Glowing ‘C dots’ stick to cancer cells

When exposed to near-infrared light, the dots fluoresce much brighter than unencapsulated dye to serve as a beacon to identify the cancer cells. (Credit: Cornell)

Researchers are testing a new camera system that uses fluorescent nanoparticles called C dots to make cancer cells glow, giving surgeons a clear view of cancer in real time.

It’s called the Artemis Fluorescence Camera System and is being used in a clinical trial with melanoma patients who have lesions in the head and neck region, says Uli Wiesner, professor of materials science and engineering at Cornell University and inventor of the fluorescent “C dots” (Cornell dots)

During an earlier clinical trial, radiologists injected C dots into melanoma patients to see whether the dots are safe and where they would go. But now, for the first time, they will use the C dots in conjunction with the Artemis system to image nodal disease in melanoma patients.

“This is extremely exciting, because in general it is the first time an optical inorganic nanoparticle probe will be used in a surgery room in conjunction with an optical camera to help surgeons identify nodal disease during surgery,” Wiesner says. “This is what we have worked toward all these years, and it will finally happen.”

For the new trial, they will first inject the C dots around the primary lesion in the head and neck. Then, using the Artemis camera, they will observe how the C dots are taken up by the lymphatic system and end up in the lymph nodes adjacent to the tumor. If those nodes contain cancer cells, the C dots should stick to them and glow. If the nodes are cancer-free, the C dots will not stick, and the fluorescence will be transient.

The clinical trial is being conducted at Memorial Sloan Kettering Cancer Center.

What are C dots?

C dots are silica spheres less than 8 nanometers in diameter that enclose several dye molecules. (A nanometer is one-billionth of a meter, about the length of three atoms in a row.) The silica shell, essentially glass, is chemically inert and small enough to pass through the body and out in the urine. For clinical applications, the dots are coated with polyethylene glycol so the body will not recognize them as foreign substances.

To make the dots stick to tumor cells, organic molecules that bind to tumor surfaces or even specific locations within tumors can be attached to the shell. When exposed to near-infrared light, the dots fluoresce much brighter than unencapsulated dye to serve as a beacon to identify the target cells. The technology, the researchers say, can show the extent of a tumor’s blood vessels, cell death, treatment response, and invasive or metastatic spread to lymph nodes and distant organs.

Source: Cornell University