo-4 a.m. colorante internalizado (λ EX = 494 nm; λ EM = 516 nm) y la LD sincronizado para la excitación de los NR endocitosis. Realice la imagen a RT de muestras y controles utilizando al menos un objetivo de 40 × recogiendo las exploraciones de series de tiempocon 256 x 256 píxeles / resolución de fotograma en el modo de ida y vuelta con una frecuencia de al menos 4 Hz. Realice una grabación sin ninguna excitación LD para identificar cualquier interferencia láser de argón-ion (ruido de línea de base). </li><li> Quitar el fondo de los datos utilizando algoritmos penalizados mínimos cuadrados ponderados de forma adaptativa 21. Representar gráficamente los inducidos Ca 2+ variaciones como una función del tiempo. Analizar los picos transitorios en la intensidad de fluorescencia con software de post-procesamiento por umbral en un nivel tres veces la desviación estándar del ruido de línea de base (3σ). </li></ol>

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	<li>Richter, C. P., Matic, A. I., Wells, J. D., Jansen, E. D., Walsh, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+stimulation+with+optical+radiation.">Neural stimulation with optical radiation.</a> Laser. Photonics Rev. 5 (1), 68-80 (2011).</li><li>Dittami, G. M., Rajguru, S. M., Lasher, R. A., Hitchcock, R. W., Rabbitt, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+calcium+transients+evoked+by+pulsed+infrared+radiation+in+neonatal+cardiomyocytes.">Intracellular calcium transients evoked by pulsed infrared radiation in neonatal cardiomyocytes.</a> J. Physiol. 589 (6), 1295-1306 (2011).</li><li>Thompson, A. C., Wade, S. A., Brown, W. G. A., Stoddart, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+of+light+absorption+in+tissue+during+infrared+neural+stimulation.">Modeling of light absorption in tissue during infrared neural stimulation.</a> J. Biomed. Opt. 17 (7), 075002-075002 (2012).</li><li>Thompson, A. C., Wade, S. A., Cadusch, P. J., Brown, W. G., Stoddart, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+of+the+temporal+effects+of+heating+during+infrared+neural+stimulation.">Modeling of the temporal effects of heating during infrared neural stimulation.</a> J. Biomed. Opt. 18 (3), 035004 (2013).</li><li>Huang, H., Delikanli, S., Zeng, H., Ferkey, D. M., Pralle, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+control+of+ion+channels+and+neurons+through+magnetic-field+heating+of+nanoparticles.">Remote control of ion channels and neurons through magnetic-field heating of nanoparticles.</a> Nat. Nanotechnol. 5 (8), 602-606 (2010).</li><li>Farah, N., 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=Holographically+patterned+activation+using+photo-absorber+induced+neural-thermal+stimulation.">Holographically patterned activation using photo-absorber induced neural-thermal stimulation.</a> J. Neural. Eng. 10 (5), (2013).</li><li>Ciofani, G., 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=Enhancement+of+neurite+outgrowth+in+neuronal-like+cells+following+boron+nitride+nanotube-mediated+stimulation.">Enhancement of neurite outgrowth in neuronal-like cells following boron nitride nanotube-mediated stimulation.</a> ACS Nano. 4 (10), 6267-6277 (2010).</li><li>Kim, J. A., 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=Enhancement+of+neurite+outgrowth+in+PC12+cells+by+iron+oxide+nanoparticles.">Enhancement of neurite outgrowth in PC12 cells by iron oxide nanoparticles.</a> Biomaterials. 32 (11), 2871-2877 (2011).</li><li>Myroshnychenko, V., 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=Modelling+the+optical+response+of+gold+nanoparticles.">Modelling the optical response of gold nanoparticles.</a> Chem. Soc. Rev. 37 (9), 1792-1805 (2008).</li><li>Choi, W. I., Sahu, A., Kim, Y. H., Tae, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photothermal+cancer+therapy+and+imaging+based+on+gold+nanorods.">Photothermal cancer therapy and imaging based on gold nanorods.</a> Ann. Biomed. Eng. 40 (2), 534-546 (2011).</li><li>Zhan, Q., Qian, J., Li, X., He, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+study+of+mesoporous+silica-encapsulated+gold+nanorods+as+enhanced+light+scattering+probes+for+cancer+cell+imaging.">A study of mesoporous silica-encapsulated gold nanorods as enhanced light scattering probes for cancer cell imaging.</a> Nanotechnology. 21 (5), 055704 (2010).</li><li>Paviolo, C., 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=Laser+exposure+of+gold+nanorods+can+increase+neuronal+cell+outgrowth.">Laser exposure of gold nanorods can increase neuronal cell outgrowth.</a> Biotechnol. Bioeng. 110 (8), 2277-2291 (2013).