Name: trapping of micro particles in nanoplasmonic optical lattice
Uploaded: 2017-09-05T12:30:00.000+00:00
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y.t.y. 愿意承认科技部在赠款数量最多 105-2221-007-MY3 和国立清华大学的资助支持下, 105N518CE1 和106N518CE1。

1. 光学设置 注意: 光学设置的原理见图 1 。
<ol> <li> 按照它们的手册设置光学镊子套件 (参见 材料表 ) 和荧光模块 (参见 材料表 )。将 470 nm 蓝光发光二极管 (LED) 光源连接至荧光模组. </li>
	<li> 更换高数值孔径 (na) (na = 1.25, 放大倍数 100x) 油浸目标由一个长的工作距离 (wd) 显微镜目标 (焦距3.6 毫米, wd = 10.6 毫米, NA = 0.5). </li>
	<li> 卸下组装套件的光束扩展段中的透镜, 以实现激光束的松散聚焦. </li>
	<li> 启用波长为 980 nm 的激光二极管的电源和电流, 并使用带电耦合器件 (CCD) 摄像机来确保激光束正确对准. 
	注: 如果激光束是定向的, CCD 摄像机将会读取一个高斯点. </li>
</ol> 2。纳米 <ol> <li> 标记制作. 
	注意: 标记将有助于在制造过程和随后的陷印实验中定位 nanoplasmonic 阵列。详细的过程在 补充图 1 中说明。
	<ol> <li> 在厚度为 0.17 mm 的片上沉积 40 nm 氧化铟锡 (ITO) 薄膜. 
		注: ITO 薄膜将有助于在随后的电子束光刻过程中释放电子. </li>
		<li> 自旋涂层8和 #181; m 层的正光刻胶与自旋速度 4000 rpm 和时间三十年代与旋转涂布机. </li>
		<li> 软烘烤样品在90和 #176; C 为 5 min, 并将样品与掩对齐, 并将样品暴露于八十年代的 UV 光器. </li>
		<li> 将样品浸泡在光刻胶显影液中 130s. </li>
		<li> 使用热蒸发将2纳米铬层和一层40纳米的金沉积在样品上。 18 </li> <li> 将样品浸泡在丙酮中, 并将其放置在43赫和 150 W 的超声波清洗器中, 以进行5分钟的升降。
	</ol> </li> <li> 制作 Nanoplasmonic 阵列 <ol> <li> 自旋涂层一层电子束抗 PMMA 120K, 自旋速度 5000 rpm 三十年代在旋转涂布机。烘烤样品在160和 #176; C 为3分钟在一个热的盘子. </li>
		<li> 自旋涂层的另一层电子束抵御 PMMA 960K 与自旋速度 5000 rpm 三十年代在一个旋转涂布机。烘烤样品在160和 #176; C 为3分钟在一个热的盘子. </li>
		<li> 使用电子束写入器以加速电压30伏和剂量 400 C/cm 2 来公开电子束抵抗. </li>
		<li> 在热蒸发器中沉积40纳米金层. </li>
		<li> 将样品浸泡在丙酮中, 并将其放在超声波清洗机中5分钟以进行升降. </li>
	</ol> </li> </ol> 3。样品冷却系统及其温度标定 注意: 在 补充图 2 中显示了示例冷却阶段的设计. 
<ol> <li> 为采样冷却的驱动程序电路 <ol> <li> 将电阻、双极结点晶体管和电源金属氧化物场效应晶体管放在自定义电路板上, 按照 补充图3中的电路图进行操作.用烙铁焊接所有这些部件. </li>
		<li> 连接电路板控制端口和电子控制板之间的导线。连接电路板的输出端口和热电冷却 (TEC) 元件之间的导线。将 TEC 元素放在样品台上, 并热沉. 
		#8203; 注意: TEC 元素在中心有一个孔, 允许激光束通过. </li>
		<li> 将电路板上的导线连接到 5 V 电源。使用 forward-looking 红外摄像机监视温度以检查热电冷却是否正确冷却. </li>
	</ol> </li> <li> forward-looking 红外摄像机和电阻温度检测器 (RTD) 温度计中测量温度的校准。
	<ol> <li> 将 rtd 温度计放在空白片上, 并在其上应用少量的热贴, 以确保 rtd 温度计和片之间有适当的热接触. </li>
		<li> 通过改变脉冲宽度调制设置的占空比, 将电子控制电路的输出功率设置更改为 TEC 元件, 并等待3分钟, 以确保达到稳定状态温度。使用 RTD 温度计读取温度. </li>
		<li> 打开前瞻式红外摄像机并监视温度。重复这个在不同的输出功率设置, 以获得温度校准曲线。有代表性的温度校准曲线显示在 补充图 4 中. 
		注意: 在 RTD 温度计和前向红外摄像机之间进行校准是至关重要的, 因为 forward-looking 红外摄像机的温度读数必须准确, 以确保达到正确的温度. </li>
	</ol> </li> </ol> 4。微粒捕集 <ol> <li> 将直径2和 #181 的微聚苯乙烯微粒稀释在去离子水中, microcentrifugetube 具有适当容积率. 
	注: 微颗粒浓度可根据实验目的进行调整。较低浓度允许单粒子俘获事件的采样时间间隔, 较高浓度将缩短多粒子捕获的时间。对于单粒子俘获, 典型浓度为 ~ 0.05% (w/v). </li>
	<li> 将样品与 nanoplasmonic 阵列放在舞台上, 并打开 470 nm LED 作为荧光光源, 并手动将功率设置为5兆瓦的明亮场成像. </li>
	<li> 使用标记来定位 nanoplasmonic 阵列, 对齐样本, 并使用 CCD 摄像机确保阵列位于计算机屏幕上的感兴趣区域的中心. </li>
	<li> 免除10和 #181; L 对直径2和 #181 的稀释微粒子进行取样, 并在样品上使用微吸管. </li>
	<li> 打开当前电源到波长 980 nm 的激光二极管以激发阵列的浆共振, 其功率范围为1兆瓦至10兆瓦. </li>
	<li> 手动打开电子控制板上的电源以使样品冷却至稳定状态温度〜4和 #176; C. </li>
	<li> 在查看器软件中, 单击 #34; 录制视频和 #34; 序列以打开录制对话框。单击 "#34"; 记录和 #34; 按钮启动视频录制1.5 的微粒子的运动的帧速率为10帧/秒的影响下, 激光光束使用 CCD 相机。单击 #34; 停止和 #34; 按钮以停止录制。请参见 视频 1 . </li>
</ol>

