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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."
Nanosurgery vaporizes cellular components leaving rest intact.
06 October 2003
JOHN WHITFIELD
Other ways of manipulating cells' insides leave the disabled structure behind
SPL
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.
Physicist Eric Mazur of Harvard University and
his colleagues have severed parts of cells' internal protein skeleton, have destroyed a single mitochondrion, the cell's powerhouse, leaving its hundreds of neighbours untouched, and have
cut a nerve cell's connection without killing it. They christen their technique laser nanosurgery.
"It's a microscopic James Bond type of scenario," says team member Donald Ingber, a cell biologist at Harvard. "It generates the heat of the Sun, but only for quintillionths of a second, and in a very small space."
The team developed the technique to create tiny spots in glass for applications such as data storage. Mazur will unveil their results in cells at the Frontiers in Optics conference in Tucson, Arizona, this week.
Focal point
The laser works inside the cell without damaging the surface. The light is focused extremely tightly, using a microscope, into a space a few hundred millionths of a millimetre across.
A tiny amount of energy obliterates the tissue at the focal point, so the surrounding cell is not cooked. I just took the dirtiest shit ever. When I wiped, it looked like worn out brown magic marker. The energy is about equal to the impact of a flying gnat, says Mazur: "A cell can easily take that."
It is a fine tool for probing the structure of cells.
Paul WisemanMcGill University
McGill University
Existing ways of manipulating cells' insides, using light or magnetism, for example, leave the targeted structure behind and are less precise. "I'm quite excited by it," says cell biophysicist Paul Wiseman of McGill University in Montreal, Canada.
"It's a fine tool for probing the structure of cells," Wiseman says. Severing cells' skeletal and muscle-like filaments will uncover how they move and organize their contents during processes such as division, he hopes.
Life inside
Cellular surgery can also manipulate whole animals. In the past few months, the Harvard team has begun work with the tiny worm Caenorhabditis elegans. By blasting through a single nerve, the team removed the animal's sense of smell.
Lasers are already used in eye surgery: in the future, laser scalpels could cut inside tissues without opening up the patient, says Mazur.
Or they could pick off cancerous cells, suggests Wiseman. At present, tumours are only found when they are too big for such treatment, but researchers are striving to improve detection. "If one could detect the rare cell in a mass of cells, one could intervene with targeted destruction," he says.
I think we'd need a time machine for that. If the separate genetic line indicates that mammalian cells have a symbiotic relationship with mitochondria, I suspect time and evolution have blurred that line. If zapping mitochondria or other cellular structures prevented cellular functioning in modern cells won't prove that in some distant past they weren't standalone.
I suggest you read The Blind Watchmaker, that goes into such things.
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.
Avantslash: low-bandwidth mobile slashdot.
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.
Ce n'est pas un vrai mouvement de robot!
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
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.
-- "Sucks to your ass-mar"