The financial support by DFG (German research foundation, project CZ 55/30-1) for parts of this work is gratefully acknowledged.

1.组装实验装置<ol><li> 制备的基端侧 <ol><li>放置和固定在激光提供一个准直光束 - 或在光纤的出射面利用具有准直光学器件的光纤耦合激光。 </li><li>把偏振光束分离器（PBS），以将激光束分裂成参考和物体光束。通过在其旋转而旋转的HWP座，直到参考光束和物体光束（在远端侧）的功率大致相同转半波片（HWP）的方向。通过将屏幕分为两个参考和物光束进行检查。选择的PBS的取向，以使参考光束的偏振适合的偏振敏感空间光调制器（SLM）。 </li><li>把一个光束分离器（BS）到参考光束与参考光束分成两束。放置光调制器（OM），使得这两个光束从BS1来可以分别通过OM1和OM2，&lt;/ LI&gt; <li>结合两束传递OM1和OM2在BS2采用两个镜子。调节分束器和反射镜，使得两个光束在空间上分离。 </li><li>仔细对齐BS5，以确保两个光束的入射方向垂直于SLM的像素平面，忽略BS3和BS4在第一。首先，没有显示在SLM上， 也就是说 ，它的作用就像一个镜子直到校准（在整个步骤2）的端部。 </li><li>调整构成为了获得互补金属氧化物半导体（CMOS）相机在SLM平面的锐利图像的开普勒望远镜的位置和两个镜头（L）之间的距离。观看L1和L2的正确方向（平侧面彼此面对），以尽量减少像差。 </li></ol></li><li> 制备的远端侧 <ol><li>使用BS7到物体光束分成两束，并在使用两个反射镜BS8组合它们。再次，调整光束分离器和英里rrors使两个光束在空间上分离。 </li><li>使用BS9它们旨在显微镜物镜（OBJ）偏转两个光束。集中OBJ2的多模光纤（MMF）的前端。通过观察从使用L3和电荷耦合器件（CCD）照相机该MMF背反射检查对焦。 </li></ol></li><li> 连接的近端和远端侧 <ol><li>照准从物光束退出MMF采用OBJ1的光。 </li><li>拆分使用BS6物体光束，首先忽略线性偏振器（LP）。与BS3两个参考光束和BS4采用镜面结合两种对象横梁。调节分束器和反射镜，使得每一对基准和物体光束重叠在SLM，用小角度（小于1度）相交。 </li><li>确保参考的功率和物体光束是通过转动的HWP的方向，根据步骤1.1.2大致相等。 </li><li>检查干扰pattern（离轴全息图）的CMOS摄像头，并相应地调整交叉角。增加角度，直到干涉条纹间距大致等于CMOS摄像头上的两个像素的大小。 </li><li>调整LP的取向物体光束和参考光束的偏振相匹配，以获得在CMOS摄像机图像中的干涉图案的最大对比度，使相机图像显示鲜明条纹。 </li></ol></li></ol> 2.校准系统<ol><li> 校准SLM和CMOS的像素关系 <ol><li>照亮只使用参考光束中的一个的整个SLM并阻断其它参考和对象束。 </li><li>捕获与CMOS照相机SLM的图像。 </li><li>得到SLM的CMOS摄像图像中的使用绘图软件，并在PC上的鼠标光标的左上角， 例如的坐标。使用这些像素坐标原点对于SLM。 </li><li>删除所有光束块。 </li></ol></li><li> 校准信号路径 <ol><li>同时阻断参考光束2和物体光束2。 </li><li>捕获与CMOS照相机全息图的图像。评估采用了棱角分明谱法19记录的全息图的阶段。计算的倒相在梁1的相应区域。 </li><li>卸下前束块，现在都阻挡参考光束1和对象梁1。 </li><li>捕获与CMOS照相机全息图的图像。测量在再次使用角谱方法记录的全息图的相位。计算的倒相在光束2的相应区域。 </li><li>删除所有光束块。 </li></ol></li></ol> 3.传递信号<ol><li>块的对象光束。 </li><li>在梁1和2的相应区域缝合所计算的反转相位图像一起并显示在SLM上整个图像，通常使用的计算机图形端口。 </li><li>通过激活OM1和OM2启动输入信号1和2的调制。 </li><li>观察输出信号1和2中的CCD照相机上。 </li></ol>

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The authors have nothing to disclose.

