作者承认罗伯特·W·德基金会，国防威胁降低局（DTRA）和美国国家科学基金会新兴前沿研究和创新（EFRI）的资金支持。作者还感谢马里兰州Nanocenter及其Fablab洁净室设施的支持。

1，微细加工的微流控芯片的<ol><li>准备电化学芯片<ol><li>图案金电极<ol><li>冲洗空白4&#39;硅晶片（黄金级品质）用丙酮，甲醇，异丙醇（“急性心肌梗死”干净）。冲洗从去离子水（DI），随后用N 2枪干燥该晶片的异丙醇。 </li><li>生长出1μm厚的SiO 2钝化层用等离子增强化学气相沉积（PECVD）的工具。存200了厚厚的一层铬其次是2000了厚厚的一层黄金直流溅射工具。 </li><li>自旋“PR1”正光致抗蚀剂（纺丝参数：3000转，1000转/秒，30秒），以创建均匀的膜〜1.6微米厚。预烘烤的晶片在100℃下1分钟的热板上。 </li><li>揭露了190兆焦耳/ 平方厘米，在通过光掩模405纳米波长的晶片。开发晶圆30秒352开发eloper和冲洗晶圆与DI和干与N 2枪。 </li><li>蚀刻金腐蚀剂金1.5分钟。蚀刻铬蚀刻剂〜30秒的铬。冲洗用去离子晶圆干燥与N 2枪。 </li><li>剥去了“急性心肌梗死”清洁过程中的光致抗蚀剂。 注：强氧化剂及有爆炸危险。 </li><li> 1 H 2 SO 4：1分钟的 H 2 O 2的混合物（“食人鱼”干净）与4清洗晶片。冲洗用去离子晶圆干燥与N 2枪。 </li></ol></li><li>图案铂电极<ol><li>自旋“PR2”正光致抗蚀剂（纺丝参数：3000转，1000转/秒，30秒），以创建均匀的膜〜1.4微米厚。预烘烤的晶片在100℃下1分钟的热板上。 </li><li>揭露了30兆焦耳/ 平方厘米，在通过光掩模405纳米波长的晶片。烘烤晶片45秒，在125℃下的热板上。洪水暴露该晶片拥有1000兆焦耳/ 平方厘米在405 nm波长处无光罩。开发晶片在6 2分：1 AZ400K开发商和冲洗用去离子晶圆干燥与N 2枪。 </li><li>沉积400埃厚的钛层，接着用电子束蒸发系统1600厚厚的一层铂。 </li><li>抬离光致抗蚀剂中的超声波处理丙酮浴中5分钟，然后冲洗，用丙酮和异丙醇。冲洗用去离子晶圆干燥与N 2枪。 </li></ol></li></ol></li><li>准备含量频道<ol><li>准备模具的含量频道<ol><li>冲洗空白4&#39;硅晶片（测试等级质量）与“急性心肌梗死”清洁程序。冲洗从用DI晶片的异丙醇，然后用N 2枪干燥。 </li><li>自旋“PR3”负光致抗蚀剂（2步，纺丝参数：步骤1 - 600转，120转/秒，10秒步骤2 - 1150转，383转/秒，27秒），以创建均匀的膜〜100μm厚。预烘烤的热板上（2步烘烤参数晶片：步骤1 - 从室温上升到65℃，在300℃/小时，并保持温度10分钟，第2步 - 斜坡上升至95℃在300℃/小时，并保持温度30分钟）。 </li><li>揭露2500兆焦耳/ 平方厘米，在通过光掩模405纳米波长的晶片。后烘焙晶片逐渐升高至95℃，以300℃/小时，并保持温度有关的热板上10分钟。开发的晶片为在丙二醇单甲醚乙酸酯（PGMEA）显影10分钟。漂洗，用异丙醇和干燥用N 2枪晶片。 </li></ol></li><li>伪造检测通道<ol><li>制备10：1聚二甲基硅氧烷（PDMS）混合物（20克弹性体，2克固化剂）和完全脱气的真空室20分钟。 </li><li>限定的模晶片周围的外壳用铝箔和慢慢倾未固化的PDMS在模具中。 </li><li>烘烤的PDMS在箱式炉中模具（2步烘烤参数：步骤1 - 5分钟，从室温上升到80℃，第2步 - 保持在80℃下为17分钟）。 </li><li>剥掉PDMS从铝箔模具和地点。切开法芯片的外科医生刀，定义孔活检冲压工具。 </li></ol></li></ol></li></ol> 2，装配设备<ol><li>手动对齐PDMS测定通道的电化学芯片上的工作电极。 PDMS枝以及电化学芯片，密封该通道，并防止泄漏。 </li><li>柔性管（外径0.087&#39;及身份证0.015&#39;）连接到一个塑料弯管或直连接器使用的是短挠性管作为适配器（外径0.1875&#39;及身份证0.0625&#39;）。附加连接器连接到每个设备中的穿有孔的入口。 </li><li>连接注射器上的另一端油管，并将注射器注射泵。根据所要求的程序步骤在第3和其相应的溶液中交替地改变设定注射器，管，和一个连接器。 </li></ol> 3，分析DNA杂交请注意：在介绍每个溶液慢慢进入通道以200微升/小时的流速，直到整个信道被充满。 <ol><li>功能化具有不同的单链DNA探针序列每个垂直微通道（并行执行的3个独立的垂直微）： <ol><li>填充每个微通道具有不同的单链DNA探针保温溶液（10mM磷酸盐缓冲液，100 mM氯化钠，10μM磷酸三（2 - 羧乙基）膦（TCEP），和1μM探针的单链DNA），并孵育1小时，然后漂洗所述微通道用PBS。 </li><li>填充微通道用含6 - 巯基-1 - 己醇（MCH）1mM的在10mM的PBS中，100mM的NaCl和1.395毫TCEP的缓冲液中的溶液，并保温（护）软化为1小时，随后漂洗，用PBS将微通道。 </li></ol></li><li>抬离PDMS，旋转90°，水平方向，并将其放置下来，露出了反应室分开行包含一个独特的电极和参比电极（图S1）每一行。 </li><li>填具有4倍的控制测量溶液中的微通道浓缩柠檬酸盐钠（SSC）缓冲液，并温育20分钟。 </li><li>背景测量：填充的微通道用5mM铁氰化钾/ 5mM的亚铁氰化物的PBS溶液，并记录该电化学系统的不同频率的阻抗值（电化学阻抗谱; EIS）使用连接到工作，计数器恒电位，以及参考电极（ EIS参数：频率范围为1 MHz至0.1赫兹，每十年10个频率点的数据，25 mV的幅度，5 mV的极化与参比电极）。重复此测量中的微通道的每个工作电极。 </LI&gt; <li>测量DNA杂交（对于每个非互补的，互补的单链DNA靶执行）。 <ol><li>填充微通道具有4倍的目标单链DNA测定溶液浓缩含有1μM的目标单链DNA的SSC缓冲液，并温育20分钟。测量DNA根据步骤3.4。 </li></ol></li></ol>

