Name: trapping of micro particles in nanoplasmonic optical lattice
Uploaded: 2017-09-05T12:30:00.000+00:00
Duration: 7 min 20 s
Description: Watch this Scientific Journal Video about Trapping of Micro Particles in Nanoplasmonic Optical Lattice at JoVE.com

Y. T. Y. gostaria de reconhecer o apoio do Ministério da ciência e tecnologia sob concessão números mais 105-2221-E-007-MY3 e da National Tsing Hua University sob concessão números 105N518CE1 e 106N518CE1 financeiro.

1. Setup óptico Nota: O princípio da instalação do óptico é ilustrado na Figura 1.
Pinça <ol><li>conjunto até o óptico kit (veja a Tabela de materiais) e o módulo de fluorescência (ver Tabela de materiais) como por seus manuais. Conectar uma fonte de 470 nm azul luz emitindo luz de diodo (LED) para o módulo fluorescente.</li>
	<li>Substituir a alta abertura numérica (NA) (at = 1.25, ampliação 100x) objectivo de imersão de óleo por um trabalho de longo distância objetivo do microscópio (WD) (comprimento focal 3,6 mm, WD = 10,6 mm, at = 0,5).</li>
	<li>Remover a lente na seção expansão de feixe do kit montado para alcançar solto com foco de raio laser.</li>
	<li>Vez na fonte de alimentação e a corrente para o laser de diodo de nm de comprimento de onda 980 e uso o carregado acoplado a câmera do dispositivo (CCD) para certificar-se de que o feixe de laser é alinhado corretamente. 
	Nota: Se o feixe de laser é bem alinhado, a câmera CCD lerá um ponto Gaussian.</li>
</ol> 2. Nanofabricação fabricação de marcador de <ol><li>. 
	Nota: Marcadores irão ajudar a posicionar a matriz de nanoplasmonic durante o processo de fabricação e o experimento de armadilhagem subsequentes. O processo detalhado é ilustrado na Figura complementar 1.
	<ol><li>Filme de óxido de estanho (ITO) de índio depósito 40 nm em uma lamela de espessura 0,17 mm com pulverização catódica. 
		Nota: O filme ITO ajudará a descarga de elétrons durante o processo de litografia e-feixe subsequentes.</li>
		<li>Spin revestir uma camada de 8 µm de fotorresiste positivo com rotação velocidade 4000 rpm e tempo de 30 s, com um aplicador de rotação.</li>
		<li>Soft cozer a amostra a 90 ° C por 5 min e alinhar a amostra com a Fotomáscara para marcador e expor a amostra à luz para 80 UV s no alinhador de máscara.</li>
		<li>Embeber a amostra no desenvolvedor fotorresiste por 130 s.</li>
		<li>Depositar uma camada de 2 nm de crómio e uma camada de 40 nm de ouro para a amostra usando evaporação térmica. 18</li> <li>mergulhar a amostra em acetona e colocá-lo em um líquido de limpeza ultra-sônico que operam em 43 kHz e 150 W por 5 min para fora do elevador</li>
	</ol></li> <li>Fabricação de matriz Nanoplasmonic <ol><li>casaco Spin uma camada de e-feixe resistir PMMA 120K com centrifugação 5000 rpm por 30 s em um aplicador de rotação. Asse a amostra a 160 ° C por 3 min em uma chapa quente.</li>
		<li>Spin revestir outra camada de resistir e-feixe PMMA 960K com centrifugação 5000 rpm por 30 s em um aplicador de rotação. Asse a amostra a 160 ° C por 3 min em uma chapa quente.</li>
		<li>Escritor e-feixe de uso para expor o feixe e resistir com aceleração tensão 30 kV e dosagem 400 C/cm 2.</li>
		<li>Depositar uma camada de 40 nm de ouro em um evaporador térmico.</li>
		<li>Mergulhar a amostra em acetona e colocá-lo em um líquido de limpeza ultra-sônico por 5 min para fora do elevador</li>
	</ol></li></ol> 3. Exemplo de sistema de resfriamento e a calibração de temperatura Nota: A amostra refrigerar cenografia é mostrada na complementar Figura 2.
<ol><li>Fazendo o circuito controlador para refrigeração de amostra <ol><li>Coloque os resistores, transistores de junção bipolar e transistores de efeito de campo de óxido de metal de poder na placa de circuito personalizada seguindo o diagrama de circuito da complementar Figura 3 . Todos esses componentes com ferro de solda de solda.</li>
