Direct measurement of interaction forces between a single bacterium and a flat plate

A technique for precisely measuring the equilibrium and viscous interaction forces between a single bacterium and a flat surface as functions of separation distance is described. A single-beam gradient optical trap was used to micromanipulate the bacterium against a flat surface while evanescent wav...

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Bibliographic Details
Published in:Journal of colloid and interface science 2003-05, Vol.261 (2), p.379-385
Main Authors: Klein, Jonah D, Clapp, Aaron R, Dickinson, Richard B
Format: Article
Language:English
Subjects:
Adsorption
Analytical biochemistry: general aspects, technics, instrumentation
Analytical, structural and metabolic biochemistry
Bacterial adhesion
Bacterial Adhesion - physiology
Biological and medical sciences
Caseins - pharmacokinetics
Evanescent wave
Force measurement
Fundamental and applied biological sciences. Psychology
Glass
Lasers
Optical trap
Staphylococcus aureus - physiology
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Summary:A technique for precisely measuring the equilibrium and viscous interaction forces between a single bacterium and a flat surface as functions of separation distance is described. A single-beam gradient optical trap was used to micromanipulate the bacterium against a flat surface while evanescent wave light scattering was used to measure separation distances. Calibrating the optical trap far from the surface allowed the trapped bacterium to be used as a force probe. Equilibrium force–distance profiles were determined by measuring the deflection of the cell from the center of the optical trap at various trap positions. Simultaneously, viscous forces were determined by measuring the relaxation time for the fluctuating bacterium. Absolute distances were determined using a best-fit approximation to the theoretical prediction for the hindered mobility of a diffusing sphere near a wall. Using this approach, forces in the range from 0.01 to 4 pN were measured at near-nanometer resolution between Staphylococcus aureus and glass that was bare or coated with adsorbed protein.
ISSN:0021-9797
1095-7103
DOI:10.1016/S0021-9797(03)00095-X