</li><li>Paviolo, C., Haycock, J. W., Cadusch, P. J., McArthur, S. L., Stoddart, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+exposure+of+gold+nanorods+can+induce+intracellular+calcium+transients.">Laser exposure of gold nanorods can induce intracellular calcium transients.</a> J. Biophotonics. 7 (10), 761-765 (2014).</li><li>Yong, 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=Gold-nanorod-assisted+near-infrared+stimulation+of+primary+auditory+neurons.">Gold-nanorod-assisted near-infrared stimulation of primary auditory neurons.</a> Adv. Healthcare Mater. , (2014).</li><li>Eom, K., 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=Enhanced+infrared+neural+stimulation+using+localized+surface+plasmon+resonance+of+gold+nanorods.">Enhanced infrared neural stimulation using localized surface plasmon resonance of gold nanorods.</a> Small. , (2014).</li><li>Juste, J., Pastoriza-Santos, I., Liz-Marz&#225;n, L. M., Mulvaney, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanorods:+Synthesis,+characterization+and+applications.">Gold nanorods: Synthesis, characterization and applications.</a> Coordination Chemistry Reviews. (17-18), 1870-1901 (2005).</li><li>Shang, J., Gao, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+counting:+towards+accurate+determination+of+the+molar+concentration.">Nanoparticle counting: towards accurate determination of the molar concentration.</a> Chem. Soc. Rev. 43 (21), 7267-7278 (2014).</li><li>Sharma, V., Park, K., Srinivasarao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+separation+of+gold+nanorods+using+centrifugation.">Shape separation of gold nanorods using centrifugation.</a> Proc. Natl. Acad. Sci. 106 (13), 4981-4985 (2009).</li><li>Kaewkhaw, R., Scutt, A. M., Haycock, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+site+influences+the+differentiation+of+adipose-derived+stem+cells+for+schwann-cell+phenotype+and+function.">Anatomical site influences the differentiation of adipose-derived stem cells for schwann-cell phenotype and function.</a> Glia. 59 (5), 734-749 (2011).</li><li>Brown, W. G. A., Needham, K., Nayagam, B. A., Stoddart, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+cell+patch+clamp+for+investigating+the+mechanisms+of+infrared+neural+stimulation.">Whole cell patch clamp for investigating the mechanisms of infrared neural stimulation.</a> JoVE. (77), (2013).</li><li>Cadusch, P. J., Hlaing, M. M., Wade, S. A., McArthur, S. L., Stoddart, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+methods+for+fluorescence+background+subtraction+from+Raman+spectra.">Improved methods for fluorescence background subtraction from Raman spectra.</a> J. Raman Spectrosc. 44 (11), 1587-1595 (2013).</li><li>Daud, M. F. B., Pawar, K. C., Claeyssens, F., Ryan, A. J., Haycock, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+aligned+3D+neuronal-glial+co-culture+model+for+peripheral+nerve+studies.">An aligned 3D neuronal-glial co-culture model for peripheral nerve studies.</a> Biomaterials. 33 (25), 5901-5913 (2012).</li><li>Jung, S., 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=Intracellular+gold+nanoparticles+increase+neuronal+excitability+and+aggravate+seizure+activity+in+the+mouse+brain.">Intracellular gold nanoparticles increase neuronal excitability and aggravate seizure activity in the mouse brain.</a> PLoS ONE. 9 (3), e91360 (2014).</li><li>Salinas, K., Kereselidze, Z., DeLuna, F., Peralta, X., Santamaria, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transient+extracellular+application+of+gold+nanostars+increases+hippocampal+neuronal+activity.">Transient extracellular application of gold nanostars increases hippocampal neuronal activity.</a> J. Nanobiotechnology. 12 (1), 31 (2014).</li><li>Ebbesen, C. L., Bruus, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+laser-induced+heating+in+optical+neuronal+guidance.">Analysis of laser-induced heating in optical neuronal guidance.</a> J. Neurosci. Meth. 209 (1), 168-177 (2012).</li><li>Iwanaga, S., 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=Location-dependent+photogeneration+of+calcium+waves+in+HeLa+cells.">Location-dependent photogeneration of calcium waves in HeLa cells.</a> Cell Biochem. Biophys. 45 (2), 167-176 (2006).</li><li>Huang, X., Jain, P. K., El-Sayed, I. H., El-Sayed, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+the+minimum+temperature+required+for+selective+photothermal+destruction+of+cancer+cells+with+the+use+of+immunotargeted+gold+nanoparticles.">Determination of the minimum temperature required for selective photothermal destruction of cancer cells with the use of immunotargeted gold nanoparticles.</a> Photochem. Photobiol. 82 (2), 412-417 (2006).