Name: construction and operation of a light-driven gold nanorod rotary motor system
Uploaded: 2018-06-30T14:30:00.000+00:00
Duration: 9 min 48 s
Description: Watch this Scientific Journal Video about Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System at JoVE.com

这项工作得到了克努特和爱丽丝拉乌尔·沃伦贝格基金会、瑞典研究委员会和先进纳米和纳米技术领域的支持。

1. 纳米粒子旋转用圆极化光镊
<ol><li>建立一个适当的倒置显微镜周围的设置, 并使用可见光红波长激光 (660 nm)。图 2给出了实验设置的示意图。确保选择一个稳定的输出功率高达500兆瓦的激光器 (产生功率在样品平面约50兆瓦)。还要确保其他组件在捕获激光波长下表现良好。</li>
	<li>使用具有0.95 和40X 放大倍数的数值孔径 (NA) 的干目标。</li>
	<li>始终佩戴安全护目镜, 保持良好的激光安全 (特别是如果使用非可见光激光器)。对最小激光功率进行对准。封装整个激光路径的安全和避免热漂移和灰尘的光路。 注: 根据激光输出的偏振态, 光镊可以从放置一个线性偏光片作为初始光学元件中受益。如果激光器的极化已经是线性的, 则可以省略这个分量。</li>
	<li>在 Keplerian 望远镜配置中使用一对正透镜 (图 2底部的透镜) 来扩展激光光束, 使光束直径比陷印目标的后隙稍大。 注意: 这使得使用整个 NA 的目标, 并将产生一个衍射有限的焦点的陷阱11, 导致最佳的陷井刚度。</li>
	<li>确保在光束膨胀器后, 俘获激光器正确地准直。这可以通过确保光束尺寸在传播到目标 (或使用剪切干涉仪) 时接近不变。</li>
	<li>使用两个镜像 (图 2中的 M1 和 M2), 安装在运动镜像支架上 (如果需要, 转换阶段), 将激光束定向到显微镜设置中。 注 1: 在激光镜和显微镜之间保持足够的空间, 以便能够添加额外的光学元件, 如 waveplates 和分光镜。 注 2: 确保激光始终从显微镜下的眼睛或任何其它可接触的光线中过滤掉。</li>
	<li>使用一个 beamsplitter (50/50 部分传输/反射在这里使用, 但一个分色也可以正常工作) 显微镜内, 以耦合激光到目标, 而不失去成像和测量能力的显微镜设置。</li>
	<li>在安装过程中包括照相机 (见图 2), 以便随后进行实验观察和数据记录。如果没有眼睛的系统使用, 这是至关重要的任何对齐。</li>
	<li>把激光聚焦在玻璃滑梯或镜子上。如果激光对准并以正确的角度进入目标, 则在焦点的上方和下方改变焦距时, 激光强度模式是径向对称的。</li>
	<li>微调激光镜的角度 (图 2中的 M1 和 M2) 以获得最佳的激光对准 (如1.9 所述)。</li>
	<li>圆极化激光光。<ol>
<li>在目标的光路, 通过激光通过一个季度波板 (QWP; λ/4 在图 2) 以它的快速轴在45°到激光的线性极化, 将线性偏振光转换成圆极化光在样本平面。</li>
		<li>在目标前面设置360°旋转的线性偏光片和功率计。</li>
		<li>通过旋转线性偏振器来检查极化, 并注意最大和最小功率, 对应于主轴或偏振椭圆。 注: 最佳旋转性能的比值应高于0.9。如果未达到此项, 请参阅步骤4.2 中的解决方案。</li>
	</ol>
</li>
	<li>测量样品平面上的激光功率。<ol>
<li>使用光学功率计在样品平面上探测激光功率。小心收集所有的光通过的目标, 以正确的测量诱捕能力。</li>
		<li>对输出激光功率进行线性扫描, 并在样本平面上记录相应的功率, 以便随后转换为陷阱中的幂密度。</li>
	</ol>
</li>
	<li>在霍斯特·科勒照明中设置一个暗场 (DF) 系统, 使用油浸式 DF 冷凝器, 以实现粒子和捕获事件的可视化。这将允许对被困纳米粒子的成像和光谱测量。</li>
</ol>2. 测量旋转、旋转布朗动力学和光谱特性的仪器
<ol><li>使用单像素探测器的光子相关光谱学。<ol>
<li>将 beamsplitter (30 r/70 t) 插入到光学路径中, 以便从纳米微粒中提取散射光。</li>
		<li>将快速的单像素 Si 光电二极管连接到数据采集卡, 以启用信号的记录。 注意: 重要的是有一个光电二极管/数据采集仪, 能够测量的旋转频率预期 (几赫)。</li>
		<li>将光源聚焦在xy平移装载中固定的集合光纤上。在收集纤维之前插入一个线性偏光片。</li>
		<li>为收集纤维对齐, 一对可见光到出口端的纤维照亮基体。这允许对光纤的收集区域进行可视化和分析。</li>
		<li>使用xy平移安装调整光纤的位置, 使其采集区域与光阱的位置重合。将光纤的出口端连接到 Si 探测器, 微调光纤的位置, 以最大限度地收集回分散信号。</li>
	</ol>
</li>
	<li>暗场光谱学设置。<ol>
<li>请记住, 在选择样品和光谱仪之间的路径中的所有光学元件时需要注意, 以免在感兴趣的光谱范围内阻挡光线。</li>
		<li>注意, 直接散射和/或反射激光可能会损坏光谱仪传感器。使用适当的过滤器和/或分色分光镜来阻挡激光光源。始终在最小激光功率上执行对齐设置。</li>
		<li>在光学路径中插入 beamsplitter/镜像以将光重定向到光谱仪 (在此协议中, 使用自由空间耦合光谱仪)。如果合适, 还可以使用显微镜输出端口之一。</li>
		<li>使用凹槽过滤器去除强烈的陷波激光 (在我们的情况下需要足够的堵塞在激光波长总 OD12 的过滤器), 在其他情况下将掩盖感兴趣的微粒的光谱反应。</li>
		<li>用导镜 (图 2中的 M1 和 M2) 调整光镊的位置, 使其与光谱仪狭缝的位置重合。 注 1: 光阱位置的变化将需要重新调整光子相关测量系统 (指令 2.1. 4-2. 1.5)。 注 2: 在光学镊子的新位置, 指令 1.9-1.10 需要重复, 以达到一个良好的对准光学陷阱。</li>
	</ol>
</li>
</ol>3. 实验程序
<ol><li>实验用粒子的制备。<ol>
<li>在水中稀释微粒。适当的纳米棒浓度应在 0.1-0.01 pM 之间的范围内。油脂实验在超声波清洗剂浴中稀释溶液2分钟, 分解可能的骨料和融汇溶液。</li>
		<li>调整纳米棒在稀释中的浓度, 以避免捕获多个粒子。实验完成的时间越长, 降低捕获多个粒子或污染物的风险所需的浓度就越低。</li>
	</ol>
</li>
	<li>样品细胞的制备。<ol>
<li>分别在丙酮和随后的异丙醇下超声波五分钟, 清洗显微镜滑梯和盖玻璃 (1.5 号)。 注: 确保在实验过程中玻璃滑动的表面电荷与胶体纳米粒子具有相同的极性。表面活性剂铵溴化物 (CTAB) 稳定的纳米粒子正向电荷。</li>
		<li>将100µm 间隔胶带放在玻璃滑梯上。</li>
		<li>分散2µL 的稀释纳米微粒溶液在显微镜下的幻灯片在井和2µL 在盖子玻璃上。在这两个曲面上的解决方案都允许对样本单元进行更可控制的装配。</li>
		<li>将样品单元的两部分连接在一起, 同时避免在腔内形成气泡。</li>
		<li>将细胞放在显微镜的舞台上, 将一滴指数匹配 (浸入) 油放在样品的顶端, 在冷凝器上放一滴。每一侧的水滴避免油中的气泡散射光, 减少 DF 照明的对比度。</li>
	</ol>
</li>
	<li>执行实验。<ol>
<li>在 DF 成像系统中通过观察找到粒子。一个单一的纳米通常可以通过观察它的布朗运动 (比骨料更不稳定) 和颜色 (对应于最强的 LSPR 共振) 来识别。</li>
		<li>启动/取消阻止陷印激光器。</li>
