Spatially resolved microrheology through a liquid/liquid interface

Sohn, In-Sung; Rajagopalan, Raj; Dogariu, Aristide

doi:10.1016/s0021-9797(03)00728-8

Cited by 17 publications

(23 citation statements)

References 24 publications

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“…On the membrane surface (δΩ m ), the integral Equation (5) takes form of (7) The membrane tension γ in the domain-coupling Equation 4is not known a priory and must be found from additional physical considerations. We have chosen the condition of zero dilatation on membrane as a constraint equation: 22 (8) Replacing the velocity vector v(x) in Equation 8by its integral representation given by Equation 7we obtain: (9) with (10) and 11) (12To generalize the approach the governing equations are non-dimensionalized by using the following characteristic scales: length is scaled by the probe radius R, velocity is scaled by the probe approach velocity U, yielding the time scale for imaging as R/U; the membrane tension γ is scaled by μ 1 U (γ-values observed in experiments 23 vary between 2×10 -6 and 2×10 -5 J/ m 2 which, after scaling, give dimensionless values ranging between 0.2 and 2), the membrane bending rigidity B is scaled by μ 1 UR 2 (experimentally observed values for B are in the range 1×10 -20 -7×10 -19 J 24, 25 yielding the scaled values of 0.4 -28), the membrane mean curvature H is scaled by 1/R, and the Gaussian curvature K is scaled by 1/R 2 .…”

Section: Boundary Integral Formulation and Simulation Methodsmentioning

confidence: 99%

Mechanosensing Using Drag Force for Imaging Soft Biological Membranes

Zarnitsyn

Fedorov

2007

Langmuir

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We investigate physical processes taking place during nanoscale mechanosensing of soft biological membranes in liquid environments. Examples include tapping mode imaging by atomic force microscope (AFM) and microscopy based on the Brownian motion of a nanoparticle in an optical-tweezers-controlled trap. The softness and fluidity of the cellular membrane make it difficult to accurately detect (i.e., image) the shape of the cell using traditional mechanosensing methods. The aim of the reported work is to theoretically evaluate whether the drag force acting on the nanoscale mechanical probe due to a combined effect of intra- and extracellular environments can be exploited to develop a new imaging mode suitable for soft cellular interfaces. We approach this problem by rigorous modeling of the fluid mechanics of a complex viscoelastic biosystem in which the probe sensing process is intimately coupled to the membrane biomechanics. The effects of the probe dimensions and elastic properties of the membrane as well as intra- and extracellular viscosities are investigated in detail to establish the structure and evolution of the fluid field as well as the dynamics of membrane deformation. The results of numerical simulations, supported by predictions of the scaling analysis of forces acting on the probe, suggest that viscous drag is the dominant force dictating the probe dynamics as it approaches a biological interface. The increase in the drag force is shown to be measurable, to scale linearly with an increase in the viscosity ratio of the fluids on either side of the membrane, and to be inversely proportional to the probe-to-membrane distance. This leads to the postulation of a new strategy for lipid membrane imaging by AFM or other mechanosensing methods using a variation in the maximum drag force as an indicator of the membrane position.

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Section: Boundary Integral Formulation and Simulation Methodsmentioning

confidence: 99%

Mechanosensing Using Drag Force for Imaging Soft Biological Membranes

Zarnitsyn

Fedorov

2007

Langmuir

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“…Depending on the value of this coefficient, the diffusion is classified as normal for α = 1, and as sub-or super-diffusion for α < 1 and α > 1, respectively [20,21]. Importantly, the effective parameter α determines the asymptotic PSD: ( ) = ℑ − ⟨∆ ( )⟩ ~ ( ) [22,23]. Thus, in the case of whole blood where the erythrocytes are the diffusing probes, the shape of P(f) depends on the viscoelasticity of the complex fluid consisting of plasma and macromolecules.…”

Section: Lc-dls Techniquementioning

confidence: 99%

Passive Coagulability Assay Based on Coherence-Gated Light Scattering

Batarseh

Guzmán-Sepúlveda

et al. 2020

Hemato

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Coagulation monitoring relies on in vitro tests where the clot formation is induced using external stimuli. We report an optical method capable of revealing the propensity of coagulation based solely on the natural dynamics of erythrocytes in whole blood. In contrast to traditional techniques, our approach provides means to assess the blood coagulability without the need to chemically trigger the coagulation. Results of correlations with standard clinical methods suggest that this optical assay could be used for continuous management of blood coagulation during clinical procedures.

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“…This procedure permits isolating the single-scattering component even in optically dense media. 31,32 The temporal uctuations of the intensity resulting from the optical mixing between the back-scattered eld and the reference eld provided by the reection at the end facet of the ber probe are analyzed directly in the frequency domain. It has been shown that, in a range of complex uids, the associated power spectrum of the intensity uctuations can be represented as a superposition of multiple Lorentzian spectra 31,32 Pð…”

Section: Low-coherence Dynamic Light Scatteringmentioning

confidence: 99%