		<li>Fios de conexão entre a porta de controle da placa de circuito e a placa de controle eletrônico. Ligue os fios entre a porta de saída da placa de circuito e resfriamento termoelétrico (TEC) elemento. Coloque o elemento TEC no palco a amostra com o calor a afundar-se. 
		&#8203; Nota: TEC o elemento tem um buraco no centro para permitir que o feixe de laser passar.</li>
		<li>Fios de conexão da placa de circuito para 5 V de alimentação. Use a câmera infravermelha prospectiva para monitorar a temperatura para verificar se o resfriamento termoelétrico é corretamente refrigerar para baixo.</li>
	</ol></li> <li>Calibração da temperatura medida na prospectivas câmera e resistência temperatura detector (IDT) termômetro infravermelho.
	<ol><li>Coloque o Termómetro RTD em uma lamela em branco e aplique uma pequena quantidade de pasta térmica para assegurar o adequado contato térmico entre o Termómetro RTD e lamela.</li>
		<li>Alterar o ajuste da potência de saída do circuito de controle eletrônico para elemento TEC, alterando o ciclo de trabalho de configuração de modulação de largura de pulso e esperar por 3 min certificar-se de que atingir a temperatura de estado estacionário. Leia a temperatura com o termômetro de IDT.</li>
		<li>Vez na câmera infravermelha olhando para a frente e monitor da temperatura. Repita isto em várias configurações de potência de saída para obter a curva de calibração de temperatura. Uma curva de calibração de temperatura representativa é mostrada na Figura complementar 4. 
		Nota: É fundamental fazer calibração entre RTD termômetro e a câmera de infravermelha olhando para a frente porque a leitura da temperatura da câmara de infravermelha voltada para o futuro deve ser exactos para garantir a temperatura correta é alcangada.</li>
	</ol></li></ol> 4. Interceptação de micropartículas de <ol><li>dilua micro partículas de poliestireno do diâmetro 2 µm em água deionizada em um microcentrifugetube de relação volume apropriado. 
	Nota: A concentração de micro partículas pode ser ajustada de acordo com o objetivo do experimento. Enquanto menor concentração permite um intervalo de tempo de amostra entre eventos de armadilhagem única partícula, maior concentração encurtará o tempo para a captura de partículas múltiplas. Para a captura de partícula única, uma concentração típica é ~0.05% (w/v).</li>
	<li>Colocar a amostra com a matriz nanoplasmonic no palco e ligar um 470 nm LED como fonte de luz de fluorescência e definir manualmente a potência de 5 mW para a imagem latente de campo brilhante.</li>
	<li>Use o marcador para localizar a matriz nanoplasmonic, alinhe a amostra e usar a câmera do CCD para certificar-se de que a matriz está no centro da região de interesse na tela do computador.</li>
	<li>Dispense 10 µ l das diluídos micro partículas de diâmetro 2 µm na amostra com uma pipeta micro.</li>
	<li>Ligar a alimentação em corrente para o diodo de nm de comprimento de onda 980 para excitar a ressonância plasmônico da matriz com um poder no intervalo ~ 1 mW a 10 mW.</li>
	<li>Manualmente, ligue a fonte de alimentação para a placa de controle eletrônico para resfriar a amostra para um estado constante de temperatura ~ 4 ° C.</li>
	<li>No software visualizador, clique o &#34; gravar vídeo &#34; sequência para abrir a caixa de diálogo de gravação. Clique o &#34; registro &#34; botão para iniciar o vídeo 1.5 do movimento das partículas de micro, com uma taxa de quadros de 10 quadros/s de gravação da amostra sob a influência do feixe de laser, usando a câmera do CCD. Clique o &#34; parar de &#34; o botão para parar a gravação. Veja o vídeo 1.</li>
</ol>