		<li>通过一系列的舞台运动和聚焦校正, 将所选粒子通过辐射压力推入到水玻璃界面的激光传播方向。在界面上, z运动受辐射压力和纳米粒子表面 CTAB 分子之间库仑斥力和正电荷表面的平衡的制约。xy涨落受光镊中梯度力的限制。</li>
		<li>通过小的焦点校正, 最大限度地利用自相关数据 (如指令3.4 中所述) 来衡量捕获稳定性或旋转速度。</li>
		<li>此时, 记录被困纳米的旋转动力学和光谱性质。有关如何探测这些信息, 请参见下面的说明3.4 和3.5。这可以在较长的时间内完成, 如果需要, 可长达几个小时。</li>
	</ol>
</li>
	<li>旋转动力学测量。<ol>
<li>一定要有一个收集区域从纤维足够大, 总是附上粒子的图像在其平移运动。</li>
		<li>在适当的探测频率和采集时间内采集硅光电探测器的强度振荡信号。选择65536赫兹和1的采集时间开始和调整, 如果需要的话。 注: 探测频率应至少为两个 (最佳十) 倍, 大于旋转频率乘以可检测旋转对称度 (N, 见下文)。收集时间应该足够长, 能够获得比旋转频率明显低的频率。</li>
		<li>从旋转纳米粒子收集了一组强度波动数据后, 计算了强度波动的自相关。这是通过计算每个延迟时间τ (即 C(τ) = {i(τ)的时间延迟拷贝的信号的相关性来完成的。I(0)})。</li>
		<li>对理论自相关函数进行拟合 <img alt="Equation 1" src="/files/ftp_upload/57947/57947eq1v2.jpg"> 其中i0是平均强度, i1是强度波动的振幅, N 是可检测的旋转对称度 (对于棒状粒子 N=2)2,3。</li>
		<li>从拟合中提取自相关信号τ0的旋转频率f腐烂和衰减时间 (与旋转布朗运动动力学有关)。</li>
	</ol>
</li>
	<li>光谱测量。<ol>
<li>通过收集光照光, 记录一个白色的光谱 (I白色(λ))。这可以通过浓密分散均匀散射聚苯乙烯珠在表面和收集它们的散射响应。</li>
		<li>记录一个背景光谱 (Ibkg(λ)) 收集的杂散光在捕获点时, 粒子没有被困。 注 1: 这应该为每个单独的测量, 因为背景属性可能会在不同的样本细胞之间, 甚至在样本中的位置差异很大。 注 2: 记录背景谱应用于用于光阱的相同激光功率。这使得人们可以从玻璃滑块中去除任何可能的自动荧光, 因为焦点中的高激光强度激发了它。</li>
		<li>记录一个黑暗的频谱 (我黑暗(λ)), 当阻止所有的光来到探测器。然后, 记录一个被捕获的纳米微粒的原始光谱 (I生(λ))。</li>
		<li>通过计算获得实际的纳米粒子散射谱 <img alt="Equation 2" src="/files/ftp_upload/57947/57947eq2v2.jpg">
</li>
		<li>为了提取 LSPR 峰值位置的信息, 用双洛伦兹拟合函数 (包括带间跃在黄金中的过渡的线性修正项) 拟合出能量尺度中的 DF 散射谱。模型函数读取: <img alt="Equation 3" src="/files/ftp_upload/57947/57947eq3v2.jpg"> 那里E是能量, IB是基线强度, k斜率的线性校正, i我是强度极大值, Γi全宽在半极大值 (FWHM) 和E0, I两个洛伦兹峰的峰值位置。</li>
	</ol>
</li>
</ol>4. 常见问题的排除和解决方法
<ol><li>与金纳米性质有关的问题。<ol>
<li>陷印稳定性差。<ol>
<li>确保主共振 (通常情况下, 纳米棒的纵向共振) 是在激光波长的蓝色波长边。如果没有, 梯度力将成为排斥, 而不是吸引力37。</li>
			<li>随着纳米尺寸的减小, 运动从布朗波动增加, 同时稳定力从斯托克斯阻力减少。确保纳米棒足够大的xy梯度力, 以克服这些破坏稳定的力量。</li>
		</ol>
</li>
		<li>重叠或广泛的光谱特征。<ol>
<li>杆需要有一个足够大的纵横比为 LSPR 峰被充分分离, 以单独解决 (见图 1b)。 注: 激光波长对形状各向异性施加上限, 因为纵向 LSPR 红移长棒。</li>
			<li>在可见的体制中, 纳米粒子最好是足够小到不支持高阶 LSPR 模式, 因为这使得分析复杂化。在4.1.1.2 中, 纳米粒子的选择是这一考虑与陷印稳定性问题之间的一种平衡。</li>
		</ol>
</li>
	</ol>
</li>
	<li>陷印激光器的圆极化不足。 注: 为了获得捕获的纳米微粒的最佳旋转性能, 应将激光到达试样平面的光圆极化。分光镜和其他光学元件可以是极化依赖性, 这可能使它不可能获得完美的圆极化只使用一个 QWP。<ol>
<li>插入半波板 (HWP;图 2中的λ/2) 后, QWP 在路径中, 以补偿 beamsplitter 双折射。</li>
		<li>设置线性偏振器和功率表配置, 并对激光的偏振态进行分析 (如指令 1.11.2-1.11.3)。</li>
		<li>对于每个位置的增量为五度的 QWP, 旋转 HWP 通过其整个角范围 (90°) 的步骤五度, 并测量每个位置的功率比。努力找出 QWP 和 HWP 的角度, 最大限度地提高最大和最小功率的比值。 注: 根据我们的经验, 最大和最小功率之间的最大比率是 0.75, 没有和0.98 的 HWP 校正。</li>
	</ol>
</li>
	<li>在激光功率下粘接界面的粒子不足以限制xy平面中的粒子。<ol>
<li>调整稳定剂的浓度, 通过粒子洗涤程序和随后再分散的纳米棒在控制浓度的 CTAB。<ol>
<li>将纳米粒子的库存溶液离心至颗粒沉积物 (在600g 时为5分钟)。</li>
			<li>卸下悬浮液。</li>
			<li>在水中重新分散。这稀释了库存解决方案的 CTAB 内容。</li>
			<li>重复步骤4.3.1.1。和4.3.1.2。再来一次。 注: 由于 CTAB 的作用是胶体稳定剂, 避免过度的离心时间和速度在后续洗涤步骤, 因为聚集的风险增加, 因为 CTAB 被冲走。</li>
			<li>最初的胶体溶液中的大多数 CTAB 表面活性剂现在被去除, 并且一个新的、控制良好的 CTAB 浓度可以引入胶体。从我们的经验, 分散在水中的股票溶液与20µM 的 CTAB 和随后的二次水稀释到实验溶液浓度的结果, 表面覆盖, 产生足够的库仑排斥。</li>
			<li>可能需要微调 CTAB 浓度, 以创造适当的粒子/表面斥力, 为特定批次的纳米粒子使用。迭代上述过程, 并稍微改变 CTAB 浓度, 以找到一个合适的。</li>
		</ol>
</li>
		<li>玻璃表面清洗到负电荷表面。 注: 这个洗涤过程产生一个负电荷表面, 将被涂上自由 CTAB 分子在实验解决方案, 使它积极和静电排斥粒子在2D 陷印。<ol>
<li>采取显微镜幻灯片和清洁它的混合物水和 2 wt% 的基本洗涤剂加热到80°c 约10分钟, 直到表面明显亲水性。 注: 避免清洗玻璃幻灯片太长或苛刻, 因为这可以使玻璃表面多孔和产生大量的污染粒子。</li>
		</ol>
</li>
	</ol>
</li>
	<li>光子自相关光谱学存在的问题。<ol>
<li>强度振荡或噪声信号的低振幅。<ol>
<li>在采集光纤前插入带通滤波器 (如图 2中的 BP 滤波器), 通过激光光并阻挡暗场光照光。 注意: 原则上, 测量工作时, 收集所有的光以及。然而, unpolarized 白光 DF 照明有效地激发出的平面模式, 因为纳米旋转约其短轴在平面正常到光轴, 这是平面横向 LSPR。这种模式在旋转过程中不携带任何形状的各向异性, 从它收集光只会降低测量的信噪比。</li>
		</ol>
</li>
		<li>自相关函数的附加衰减。<ol>
<li>确保收集纤维的核心尺寸足够大, 以包含纳米粒子的图像在所有的游览期间由于平移布朗运动。</li>
			<li>如果使用太小的核心尺寸的光纤, 请将其替换为较大的纤维。</li>
			<li>检查新纤维的对齐方式, 如指令 2.1. 4-2. 1.5。</li>
		</ol>
</li>
	</ol>
</li>
</ol>

