Microfluidic systems for DNA extraction, purification and concentration

由于遗传信息可以导致开发有效的疗法来改善人类健康，因此开发用于整个基因组的成本效益测序的方法是重要的。大多数生物分子，如蛋白质和DNA，都带有电荷，并且可以通过电场的作用很容易地在流体中传输，这种现象称为电泳。微流体技术基本上可以将化学工厂缩小到几厘米的规模，并广泛用于基因组测序和绘图。然而，样品仍然必须使用劳动密集型过程来制备，包括化学处理、洗涤和离心的循环。 一个可以通过将DNA与蛋白质和其他细胞碎片分离来制备样品的微流体系统将比目前使用的技术更快、更便宜、更不容易出错。该研究项目将理论和实验研究结合起来，研究在微流体设备中使用电场捕获和分离细胞样本中的DNA所面临的挑战。当聚合物经受剪切流动时，它拉伸并旋转以与流动成一定角度排列。如果然后在与流体流动相反的方向上施加电场，则带电聚合物将垂直于场的轴迁移。这种作用在毛细管的横截面内产生DNA的强烈不均匀分布，并且可以利用它通过适当地调节流动和电场来将DNA捕获在微流体装置内。这种迁移是长的、柔性的和带电的分子所特有的，其中DNA是活细胞中唯一的此类分子。因此，DNA被困在设备内，而其他分子，如蛋白质，则通过。该提案旨在通过使用实验和数值模拟来验证DNA迁移是由电诱导流动驱动的假设，从而更好地理解DNA（或其他DNA）在组合流动和电场中的迁移。该研究将确定在各种条件下交叉流迁移的幅度，以优化用于从全血样品中提取和浓缩DNA的微流体装置的设计。如果能够成功地从裂解物中纯化出DNA，这将是在单一微流控芯片上集成样品制备和分析的重要一步。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Because genetic information can lead to the development of effective therapies to improve human health, it is important to develop methods for the cost-effective sequencing of an entire genome. Most biological molecules, such as proteins and DNA, carry a charge and can be readily transported through fluids by application of an electric field, a phenomenon known as electrophoresis. Microfluidic technologies can essentially miniaturize a chemical factory to the scale of a few centimeters and are widely used for genome sequencing and mapping. However, the samples still must be prepared using a labor-intensive process, involving cycles of chemical treatment, washing and centrifugation. A microfluidic system that could prepare samples by separating the DNA from proteins and other cellular debris would be faster, cheaper, and less error prone than currently used techniques. This research project combines theoretical and experimental investigations into the challenges involved in using electric fields within microfluidic devices to trap and separate DNA from cell samples. When a polymer is subjected to a shear flow, it stretches and rotates to align at an angle to the flow. If an electric field is then applied in the opposite direction to the fluid flow, a charged polymer will migrate perpendicular to the axis of the fields. This action creates a strongly inhomogeneous distribution of DNA within the cross section of a capillary tube, and it can be exploited to trap DNA within a microfluidic device by suitable tuning of the flow and electric fields. This migration is specific to long, flexible, and charged molecules, of which DNA is the only such class of molecules in living cells. Hence, DNA is trapped within the device, while other molecules, such as proteins, pass through. The proposal aims to develop a better understanding of DNA (or other polyelectrolyte) migration in combined flow and electric fields, by using experiments and numerical simulations to validate the hypothesis that polyelectrolyte migration is driven by electrically-induced flows. The research will determine the magnitude of the cross-stream migration under a wide variety of conditions to optimize the design of microfluidic devices for DNA extraction and concentration from samples of whole blood. If DNA can be successfully purified from the lysate, this will be an important step towards integrating sample preparation and analysis on a single microfluidic chip.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.