Wang Fen, Wang Hao, Wang Jun, Wang Hsiang-Yu, Rummel Peter L, Garimella Suresh V, Lu Chang
Department of Agricultural and Biological Engineering, 225 S. University Street, Purdue University, West Lafayette, Indiana 47907, USA.
Biotechnol Bioeng. 2008 May 1;100(1):150-8. doi: 10.1002/bit.21737.
Microfluidics-based cell assays offer high levels of automation and integration, and allow multiple assays to be run in parallel, based on reduced sample volumes. These characteristics make them attractive for studies associated with drug discovery. Controlled delivery of drug molecules or other exogenous materials into cells is a critical issue that needs to be addressed before microfluidics can serve as a viable platform for drug screening and studies. In this study, we report the application of hydrodynamic focusing for controlled delivery of small molecules into cells immobilized on the substrate of a microfluidic device. We delivered calcein AM which was permeant to the cell membrane into cells, and monitored its enzymatic conversion into fluorescent calcein during and after the delivery. Different ratios of the sample flow to the side flow were tested to determine how the conditions of hydrodynamic focusing affected the delivery. A 3D numerical model was developed to help understand the fluid flow, molecular diffusion due to hydrodynamic focusing in the microfluidic channel. The results from the simulation indicated that the calcein AM concentration on the outer surface of a cell was determined by the conditions of hydrodynamic focusing. By comparing the results from the simulation with those from the experiment, we found that the calcein AM concentration on the cell outer surface correlated very well with the amount of the molecules delivered into the cell. This suggests that hydrodynamic focusing provides an effective way for potentially quantitative delivery of exogenous molecules into cells at the single cell or subcellular level. We expect that our technique will pave the way to high-throughput drug screening and delivery on a microfluidic platform.
基于微流控的细胞检测具有高度的自动化和集成性，并且基于减少的样本体积，能够并行进行多种检测。这些特性使其在与药物发现相关的研究中具有吸引力。在微流控能够成为药物筛选和研究的可行平台之前，将药物分子或其他外源物质可控地递送至细胞内是一个需要解决的关键问题。在本研究中，我们报告了利用流体动力聚焦将小分子可控地递送至固定在微流控装置基底上的细胞内的应用。我们将可透过细胞膜的钙黄绿素乙酰甲酯递送至细胞内，并在递送过程中和递送后监测其酶促转化为荧光钙黄绿素的过程。测试了样品流与侧流的不同比例，以确定流体动力聚焦条件如何影响递送。开发了一个三维数值模型，以帮助理解微流控通道中由于流体动力聚焦引起的流体流动和分子扩散。模拟结果表明，细胞外表面的钙黄绿素乙酰甲酯浓度由流体动力聚焦条件决定。通过将模拟结果与实验结果进行比较，我们发现细胞外表面的钙黄绿素乙酰甲酯浓度与递送至细胞内的分子数量非常吻合。这表明流体动力聚焦为在单细胞或亚细胞水平将外源分子潜在地定量递送至细胞内提供了一种有效方法。我们期望我们的技术将为微流控平台上的高通量药物筛选和递送铺平道路。
