Scientists are increasingly turning to nanoparticles in search of new ways to treat cancer. Tiny nanorobots that wade through the bloodstream and microscopic particles that blow up diseased cells are a couple of menacing examples. But none sound quite so ominous as a new technique under development at North Carolina State University (NCSU). Its researchers have designed liquid metal particles they describe as "Nano-Terminators" that latch onto cancer cells to more effectively deliver drugs that kill them off.

The process begins with gallium indium alloy, a liquid metal that NCSU scientists seem to have some affinity for. Last year, they used it in the development of metals capable of changing surface tension and shape, in a promising step toward morphing electronics and perhaps even self-assembling terminator-style robots.

In using gallium indium alloy to take the fight to cancer, a team led by assistant professor in joint biomedical engineering Zhen Gu placed the liquid metal in a solution that contained two different types of molecules, known as polymeric ligands. Applying an ultrasound to the solution then caused the metal to bust apart into tiny droplets, each measuring around 100 nanometers in diameter.

As the droplets separate, both ligands bind to their surface where an oxidized skin also begins to form. These together avoid the droplets from fusing together into larger particles. A common chemotherapy drug doxorubicin is then mixed into the solution. One type of ligand sucks up the drug and holds it inside, while the other ligand serves the purpose of actively targeting cancer cells and binding with receptors on their surface.

In testing the particles on a mouse model, the team introduced the Nano-Terminators into the bloodstream. Here it found the cancer cells absorbed the nanodroplets, with the high level of acidity inside the cells breaking down the oxidized skin. This in turn released the ligands and the doxorubicin, attacking the cancer cells from the inside out. The team reports the technique to be "significantly more effective" at suppressing ovarian tumor growth than doxorubicin alone.

In addition, as the liquid metal dissolves it releases gallium ions which the researchers say further boosts the effectiveness of anticancer drugs. The team also claims that the material is biodegradable after tracking the mice for up to 90 days and finding no signs of resulting toxicity.

The research team now plans to conduct additional testing in a larger animal study, with a view to moving toward clinical trials.

The research is to be published today in the journal Nature Communications.

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