Lasers Will Soon Zap Vaccines Directly Into Cells

July 29, 2010— -- Drugs and vaccines could one day make their way into your body at the speed of light. Scientists from Georgia Tech can now blast a hole in a cell, place a molecule inside and seal it back up a split second later using a laser pulse.

The new technique could deliver drugs, vaccines and other molecules that otherwise wouldn't be able to get past a cell's defenses.

"Cells are surrounded by membranes, which keep what's inside, inside, and what's outside, outside," said Mark Prausnitz, a scientist at Georgia Tech and co-author of the new Nature Nanotechnology paper. "There is very little that can pass through the membrane, but our goal is to put molecules into cells that have a hard time getting (there)."

Laser beams are only the latest way to deliver an outlying molecule inside a cell.

Specialized channels embedded in the cell membrane actively pump some molecules into and out of the cell. If a molecule looks the part, it can slip past the cell membrane. Viruses use a special needle-like appendage to inject their genetic material into a cell. Certain chemicals and electrical charges can also temporarily puncture cell membranes.

Each technique has its advantages, such as ease or specificity, and its disadvantages, such as unwanted genetic code in the case of viruses. The Georgia Tech team wanted to create a new method that maximized the advantages while minimizing the disadvantages.

The researchers used a laser beam pumping pulses of infrared light and blackened nanoparticles of carbon -- "otherwise called soot," said Prausnitz -- which are placed next to the cells.

The laser pulse heats the soot particle, creating a tiny bubble around it. When the pulse ends, the bubble violently collapses, creating a shockwave that blows a hole in the cell membrane. The effect is similar to the ultrasonic waves used to clean jewelry, said Prausnitz.

A fraction of a second later, the cell membrane heals itself -- or at least that's the case with most cells. Ten percent of the cells used in the experiment died because the shockwave was too powerful.

"It's a tightrope we have to walk," said Prausnitz. "We have to make a hole that is big enough for molecules to go in, but not big enough that the cell is damaged and dies."

The hole is only open for a split second. In that time, however, molecules that otherwise couldn't enter the cell can now have an opportunity.

That short window of time could be exploited by drugs for chemotherapy, DNA for a vaccine or genetic engineering, and more, said Prausnitz.

"This is a very unique combination of a nanomaterial and laser to accomplish an important task," Samir Mitragotri, a scientist at the University of California at Santa Barbara, who described the research as quote "remarkable" and "very innovative."

Lasers won't be vaccinating anyone anytime soon, however. The research was done in the lab, and it will take years before the technique is approved for use in humans.