实验设置（在协议步骤1）的组装需要的光学部件的相对于彼此的透彻对齐。最重要的方面是参考光束到SLM的，以确保高的PBR矩形发病率。 为了提高在设置两个以上的发射的信号，也可使用附加的分束器。作为替代，基于光纤的实施将更为紧凑和坚固允许系统是便携式的用于在生物光子学原位调查。如果单端的访问是可能只，基于模型的校准溶液20</...

多个光信号通过一多模光纤（MMF）的传输是在通信工程1和生物光子学2明显。在通信工程，空间多路复用（SDM）被认为是为了增强对未来的数据传输应用的光纤的传输容量从在有限的空间的利用率更高受益，一个可行的解决方案相比，多个单模光纤3。在生物光子学，生物样品是由透光通过MMF内窥镜4操纵。例如，使用MMF内窥镜单个神经元的独立的光学控制是用于光遗传学兴趣为了研究神经元网络中的大脑5。然而，投射到该MMF输入面的光的传播到outpu期间受到失真由于模式混合和分散MMF的效应的T方面。其结果是，光传播被改变，这使得信号传输有挑战性。 波前成形方法6,7在散射使用空间光调制器（SLM）的媒体应用并启用对失真补偿由于在光传播8飞散。有迹象表明，优化使用光学反馈9输出迭代的方法。这些方法是相当耗时，因为有必要为许多迭代和自由度高的，相应于大量调制器元件。另一种方法是完全确定通过其传输矩阵10描述该MMF内的失真。如果要发送的模式的数目是大的，这将是耗时的，因为良好。与此相反，数字光相位共轭（DOPC）被认为是快速和这里有利的，因为只有少数焦斑有在该MMF的输出面中产生。相位共轭方法也被证明用于聚焦或成像通过生物组织12，13，14。 到目前为止，DOPC被用于一个单一的时间信号仅15，16，并通过一个MMF 17施加的光的传输。多个独立信号A DOPC方法尚未实现。我们已经开发了一种增强的方法DOPC使用提供个人波前整形采用单相仅SLM 18的每个信号多个光信号独立传输。到这个目的，在SLM被分段成区域，每个信号来传送。所提出的实验装置如图1所示，其中校准是在实际传输之前执行在b）中发生的）。 <img alt="图1" src="/files/ftp_upload/55407/55407fig1.jpg" /> 图1：实验装置。 BS =分光镜，CCD =电荷耦合器件，OM =光调制器，CMOS =互补金属氧化物半导体，HWP =半波片，L =透镜，LP =线性偏振器，MMF =多模光纤，OBJ =显微镜物镜， PBS =偏振分束器，SLM =空间光调制器（仅相） -仅适用于（A）的校准和（b）传输相关的横梁被描述<a href="http://ecsource.jove.com/files/ftp_upload/55407/55407fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>spatial light modulator</td>
			<td>Holoeye</td>
			<td>PLUTO&#8208;VIS&#8208;016</td>
			<td></td>
		</tr>
		<tr>
			<td>CMOS camera</td>
			<td>Mikrotron</td>
			<td>MC4082</td>
			<td></td>
		</tr>
		<tr>
			<td>diode&#8208;pumped solid state laser</td>
			<td>Laser Quantum</td>
			<td>torus 532</td>
			<td></td>
		</tr>
		<tr>
			<td>CCD camera</td>
			<td>IDS</td>
			<td>U3&#8208;3482LE&#8208;M</td>
			<td>CMOS camera; suitable as well</td>
		</tr>
		<tr>
			<td>lens 1</td>
			<td>Qioptiq</td>
			<td>G063204000</td>
			<td></td>
		</tr>
		<tr>
			<td>lens 2</td>
			<td>Qioptiq</td>
			<td>G063203000</td>
			<td></td>
		</tr>
		<tr>
			<td>lens 3</td>
			<td>Thorlabs</td>
			<td>AC508&#8208;180&#8208;A&#8208;ML</td>
			<td></td>
		</tr>
		<tr>
			<td>multimode fiber</td>
			<td>Thorlabs</td>
			<td>M14L02</td>
			<td></td>
		</tr>
		<tr>
			<td>beam splitters</td>
			<td>Thorlabs</td>
			<td>BS013</td>
			<td>9x</td>
		</tr>
		<tr>
			<td>polarizing beam splitters</td>
			<td>Thorlabs</td>
			<td>PBS251</td>
			<td></td>
		</tr>
		<tr>
			<td>mirrors</td>
			<td>Thorlabs</td>
			<td>PF10&#8208;03&#8208;P01</td>
			<td>5x</td>
		</tr>
		<tr>
			<td>microscope objectives</td>
			<td>Thorlabs</td>
			<td>RMS20X</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>half wave plates</td>
			<td>Thorlabs</td>
			<td>WPH10M&#8208;532</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>linear polarizer</td>
			<td>Thorlabs</td>