<ol>
	<li>Andr&#233;n, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+photothermal+effects+on+optically+trapped+gold+nanorods+by+simultaneous+plasmon+spectroscopy+and+brownian+dynamics+analysis.">Probing photothermal effects on optically trapped gold nanorods by simultaneous plasmon spectroscopy and brownian dynamics analysis.</a> ACS Nano. 11 (10), 10053-10061 (2017).</li><li>Shao, L., Yang, Z. -. J., Andr&#233;n, D., Johansson, P., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanorod+rotary+motors+driven+by+resonant+light+scattering.">Gold nanorod rotary motors driven by resonant light scattering.</a> ACS Nano. 9 (12), 12542-12551 (2015).</li><li>Lehmuskero, A., Ogier, R., Gschneidtner, T., Johansson, P., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+spinning+of+gold+nanoparticles+in+water+using+circularly+polarized+light.">Ultrafast spinning of gold nanoparticles in water using circularly polarized light.</a> Nano Letters. 13 (7), 3129-3134 (2013).</li><li>&#352;&#237;pov&#225;, H., Shao, L., Odebo L&#228;nk, N., Andr&#233;n, D., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photothermal+DNA+release+from+laser-tweezed+individual+gold+nanomotors+driven+by+photon+angular+momentum.">Photothermal DNA release from laser-tweezed individual gold nanomotors driven by photon angular momentum.</a> ACS Photonics. , (2018).</li><li>Hajizadeh, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brownian+fluctuations+of+an+optically+rotated+nanorod.">Brownian fluctuations of an optically rotated nanorod.</a> Optica. 4 (7), 746-751 (2017).</li><li>Tong, L., Miljkovic, V. D., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alignment,+rotation,+and+spinning+of+single+plasmonic+nanoparticles+and+nanowires+using+polarization+dependent+optical+forces.">Alignment, rotation, and spinning of single plasmonic nanoparticles and nanowires using polarization dependent optical forces.</a> Nano Letters. 10 (1), 268-273 (2009).</li><li>Lehmuskero, A., Li, Y., Johansson, P., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmonic+particles+set+into+fast+orbital+motion+by+an+optical+vortex+beam.">Plasmonic particles set into fast orbital motion by an optical vortex beam.</a> Optics Express. 22 (4), 4349-4356 (2014).</li><li>Lehmuskero, A., Johansson, P., Rubinsztein-Dunlop, H., Tong, L., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+trapping+of+colloidal+metal+nanoparticles.">Laser trapping of colloidal metal nanoparticles.</a> ACS Nano. 9 (4), 3453-3469 (2015).</li><li>Shao, L., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-driven+rotation+of+plasmonic+nanomotors.">Light-driven rotation of plasmonic nanomotors.</a> Advanced Functional Materials. , (2018).</li><li>Ashkin, A., Dziedzic, J. M., Bjorkholm, J., 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> Optics letters. 11 (5), 288-290 (1986).</li><li>Neuman, K. C., Block, S. M. <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.">Optical trapping.</a> Review of scientific instruments. 75 (9), 2787-2809 (2004).</li><li>Chu, S., Hollberg, L., Bjorkholm, J. E., Cable, A., Ashkin, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+viscous+confinement+and+cooling+of+atoms+by+resonance+radiation+pressure.">Three-dimensional viscous confinement and cooling of atoms by resonance radiation pressure.</a> Physical Review Letters. 55 (1), 48 (1985).</li><li>Svoboda, K., Block, S. M. <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+metallic+Rayleigh+particles.">Optical trapping of metallic Rayleigh particles.</a> Optics Letters. 19 (13), 930-932 (1994).</li><li>Wang, M. D., Yin, H., Landick, R., Gelles, J., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stretching+DNA+with+optical+tweezers.">Stretching DNA with optical tweezers.</a> Biophysical journal. 72 (3), 1335-1346 (1997).</li><li>Friese, M. E. J., Nieminen, T. A., Heckenberg, N. R., Rubinsztein-Dunlop, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+alignment+and+spinning+of+laser-trapped+microscopic+particles.">Optical alignment and spinning of laser-trapped microscopic particles.</a> Nature. 394 (6691), 348-350 (1998).</li><li>Gao, W., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+micro/nanomotors+in+drug+delivery.">Synthetic micro/nanomotors in drug delivery.</a> Nanoscale. 6 (18), 10486-10494 (2014).</li><li>Li, M., Lohm&#252;ller, T., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+injection+of+gold+nanoparticles+into+living+cells.">Optical injection of gold nanoparticles into living cells.</a> Nano Letters. 15 (1), 770-775 (2014).</li><li>Nelson, B. J., Kaliakatsos, I. K., Abbott, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microrobots+for+minimally+invasive+medicine.">Microrobots for minimally invasive medicine.</a> Annual review of biomedical engineering. 12, 55-85 (2010).</li><li>Balk, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kilohertz+rotation+of+nanorods+propelled+by+ultrasound,+traced+by+microvortex+advection+of+nanoparticles.">Kilohertz rotation of nanorods propelled by ultrasound, traced by microvortex advection of nanoparticles.</a> ACS Nano. 8 (8), 8300-8309 (2014).</li><li>Chen, H., Shao, L., Li, Q., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanorods+and+their+plasmonic+properties.">Gold nanorods and their plasmonic properties.</a> Chemical Society Reviews. 42 (7), 2679-2724 (2013).</li><li>Maier, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Plasmonics: fundamentals and applications. , (2007).</li><li>Xu, H., Bjerneld, E. J., K&#228;ll, M., B&#246;rjesson, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectroscopy+of+single+hemoglobin+molecules+by+surface+enhanced+Raman+scattering.">Spectroscopy of single hemoglobin molecules by surface enhanced Raman scattering.