Micromanipulation of biological particles with optical tweezers

Bayoudh, Sonia (1999). Micromanipulation of biological particles with optical tweezers Master's Thesis, School of Physical Sciences, The University of Queensland.

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Author Bayoudh, Sonia
Thesis Title Micromanipulation of biological particles with optical tweezers
School, Centre or Institute School of Physical Sciences
Institution The University of Queensland
Publication date 1999-01-01
Thesis type Master's Thesis
Supervisor Halina Rubinzstein-Dunlop
Norman R. Heckenberg
Total pages 125
Language eng
Subjects 240402 Quantum Optics and Lasers
Formatted abstract

Following the first demonstration in 1987 by Arthur Ashkin of trapping of biological objects with infrared laser light, optical tweezers have become increasingly useful and versatile tool in a variety of non-contact micromanipulation experiments in biological applications. In this thesis we demonstrated various applications of optical tweezers in botanical sciences, chemical engineering and anatomical sciences. The investigation of the three-dimensional shape of spinach chloroplasts has been accomplished. This was done using a steerable and a stationary trap system. A trapped rotating calcite crystal positioned close to a chloroplast provided means for inducing the rotation and orientation of chloroplast. The utility of rotating birefringent particles is demonstrated for the first time in biological applications. The stirrer method is a versatile method in orienting any biological object to study its shape and/or structure. Also, we demonstrated the ability of optical tweezers to fix and displace chloroplasts inside a living spinach plant cell.


In the second part of the work described in this thesis, the steerable trap was used to study the viscoelastic properties of a polymeric filament that connects a single bacterium to an activated sludge floc. Also we estimated the minimum bonding force that can cause a weak interaction between the bacterium surface and the filament using optical tweezers as a transducer. This force was estimated to be at least 10 pN. These measurements are of value in improving activated sludge flocculation and ultimately the wastewater treatment process. In addition, the steerable trap was used to move small organelles inside large bacteria cells. The repositioning of organelles resulted in creating new internal cell structure.


In the final part of the thesis, experiments are described where the laser tweezers system was combined with a cw argon-ion laser microbeam to investigate the fusion of smooth muscle cells and macrophages. In order to minimize the optical damage to the cells, a special arrangement was established to create short pulses for cutting the contact of the cell membrane of the two-fusion cell partners. The effectiveness of the cutting function of the pulsed system when used at 488 nm wavelength varied from cell to cell. The laser parameters such as laser power, pulse duration and repetition rate were varied in order to obtain the best working function of the setup. But overall the results indicate that the relatively long (µs) pulses possible may not be well suited to such applications.

Keyword Particles -- Optical properties
Laser beams
steerable traps
optical tweezers
biological micromanipulation
Additional Notes The full thesis is held in the Australian Digital Theses Program site and is available from there - http://adt.library.uq.edu.au/public/adt-QU2000.0027/index.html

Document type: Thesis
Collection: UQ Theses (non-RHD) - UQ staff and students only
Citation counts: Google Scholar Search Google Scholar
Created: Tue, 30 Mar 2004, 10:00:00 EST