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Acta. 643, 26-37 (2009).</li><li>Arinaga, K., Rant, U., Tornow, M., Fujita, S., Abstreiter, G., Yokoyama, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+surface+charging+during+the+coadsorption+of+mercaptohexanol+to+DNA+layers+on+gold:+Direct+observation+of+desorption+and+layer+reorientation.">The role of surface charging during the coadsorption of mercaptohexanol to DNA layers on gold: Direct observation of desorption and layer reorientation.</a> Langmuir. 22, 5560-5562 (2006).</li><li>Katz, E., Willner, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+biomolecular+interactions+at+conductive+and+semiconductive+surfaces+by+impedance+spectroscopy:+Routes+to+impedimetric+immunosensors,+DNA-sensors,+and+enzyme+biosensors.">Probing biomolecular interactions at conductive and semiconductive surfaces by impedance spectroscopy: Routes to impedimetric immunosensors, DNA-sensors, and enzyme biosensors.</a> Electroanalysis. 15, 913-947 (2003).</li></ol>

作者什么都没有透露。

我们的方法展示出一种微流体为基础的电化学生物芯片的制造和利用的DNA杂交的事件分析。通过高收益率来控制微细加工过程中，我们开发包括集成电化学传感器阵列微型通道的设备。我们已经通过迭代的方法设计用于电化学芯片和微流体通道模具的光刻过程控制处理参数。这些步骤为其他微型分析仪器未来创造的指导方针。重要的是，它们提供了一种方法，以优化各种生物感测的参数，如信号 ...

