X-ray triggered nano-bubbles can target cancer

Scientists have developed drug filled nano-bubbles that can be triggered in the body by standard X-rays and may pave the way for a new range of cancer treatments.

The tiny bubbles, known as liposomes, are commonly used in pharmacology to encapsulate drugs, making them more effective in the treatment of disease.

Researchers have now been able to engineer these liposomes to discharge their drug cargo on-demand, once activated by standard X-rays. Initial testing has shown this technique to be highly efficient in killing bowel cancer cells.

"The development and application of various nanomaterial designs for drug delivery is currently a key focus area in nanomedicine," said Wei Deng, who was a scientist at Macquarie University in Australia.

"Liposomes are already well established as an extremely effective drug-delivery system," said Deng.

"Made out of similar material as cell membranes, these 'bubbles' are relatively simple to prepare, can be filled with appropriate medications and then injected into specific parts of the body," she said.

The issue however, is in controlling the timely release of the drug from the liposome," she added.

"We have ensured that the liposomes release their drug pay-load at exactly the right time and in exactly the right place to ensure the most effective treatment," said Deng.

"One way of doing this is to trigger the collapse of the liposome when and where it is needed. Our X-ray triggerable liposomes allow this on-demand drug-release to occur," she said.

"The approach we took was to embed gold nanoparticles and the photo-sensitive molecule verteporfin into the wall of the liposome," she added.

The radiation from the X-ray causes the verteporfin to react and to produce highly reactive singlet oxygen which then destabilises the liposomal membrane, causing the release of the drug, researchers said.

The gold nanoparticles are added into the mix as they focus the X-ray energy. This enhances the singlet oxygen generation and hence improves the speed of the membrane breakup, they added.

"Our X-ray triggered liposomes were loaded with the chemotherapy drug, doxorubicin, which killed the cancer cells far more effectively than without X-ray triggering," said Ewa Goldys, a professor at Macquarie University.

"We then tested our liposomes to determine effectiveness against bowel tumours. Tumours treated with our liposomes gradually shrunk over the two week test period which is an extremely encouraging result," Goldys said.