Red Blood Cell Magnetophoresis

Abstract

The existence of unpaired electrons in the four heme groups of deoxy and methemoglobin (metHb) gives these species paramagnetic properties as contrasted to the diamagnetic character of oxyhemoglobin. Based on the measured magnetic moments of hemoglobin and its compounds, and on the relatively high hemoglobin concentration of human erythrocytes, we hypothesized that differential migration of these cells was possible if exposed to a high magnetic field. With the development of a new technology, cell tracking velocimetry, we were able to measure the migration velocity of deoxygenated and metHb-containing erythrocytes, exposed to a mean magnetic field of 1.40 T and a mean gradient of 0.131 T/mm, in a process we call cell magnetophoresis. Our results show a similar magnetophoretic mobility of 3.86 x 10(-6) mm(3) s/kg for erythrocytes with 100% deoxygenated hemoglobin and 3.66 x 10(-6) mm(3) s/kg for erythrocytes containing 100% metHb. Oxygenated erythrocytes had a magnetophoretic mobility of from -0.2 x 10(-6) mm(3) s/kg to +0.30 x 10(-6) mm(3) s/kg, indicating a significant diamagnetic component relative to the suspension medium, in agreement with previous studies on the hemoglobin magnetic susceptibility. Magnetophoresis may open up an approach to characterize and separate cells for biochemical analysis based on intrinsic and extrinsic magnetic properties of biological macromolecules.

Continuous separation of blood cells in spiral microfluidic devices

“…These devices solve the issue of trade off which has been faced by earlier microfluidic devices along with providing label-free sorting which has been difficult to achieve especially in case of active devices. [5][6][7][8]37 The considerable reduction in size allows these devices to be integrated with on-chip blood-cell analysis or plasma analysis systems without any sample contamination or sample loss. These passive devices provide both higher sorting efficiency and higher throughput as compared to microfluidic sorting techniques like microfluidic filtration and magnetophoretic devices and hence can be used as a sorting platform for point of care blood-analysis devices.…”

“…Inertial microfluidics takes advantage of hydrodynamic forces that act on cells to focus them within the flow. 5,6,[15][16][17][18][19][20]38 These forces cause cells to migrate across streamlines and order in equilibrium positions based on their size, leading to label-free cell separation, purification, and enrichment in a microfluidic device. Inertial migration was first observed by Segre and Silberberg 39 in 1960s who experimented with neutrally buoyant particles in capillaries and observed a narrow annulus formation at $0.2D from walls of a capillary of diameter D. This migration behavior is believed to be caused by the balance of lift forces arising from the curvature of the parabolic velocity profile (the shear-induced inertial lift) and the interaction between particles and the channel wall (the wall-induced lift).…”

“…5,6,[15][16][17][18][19] We 24,38 and others 16,17,33,38,42 used straight channels to order cells into multiple equilibration positions for size-based separations and flow cytometry. Although straight rectangular channels can be used to sort multiple cell types in single pass, separating more than two cell types causes drastic reduction in sorting efficiency and throughput, especially in high aspect ratio channels.…”

MR phase‐contrast velocity mapping methods for measuring venous blood velocity in the deep veins of the calf

“…3b). The raw-data coverage for each image was split into four interleaved spirals (30), each with a spiral-readout duration of 27.5 ms. Because of initial concerns regarding potential off-resonance distortion due to the magnetic properties of deoxygenated blood (34,35), some preliminary in vivo tests were conducted comparing a range of interleaved spiral designs at similar image resolution and gradient demands. Compared with images acquired using larger numbers of shorter duration spiral interleaves, there was no obvious image blurring in those acquired with four interleaves of 27.5-ms duration (Fig.…”

Continuous-flow ferrohydrodynamic sorting of particles and cells in microfluidic devices

“…Dielectrophoresis (DEP), arising from interactions of cells' dipoles and their surrounding electric fields, can realize low-cost and integrated devices for cell manipulation (Voldman 2006). Magnetophoresis (MAP) takes advantages of paramagnetic nature of red blood cells and magnetotactic bacteria and applies non-uniform magnetic fields to separate them from non-magnetic objects (Zborowski et al 2003; Lee et al 2004). However, most applications of magnetophoresis use functionalized magnetic beads for labeling (Pamme 2006;Liu et al 2009;Gijs et al 2010).…”