</li><li>Connor, E. E., Mwamuka, J., Gole, A., Murphy, C. J., Wyatt, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanoparticles+are+taken+up+by+human+cells+but+do+not+cause+acute+cytotoxicity.">Gold nanoparticles are taken up by human cells but do not cause acute cytotoxicity.</a> Small. 1 (3), 325-327 (2005).</li><li>Isomaa, B., Reuter, J., Djupsund, 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=The+subacute+and+chronic+toxicity+of+cetyltrimethylammonium+bromide+(CTAB),+a+cationic+surfactant,+in+the+rat.">The subacute and chronic toxicity of cetyltrimethylammonium bromide (CTAB), a cationic surfactant, in the rat.</a> Arch. Toxicol. 35 (2), 91-96 (1976).</li><li>Juste, J., Pastoriza-Santos, I., Liz-Marz&#225;n, L., Mulvaney, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanorods:+synthesis,+characterization+and+applications.">Gold nanorods: synthesis, characterization and applications.</a> Coord. Chem. Rev. 249 (17-18), 1870-1901 (2005).</li><li>Dreaden, E. C., Alkilany, A. M., Huang, X., Murphy, C. J., El-Sayed, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+golden+age:+gold+nanoparticles+for+biomedicine.">The golden age: gold nanoparticles for biomedicine.</a> Chem. Soc. Rev. 41 (7), 2740-2779 (2012).</li><li>Huang, X., Jain, P. K., El-Sayed, I. H., El-Sayed, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmonic+photothermal+therapy+(PPTT)+using+gold+nanoparticles.">Plasmonic photothermal therapy (PPTT) using gold nanoparticles.</a> Lasers Med. Sci. 23 (3), 217-228 (2008).</li><li>Albert, E. S., 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=TRPV4+channels+mediate+the+infrared+laser-evoked+response+in+sensory+neurons.">TRPV4 channels mediate the infrared laser-evoked response in sensory neurons.</a> J. Neurophysiol. 107 (12), 3227-3234 (2012).</li><li>Garcia-Elias, A., 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=Phosphatidylinositol-4,5-biphosphate-dependent+rearrangement+of+TRPV4+cytosolic+tails+enables+channel+activation+by+physiological+stimuli.">Phosphatidylinositol-4,5-biphosphate-dependent rearrangement of TRPV4 cytosolic tails enables channel activation by physiological stimuli.</a> Proceedings of the National Academy of Sciences of the United States of America. 110 (23), 9553-9558 (2013).</li><li>Shapiro, M. G., Homma, K., Villarreal, S., Richter, C. -. P., Bezanilla, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+light+excites+cells+by+changing+their+electrical+capacitance.">Infrared light excites cells by changing their electrical capacitance.</a> Nat. Commun. 3 (736), (2012).</li><li>Roggan, A., Friebel, M., D&#246;rschel, K., Hahn, A., M&#252;ller, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+properties+of+circulating+human+blood+in+the+wavelength+range+400-2500+nm.">Optical properties of circulating human blood in the wavelength range 400-2500 nm.</a> J. Biomed. Opt. 4 (1), 36-46 (1999).</li><li>Byrnes, K. R., 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=Light+promotes+regeneration+and+functional+recovery+and+alters+the+immune+response+after+spinal+cord+injury.">Light promotes regeneration and functional recovery and alters the immune response after spinal cord injury.</a> Lasers Surg. Med. 36 (3), 171-185 (2005).</li><li>Wu, 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=810+nm+wavelength+light:+an+effective+therapy+for+transected+or+contused+rat+spinal+cord.">810 nm wavelength light: an effective therapy for transected or contused rat spinal cord.</a> Lasers Surg. Med. 41 (1), 36-41 (2009).</li><li>Grossman, N., Schneid, N., Reuveni, H., Halevy, S., Lubart, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=780+nm+low+power+diode+laser+irradiation+stimulates+proliferation+of+keratinocyte+cultures:+involvement+of+reactive+oxygen+species.">780 nm low power diode laser irradiation stimulates proliferation of keratinocyte cultures: involvement of reactive oxygen species.</a> Lasers Surg. Med. 22 (4), 212-218 (1998).</li><li>Wong-Riley, M. T. T., 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=Photobiomodulation+directly+benefits+primary+neurons+functionally+inactivated+by+toxins+-+Role+of+cytochrome+c+oxidase.">Photobiomodulation directly benefits primary neurons functionally inactivated by toxins - Role of cytochrome c oxidase.</a> J. Biol. Chem. 280 (6), 4761-4771 (2005).</li><li>Beauvoit, B., Kitai, T., Chance, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+the+mitochondrial+compartment+to+the+optical+properties+pf+the+rat+liver:+a+theoretical+and+practical+approach.">Contribution of the mitochondrial compartment to the optical properties pf the rat liver: a theoretical and practical approach.</a> Biophys. J. 67 (6), 2501-2510 (1994).</li></ol>

