通过胶体粒子自组装过程创建在PDMS微流控芯片分50纳米的纳米流体结
Summary
We propose a simple self-assembly technique of silica colloidal nanoparticles to create a nanofluidic junction between two microchannels in polydimethylsiloxane (PDMS). Using this technique, a nanoporous bead membrane with a pore size down to ~45 nm was built inside a microchannel and applied to electrokinetic preconcentration of DNA samples.
Abstract
聚二甲基硅氧烷（PDMS）是普遍的建筑材料，使微流体装置，因为它易于成型和粘合的以及它的透明度。由于PDMS材料的柔软性，但是，它是具有挑战性的使用PDMS用于构建纳米通道。渠道往往等离子体结合过程中容易崩溃。在本文中，我们提出了二氧化硅胶体纳米粒子的蒸发驱动的自组装方法与子50 2微之间50nm孔纳流控创建路口。孔尺寸以及表面电荷的纳米流体交界的是可调简单地由自组装过程之前，改变组装微流体装置的外胶体二氧化硅珠尺寸和表面官能在小瓶中。使用具有300纳米，500纳米，900纳米的珠粒度的纳米颗粒的自组装，有可能分别与〜45纳米的孔隙尺寸，〜75 nm和〜135毫微米，制作多孔膜。在电人的潜力，这种纳米膜发起离子浓差极化（ICP）作为阳离子选择性膜15分钟内集中精力靠〜1700倍的DNA。这种非光刻纳米制造工艺开辟了建立一个PDMS微流控芯片内的离子和分子纳米运输过程的研究可调谐纳米流体结了新的契机。
Introduction
纳流控是μTAS的一个新兴的研究领域（微全分析系统）在10 1的长度尺度来研究生物过程或离子的迁移现象和分子- 10 2纳米。用的纳米流体的工具，如纳米通道的到来，分子和离子的输运过程可以以前所未有的精度进行监测和操纵，如果需要的话，通过利用只在该长度尺度对分离和检测是可用的功能。1,2之一这些特征纳米级特征是表面以在纳米通道散装电荷（或Dukhin数）的高比例，可能会导致电荷不平衡，并启动纳米通道和微通道之间的离子浓度极化（ICP）。3
对于纳米流体现象的研究一种常见的设备平台包括由纳米通道作为结的阵列连接的两个微通道系统。4-6 </sup>用于构建这样的纳米流体装置的选择的材料是硅，因为它的高刚度，防止信道从期间接合工艺倒塌7然而，硅器件制造需要昂贵的掩模和在洁净室设备处理的大量。8- 10由于装置制造的，通过模制和等离子体结合，聚二甲基硅氧烷（PDMS）的便利性已被广泛接受的作为建筑材料为微流体，这将是对纳米流体的理想材料为好。然而，它的杨氏模量低周围360-870千帕，使得等离子体接合时与PDMS通道容易可折叠的。纳米通道（宽深）的最小长宽比必须小于10：1，这意味着通过标准光刻PDMS器件的制造会变得极具挑战性的，如果纳通道深度必须小于100纳米，需要一个信道宽度小于photolith的电流限制地理学在约1微米。为了克服这一限制，已经尝试来创建使用非光刻方法在PDMS纳通道如拉伸以引发裂纹等离子处理后的78纳米11或形成皱纹平均深度12塌陷允许用机械压力将PDMS通道一纳通道的高度低至60纳米。13
即使这些高度发明的非光刻方法允许低于100nm建筑纳通道中的深度，纳米通道制造的尺寸可控性仍对阻碍一个广泛接受的PDMS作为建筑材料为纳米流体装置。纳米通道的另一个关键问题，无论是在硅或PDMS，是在壳体的表面官能有必要改变对离子或分子的操纵通道壁的表面电荷。通过连接装置组装后，纳米通道是非常困难达到表面官能由于扩散限制运输。创建具有高尺寸精确度的和容易的表面官能纳米级信道，在微流体装置引起的蒸发14-16胶体粒子的自组装法可以是有前途的方法之一。除了 孔尺寸和表面特性的可控性，甚至有可能以调谐使用涂有聚电解质的胶体粒子时在原位通过控制温度，17的pH值，18,19和离子强度的细孔的尺寸。18由于这些对于毛细管电，20生物传感器，21蛋白浓度22以及微流体蛋白质和DNA的分离。14,23在这项研究中的优势，胶体粒子的自组装方法已经找到的应用程序，我们部署这种自组装方法来构建在电动富集装置PDMS需要两个微通道之间的纳米流体结24的电动浓度背后的基本机制是基于离子浓度极化（ICP）。包括在以下方案25的制造和装配步骤的详细描述。
Protocol
Representative Results
Discussion
继通用设备设计方案，研究纳米流体，我们用胶体纳米粒子的蒸发驱动的自组装，而不是光刻图案纳米通道阵列制造的两微流体通道之间的纳米流体连接处。当流动的胶体粒子进入珠输送通道，nanotraps的具有700nm的深度和2微米的小珠传送通道的两侧，在100微米的总宽度的宽度的阵列防止珠悬浮液流入缓冲液和样品通道由于在nanotraps的表面张力。一旦捕获，装在胎圈输送通道迅速胶体粒子和形成在?…
Offenlegungen
The authors have nothing to disclose.
