Cancer treatments could benefit from being more like a sniper and less like a shotgun blast. A new technique from Washington State University (WSU) is taking that approach, allowing doctors to attach gold nanoparticles to white blood cells and sneak them past the tumor's defenses for a targeted attack that doesn't affect healthy tissue.

The WSU researchers tested their technique in mice, with promising results. First, a tumor was implanted into the animal's side, before the area was exposed to near-infrared light. That induces inflammation, which attracts white blood cells called neutrophils to the site. Then, the researchers injected the mouse with gold nanoparticles treated with antibodies so they attach themselves to the neutrophils.

Normally, the researchers say, tumors surround themselves with a barrier of blood vessels, which makes it hard to get drugs inside, but the white blood cells can enter just fine, carrying the hitchhiking nanoparticles with them. Once inside enemy territory, the researchers then concentrate another pulse of near-infrared light to the area, which heats up the gold and kills the cancer cells from within.

This isn't the first time tiny specks of gold have helped scientists kill cancer. Gold nanobubbles, nanotubes and nanostars have been sent to infiltrate tumors in the past, but they're usually directed to the target by an attraction to certain proteins. The WSU study is the first time they've hitched a ride on white blood cells and, in future, the nanoparticles could be fitted with payloads of chemotherapy drugs.

"We have developed a new approach to deliver therapeutics into tumors using the white blood cells of our body," says Zhenjia Wang, lead researcher on the study. "This will be applied to deliver many anticancer drugs, such as doxorubicin, and we hope that it could increase the efficacy of cancer therapies compared to other delivery systems."

The research was published in the journal Advanced Materials.