The authors have no competing interests to disclose.

Los protocolos descritos en esta presentación se describe cómo la cultura, diferenciar y ópticamente a estimular las células neuronales utilizando absorbentes extrínsecos. Las características NR (por ejemplo, dimensiones, forma, longitud de onda de resonancia de plasmón y química de la superficie) y los parámetros de estimulación láser (tales como longitud de onda, longitud de pulso, frecuencia de repetición, etc.) se pueden variar para que coincida con diferentes necesidades experimentales...

Estudios recientes han demostrado que el calentamiento transitorio asociado con la absorción de luz infrarroja por el agua (longitud de onda&gt; 1400 nm) se puede utilizar para inducir potenciales de acción en el tejido nervioso 1 y transitorios de calcio intracelular en cardiomiocitos 2. El uso de luz infrarroja ha planteado un gran interés para aplicaciones en prótesis neurales, debido al potencial de resolución espacial más fina, la falta de contacto directo con el tejido, la reducción al mínimo de artefactos de estimulación, y la eliminación de la necesidad de modificar genéticamente las células antes de la estimulación ( como se requiere en la optogenética) 1. A pesar de todos estos beneficios, modelos térmicos desarrollados recientemente sugirieron que los tejidos / células diana pueden verse afectados por efectos de calentamiento y acumulativos, cuando se utilizan múltiples sitios de estímulo y / o altas tasas de repetición 3,4. En respuesta a estos desafíos, los investigadores han reconocido el potencial de utilizar ABSOR extrínsecabros de la estimulación del nervio para producir efectos de calentamiento más localizadas en el tejido. Huang et al. Demostró este principio mediante el uso de nanopartículas de ferrita superparamagnéticas para activar remotamente los canales TRPV1 sensibles a la temperatura en las células HEK 293 con una radio-frecuencia del campo magnético 5. Aunque esta técnica puede permitir una penetración más profunda (campos magnéticos interactúan relativamente débilmente con el tejido), las respuestas sólo se registraron durante períodos de segundos, en lugar de las duraciones de milisegundos requeridos en los dispositivos biónicos 5. Del mismo modo, Farah et al. Estimulación eléctrica demostrada de neuronas corticales de rata con micro-partículas negras en vitro. Mostraron precisión a nivel celular en la estimulación utilizando duraciones de pulso del orden de cientos de microsegundo y energías en el rango de mu J, permitiendo potencialmente las tasas de repetición más rápidas 6. El uso de absorbentes de extrínsecos también se ha aplicado para inducircambios morfológicos in vitro. Ciofani et al. Mostraron un aumento de ~ 40% en el crecimiento externo celular neuronal utilizando piezoeléctricos nitruro de boro nanotubos excitados por ultrasonido 7. Del mismo modo, se ha informado de nanopartículas de óxido de hierro endocitosis en las células PC12 para mejorar la diferenciación de neuritas en una manera dependiente de la dosis, debido a la activación de moléculas de adhesión celular con el óxido de hierro 8. Recientemente, el interés en absorbedores extrínsecos para ayudar a la estimulación neural también se ha centrado en el uso de nanopartículas de oro (Au NPs). Au NPs tienen la capacidad de absorber de manera eficiente la luz láser en el pico plasmónica y para disipar en el ambiente circundante en forma de calor 9. Entre todas las formas de las partículas disponibles, la absorción óptica de nanorods oro (Au NRS) convenientemente coincide con la ventana terapéutica de tejidos biológicos (infrarrojo cercano - NIR, longitud de onda entre 750-1,400 nm) 10. Además, en el context de estimulación neural, el uso de Au NR proporciona biocompatibilidad relativamente favorable y una amplia gama de opciones de funcionalización de la superficie 11. Estudios recientes han demostrado que un efecto estimulador en la diferenciación puede ser inducida después de exposiciones láser continuo de Au NR en NG108-15 células neuronales 12. Del mismo modo, los transitorios de calcio intracelulares se registraron en las células neuronales cultivadas con Au NR después de la irradiación láser modulada con frecuencias variables y longitudes de pulso 13. Despolarización de la membrana celular también se registró después de NIR láser de iluminación de Au NR en cultivos primarios de neuronas del ganglio espiral 14. La primera aplicación in vivo con irradiado Au NR se ha demostrado recientemente. Eom y compañeros de trabajo expuestos Au rupias en su pico plasmónica y registraron un aumento de seis veces en la amplitud de los potenciales de acción del nervio compuesto (CNaPS) y una disminución de tres veces en el umbral de estimulación en ratas nervios ciáticos. Los cuartosrespuesta hanced se atribuyó a los efectos de calentamiento locales que resultan de la excitación del pico plasmónica NR 15. En el presente trabajo, se especifican los protocolos para la investigación de los efectos de la estimulación con láser en NG108-15 células neuronales cultivadas con Au rupias. Estos métodos proporcionan una simple, pero potente, forma de irradiar poblaciones celulares in vitro utilizando técnicas y materiales biológicos estándar. El protocolo se basa en un diodo láser de fibra acoplada (LD) que permite un funcionamiento seguro y la alineación repetible. La preparación de la muestra y los métodos de irradiación láser Au NR se pueden ampliar a diferentes formas de partículas y cultivos de células neuronales, siempre que los protocolos de síntesis y cultura específicas son conocidas, respectivamente.