<ol>
	<li>Ashkin, A., Dziedzic, J. M., Bjorkholm, J. E., Chu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Observation+of+a+single-beam+gradient+force+optical+trap+for+dielectric+particles.">Observation of a single-beam gradient force optical trap for dielectric particles.</a> Opt.Lett. 11, 288-290 (1986).</li><li>Grier, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+revolution+in+optical+manipulation.">A revolution in optical manipulation.</a> Nature. 424, 21-27 (2003).</li><li>Wright, W. H., Sonek, G. J., Berns, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiation+on+trapping+forces+with+optical+tweezers.">Radiation on trapping forces with optical tweezers.</a> Appl. Phys. Lett. 63, 715-717 (1993).</li><li>Kawata, S., Tani, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optically+driven+Mie+particles+in+an+evanescent+field+along+a+channel+waveguide.">Optically driven Mie particles in an evanescent field along a channel waveguide.</a> Opt. Lett. 21, 1768-1770 (1996).</li><li>Yang, A. H. J., Moore, S. D., Schmit, B. S., Klug, M., Lipson, M., Erickson, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Manipulation+of+nanoparticles+and+biomolecules+in+sub-wavelength+slot+waveguides.">Optical Manipulation of nanoparticles and biomolecules in sub-wavelength slot waveguides.</a> Nature. 457, 71-75 (2009).</li><li>Lin, S., Schonbrun, E., Crozier, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+manipulation+with+planar+silicon+microring+resonators.">Optical manipulation with planar silicon microring resonators.</a> Nano Lett. 10, 2408-2411 (2010).</li><li>Mandal, S., Serey, X., Erickson, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanomanipulation+using+silicon+photonic+crystal+resonators.">Nanomanipulation using silicon photonic crystal resonators.</a> Nano Lett. 2010 (10), 99-104 (2010).</li><li>Lin, S., Crozier, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Planar+silicon+microrings+as+wavelength-+multiplexed+optical+traps+for+storing+and+sensing+particles.">Planar silicon microrings as wavelength- multiplexed optical traps for storing and sensing particles.</a> Lab Chip. 11, 4047-4051 (2011).</li><li>Juan, M. L., Righini, M., Quidant, M., R, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmonic+nano+optical+tweezers.">Plasmonic nano optical tweezers.</a> Nat. Photon. 5, 349-356 (2011).</li><li>Huang, J. S., Yang, Y. -. 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+origin+and+future+of+plasmonic+optical+tweezer.">The origin and future of plasmonic optical tweezer.</a> Nanomaterials. 5, 1048-1065 (2015).</li><li>Pang, Y., Gordon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+trapping+of+single+protein.">Optical trapping of single protein.</a> Nano Lett. 12, 402-406 (2012).</li><li>Chen, K. Y., Lee, A. T., Hung, C. C., Huang, J. S., Yang, Y. -. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport+and+trapping+in+two-dimensional+nanoscale+plasmonic+optical+lattice.">Transport and trapping in two-dimensional nanoscale plasmonic optical lattice.</a> Nano Lett. 13, 4118-4122 (2013).</li><li>Cuche, A., Stein, B., Canguier-Durand, A., Devaux, E., Genet, C., Ebbesen, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brownian+motion+in+a+designer+force+field:+Dynamical+effects+of+negative+refraction+on+nanoparticles.">Brownian motion in a designer force field: Dynamical effects of negative refraction on nanoparticles.</a> Nano Lett. 12, 4329-4332 (2012).</li><li>Baffou, G., Berto, P., Urena, E. B., Quidant, R., Monnert, S. J., Polleux, J., Righeault, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoinduced+heating+of+nanoparticle+arrays.">Photoinduced heating of nanoparticle arrays.</a> ACS Nano. 8, 6478-6488 (2013).</li><li>Roxworthy, B. J., Bhuiya, A. M., Vanka, S. P., Toussant, K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+and+controlling+plasmon-induced+convection.">Understanding and controlling plasmon-induced convection.</a> Nat. Commun. 5, (2014).</li><li>Yang, T. P., Yossifon, G., Yang, Y. -. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+near-field+and+convectional+transport+behavior+of+micro+and+nano+particles+in+nanoscale+plasmonic+optical+lattice.">Characterization of the near-field and convectional transport behavior of micro and nano particles in nanoscale plasmonic optical lattice.</a> Biomicrofluidics. 10, 034102 (2016).</li><li>Chen, Y. -. C., Yossifon, G., Yang, Y. -. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Supression+of+phtothermal+convection+of+micro+particles+in+two+dimensional+nanoplamonic+optical+lattice.">Supression of phtothermal convection of micro particles in two dimensional nanoplamonic optical lattice.</a> Appl. Phys. Lett. 109, 201111 (2016).</li><li>Smith, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Thin film deposition: principles and practice. , (1995).</li><li>Zehtabi-Oskuie, A., Bergeron, J. G., Gordon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow-dependent+double-nanohole+optical+trapping+of+20+nm+polystyrene+nanospheres.">Flow-dependent double-nanohole optical trapping of 20 nm polystyrene nanospheres.</a> Sci. Rep. 2, 966 (2012).</li><li>Zhang, W., Huang, L., Santschi, C., Martin, O. J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trapping+and+sensing+10+nm+metal+nanoparticles+using+plasmonic+dipole+antennas.">Trapping and sensing 10 nm metal nanoparticles using plasmonic dipole antennas.</a> Nano Lett. 10, 1006-1011 (2010).</li><li>Pang, Y., Gordon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+trapping+of+12+nm+dielectric+spheres+using+double-nanoholes+in+a+gold+film.">Optical trapping of 12 nm dielectric spheres using double-nanoholes in a gold film.</a> Nano Lett. 2011 (11), 3763-3767 (2011).</li></ol>

