|
We have developed a technique to disrupt submicrometer-sized organelles within living cells or tissue without affecting the surrounding material or compromising viability of the cell or organism. When a femtosecond laser pulse is tightly focused into a nearly-transparent biological material, energy is deposited by nonlinear absorption only in the focus where laser intensity is high, resulting in disruption of the structure in the focal volume. Because the absorption is confined to the small focal volume, the surrounding material is unaffected, allowing micrometer precision in the disruption of biological tissue. We have used this technique for disrupting single neural axons in living organisms and manipulating sub-cellular structures in live cells.
 |
 |
Laser cuts through actin fibers at different laser energies (1-4 nJ) in fixed BCE-cells. |
Stained BCE cell showing the actin network. |
In collaboration with the Ingber group at the Harvard Medical School we are studying the mechanical properties of the cell cytoskeleton. Current models of cellular structure describe the cell cytoskeleton as being composed of an interconnected network of microfilaments, microtubules, and intermediate filaments. These fibers link the nucleus and various organelles together with the cell membrane. This internal framework provides the cell with its shape and spatial stability, gives it motility and participates in apoptosis. Application of mechanical stress-induced alterations to the cell shape and structure have critical effects on many cellular functions, including growth, motility, contraction, and mechanotransduction. Our femtosecond laser system will be a tool for direct probing the cytoskeleton network and relate its function to cellular processes.
|
| Plainly speaking | To unveil information about cell mechanisms, cell-biologists rely on chemical or biological inhibition of functions, lacking spatially discrimination.
With the use of a laser focused by a microscope objective, one can achieve spatial resolutions in the µm-range. Near infrared femtosecond lasers are especially well suited for this kind of micromanipulation, as the energy deposited into the cell is very low and, thus, side effects, as high pressures or thermal damage, are minimized.
|
Cytoskeleton network in a fixed BCE-cell.
|
We are investigating the mechanical integrity and force distribution in the cytoskeletal fibers in collaboration with the Ingber-group at Harvard Medical School. Therefore, we are using the high spatial selectivity of the ultrashort laser to disrupt single microtubuli (30 nm in diameter) inside living cells.
|
|
Related publications