Acknowledgements
这项工作是由美国国立卫生研究院R21 EB008177-01A2和纽约大学阿布扎比（NYUAD）加强研究2013年基金微细加工，我们在表示感谢MIT的MTL的鼎力支持技术人员和詹姆斯·韦斯顿和NYUAD的尼古拉Giakoumidis他们的支持支持采取SEM照片分别建立一个分压器。在PDMS的设备制造在NYUAD的微细核心设施进行。最后，我们想从NYUAD中心感谢丽贝卡Pittam为视频拍摄和编辑数字奖学金。
Materials
| Poly(Styrenesulfonic Acid) Sodium Salt | Polysciences | 08772 | |
| Poly(allylamine) Solution | Sigma Aldrich | 479144-5G | |
| Silica Microsphere – 300 nm | Polysciences | 24321 | |
| Silica Microsphere – 500 nm | Polysciences | 24323 | |
| Silica Microsphere Carboxyl Functional – 500 nm | Polysciences | 24753 | |
| Silica Microsphere Amine Functional – 500 nm | Polysciences | 24756 | |
| Sylgard 184 Silicone Elastomer kit | Dow Corning | ||
| Trichlorosilane | Sigma Aldrich | 175552 | |
| Ultrasonic Cleaner | Branson | 3510 | |
| Tube Rotator | VWR | 10136-084 | |
| Vortex Mixer | WiseMix | VM-10 | |
| Microcentrifuge | VWR | Micro 1207 | |
| Plasma Cleaner | Harrick Plasma | PDC-001-HP | |
| PDMS Mixer | Thinky | ARE-250 | |
| Oven | Thermo Scientific | PR305220M | |
| Epi-fluorescence Microscope | Nikon | Eclipse Ti | |
| CCD Camera | Andor | Clara | |
| Platinum Electrodes | Alfa Aesar | 43014 | |
| Source Meter | Keithley | 2400 | |
| Digital Multimeter | Extech | 410 | |
| Microscopy Glass Slides | Thermo Scientific | 2951-001 | |
| Tween 20 | Merck Millipore | 822184 | |
| Sodium chloride | Fisher Scientific | 7646-14-5 | |
| Sodium phosphate monobasic | Sigma Aldrich | 71505 | |
| Sodium phosphate dibasic | Sigma Aldrich | S3264 | |
| DNA | IDT | CAA CCG ATG CCA CAT CAT TAG CTA C | |
| B-Phycoerythrin | Life Technologies | P-800 | |
| Dynamic light scattering system for Zeta Potential Measurement | Malvern | Zetasizer Nano S | |
| Photoresist | Shipley | SPR700-1.0 | |
| Projection lithography | Nikon | NSR2005i9 | |
| Reactive Ion Etcher | Applied Materials | AME P5000 | |
| ICP deep reactive ion etcher | STS | STS-6" | |
| Contact lithography | Electronic Visions | EV620 | |
| Photoresist Coater Developer | SSI | SSI 150 | |
| Non-contact surface profiler | Wyko | NT 9800 |
Referenzen
- Mawatari, K., Kazoe, Y., Shimizu, H., Pihosh, Y., Kitamori, T. Extended-Nanofluidics: Fundamental Technologies, Unique Liquid Properties, and Application in Chemical and Bio Analysis Methods and Devices. Anal Chem. 86, 4068-4077 (2014).
- Tsukahara, T., Mawatari, K., Kitamori, T. Integrated extended-nano chemical systems on a chip. Chem Soc Rev. 39, 1000-1013 (2010).
- Mani, A., Zangle, T. A., Santiago, J. G. On the Propagation of Concentration Polarization from Microchannel-Nanochannel Interfaces Part I: Analytical Model and Characteristic Analysis. Langmuir. 25, 3898-3908 (2009).
- Aizel, K., et al. Enrichment of nanoparticles and bacteria using electroless and manual actuation modes of a bypass nanofluidic device. Lab Chip. 13, 4476-4485 (2013).