<table><tbody><tr><td>Au NR</td><td>Sigma Aldrich</td><td>716812</td><td></td></tr><tr><td>NG108-15</td><td>Sigma Aldrich</td><td>8811230</td><td></td></tr><tr><td>DMEM</td><td>Sigma Aldrich</td><td>D6546</td><td></td></tr><tr><td>FCS</td><td>Life Technologies</td><td>10100147</td><td></td></tr><tr><td>L-glutamine</td><td>Sigma Aldrich</td><td>G7513</td><td></td></tr><tr><td>Penicillin/streptomycin</td><td>Life Technologies</td><td>15140122</td><td></td></tr><tr><td>Amphotericin B</td><td>Life Technologies</td><td>15290018</td><td></td></tr><tr><td>Formaldehyde</td><td>Sigma Aldrich</td><td>F8775</td><td></td></tr><tr><td>Triton X-100</td><td>BDH</td><td>T8532</td><td></td></tr><tr><td>BSA</td><td>Sigma Aldrich</td><td>A2058</td><td></td></tr><tr><td>Anti-&amp;beta;III-tubulin</td><td>Promega</td><td>G7121</td><td></td></tr><tr><td>TRITC-conjugated anti-mouse IgG antibody</td><td>Sigma Aldrich</td><td>T5393</td><td></td></tr><tr><td>DAPI</td><td>Invitrogen</td><td>D1306</td><td></td></tr><tr><td>Fluo-4 AM</td><td>Invitrogen</td><td>F14201</td><td></td></tr><tr><td>DMSO</td><td>Sigma Aldrich</td><td>472301</td><td></td></tr><tr><td>Pluronic F-127</td><td>Invitrogen</td><td>P6867</td><td></td></tr><tr><td>UV-Vis spectrometer</td><td>Varian Medical Systems Inc.</td><td>Cary 50 Bio</td><td></td></tr><tr><td>Mini centrifuge</td><td>Eppendorf</td><td>Mini Spin</td><td></td></tr><tr><td>Sonic bath</td><td>Unisonics Australia</td><td>FPX 10D</td><td></td></tr><tr><td>Cell culture incubator</td><td>Kendro</td><td>Hera Cell 150</td><td></td></tr><tr><td>Cell culture centrifuge</td><td>Hettich</td><td>Rotofix 32A</td><td></td></tr><tr><td>Laser diode</td><td>Optotech</td><td>780 nm single mode fibre - coupled LD</td><td></td></tr><tr><td>Optical fiber</td><td>Thorlabs</td><td>780 HP</td><td></td></tr><tr><td>Power meter</td><td>Coherent</td><td>Laser Check</td><td></td></tr><tr><td>ImageJ</td><td>http://rsb.info.nih.gov/ij/index.html</td><td></td><td></td></tr><tr><td>Epifluorescent microscope</td><td>Axon Instruments</td><td>ImageX-press 5000A</td><td></td></tr><tr><td>&amp;mu;-slide well</td><td>Ibidi</td><td>80826</td><td></td></tr><tr><td>Inverted confocal microscope</td><td>Carl Zeiss Microscopy Ltd.</td><td>LSM 510 meta-confocal microscope</td><td></td></tr><tr><td>Oscilloscope</td><td>Tektronix</td><td>TDS210</td><td></td></tr></tbody></table>

gold nanorod-assisted optical stimulation of neuronal cells

Recent studies have demonstrated that nerves can be stimulated in a variety of ways by the transient heating associated with the absorption of infrared light by water in neuronal tissue. This technique holds great potential for replacing or complementing standard stimulation techniques, due to the potential for increased localization of the stimulus and minimization of mechanical contact with the tissue. However, optical approaches are limited by the inability of visible light to penetrate deep into tissues. Moreover, thermal modelling suggests that cumulative heating effects might be potentially hazardous when multiple stimulus sites or high laser repetition rates are used. The protocol outlined below describes an enhanced approach to the infrared stimulation of neuronal cells. The underlying mechanism is based on the transient heating associated with the optical absorption of gold nanorods, which can cause triggering of neuronal cell differentiation and increased levels of intracellular calcium activity. These results demonstrate that nanoparticle absorbers can enhance and/or replace the process of infrared neural stimulation based on water absorption, with potential for future applications in neural prostheses and cell therapies.

Mediante el uso de los Protocolos 1, 2 y 3 descritos aquí, se observó un efecto estimulador en la diferenciación en células NG108-15 neuronales cultivadas con Au NP (Au rupias, poli (estirenosulfonato) presenta el revestimiento Au rupias y revestido con sílice Au NR) después de láser exposiciones entre 1,25 y 7,5 W · cm de -2. Las imágenes confocales de marcado con rhodamineB Au NR demostraron que las partículas se interiorizaron de 1 día de incubación 12. La localización se observó p...

Watch this Scientific Journal Video about Gold Nanorod-assisted Optical Stimulation of Neuronal Cells at JoVE.com

Gold Nanorod-assisted Optical Stimulation of Neuronal Cells

This protocol outlines how to use the transient heating associated with the optical absorption of gold nanorods to stimulate differentiation and intracellular calcium activity in neuronal cells. These results potentially open up new applications in neural prostheses and fundamental studies in neuroscience.

