Gold nanorods 'punch holes in cancer cell membranes'

In collaboration with the Press Association

Scientists have found that they can blast holes in the membranes of tumour cells by applying a laser beam to tiny gold 'nanorods'.

Researchers at Purdue University exploited the fact that many tumour cells need folate, a form of vitamin C, by attaching folate to the gold nanorods, each of which measures just 15 x 50 nanometres (one nanometre is one millionth of a millimetre).

The nanorods target receptor sites in the tumour cell membranes that are specifically designed to capture molecules of folate, meaning that the nanorods can be heated up using a laser beam and cause damage to the cell membrane.

Ji-Xin Cheng, assistant professor at Purdue's Weldon School of Biomedical Engineering, explained that the near-infrared light from the laser beam "can easily pass through tissue, but is absorbed by the nanorods and converted rapidly into heat, leading to miniature explosions on the cell surface".

Alexander Wei, associate professor of chemistry at Purdue, said that when a nanorod becomes hot, it produces an event "like a tiny bomb".

"Then suddenly you have a gaping hole where the nanorod was."

The researchers also found that tumour cell death is chemically-induced. The nanorods cause blistering, or 'blebbing', of the tumour cell membrane, although not as a direct result of the heat.

Professor Cheng explained: "The blebbing is triggered by the nanorods, but it's really caused through a complex biochemical pathway - a chemically induced process.

"Extra calcium gets into the cell and triggers enzyme activity, which causes the infrastructure inside the cell to become loose, and that gives rise to the membrane blebs."

Professor Cheng added: "We like to believe this opens the possibility of using nanorods for biomedical imaging as well as for therapeutic purposes."

The research will be published in Advanced Materials this week.