Researchers at Memorial Sloan-Kettering Cancer Center report that Cornell dots ("C dots") are biologically safe; they are stable inside the body and are easily excreted by the kidney.The MSKCC researchers also note the quantum dots can reveal the extent of a cancer tumor's blood vessels, cell death, treatment response, and invasive or metastatic spread to lymph nodes and distant organs.

C dots were developed in 2005 at Cornell University by Hooisweng Ow, then a graduate student working with Ulrich Wiesner, associate professor of materials science and engineering.

A single dot consists of several dye molecules encased in a silica shell that can be as small as 5 nanometers in diameter. The silica shell, essentially glass, is chemically inert. Coating the dots with polyethylene glycol, a process called PEGylation, further protects them from being recognized by the body as foreign substances, giving them more time to find targeted tumors.

The outside of the shell can be coated with organic molecules that will attach to such desired targets as tumor surfaces or even locations within tumors. The cluster of dye molecules in a single dot fluoresces under near-infrared light much more brightly than single dye molecules, and the fluorescence will identify malignant cells, showing a surgeon exactly what needs to be cut out and helping ensure that all malignant cells are found.

Since creating the Cornell dots, Wiesner, Ow and Kenneth Wang '77 co-founded the company Hybrid Silica Technologies to commercialize the invention. The dots also have possible applications in microarrays such as DNA chips, in addition to non-biomedical realms.

Source: BioOptics world.

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