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作者没有什么可透露的。

此处描述的过程使读者能够可靠地每天复制陷印。一个通用的经验指南, 设计一个可用的晶格是使用一个可比大小的浆阵, interdisc 距离, 和被困粒子的大小。与单一的, 孤立的浆纳米结构相结合, 光学晶格设计与高光功率所提供的冷却样品到〜4° c 使用, 大大提高了捕获概率。如果分离性好, 浆纳米结构被用作诱捕点, 你需要等待很长时间才能将微粒迁移到浆纳米结构附近的有效俘获体积中。同时, 增...

微尺度微粒的光学捕获最初是由亚瑟在二十世纪七十年代代初提出的。自其发明以来, 该技术已被开发为微型和纳米1,2的多功能工具。传统的基于远场聚焦原理的光阱, 其空间约束中的衍射固有地受到限制, 其中俘获力显著减小 (在一个半径为粒子的a3定律之后)a)3. 为了克服这种衍射极限, 研究人员利用浆金属纳米结构, 开发了基于倏逝光场的近场光学俘获技术, 此外, 将纳米级物体捕获到单蛋白分子已被证明4,5,6,7,8,9,10,11。此外, 浆光学晶格是由周期性浆纳米结构的阵列创建的, 以赋予微纳米粒子和多粒子堆叠的长距离传输11,12。在光学晶格中干扰俘获的一个主要障碍是光热对流, 并已努力通过几个组14、15、16、17来阐明其效果。使用格林函数, Baffou et al.通过将每个浆纳米结构建模为点加热器来计算温度剖面, 然后通过实验验证了它们的模型14。汤森的小组也测量了等离子体诱导对流的粒子测速仪15。作者的小组也描绘了近场和对流运输并且显示了一项工程战略抑制光热对流16,17。
在这里, 我们提出了一个光学装置的设计和详细的程序, 专门用于诱捕实验浆光学晶格。光的潜力是通过照亮一组金 nanodiscs 与一个松散的聚焦高斯光束。这里还描述了一种通过将样品冷却到低温 (~ 4 ° c) 来抑制光热对流以获得最佳捕获的方案, 这里也介绍了17。在方程近似下, 由 u ~l2 gβΔT / v给出了自然对流速度u的数量级估计, 其中L是热源的长度刻度, δT是由于加热而引起的相对于参照的温度升高。 g和β分别是重力加速度和热膨胀系数。在接近4° c 的温度下, 水介质的密度表现出反常的温度依赖性, 这就转化为近零的热膨胀系数, 因此, 微乎其微小的光热效应对流。