			<td>LPVISB050&#8208;MP2</td>
			<td></td>
		</tr>
		<tr>
			<td>optical modulators</td>
			<td>Thorlabs</td>
			<td>MC2000B&#8208;EC</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>linear and rotation stage for CMOS camera</td>
			<td>Thorlabs</td>
			<td>XYR1/M</td>
			<td></td>
		</tr>
		<tr>
			<td>fiber connector</td>
			<td>Thorlabs</td>
			<td>S120&#8208;SMA</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>reducing ring for microscope objectives</td>
			<td>Qioptiq</td>
			<td>G061621000</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>xy adjustment for objective adapters</td>
			<td>Qioptiq</td>
			<td>G061025000</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>z translation mount for fiber adapter</td>
			<td>Thorlabs</td>
			<td>SM1Z</td>
			<td>2x</td>
		</tr>
		<tr>
			<td>rods for fiber alignment to objectives</td>
			<td>Qioptiq</td>
			<td>G061210000</td>
			<td>8x</td>
		</tr>
		<tr>
			<td>mounts for lenses 1 and 2 plus two phantom mounts</td>
			<td>Qioptiq</td>
			<td>G061047000</td>
			<td>4x</td>
		</tr>
		<tr>
			<td>rail carriers for objective and lens mounts</td>
			<td>Qioptiq</td>
			<td>G061372000</td>
			<td>6x</td>
		</tr>
		<tr>
			<td>rail for rail carriers</td>
			<td>Qioptiq</td>
			<td>G061359000</td>
			<td>2x</td>
		</tr>
		<tr>
			<td colspan="2">adapter for CCD camera to 1 post</td>
			<td></td>
			<td>in-house</td>
		</tr>
		<tr>
			<td>adapter for laser to 4 posts</td>
			<td></td>
			<td></td>
			<td>in-house</td>
		</tr>
		<tr>
			<td>mount for lens 3</td>
			<td>Thorlabs</td>
			<td>LMR2/M</td>
			<td></td>
		</tr>
		<tr>
			<td>mounts for half wave plates</td>
			<td>Thorlabs</td>
			<td>RSP1D/M</td>
			<td>2</td>
		</tr>
		<tr>
			<td>mounts for mirrors</td>
			<td>Thorlabs</td>
			<td>KM100</td>
			<td>5x</td>
		</tr>
		<tr>
			<td>mount for linear polarizer</td>
			<td>Thorlabs</td>
			<td>RSP05/M</td>
			<td></td>
		</tr>
		<tr>
			<td>mounts for beam splitters and SLM</td>
			<td>Thorlabs</td>
			<td>KM100PM/M</td>
			<td>11x</td>
		</tr>
		<tr>
			<td>clamping arms for beam splitters and SLM</td>
			<td>Thorlabs</td>
			<td>PM4/M</td>
			<td>11x</td>
		</tr>
		<tr>
			<td>posts for mounts, rail carriers and adapters</td>
			<td>Thorlabs</td>
			<td>TR75/M</td>
			<td>29x</td>
		</tr>
		<tr>
			<td>holders for posts</td>
			<td>Thorlabs</td>
			<td>PH50/M</td>
			<td>29x</td>
		</tr>
		<tr>
			<td>pedestals for holders</td>
			<td>Thorlabs</td>
			<td>BE1/M</td>
			<td>29x</td>
		</tr>
		<tr>
			<td>clamping forks for pedestals</td>
			<td>Thorlabs</td>
			<td>CF125</td>
			<td>29x</td>
		</tr>
	</tbody>
</table>