Os autores não têm nada para divulgar.

O procedimento descrito aqui permite que o leitor reproduzir confiantemente armadilhas em uma base diária. Uma orientação empírica geral para projetar um lattice ótico utilizável é usar um tamanho comparável para plasmônico nanoarray, distância interdisc e preso o tamanho de partícula. Comparado a um nanostructure plasmônico único, isolado, o projeto de estrutura óptica em conjunto com a alta potência óptica proporcionada pelo resfriamento da amostra a ~ 4 ° C, usado aqui grandemente aumenta a probabilid...

A captura óptica de partículas micro escala foi originalmente desenvolvida por Arthur Askin na década de 1970. Desde a sua invenção, a técnica foi desenvolvida como uma ferramenta versátil para micro e nanomanipulação1,2. Convencional óptico prendendo com base no campo distante focar princípio inerentemente é limitada pela difração em seu confinamento espacial, onde a força de armadilhagem diminui drasticamente (seguir um ~umalei de3 de uma partícula de raio um) 3. para superar tais limites de difração, pesquisadores desenvolveram técnicas de armadilhagem óptica de campo próximo, com base no campo evanescente óptico usando nanoestruturas metálicas plasmônico e, além disso, a captura de nanoescala objetos para baixo para moléculas de proteína única tem sido demonstrada4,5,6,7,8,9,10,11. Além disso, o retículo óptico plasmônico é criado a partir de matrizes de nanoestruturas plasmônico periódicas para conferir o transporte de longo alcance do micro e nanopartículas e múltiplas partículas empilhamento11,12. Um grande obstáculo para interromper a captura em um lattice ótico é convecção fototérmicos e foram envidados esforços para elucidar seus efeitos por vários grupos14,15,16,17. Usando a função de Green, Baffou et al ter calculado um perfil de temperatura por cada nanostructure plasmônico como um aquecedor de ponto de modelagem e então experimentalmente validados seu modelo14. Grupo do Toussant também mediu a convecção induzida por plasmon com partícula velocimetry15. Grupo do autor também tem caracterizado o transporte campo próximo e convecçao e demonstrou uma estratégia de engenharia para suprimir originando convecção16,17.
Aqui apresentamos o projeto de uma instalação de ótica e um procedimento detalhado especificamente para experimentos de armadilhagem plasmônico retículo óptico. O potencial óptico foi criado por iluminando uma matriz de ouro nanodiscs com um feixe gaussiano vagamente concentrado. Um esquema para suprimir a convecção originando pelo resfriamento da amostra a uma temperatura baixa (~ 4 ° C) para a captura ideal é também descrever aqui17. Sob a aproximação de Boussinesq, uma ordem de magnitude estimada da convecção natural velocidade u é dada por u ~L2 gβΔT / v, onde L é a escala de comprimento da fonte de calor e Δ T é o aumento de temperatura em relação a referência devido ao aquecimento.  g e β são a aceleração gravitacional e coeficiente de expansão térmica, respectivamente. Em temperaturas perto de 4 ° C, a densidade do meio de água apresenta dependência de temperatura anômalas e isso se traduz em um coeficiente de expansão térmica próximo de zero e, portanto, uma convecção originando muito pequeno.