- Wang, Y. C., Stevens, A. L., Han, J. Million-fold preconcentration of proteins and peptides by nanofluidic filter. Anal Chem. 77, 4293-4299 (2005).
- Karnik, R., et al. Electrostatic control of ions and molecules in nanofluidic transistors. Nano letters. 5, 943-948 (2005).
- Mao, P., Han, J. Y. Fabrication and characterization of 20 nm planar nanofluidic channels by glass-glass and glass-silicon bonding. Lab Chip. 5, 837-844 (2005).
- Mao, P., Han, J. Massively-parallel ultra-high-aspect-ratio nanochannels as mesoporous membranes. Lab Chip. 9, 586-591 (2009).
- Balducci, A., Mao, P., Han, J. Y., Doyle, P. S. Double-stranded DNA diffusion in slitlike nanochannels. Macromolecules. 39, 6273-6281 (2006).
- Yamada, M., Mao, P., Fu, J. P., Han, J. Y. Rapid Quantification of Disease-Marker Proteins Using Continuous-Flow Immunoseparation in a Nanosieve Fluidic Device. Anal Chem. 81, 7067-7074 (2009).
- Huh, D., et al. Tuneable elastomeric nanochannels for nanofluidic manipulation. Nat Mater. 6, 424-428 (2007).
- Chung, S., Lee, J. H., Moon, M. W., Han, J., Kamm, R. D. Non-lithographic wrinkle nanochannels for protein preconcentration. Adv Mater. 20, 3011-3016 (2008).
- Park, S. M., Huh, Y. S., Craighead, H. G., Erickson, D. A method for nanofluidic device prototyping using elastomeric collapse. Proc Natl Acad Sci. 106, 15549-15554 (2009).
- Zeng, Y., Harrison, D. J. Self-assembled colloidal arrays as three-dimensional nanofluidic sieves for separation of biomolecules on microchips. Anal Chem. 79, 2289-2295 (2007).
- Malekpourkoupaei, A., Kostiuk, L. W., Harrison, D. J. Fabrication of Binary Opal Lattices in Microfluidic Devices. Chem Mat. 25, 3808-3815 (2013).
- Merlin, A., Salmon, J. -. B., Leng, J. Microfluidic-assisted growth of colloidal crystals. Soft Matter. 8, 3526-3537 (2012).
- Schepelina, O., Zharov, I. PNIPAAM-modified nanoporous colloidal films with positive and negative temperature gating. Langmuir. 23, 12704-12709 (2007).
- Schepelina, O., Zharov, I. Poly(2-(dimethylamino)ethyl methacrylate)-Modified Nanoporous Colloidal Films with pH and Ion Response. Langmuir. 24, 14188-14194 (2008).
- Smith, J. J., Zharov, I. Ion transport in sulfonated nanoporous colloidal films. Langmuir. 24, 2650-2654 (2008).
- Gaspar, A., Hernandez, L., Stevens, S., Gomez, F. A. Electrochromatography in microchips packed with conventional reversed-phase silica particles. Electrophoresis. 29, 1638-1642 (2008).
- Lee, S. Y., et al. High-Fidelity Optofluidic On-Chip Sensors Using Well-Defined Gold Nanowell Crystals. Anal Chem. 83, 9174-9180 (2011).
- Hu, Y. L., et al. Interconnected ordered nanoporous networks of colloidal crystals integrated on a microfluidic chip for highly efficient protein concentration. Electrophoresis. 32, 3424-3430 (2011).
- Zhang, D. -. W., et al. Microfabrication-free fused silica nanofluidic interface for on chip electrokinetic stacking of DNA. Microfluid Nanofluid. 14, 69-76 (2013).
- Syed, A., Mangano, L., Mao, P., Han, J., Song, Y. A. Creating sub-50 nm nanofluidic junctions in a PDMS microchip via self-assembly process of colloidal silica beads for electrokinetic concentration of biomolecules. Lab Chip. 14, 4455-4460 (2014).
- Kim, S. J., Song, Y. A., Han, J. Nanofluidic concentration devices for biomolecules utilizing ion concentration polarization: theory, fabrication, and applications. Chem Soc Rev. 39, 912-922 (2010).
- Fu, J. P., Mao, P., Han, J. Y. Continuous-flow bioseparation using microfabricated anisotropic nanofluidic sieving structures. Nat Protoc. 4, 1681-1698 (2009).
- Plecis, A., Nanteuil, C., Haghiri-Gosnet, A. M., Chen, Y. Electropreconcentration with Charge-Selective Nanochannels. Anal Chem. 80, 9542-9550 (2008).
- Ko, S. H., et al. Nanofluidic preconcentration device in a straight microchannel using ion concentration polarization. Lab Chip. 12, 4472-4482 (2012).
