OpenDEP: An Open-Source Platform for Dielectrophoresis Spectra Acquisition and Analysis

Dielectrophoretic (DEP) cell separation, which utilizes electric fields to selectively manipulate and separate cells based on their electrical properties, has emerged as a cutting-edge label-free technique. DEP separation techniques rely on differences in the electrical and morphological properties of cells, which can be obtained by a thorough analysis of DEP spectra. This article presents a novel platform, named OpenDEP, for acquiring and processing DEP spectra of suspended cells. The platform consists of lab-on-a-chip and open-source software that enables the determination of DEP spectra and electric parameters. The performance of OpenDEP was validated by comparing the results obtained using this platform with the results obtained using a commercially available device, 3DEP from DEPtech. The lab-on-a-chip design features two indium tin oxide-coated slides with a specific geometry, forming a chamber where cells are exposed to an inhomogeneous alternating electric field with different frequencies, and microscopic images of cell distributions are acquired. A custom-built software written in the Python programing language was developed to convert the acquired images into DEP spectra, allowing for the estimation of membrane and cytoplasm conductivities and permittivities. The platform was validated using two cell lines, DC3F and NIH 3T3. The OpenDEP platform offers several advantages, including easy manufacturing, statistically robust computations due to large cell population analysis, and a closed environment for sterile work. Furthermore, continuous observation using any microscope allows for integration with other techniques

Changes of cell electrical parameters induced by electroporation. A dielectrophoresis study

AbstractDielectrophoresis was employed to distinguish the electroporated from non-electroporated cells. It was found that the electric field frequency at which cells change the direction of their movement (the crossover frequency fCO) is higher when cells are electroporated. The contribution to the cell dielectrophoretic behavior of four electric and geometrical cell parameters was analyzed using a single shell model. fCO measurements were performed in media with conductivities of 0.001–0.09S/m, on B16F10 cells which were electroporated in a Mannitol solution (0.001S/m), using rectangular or exponential pulses. The control cells' fCO was found in a domain of 2 to 105kHz, while the electroporated cells' fCO was in a domain of 5 to 350kHz, depending on the external media conductivities. At exterior conductivities above ~0.02S/m, fCO of electroporated cells became significantly higher compared to controls. Even though the possible contribution of membrane permittivity to explain the observed fCO shift toward higher values cannot be excluded, the computations highlight the fact that the variation of cytosol conductivity might be the major contributor to the dielectrophoretic behavior change. Our experimental observations can be described by considering a linear dependence of electroporated cells' cytosol conductivity against external conductivity

Dosimetry of an in vitro exposure system for fluorescence measurements during 2.45 GHz microwave exposure

International audienceAn in vitro system for 2.45 GHz microwave (MW) exposure with real-time fluorescence measurements is proposed. This system is specifically designed for the measurement of those biophysical parameters of living cells or membrane models which can be quantified by spectrofluorometric methods (e.g. membrane generalized polarization (GP), membrane fluidity, membrane potential, etc.). The novelty of the system consists in the possibility to perform fluorescence measurements on the biological samples simultaneously with their exposure to MW. The MW applicator is an open ended coaxial antenna which is dipped into a cuvette. The distribution of electromagnetic field and specific absorption rate (SAR) in the cuvette are provided from a rigorous electromagnetic numerical analysis performed with a finite difference-time domain (FDTD) based tool. With this system, fluorescence measurements were used to calculate the membrane GP values of giant unilamellar vesicle suspensions that were acquired during exposure to a 1.2 W incident power. For this power, the SAR distribution and mean SAR value for the whole volume were calculated based on temperature measurements made at different positions inside the cuvette