Oro nanorod asistida estimulación óptica de las células neuronales

Recent studies have demonstrated that nerves can be stimulated in a variety of ways by the transient heating associated with the absorption of infrared ...

gold-nanorod-assisted-optical-stimulation-of-neuronal-cells

Research

JoVE Journal

Neuroscience

8.9K vistas.  Swinburne University of Technology. This protocol outlines how to use the transient heating associated with the optical absorption of gold nanorods to stimulate differentiation and intracellular calcium activity in neuronal cells. These results potentially open up new applications in neural prostheses and fundamental studies in neuroscience.

Video: Gold Nanorod-assisted Optical Stimulation of Neuronal Cells

Using Affordable LED Arrays for Photo-Stimulation of Neurons

Standard slice electrophysiology has allowed researchers to probe individual components of neural circuitry by recording electrical responses of single cells in response to electrical or pharmacological manipulations1,2. With the invention of methods to optically control genetically targeted neurons (optogenetics), researchers now have an unprecedented level of control over specific groups of neurons in the standard slice preparation. In particular, photosensitive channelrhodopsin-2 (ChR2) allows researchers to activate neurons with light3,4. By combining careful calibration of LED-based photostimulation of ChR2 with standard slice electrophysiology, we are able to probe with greater detail the role of adult-born interneurons in the olfactory bulb, the first central relay of the olfactory system. Using viral expression of ChR2-YFP specifically in adult-born neurons, we can selectively control young adult-born neurons in a milieu of older and mature neurons. Our optical control uses a simple and inexpensive LED system, and we show how this system can be calibrated to understand how much light is needed to evoke spiking activity in single neurons. Hence, brief flashes of blue light can remotely control the firing pattern of ChR2-transduced newborn cells.

Adult-born neurons expressing ChR2 can be manipulated in slice electrophysiological preparations in order to examine their contribution towards the function of olfactory neural circuits.

Utilizando asequible Estructuras de LED para fotos-estimulación de las neuronas

Standard slice electrophysiology has allowed researchers to probe individual components of neural circuitry by recording electrical responses of single ...

Investigación

Neurociencias

Selective Viral Transduction of Adult-born Olfactory Neurons for Chronic in vivo Optogenetic Stimulation

Local interneurons are continuously regenerated in the olfactory bulb of adult rodents1-3. In this process, called adult neurogenesis, neural stem cells in the walls of the lateral ventricle give rise to neuroblasts that migrate for several millimeters along the rostral migratory stream (RMS) to reach and incorporate into the olfactory bulb. To study the different steps and the impact of adult-born neuron integration into preexisting olfactory circuits, it is necessary to selectively label and manipulate the activity of this specific population of neurons. The recent development of optogenetic technologies offers the opportunity to use light to precisely activate this specific cohort of neurons without affecting surrounding neurons4,5. Here, we present a series of procedures to virally express Channelrhodopsin2(ChR2)-YFP in a temporally restricted cohort of neuroblasts in the RMS before they reach the olfactory bulb and become adult-born neurons. In addition, we show how to implant and calibrate a miniature LED for chronic in vivo stimulation of ChR2-expressing neurons.

Selective Viral Transduction of Adult-born Olfactory Neurons for Chronic in vivo Optogenetic Stimulation

Adult-born neurons of the olfactory bulb can be optogenetically controlled using Channelrhodopsin2-expressing lentiviral injection in the rostral migratory stream and chronic photostimulation with an implanted miniature LED.

Transducción viral selectiva de adultos nacidos en las neuronas olfativas de las enfermedades crónicas En vivo Estimulación Optogenetic

Local interneurons are continuously regenerated in the olfactory bulb of adult rodents1-3. In this process, called adult neurogenesis, neural stem cells ...

Fiber-optic Implantation for Chronic Optogenetic Stimulation of Brain Tissue

Elucidating patterns of neuronal connectivity has been a challenge for both clinical and basic neuroscience. Electrophysiology has been the gold standard for analyzing patterns of synaptic connectivity, but paired electrophysiological recordings can be both cumbersome and experimentally limiting. The development of optogenetics has introduced an elegant method to stimulate neurons and circuits, both in vitro1 and in vivo2,3. By exploiting cell-type specific promoter activity to drive opsin expression in discrete neuronal populations, one can precisely stimulate genetically defined neuronal subtypes in distinct circuits4-6. Well described methods to stimulate neurons, including electrical stimulation and/or pharmacological manipulations, are often cell-type indiscriminate, invasive, and can damage surrounding tissues. These limitations could alter normal synaptic function and/or circuit behavior. In addition, due to the nature of the manipulation, the current methods are often acute and terminal. Optogenetics affords the ability to stimulate neurons in a relatively innocuous manner, and in genetically targeted neurons. The majority of studies involving in vivo optogenetics currently use a optical fiber guided through an implanted cannula6,7; however, limitations of this method include damaged brain tissue with repeated insertion of an optical fiber, and potential breakage of the fiber inside the cannula. Given the burgeoning field of optogenetics, a more reliable method of chronic stimulation is necessary to facilitate long-term studies with minimal collateral tissue damage. Here we provide our modified protocol as a video article to complement the method effectively and elegantly described in Sparta et al.8 for the fabrication of a fiber optic implant and its permanent fixation onto the cranium of anesthetized mice, as well as the assembly of the fiber optic coupler connecting the implant to a light source. The implant, connected with optical fibers to a solid-state laser, allows for an efficient method to chronically photostimulate functional neuronal circuitry with less tissue damage9 using small, detachable, tethers. Permanent fixation of the fiber optic implants provides consistent, long-term in vivo optogenetic studies of neuronal circuits in awake, behaving mice10 with minimal tissue damage.

