Calibration Of Optical Tweezers In Viscoelastic Media

Fischer, Mario; Richardson, Andrew C.; Reihani, S. Nader S.; Oddershede, Lene B.; Berg-Sørensen, Kirstine

doi:10.1016/j.bpj.2008.12.3396

Cited by 4 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using a recently developed in vivo calibration technique (Methods) (14,15), we measured the in vivo stall forces of lipid vesicles in A549 human epithelial cells and phagocytosed polystyrene beads in Dictyostelium discoideum. We used these two cell types to compare stall forces with each other.…”

Section: Resultsmentioning

confidence: 99%

“…We used a unique method, called the fluctuation-dissipation theorem (FDT) method (14,15), to calibrate the trap stiffness in vivo. By taking a "passive" and an "active" measurement, we measure the three unknowns in the cellular trapping environment: the local elasticity, the local viscosity, and the trap stiffness.…”

Section: Resultsmentioning

confidence: 99%

“…The passive and active calibration measurements are occurring during and throughout the stall force measurements. This technique has been shown to work in a variety of viscoelastic materials, including actin polymers (15) and hyaluronic acid (Fig. S2).…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

In vivo optical trapping indicates kinesin’s stall force is reduced by dynein during intracellular transport

Blehm

Schroer

Trybus

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

107

View full text Add to dashboard Cite

Kinesin and dynein are fundamental components of intracellular transport, but their interactions when simultaneously present on cargos are unknown. We built an optical trap that can be calibrated in vivo during data acquisition for each individual cargo to measure forces in living cells. Comparing directional stall forces in vivo and in vitro, we found evidence that cytoplasmic dynein is active during minus- and plus-end directed motion, whereas kinesin is only active in the plus direction. In vivo, we found outward (∼plus-end) stall forces range from 2 to 7 pN, which is significantly less than the 5- to 7-pN stall force measured in vitro for single kinesin molecules. In vitro measurements on beads with kinesin-1 and dynein bound revealed a similar distribution, implying that an interaction between opposite polarity motors causes this difference. Finally, inward (∼minus-end) stalls in vivo were 2–3 pN, which is higher than the 1.1-pN stall force of a single dynein, implying multiple active dynein.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

In vivo optical trapping indicates kinesin’s stall force is reduced by dynein during intracellular transport

Blehm

Schroer

Trybus

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

107

View full text Add to dashboard Cite

show abstract

“…Among these, molecular tension sensors based on Förster resonance energy transfer (93)(94)(95), spectral emission changes due to proximity (96), and fluorescence quenching (97) enabled pN-sensitivity measurements of intramolecular tension. Direct manipulation and force measurement in living cells with optical tweezers have also seen great progress recently, thanks to developments in calibration methods taking into account any variations among cargoes and local viscoelastic properties of the cytoplasm (98)(99)(100)(101)(102). All such advancements will be crucial toward providing new insights into the mechanisms of the myriad biological processes that are directly regulated by force or connected to the mechanical conditions in the cell and its surrounding environment.…”

Section: Discussionmentioning

confidence: 98%

Interrogating Biology with Force: Single Molecule High-Resolution Measurements with Optical Tweezers

Capitanio

Pavone

2013

Biophysical Journal

130

108

View full text Add to dashboard Cite

Single molecule force spectroscopy methods, such as optical and magnetic tweezers and atomic force microscopy, have opened up the possibility to study biological processes regulated by force, dynamics of structural conformations of proteins and nucleic acids, and load-dependent kinetics of molecular interactions. Among the various tools available today, optical tweezers have recently seen great progress in terms of spatial resolution, which now allows the measurement of atomic-scale conformational changes, and temporal resolution, which has reached the limit of the microsecond-scale relaxation times of biological molecules bound to a force probe. Here, we review different strategies and experimental configurations recently developed to apply and measure force using optical tweezers. We present the latest progress that has pushed optical tweezers' spatial and temporal resolution down to today's values, discussing the experimental variables and constraints that are influencing measurement resolution and how these can be optimized depending on the biological molecule under study.

show abstract

“…30). Results for the spring constant of the trap, and the effective spring constant felt by the bead, found as the inverse of the absolute value of the response function χ(ω) are displayed in Fig.…”

Section: Methodsmentioning

confidence: 99%

Validation of FDT calibration method in complex media

Fischer

Richardson²,

Reihani

et al. 2008

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

Optical tweezers constitute an obvious choice as the experimental technique for manipulation and trapping of organelles in living cells. For quantitative determination of the forces exerted in such in vivo systems, however, tools for reliable calibration of the optical tweezers are required. This is complicated by the fact that the viscoelastic properties of the cytoplasm are a priori unknown. We elaborate on a previously reported theoretical calibration procedure and verify its authenticity experimentally. With this approach, we may at the same time determine the trapping characteristics of the optical tweezers and the viscoelastic properties of the cytoplasm. The method employs the fluctuation-dissipation theorem (FDT) which is assumed valid for the situations considered. This allows for extracting the requested properties from two types of measurements that we denote as passive and active. In the passive part, the Brownian motion of a particle inside the trap is observed. In the active part, the system is slightly perturbed and the response of the trapped particle is tracked. Gently oscillating the stage on which the sample is mounted allows the delay between the position of the stage and the response of the trapped bead, using a quadrant photodiode, to be quantified. No assumptions about the particle radius or geometry or about the frequency-dependent friction coefficient are needed.The paper contains the theoretical background of the method in terms of convenient formulations of the fluctuation-dissipation theorem and application of the method in two types of experiments. Further we discuss experimental concerns which are i) the choice of driving characteristics in the active part of the calibration procedure and ii) statistical errors.

show abstract

Calibration Of Optical Tweezers In Viscoelastic Media

Cited by 4 publications

References 0 publications

In vivo optical trapping indicates kinesin’s stall force is reduced by dynein during intracellular transport

In vivo optical trapping indicates kinesin’s stall force is reduced by dynein during intracellular transport

Interrogating Biology with Force: Single Molecule High-Resolution Measurements with Optical Tweezers

Validation of FDT calibration method in complex media

Contact Info

Product

Resources

About