[Hplusroadmap] Femtosecond laser scalpel for single-cell surgery

[Bryan Bishop]

http://www.utexas.edu/news/2008/06/23/laser_surgery/

Laser Surgery Probe Targets Individual Cancer Cells

June 23, 2008

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AUSTIN, Texas — Mechanical engineering Assistant Professor Adela 
Ben-Yakar at The University of Texas at Austin has developed a 
laser "microscalpel" that destroys a single cell while leaving nearby 
cells intact, which could improve the precision of surgeries for 
cancer, epilepsy and other diseases.

"You can remove a cell with high precision in 3-D without damaging the 
cells above and below it," Ben-Yakar says. "And you can see, with the 
same precision, what you are doing to guide your microsurgery."

Femtosecond lasers produce extremely brief, high-energy light pulses 
that sear a targeted cell so quickly and accurately the lasers' heat 
has no time to escape and damage nearby healthy cells. As a result, the 
medical community envisions the lasers' use for more accurate 
destruction of many types of unhealthy material. These include small 
tumors of the vocal cords, cancer cells left behind after the removal 
of solid tumors, individual cancer cells scattered throughout brain or 
other tissue and plaque in arteries.

A commercially available femtosecond laser system and microscope was 
developed recently for LASIK and other eye surgeries, but the system's 
bulk limits its usefulness. Ben-Yakar's laboratory has overcome 
technological challenges to create a microscope system that can deliver 
femtosecond laser pulses up to 250 microns deep inside tissue. The 
system includes a tiny, flexible probe that focuses light pulses to a 
spot size smaller than human cells.

Ben-Yakar's experimental system and its use to destroy a single cell 
within layers of breast cancer cells grown in the laboratory is 
described in the June 23 issue of Optics Express.

Within a few years, Ben-Yakar expects to shrink the probe's 
15-millimeter diameter three-fold, so it would match endoscopes used 
today for laparoscopic surgery. The probe tip she has developed also 
could be made disposable—for use operating on people who have 
infectious diseases or destroying deadly viruses and other 
biomaterials.

To develop the miniature laser-surgery system, Ben-Yakar worked with 
co-author Olav Solgaard at Stanford University's Electrical Engineering 
Department to incorporate a miniaturized scanning mirror. Ben-Yakar and 
her graduate student Chris Hoy, another co-author, also used a novel 
fiber optic cable that can withstand intense light pulses traveling 
from an infrared, femtosecond laser. To make the intensity more 
manageable, they stretched the light pulses into longer, weaker pulses 
for traveling through the fiber. Then they used the fiber's unique 
properties to reconstruct the light into more intense, short light 
pulses before entering the tissue.

For the study, Ben-Yakar directed laser light at breast cancer cells in 
three-dimensional biostructures that mimic the optical properties of 
breast tissue. She has since studied laboratory-grown, layered cell 
structures that mimic skin tissue and other tissues.

Ben-Yakar is also investigating the use of nanoparticles to focus the 
light energy on targeted cells. In research published last year, she 
demonstrated that gold nanoparticles can function as nano-scale 
magnifying lenses, increasing the laser light reaching cells by at 
least an order of magnitude, or 10-fold.

"If we can consistently deliver nanoparticles to cancer cells or other 
tissue that we want to target, we would be able to remove hundreds of 
unwanted cells at once using a single femtosecond laser pulse," 
Ben-Yakar says. "But we would still be keeping the healthy cells alive 
while photo-damaging just the cells we want, basically creating 
nanoscale holes in a tissue."

Grants from the National Science Foundation and the National Institute 
of Health funded the research.

Photos of Ben-Yakar are available online.

Learn about a larger-scale, higher precision femtosecond laser system 
that Ben-Yakar uses to study nerve regeneration.

For more information, contact: Daniel Vargas, Cockrell School of 
Engineering, 512-471-7541;  Adela Ben-Yakar, Department of Mechanical 
Engineering, Cockrell School of Engineering, 512-475-9280.

I think I passed her in the hall yesterday.

- Bryan
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http://heybryan.org/