<table><tbody><tr><td>Thermoelectric cooling element</td><td>Thorlabs</td><td>TEC 1.4-6</td><td>TEC element for sample cooling</td></tr><tr><td>RTD thermometer</td><td>Omega Engineering</td><td>RTD Thermometer 969C</td><td></td></tr><tr><td>Forward looking infrared camera</td><td>FLIR&amp;nbsp;</td><td>FLIR One</td><td>IR camera for temperature monitoring</td></tr><tr><td>light emitting diode light source</td><td>Touchbright</td><td></td><td>Light source for illumination for fluorescent imaging</td></tr><tr><td>Long working distance objective</td><td>Olympus</td><td>LMPLFLN</td><td>For illuminating the sample and imaging</td></tr><tr><td>Optical trap kit</td><td>Thorlabs</td><td>OTKB/M</td><td></td></tr><tr><td>Cover slip</td><td></td><td></td><td>thickness 0.17 mm</td></tr><tr><td>Scanning electron microscope</td><td>Hitachi</td><td>SEM-Hitachi S3400N</td><td></td></tr><tr><td>Electron beam blanker</td><td>DEBEN</td><td>PCD beam blanker</td><td>the blanker is added to the scanning electron microscope&amp;nbsp;</td></tr><tr><td>Thermal evaporator</td><td>SYSKEY Technology</td><td></td><td></td></tr><tr><td>Mask aligner</td><td>Karl Suss</td><td>MJB 3</td><td>For marker fabrication</td></tr><tr><td>Electron beam resist</td><td>Sigma Alrich</td><td>PMMA 120K</td><td>For e-beam lithography</td></tr><tr><td>Electron beam resist</td><td>Sigma Alrich</td><td>PMMA 960K</td><td>For e-beam lithography</td></tr><tr><td>Fluoresent labeled polystyrene microspheres</td><td>Polyscience</td><td></td><td>2 um diameter</td></tr><tr><td>Bipolar transistor</td><td>Mouser</td><td>2N3904</td><td>quantity 2 for TEC driver circuit</td></tr><tr><td>Bipolar transistor</td><td>Mouser</td><td>2N3906</td><td>quantity 2 for TEC driver circuit</td></tr><tr><td>MOSFET power transistor</td><td>Mouser</td><td>IRF5305</td><td>quantity 2 for TEC driver circuit</td></tr><tr><td>MOSFET power transistor</td><td>Mouser</td><td>IRF131ON</td><td>quantity 2 for TEC driver circuit</td></tr><tr><td>10 kOhm resistor</td><td>Mouser</td><td></td><td>quantity 6 for TEC driver circuit</td></tr><tr><td>910 Ohm resistor</td><td>Mouser</td><td></td><td>quantity 2 for TEC driver circuit</td></tr><tr><td>Photoresist</td><td>Microchemicals</td><td>AZ4620</td><td>For marker fabrication</td></tr><tr><td>Acetone</td><td>Sigma Alrich</td><td></td><td>For marker fabrication</td></tr><tr><td>Fluorescence Module for the OTKB/M, Metric Threads</td><td>Thorlabs</td><td>OTKB-FL/M</td><td></td></tr><tr><td>Fluorescent filter set</td><td>Thorlabs</td><td>MDF-FITC</td><td>For Fluorescein Isothiocyanate (FITC)</td></tr><tr><td>Ultrasonic cleaner</td><td>Delta</td><td>DC150H</td><td>For the lift off step</td></tr></tbody></table>

