在ERC通过高级研究员格兰特HYMEM，由东风集团通过纳米系统倡议慕尼黑（NIM），并通过Sonderforschungsbereich（SFB1032）的资金支持，项目A8深表感谢。我们感谢博士亚历山大Ohlinger，博士溶胶卡雷特罗 - 帕拉西奥斯和水疗中心Nedev支持和富有成果的讨论。

1，实验装置<ol><li>使用向上向右显微镜和暗场油冷凝器用数值孔径（NA）= 1.2为暗视场照明。使用水浸物镜与100X的放大倍率和NA = 1.0颗粒的观察和捕捉。使用空气与目标10倍放大倍率和NA = 0.2遵循无节幼体的运动。 </li><li>使用光学镊子设置与1,064 nm的连续波激光器耦合到右上方显微镜。将光阱的激光功率为100毫瓦（与目标后，功率计测量）。 </li><li>使用CMOS高速相机或数码单镜头反光（DSLR）相机来检测和图像的金颗粒运动的光阱和无节幼体的运动。 </li><li>使用一个陷波滤波器，以防止激光进入相机。 </li><li>使用功率计的目标后，测量激光功率。 </li></ol> 2，样品制备</p&gt; <ol><li>吸取水滴（180微升）在显微镜载玻片上并在暗场显微镜的样品定位。 </li><li>从一个小水箱吸管无节幼体的水滴。 </li><li>使用10X空中目标，观察无节幼体的移动解决方案中，并录制视频流。 </li><li>使用金​​纳米颗粒的直径为60纳米的检测器，观察由无节幼体中产生的流体运动。因此，添加5微升的高度稀释的粒子溶液成水滴，使约1粒子可以在视图与100X水浸物镜的字段可以看出。 </li></ol> 3。粒子跟踪实验<ol><li>陷阱一金纳米粒子与光镊。因此，带来1,064 nm的激光捕获接近黄金纳米粒子，是解决在扩散通过移动显微镜载物台。迷人的光学力量拉金纳米粒子对日的焦点Ë激光束。被困粒子没有再扩散，而并保持其地位。采取被困纳米颗粒与数码单反相机的视频流以50赫兹进行30秒的帧速率。 </li><li>关闭光镊的激光，并从陷阱里放的金纳米粒子。 </li><li>使用粒子跟踪程序，以读出光学被困金颗粒在所述视频流的每个帧中的位置。粒子的XY位置随时间的快速傅立叶变换（FFT）揭示了一个频谱。 注：在这里，一个自写&#39;IGOR Pro的计算机程序代码来分析随着时间的推移和FFT分析在xy平面上的粒子中心的地位。 </li><li>作为替代自己编写的IGOR代码使用免费提供的“视频现场跟踪程序&#39;程序来跟踪颗粒的视频。使用商业软件&#39;起源&#39;来执行跟踪数据的傅立叶变换： <oL&gt; <li>视频文件拖到打开的程序的视频点跟踪“。 </li><li>鼠标点击出现在视频流和出现兴趣的圆形区域的第一图像的粒子。 </li><li>选择顶部的命令提示符窗口中的“对称”和“优化”来优化粒子的跟踪。 </li><li>鼠标点击“登录”，在top命令提示符窗口，然后选择一个文件夹来保存数据。跟踪数据将被保存为一个数据表格。 </li><li>鼠标点击“播放视频”关于跟踪程序的左边命令提示符窗口，并等待视频的所有帧进行了分析。 </li><li>关闭该程序，并与“起源”打开保存的数据的电子表格。设置列值“Y 1”和“y 2”。 </li><li>设定的时间步骤中的“产地”数据的电子表格的每个视频帧作为“×”。 </li><li>马克在 x位柱和在top命令提示符窗口中选择“数据分析”和“FFT”执行FFT。重复y位置栏的步骤。 </li><li>绘制所计算的FFT信号的振幅在x轴和y-方向相对于频率。 </li></ol></li></ol> 4。数值模拟<ol><li>通过使用计算机程序&#39;数学&#39;计算出60纳米金颗粒的极化率α。 <ol><li>使用等式（1）根据桑等人 16计算的极化。： <img alt="式（1）" fo:content-width="3in" src="/files/ftp_upload/51502/51502eq1.jpg" width="300" /> （1） </li><li>定义在该程序代码中的以下三个参数：金颗粒，所述纳米颗粒的半径，和周围介质的折射率的依赖于波长的复介电函数。 </li></ol></li><li>使用ELEC的描述。聚焦高斯光束根据Agayan 等[17]来计算作用在60纳米金颗粒的光学力量TRIC场分布： <img alt="公式2" fo:content-width="4in" src="/files/ftp_upload/51502/51502eq2.jpg" width="500" /> （2） <ol><li> 。用方程（3） - （6）从Agayan 等[17]来计算两者的梯度和散射作用在粒子力量： <img alt="式（3）" fo:content-width="3.5in" src="/files/ftp_upload/51502/51502eq3.jpg" width="350" /> （3） <img alt="公式4" fo:content-width="3in" src="/files/ftp_upload/51502/51502eq4.jpg" width="300" /> （4） <img alt="方程（5）" fo:content-width="5in" src="/files/ftp_upload/51502/51502eq5.jpg" width="500" /> （5） <img alt="公式6" fo:content-width="3in" src="/files/ftp_upload/51502/51502eq6.jpg" width="300" /> （6） </li><li>在程序代码中，定义参数为激光功率，邻数值孔径bjective，并且所述纳米颗粒的复合极化。 </li><li>总结梯度力和散射力来计算作用在光阱的金颗粒的总光力。 </li></ol></li><li>同时按住“控制”和“Enter”键运行仿真。 </li></ol>

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作者宣称，他们有没有竞争的财务权益。

暗场显微术是一种强大的工具，用于可视化的金纳米颗粒与下面的光学衍射极限的尺寸，由于金属纳米粒子的散射截面积超过它们的几何横截面（CP. 图2A）18。在镊子的设置，这种方法甚至允许区分如果仅在单个或多个金纳米颗粒被激光束俘获，因为颗粒之间的等离激元的耦合引起红移的等离子体激元共振频率15。暗视野显微镜与光学镊子的配置，因此提供了许多新的...

