In recent years, lasers for optical trapping and micromanipulation of microscopic particles or cells and sub cellular structures, both in vivo and in vitro, have gained remarkable interest in biomedical research and applications. Although the principles and the mechanisms of pulsed laser ablation have been well described for macroscopic interventions, the microbeam operation under microscopic guidance necessitates further investigation. In this work, we present the research and development efforts towards a pulsed ultraviolet microbeam laser system, the design and realization efforts towards a near infrared laser trapping device and the results obtained on yeast cells and algae by the combined system. We investigated the optical dissection of the cells versus the presence of optical trapping forces and the presence of rhodamine dye. We characterized the optical ablation of the cell walls and resulting cavitation as plasma formation effects which create shock waves due to their occurrence only in nanosecond pulse irradiation mode. We estimated the minimum energy of the microbeam for optical dissection of yeast cell, under the influence of optical trapping forces, as lower as 3 μJ, while in the presence of rhodamine as lower as 2 μJ. Lastly, using the techniques of optical microsurgery we demonstrated the minimum energy value for sub cellular dissection on an algae cell equal to 27 μJ.

Date Published: 15 March 2013
PDF: 8 pages
Proc. SPIE 8770, 17th International School on Quantum Electronics: Laser Physics and Applications, 877019 (15 March 2013); doi: 10.1117/12.2013660

Published in SPIE Proceedings Vol. 8770:
17th International School on Quantum Electronics: Laser Physics and Applications
Tanja N. Dreischuh; Albena T. Daskalova, Editor(s)