The development of optogenetics now provides the means to precisely stimulate genetically defined neurons and circuits, both in vitro and in vivo. Here we describe the assembly and implantation of a fiber optic for chronic photostimulation of brain tissue.

La implantación de fibra óptica para la estimulación optogenético crónica en el tejido cerebral

Elucidating patterns of neuronal connectivity has been a challenge for both clinical and basic neuroscience. Electrophysiology has been the gold standard ...

Gold Nanoparticle Modified Carbon Fiber Microelectrodes for Enhanced Neurochemical Detection

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into glass capillaries, pulled to a fine taper, and then sealed using an epoxy to create electrode materials that are used for fast scan cyclic voltammetry testing. The use of bare CFMEs has several limitations, though. First and foremost, the carbon fiber contains mostly basal plane carbon, which has a relatively low surface area and yields lower sensitivities than other nanomaterials. Furthermore, the graphitic carbon is limited by its temporal resolution, and its relatively low conductivity. Lastly, neurochemicals and macromolecules have been known to foul at the surface of carbon electrodes where they form non-conductive polymers that block further neurotransmitter adsorption. For this study, we modify CFMEs with gold nanoparticles to enhance neurochemical testing with fast scan cyclic voltammetry. Au3+ was electrodeposited or dipcoated from a colloidal solution onto the surface of CFMEs. Since gold is a stable and relatively inert metal, it is an ideal electrode material for analytical measurements of neurochemicals. Gold nanoparticle modified (AuNP-CFMEs) had a stability to dopamine response for over 4 h. Moreover, AuNP-CFMEs exhibit an increased sensitivity (higher peak oxidative current of the cyclic voltammograms) and faster electron transfer kinetics (lower &#916;EP or peak separation) than bare unmodified CFMEs. The development of AuNP-CFMEs provides the creation of novel electrochemical sensors for detecting fast changes in dopamine concentration and other neurochemicals at lower limits of detection. This work has vast applications for the enhancement of neurochemical measurements. The generation of gold nanoparticle modified CFMEs will be vitally important for the development of novel electrode sensors to detect neurotransmitters in vivo in rodent and other models to study neurochemical effects of drug abuse, depression, stroke, ischemia, and other behavioral and disease states.

In this study, we modify carbon-fiber microelectrodes with gold nanoparticles to enhance the sensitivity of neurotransmitter detection.

Microelectrodos de fibra de carbono modificados por nanopartículas de oro para una detección neuroquímica mejorada

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into ...

Química

Preparation and Photoacoustic Analysis of Cellular Vehicles Containing Gold Nanorods

Gold nanorods are attractive for a range of biomedical applications, such as the photothermal ablation and the photoacoustic imaging of cancer, thanks to their intense optical absorbance in the near-infrared window, low cytotoxicity and potential to home into tumors. However, their delivery to tumors still remains an issue. An innovative approach consists of the exploitation of the tropism of tumor-associated macrophages that may be loaded with gold nanorods in vitro. Here, we describe the preparation and the photoacoustic inspection of cellular vehicles containing gold nanorods. PEGylated gold nanorods are modified with quaternary ammonium compounds, in order to achieve a cationic profile. On contact with murine macrophages in ordinary Petri dishes, these particles are found to undergo massive uptake into endocytic vesicles. Then these cells are embedded in biopolymeric hydrogels, which are used to verify that the stability of photoacoustic conversion of the particles is retained in their inclusion into cellular vehicles. We are confident that these results may provide new inspiration for the development of novel strategies to deliver plasmonic particles to tumors.

We show the preparation and address the feasibility of cellular vehicles containing gold nanorods for the photoacoustic imaging of cancer.

Análisis preparación y fotoacústica de Vehículos celulares que contienen oro Nanorods

Gold nanorods are attractive for a range of biomedical applications, such as the photothermal ablation and the photoacoustic imaging of cancer, thanks to ...

Bioingeniería

Optical Control of Living Cells Electrical Activity by Conjugated Polymers

Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity.
In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported protocol is of general validity and can be straightforwardly extended to other biological preparations.

A method for stimulation of in-vitro cell cultures electrical activity with visible light, based on the use of organic semiconducting polymers is described.

Control óptico de células vivas Actividad Eléctrica por conjugadas Polímeros

Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated ...

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing.

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

Optogenetics has become a powerful tool for use in behavioral neuroscience experiments. This protocol offers a step-by-step guide to the design and set-up of laser systems, and provides a full protocol for carrying out multiple and simultaneous in vivo optogenetic stimulations compatible with most rodent behavioral testing paradigms.