</a> Physical Review Letters. 83 (21), 4357 (1999).</li><li>Chen, H., Kou, X., Yang, Z., Ni, W., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape-and+size-dependent+refractive+index+sensitivity+of+gold+nanoparticles.">Shape-and size-dependent refractive index sensitivity of gold nanoparticles.</a> Langmuir. 24 (10), 5233-5237 (2008).</li><li>Ruijgrok, P. V., Verhart, N. R., Zijlstra, P., Tchebotareva, A. L., Orrit, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brownian+fluctuations+and+heating+of+an+optically+aligned+gold+nanorod.">Brownian fluctuations and heating of an optically aligned gold nanorod.</a> Physical Review Letters. 107 (3), 037401 (2011).</li><li>Pelton, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+trapping+and+alignment+of+single+gold+nanorods+by+using+plasmon+resonances.">Optical trapping and alignment of single gold nanorods by using plasmon resonances.</a> Optics Letters. 31 (13), 2075-2077 (2006).</li><li>Hansen, P. M., Bhatia, V. K., Harrit, N., Oddershede, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expanding+the+optical+trapping+range+of+gold+nanoparticles.">Expanding the optical trapping range of gold nanoparticles.</a> Nano Letters. 5 (10), 1937-1942 (2005).</li><li>Ni, W., Ba, H., Lutich, A. A., J&#228;ckel, F., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancing+Single-Nanoparticle+Surface-Chemistry+by+Plasmonic+Overheating+in+an+Optical+Trap.">Enhancing Single-Nanoparticle Surface-Chemistry by Plasmonic Overheating in an Optical Trap.</a> Nano Letters. 12 (9), 4647-4650 (2012).</li><li>Liu, M., Zentgraf, T., Liu, Y., Bartal, G., Zhang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-driven+nanoscale+plasmonic+motors.">Light-driven nanoscale plasmonic motors.</a> Nature nanotechnology. 5 (8), 570-573 (2010).</li><li>Neale, S. L., MacDonald, M. P., Dholakia, K., Krauss, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All-optical+control+of+microfluidic+components+using+form+birefringence.">All-optical control of microfluidic components using form birefringence.</a> Nature Materials. 4 (7), 530-533 (2005).</li><li>Jones, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rotation+detection+in+light-driven+nanorotors.">Rotation detection in light-driven nanorotors.</a> ACS Nano. 3 (10), 3077-3084 (2009).</li><li>Bonin, K. D., Kourmanov, B., Walker, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+torque+nanocontrol,+nanomotors+and+nanorockers.">Light torque nanocontrol, nanomotors and nanorockers.</a> Optics Express. 10 (19), 984-989 (2002).</li><li>Arita, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rotational+dynamics+and+heating+of+trapped+nanovaterite+particles.">Rotational dynamics and heating of trapped nanovaterite particles.</a> ACS Nano. 10 (12), 11505-11510 (2016).</li><li>Lee, Y. E., Fung, K. H., Jin, D., Fang, N. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+torque+from+enhanced+scattering+by+multipolar+plasmonic+resonance.">Optical torque from enhanced scattering by multipolar plasmonic resonance.</a> Nanophotonics. 3 (6), 343-350 (2014).</li><li>Kyrsting, A., Bendix, P. M., Stamou, D. G., Oddershede, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heat+profiling+of+three-dimensionally+optically+trapped+gold+nanoparticles+using+vesicle+cargo+release.">Heat profiling of three-dimensionally optically trapped gold nanoparticles using vesicle cargo release.</a> Nano Letters. 11 (2), 888-892 (2010).</li><li>Andres-Arroyo, A., Wang, F., Toe, W. J., Reece, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrinsic+heating+in+optically+trapped+au+nanoparticles+measured+by+dark-field+spectroscopy.">Intrinsic heating in optically trapped au nanoparticles measured by dark-field spectroscopy.</a> Biomedical Optics Express. 6 (9), 3646-3654 (2015).</li><li>Ye, X., Zheng, C., Chen, J., Gao, Y., Murray, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+binary+surfactant+mixtures+to+simultaneously+improve+the+dimensional+tunability+and+monodispersity+in+the+seeded+growth+of+gold+nanorods.">Using binary surfactant mixtures to simultaneously improve the dimensional tunability and monodispersity in the seeded growth of gold nanorods.</a> Nano Letters. 13 (2), 765-771 (2013).</li><li>Arias-Gonz&#225;lez, J. R., Nieto-Vesperinas, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+forces+on+small+particles:+attractive+and+repulsive+nature+and+plasmon-resonance+conditions.">Optical forces on small particles: attractive and repulsive nature and plasmon-resonance conditions.</a> JOSA A. 20 (7), 1201-1209 (2003).</li><li>Berg-S&#246;rensen, K., Flyvbjerg, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Power+spectrum+analysis+for+optical+tweezers.">Power spectrum analysis for optical tweezers.</a> Review of Scientific Instruments. 75 (3), 594-612 (2004).</li><li>Gittes, F., Schmidt, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interference+model+for+back-focal-plane+displacement+detection+in+optical+tweezers.">Interference model for back-focal-plane displacement detection in optical tweezers.</a> Optics Letters. 23 (1), 7-9 (1998).</li><li>Verre, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metasurfaces+and+colloidal+suspensions+composed+of+3D+chiral+Si+nanoresonators.">Metasurfaces and colloidal suspensions composed of 3D chiral Si nanoresonators.</a> Advanced Materials. 29 (29), (2017).</li><li>Verre, R., Odebo L&#228;nk, N., Andr&#233;n, D., &#352;&#237;pov&#225;, H., K&#228;ll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-scale+fabrication+of+shaped+high+index+dielectric+nanoparticles+on+a+substrate+and+in+solution.">Large-scale fabrication of shaped high index dielectric nanoparticles on a substrate and in solution.</a> Advanced Optical Materials. , (2018).</li></ol>