trapping of micro particles in nanoplasmonic optical lattice

A Pinça óptica plasmônico foi desenvolvida para superar os limites de difração da pinça óptica convencional de campo distante. Plasmônico óptica treliça consiste de uma matriz de nanoestruturas, que exibem uma variedade de armadilhas e comportamentos de transporte. Nós relatamos os procedimentos experimentais para capturar micropartículas em um lattice ótico nanoplasmonic quadrado simples. Também descrevemos a configuração óptica e a nanofabricação de uma matriz de nanoplasmonic. O potencial óptico é criado por iluminando uma matriz de nanodiscs de ouro com um feixe gaussiano de 980 nm comprimento de onda e ressonância de plasmon emocionante. O movimento das partículas é monitorado por imagens de fluorescência. Um esquema para suprimir originando convecção também é descrito para aumentar a potência óptica utilizável para interceptação de ideal. Supressão da convecção é alcançado pelo resfriamento da amostra a uma temperatura baixa e utilizando o coeficiente de expansão térmica próximo de zero de um meio de água. Tanto transporte de partícula única e múltiplas armadilhas de partícula são relatados aqui.

Trajetórias de partícula única foram gravadas por uma câmera CCD na nossa experiência e as imagens foram processadas com um programa personalizado para extrair trajetória16 do cada partícula. Resultados representativos são exibidos na Figura 3 e 1 vídeo para microesferas com diâmetros de 2 µm. foram observadas várias armadilhas de partícula dentro lattice ótico. Imagens sucessivas, extraídas de um vídeo...

Watch this Scientific Journal Video about Trapping of Micro Particles in Nanoplasmonic Optical Lattice at JoVE.com

Trapping of Micro Particles in Nanoplasmonic Optical Lattice

Descrevemos um procedimento para interceptar opticamente micropartículas em nanoplasmonic lattice ótico.

Captura de Micro partículas em Lattice ótico Nanoplasmonic

The plasmonic optical tweezer has been developed to overcome the diffraction limits of the conventional far field optical tweezer. Plasmonic optical ...

trapping-of-micro-particles-in-nanoplasmonic-optical-lattice

Research

JoVE Journal

Bioengineering

6.5K visualizações.  National Tsing Hua University. Descrevemos um procedimento para interceptar opticamente micropartículas em nanoplasmonic lattice ótico.

Vídeo: Trapping of Micro Particles in Nanoplasmonic Optical Lattice

Optical Trapping of Nanoparticles

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

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

Captura óptica de nanopartículas

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

Engenharia

Three-dimensional Optical-resolution Photoacoustic Microscopy

Optical microscopy, providing valuable insights at the cellular and organelle levels, has been widely recognized as an enabling biomedical technology. As the mainstays of in vivo three-dimensional (3-D) optical microscopy, single-/multi-photon fluorescence microscopy and optical coherence tomography (OCT) have demonstrated their extraordinary sensitivities to fluorescence and optical scattering contrasts, respectively. However, the optical absorption contrast of biological tissues, which encodes essential physiological/pathological information, has not yet been assessable. 
The emergence of biomedical photoacoustics has led to a new branch of optical microscopy optical-resolution photoacoustic microscopy (OR-PAM)1, where the optical irradiation is focused to the diffraction limit to achieve cellular1 or even subcellular2 level lateral resolution. As a valuable complement to existing optical microscopy technologies, OR-PAM brings in at least two novelties. First and most importantly, OR-PAM detects optical absorption contrasts with extraordinary sensitivity (i.e., 100%). Combining OR-PAM with fluorescence microscopy3 or with optical-scattering-based OCT4 (or with both) provides comprehensive optical properties of biological tissues. Second, OR-PAM encodes optical absorption into acoustic waves, in contrast to the pure optical processes in fluorescence microscopy and OCT, and provides background-free detection. The acoustic detection in OR-PAM mitigates the impacts of optical scattering on signal degradation and naturally eliminates possible interferences (i.e., crosstalks) between excitation and detection, which is a common problem in fluorescence microscopy due to the overlap between the excitation and fluorescence spectra. 
Unique for optical absorption imaging, OR-PAM has demonstrated broad biomedical applications since its invention, including, but not limited to, neurology5, 6, ophthalmology7, 8, vascular biology9, and dermatology10. In this video, we teach the system configuration and alignment of OR-PAM as well as the experimental procedures for in vivo functional microvascular imaging.