transmission of multiple signals through an optical fiber using wavefront shaping

多个独立的光信号通过一个多模光纤传输用波前整形，以便在光纤内的传播过程中的光失真进行补偿来实现。我们的方法是基于采用仅单个空间光调制器，其中，所述光学波前单独的调制器的不同区域进行调制，每个光信号的一个区域的数字光学相位共轭。数字光学相位共轭的方法都被认为是比其他波前成形方法，其中（例如）进行光纤的波传播行为的完整判定更快。与此相反，所提出的方法是时有效，因为它仅需要每个光信号的一个校准。该方法可能是适合于通信工程空分复用。进一步的应用领域是生物光子学内镜光传输，特别是在邻ptogenetics，其中单细胞生物组织有以高空间和时间分辨率被选择性地照明。

<html>在2米长的光纤的前端侧的典型输出信号在图2中被描绘。需要注意的是所希望的焦斑（峰值）是伴随着不期望的斑点图案（背景），这是由于DOPC的缺陷作为一个原则问题。相应峰 - 背景比（PBR）等于53（仅信号1是“开”），36分别（只信号2“上”）和20（两个信号1和2“上”）这里， 。用于：（1710目前）时，它支持的模式的较大数量的纤维将PBR可以增加?...

Watch this Scientific Journal Video about Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping at JoVE.com

Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

We demonstrate the transmission of multiple independent signals through a multimode fiber using wavefront shaping employing a single spatial light modulator. By modulating the wavefront for each signal individually, spatially separated foci are transmitted. Potential applications are multiplexed data transfer in communications engineering and endoscopic light delivery in biophotonics.

通过光纤使用波前整形多个信号的传输

The transmission of multiple independent optical signals through a multimode fiber is accomplished using wavefront shaping in order to compensate for the ...

transmission-multiple-signals-through-an-optical-fiber-using

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9.8K 次观看.  TU Dresden. We demonstrate the transmission of multiple independent signals through a multimode fiber using wavefront shaping employing a single spatial light modulator. By modulating the wavefront for each signal individually, spatially separated foci are transmitted. Potential applications are multiplexed data transfer in communications engineering and endoscopic light delivery in biophotonics.

视频: Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

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 ...

科研

生物工程

Attaching Biological Probes to Silica Optical Biosensors Using Silane Coupling Agents