微流控芯片实验室级芯片（LOC）的设备提供众多优势，在临床诊断，环境监测和生物医学研究。这些器件利用微流体通道，以控制流体流动的芯片，其中各种程序可发生包括试剂的混合，基于结合亲和力，信号转导和细胞培养1-4的区域。微流控技术提供了许多优点比传统的临床诊断工具，如微孔板读者或电泳凝胶迁移实验。微流体器件需要的大小为2〜3个数量级（纳升，而不是微升）更少的试剂来执行类似分析。此外，这些设备可以增加通过其中的一些生物学事件的发生是由于在物种内的通道5,6越小约束的速度。第三，传感器可以在使用光刻技术和蚀刻技术的微流体装置，其可以提供无标记detectio被集成ñ。最后，这些装置是廉价的，以产生与需要的操作7-10技术人员的部分少的工作。 标签的检测通常是使用光学或电气传感器执行。光学器件可以是由于与样品中的分析物低干扰呈现更好的感测性能。然而，他们的表现受到损害的情况下样品的背景具有相同的共振波长的传感器11。有许多优点，使用电信号来执行生物和化学检测在微流体系统中。制造本质上是较不复杂的，因为这些传感器通常只需要图案化电极来操作。此外，电信号可以直接与具有最高的测量设备，而其它信号模式可能要求换能器的信号12-15转换。电子传感器通常测量的变化impedancê16,17，电容18，或氧化还原活性19。然而，新的挑战表示为这些系统的小型化。要克服的最重要的挑战包括：样品制备和流体（由于低的样品体积和雷诺数）的混合，物理和化学作用（包括毛细管力，表面粗糙度，建筑材料和分析物之间的化学相互作用），低信号 - 噪比20-23，并从复杂的生物样品（ 例如 ，血液和唾液）中电活性分析物的潜在干扰（通过减小的表面积和体积。生产）。这些影响进一步的调查将导致在可重复的方式处理这些设备，将改善其整体性能的精确制造和操作指南。 用于DNA杂交检测广泛诊断遗传性疾病24,25和各种形式的CANC呃26。每年，流感多株被确定使用从DNA杂交技术，结果27例患者。流感病毒就占每年36,000人死亡，在美国28。这样的例子可能受益于在不牺牲灵敏度或特异性可以执行相同的分析技术如用低的样品体积的板读取器或凝胶移位分析，并在成本的一小部分台式微流体装置。由于无标记的电化学传感的许多优点，它已被广泛地用于检测DNA杂交事件29,30。其中宏观尺度的电极（在毫米范围内）浸在烧杯中与感兴趣的溶液A的设置可以被用于提供关于单链DNA序列的结合动力学它们匹配的互补序列非常敏感数据。最近，一直在结合电化学传感MICR几进展ofluidics的DNA杂交。研究已经完成对杂交动力学31和传感器整合在微流体通道检测15。然而，仍然需要一种能够分析DNA杂交事件在平行无需复杂的样品制备步骤的快速高通量微流体装置。 在这项工作中提出的设备提供了一个平台，允许多个交互并行，没有复杂的样品制备步骤进行筛选。我们的协议介绍如何微流体为基础的电化学生物芯片的微细加工和微机电系统（MEMS）技术32,33。我们描述的两个微流体芯片，聚二甲基硅氧烷制成（PDMS），以及电化学芯片的制造过程中，由电极阵列。生物芯片的化学官能与单链DNA探针也被解决。最后，ABIL生物传感器的性特异性检测和分析的ssDNA目标是证明。总体而言，微流体为基础的电化学生物芯片是一种快速和高通量分析技术。它可以被用于研究生物分子和导电换能器之间的相互作用，并能在各种上实验室芯片应用中使用。