作者没有什么可透露的。

本协议中描述的光阱设置是围绕一个商业倒置显微镜建立的, 使用红色激光光。然而, 所概述的技术是多才多艺的, 可用于构造圆形偏振光镊围绕大多数商业或家庭制造的显微镜, 无论是直立和倒置, 只有轻微的变化。只要光学元件和探测器的其余部分在这个特定的波长下工作, 就可以在宽可见近红外光谱中选择俘获激光波长。然而, 在选择激光波长时, 应考虑要操作的粒子共振的大小和光谱附近, 因为这将影响到光俘获力和旋转性能2,5,光热效应的大小1, 并且陷印稳定性26。我们以前成功地使用了660、785、830和1064纳米激光波长的圆极化激光镊子。
光阱设置的一个最重要的组成部分是显微镜的目标。该协议的目标是一个干目标与 NA = 0.95。对干燥目标的用途在实验上更加简单地实现设置;然而, 由于样品细胞界面的折射导致光学畸变。在目前的情况下, 结果是一个稍微扩大的焦点点 (~ 1.2 µm) 相比, 衍射极限 (~ 0.4 µm), 但这并不显著改变的一般或旋转性能的平台。在主, 可以使用广泛的显微镜目标, 只要他们有良好的传播在捕获波长, 良好的极化维护和足够长的工作距离, 以执行捕获通过显微镜覆盖滑移和层的水。在2D 陷印的情况下, NA 可能相对较低, 这使得整个实验更加简单, 并在焦点上提供了更干净的圆极化。然而, 比起高 NA 目标, 可能需要更高的激光功率。在我们的经验中, 捕获、旋转和暗场光谱的最佳性能是以 NA 0.7-0.95 的目标获得的, 但是可以使用较低和更高的 na 目标。
为了获得良好的旋转运动光子相关测量, 需要一个快速的单像素检测器。选择一个至少有两个带宽的探测器, 最好是十倍, 比预期的旋转频率高乘以形状简并系数和高灵敏度在使用的陷波波长。放大 Si 探测器, 单光子计数 APDs, 和并联机床已成功地用于不同的设置在我们的实验室。其他信息, 例如陷阱刚度, 可以通过测量和分析粒子平移位移使用已建立良好的技术, 如功率谱分析5。以前的一些出版物描述了这项技术38、39的不同变体。DF 光谱学可以使用广泛的自由空间或光纤耦合光谱仪进行, 选择应该基于光谱范围和波长和时间分辨率所需的计划研究。
当执行补漏白实验时, 附加粒子可能会意外进入陷阱。这可以通过监视旋转频率来检测, 因为扰动会强烈地波动。通过 DF 显微镜进行目视检查可以验证是否存在附加粒子, 在这种情况下, 可以移动舞台以避免进一步的干扰, 或者需要重新启动实验。
所述系统是实现金属纳米粒子2D 约束和旋转的一种简单有效的方法。但是, 对于某些应用程序来说, 3D 补漏白所带来的额外的操作自由度很重要, 因此当前的配置是一个限制。然而, 3D 限制和旋转可能是可以实现的, 利用计数器传播激光镊子或更奇异的陷阱配置。
虽然这里讨论的粒子和系统参数可以优化, 以减少光热加热到低于 15 K4, 与金属纳米粒子的等离子激发相关的温度增加可能会有问题, 在某些应用。一个可能的途径进一步减少热量是使用高指数的介电纳米粒子, 而不是等离子粒子。这种粒子支持强的 Mie 型散射共振, 但同时表现出较低的固有吸收系数。我们最近已经能够制造胶体共振硅纳米粒子, 这在这方面可能证明是有用的40,41。

本文介绍的方法复制了我们以前工作1中使用的那些用于研究影响轻型金纳米旋转马达的纳米光热效应。实验平台的变体已用于若干相关出版物2、3、4、5、6、7、8、9。
光镊广泛应用于物理、生物学、工程10、11、12、13、14 的小长度尺度上的位置、力和线性动量传递的控制..圆偏振光携带的角动量可用于附加运动控制, 因为它不断地向被困物体传递扭矩15。通过将光线性和角动量的传递结合在一起, 就可以构建具有不同应用潜力的无创旋转 nanomotors, 如将药物交付到单细胞16、17、纳米尺度手术18, 活跃 nanofluidics19, 其中之一。
利用金属纳米粒子作为光驱动操作的主体, 可以利用局部表面等离子体共振 (LSPR) 的优点, 提供较大的光学剖面, 对环境变化的灵敏度高, 且具有较大的场增强功能20、21、22、23。这导致了大量的研究在边界之间的 plasmonics 和光操作8,24,25,26,27。LSPR 提供的强光物质相互作用使我们能够设计一个平台, 在这里, 圆极化激光镊子能够驱动金纳米棒在水2的记录旋转频率下旋转。通过跟踪旋转纳米的布朗运动, 可以获得3、5的有关其环境和温度的详细信息。同时, 光谱分析为分析1旋转纳米的局部温度和形态稳定性提供了一个额外的独立的信息通道。一系列的系统和配置已被用于研究和应用在光学镊子的旋转运动, 产生重要的洞察力在领域15,28,29,30,31,32. 然而, 大多数研究都处理了直径为几微米的物体, 而一个单一的纳米可以进入纳米尺寸的体系。此外, 当金纳米棒作为旋转 nanomotor, 扭矩是有效转移主要通过散射2,33。这降低了被困粒子3、34、35过热的风险。
在下面的方法中, 我们概述了建立一个能够有效地捕捉和旋转金属纳米粒子的系统所需的步骤。这些研究中所考虑的金纳米棒具有较高的散射截面, 辐射压力在传播方向上比抗梯度力强。为了仍然限制粒子在 3D, 我们利用的力量平衡之间的库仑排斥从玻璃表面和激光散射力的传播方向。这2维陷印配置大大扩大了捕获粒子的范围, 与标准的3D 光镊相比, 它可以很容易地结合暗场光学成像和光谱学。
一个被困和旋转的金属纳米粒子与它的环境相互作用, 而关于这种相互影响的详细信息包含在它的运动和光谱性质中。在阐述了如何构造圆极化光镊之后, 本文还概述了在实验装置中如何集成探测旋转动力学和测量瑞利散射谱的仪器。其结果是一个多功能的平台, 研究纳米旋转现象的物理, 化学和生物学。
该协议假设研究员可以获得合适的胶体金属纳米粒子, 最好是单晶金纳米棒。金纳米棒可以从专业公司购买, 或者用湿化学方法在室内合成。我们实验中使用的纳米棒是由种子介导的生长方法在叶等中描述的。201336。这是有利的, 如果纳米粒子的形貌和光学性能良好的特点, 例如使用扫描电子显微镜 (SEM) 和光学消光测量。图 1显示了从这些测量中记录的用于代表性纳米类型1的数据。
该协议的概述如下: 第一部分介绍了基于圆极化的光镊的构造。在第二部分中, 我们描述了如何通过记录 nanomotor 的旋转动力学和散射特性来提取信息。利用光子相关谱技术, 通过在快速单像素探测器3上通过线性偏振器对散射激光进行滤波, 测量捕获粒子的旋转频率和旋转布朗运动。通过将数据拟合为理论自相关函数, 可以提取2、3旋转布朗扩散的自转频率和衰减时间。利用暗场光谱法测量了被困和旋转纳米粒子的光学特性, 为粒子及其环境提供了互补信息。在第三节中, 我们描述了金纳米棒的捕获和旋转的实验过程。
该协议所描述的这一点是一个简单的路径, 一个功能循环偏振光光镊系统的纳米粒子旋转。然而, 有时出现的问题需要更多的关注。在第四节中, 我们概述了我们遇到的一些常见问题以及如何处理这些问题。其中包括与纳米粒子光学特性有关的问题, 导致陷阱稳定性较差 (4.1), 由于 beamsplitter 双折射 (4.2) 引起的次优圆极化而导致的低旋转频率, 在玻璃表面粘附纳米粒子由于库仑斥力不足 (4.3), 偏离自特征自相关信号 (4.4)。

