Age-Dependent Acoustic and Microelastic Properties of Red Blood Cells Determined by Vector Contrast Acoustic Microscopy

Mohamed, Esam T. Ahmed; Kamanyi, Albert E.; Pluta, M.; Grill, Wolfgang

doi:10.1017/s143192761200030x

Cited by 12 publications

(5 citation statements)

References 59 publications

(80 reference statements)

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“…A mesh size of 0.05 mm was used. A density of 1100 kg/m 3 (25,26) and a sound speed of 1650 m/s, similar to the sound speed measured in previous studies (27,28), were used as input parameters. The model was initiated with the RBC at a pressure higher than that of the surrounding fluid to simulate the thermoelastic expansion that occurs immediately after absorption of energy.…”

Section: Methodsmentioning

confidence: 99%

Probing Red Blood Cell Morphology Using High-Frequency Photoacoustics

Strohm

Berndl

Kolios

2013

Biophysical Journal

128

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A method that can rapidly quantify variations in the morphology of single red blood cells (RBCs) using light and sound is presented. When irradiated with a laser pulse, an RBC absorbs the optical energy and emits an ultrasonic pressure wave called a photoacoustic wave. The power spectrum of the resulting photoacoustic wave contains distinctive features that can be used to identify the RBC size and morphology. When particles 5-10 μm in diameter (such as RBCs) are probed with high-frequency photoacoustics, unique periodically varying minima and maxima occur throughout the photoacoustic signal power spectrum at frequencies >100 MHz. The location and distance between spectral minima scale with the size and morphology of the RBC; these shifts can be used to quantify small changes in the morphology of RBCs. Morphological deviations from the normal biconcave RBC shape are commonly associated with disease or infection. Using a single wide-bandwidth transducer sensitive to frequencies between 100 and 500 MHz, we were able to differentiate healthy RBCs from irregularly shaped RBCs (such as echinocytes, spherocytes, and swollen RBCs) with high confidence using a sample size of just 21 RBCs. As each measurement takes only seconds, these methods could eventually be translated to an automated device for rapid characterization of RBC morphology and deployed in a clinical setting to help diagnose RBC pathology.

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Section: Methodsmentioning

confidence: 99%

Probing Red Blood Cell Morphology Using High-Frequency Photoacoustics

Strohm

Berndl

Kolios

2013

Biophysical Journal

128

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“…The RBC geometry is shown in figure 3(d). The sound speed used in the model was 1650 m s −1 (similar to other sound speeds measured (Dukhin et al 2006, Mohamed et al 2012) and the density was 1100 kg m −3 (Godin et al 2007, Grover et al 2011. The blood cell interior was assumed to be homogeneous throughout, both optically and acoustically.…”

Section: The Finite Element Modelmentioning

confidence: 99%

Modeling photoacoustic spectral features of micron-sized particles

et al. 2014

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The photoacoustic signal generated from particles when irradiated by light is determined by attributes of the particle such as the size, speed of sound, morphology and the optical absorption coefficient. Unique features such as periodically varying minima and maxima are observed throughout the photoacoustic signal power spectrum, where the periodicity depends on these physical attributes. The frequency content of the photoacoustic signals can be used to obtain the physical attributes of unknown particles by comparison to analytical solutions of homogeneous symmetric geometric structures, such as spheres. However, analytical solutions do not exist for irregularly shaped particles, inhomogeneous particles or particles near structures. A finite element model (FEM) was used to simulate photoacoustic wave propagation from four different particle configurations: a homogeneous particle suspended in water, a homogeneous particle on a reflecting boundary, an inhomogeneous particle with an absorbing shell and non-absorbing core, and an irregularly shaped particle such as a red blood cell. Biocompatible perfluorocarbon droplets, 3-5 μm in diameter containing optically absorbing nanoparticles were used as the representative ideal particles, as they are spherical, homogeneous, optically translucent, and have known physical properties. The photoacoustic spectrum of micron-sized single droplets in suspension and on a reflecting boundary were measured over the frequency range of 100-500 MHz and compared directly to analytical models and the FEM. Good agreement between the analytical model, FEM and measured values were observed for a droplet in suspension, where the spectral minima agreed to within a 3.3 MHz standard deviation. For a droplet on a reflecting boundary, spectral features were correctly reproduced using the FEM but not the analytical model. The photoacoustic spectra from other common particle configurations such as particle with an absorbing shell and a biconcave-shaped red blood cell were also investigated, where unique features in the power spectrum could be used to identify them.

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“…Increased acoustic attenuation by aged red blood cells also supports an increased hemoglobin concentration and cytosol viscosity. 27 Direct measurements of the relaxation of cellular deformation show that older cells relax more slowly, 28 with a few aged cells relaxing at only onetenth the rate of the mean. 29 We focus on cytosol viscosity, neglecting membrane viscosity, because the large change in viscosity seems to be associated primarily with the cytosol.…”

Section: Introductionmentioning

confidence: 99%

The flow of red blood cells through a narrow spleen-like slit

Freund

2013

Physics of Fluids

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Small slits between endothelial cells in the spleen are perhaps the smallest blood passages in the body, and red blood cells must deform significantly to pass through them. These slits have been posited to participate in the removal of senescent blood cells from the circulation, a key function of the spleen. One of the effects of red blood cell aging is an increased cytosol viscosity; relaxation time measurements suggest their interior viscosity can increase by up to a factor of 10 toward the end of their normal 120 day circulating lifetime. We employ a boundary integral model to simulate red blood cells as they deform sufficiently to flow through such a small passage, whether in the spleen or in a microfluidic device. Different flow rates and cytosol viscosities show three distinct behaviors. (1) For sufficiently slow flow, the pressure gradient is insufficient to overcome elastic resistance and the cell becomes jammed. (2) For faster flow, the cell passes the slit, though more slowly for higher cytosol viscosity. This can be hypothesized to facilitate recognition of senescent cells. (3) A surprising behavior is observed for high elastic capillary numbers, due either to high velocity or high cytosol viscosity. In this case, the cells infold within the slit, with a finger of low-viscosity plasma pushing deeply into the cell from its upstream side. Such infolding might provide an additional mechanism for jamming, and the sharpness of the resulting features would be expected to promote cell degradation. Linear analysis of a model system shows a similar instability, which is analyzed in regard to the cell flow. This linear analysis also suggests a similar instability for unphysiologically low cytosol viscosity. Simulations confirm that a similar infolding also occurs in this case, which intriguingly suggests that normal cytosol viscosities are in a range that is protective against such deformations.

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Age-Dependent Acoustic and Microelastic Properties of Red Blood Cells Determined by Vector Contrast Acoustic Microscopy

Cited by 12 publications

References 59 publications

Probing Red Blood Cell Morphology Using High-Frequency Photoacoustics

Probing Red Blood Cell Morphology Using High-Frequency Photoacoustics

Modeling photoacoustic spectral features of micron-sized particles

The flow of red blood cells through a narrow spleen-like slit

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