Researchers at the Center for Nanoscale BioPhotonics (CNBP) have developed a new targeted treatment for cancer. Chemotherapy drugs are wrapped in "nano-bubbles" called liposomes, which are then injected into the desired part of the body and made to release their payload on demand, by applying X-ray radiation.

Liposomes are regularly used to protect drugs and carry them to where in the body they're needed. Over the years, we've seen them used to protect insulin doses from the harsh environment of the gut long enough for it to enter the bloodstream, disarm bacteria without using antibiotics, and escort cancer-killers to tumors.

"Liposomes are already well established as an extremely effective drug-delivery system," says Wei Deng, lead author of the study. "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. The issue however, is in controlling the timely release of the drug from the liposome."

In order to tackle that, the CNBP researchers designed their liposomes to collapse on demand, releasing the payload of drugs. Gold nanoparticles and molecules called verteporfin were embedded into the walls of the bubbles. When an X-ray pulse is applied, the verteporfin reacts with it to give off singlet oxygen, which bursts the bubble. The gold is there to help focus the energy and increase the reaction.

"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," says Ewa Goldys, senior researcher on the project. "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."

Bursting bubbles on demand to unleash drug payloads has been done before, but the trigger is usually ultrasound pulses.

The CNBP study was performed in mice, and the researchers say they plan to continue developing the liposomes to get the treatment ready for human clinical trials.

The research was published in the journal Nature Communications.

Source: CNBP