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A Novel Technique of Quantifying Flexural Stiffness of Rod-Like Structures

Cellular and Molecular Bioengineering volume 1, pages 75–83 (2008)Cite this article

Abstract

In cellular and molecular biomechanics, extensional stiffness of rod-like structures such as leukocyte microvilli can be easily measured with many techniques, but not many techniques are available for measuring their flexural stiffness. In this article, we report a novel technique of measuring the flexural stiffness of rod-like structures. This technique is based on image deconvolution and, as an example, it was used for determining the flexural stiffness of neutrophil microvilli. The probes we used were 40-nm-diameter fluorescent beads, which were bound to the tips of neutrophil microvilli by anti-l-selectin antibody. The fluorescent images of the bead, which was positioned at the center of the cell bottom, were acquired with high magnification and long exposure time (3 s). Using a Gaussian function as the point spread function of our imaging system, we established a convolution equation based on Boltzmann’s law, which yields an analytical expression that relates the bead image profile to the flexural stiffness of the microvillus. The flexural stiffness was then obtained by the least squares regression. On average, the flexural stiffness was determined to be 7 pN/μm for single neutrophil microvilli. With the resolution of our imaging system, this technique can be used for measuring any flexural stiffness smaller than 34 pN/μm and it has great potential in single molecule biomechanics.

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Acknowledgment

This work was supported by the National Institutes of Health (R01 HL069947 and R21/R33 RR017014).

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  1. Department of Biomedical Engineering, Washington University in Saint Louis, 290E Uncas A. Whitaker Hall, Campus Box 1097, One Brookings Drive, Saint Louis, MO, 63130-4899, USA

    Da-Kang Yao & Jin-Yu Shao

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  1. Da-Kang Yao
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  2. Jin-Yu Shao
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Correspondence to Jin-Yu Shao.

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Yao, DK., Shao, JY. A Novel Technique of Quantifying Flexural Stiffness of Rod-Like Structures. Cel. Mol. Bioeng. 1, 75–83 (2008). https://doi.org/10.1007/s12195-008-0012-z

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  • DOI: https://doi.org/10.1007/s12195-008-0012-z

Keywords

  • Biomechanics
  • Microvillus
  • Leukocyte
  • Micropipette
  • Point spread function
  • Deconvolution