Programmable Magnetic Tweezers and Droplet Microfluidic Device for High-Throughput Nanoliter Multi-Step Assays
Programmable Magnetic Tweezers and Droplet Microfluidic Device for High-Throughput Nanoliter Multi-Step Assays
复制标题
DOI：
10.1002/anie.201203862
复制
发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Malaquin, Laurent
中科院分区：
文献类型：
--
作者：
Ali-Cherif, Anais;Begolo, Stefano;Malaquin, Laurent
液滴微流体技术为高通量分析系统的开发提供了独特的能力。[1]它允许将流体等分到纳升或皮升范围内的体积，然后在没有分散或交叉污染的情况下传输任意距离。几个基于液滴的功能，如合并，[2，3]分裂，[2]排序，[2，4]或细胞封装，[3-5]已经被证明。此外，由于它们的“流水线”架构，其中不同的样品沿着同一轨道连续，液滴微流体能够实现具有相对简单的微流体设计的高通量测定，例如，与其中等分通过集成在微流体系统本身中的阀执行的系统相比。[7]不幸的是，从复杂的基质中有效纯化或提取感兴趣的分子的能力，大多数生化方法的关键组成部分，仍然缺乏目前可用于液滴微流体的功能。在宏观方法中，使用超顺磁珠作为固态支持物已经变得非常流行：它们可以结合感兴趣的分析物，在去除上清液时用磁体保留，并在洗脱缓冲液中释放分析物。该过程可以是多路复用的，例如，在微量滴定板的底部使用多个磁体，但它仍然受到显著的限制，特别是由于1）传质限制，2）需要相对大的体积，和3）差的混合和洗涤效率。我们已经提出了一种替代方法，使用微流体格式的自组装磁性微柱。[8，9]以这种方式实现了分析时间的大幅减少和自动化程度的提高，但与其他基于微柱的系统一样，该设备不允许高水平的多路复用，并且不适用于低体积样品处理（小于10 μL）。在这方面，磁性固相萃取与液滴微流体技术的结合很有吸引力。几微升的两个液滴之间的磁珠转移首先由Shikida等人引入。[10]结果是通过永磁体沿着毫米大小的流体通道的位移来实现的，该流体通道将不同的储液器互连。最近提出了一种类似的方法，使用多个润湿阀以允许更复杂的设计，[11]但它仍然需要相当大的体积和孵育时间。为了增加这些测定的灵活性，Sista等人将该策略与通过电润湿（EWOD）在电极阵列上操纵的液滴相结合。[12该装置通常被称为数字微流体装置，非常灵活，但它需要复杂的微制造步骤来将电极阵列集成到装置表面上。还提出了这种方法的一种变体，其中液滴被固定在亲水性贴片上，并且含有磁性颗粒的液滴通过微制造线圈被磁性驱动。[14]然而，液滴尺寸很大（约10 μL），并且系统的微制造几乎与EWOD系统一样苛刻。最近提出了另一种策略，其中含有磁性颗粒的液滴在不对称场的存在下流体动力学地分裂。[15该方法与常规液滴微流体装置共享以每秒数十至数百滴的高通量处理液滴的可能性。然而，即使在单个子液滴中实现了有效的颗粒分离，使用这种方法进行纯化过程也是不有效的，因为上清液的去除是低效的。最近，Gu et al.试图...
Droplet microfluidics offer unique capabilities for the development of high-throughput analytical systems.[1] It allows fluids to be aliquoted into volumes in the nanoliter or picoliter range, and then transported over arbitrary distances without dispersion or cross-contamination. Several droplet-based functions, such as merging,[2, 3] splitting,[2] sorting,[2, 4] or cell encapsulation,[3–5] have already been demonstrated. Moreover, thanks to their “pipeline” architecture, in which different samples follow the same track in a row, droplet microfluidics enable the implementation of high-throughput assays with relatively simple microfluidic designs, as compared for example, to systems in which the aliquoting is performed by valves integrated in the microfluidic system itself.[7] Unfortunately, the ability to efficiently purify or extract molecules of interest from a complex matrix, a key component of most biochemical methods, is still missing from the functions currently available for droplet microfluidics. In macroscopic methods, the use of superparamagnetic beads as a solid state support has become very popular: they can bind an analyte of interest, be retained with a magnet while the supernatant fluid is removed, and release the analyte in an elution buffer. This process can be multiplexed, for example, using multiple magnets at the bottom of microtiter plates, but it still suffers from significant constraints, notably owing to 1) mass transfer limitations, 2) the need for relatively large volumes, and 3) poor mixing and washing efficiencies. We already proposed an alternative approach, using selfassembled magnetic microcolumns in microfluidic format.[8, 9] A large reduction in analysis time and increased automation was achieved in this way, but as with other microcolumnbased systems, this device does not allow for a high level of multiplexing and is not adapted to low-volume sample handling (that is less than 10 μL). In this respect, the combination of magnetic solid-phase extraction with droplet microfluidics is appealing. Magnetic-bead transfer between two droplets of several microliters was first introduced by Shikida et al.[10] Results were achieved by the displacement of a permanent magnet along a millimeter-sized fluidic channel, interconnecting different reservoirs. A similar method, using multiple wetting valves to allow for more complex designs, was recently presented,[11] but it still requires rather large volumes and incubation times. To increase the flexibility of these assays, Sista et al. combined this strategy with droplets manipulated on an array of electrodes by electrowetting (EWOD).[12, 13] This device, generally named a digital microfluidic device, is very flexible, but it requires complex microfabrication steps to integrate the array of electrodes onto the device surface. A variant of this method, in which drops are immobilized on hydrophilic patches and droplets containing magnetic particles are magnetically actuated through microfabricated coils, was also proposed.[14] The drop size, however, is large (approximately 10 μL) and microfabrication of the system is almost as demanding as that of the EWOD systems. Another strategy was proposed recently, in which droplets containing magnetic particles are hydrodynamically split in the presence of an asymmetric field.[15, 16] This approach shares with conventional droplet microfluidic devices the possibility of processing droplets at a high throughput of tens to hundreds of drops per second. However, even if effective particle separation in a single daughter droplet is achieved, using this method for a purification process is not efficient, since the removal of the supernatant fluid is inefficient. More recently, Gu et al. attempted to …