<table><tbody><tr><td>Gold nanoparticles</td><td></td><td></td><td>Purchased or home-grown</td></tr><tr><td>Commersial inverted microscope</td><td>Nikon</td><td>Eclipse TI</td><td></td></tr><tr><td>Trapping laser</td><td>Cobolt</td><td>Flamenco 05-01&amp;nbsp;</td><td>660 nm</td></tr><tr><td>Objective</td><td>Nikon</td><td>CFI Plan Apo Lambda 40X</td><td></td></tr><tr><td>Laser safety googles</td><td>Thorlabs</td><td>LG4</td><td></td></tr><tr><td>Assorted optomechanical components for mounting optics.</td><td></td><td></td><td>A range of mounts, posts and components from any company</td></tr><tr><td>Lens 1 Keplarian telescope</td><td>Thorlabs</td><td>AC254-035-A-ML</td><td></td></tr><tr><td>Lens 2 Keplarian telescope</td><td>Thorlabs</td><td>LA1725-A-ML</td><td></td></tr><tr><td>Silver coated mirrors</td><td>Thorlabs</td><td>PF10-03-P01</td><td></td></tr><tr><td>Kinematic mirror mounts</td><td>Thorlabs</td><td>KM100</td><td></td></tr><tr><td>Translation stage</td><td>Thorlabs</td><td>PT1/M</td><td>Quantity: 2</td></tr><tr><td>50/50 R/T Beamsplitter</td><td>Chroma</td><td>21000</td><td></td></tr><tr><td>CMOS camera</td><td>Andor</td><td>Zyla 5.5</td><td></td></tr><tr><td>Quarter waveplate (QWP, &amp;lambda;/4)</td><td>Thorlabs</td><td>AQWP05M-600</td><td></td></tr><tr><td>Power meter</td><td>Thorlabs</td><td>PM100USB</td><td></td></tr><tr><td>Photodiode Power Sensors</td><td>Thorlabs</td><td>S121C</td><td></td></tr><tr><td>Linear polarizer</td><td>Thorlabs</td><td>LPVIS050</td><td>For laser polarization measurement</td></tr><tr><td>360&amp;deg; rotation mount</td><td>Thorlabs</td><td>RSP1/M</td><td></td></tr><tr><td>Half waveplate (HWP, &amp;lambda;/2)</td><td>Thorlabs</td><td>AHWP05M-600</td><td>Used if polarization is not sufficient with only QWP</td></tr><tr><td>Oil DF condenser</td><td>Nikon</td><td>C-DO Dark Field Condenser Oil&amp;nbsp;</td><td></td></tr><tr><td>30/70 R/T Beamsplitter</td><td>Chroma</td><td>21009</td><td></td></tr><tr><td>Fast Si detector</td><td>Thorlabs</td><td>PDA36A-EC</td><td></td></tr><tr><td>Data Acquisition Module</td><td>National Instruments</td><td>USB-6361</td><td></td></tr><tr><td>Fiber 400 &amp;micro;m core size</td><td>Thorlabs</td><td>M74L01</td><td></td></tr><tr><td>xy-translation mount</td><td>Thorlabs</td><td>LM1XY/M</td><td></td></tr><tr><td>Linear polarizer</td><td>Thorlabs</td><td>LPVIS050</td><td></td></tr><tr><td>Spectrometer</td><td>Princeton Instruments&amp;nbsp;</td><td>IsoPlane SCT320&amp;nbsp;</td><td></td></tr><tr><td>CCD camera for spectrometer</td><td>Princeton Instruments&amp;nbsp;</td><td>PyLoN&amp;nbsp;</td><td></td></tr><tr><td>Notch filter</td><td>Semrock</td><td>NF03-658E-25</td><td></td></tr><tr><td>Notch filter</td><td>Thorlabs</td><td>NF658-26</td><td></td></tr><tr><td>Ultrasonic cleaner bath</td><td>Branson</td><td>Branson 3510&amp;nbsp;</td><td></td></tr><tr><td>Microscope slide</td><td>Ted Pella</td><td>260202</td><td></td></tr><tr><td>No. 1.5 Coverslips</td><td>VWR</td><td>630-2873</td><td></td></tr><tr><td>Aceton</td><td></td><td></td><td></td></tr><tr><td>Isopropanol</td><td></td><td></td><td></td></tr><tr><td>Basic detergent</td><td>Hellma</td><td>Hellmanex III</td><td>Cleaning if particle sticking is an issue</td></tr><tr><td>Secure-Seal Spacer</td><td>Thermo Fisher</td><td>S24735</td><td>Spacer tape with hole, for making sample cell</td></tr><tr><td>Immersion Oil</td><td>Zeiss</td><td>444960-0000-000&amp;nbsp;</td><td></td></tr><tr><td>PS beads</td><td>Microparticles GmbH</td><td>PS-R-5.0</td><td></td></tr><tr><td>Spectrophotometer</td><td>Agilent</td><td>Cary 5000 UV-Vis-NIR</td><td></td></tr><tr><td>SEM</td><td>Zeiss</td><td>Ultra 55 FEG SEM</td><td></td></tr><tr><td>Tweezers</td><td></td><td></td><td>Any brand</td></tr></tbody></table>

construction and operation of a light-driven gold nanorod rotary motor system

在纳米尺度上产生和测量旋转和扭矩的可能性对生物和人工 nanomotors 的研究和应用具有根本的意义, 可以为单细胞分析提供新的途径, 不平衡的研究纳米系统的热力学和机械驱动。一种简便的驱动旋转方法是在光镊中使用聚焦圆极化激光。利用这种方法, 金属纳米粒子可以作为高效的散射驱动旋转马达, 以前所未有的旋转频率在水中旋转。
在本协议中, 我们概述了纳米粒子旋转用圆极化光镊的构造和操作, 并描述了记录被困粒子的布朗动力学和瑞利散射所需的仪器。旋转运动和散射谱提供了有关纳米微粒及其直接环境的独立信息。实验平台已证明是有用的, 作为一个纳米的粘度和局部温度, 跟踪纳米棒和分子涂层的形态学变化, 并作为一个传感器和探头的光热和热力学过程。

