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nanotimes News in Brief Cancer Research //

Breast Cancer Cells Burned by Gold-filled Silicon Wafers © Based on Material by The Methodist Hospital Research Institute

12-01 :: January 2012

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cientists at The Methodist Hospital Research Institute (U.S.) have successfully targeted and burned breast cancer cells.

“Hollow gold nanoparticles can generate heat if they are hit with a near-infrared laser,” said Research Institute Assistant Member Haifa Shen, M.D., Ph.D., the report‘s lead author. ”Multiple investigators have tried to use gold nanoparticles for cancer treatment, but the efficiency has not been very good – they‘d need a lot of gold nanoparticles to treat a tumor.”

Instead, Shen and his colleagues turned to a tech- nology developed by the study‘s principal investiga- tor, Mauro Ferrari, Ph.D., The Methodist Hospital Research Institute (TMHRI) president and CEO, to amplify the gold particles‘ response to infrared light.

“We developed a system based on Dr. Ferrari‘s multi-stage vector technology platform to treat cancers with heat,” Shen said. “We found that heat generation was much more efficient when we loaded gold nanoparticles into porous silicon, the carrier of the multistage vectors.”

Shen and his team found that in the presence of 808nm light, the gold-filled silicon particles heated up a surrounding solution in some minutes. The tem-

perature rose from 25° C (absolute) to 45° C (absolu- te) in a few minutes (77° F to 113° F). Water particles immediately around the particles were presumed to have been hotter. And experiments showed that tu- mor cell growth was lowest in the presence of gold- loaded silicon nanoparticles in three types of breast cancer cells – MDA-MB-231 and SK-BR-3 (human), and 4T1 (mouse).

The silicon wafers the scientists are using are the result of painstaking work by Ferrari‘s group to de- sign nanoparticles that preferentially bind to breast cancer cells, rather than, say, healthy liver or im- mune system cells. The shape and size of the silicon particles, as well as their surface chemistry, are all crucial, Ferrari‘s group found. Too big or the wrong shape, and the silicon nanoparticles bind to multiple cell types – or none at all. Polyamine structures are attached to the wafers to improve their attraction to cancer cell surfaces and their solubility. The wafers are about one micrometer in diameter. By contrast, the typical breast cancer cell is about 10 to 12 times that size.

Shen says the gold particles, too, must be designed with a specific use in mind, albeit for indirect rea- sons.