Korean scientists have used table salt to help them move closer to creating a porous silicon nanobomb that will literally blow up cancerous cells.

Thermotherapy - that uses near infra-red (NIR) light to destroy cells - stopped being used in the 1990s, but thanks to new research is making a comeback as a possible alternative to currently available therapies for removing cancerous cells. Recently agents such as carbon nanotubes - that emit heat after irradiation with NIR - have been tried in combination with thermotherapy to kill cancer cells selectively. 

Last year Chongmu Lee and co-workers at Inha University, Incheon, found that porous silicon offered a non-toxic and biodegradable alternative to carbon nanotubes for killing breast cancer cells. Now in vitro tests have shown that a suspension of porous silicon in sodium chloride solution offers better results still, say the researchers.

The researchers avoid killing healthy cells by taking advantage of the folic acid- and antibody-receptors that are over abundant in most cancer cells. They pre-treat the porous silicon in sodium chloride solution with folic acid or antibodies, so that the agent binds selectively to the cancer cells before irradiation.

'Porous silicon can substantially lower the illumination intensities of NIR necessary to obtain heating effect sufficient to destroy cancer cells down to a level which can be actually used in the clinic,' says Lee.

Lisa DeLouise, an expert in porous silicon at the University of Rochester Medical Centre in the US, says 'nanoparticle thermotherapy is an emerging field with great potential for biomedical research'. 

Lee is continuing his research with in vivo tests, before moving on to clinical trials. He will go on to use the explosive properties of porous silicon to form a nanobomb for cancer treatment by finding a biocompatible oxidant to trigger heating. He is also working on a similar titanium dioxide system.

Sylvia Pegg