Magazine article Science News

Laser Beam Can Pop out Single Cells

Magazine article Science News

Laser Beam Can Pop out Single Cells

Article excerpt

A laser that cuts out a cell and flips it into a waiting test tube offers researchers a way to remove single cells from a tissue sample in less than 30 seconds.

The technique offers a quick means to choose cells for DNA screening tests while minimizing contamination. This is especially important when applying the polymerase chain reaction, or PCR, a widely used method for making many copies of DNA or RNA (SN: 10/23/93, p. 262). Karin Schutze and Georgia Lahr of the Academic Hospital in Munich describe their new technique in the August Nature Biotechnology.

First, the researchers affix a slice of tissue to a thin plastic sheet and mount it on a glass slide above a highly focused ultraviolet laser. Looking through a microscope, they identify a particular cell, then burn around its edges with the laser, cutting out the cell like a cookie from a sheet of dough.

Then, by doubling the power of the laser but adjusting it to focus below the target cell, they launch the individual cell vertically off the glass slide and catch it with the cap of a test tube. The cell rides the stream of photons from the laser "like a surfer on top of a wave," says Lahr. The cell "can be beamed several millimeters away, even against gravity," she reports.

To demonstrate the selectivity of their technique, called laser pressure catapulting, Schtitze and Lahr collected individual colon cancer cells in test tubes. An analysis of the DNA of a single cell revealed the presence of a mutation that has been linked to colon cancer. …

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