Optical-resolution photoacoustic microscopy (OR-PAM) is an emerging technology capable of imaging optical absorption contrasts in vivo with cellular resolution and sensitivity. Here, we provide a visualized instruction on the experimental protocols of OR-PAM, including system configuration, system alignment, typical in vivo experimental procedures, and functional imaging schemes.

Tridimensional Optical resolução Microscopia Fotoacústica

Optical microscopy, providing valuable insights at the cellular and organelle levels, has been widely recognized as an enabling biomedical technology. As ...

Bioengenharia

Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET's have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP's generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.

Plasmonic tweezers and photonic crystal nanostructures are shown to produce useful enhancements in the efficiency and orientation control of optically trapping micro- and nano-particles.

Utilização de Nanoestruturas Cristal plasmônicos e Fotônica para Manipulação de Micro-e Nanopartículas melhorada

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological ...

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

We demonstrate how optical tweezers may provide a sensitive tool to analyze the fluidic vibrations generated by the movement of small aquatic organisms. A single gold nanoparticle held by an optical tweezer is used as a sensor to quantify the rhythmic motion of a Nauplius larva (Artemia salina) in a water sample. This is achieved by monitoring the time dependent displacement of the trapped nanoparticle as a consequence of the Nauplius activity. A Fourier analysis of the nanoparticle&#39;s position then yields a frequency spectrum that is characteristic to the motion of the observed species. This experiment demonstrates the capability of this method to measure and characterize the activity of small aquatic larvae without the requirement to observe them directly and to gain information about the position of the larvae with respect to the trapped particle. Overall, this approach could give an insight on the vitality of certain species found in an aquatic ecosystem and could expand the range of conventional methods for analyzing water samples.

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

We use optical tracking of plasmonic nanoparticles to probe and characterize the frequency movements of aquatic organisms.

Analisando o movimento da Nauplius &#39;<em&gt; Artemia salina</em&gt; &#39;Por Optical Rastreamento de plasmônicos Nanopartículas

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

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

Fabricação e operação de uma Correia Transportadora Nano-óptica

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

Armadilha óptica carregamento de dielétrico micropartículas no ar

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

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

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

Plasmonic captura e liberação de nanopartículas em um ambiente de Monitoramento

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

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

The possibility to generate and measure rotation and torque at the nanoscale is of fundamental interest to the study and application of biological and artificial nanomotors and may provide new routes towards single cell analysis, studies of non-equilibrium thermodynamics, and mechanical actuation of nanoscale systems. A facile way to drive rotation is to use focused circularly polarized laser light in optical tweezers. Using this approach, metallic nanoparticles can be operated as highly efficient scattering-driven rotary motors spinning at unprecedented rotation frequencies in water.
In this protocol, we outline the construction and operation of circularly-polarized optical tweezers for nanoparticle rotation and describe the instrumentation needed for recording the Brownian dynamics and Rayleigh scattering of the trapped particle. The rotational motion and the scattering spectra provides independent information on the properties of the nanoparticle and its immediate environment. The experimental platform has proven useful as a nanoscopic gauge of viscosity and local temperature, for tracking morphological changes of nanorods and molecular coatings, and as a transducer and probe of photothermal and thermodynamic processes.

