Measuring electrical and mechanical properties of red blood cells with double optical tweezers

Abstract

Red blood cell (RBC) aggregation in the blood stream is prevented by the zeta potential created by its negatively charged membrane. There are techniques, however, to decrease the zeta potential and allow cell agglutination, which are the basis of most of antigen-antibody tests used in immunohematology. We propose the use of optical tweezers to measure membrane viscosity, adhesion, zeta potential, and the double layer thickness of charges (DLT) formed around the cell in an electrolytic solution. For the membrane viscosity experiment, we trap a bead attached to RBCs and measure the force to slide one RBC over the other as a function of the velocity. Adhesion is quantified by displacing two RBCs apart until disagglutination. The DLT is measured using the force on the bead attached to a single RBC in response to an applied voltage. The zeta potential is obtained by measuring the terminal velocity after releasing the RBC from the trap at the last applied voltage. We believe that the methodology proposed here can provide information about agglutination, help to improve the tests usually performed in transfusion services, and be applied for zeta potential measurements in other samples.

Red blood cell micromanipulation with elliptical laser beam profile optical tweezers in different osmolarity conditions

“…The rotational speed, ω (in rad. s -1 ), is expressed in terms of ξ and the torque, τ, by: It should be noted from figure 3 that the rotation angle increases linearly with the tweezing time, and reaches approximately 6.5 rad at 6 s. From the measured rate of changes of the rotation angle presented in figure 3, the angular velocity and thus the torque τ can be calculated, as a function of time, using the equations (1) and (2). So, in our case, for a red blood cell of 7.5 μm diameter suspended in an isotonic solution of viscosity η≈ 0.7X10 -3 N s m -2 and with a width of r = 2 μm, the rotation speed was found 0.75 rad s -1 (7.32 rpm).…”

“…Optical tweezers have been proved as an efficient tool to induce red blood cells stretching [1,2], deformation and rotation [3,4], for measuring cell properties such as the membrane elasticity, deformability and viscoelasticity. During circulation through capillaries, red blood cells undergo significant physical deformation.…”

Optical tweezers and cell biomechanics in macro- and nano-scale

“…nanoparticles and liposomes). Optical tweezers have also been used as an efficient tool to induce cell stretching 45,46 , deformation and rotation 47,48 and for measuring the relevant cell properties (e.g. elasticity, deformability and viscoelasticity).…”

Experimental Investigation on How Sampling Frequency Affects the Measured Stiffness of an Optical Trap

“…Optical tweezers can be used to directly manipulate colloidal particles, biological cells and metal nano-particles as well as indirectly manipulate macromolecules such as dsDNA, motor flagella protein [2] [3] etc. All these potential applications provide us precious information which benefits us to understand many biochemical and biophysical processes.…”