Magnetic tweezers for intracellular applications

Hosu, Basarab Gabriel; Jakab, Károly; Bánki, P.; Tóth, Ferenc; Forgács, Gabor

doi:10.1063/1.1599066

Cited by 119 publications

(78 citation statements)

References 26 publications

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“…Beads, having density of 1.5 g cm −3 , slowly descended on the coverslip and those that landed on cells, adhered to them. Beads typically were in contact with cells for 1 min prior to the application of the magnetic force (for details on the magnetic tweezers, in particular its calibration, see [43]). Experiments were conducted at room temperature.…”

Section: Tether Extraction With Magnetic Tweezersmentioning

confidence: 99%

“…Immediately prior to an experiment, a cell-plated triangular coverslip (fabricated by cutting 18 mm square coverslips (Corning Inc., Corning, NY)) was transferred into a removable sample holder, which fits between the two poles of the MTW, mounted on the stage of an Olympus IX70 inverted microscope (as described in [43]), Cells were first covered with about 200 µl of CO 2 independent medium to which subsequently 10 µl of the bead suspension was added. Beads, having density of 1.5 g cm −3 , slowly descended on the coverslip and those that landed on cells, adhered to them.…”

Section: Tether Extraction With Magnetic Tweezersmentioning

confidence: 99%

“…As presented below, both objectives were possible to reach by employing magnetic tweezers (MTW). The two techniques, AFM (for reviews see [41,42]) and MTW (for a review see [43]) have overlapping but also complementary capabilities. The AFM draws tethers at constant velocity (AFM tethers in what follows), whereas the MTW does it at constant force (MTW tethers in what follows).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Eukaryotic membrane tethers revisited using magnetic tweezers

et al. 2007

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Membrane nanotubes, under physiological conditions, typically form en masse. We employed magnetic tweezers (MTW) to extract tethers from human brain tumor cells and compared their biophysical properties with tethers extracted after disruption of the cytoskeleton and from a strongly differing cell type, Chinese hamster ovary cells. In this method, the constant force produced with the MTW is transduced to cells through super-paramagnetic beads attached to the cell membrane. Multiple sudden jumps in bead velocity were manifest in the recorded bead displacement-time profiles. These discrete events were interpreted as successive ruptures of individual tethers. Observation with scanning electron microscopy supported the simultaneous existence of multiple tethers. The physical characteristics, in particular, the number and viscoelastic properties of the extracted tethers were determined from the analytic fit to bead trajectories, provided by a standard model of viscoelasticity. Comparison of tethers formed with MTW and atomic force microscopy (AFM), a technique where the cantilever-force transducer is moved at constant velocity, revealed significant differences in the two methods of tether formation. Our findings imply that extreme care must be used to interpret the outcome of tether pulling experiments performed with single molecular techniques (MTW, AFM, optical tweezers, etc). First, the different methods may be testing distinct membrane structures with distinct properties. Second, as soon as a true cell membrane (as opposed to that of a vesicle) can attach to a substrate, upon pulling on it, multiple nonspecific membrane tethers may be generated. Therefore, under physiological conditions, distinguishing between tethers formed through specific and nonspecific interactions is highly nontrivial if at all possible.

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Section: Tether Extraction With Magnetic Tweezersmentioning

confidence: 99%

Section: Tether Extraction With Magnetic Tweezersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Eukaryotic membrane tethers revisited using magnetic tweezers

et al. 2007

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“…However, a large number of rising applications do require a careful magnetic characterization of these particles. Magnetic particles are, for example, used as magnetic labels for detection of target molecules in magnetic biosensors, 2,3 for microfluidic applications in lab-on-a-chip systems, 4 for characterization of the mechanical properties of cells, 5 or for measuring biological binding forces. 6 For many applications, nanometer sized particles are becoming increasingly important because of their minimum interference with biological processes.…”

mentioning

confidence: 99%

Confined Brownian motion of individual magnetic nanoparticles on a chip: Characterization of magnetic susceptibility

Ommering

Nieuwenhuis

IJzendoorn

et al. 2006

Applied Physics Letters

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An increasing number of biomedical applications requires detailed knowledge of the magnetic susceptibility of individual particles. With conventional techniques it is very difficult to analyze individual particles smaller than 1μm. The authors demonstrate how the susceptibility of individual nanoparticles can be determined in an efficient way by optically analyzing the confined Brownian motion of a nanoparticle trapped in a known magnetic potential well on a chip. A setup is introduced that has a controllable two-dimensional magnetic potential well, which is defined by an integrated microscopic current wire. Susceptibility measurements have been performed on 150–450nm superparamagnetic beads. They found differences in bead susceptibility of an order of magnitude and differences in volumetric susceptibility of more than a factor of 2.

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“…This is the reason why a lot of techniques to investigate a single microparticle have been developed. [2][3][4][5][6][7] The migration analyses 8 can satisfy this requirement, since the microparticle can be caused to migrate by an extremely weak driving force. For example, only 10 -14 N is enough to move a particle of 1 μm radius at the velocity of 1 μm s -1 , which can be observed by a conventional optical microscope.…”

Section: Introductionmentioning

confidence: 99%

Magnetophoretic Evaluation of Interfacial Adsorption of Dysprosium(III) on a Single Microdroplet

Suwa

Watarai

2008

ANAL. SCI.

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Magnetophoretic velocimetry is a novel technique to measure the magnetic susceptibility of a single microparticle. This techinique could be applied to study the interfacial adsorption equilibria of a paramagnetic dysprosium(III) ion with capric, lauric or stearic acid for a single 2-fluorotoluene microdroplet. The observed magnetic susceptibility of the microorganic droplets was reciprocally proportional to its radius in each case. From the proportional constant, the interfacial concentration of Dy(III) was determined. Furthermore, the dependences of the interfacial concentration on the initial Dy(III) concentration and pH were examined in order to analyze the adsorption equilibrium. Finally, the saturated interfacial concentration and the interfacial adsorption constant at the infinite dilution of Dy(III)-laurate complex were evaluated as 4.8 × 10 -10 mol cm -2 and 3.4 × 10 -2 dm, respectively.

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Magnetic tweezers for intracellular applications

Cited by 119 publications

References 26 publications

Eukaryotic membrane tethers revisited using magnetic tweezers

Eukaryotic membrane tethers revisited using magnetic tweezers

Confined Brownian motion of individual magnetic nanoparticles on a chip: Characterization of magnetic susceptibility

Magnetophoretic Evaluation of Interfacial Adsorption of Dysprosium(III) on a Single Microdroplet

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