<table border="0" cellpadding="0" cellspacing="0" width="765">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Name of Material/ Equipment</td>
			<td style="width:155px;">Company</td>
			<td style="width:227px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Material</td>
			<td style="width:155px;"></td>
			<td style="width:227px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">4&#39;&#39; Silicon wafer</td>
			<td style="width:155px;">Ultrasil</td>
			<td style="width:227px;">4-5664</td>
			<td>Single side polished; P-type; Boron doped; Orientation 1-0-0; Thickness 500 micron; Resistance 10-20 ohm*cm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Shipley 1813 photoresist (&#34;PR1&#34;)</td>
			<td style="width:155px;">Microchem</td>
			<td style="width:227px;"></td>
			<td style="width:167px;">positive photoresist</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">AZ5214 photoresist (&#34;PR2&#34;)</td>
			<td style="width:155px;">Hoechst Celanse</td>
			<td style="width:227px;"></td>
			<td style="width:167px;">positive photoresist</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">SU-8 50 photoresist (&#34;PR3&#34;)</td>
			<td style="width:155px;">Microchem</td>
			<td style="width:227px;"></td>
			<td style="width:167px;">negative photoresist</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gold etchant</td>
			<td style="width:155px;">Transene</td>
			<td style="width:227px;">TFA</td>
			<td style="width:167px;">No dilution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chromium etchant</td>
			<td style="width:155px;">Transene</td>
			<td style="width:227px;">1020AC</td>
			<td style="width:167px;">No dilution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PDMS elastomer</td>
			<td style="width:155px;">Dow Corning</td>
			<td style="width:227px;">3097366 1004</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PDMS curing agent</td>
			<td style="width:155px;">Dow Corning</td>
			<td style="width:227px;">3097358 1004</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Biopsy punching tool</td>
			<td style="width:155px;">Healthlink</td>
			<td style="width:227px;">BP20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tygon flexible tubing</td>
			<td style="width:155px;">Cole Parmer&#160;</td>
			<td style="width:227px;">R 3603</td>
			<td>.015&#34;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tygon flexible adapter</td>
			<td style="width:155px;">Cole Parmer&#160;</td>
			<td style="width:227px;">06417-41</td>
			<td>.0625&#34;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1 mL syringe</td>
			<td style="width:155px;">Beckton-Dickenson</td>
			<td align="right" style="width:227px;">301025</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Monobasic potassium phosphate</td>
			<td style="width:155px;">Fluka</td>
			<td align="right" style="width:227px;">1551139</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Potassium phosphate dibasic anhydrous</td>
			<td style="width:155px;">Sigma</td>
			<td style="width:227px;">RES20765-A7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium chloride</td>
			<td style="width:155px;">Sigma-Aldrich</td>
			<td style="width:227px;">S7653</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">tris(2-carboxyethyl)phosphine</td>
			<td style="width:155px;">Aldrich</td>
			<td style="width:227px;">C4706</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">6-mercapto-1-hexanol</td>
			<td style="width:155px;">Aldrich</td>
			<td align="right" style="width:227px;">451088</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">20x concentrated saline-sodium citrate buffer</td>
			<td style="width:155px;">Sigma</td>
			<td align="right" style="width:227px;">93017</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Potassium hexacyanoferrate(III)</td>
			<td style="width:155px;">Aldrich</td>
			<td align="right" style="width:227px;">455946</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium ferrocyanide</td>
			<td style="width:155px;">Aldrich</td>
			<td style="width:227px;">CDS001589</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Target ssDNA #1</td>
			<td style="width:155px;">Integrated DNA Technologies (IDT)</td>
			<td style="width:227px;">100 nmole DNA oligo</td>
			<td>5&#8217;-/5ThioMC6-D/AAAGCTCCGATAGCGCTCCG 
			TGGACGTCCC-3&#8217;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Complementary ssDNA #1</td>
			<td style="width:155px;">Integrated DNA Technologies (IDT)</td>
			<td style="width:227px;">100 nmole DNA oligo</td>
			<td>5&#8217;-GGGACGTCCACGGAGCGCTA 
			TCGGAGCTTT-3&#8217;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Target ssDNA #2</td>
			<td style="width:155px;">Integrated DNA Technologies (IDT)</td>
			<td style="width:227px;">100 nmole DNA oligo</td>
			<td>5&#8217;-/5ThioMC6-D/ACGCGTCAGGTCATTGACGA 
			ATCGATGAGT-3&#8217;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Complementary ssDNA #2</td>
			<td style="width:155px;">Integrated DNA Technologies (IDT)</td>
			<td style="width:227px;">100 nmole DNA oligo</td>
			<td>5&#8217;-ACTCATCGATTCGTCAATGA 
			CCTGACCCGT-3&#8217;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Target ssDNA #3</td>
			<td style="width:155px;">Integrated DNA Technologies (IDT)</td>
			<td style="width:227px;">100 nmole DNA oligo</td>
			<td>5&#8217;-/5ThioMC6-D/ACCTAGATCCAGTAGTTAGA 
			CCCATGATGA-3&#8217;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Complementary ssDNA #3</td>
			<td style="width:155px;">Integrated DNA Technologies (IDT)</td>
			<td style="width:227px;">100 nmole DNA oligo</td>
			<td>5&#8217;-TCATCATGGGTCTAACTACT 
			GGATCTAGGT-3&#8217;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:155px;"></td>
			<td style="width:227px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Instrument</td>
			<td style="width:155px;"></td>
			<td style="width:227px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Plasma Enhanced Chemical Vapor Deposition (PECVD)</td>
			<td style="width:155px;">Oxford Instruments</td>
			<td style="width:227px;">PlasmaLab System 100</td>
			<td>Chamber pressure 1000 mTorr, Tempreture 200 celsius degrees, RF power 20 W, Gasses: a) N2O flow rate 710 sccm; b) a composition of 5% SiH4 and 95% N2 gasses flow rate 170 sccm, SiO2 growth rate 690 Angstrom/minute.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DC sputtering unit</td>
			<td style="width:155px;">AJA International</td>
			<td style="width:227px;">ATC 1800-V</td>
			<td>For Chrome: Chamber pressure 10 mTorr, Argon flow rate 20 sccm, Supplied DC power 200 W, Sputter rate 10 nm/min. For Gold: Chamber pressure 10 mTorr, Argon flow rate 20 sccm, Supplied DC power 200 W, Sputter rate 36 nm/min.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">E-beam evaporation system</td>
			<td style="width:155px;">Denton</td>
			<td style="width:227px;">Custom-built</td>
			<td>For Titanium: Chamber pressure &#60;2E-6 Torr, Supplied power to the e-gun 7.5k W, Filament current 150-200 mA, Evaporation rate 6-10 Angstrom/second. For Platinum: Chamber pressure &#60;2E-6 Torr, Supplied power to the e-gun 7.5k W, Filament current 150-200 mA, Evaporation rate 2-3 Angstrom/second.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Potentiostat</td>
			<td style="width:155px;">CH Instruments</td>
			<td style="width:227px;">660D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Syringe pump</td>
			<td style="width:155px;">KD Scientific</td>
			<td style="width:227px;">KDS230</td>
			<td></td>
		</tr>
	</tbody>
</table>

a microfluidic-based electrochemical biochip for label-free dna hybridization analysis

