Femtosecond Lasers for Nanosurgery

Roland Piquepaille writes "In "Lasers operate inside single cells," Nature writes that nanosurgery can be achieved by vaporizing some components of living cells without killing the cells themselves. "With pulses of intense laser light a millionth of a billionth of a second long, US researchers are vaporizing tiny structures inside living cells without killing them. The technique could help probe how cells work, and perform super-precise surgery." This was developed by Eric Mazur of Harvard University and his colleagues. This summary contains more details and references about the process and these microexplosions. Please note that it's a very different technique from the one described six months ago in a previous Slashdot reference, Surgery with Femtosecond Lasers."

Comments

Re:Evolution

[azzy]

I suggest you read The Blind Watchmaker, that goes into such things.

Re:Couldn't this be used for hi-res printing?

[hankwang]

>same technology be used to alter ink colors for super high-resolution laser printing?

The whole point of the article is that the laser beam can modify something embedded inside a cell without affecting the surface of the cell. This is not an issue with laser printing. What you are describing is actually built into any CD/DVD burner. One bit on a CD is about 1500 nm in size, or on a DVD 500 nm. 500 nm per pixel corresponds to 50 kDPI.

Of course, the mechanics that control the position of the laser need to be redesigned, but for what purpose other than data storage would you want a 10 kDPI image? Note that the resolution is insufficient for "writing" holograms.

Re:Units of Length

[rco3]

Of course, this is wrong. Stupid me; multiplied where I should have divided.

The correct answer is 2.7432x10^-9 football fields, or two and three-quarters nanofootballfields.

Assuming, of course, that you meant American football.

Femtosecond Lasers and Eye Surgery

[narakas]

I used to work on a biomedical project at the Univ. of Michigan involving high-speed lasers (usually femtosecond duration) as a tool to replace the larger ablative lasers used in standard refractive surgery (LASIK). The femtosecond lasers could be focused intrastromally, such that the material ablated was directly inside the cornea. Due to the relaxation of some stromal pressure, the cornea itself would reshape to a softer lens, without the huge amount of ablation required by current lasers. http://www.intralase.com/home.html

Re:genetics

[Mercaptan]

It's a nice thought, but even these lasers aren't precise enough to alter genes on living chromosomes.

Mitochondria are about 5 micrometers across and your various cytoskeletal filaments and tubules range between 3 - 25 nanometers in diameter.

Human chromosomes, on the other hand, are essentially 2 meters of DNA packed into a 5 micrometer-wide nucleus. Now that's 6 billion base pairs (A/T's and G/C's), which are wrapped up pretty tight.

If you stretched out the DNA to full length, that's 3.4 x 10e-10 meters per base pair. Taking a randomish gene that's 10,000 base pairs long, that would work out to 3.4 micrometers of DNA, which this laser could work on. But if you think refolding maps is hard, imagine trying to repack 2 meters of DNA back into a 5 micrometer nucleus.

During metaphase, when the cell has all its chromosomes lined up and ready for splitting, the average size of a chromosome is 2 micrometers from end to end. Basically, your 10k base pair gene is now just 1.7 nanometers long. All of this winding and compacting means that it's blessedly hard to hit a single gene and only that gene within the DNA contained in a living cell with a tool this blunt.