Models and ultra-sensitive apparatus for electronic single cell analysis

电池是一种动态电子材料，它会随着环境压力的变化而改变电子状态。许多证据表明，细胞的介电变化与重要的生理变化相一致，如干细胞的分化、癌细胞的多药耐药(MDR)和细胞程序性死亡(凋亡)。介电响应的单细胞测量可以识别介电亚群和这些亚群的时间变化，这是普通整体探针不可能做到的。拟议的研究计划将推导出细胞中电子和生理变化之间的关系的量化模型，并生产出具有检测单个细胞中这些介电变化的卓越能力的仪器。这项工作的重点将是在流动系统中使用介电(DEP)，将细胞从储存库带到分析区域，使在合理的时间框架内对大量细胞的分析变得可行。在与G.Bridges的合作中，我开发了一种基于流动的单细胞DEP分析仪器。它可以通过感应细胞内钾浓度下降引起的修正极化来检测细胞凋亡。利用微波干涉仪的差示检测方法，这台DEP细胞仪检测到中国仓鼠卵巢(CHO)细胞的凋亡。*我建议使用众所周知的化合物来研究细胞介电变化的一些基本机制，这些化合物可以抑制或激活特定的生化途径，从而影响细胞的介电特性。例如，哇巴因抑制了细胞中K+Na+泵的运行，导致细胞内离子浓度的变化，从而改变了细胞的介电性质。其他化合物控制允许离子进出细胞的毛孔。这些化合物中的一些也可能被证明是有用的“染料”，提供特定的介电读出。在上面概述的一些生理事件中，这些泵和毛孔被认为发挥了重要作用。这项拟议的研究将测量这些化合物的影响，并推导出将特定过程的抑制与介电变化联系起来的数学模型。电池的体积很小，这使得单电池介电测量非常具有挑战性。将使用新的微波干涉仪设计和DEP驱动方法来降低介质检测下限。这项工作的目标是检测单个电池中低于5%的介电变化(克劳修斯·莫索蒂因数)。*这项跨学科研究计划的HQP将获得许多职业道路的技能。这个小组是为数不多的拥有合作和工具来进行这项研究的小组之一。这项工作将影响体介电体和单细胞介电测量的用户和研究人员，并为单细胞生物生理学提供迫切需要的新工具。

Cells are dynamic electronic materials that change electronic state in response to environmental pressures. There have been many demonstrations that cells exhibit dielectric changes that coincide with important physiological changes such as the differentiation of stem cells, the development of multi drug resistance (MDR) in cancer cells, and programmed cell death (apoptosis). Single cell measurements of the dielectric response can identify dielectric sub-populations and temporal changes to these sub-populations that are not possible with common bulk probes. The proposed research program will derive quantitative models of the relationship between electronic and physiological changes in cells and also to produce instrumentation with superior ability to detect these dielectric changes in single cells. The work will focus on the use of dielectrophoresis (DEP) in a flow system that bring cells from a reservoir to the analysis region, making the analysis of a large number of cells practical in a reasonable time frame. In collaboration with G. Bridges I have developed a flow based single cell DEP analysis instrument. It can detect apoptosis by sensing the modified polarization that results from a drop in intracellular potassium, concentrations. Using a microwave interferometer in a differential detection approach, this DEP cytometer detected apoptosis in Chinese Hamster Ovary (CHO) cells.***I propose to investigate some of the basic mechanisms of dielectric changes in cells using compounds that are well known to inhibit or activate specific biochemical pathways that will impact the dielectric properties of the cell. For example, Ouabain inhibits the operation of the K+Na+ pumps in the cell causing changes to the ion concentrations within the cell and hence its dielectric properties. Other compounds control the pores that allow ions in and out of the cells. Some of these compounds may also prove useful as "dyes" that provide a specific dielectric read out. In some of the physiological events outlined above these pumps and pores have been hypothesized to play a major role. The proposed research will measure the impact of these compounds and derive mathematical models that relate the inhibition of specific processes to dielectric changes. The small volume of cells makes single cell dielectric measurements very challenging. New microwave interferometer designs and DEP actuation methods will be used to lower the dielectric detection limits. The goal of the work is to detect dielectric changes (Clausius Mossotti Factor) of less than 5% in a single cell.***The HQP from this interdisciplinary research program will gain skills for many career paths. This group is one of the few with the collaborations and tools to undertake this research. This work will impact users and researchers of bulk dielectric and single cell dielectric measurements and provide desperately needed new tools for single cell biophysiology.