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) technique), make use of various surface modification techniques, that can, for example, prevent surface fouling, tune the hydrophobicity / hydrophilicity of the surface, adapt to a variety of electronic environments, and most frequently, induce specificity towards a target of interest.1-5 These techniques extend the functionality of otherwise highly sensitive biosensors to real-world applications in complex environments, such as blood, urine, and wastewater analysis.2,6-7 While commercial biosensing platforms, such as Biacore, have well-understood, standard techniques for performing such surface modifications, these techniques have not been translated in a standardized fashion to other label-free biosensing platforms, such as Whispering Gallery Mode (WGM) optical resonators.8-9
WGM optical resonators represent a promising technology for performing label-free detection of a wide variety of species at ultra-low concentrations.6,10-12 The high sensitivity of these platforms is a result of their unique geometric optics: WGM optical resonators confine circulating light at specific, integral resonance frequencies.13 Like the SPR platforms, the optical field is not totally confined to the sensor device, but evanesces; this "evanescent tail" can then interact with species in the surrounding environment. This interaction causes the effective refractive index of the optical field to change, resulting in a slight, but detectable, shift in the resonance frequency of the device. Because the optical field circulates, it can interact many times with the environment, resulting in an inherent amplification of the signal, and very high sensitivities to minor changes in the environment.2,14-15
To perform targeted detection in complex environments, these platforms must be paired with a probe molecule (usually one half of a binding pair, e.g. antibodies / antigens) through surface modification.2 Although WGM optical resonators can be fabricated in several geometries from a variety of material systems, the silica microsphere is the most common. These microspheres are generally fabricated on the end of an optical fiber, which provides a "stem" by which the microspheres can be handled during functionalization and detection experiments. Silica surface chemistries may be applied to attach probe molecules to their surfaces; however, traditional techniques generated for planar substrates are often not adequate for these three-dimensional structures, as any changes to the surface of the microspheres (dust, contamination, surface defects, and uneven coatings) can have severe, negative consequences on their detection capabilities. Here, we demonstrate a facile approach for the surface functionalization of silica microsphere WGM optical resonators using silane coupling agents to bridge the inorganic surface and the biological environment, by attaching biotin to the silica surface.8,16 Although we use silica microsphere WGM resonators as the sensor system in this report, the protocols are general and can be used to functionalize the surface of any silica device with biotin.

Biosensors interface with complex, biological environments and perform targeted detection by combining highly sensitive sensors with highly specific probes attached to the sensor via surface modification. Here, we demonstrate the surface functionalization of silica optical sensors with biotin using silane coupling agents to bridge the sensor and the biological environment.

将生物探针使用硅烷偶联剂的硅光学生物传感器

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) ...

Induction of Adhesion-dependent Signals Using Low-intensity Ultrasound

In multicellular organisms, cell behavior is dictated by interactions with the extracellular matrix. Consequences of matrix-engagement range from regulation of cell migration and proliferation, to secretion and even differentiation. The signals underlying each of these complex processes arise from the molecular interactions of extracellular matrix receptors on the surface of the cell. Integrins are the prototypic receptors and provide a mechanical link between extracellular matrix and the cytoskeleton, as well as initiating some of the adhesion-dependent signaling cascades. However, it is becoming increasingly apparent that additional transmembrane receptors function alongside the integrins to regulate both the integrin itself and signals downstream. The most elegant of these examples is the transmembrane proteoglycan, syndecan-4, which cooperates with &alpha;5&beta;1-integrin during adhesion to fibronectin. In vivo models demonstrate the importance of syndecan-4 signaling, as syndecan-4-knockout mice exhibit healing retardation due to inefficient fibroblast migration1,2. In wild-type animals, migration of fibroblasts toward a wound is triggered by the appearance of fibronectin that leaks from damaged capillaries and is deposited by macrophages in injured tissue. Therefore there is great interest in discovering strategies that enhance fibronectin-dependent signaling and could accelerate repair processes.
The integrin-mediated and syndecan-4-mediated components of fibronectin-dependent signaling can be separated by stimulating cells with recombinant fibronectin fragments. Although integrin engagement is essential for cell adhesion, certain fibronectin-dependent signals are regulated by syndecan-4. Syndecan-4 activates the Rac1 protrusive signal3, causes integrin redistribution1, triggers recruitment of cytoskeletal molecules, such as vinculin, to focal adhesions4, and thereby induces directional migration3. We have looked for alternative strategies for activating such signals and found that low-intensity pulsed ultrasound (LIPUS) can mimic the effects of syndecan-4 engagement5. In this protocol we describe the method by which 30 mW/cm2, 1.5 MHz ultrasound, pulsed at 1 kHz (Fig. 1) can be applied to fibroblasts in culture (Fig. 2) to induce Rac1 activation and focal adhesion formation. Ultrasound stimulation is applied for a maximum of 20 minutes, as this combination of parameters has been found to be most efficacious for acceleration of clinical fracture repair6. The method uses recombinant fibronectin fragments to engage &alpha;5&beta;1-integrin, without engagement of syndecan-4, and requires inhibition of protein synthesis by cycloheximide to block deposition of additional matrix by the fibroblasts., The positive effect of ultrasound on repair mechanisms is well documented7,8, and by understanding the molecular effect of ultrasound in culture we should be able to refine the therapeutic technique to improve clinical outcomes.

