‘Spasers’ could destroy circulating tumor cells on command

In the original Star Wars film, a pre-Jedi Luke Skywalker practices his light sabre skills against a floating ball that zaps him from time to time with an annoyingly painful laser. Researchers in Georgia say something like that, but a billion times smaller, could be injected into the human bloodstream to target and destroy circulating tumor cells (or CTSs). (Update: An astute reader suggests a better Star Wars analogy would be so-called Buzz Droids, which attach themselves to the outside of ships and try to break the ship open mid-flight. Duly noted.)

A so-called spaser is a nanoparticle about 20 nanometers across with folic acid on its surface. Folate receptor is chemical overexpressed on the surface of most human cancer cells, meaning tumor cells will take up the spaser particles at a far higher rate than non-cancerous cells. By drinking a nanoparticle cocktail or through direct injection into the blood, doctors can target tumor cells, then shine a light that heats the spaser, causing a shock wave that breaks the cancer cells apart.

Incidentally, spaser stands for surface plasmon amplification by stimulated emission of radiation. In the Georgia study, researchers focused on a nanoparticle composed of a gold sphere with a silica shell covered in a uranine dye used for medical diagnostics. The scientists found the particles had a low toxicity and when irradiated, successfully killed the tumor cells while leaving healthy human cells unharmed. The researchers looked at human cells in vitro (in a dish), and mouse cells in vivo (in the body).

Said Mark Stockman, director of the Center for Nano-Optics and professor of physics at Georgia State: “There is no other method to reliably detect and destroy CTCs…. This is the first. This biocompatible spaser can go after these cells and destroy them without killing or damaging healthy cells. Any other chemistry would damage and likely kill healthy cells. Our findings could play a pivotal role in providing a better, life-saving treatment option for cancer patients.”

Metastatic cancer happens when the disease spreads from its site of orgin to other parts of the body like the liver, lungs and brain. At thst stage it’s often hard to treat and one of the most dangerous ways metastasizing occurs is through the CTCs. The Georgia spaser findings are published in the journal Nature Communications.

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