分析台式程序进入微规模的小型化提供显著优点在关于反应时间，成本和集成的预处理步骤。利用这些设备对的DNA杂交事件的分析是重要的，因为它提供了一种技术，生物标志物的实时评估，在点的护理各种疾病。然而，当该装置的足迹减少的各种物理现象的增加的优势地位。这些现象影响了制造精度和设备的运行可靠性。因此，存在很大的需求，以改善总体性能精确制造和操作中的可重现的方式处理这些装置。在这里，我们描述的协议和用于制造和微流体为基础的电化学生物芯片的DNA的杂交事件的准确分析的操作方法。生物芯片是由两部分组成：一个微流体芯片与三个平行的微通道进行聚二甲基硅氧烷（PDMS），以及一个3×3阵列的电化学微芯片。采用电化学阻抗谱（EIS）分析，检测到的DNA杂交的事件。 EIS的分析，可以在电化学系统中是主要的，在这些尺度的特性的监视的变化。与以监测电荷转移和扩散阻力与生物传感器的变化的能力，我们证明以下20分钟的选择性互补的单链DNA靶，380纳米的计算检测限，并且13％的交叉反应性与其他非互补单链DNA孵化。这种方法可以通过阐明上扩散在微观尺度制度的行为，以及允许的DNA杂交事件的研究提高微型设备的性能。

可控和精确的制造工艺进行实验装置的研究是必不可少的。这使研究人员能够获得重复性和高通量实验。在这里，我们表现出了高产量，高重复性的微细加工过程中的微流体为基础的电化学生物芯片（ 图1）。具有故障率低，一些设备已经表明，导致溶液的泄漏结合的问题。为了验证生物芯片的电化学活性，循环伏安法测量在充有电活性的氧化还原对铁氰化物/亚铁氰化物的微通道进?...

Watch this Scientific Journal Video about A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis at JoVE.com

A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis

我们提出了一个微流体为基础的电化学生物芯片的DNA杂交检测。以下的ssDNA探针官能化，特异性，灵敏度和检测极限进行了研究具有互补和非互补ssDNA的目标。结果表明在电化学系统中的DNA杂交事件的影响，以3.8纳米的检测极限。

微流体为基础的电化学生物芯片的无标记的DNA杂交分析

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration ...

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JoVE Journal

Bioengineering

17.0K 次观看.  University of Maryland. 我们提出了一个微流体为基础的电化学生物芯片的DNA杂交检测。以下的ssDNA探针官能化，特异性，灵敏度和检测极限进行了研究具有互补和非互补ssDNA的目标。结果表明在电化学系统中的DNA杂交事件的影响，以3.8纳米的检测极限。 

视频: A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis

A Microfluidic-based Hydrodynamic Trap for Single Particles

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in concentrated or crowded particle suspensions, which is difficult using alternative force field-based trapping methods. The hydrodynamic trap is user-friendly, straightforward to implement and may be added to existing microfluidic devices to facilitate trapping and long-time analysis of particles. Overall, the hydrodynamic trap is a new platform for confinement, micromanipulation, and observation of particles without surface immobilization and eliminates the need for potentially perturbative optical, magnetic, and electric fields in the free-solution trapping of small particles.

In this article, we present a microfluidic-based method for particle confinement based on hydrodynamic flow. We demonstrate stable particle trapping at a fluid stagnation point using a feedback control mechanism, thereby enabling confinement and micromanipulation of arbitrary particles in an integrated microdevice.

一个单粒子为基础的微流控液力陷阱

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science.  Methods for ...

科研

生物工程

Fabrication of Electrochemical-DNA Biosensors for the Reagentless Detection of Nucleic Acids, Proteins and Small Molecules

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to 
receive the results. Many patients would be better served by rapid, bedside tests. To this end our laboratory and others have developed a versatile, reagentless 
biosensor platform that supports the quantitative, reagentless, electrochemical detection of nucleic acids (DNA, RNA), proteins (including antibodies) and small 
molecules analytes directly in unprocessed clinical and environmental samples. In this video, we demonstrate the preparation and use of several biosensors in this 
"E-DNA" class. In particular, we fabricate and demonstrate sensors for the detection of a target DNA sequence in a polymerase chain reaction mixture, an HIV-specific antibody and the drug cocaine. The preparation procedure requires only three hours of hands-on effort followed by an overnight incubation, and their use requires only minutes.

"E-DNA" sensors, reagentless, electrochemical biosensors that perform well even when challenged directly in blood and other complex matrices, have been adapted to the detection of a wide range of nucleic acid, protein and small molecule analytes. Here we present a general procedure for the fabrication and use of such sensors.

无试剂检测核酸，蛋白质和小分子的电化学DNA生物传感器的制备

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to 
receive the results. ...

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, currently available routine methods require processing steps and alter sample integrity. Raman spectroscopy is a fast method that enables the measurement of biological samples without the need for further processing steps. This laser-based technology detects the inelastic scattering of monochromatic light.6 As every chemical vibration is assigned to a specific Raman band (wavenumber in cm-1), each biological sample features a typical spectral pattern due to their inherent biochemical composition.7-9 Within Raman spectra, the peak intensities correlate with the amount of the present molecular bonds.1 Similarities and differences of the spectral data sets can be detected by employing a multivariate analysis (e.g. principal component analysis (PCA)).10
Here, we perform Raman spectroscopy of living cells and native tissues. Cells are either seeded on glass bottom dishes or kept in suspension under normal cell culture conditions (37 &deg;C, 5% CO2) before measurement. Native tissues are dissected and stored in phosphate buffered saline (PBS) at 4 &deg;C prior measurements. Depending on our experimental set up, we then either focused on the cell nucleus or extracellular matrix (ECM) proteins such as elastin and collagen. For all studies, a minimum of 30 cells or 30 random points of interest within the ECM are measured. Data processing steps included background subtraction and normalization.

Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.

非接触，无标签使用拉曼光谱研究细胞和细胞外基质的监测

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, ...

Hollow Microneedle-based Sensor for Multiplexed Transdermal Electrochemical Sensing

The development of a minimally invasive multiplexed monitoring system for rapid analysis of biologically-relevant molecules could offer individuals suffering from chronic medical conditions facile assessment of their immediate physiological state. Furthermore, it could serve as a research tool for analysis of complex, multifactorial medical conditions. In order for such a multianalyte sensor to be realized, it must be minimally invasive, sampling of interstitial fluid must occur without pain or harm to the user, and analysis must be rapid as well as selective.
Initially developed for pain-free drug delivery, microneedles have been used to deliver vaccines and pharmacologic agents (e.g., insulin) through the skin.1-2 Since these devices access the interstitial space, microneedles that are integrated with microelectrodes can be used as transdermal electrochemical sensors. Selective detection of glucose, glutamate, lactate, hydrogen peroxide, and ascorbic acid has been demonstrated using integrated microneedle-electrode devices with carbon fibers, modified carbon pastes, and platinum-coated polymer microneedles serving as transducing elements.3-7,8
This microneedle sensor technology has enabled a novel and sophisticated analytical approach for in situ and simultaneous detection of multiple analytes. Multiplexing offers the possibility of monitoring complex microenvironments, which are otherwise difficult to characterize in a rapid and minimally invasive manner. For example, this technology could be utilized for simultaneous monitoring of extracellular levels of, glucose, lactate and pH,9 which are important metabolic indicators of disease states7,10-14 (e.g., cancer proliferation) and exercise-induced acidosis.15

This article details the construction of a multiplexed microneedle-based sensor. The device is being developed for in situ sampling and electrochemical analysis of multiple analytes in a rapid and selective manner. We envision clinical medicine and biomedical research uses for these microneedle-based sensors.

复透皮电化学传感的空心微针为基础的传感器

The development of a minimally invasive multiplexed monitoring system for rapid analysis of biologically-relevant molecules could offer individuals ...

Bacterial Detection &amp; Identification Using Electrochemical Sensors

Electrochemical sensors are widely used for rapid and accurate measurement of blood glucose and can be adapted for detection of a wide variety of analytes. Electrochemical sensors operate by transducing a biological recognition event into a useful electrical signal. Signal transduction occurs by coupling the activity of a redox enzyme to an amperometric electrode. Sensor specificity is either an inherent characteristic of the enzyme, glucose oxidase in the case of a glucose sensor, or a product of linkage between the enzyme and an antibody or probe.
Here, we describe an electrochemical sensor assay method to directly detect and identify bacteria. In every case, the probes described here are DNA oligonucleotides. This method is based on sandwich hybridization of capture and detector probes with target ribosomal RNA (rRNA). The capture probe is anchored to the sensor surface, while the detector probe is linked to horseradish peroxidase (HRP). When a substrate such as 3,3',5,5'-tetramethylbenzidine (TMB) is added to an electrode with capture-target-detector complexes bound to its surface, the substrate is oxidized by HRP and reduced by the working electrode. This redox cycle results in shuttling of electrons by the substrate from the electrode to HRP, producing current flow in the electrode.

We describe an electrochemical sensor assay method for rapid bacterial detection and identification. The assay involves a sensor array functionalized with DNA oligonucleotide capture probes for ribosomal RNA (rRNA) species-specific sequences. Sandwich hybridization of target rRNA with the capture probe and a horseradish peroxidase-linked DNA oligonucleotide detector probe produces a measurable amperometric current.

使用电化学传感器的细菌检测和鉴定

Electrochemical  sensors are widely used for rapid and accurate measurement of blood glucose and  can be adapted for detection of a wide variety of ...

Multi-analyte Biochip (MAB) Based on All-solid-state Ion-selective Electrodes (ASSISE) for Physiological Research