用单像素探测器记录光散射强度波动 (图 3a), 可以探测到圆极化激光镊子中正确捕获的金纳米的旋转和旋转布朗运动。该信号的自相关谱包含振荡分量, 类似于图 3b所示。它可以适合于理论自相关函数。拟合允许提取旋转频率和自相关衰减时间, 这与纳米的旋转布朗波动有关。
正如《议定书》 (指令 4.4.2) 所提到的, 必须使用足够厚的光纤内核来收集光子相关光谱学的背散射激光。如果不是这种情况, 相关函数中将存在与探针体积的粒子平移有关的附加衰变术语, 请参见图 4。通过仔细分析, 可以提供有关系统的更多信息;然而, 它使数据中所包含的旋转布朗动力学的分析复杂化。
为了从捕获的纳米粒子中获得正确的 DF 散射光谱, 如第3.5 节所述, 原始光谱数据需要校准。这是通过记录照明灯频谱以及背景光谱 (图 5a) 来完成的。当聚焦在玻璃表面的强激光, 如纳米棒被困在基体上时, 可能产生一些荧光 (参见图 5a背景光谱中的红色光谱贡献)。这种荧光污染可以减少使用熔融二氧化硅基板。然而, 它是强烈建议记录一个背景频谱与空光镊在正确的激光功率。在记录散射谱的同时, 所有与实际纳米粒子散射无关的光谱分量都得到了补偿, 可以用双洛伦兹拟合函数来拟合光谱, 以提取相关的信息。LSPR 峰值位置 (图 5b)。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57947/57947fig1.jpg"> 图 1: 两个代表性纳米颗粒的 SEM 图像和集合消光谱. a)刻度条为 200 nm。b)蓝色/红色边框的 SEM 图像在 a) 对应的红/蓝光谱, 分别。与横向和纵向 LSPRs 相关的谱峰明显区分。<a href="https://www.jove.com/files/ftp_upload/57947/57947fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57947/57947fig2.jpg"> 图 2: 纳米粒子旋转测量用光镊设置示意图.激光是准直的, 通过 Keplerian 望远镜扩展, 随后通过使用两个可移动的镜子 (M1、M2) 和 beamsplitter (BS) 来引导目标。激光路径中的两个 waveplates 优化光镊的圆极化 (λ/2, λ/4)。在光子相关光谱学和旋转动力学测量的线性偏光片后, 可以收集背散射激光。除去激光光后, 散射白光被引导到光谱仪或照相机。<a href="https://www.jove.com/files/ftp_upload/57947/57947fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57947/57947fig3.jpg"> 图 3: 具有自适应和旋转纳米的曲线拟合的代表性强度和相关数据. a)在1s 的线性偏振器后, 单像素探测器记录的强度波动, 并在波动的剧情中放大。b)自相关从背散射激光中收集的旋转金纳米 (蓝点) 的强度波动数据。数据显示了几个周期后衰减的振荡。振荡与纳米的旋转频率有关, 而衰变则是由旋转布朗运动引起的。对理论自相关函数进行了拟合 (红线) 提取f = 24285 45 Hz 的旋转频率和τ0 = 40.9 @ 1.06 µs 的相关衰减时间。f和τ0不确定度代表95% 置信区间的配合, 其中有一个确定系数 (R2) 的0.9877。<a href="https://www.jove.com/files/ftp_upload/57947/57947fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57947/57947fig4.jpg"> 图 4: 光子相关光谱学测量中探针体积过小的问题.旋转金纳米的自相关数据, 使用厚 (400 µm, 蓝色数据) 和薄 (62.5 µm, 红色数据) 光纤收集。收集使用厚纤维确保纳米始终局限在探头体积内, 而自相关函数仅测量旋转动力学。当探头体积不足时, 由于平移布朗运动而出现额外的衰减项。在b)和c)中, 显示了背面照明收集区的效果和图像的示意图。刻度条为2µm.<a href="https://www.jove.com/files/ftp_upload/57947/57947fig4large.jpg" target="_blank">请点击这里查看这个数字的大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57947/57947fig5.jpg"> 图 5: 为被 660 nm 激光光所捕获的金色纳米所记录的典范的暗场散射光谱.光谱区域630-670 毫微米 (1.85-1. 97 eV) 被歪曲由于陷波器需要阻挡陷印激光光。a)原始散射光谱 (深蓝色), 显示不属于粒子散射的固有特征, 应该校准。这些包括背景光谱 (红色), 其中包含由高度聚焦的激光激发的自发荧光, 和白色光励磁光谱 (橙色, 记录没有凹槽过滤器)。校准后, 校正后的散射光谱 (浅蓝色) 显示两个不同的 LSPR 峰。箭头指示每个频谱的刻度。b)被困的纳米 (蓝点) 的散射光谱, 与洛伦兹模型功能 (红色) 配合使用, 其组件 (浅蓝色和橙色)。在拟合数据时, 不考虑畸变谱区, 拟合的R2为0.9975。<a href="https://www.jove.com/files/ftp_upload/57947/57947fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System at JoVE.com

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

等离子金纳米棒可以被困在液体和旋转的赫频率使用圆极化光镊。介绍用于布朗动力学分析和光 scatteringspectroscopy 的工具, 导致了在许多科学领域中研究和应用的强大系统。

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 ...

construction-operation-light-driven-gold-nanorod-rotary-motor

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Unit 1

Moment of Inertia

Rotation and Rigid Bodies

SCIENTISTS IN ACTION

8.8K 次观看.  Chalmers University of Technology. 等离子金纳米棒可以被困在液体和旋转的赫频率使用圆极化光镊。介绍用于布朗动力学分析和光 scatteringspectroscopy 的工具, 导致了在许多科学领域中研究和应用的强大系统。

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

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 ...

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工程学

Preparation of ZnO Nanorod/Graphene/ZnO Nanorod Epitaxial Double Heterostructure for Piezoelectrical Nanogenerator by Using Preheating Hydrothermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we describe a one-step fabrication technique to synthesis freestanding ZnO nanorod/graphene/ZnO nanorod double heterostructure. The preparation of the double heterostructure is performed by using thermal chemical vapor deposition (CVD) and preheating hydrothermal technique. In addition, the morphological properties were characterized by using the scanning electron microscopy (SEM). The utility of freestanding double heterostructure is demonstrated by fabricating the piezoelectric nanogenerator. The electrical output is improved up to 200% compared to that of a single heterostructure owing to the coupling effect of the piezoelectricity between the arrays of ZnO nanorods on the top and bottom of graphene. This unique double heterostructure have a tremendous potential for applications of electrical and optoelectrical devices where the high number density and specific surface area of nanorod are needed, such as pressure sensor, immuno-biosensor and dye-sensitized solar cells.

One-step fabrication method for obtaining freestanding epitaxial double heterostructure is presented. This approach could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure, leading to a piezoelectric nanogenerator with an increased output electrical performance.

利用预热水热氧化锌纳米棒/石墨烯/氧化锌纳米棒外延双异质结的机压电纳米发电机的研制

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we ...

Design and Assembly of an Ultra-light Motorized Microdrive for Chronic Neural Recordings in Small Animals

The ability to chronically record from populations of neurons in freely behaving animals has proven an invaluable tool for dissecting the function of neural circuits underlying a variety of natural behaviors, including navigation1 , decision making 2,3, and the generation of complex motor sequences4,5,6. Advances in precision machining has allowed for the fabrication of light-weight devices suitable for chronic recordings in small animals, such as mice and songbirds. The ability to adjust the electrode position with small remotely controlled motors has further increased the recording yield in various behavioral contexts by reducing animal handling.6,7
 Here we describe a protocol to build an ultra-light motorized microdrive for long-term chronic recordings in small animals. Our design evolved from an earlier published version7, and has been adapted for ease-of use and cost-effectiveness to be more practical and accessible to a wide array of researchers. This proven design 8,9,10,11 allows for fine, remote positioning of electrodes over a range of ~ 5 mm and weighs less than 750 mg when fully assembled. We present the complete protocol for how to build and assemble these drives, including 3D CAD drawings for all custom microdrive components.

The design, fabrication and assembly of an ultra-light motorized microdrive is described. The device provides a cost-effective and easy-to-use solution for chronic recordings of single units in small behaving animals.

设计和组装的超轻型电动微型硬盘（Microdrive）慢性神经录音的小动物

The ability to chronically record from populations of neurons in freely behaving animals has proven an invaluable tool for dissecting the function of ...

神经科学

Production of Dynein and Kinesin Motor Ensembles on DNA Origami Nanostructures for Single Molecule Observation

Cytoskeletal motors are responsible for a wide variety of functions in eukaryotic cells, including mitosis, cargo transport, cellular motility, and others. Many of these functions require motors to operate in ensembles. Despite a wealth of knowledge about the mechanisms of individual cytoskeletal motors, comparatively less is known about the mechanisms and emergent behaviors of motor ensembles, examples of which include changes to ensemble processivity and velocity with changing motor number, location, and configuration. Structural DNA nanotechnology, and the specific technique of DNA origami, enables the molecular construction of well-defined architectures of motor ensembles. The shape of cargo structures as well as the type, number and placement of motors on the structure can all be controlled. Here, we provide detailed protocols for producing these ensembles and observing them using total internal reflection fluorescence microscopy. Although these techniques have been specifically applied for cytoskeletal motors, the methods are generalizable to other proteins that assemble in complexes to accomplish their tasks. Overall, the DNA origami method for creating well-defined ensembles of motor proteins provides a powerful tool for dissecting the mechanisms that lead to emergent motile behavior.

