A numerical approach for dielectrophoretic characterization and separation of human hematopoietic cells

Rapid and reliable characterization of hematopoietic cells still remain the first step for precise medicine. Diagnosis of various diseases, ranging from infectious to cancer, relies on quantification of hematopoietic cells from blood. Therefore, there is an emerging need for label-free, lowcost, time-efficient, reproducible and quantitative characterization tools for the blood cells. Addressed herein is a numerical analysis for dielectrophoretic characterization of red blood cells, T-lymphocytes, B-lymphocytes and monocytes, which quantitatively incorporate with the membrane features of these cells to provide more insight into their dielectrophoretic responses

Single cell level dielectrophoretic responses & dielectrophoretic deformations of monocytes to quantify population heterogeneity

Single-cell dielectrophoretic movement and dielectrophoretic deformation of monocyte cells were interrogated applying 20 V pp , 50 kHz to 1 MHz signal in the 3D carbon electrode array. Heterogeneity of the monocyte population is shown in terms of the crossover frequencies, translational movement, and deformation index of the cells. The results presented that crossover range for monocytes was 100 kHz - 200 kHz, the translational movement of the cells was rapidly altered when the initial positions of the cells were in the negative dielectrophoretic region. Finally, the deformation index of the monocyte population varied from 0.5 to 1.5

Quantitative investigation for the dielectrophoretic effect of fluorescent dyes at single-cell resolution

Most of the microscopy-based, quantitative assays rely on fluorescent dyes. In this study, we investigated the impact of fluorescent dyes on the dielectrophoretic response of the mammalian cells. The dielectrophoretic measurements were performed to quantify whether the fluorescent dyes alter the dielectrophoretic properties of the cells at single-cell resolution. Our results present that when 10 V-pp electric field is applied, the fluorescent-labeled cells experienced the crossover frequency at 8-10 kHz, whereas the label-free cells exhibited at 16-18 kHz

Dielectrophoretic characterization and separation of leukocytes

Characterization and separation of leukocytes are critical for precision in medical diagnostics, treatment and biomedical research. Existing characterization and separation methods are generally based on centrifugation or antibody-mediated recognition assays. Even though these methods are highly sensitive and specific, they are sometimes inefficient and require several preparative steps involving heavy equipment. Moreover, antibody labeling might cause biases during characterization and change the cell phenotype, particularly for immunological cells that can quickly respond and adapt to environmental changes. Dielectrophoresis (DEP) has a great potential for noninvasive manipulation of cells based on their dielectric characteris­tics. It is a favorable alternative to the current cell manipulation methods by being label-free, low-cost, fast and accurate. In this thesis, dielectrophoretic character­ization of U937 monocytes, macrophages, dead cells and monocytes stained with commercially available fluorescent dyes are presented using a 3D carbon-electrode DEP device. Also, a new DEP model is proposed, and dielectrophoretic character­ization of leukocytes and RBCs were performed using the proposed model. Then, live-dead leukocytes and monocytes-macrophages were separated successfully based on differences between their dielectric properties, while preserving their viability. This approach will reduce the dead cell contamination risk in blood analyses and increase the precision in disease diagnostics by achieving more reliable and accurate test results

Bir müze otel olarak Pera Palas

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2013.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Melike Ünal.Ünal, Melike. HIST 200-1ÜNAL HIST 200-1/2 2012-1

Dielectrophoretic characterization and separation of monocytes and macrophages using 3D carbon-electrodes

Monocyte heterogeneity and its prevalence are revealed as indicator of several human diseases ranking from cardiovascular diseases to rheumatoid arthritis, chronic kidney diseases, autoimmune multiple sclerosis, and stroke injuries. When monocytes and macrophages are characterized and isolated with preserved genetic, phenotypic and functional properties, they can be used as label‐free biomarkers for precise diagnostics and treatment of various diseases. Here, the dielectrophoretic responses of the monocytes and macrophages were examined. We present 3D carbon‐electrode dielectrophoresis (carbon‐DEP) as a separation tool for U937 monocytes and U937 monocyte‐differentiated macrophages. The carbon‐electrodes advanced the usability and throughput of DEP separation, presented wider electrochemical stability. Using the 3D carbon‐DEP chip, we first identified the selective positive and negative DEP responses and specific crossover frequencies of monocytes and macrophages as their signatures for separation. The crossover frequency of monocytes and macrophages was 17 and 30 kHz, respectively. Next, we separated monocyte and macrophage subpopulations using their specific dielectrophoretic responses. Afterward, we used a fluorescence‐activated cell sorter to confirm our results. Finally, we enriched 70% of monocyte cells from the mixed cell population, in other words, concentration of monocyte cells to macrophage cells was five times increased, using the 30‐kHz, 10‐Vpp electric field and 1 μL/min flow rate