Plasmonic gold nanorods can be trapped in liquids and rotated at kHz frequencies using circularly-polarized optical tweezers. Introducing tools for Brownian dynamics analysis and light scatteringspectroscopy leads to a powerful system for research and application in numerous fields of science.

Construção e operação de um sistema de Motor controlado por luz ouro Nanorod Rotary

The possibility to generate and measure rotation and torque at the nanoscale is of fundamental interest to the study and application of biological and ...

Monitoring Conformational Dynamics of Single Unmodified Proteins using Plasmonic Nanotweezers

Current single-molecule techniques to characterize proteins typically require labels, tethers, or the use of non-native solution conditions. Such changes can alter protein biophysics and reduce the usefulness of the data acquired. Plasmonic nanotweezers is a technique that uses localized surface plasmon resonance (LSPR) on gold nanostructures to enhance the electric field within a confined hotspot region. This field enhancement allows for the use of low laser powers to trap single nanoparticles far smaller than conventional optical tweezers, down to only a few nanometers in diameter, such as single proteins. Trapping of single protein molecules within the hotspot region induces a shift in the local refractive index (nprotein &#62; nwater), altering light scattering as a product of the molecule&#39;s polarisability, which is affected by its volume, shape anisotropy, and refractive index. An avalanche photodiode (APD) collects the subsequent changes in light scattering. These alterations can then be analyzed to determine changes in the trapped molecule, including its size, global conformation, and dynamics of conformational change over time. The incorporation of microfluidics within the system allows for controlled environmental changes and real-time monitoring of their subsequent effects on the molecule. In this protocol, we demonstrate the steps to trap single protein molecules, alter their environmental solution conditions, and monitor their corresponding conformational changes using a plasmonic nanotweezers system.

Plasmonic nanotweezers use localized surface plasmon resonance in gold nanostructures to trap single nanoparticles, including proteins, within a nanometer-scale optical field. Changes in the scattered signal reveal protein presence and conformational dynamics, enabling monitoring without fluorophore modifications or surface tethering.

Monitoramento da dinâmica conformacional de proteínas únicas não modificadas usando pinças plasmônicas

Current single-molecule techniques to characterize proteins typically require labels, tethers, or the use of non-native solution conditions. Such changes ...

Optical Trapping of Plasmonic Nanoparticles for In Situ Surface-Enhanced Raman Spectroscopy Characterizations

Surface-enhanced Raman spectroscopy (SERS) enables the ultrasensitive detection of analyte molecules in various applications due to the enhanced electric field of metallic nanostructures. Salt-induced silver nanoparticle aggregation is the most popular method for generating SERS-active substrates; however, it is limited by poor reproducibility, stability, and biocompatibility. The present protocol integrates optical manipulation and SERS detection to develop an efficient analytical platform to address this. A 1064 nm trapping laser and a 532 nm Raman probe laser are combined in a microscope to assemble silver nanoparticles, which generate plasmonic hotspots for in situ SERS measurements in aqueous environments. Without aggregating agents, this dynamic plasmonic silver nanoparticle assembly enables an approximately 50-fold enhancement of the analyte molecule signal. Moreover, it provides spatial and temporal control to form the SERS-active assembly in as low as 0.05 nM analyte-coated silver nanoparticle solution, which minimizes the potential perturbation for in vivo analysis. Hence, this optical trapping-integrated SERS platform holds great potential for efficient, reproducible, and stable molecular analyses in liquids, especially in aqueous physiological environments.

Optical Trapping of Plasmonic Nanoparticles for In Situ Surface-Enhanced Raman Spectroscopy Characterizations

The present protocol describes a convenient approach to integrating optical trapping and surface-enhanced Raman spectroscopy (SERS) to manipulate plasmonic nanoparticles for sensitive molecular detection. Without aggregating agents, the trapping laser assembles plasmonic nanoparticles to enhance the SERS signals of target analytes for in situ spectroscopic measurements.

Captura óptica de nanopartículas plasmônicas para caracterizações de espectroscopia raman aprimoradas na superfície de Situ

Surface-enhanced Raman spectroscopy (SERS) enables the ultrasensitive detection of analyte molecules in various applications due to the enhanced electric ...