Lab-on-a-chip (LOC) applications in environmental, biomedical, agricultural, biological, and spaceflight research require an ion-selective electrode (ISE) that can withstand prolonged storage in complex biological media 1-4. An all-solid-state ion-selective-electrode (ASSISE) is especially attractive for the aforementioned applications. The electrode should have the following favorable characteristics: easy construction, low maintenance, and (potential for) miniaturization, allowing for batch processing. A microfabricated ASSISE intended for quantifying H+, Ca2+, and CO32- ions was constructed. It consists of a noble-metal electrode layer (i.e. Pt), a transduction layer, and an ion-selective membrane (ISM) layer. The transduction layer functions to transduce the concentration-dependent chemical potential of the ion-selective membrane into a measurable electrical signal.
The lifetime of an ASSISE is found to depend on maintaining the potential at the conductive layer/membrane interface 5-7. To extend the ASSISE working lifetime and thereby maintain stable potentials at the interfacial layers, we utilized the conductive polymer (CP) poly(3,4-ethylenedioxythiophene) (PEDOT) 7-9 in place of silver/silver chloride (Ag/AgCl) as the transducer layer. We constructed the ASSISE in a lab-on-a-chip format, which we called the multi-analyte biochip (MAB) (Figure 1).
Calibrations in test solutions demonstrated that the MAB can monitor pH (operational range pH 4-9), CO32- (measured range 0.01 mM - 1 mM), and Ca2+ (log-linear range 0.01 mM to 1 mM). The MAB for pH provides a near-Nernstian slope response after almost one month storage in algal medium. The carbonate biochips show a potentiometric profile similar to that of a conventional ion-selective electrode. Physiological measurements were employed to monitor biological activity of the model system, the microalga Chlorella vulgaris.
The MAB conveys an advantage in size, versatility, and multiplexed analyte sensing capability, making it applicable to many confined monitoring situations, on Earth or in space.
Biochip Design and Experimental Methods
The biochip is 10 x 11 mm in dimension and has 9 ASSISEs designated as working electrodes (WEs) and 5 Ag/AgCl reference electrodes (REs). Each working electrode (WE) is 240 &mu;m in diameter and is equally spaced at 1.4 mm from the REs, which are 480 &mu;m in diameter. These electrodes are connected to electrical contact pads with a dimension of 0.5 mm x 0.5 mm. The schematic is shown in Figure 2.
Cyclic voltammetry (CV) and galvanostatic deposition methods are used to electropolymerize the PEDOT films using a Bioanalytical Systems Inc. (BASI) C3 cell stand (Figure 3). The counter-ion for the PEDOT film is tailored to suit the analyte ion of interest. A PEDOT with poly(styrenesulfonate) counter ion (PEDOT/PSS) is utilized for H+ and CO32-, while one with sulphate (added to the solution as CaSO4) is utilized for Ca2+. The electrochemical properties of the PEDOT-coated WE is analyzed using CVs in redox-active solution (i.e. 2 mM potassium ferricyanide (K3Fe(CN)6)). Based on the CV profile, Randles-Sevcik analysis was used to determine the effective surface area 10. Spin-coating at 1,500 rpm is used to cast ~2 &mu;m thick ion-selective membranes (ISMs) on the MAB working electrodes (WEs).
The MAB is contained in a microfluidic flow-cell chamber filled with a 150 &mu;l volume of algal medium; the contact pads are electrically connected to the BASI system (Figure 4). The photosynthetic activity of Chlorella vulgaris is monitored in ambient light and dark conditions.

Multi-analyte Biochip MAB Based on All-solid-state Ion-selective Electrodes ASSISE for Physiological Research

All-solid-state ion-selective electrodes (ASSISEs) constructed from a conductive polymer (CP) transducer provide several months of functional lifetime in liquid media. Here, we describe the fabrication and calibration process of ASSISEs in a lab-on-a-chip format. The ASSISE is demonstrated to have maintained a near-Nernstian slope profile after prolonged storage in complex biological media.

多分析物生物芯片（MAB），基于全固态离子选择性电极（ASSISE）的生理研究

Lab-on-a-chip (LOC) applications in environmental, biomedical, agricultural, biological, and spaceflight research require an ion-selective electrode (ISE) ...

Microfluidic-based Electrotaxis for On-demand Quantitative Analysis of Caenorhabditis elegans' Locomotion

The nematode Caenorhabditis elegans is a versatile model organism for biomedical research because of its conservation of disease-related genes and pathways as well as its ease of cultivation. Several C. elegans disease models have been reported, including neurodegenerative disorders such as Parkinson's disease (PD), which involves the degeneration of dopaminergic (DA) neurons 1. Both transgenes and neurotoxic chemicals have been used to induce DA neurodegeneration and consequent movement defects in worms, allowing for investigations into the basis of neurodegeneration and screens for neuroprotective genes and compounds 2,3.
Screens in lower eukaryotes like C. elegans provide an efficient and economical means to identify compounds and genes affecting neuronal signaling. Conventional screens are typically performed manually and scored by visual inspection; consequently, they are time-consuming and prone to human errors. Additionally, most focus on cellular level analysis while ignoring locomotion, which is an especially important parameter for movement disorders.
We have developed a novel microfluidic screening system (Figure 1) that controls and quantifies C. elegans' locomotion using electric field stimuli inside microchannels. We have shown that a Direct Current (DC) field can robustly induce on-demand locomotion towards the cathode ("electrotaxis") 4. Reversing the field's polarity causes the worm to quickly reverse its direction as well. We have also shown that defects in dopaminergic and other sensory neurons alter the swimming response 5. Therefore, abnormalities in neuronal signaling can be determined using locomotion as a read-out. The movement response can be accurately quantified using a range of parameters such as swimming speed, body bending frequency and reversal time.
Our work has revealed that the electrotactic response varies with age. Specifically, young adults respond to a lower range of electric fields and move faster compared to larvae 4. These findings led us to design a new microfluidic device to passively sort worms by age and phenotype 6.
We have also tested the response of worms to pulsed DC and Alternating Current (AC) electric fields. Pulsed DC fields of various duty cycles effectively generated electrotaxis in both C. elegans and its cousin C. briggsae 7. In another experiment, symmetrical AC fields with frequencies ranging from 1 Hz to 3 KHz immobilized worms inside the channel 8.
Implementation of the electric field in a microfluidic environment enables rapid and automated execution of the electrotaxis assay. This approach promises to facilitate high-throughput genetic and chemical screens for factors affecting neuronal function and viability.

