Calibration of Optical Tweezers for In Vivo Force Measurements: How do Different Approaches Compare?

Jun, Yonggun; Tripathy, Suvranta K.; Narayanareddy, Babu Reddy Janakaloti; Mattson-Hoss, Michelle K.; Gross, Steven P.

doi:10.1016/j.bpj.2014.07.033

Cited by 101 publications

(71 citation statements)

References 39 publications

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“…The detection QPD’s voltage is recorded and normalized to the sum of the total voltage on the QPD for each dimension (x and y). A high NA condenser collects all scattered light from the bead and the conjugate image of the bead is mapped onto the back-focal plane and collected on the QPD(Farré & Montes-usategui, 2010; Gittes & Schmidt, 1998; Grange, Husale, Güntherodt, & Hegner, 2002; Jun, Tripathy, Narayanareddy, Mattson-hoss, & Gross, 2014). A line fit to the data is used to obtain a volt-to-nanometer conversion in both dimensions (x and y).…”

Section: Optical Trap-based Microrheologymentioning

confidence: 99%

Mechanical Properties of the Tumor Stromal Microenvironment Probed In Vitro and Ex Vivo by In Situ-Calibrated Optical Trap-Based Active Microrheology

et al. 2016

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One of the hallmarks of the malignant transformation of epithelial tissue is the modulation of stromal components of the microenvironment. In particular, aberrant extracellular matrix (ECM) remodeling and stiffening enhances tumor growth and survival and promotes metastasis. Type I collagen is one of the major ECM components. It serves as a scaffold protein in the stroma contributing to the tissue’s mechanical properties, imparting tensile strength and rigidity to tissues such as those of the skin, tendons, and lungs. Here we investigate the effects of intrinsic spatial heterogeneities due to fibrillar architecture, pore size and ligand density on the microscale and bulk mechanical properties of the ECM. Type I collagen hydrogels with topologies tuned by polymerization temperature and concentration to mimic physico-chemical properties of a normal tissue and tumor microenvironment were measured by in situ-calibrated Active Microrheology by Optical Trapping revealing significantly different microscale complex shear moduli at Hz-kHz frequencies and two orders of magnitude of strain amplitude that we compared to data from bulk rheology measurements. Access to higher frequencies enabled observation of transitions from elastic to viscous behavior that occur at ~200Hz to 2750Hz, which largely was dependent on tissue architecture well outside the dynamic range of instrument acquisition possible with SAOS bulk rheology. We determined that mouse melanoma tumors and human breast tumors displayed complex moduli ~5–1000 Pa, increasing with frequency and displaying a nonlinear stress-strain response. Thus, we show the feasibility of a mechanical biopsy in efforts to provide a diagnostic tool to aid in the design of therapeutics complementary to those based on standard histopathology.

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Section: Optical Trap-based Microrheologymentioning

confidence: 99%

Mechanical Properties of the Tumor Stromal Microenvironment Probed In Vitro and Ex Vivo by In Situ-Calibrated Optical Trap-Based Active Microrheology

et al. 2016

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“…The tracking software written by LabVIEW program recorded the motion of the trapped beads and the associated force produced on a real time basis [25]. Each bead was monitored for couple of minutes, and data associated to the force production vs. the time of individual beads were collected.…”

Section: Visualization and Data Analysismentioning

confidence: 99%

The Contribution of the C-Terminal Tails of Microtubules in Altering the Force Production Specifications of Multiple Kinesin-1

Feizabadi

2016

Cell Biochem Biophys

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The extent to which beta tubulin isotypes contribute to the function of microtubules and the microtubule-driven transport of molecular motors is poorly understood. The major differences in these isotypes are associated with the structure of their C-terminal tails. Recent studies have revealed a few aspects of the C-terminal tails' regulatory role on the activities of some of the motor proteins on a single-molecule level. However, little attention is given to the degree to which the function of a team of motor proteins can be altered by the microtubule's tail. In a set of parallel experiments, we investigated this open question by studying the force production of several kinesin-1 (kinesin) molecular motors along two groups of microtubules: regular ones and those microtubules whose C-terminals are cleaved by subtilisin digestion. The results indicate that the difference between the average of the force production of motors along two types of microtubules is statistically significant. The underlying mechanism of such production is substantially different as well. As compared to untreated microtubules, the magnitude of the binding time of several kinesin-1 is almost three times greater along subtilisin-treated microtubules. Also, the velocity of the group of kinesin molecules shows a higher sensitivity to external loads and reduces significantly under higher loads along subtilisin-treated microtubules. Together, this work shows the capacity of the tails in fine-tuning the force production characteristics of several kinesin molecules.

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“…Those kinesin with the proper orientations that could bind to an individual microtubule could create the movement of the trapped beads. This movements were recorded with a custom LabView program [38]. The kinesin-1 coated beads progressed in one direction on a microtubule.…”

Section: Microtubule Bead Visualization and Data Analysismentioning

confidence: 99%

Kinesin-1 translocation: Surprising differences between bovine brain and MCF7-derived microtubules

Feizabadi¹,

Jun²

2014

Biochemical and Biophysical Research Communications

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Calibration of Optical Tweezers for In Vivo Force Measurements: How do Different Approaches Compare?

Cited by 101 publications

References 39 publications

Mechanical Properties of the Tumor Stromal Microenvironment Probed In Vitro and Ex Vivo by In Situ-Calibrated Optical Trap-Based Active Microrheology

Mechanical Properties of the Tumor Stromal Microenvironment Probed In Vitro and Ex Vivo by In Situ-Calibrated Optical Trap-Based Active Microrheology

The Contribution of the C-Terminal Tails of Microtubules in Altering the Force Production Specifications of Multiple Kinesin-1

Kinesin-1 translocation: Surprising differences between bovine brain and MCF7-derived microtubules

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