Micropipette suction for measuring piconewton forces of adhesion and tether formation from neutrophil membranes

A new method for measuring piconewton-scale forces that employs micropipette suction is presented here. Spherical cells or beads are used directly as force transducers, and forces as small as 10–20 pN can be imposed. When the transducer is stationary in the pipette, the force is simply the product o...

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Bibliographic Details
Published in:Biophysical journal 1996-11, Vol.71 (5), p.2892-2901
Main Authors: Shao, J.Y., Hochmuth, R.M.
Format: Article
Language:English
Subjects:
Biophysical Phenomena
Biophysics
Cell Adhesion
Cell Membrane - physiology
Humans
Mathematics
Microvilli - physiology
Models, Biological
Neutrophils - cytology
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Summary:A new method for measuring piconewton-scale forces that employs micropipette suction is presented here. Spherical cells or beads are used directly as force transducers, and forces as small as 10–20 pN can be imposed. When the transducer is stationary in the pipette, the force is simply the product of the suction pressure and the cross-sectional area of the pipette minus a small correction for the narrow gap that exists between the transducer and the pipette wall. When the transducer is moving along the pipette, the force on it is corrected by a factor that is proportional to the ratio of its velocity relative to its drag-free velocity. With this technique, the minimum force required to form a membrane tether from neutrophils is determined (45 pN), and the length of the microvilli on the surface of neutrophils is inferred. The strength of this technique is in its simplicity and its ability to measure forces between cells without requiring a separate theory or a calibration against an external standard and without requiring the use of a solid surface.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(96)79486-9