The goal of this protocol is to form ensembles of molecular motors on DNA origami nanostructures and observe the ensemble motility using total internal reflection fluorescence microscopy.

生产用于单分子观察的DNA折纸纳米结构的Dynein和Kinesin电机组合

Cytoskeletal motors are responsible for a wide variety of functions in eukaryotic cells, including mitosis, cargo transport, cellular motility, and ...

生物化学

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces are demonstrated. This work requires careful design, considerable synthetic effort, and proper analysis. The rotary motion of the molecular motor in solution is shown by 1H NMR and UV-vis absorption spectroscopy techniques. In addition, the method to graft the motor onto an amine-coated quartz is described. This method helps to gain more insight into molecular machines.

The manuscript describes how to synthesize and graft a molecular motor on surfaces for single molecular imaging.

表面光驱动分子电机的单分子成像

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces ...

化学

Gold Nanorod-assisted Optical Stimulation of Neuronal Cells

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

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

金纳米棒辅助神经细胞的刺激光

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

Rapid, Scalable Assembly and Loading of Bioactive Proteins and Immunostimulants into Diverse Synthetic Nanocarriers Via Flash Nanoprecipitation

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging applications. This increased specificity can have significant clinical implications, including decreased side effects and lower dosages with higher potency. Furthermore, the in situ targeting and controlled modulation of specific cell subsets can enhance in vitro and in vivo investigations of basic biological phenomena and probe cell function. Unfortunately, the required expertise in nanoscale science, chemistry and engineering often prohibit laboratories without experience in these fields from fabricating and customizing nanomaterials as tools for their investigations or vehicles for their therapeutic strategies. Here, we provide protocols for the synthesis and scalable assembly of a versatile non-toxic block copolymer system amenable to the facile formation and loading of nanoscale vehicles for biomedical applications. Flash nanoprecipitation is presented as a methodology for rapid fabrication of diverse nanocarriers from poly(ethylene glycol)-bl-poly(propylene sulfide) copolymers. These protocols will allow laboratories with a wide range of expertise and resources to easily and reproducibly fabricate advanced nanocarrier delivery systems for their applications. The design and construction of an automated instrument that employs a high-speed syringe pump to facilitate the flash nanoprecipitation process and to allow enhanced control over the homogeneity, size, morphology and loading of polymersome nanocarriers is described.

Nanomaterials provide versatile mechanisms of controlled therapeutic delivery for both basic science and translational applications, but their fabrication often requires expertise that is unavailable in most biomedical laboratories. Here, we present protocols for the scalable fabrication and therapeutic loading of diverse self-assembled nanocarriers using flash nanoprecipitation.

快速, 可伸缩的组装和负载的生物活性蛋白和免疫增强剂到不同的合成 Nanocarriers 通过闪光 Nanoprecipitation

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging ...

生物工程

Construction of an Improved Multi-Tetrode Hyperdrive for Large-Scale Neural Recording in Behaving Rats

Monitoring the activity patterns of a large population of neurons over many days in awake animals is a valuable technique in the field of systems neuroscience. One key component of this technique consists of the precise placement of multiple electrodes into desired brain regions and the maintenance of their stability. Here, we describe a protocol for the construction of a 3D-printable hyperdrive, which includes eighteen independently adjustable tetrodes, and is specifically designed for in vivo extracellular neural recording in freely behaving rats. The tetrodes attached to the microdrives can either be individually advanced into multiple brain regions along the track, or can be used to place an array of electrodes into a smaller area. The multiple tetrodes allow for simultaneous examination of action potentials from dozens of individual neurons, as well as local field potentials from populations of neurons in the brain during active behavior. In addition, the design provides for simpler 3D drafting software that can easily be modified for differing experimental needs.

We present the construction of a 3D-printable hyperdrive with eighteen independently adjustable tetrodes. The hyperdrive is designed to record brain activity in freely behaving rats over a period of several weeks.

一种改进的多电子四极超光速引擎在行为大鼠大尺度神经记录中的构建

Monitoring the activity patterns of a large population of neurons over many days in awake animals is a valuable technique in the field of systems ...

Hybrid Microdrive System with Recoverable Opto-Silicon Probe and Tetrode for Dual-Site High Density Recording in Freely Moving Mice

Multi-regional neural recordings can provide crucial information to understanding fine-timescale interactions between multiple brain regions. However, conventional microdrive designs often only allow use of one type of electrode to record from single or multiple regions, limiting the yield of single-unit or depth profile recordings. It also often limits the ability to combine electrode recordings with optogenetic tools to target pathway and/or cell type specific activity. Presented here is a hybrid microdrive array for freely moving mice to optimize yield and a description of its fabrication and reuse of the microdrive array. The current design employs nine tetrodes and one opto-silicon probe implanted in two different brain areas simultaneously in freely moving mice. The tetrodes and the opto-silicon probe are independently adjustable along the dorsoventral axis in the brain to maximize the yield of unit and oscillatory activities. This microdrive array also incorporates a set-up for light, mediating optogenetic manipulation to investigate the regional- or cell type-specific responses and functions of long-range neural circuits. In addition, the opto-silicon probe can be safely recovered and reused after each experiment. Because the microdrive array consists of 3D-printed parts, the design of microdrives can be easily modified to accommodate various settings. First described is the design of the microdrive array and how to attach the optical fiber to a silicon probe for optogenetics experiments, followed by fabrication of the tetrode bundle and implantation of the array into a mouse brain. The recording of local field potentials and unit spiking combined with optogenetic stimulation also demonstrate feasibility of the microdrive array system in freely moving mice.

This protocol describes the construction of a hybrid microdrive array that allows implantation of nine independently adjustable tetrodes and one adjustable opto-silicon probe in two brain regions in freely moving mice. Also demonstrated is a method for safely recovering and reusing the opto-silicon probe for multiple purposes.

混合微驱系统,带可回收的光电探头和Tetrode,用于自由移动小鼠的双位点高密度记录

Multi-regional neural recordings can provide crucial information to understanding fine-timescale interactions between multiple brain regions. However, ...

Biophysical Characterization of Flagellar Motor Functions

The role of flagellar motors in bacterial motility and chemotaxis is well-understood. Recent discoveries suggest that flagellar motors are able to remodel in response to a variety of environmental stimuli and are among the triggers for surface colonization and infections. The precise mechanisms by which motors remodel and promote cellular adaptation likely depend on key motor attributes. The photomultiplier-based bead-tracking technique presented here enables accurate biophysical characterization of motor functions, including adaptations in motor speeds and switch-dynamics. This approach offers the advantage of real-time tracking and the ability to probe motor behavior over extended durations. The protocols discussed can be readily extended to study flagellar motors in a variety of bacterial species.

Recent findings suggest that bacterial flagellar motors sense a variety of environmental signals and remodel in response. The bead-assays discussed here are expected to help explain the role of remodeling in cellular adaptation to environmental stressors.

鞭毛马达功能的生物物理表征

The role of flagellar motors in bacterial motility and chemotaxis is well-understood. Recent discoveries suggest that flagellar motors are able to remodel ...