Cutting laser microscope for nanosurgery

Fig. 1: Cutting of a single fiber within a living bovine endothelial cell. The pretensioned fiber snapps back and gives thus conclusions about the mechanic stability within the cell. The diameter of the fiber is < 1 µm.

In order to decipher and to utilize the vast number of information stored within a cell, the complexity of correlations and cell functions must be understood first. For this purpose, novel tools for both the analysis of and influence on the processes within living cells are required. A laser-assisted microscope setup developed at the LZH now enables not only to 3-dimensionally monitor cellular processes but also to influence the internal processes within a living cell.

For this purpose, a femtosecond laser with infrared laser pulses of only 100 fs (10-15s) is used. Due to the very high intensities at the focus of a microscope lense, a micro plasma is induced that causes a cutting effect. This has practically no effect on the environment and the procedure is minimal invasive and can thus also be used for influencing the low lying tissue.

One of the first fields of application came along in biomechanics. Cells consist of a filament-like inner network, the so-called cyto skeleton, that is particularly important for the tissue development and wound healing of an organism. Individual strings of the cyto skeleton were separated using the laser and the effect on the cell was analyzed. The so-called nanosurgery enables the selective manipulation of structures within a living cell to better understand the internal cellular processes. For example mitochondria, the “power stations” of a cell, can be selectively destroyed to gain new insights for cancer therapy. The author developed the laser microscope during a DFG-sponsored research employment in the group lead by Eric Mazur at Harvard University. In May, this development was awarded the Kaiser-Friedrich Research Award 2005.

Furthermore, in co-operation with Rowiak GmbH a “cutting microscope” should be developed that can easily be handled by cell biologists, medical doctors and pharmacists. This R&D project is carried out in co-operation with the University of Hannover and is sponsored by the Ministry of Economy of Lower Saxony within the scope of the biophotonics funding initiative.

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The Laser Zentrum Hannover e.V. (LZH) carries out research and development in the field of laser technology and is supported by the Ministry of Economic Affairs, Labour and Transport of the State of Lower Saxony (Niedersächsisches Ministerium für Wirtschaft, Arbeit und Verkehr).