Dynamic Analysis of Drug-Induced Cytotoxicity Using Chip-Based Dielectrophoretic Cell Immobilization Technology

Abstract

Quantification of programmed and accidental cell death provides useful end-points for the anticancer drug efficacy assessment. Cell death is, however, a stochastic process. Therefore, the opportunity to dynamically quantify individual cellular states is advantageous over the commonly employed static, end-point assays. In this work, we describe the development and application of a microfabricated, dielectrophoretic (DEP) cell immobilization platform for the real-time analysis of cancer drug-induced cytotoxicity. Microelectrode arrays were designed to generate weak electro-thermal vortices that support efficient drug mixing and rapid cell immobilization at the delta-shape regions of strong electric field formed between the opposite microelectrodes. We applied this technology to the dynamic analysis of hematopoietic tumor cells that represent a particular challenge for real-time imaging due to their dislodgement during image acquisition. The present study was designed to provide a comprehensive mechanistic rationale for accelerated cell-based assays on DEP chips using real-time labeling with cell permeability markers. In this context, we provide data on the complex behavior of viable vs dying cells in the DEP fields and probe the effects of DEP fields upon cell responses to anticancer drugs and overall bioassay performance. Results indicate that simple DEP cell immobilization technology can be readily applied for the dynamic analysis of investigational drugs in hematopoietic cancer cells. This ability is of particular importance in studying the outcome of patient derived cancer cells, when exposed to therapeutic drugs, as these cells are often rare and difficult to collect, purify and immobilize.

The electrochemical growth of conducting polymer “nanowires”

“…The momentum equation consists of five terms; corresponding to the convective acceleration, pressure gradient, and viscous force inside the medium, and two source terms corresponding to electro-hydrodynamic and electro-convective forces [45,46]:…”

Controlled Rotation and Vibration of Patterned Cell Clusters Using Dielectrophoresis

“…The viability of cells was examined after each experiment, including the experiments carried out for 45 min by on-chip PI staining of cells. 28 No significant difference was observed between the viability of the control (BSA-treated cells, without DEP) and dynamic (BSA-treated cells, with DEP) samples, as shown in Figure S2. The application of a lowamplitude, high-frequency sinusoidal AC signal minimized the cell damage associated with Joule heating of the medium and the effects of inducing transmembrane potential.…”

A Numerical Approach for Dielectrophoretic Characterization and Separation of Human Hematopoietic Cells

“…Therefore, our model might be improved further to provide more realistic cellular dielectric models. The more accurate and precise cellular data gained, the smarter DEP devices and experimental conditions might be 2.8 [27] 3.29 [28] 3.29 [28] 7 [29] Membrane thickness (d, nm) 4.5 [25] 7.5 [30] 7.5 [30] 7 [29] Medium conductivity (σm, S/m) 5.6x 10 -5 [32] 1x10 -6 [33] Membrane permittivity (ℇmem, F/m) 4.44ℇ0 [31] 8.89ℇ0 [28] 10.67ℇ0 [28] 12.5ℇ0 [29] Cytoplasm conductivity (σint, S/m) 0.31 [31] 0.65 [28] 0.73 [28] 0.5 [29] Cytoplasm permittivity (ℇint, F/m) 59ℇ0 [31] 103.9ℇ0 [28] 154.4ℇ0 [28] 50ℇ0 [29] Measured surface area of the cells (A, µm 2 ) --265 [34] 280 [35] Membrane folding factor (Ф) 1 [27] 1.22 [36] 1.94 0.45 designed. Thus, complex biological interactions might be uncovered and applied to precision medicine in the near future.…”