Cornell's quantum dot technology proven biologically safe

Feb. 23, 2009
NEW YORK, NY, USA--Researchers at Memorial Sloan-Kettering Cancer Center (MSKCC) report that "Cornell dots" are biologically safe, and are stable and small enough to be easily transported across the body's structures and efficiently passed through the kidneys. The MSKCC researchers also note that the Cornell University-developed quantum dots can reveal a cancer tumor's blood vessels, cell death, treatment response, and invasive or metastatic spread to lymph nodes and distant organs.

NEW YORK, NY, USA--Researchers at Memorial Sloan-Kettering Cancer Center (MSKCC, New York, NY) report that Cornell dots ("C dots") are biologically safe, and are stable and small enough to be easily transported across the body's structures and efficiently passed from the body through the kidneys. The MSKCC researchers also note that the Cornell University-developed 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. Their refinements to the quantum dots' original design, as well as and experiments in mice at MSKCC, are reported in Nano Letters by Wiesner, Dr. Michelle Bradbury, a physician-scientist specializing in molecular imaging and neuroradiology at MSKCC, and colleagues.

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.

"Highly sensitive and specific probes and molecular imaging strategies are critical to ensure the earliest possible detection of a tumor and timely response to treatment," said Bradbury. "Our findings may now be translated to the investigation of tumor targeting and treatment in the clinic, with the goal of ultimately helping physicians to better tailor treatment to a patient's individual tumor."

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

The latest research was supported by the Clinical and Translation Science Center at Weill Cornell Medical College and the Cornell Nanobiotechnology Center. The original research was funded by the National Science Foundation, New York state and Phillip Morris USA.

More information:
See the paper, Fluorescent Silica Nanoparticles with Efficient Urinary Excretion for Nanomedicine, in Nano Letters.

Posted by Barbara G. Goode, [email protected], for BioOptics World.

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