Lasers operate inside single cells
Nanosurgery vaporizes cellular components leaving rest intact.
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.
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. The energy is about equal to the impact of a flying gnat, says Mazur: "A cell can easily take that."
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.
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.