基于化学和生物指标的水质评价是具有根本的重要性，以获得对水生生态系统1-3的状态和环境条件的洞察力。经典方法化学水分析是基于感官特性或物理化学参数的测定。生物指标，而另一方面，是动物物种的存在和生存提供了环境条件和污染物，为发生英寸的指示作用的典型例子，一个生态系统的影响的洞察力是桡足类，一组小甲壳类水，它可以在几乎所有的水生境4,5找到。从水样品观察这些物质的活性和生存能力因此可用于获得关于一个生态系统5的整体条件的信息。桡足类的幼虫，这是所谓的无节幼体，用自己的触角节奏招（每个幼虫有三对appenda的GES在他们的头部区域）水6游泳。这招的频率和强度，从而在年龄，体格，动物7-10环境状况的直接指标。对这些标本的任何调查通常是用显微镜观察和直接计数的无节幼体的天线招完成。由于它们的大小（〜100-500微米）11，这通常要求要么逐个或定出一个单一的无节幼体在基板上做测量。 在这里，我们展示了一种新的方法利用光学被困金纳米粒子作为一种超灵敏探测器来观察桡足类幼虫的活性水样中。光镊通常由许多团体作为精细的实验工具，分子之间适用或测量力下降到piconewton范围12-14。最近，为光镊的应用范围已扩大到观察声波振动和解决NT波动在液体介质中通过监测纳米微粒的被局限在一个光学捕捉器15的运动。被浸没在液体颗粒进行布朗​​运动。内部光陷阱，然而，这项议案的一部分由一个强大的，激光诱导，梯度力衰减。因此，光学阱的刚度和颗粒内的激光束的焦点的定位可以通过将激光功率进行调整。在同一时间，也可以揭示关于俘获电位特性和分析分子与颗粒的相互作用通过在阱监测随时间变化的颗粒运动。这种方法使得可以拾取的频率，强度，和由一个移动的物体在其液体环境中产生的流体运动的方向。我们展示了如何这一般想法可以应用于以获得个体无节幼体的运动的频谱，而不要求直接干扰样品。这种实验方法引入了一个新概念，一般为水生标本的能动的行为在一个非常敏感的方式观察。有关指示生物种的观察，这可能会扩大现行方法进行水质分析，并可以适用于获得有关健康和水生生态系统的完整性信息。

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

我们展示了如何光镊可以提供一种灵敏的工具来分析由小的水生生物的运动所产生的流体振动。通过光镊举行一个单一的黄金纳米粒子作为传感器定量的水样在无节幼体幼虫（ 卤虫 ）的有节奏的运动。这是通过监测捕获纳米颗粒的时间相关的位移为无节幼体活动的结果来实现。纳米粒子的位置的傅立叶分析，然后产生一个频谱是特征观察到的物种的运动。该实验证明这种方法来测量和表征小的水生幼虫的活性而不需要直接观察它们，以获得关于相对于所述捕集粒子幼虫的位置信息的能力。总体而言，这种方法可以给在水生e实测值对某些物种的活力见识cosystem和可扩展的传统的方法，用于分析水样的范围内。

实验装置的示意图示于图1A中 。暗场配置是必要的，以光学检测为60nm的金颗粒的位移，在一个光学阱15。的1064纳米的捕集激光器中的波长被选择为保证检测器的金颗粒12,14的稳定禁闭。在显微镜的光束分离器是用来通过物镜聚焦俘获光束和一个陷波滤波器可以防止俘获激光进入实验的检测装置。无节幼体进行了变动，周围的光学被困金纳米粒子（ 图1B）?...

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

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

我们使用等离子体激元纳米颗粒的光学跟踪探测和表征水生生物的频率变动。

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 ...

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

Research

JoVE Journal

Engineering

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

10.4K 次观看.  Ludwig-Maximilians-Universität. 我们使用等离子体激元纳米颗粒的光学跟踪探测和表征水生生物的频率变动。 

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

Fabricating Metamaterials Using the Fiber Drawing Method

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

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

制造超材料使用光纤拉丝法

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

科研

工程学

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 ...

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

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

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

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

Patterning via Optical Saturable Transitions - Fabrication and Characterization

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

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

通过光学吸收跃迁图案 - 制备与表征

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

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

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

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

使用超声波润滑实验一压电辅助摩擦试验机和光学轮廓

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

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

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

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

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

多功能混合铁<sub&gt; 2</sub&gt; 0<sub&gt; 3</sub&gt; -Au纳米粒子高效的电浆暖气

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

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

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

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

电活性聚合物纳米粒子参展光热特性

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

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

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

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

牺牲纳米颗粒使用删除散粒噪声的影响通过电子束光刻装配式接触孔

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

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

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

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

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 ...

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

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

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

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

微流控成像流式细胞仪通过不对称检测时间延伸光学显微镜（ATOM）

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