Dynamic Light Scattering from Oriented, Rotating Particles: A Theoretical Study and Comparison to Electrorotation Data

Eppmann, Peter; Gimsa, Jan; Prüger, Bernhard; Donath, Edwin

doi:10.1051/jp3:1996131

Cited by 11 publications

(11 citation statements)

References 1 publication

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“…It allows the simultaneous registration of the individual movement of many particles within a population and proved the general advantage of dynamic light scattering (DLS) methods for dielectric particle characterization. For ERLS a homodyne DLS setup was used (Eppmann et al, 1996;Pruger et al, 1997). For the measurement of particle translations induced by dielectrophoresis or TW dielectrophoresis, light scattering methods should also be advantageous.…”

Section: Introductionmentioning

confidence: 99%

Introducing phase analysis light scattering for dielectric characterization: measurement of traveling-wave pumping

Gimsa¹,

Eppmann²,

Prüger³

1997

Biophysical Journal

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Phase analysis light scattering (PALS) was applied to characterize a high-frequency traveling-wave (TW) micropump. Field strength and frequency characteristics were measured for aqueous solutions up to 40 MHz and conductivities of 16 mS/m. The TW field was generated by an ultramicroelectrode array of intercastellated electrodes, which were driven by square-topped signals. Pumping exhibited one major relaxation peak, which strongly increased for conductivities above 4 mS/m. The conductivity dependence of the peak frequency showed an unexpected nonlinear behavior. Around 20 MHz an additional peak caused by electronic resonance was found. Additional coils or capacitors shifted the resonance peak and allowed us to determine the electronic properties of the array. Analysis of distortions in the pump spectra caused by the harmonic content of the driving signals showed that the pump direction is determined by the traveling direction of the field. For measurement of AC-field-induced particle translations, the advantage of PALS over the commonly used microscopic analysis is that it offers an objective method for statistically significant, computerized registration of extremely slow motions. Thus, for dielectric characterization, low field strengths can be used, which is advantageous not only for analyzing liquid pumping, but also for measuring particle translations induced by dielectrophoresis or TW dielectrophoresis.

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Section: Introductionmentioning

confidence: 99%

Introducing phase analysis light scattering for dielectric characterization: measurement of traveling-wave pumping

Gimsa¹,

Eppmann²,

Prüger³

1997

Biophysical Journal

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“…From the ROT spectrum four dielectric parameters can be derived: specific membrane capacity and conductivity (which reflect membrane thickness, composition, morphologic complexity, and the transport of charge carriers across the membrane) and cell internal conductivity and permittivity (reflecting the electrical mobility of ion species and the combined properties of cytoplasmic water and intracellular barriers to charge movement, respectively). These dielectric properties are derived qualitatively from changes of magnitude and frequency of the antifield and co-field peaks as compared to theoretical curves (18,27,28,34).…”

Section: Methodsmentioning

confidence: 99%

Dielectric Changes in Membrane Properties and Cell Interiors of Human Mesothelial Cells in Vitro after Crocidolite Asbestos Exposure

Dopp¹,

Jonas²,

Nebe³

et al. 2000

Environmental Health Perspectives

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Asbestos induces cytogenetic and genotoxic effects in cultured cell lines in vitro. For fiuther investigations of the fiber-induced cellular changes, electrorotation (ROT) measurements can be used to determine early changes of surface properties and dielectric cellular changes. In the present study, human mesothelial cells (HMC) were exosed to nontoxic concentrations of crocidolite asbestos (1 pg/cm2) for 12, 24, 30, 50, and 72 hr, and were investigated for changes in dielectric properties, morphologic and biochemical changs using ROT measurements, electron microscopy, and flow cytometry, respectively. The results of ROT measurements raled slighdy increased internal conductivity and decreased membrane conductance ofHMC during the first 12 hr of exposure to crocidolite. This may be due to functional changes of ion channels of the cellular membrane. However, after exposures of. 30 hr, reduced internal conductivity and increasd membrane conductance of HMC occurred. These effects may be caused by permeabilization ofthe cell membrane and the leakage of ions into the surrounding medium. The membrane capacitance of HMC is always decreased during exposure of cells to crocidolite fibers. This decreased membrane capacitance may result from the observed reduction in the number of microvilli and from the shrnkage of cells as observed by electron microscopy and flow cytometry. Changes in composition of the plasma membrane were also observed after the labeling of phosphatidylserines (PS) on the cell surface. These observed changes can be related to apoptotic events. Whereas during the first 50 hr of exposure only a small number of HMC with increased exposure of PS on the cell surface was detected by flow cytometry, the dielectric properties of HMC showed marked changes during this time. Our results show that surface property changes of the cellular membrane of HMC as well as interior dielectric change occur after the exposure ofcells to crocidolite fibers. The observed changes are discussed in terms of complex combined cellular effects after amphibole asbestos exposure. Key words apoptosis, crocidolite, electron microscopy, electrorotation, flow cytometry, phosphatidylserine, plasma membrane.

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“…Zhou et al (1998) applied a masking threshold to the objects detected in consecutive video images before orientation changes were estimated by elliptical moment analysis of the individual objects. Classical dynamic light scattering techniques have been adapted for detecting the ER of cellular or even smaller objects (Eppmann et al 1996, Prüger et al 1997, Gimsa 1999.…”

Section: Introductionmentioning

confidence: 99%

Optical high-resolution analysis of rotational movement: testing circular spatial filter velocimetry (CSFV) with rotating biological cells

Schaeper

Schmidt

Kostbade

et al. 2016

J. Phys. D: Appl. Phys.

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Circular spatial filtering velocimetry (CSFV) was tested during the microscopic registration of the individual rotations of baker's yeast cells. Their frequency-dependent rotation (electrorotation; ER) was induced in rotating electric fields, which were generated in a glass chip chamber with four electrodes (600 μm tip-to-tip distance). The electrodes were driven with sinusoidal quadrature signals of 5 or 8 V PP with frequencies up to 3 MHz. The observed cell rotation was of the order of 1-100 s per revolution. At each measuring frequency, the independent rotations of up to 20 cells were simultaneously recorded with a high-speed camera. CSFV was software-implemented using circular spatial filters with harmonic gratings. ER was proportional to the phase shift between the values of the spatial filtering signal of consecutive frames. ER spectra obtained by CSFV from the rotation velocities at different ER-field frequencies agreed well with manual measurements and theoretical spectra. Oscillations in the rotation velocity of a single cell in the elliptically polarized field near an electrode, which were resolved by CSFV, could not be visually discerned. ER step responses after field-on were recorded at 2500 frames per second. Analysis proved the high temporal resolution of CSFV and revealed a largely linear torque-friction relation during the acceleration phase of ER. Future applications of CSFV will allow for the simple and cheap automated high-resolution analysis of rotational movements where mechanical detection has too low a resolution or is not possible, e.g. in polluted environments or for gas and fluid vortices, microscopic objects, etc.

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Dynamic Light Scattering from Oriented, Rotating Particles: A Theoretical Study and Comparison to Electrorotation Data

Cited by 11 publications

References 1 publication

Introducing phase analysis light scattering for dielectric characterization: measurement of traveling-wave pumping

Introducing phase analysis light scattering for dielectric characterization: measurement of traveling-wave pumping

Dielectric Changes in Membrane Properties and Cell Interiors of Human Mesothelial Cells in Vitro after Crocidolite Asbestos Exposure

Optical high-resolution analysis of rotational movement: testing circular spatial filter velocimetry (CSFV) with rotating biological cells

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