Cai Wei, Wang Edward, Chen Ping-Wei, Tsai Yi-Huan, Langouche Lennart, Lo Yu-Hwa
Materials Science and Engineering Program, University of California at San Diego, La Jolla, California 92093, USA.
Chemical Engineering Program, University of California at San Diego, La Jolla, California 92093, USA.
Biomicrofluidics. 2019 Apr 23;13(2):024109. doi: 10.1063/1.5093348. eCollection 2019 Mar.
We present the development of a microfluidic device that is able to selectively and nondisturbingly remove or add components to liquid samples, which allows control and conditioning of the samples for biomedical tests. The device consists of a series of chambers for sample retention and a through channel. Because smaller particles diffuse faster, small particles in the sample such as salt ions rapidly escape the chamber by diffusion and are subsequently removed by a carrier flow in the channel, leaving macromolecules of interest in the "desalted" solution. Conversely, components lacking in the sample can be diffused in by reversing the concentration gradient between the flow and the sample chamber. The ability to control the ionic strength of a sample offers many advantages in biological sample preparation as most biofluids contain high salt contents, making them unsuitable for downstream molecular analyses without additional sample treatments which could cause sample loss, contamination, and cost increase. Making use of the nature of laminar flow in a microfluidic device and mass transport by diffusion, we have developed an analytical model to calculate concentration profiles for different particles. Excellent agreements were found between the theory and the experiment, making the results highly reliable and predictable. Since the device and the principle is applicable to a wide range of biological samples, it can be incorporated into the workflow of various applications for research and diagnosis such as ion exchange, DNA sequencing, immuno assay, vesicle, cell secretion analysis, etc.
我们展示了一种微流控装置的研发成果，该装置能够选择性且无干扰地从液体样品中去除或添加成分，从而能够对用于生物医学测试的样品进行控制和预处理。该装置由一系列用于样品留存的腔室和一条贯通通道组成。由于较小的颗粒扩散得更快，样品中的小颗粒（如盐离子）会通过扩散迅速逸出腔室，随后被通道中的载流带走，从而使感兴趣的大分子留在“脱盐”溶液中。相反，样品中缺乏的成分可以通过逆转流动与样品腔室之间的浓度梯度而扩散进来。控制样品离子强度的能力在生物样品制备中具有诸多优势，因为大多数生物流体含盐量高，若无额外的样品处理，这些生物流体就不适用于下游分子分析，而额外处理可能会导致样品损失、污染以及成本增加。利用微流控装置中层流性质和扩散传质原理，我们开发了一个分析模型来计算不同颗粒的浓度分布。理论与实验结果高度吻合，使得结果具有高度可靠性和可预测性。由于该装置及其原理适用于广泛的生物样品，它可以被纳入各种研究和诊断应用的工作流程中，如离子交换、DNA测序、免疫测定、囊泡、细胞分泌分析等。
