Red blood cell rheology using single controlled laser-induced cavitation bubbles

Abstract

The deformability of red blood cells (RBCs) is an important property that allows the cells to squeeze through small capillary vessels and can be used as an indicator for disease. We present a microfluidic based technique to quantify the deformability of RBCs by stretching a collection of RBCs on a timescale of tens of microseconds in a microfluidic chamber. This confinement constrains the motion of the cell to the imaging plane of the microscope during a transient cavitation bubble event generated with a focused and pulsed laser. We record and analyze the shape recovery of the cells with a high-speed camera and obtain a power law in time, consistent with other dynamic rheological results of RBCs. The extracted exponents are used to characterize the elastic properties of the cells. We obtain statistically significant differences of the exponents between populations of untreated RBCs and RBCs treated with two different reagents: neuraminidase reduces the cell rigidity, while wheat germ agglutinin stiffens the cell confirming previous experiments. This cavitation based technique is a candidate for high-throughput screening of elastic cell properties because many cells can be probed simultaneously in situ, thus with no pre-treatment.

Shearing flow from transient bubble oscillations in narrow gaps

“…This was indeed observed for red blood cells in previous experimental studies using a microfluidic gap [6,7]. Red blood cells are thin, bi-concave cells with a diameter of about 8 µm and a thickness of less than 2 µm.…”

“…These bubbles can be generated with a focused laser pulse [1][2][3], acoustically excited capillary waves [4], or through spark discharges [5]. Applications of these transient pulsating flows span cell stretching [6,7], liquid pumping [8], switching and sorting [9,10], mixing [11], and droplet generation [12].…”

Characterization of periodic cavitation in optical tweezers

“…These bubbles have been used in many different applications where fast actuation of liquid or where impulsive forces are required at a microscopic length scale. For example, in high speed microfluidics [2] and micro-pumps [3], cell membrane permeabilization [4,5] and cell lysis [6], red blood cell stretching and poration [7,8], malaria detection [9], bending of carbon nanotubes and nanowires [10,11].…”

Cell membrane deformation and bioeffects produced by tandem bubble-induced jetting flow

“…The unique combination of high strain rate and large deformation of a cell produced by impulsive stretches from bubble oscillation (10,19) presents a significant challenge to understanding the mechanism of action. Although cell mechanics have been extensively investigated under quasi-static and dynamic loading conditions with low strain rates (20,21), recent evidence suggests that the classical area strain threshold under quasi-static loading conditions (about 3%; ref.…”