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Proceedings Paper

Optical tweezers for the measurement of binding forces: system description and application for the study of E. coli adhesion
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Paper Abstract

Optical tweezers together with a position sensitive detection system allows measurements of forces in the pN range between micro-sized biological objects. A prototype force measurement system has been constructed around in inverted microscope with an argon-ion pumped Ti:sapphire laser as light source for optical trapping. A trapped particle in the focus of the high numerical aperture microscope-objective behaves like an omni-directional mechanical spring if an external force displaces it. The displacement from the equilibrium position is a measure of the exerted force. For position detection of the trapped particle (polystyrene beads), a He-Ne laser beam is focused a small distance below the trapping focus. An image of the bead appears as a distinct spot in the far field, monitored by a photosensitive detector. The position data is converted to a force measurement by a calibration procedure. The system has been used for measuring the binding forces between E-coli bacterial adhesin and their receptor sugars.

Paper Details

Date Published: 19 June 2003
PDF: 10 pages
Proc. SPIE 4962, Manipulation and Analysis of Biomolecules, Cells, and Tissues, (19 June 2003); doi: 10.1117/12.504304
Show Author Affiliations
Erik G. Fallman, Umea Univ. (Sweden)
Staffan Schedin, Umea Univ. (Sweden)
Magnus J. Andersson, Umea Univ. (Sweden)
Jana Jass, Lawson Health Research Institute (Canada)
Ove Axner, Umea Univ. (Sweden)


Published in SPIE Proceedings Vol. 4962:
Manipulation and Analysis of Biomolecules, Cells, and Tissues
Dan V. Nicolau; Joerg Enderlein; Robert C. Leif; Daniel L. Farkas, Editor(s)

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