In vivo optogenético la estimulación del sistema nervioso central de roedores

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution ...

Optogenetic Stimulation of the Auditory Nerve

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted deaf subjects1-6. Nonetheless, sound coding with current CIs has poor frequency and intensity resolution due to broad current spread from each electrode contact activating a large number of SGNs along the tonotopic axis of the cochlea7-9. Optical stimulation is proposed as an alternative to electrical stimulation that promises spatially more confined activation of SGNs and, hence, higher frequency resolution of coding. In recent years, direct infrared illumination of&#160;the cochlea has been used to evoke responses in the auditory nerve10. Nevertheless it requires higher energies than electrical stimulation10,11 and uncertainty remains as to the underlying mechanism12. Here we describe a method based on optogenetics to stimulate SGNs with low intensity blue light, using transgenic mice with neuronal expression of channelrhodopsin 2 (ChR2)13 or virus-mediated expression of the ChR2-variant CatCh14. We used micro-light emitting diodes (&#181;LEDs) and fiber-coupled lasers to stimulate ChR2-expressing SGNs through a small artificial opening (cochleostomy) or the round window. We assayed the responses by scalp recordings of light-evoked potentials (optogenetic auditory brainstem response: oABR) or by microelectrode recordings from the auditory pathway and compared them with acoustic and electrical stimulation.

Cochlear implants (CIs) enable hearing by direct electrical stimulation of the auditory nerve. However, poor frequency and intensity resolution limits the quality of hearing with CIs. Here we describe optogenetic stimulation of the auditory nerve in mice as an alternative strategy for auditory research and developing future CIs.

Estimulación Optogenética del nervio auditivo

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted ...

Silicon Nanowires and Optical Stimulation for Investigations of Intra- and Intercellular Electrical Coupling

Myofibroblasts can spontaneously internalize silicon nanowires (SiNWs), making them an attractive target for bioelectronic applications. These cell-silicon hybrids offer leadless optical modulation capabilities with minimal perturbation to normal cell behavior. The optical capabilities are obtained by the photothermal and photoelectric properties of SiNWs. These hybrids can be harvested using standard tissue culture techniques and then applied to different biological scenarios. We demonstrate here how these hybrids can be used to study the electrical coupling of cardiac cells and compare how myofibroblasts couple to one another or to cardiomyocytes. This process can be accomplished without special equipment beyond a fluorescent microscope with coupled laser line. Also shown is the use of a custom-built MATLAB routine that allows the quantification of calcium propagation within and between the different cells in the culture. Myofibroblasts are shown to have a slower electrical response than that of cardiomyocytes. Moreover, the myofibroblast intercellular propagation shows slightly slower, though comparable velocities to their intracellular velocities, suggesting passive propagation through gap junctions or nanotubes. This technique is highly adaptable and can be easily applied to other cellular arenas, for in vitro as well as in vivo or ex vivo investigations.

This protocol describes the use of silicon nanowires for intracellular optical bio-modulation of cell in a simple and easy to perform method. The technique is highly adaptable to diverse cell types and can be used for in vitro as well as in vivo applications.

Nanohilos de silicio y estimulación óptica para investigaciones de acoplamiento eléctrico intra e intercelular

Myofibroblasts can spontaneously internalize silicon nanowires (SiNWs), making them an attractive target for bioelectronic applications. These ...

Optrode Array for Simultaneous Optogenetic Modulation and Electrical Neural Recording

During the last decade, optogenetics has become an essential tool for the investigation of neural signaling due to its unique capability of selective neural modulation or monitoring. As specific types of neuronal cells can be genetically modified to express opsin proteins, optogenetics enables optical stimulation or inhibition of the selected neurons. There have been several technological advances in the optical system for optogenetics. Recently, it was proposed to combine the optical waveguide for light delivery with electrophysiological recording to simultaneously monitor the neural responses to optogenetic stimulation or inhibition. In this study, an implantable optrode array (2x2 optical fibers) was developed with embedded multichannel electrodes. 
A light-emitting diode (LED) was employed as a light source, and a microfabricated microlens array was integrated to provide sufficient light power at the tip of the optical fibers. The optrode array system comprises the disposable part and the reusable part. The disposable part has optical fibers and electrodes, while the reusable part has the LED and electronic circuitry for light control and neural signal processing. The novel design of the implantable optrode array system is introduced in the accompanying video in addition to the procedure of the optrode implantation surgery, optogenetic light stimulation, and the electrophysiological neural recording. The results of in vivo experiments successfully showed time-locked neural spikes evoked by the light stimuli from hippocampal excitatory neurons of mice.

Here, we present the fabrication method of an optrode system with optical fibers for light delivery and an electrode array for neural recording. In vivo experiments with transgenic mice expressing channelrhodopsin-2 show the feasibility of the system for simultaneous optogenetic stimulation and electrophysiological recording.

Optrode Array para modulación optogenética simultánea y grabación neuronal eléctrica

During the last decade, optogenetics has become an essential tool for the investigation of neural signaling due to its unique capability of selective ...