Microfluidic-based Electrotaxis for On-demand Quantitative Analysis of Caenorhabditis elegans&#039; Locomotion

A semi-automated micro-electro-fluidic method to induce on-demand locomotion in Caenorhabditis elegans is described. This method is based on the neurophysiologic phenomenon of worms responding to mild electric fields (&#x201C;electrotaxis&#x201D;) inside microfluidic channels. Microfluidic electrotaxis serves as a rapid, sensitive, low-cost, and scalable technique to screen for factors affecting neuronal health.

基于微流体Electrotaxis的，为按需定量分析<em&gt;线虫</em&gt;&#39;LOCOMOTION的

The nematode Caenorhabditis elegans is a versatile model organism for biomedical research because of its conservation of disease-related genes and ...

Use of Label-free Optical Biosensors to Detect Modulation of Potassium Channels by G-protein Coupled Receptors

Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma membrane1. To regulate neuronal excitability, the biophysical properties of ion channels are modified by signaling proteins and molecules, which often bind to the channels themselves to form a heteromeric channel complex2,3. Traditional assays examining the interaction between channels and regulatory proteins require exogenous labels that can potentially alter the protein&#39;s behavior and decrease the physiological relevance of the target, while providing little information on the time course of interactions in living cells. Optical biosensors, such as the X-BODY Biosciences BIND Scanner system, use a novel label-free technology, resonance wavelength grating (RWG) optical biosensors, to detect changes in resonant reflected light near the biosensor. This assay allows the detection of the relative change in mass within the bottom portion of living cells adherent to the biosensor surface resulting from ligand induced changes in cell adhesion and spreading, toxicity, proliferation, and changes in protein-protein interactions near the plasma membrane. RWG optical biosensors have been used to detect changes in mass near the plasma membrane of cells following activation of G protein-coupled receptors (GPCRs), receptor tyrosine kinases, and other cell surface receptors. Ligand-induced changes in ion channel-protein interactions can also be studied using this assay. In this paper, we will describe the experimental procedure used to detect the modulation of Slack-B sodium-activated potassium (KNa) channels by GPCRs.

Optical biosensor techniques can detect changes in mass near the plasma membrane in living cells and allow one to follow cellular responses in both individual cells and populations of cells. This protocol will describe detection of the modulation of potassium channels by G-protein coupled receptors in intact cells using this approach.

使用无标记光学生物传感器由G-蛋白偶联受体，以检测钾通道的调制

Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma ...

A Label-free Technique for the Spatio-temporal Imaging of Single Cell Secretions

Inter-cellular communication is an integral part of a complex system that helps in maintaining basic cellular activities. As a result, the malfunctioning of such signaling can lead to many disorders. To understand cell-to-cell signaling, it is essential to study the spatial and temporal nature of the secreted molecules from the cell without disturbing the local environment. Various assays have been developed to study protein secretion, however, these methods are typically based on fluorescent probes which disrupt the relevant signaling pathways. To overcome this limitation, a label-free technique is required.
In this paper, we describe the fabrication and application of a label-free localized surface plasmon resonance imaging (LSPRi) technology capable of detecting protein secretions from a single cell. The plasmonic nanostructures are lithographically patterned onto a standard glass coverslip and can be excited using visible light on commercially available light microscopes. Only a small fraction of the coverslip is covered by the nanostructures and hence this technique is well suited for combining common techniques such as fluorescence and bright-field imaging.
A multidisciplinary approach is used in this protocol which incorporates sensor nanofabrication and subsequent biofunctionalization, binding kinetics characterization of ligand and analyte, the integration of the chip and live cells, and the analysis of the measured signal. As a whole, this technology enables a general label-free approach towards mapping cellular secretions and correlating them with the responses of nearby cells.

Inter-cellular communication is critical for controlling various physiological activities within and outside the cell. This paper describes a protocol for measuring the spatio-temporal nature of single cell secretions. To achieve this, a multidisciplinary approach is used which integrates label-free nanoplasmonic sensing with live cell imaging.

无标记技术的单细胞分泌物的时空成像

Inter-cellular communication is an integral part of a complex system that helps in maintaining basic cellular activities. As a result, the malfunctioning ...

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 ...