<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

为了克服传统远场光学镊子的衍射极限, 研制了浆光学镊子。浆光学晶格由一组纳米结构组成, 它表现出各种俘获和传输行为。我们报告的实验程序, 捕获微粒子在一个简单的正方形 nanoplasmonic 光学晶格。我们还描述了 nanoplasmonic 阵列的光学设置和纳米。光学电位是通过照亮一组 980 nm 波长的高斯光束和令人兴奋的等离子体共振的金 nanodiscs 来产生的。通过荧光成像对颗粒的运动进行监测。此外, 还描述了一种抑制光热对流的方案, 以增加可用的光学功率, 从而获得最佳捕获。通过将试样冷却到低温, 并利用水介质的近零热膨胀系数, 实现了对流的抑制。这里报告了单粒子传输和多粒子捕获。

在我们的实验中记录了一个 CCD 摄像机的单粒子轨迹, 然后用一个自定义程序来处理图像, 以提取每个粒子的轨迹16。有代表性的结果显示在图 3 和视频 1中, 直径为2µm 的微球体. 观察了光学晶格内的多个粒子的修饰。从粒子的代表性运动视频中提取的连续图像显示在图 4中。对于直径2µm 的微粒, 可?...

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

我们描述了在 nanoplasmonic 光学晶格中光阱微粒子的过程。

Nanoplasmonic 光学晶格中微粒子的俘获

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 次观看.  National Tsing Hua University. 我们描述了在 nanoplasmonic 光学晶格中光阱微粒子的过程。

视频: 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.

纳米粒子的光学捕获

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 ...

科研

工程学

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.

三维光学分辨率的光声显微镜

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

生物工程

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.

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

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.

分析无节幼体的运动“<em&gt;卤虫</em&gt;&#39;由电浆纳米粒子的光学跟踪

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.

一个纳米光输送带的制作和操作

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.

介电微粒的光阱装载在空气中

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.

电浆捕获和纳米粒子的释放在监控环境

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.

轻型金纳米旋转电机系统的施工与运行

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.

使用等离子体纳米镊子监测单个未修饰蛋白质的构象动力学

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.

等离子体纳米颗粒的光学捕获用于 原位 表面增强拉曼光谱表征

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

Nanoplasmonic 光学晶格中微粒子的俘获

摘要

探索更多视频

此视频中的章节

纳米粒子的光学捕获

三维光学分辨率的光声显微镜

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

分析无节幼体的运动“

一个纳米光输送带的制作和操作

介电微粒的光阱装载在空气中

电浆捕获和纳米粒子的释放在监控环境

轻型金纳米旋转电机系统的施工与运行

使用等离子体纳米镊子监测单个未修饰蛋白质的构象动力学

等离子体纳米颗粒的光学捕获用于原位表面增强拉曼光谱表征

Nanoplasmonic 光学晶格中微粒子的俘获

摘要

探索更多视频

此视频中的章节

纳米粒子的光学捕获

三维光学分辨率的光声显微镜

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

分析无节幼体的运动“

一个纳米光输送带的制作和操作

介电微粒的光阱装载在空气中

电浆捕获和纳米粒子的释放在监控环境

轻型金纳米旋转电机系统的施工与运行

使用等离子体纳米镊子监测单个未修饰蛋白质的构象动力学

等离子体纳米颗粒的光学捕获用于 原位 表面增强拉曼光谱表征

等离子体纳米颗粒的光学捕获用于原位表面增强拉曼光谱表征