This protocol allows the separation of cancer and healthy cells in a controlled way by keeping the conductivity constant and changing the applied frequency. This protocol simulates the controlled sorting of non-metastatic breast cancer cells and non-tumor breast epithelial cells using AC dielectrophoresis. This technique is the first simulation-based example of inline separation of non-metastatic breast cancer cells and non-tumor breast epithelial cells based on their dielectric properties.
To begin, open the Multiphysics software, select the blank model and right-click on the global definitions. Select parameters and import the parameters given in table one into global definitions as a text file or enter the values individually. Select the Add Component from the home tab and add a 2D component.
Right-click on geometry and import the model file by double-clicking on the file. Choose a blank material and use the material properties from table one. Go to the home tab, select Add Physics and type AC/DC.
Then go to the AC/DC node under the subnode of electric fields and currents and choose electric currents as physics. Insulate the channel walls to assign potential to the electrodes by right-clicking on the electric current and choosing the current conservation, insulate, and electric potential subnodes. Next, select Add Physics from the home tab and under the fluid flow node, go to the subnode single phase flow and choose creeping flow physics.
Right-click on the single phase flow and render the chip boundaries as walls using the wall subnode. Right-click on the single phase flow and add two inlet subnodes and one outlet subnode. Assign the inlets using the inlet subnode and use normal and flow velocity as the boundary condition.
Assign the outlet using the outlet subnode. Then select Add Physics from the home tab and under the fluid flow node, go to the subnode of particle tracing and choose particle tracing flow physics. Right-click on the particle tracing node and check the settings.
Set the particle properties for both MCF-10A and MCF-7 cells using the particle properties subnode. Choose the particle properties from the parameters under the global definition section. Add the drag force subnode to assign the dielectrophoretic force to both types of cells.
In this case, add the particle properties from the parameter section. Now choose Add Mesh and select Fine Mesh from the home tab. For building a mesh, select Build Mesh and click on Add Study to add three study steps.
Study step one is for simulating a frequency response and using a frequency domain subnode. To simulate creeping flow, choose a stationary study node. Add two time-dependent steps to simulate conditions with dielectrophoretic force and without dielectrophoretic force.
For the node dielectrophoretic condition, choose the physics and variable selection, check the modify model configuration box for the study setup and disable the dielectrophoretic step. For dielectrophoretic conditions, do not disable. Run the simulation after saving the file.
After performing the CFD simulations by introducing non-metastatic breast cancer and non-tumor breast epithelial cell lines, solve two sets of CFD studies. For the first set, right-click on study one and add the parametric sweep subnode. Press the plus sign to add fluid medium conductivity sigma_m as the sweep variable.
Perform a parametric sweep study for the fluid medium conductivity sigma_m ranging from 0.01 to 2.5 Siemens per meter, keeping the applied frequency constant at 800 kilohertz. For the second set, conduct a parametric sweep study by varying the applied AC frequency from 100 kilohertz to 100 megahertz, keeping the conductivity of the fluid medium sigma_m fixed at 0.4 Siemens per meter. Calculate the strength of the dielectrophoresis force exerted on a dielectric spherical particle in a conductive medium using this equation under the dielectrophoretic force subnode.
Use this equation for a spherical particle under the dielectrophoretic force subnode. For a spherical particle under the dielectrophoretic force subnode, use this equation. Use a modified form of the previous equation to model biological cells such as mammalian cells which are more complex and have a multi-layered structure.
Then solve complex permeability using this equation. Then plot REK as a function of the applied electric field for cancer and healthy cells. Right-click on the results node.
Add the particle evaluation subnode. And in the expression section, type fpt.deff1. K to plot the CM factor for particle one and fpt.deff2.
K for particle two. Under the fluid medium conductivity of 0.01 Siemens per meter and AC frequency of 100 kilohertz, the MCF-10A and MCF-7 cells experience positive dielectrophoresis with a REK value of 0.82 and 0.76. At the conductivity of 0.4 Siemens per meter, MCF-10A and MCF-7 showed negative dielectrophoretic behavior with REK values of minus 0.46 and minus 0.31 respectively.
When the conductivity was increased to 1.2 Siemens per meter, the cell lines experienced negative dielectrophoresis at 100 kilohertz with REK values minus 0.49 and minus 0.43. Under the conductivity of 0.01 Siemens per meter, both cell types experienced positive dielectrophoresis, moved toward the region of high electric field strength and moved out from the top outlet. MCF-10A cells moved to the top outlet, while MCF-7 cells moved to the bottom outlet when the conductivity was increased to 0.4 Siemens per meter with the applied frequency fixed at 0.8 megahertz.
As the medium conductivity was increased to 1.2 Siemens per meter, the cell lines moved away from the regions of high electric field. At 100 kilohertz frequency, both the cell lines experienced negative dielectrophoresis and moved toward the bottom outlet. The behavior of both cell lines remained unchanged until 0.8 megahertz.
Beyond that, MCF-10A changed their dielectrophoretic behavior and crossed over to the positive dielectrophoretic region. At 100 megahertz, both the cell lines experienced positive dielectrophoretic and moved toward the top outlet. These techniques will open new venues for researchers who want to separate viable and non-viable cells and sort different types of cancer cells if the dielectric properties are not the same.
Also, sorting based on different sizes can be achieved using the same method.
