Enhancing sensitivity and specificity in rare cell capture microdevices with dielectrophoresis

Abstract

The capture and subsequent analysis of rare cells, such as circulating tumor cells from a peripheral blood sample, has the potential to advance our understanding and treatment of a wide range of diseases. There is a particular need for high purity (i.e., high specificity) techniques to isolate these cells, reducing the time and cost required for single-cell genetic analyses by decreasing the number of contaminating cells analyzed. Previous work has shown that antibody-based immunocapture can be combined with dielectrophoresis (DEP) to differentially isolate cancer cells from leukocytes in a characterization device. Here, we build on that work by developing numerical simulations that identify microfluidic obstacle array geometries where DEP-immunocapture can be used to maximize the capture of target rare cells, while minimizing the capture of contaminating cells. We consider geometries with electrodes offset from the array and parallel to the fluid flow, maximizing the magnitude of the resulting electric field at the obstacles' leading and trailing edges, and minimizing it at the obstacles' shoulders. This configuration attracts cells with a positive DEP (pDEP) response to the leading edge, where the shear stress is low and residence time is long, resulting in a high capture probability; although these cells are also repelled from the shoulder region, the high local fluid velocity at the shoulder minimizes the impact on the overall transport and capture. Likewise, cells undergoing negative DEP (nDEP) are repelled from regions of high capture probability and attracted to regions where capture is unlikely. These simulations predict that DEP can be used to reduce the probability of capturing contaminating peripheral blood mononuclear cells (using nDEP) from 0.16 to 0.01 while simultaneously increasing the capture of several pancreatic cancer cell lines from 0.03-0.10 to 0.14-0.55, laying the groundwork for the experimental study of hybrid DEP-immunocapture obstacle array microdevices. V C 2015 AIP Publishing LLC.

Enhanced contactless dielectrophoresis enrichment and isolation platform via cell-scale microstructures

“…Of special interest are cells typically found in small concentrations such as white blood cells, circulating tumor cells and tumor-initiating cells. 1,[11][12][13][14] To separate similar cells, the device must be sensitive enough to distinguish small differences in electrical properties between cells. An example of such separation is the isolation of tumor-initiating cells (TICs), also known as cancer stem cells.…”

Automated electrorotation shows electrokinetic separation of pancreatic cancer cells is robust to acquired chemotherapy resistance, serum starvation, and EMT

“…The robustness of the distinguishing electrical properties to the applied treatments is promising for DEP-enhanced cell capture devices, as proposed in the other work. 17,18,20 Furthermore, these measurements revealed a higher cytoplasmic permittivity than has been previously reported in the literature, which predicts that no upper crossover frequency exists and could be the study of future investigation. Future work could involve studying ROT of cancer cells at higher frequencies to validate this measurement and DEP at higher frequencies to exploit permittivity mismatches to separate cells.…”

“…[17][18][19] Careful device design and frequency selection can attract CTCs while repelling contaminating white blood cells, and simulations have predicted capture efficiency increases of up to 400%. 20 The upper half of Figure 1 shows measured DEP spectra for different white blood cells and cancer cell lines. Differences in the crossover frequency, the frequency in which a cell changes from exhibiting negative to positive DEP, between cancer cells and white blood cells permit positive selection of the rare cancer cells within a blood sample.…”

“…Differences in the crossover frequency between the cancer cells and the white blood cells allow for a positive DEP selection. 15,20,54 because cells are forced to regions in the device where the field is weak, so DEP trapping experiments yield only partial spectra. 21 Additionally, near the crossover frequency, which is of greatest interest for cell separations, the DEP signal is necessarily weakest, making it more vulnerable to confounding effects.…”

Development of three-dimensional integrated microchannel-electrode system to understand the particles' movement with electrokinetics

“…The DEP force exerting on the dielectric particles in non-uniform electric fields is widely used to manipulate the particles. [9][10][11][12][13] Conventionally, in the manipulation technique with electrical method using DEP force, the particles are immersed in low conductivity fluid. However, the low conductivity fluid is not consistent with the natural environment of cells which is highly conductive.…”