This protocol describes the stimulation of cultured fibroblasts with low-intensity pulsed ultrasound, which drives focal adhesion formation and Rac1 activation by mimicking engagement of the transmembrane matrix receptor, syndecan-4. This approach allows investigation of a successful clinical technique at the cellular level, thereby providing opportunities for refinement of the therapy.

诱导粘附依赖使用低强度超声波信号

In multicellular organisms, cell behavior is dictated by interactions with the extracellular matrix. Consequences of matrix-engagement range from ...

In vitro Synthesis of Native, Fibrous Long Spacing and Segmental Long Spacing Collagen

Collagen fibrils are present in the extracellular matrix of animal tissue to provide structural scaffolding and mechanical strength. These native collagen fibrils have a characteristic banding periodicity of ~67 nm and are formed in vivo through the hierarchical assembly of Type I collagen monomers, which are 300 nm in length and 1.4 nm in diameter. In vitro, by varying the conditions to which the monomer building blocks are exposed, unique structures ranging in length scales up to 50 microns can be constructed, including not only native type fibrils, but also fibrous long spacing and segmental long spacing collagen. Herein, we present procedures for forming the three different collagen structures from a common commercially available collagen monomer. Using the protocols that we and others have published in the past to make these three types typically lead to mixtures of structures. In particular, unbanded fibrils were commonly found when making native collagen, and native fibrils were often present when making fibrous long spacing collagen. These new procedures have the advantage of producing the desired collagen fibril type almost exclusively. The formation of the desired structures is verified by imaging using an atomic force microscope.

In vitro Synthesis of Native, Fibrous Long Spacing and Segmental Long Spacing Collagen

Simple and reproducible procedures are described for making three structurally distinct collagen assemblies from a common commercially available Type I collagen monomer. Native type, fibrous long spacing or segmental long spacing collagen can be constructed by varying the conditions to which the 300 nm long and 1.4 nm diameter monomer building block is exposed.

在体外合成的原住民，纤维长间距“和”分段长间距胶原蛋白

Collagen fibrils are present in the  extracellular matrix of animal tissue to provide structural scaffolding and  mechanical strength. These native ...

Label-free Single Molecule Detection Using Microtoroid Optical Resonators

Detecting small concentrations of molecules down to the single molecule limit has impact on areas such as early detection of disease, and fundamental studies on the behavior of molecules. Single molecule detection techniques commonly utilize labels such as fluorescent tags or quantum dots, however, labels are not always available, increase cost and complexity, and can perturb the events being studied. Optical resonators have emerged as a promising means to detect single molecules without the use of labels. Currently the smallest particle detected by a non-plasmonically-enhanced bare optical resonator system in solution is a 25 nm polystyrene sphere1. We have developed a technique known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that can surpass this limit and achieve label-free single molecule detection in aqueous solution2. As signal strength scales with particle volume, our work represents a &#62; 100x improvement in the signal to noise ratio (SNR) over the current state of the art. Here the procedures behind FLOWER are presented in an effort to increase its usage in the field.

