Department of Mechanical Engineering, York University, BRG 433B, 4700 Keele St, Toronto, ON M3J 1P3, Canada.
Soft Matter. 2018 Jul 4;14(26):5356-5363. doi: 10.1039/c8sm00162f.
One of the common operations in sample preparation is to separate specific particles (e.g. target cells, embryos or microparticles) from non-target substances (e.g. bacteria) in a fluid and to wash them into clean buffers for further processing like detection (called solution exchange in this paper). For instance, solution exchange is widely needed in preparing fluidic samples for biosensing at the point-of-care and point-of-use, but still conducted via the use of cumbersome and time-consuming off-chip analyte washing and purification techniques. Existing small-scale and handheld active and passive devices for washing particles are often limited to very low throughputs or require external sources of energy. Here, we integrated Dean flow recirculation of two fluids in curved microchannels with selective inertial focusing of target particles to develop a microfluidic centrifuge device that can isolate specific particles (as surrogates for target analytes) from bacteria and wash them into a clean buffer at high throughput and efficiency. We could process micron-size particles at a flow rate of 1 mL min-1 and achieve throughputs higher than 104 particles per second. Our results reveal that the device is capable of singleplex solution exchange of 11 μm and 19 μm particles with efficiencies of 86 ± 2% and 93 ± 0.7%, respectively. A purity of 96 ± 2% was achieved in the duplex experiments where 11 μm particles were isolated from 4 μm particles. Application of our device in biological assays was shown by performing duplex experiments where 11 μm or 19 μm particles were isolated from an Escherichia coli bacterial suspension with purities of 91-98%. We envision that our technique will have applications in point-of-care devices for simultaneous purification and solution exchange of cells and embryos from smaller substances in high-volume suspensions at high throughput and efficiency.
样品制备中的常见操作之一是将特定颗粒（例如靶细胞、胚胎或微粒）从流体中的非靶物质（例如细菌）中分离出来，并将其冲洗到清洁的缓冲液中进行进一步处理，例如检测（在本文中称为溶液交换）。例如，在即时护理和即时使用的生物传感中，广泛需要进行流体样品的溶液交换，但仍然需要通过使用繁琐且耗时的片外分析物洗涤和纯化技术来完成。现有的用于洗涤颗粒的小型手持式主动和被动设备通常限于非常低的吞吐量，或者需要外部能源。在这里，我们将两种流体的迪恩流在弯曲微通道中的再循环与目标颗粒的选择性惯性聚焦集成在一起，开发了一种微流控离心机设备，该设备可以从细菌中分离出特定颗粒（作为靶分析物的替代品），并以高效率和高通量将其冲洗到清洁的缓冲液中。我们可以以 1 mL min-1的流速处理微米级颗粒，并且可以实现超过 104 个颗粒每秒的吞吐量。我们的结果表明，该设备能够以 86±2%和 93±0.7%的效率对 11 μm 和 19 μm 颗粒进行单重溶液交换。在 11 μm 颗粒从 4 μm 颗粒中分离的双重实验中，达到了 96±2%的纯度。通过进行双重实验，从大肠杆菌悬浮液中分离出 11 μm 或 19 μm 颗粒，纯度为 91-98%，证明了该设备在生物测定中的应用。我们设想，我们的技术将在即时护理设备中得到应用，用于从高体积悬浮液中的较小物质中同时纯化和交换细胞和胚胎，具有高通量和高效率。