We have developed a label-free biosensing system based on optical resonator technology known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that is capable of detecting single molecules in solution. Here the procedures behind this work are described and presented.

无标记单分子检测使用微型环光学谐振器

Detecting small concentrations of molecules down to the single molecule limit has impact on areas such as early detection of disease, and fundamental ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

使用多色荧光检测液滴微流控光纤

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

Determination of Zeta Potential via Nanoparticle Translocation Velocities through a Tunable Nanopore: Using DNA-modified Particles as an Example

Nanopore technologies, known collectively as Resistive Pulse Sensors (RPS), are being used to detect, quantify and characterize proteins, molecules and nanoparticles. Tunable resistive pulse sensing (TRPS) is a relatively recent adaptation to RPS that incorporates a tunable pore that can be altered in real time. Here, we use TRPS to monitor the translocation times of DNA-modified nanoparticles as they traverse the tunable pore membrane as a function of DNA concentration and structure (i.e., single-stranded to double-stranded DNA).
TRPS is based on two Ag/AgCl electrodes, separated by an elastomeric pore membrane that establishes a stable ionic current upon an applied electric field. Unlike various optical-based particle characterization technologies, TRPS can characterize individual particles amongst a sample population, allowing for multimodal samples to be analyzed with ease. Here, we demonstrate zeta potential measurements via particle translocation velocities of known standards and apply these to sample analyte translocation times, thus resulting in measuring the zeta potential of those analytes.
As well as acquiring mean zeta potential values, the samples are all measured using a particle-by-particle perspective exhibiting more information on a given sample through sample population distributions, for example. Of such, this method demonstrates potential within sensing applications for both medical and environmental fields.

Here we use a polyurethane tunable nanopore integrated into a resistive pulse sensing technique to characterize nanoparticles surface chemistry via the measurement of particle translocation velocities, which can be used to determine the zeta potential of individual nanoparticles.

通过通过纳米孔可调纳米易位流速Zeta电位测定：利用DNA修饰颗粒为例

Nanopore technologies, known collectively as Resistive Pulse Sensors (RPS), are being used to detect, quantify and characterize proteins, molecules and ...

Using Extraordinary Optical Transmission to Quantify Cardiac Biomarkers in Human Serum

For a biosensing platform to have clinical relevance in point-of-care (POC) settings, assay sensitivity, reproducibility, and ability to reliably monitor analytes against the background of human serum are crucial.
Nanoimprinting lithography (NIL) was used to fabricate, at a low cost, sensing areas as large as 1.5 mm x 1.5 mm. The sensing surface was made of high-fidelity arrays of nanoholes, each with an area of about 140 nm2. The great reproducibility of NIL made it possible to employ a one-chip, one-measurement strategy on 12 individually manufactured surfaces, with minimal chip-to-chip variation. These nanoimprinted localized surface plasmon resonance (LSPR) chips were extensively tested on their ability to reliably measure a bioanalyte at concentrations varying from 2.5 to 75 ng/mL amidst the background of a complex biofluid-in this case, human serum. The high fidelity of NIL enables the generation of large sensing areas, which in turn eliminates the need for a microscope, as this biosensor can be easily interfaced with a commonly available laboratory light source. These biosensors can detect cardiac troponin in serum with a high sensitivity, at a limit of detection (LOD) of 0.55 ng/mL, which is clinically relevant. They also show low chip-to-chip variance (due to the high quality of the fabrication process). The results are commensurable with widely used enzyme-linked immunosorbent assay (ELISA)-based assays, but the technique retains the advantages of an LSPR-based sensing platform (i.e., amenability to miniaturization and multiplexing, making it more feasible for POC applications).

This work describes a nanoimprinting lithography method to fabricate high-quality sensing arrays that work on the principle of extraordinary optical transmission. The biosensor is low-cost, robust, easy to use, and can detect cardiac troponin I in serum at clinically relevant concentrations (99th percentile cutoff &#8764;10-400 pg/mL, depending on the assay).

用超常光透射法定量测定人血清中的心脏标志物

For a biosensing platform to have clinical relevance in point-of-care (POC) settings, assay sensitivity, reproducibility, and ability to reliably monitor ...

A Protocol for Multiple Gene Knockout in Mouse Small Intestinal Organoids Using a CRISPR-concatemer

CRISPR/Cas9 technology has greatly improved the feasibility and speed of loss-of-function studies that are essential in understanding gene function. In higher eukaryotes, paralogous genes can mask a potential phenotype by compensating the loss of a gene, thus limiting the information that can be obtained from genetic studies relying on single gene knockouts. We have developed a novel, rapid cloning method for guide RNA (gRNA) concatemers in order to create multi-gene knockouts following a single round of transfection in mouse small intestinal organoids. Our strategy allows for the concatemerization of up to four individual gRNAs into a single vector by performing a single Golden Gate shuffling reaction with annealed gRNA oligos and a pre-designed retroviral vector. This allows either the simultaneous knockout of up to four different genes, or increased knockout efficiency following the targeting of one gene by multiple gRNAs. In this protocol, we show in detail how to efficiently clone multiple gRNAs into the retroviral CRISPR-concatemer vector and how to achieve highly efficient electroporation in intestinal organoids. As an example, we show that simultaneous knockout of two pairs of genes encoding negative regulators of the Wnt signaling pathway (Axin1/2 and Rnf43/Znrf3) renders intestinal organoids resistant to the withdrawal of key growth factors.

This protocol describes the steps for cloning multiple single guide RNAs into one guide RNA concatemer vector, which is of particular use in creating multi-gene knockouts using CRISPR/Cas9 technology. The generation of double knockouts in intestinal organoids is shown as a possible application of this method.

使用CRISPR并发剂的小鼠小肠组织中多基因敲除的方案

CRISPR/Cas9 technology has greatly improved the feasibility and speed of loss-of-function studies that are essential in understanding gene function. In ...

Screening and Identification of Small Peptides Targeting Fibroblast Growth Factor Receptor2 using a Phage Display Peptide Library

The human Fibroblast Growth Factor Receptor (FGFR) family comprises four members, namely, FGFR1, FGFR2, FGFR3, and FGFR4, that are involved in various biological activities including cell proliferation, survival, migration and differentiation. Several aberrations in the FGFR signaling pathway, owing to mutations or gene amplification events, have been identified in various types of cancers. Hence, recent research has focused on developing strategies involving therapeutic targeting of FGFRs. Current FGFR inhibitors at various stages of pre-clinical and clinical development include either small molecule inhibitors of tyrosine kinases or monoclonal antibodies, with only a few peptide- based inhibitors in the pipeline. Here, we provide a protocol using phage display technology to screen small peptides as antagonists of FGFR2. Briefly, a library of phage-displayed peptides was incubated in a plate coated with FGFR2. Subsequently, unbound phage was washed off by TBST (TBS + 0.1% [v/v] Tween-20), and bound phage was eluted with 0.2 M glycine-HCl buffer (pH 2.2). The eluted phage was further amplified and used as input for the next round of biopanning. Following three rounds of biopanning, the peptide sequences of individual phage clones were identified by DNA sequencing. Finally, the screened peptides were synthesized and analyzed for affinity and biological activity.

Herein, we present a detailed protocol for screening small peptides that bind to FGFR2 using a phage display peptide library. We further analyze the affinity of the selected peptides toward FGFR2 in vitro and its ability to suppress cell proliferation.

使用噬菌体显示肽库筛选和识别针对纤维细胞生长因子受体2的小肽

The human Fibroblast Growth Factor Receptor (FGFR) family comprises four members, namely, FGFR1, FGFR2, FGFR3, and FGFR4, that are involved in various ...