NIR Quantum Dots Studied for Cancer Treatment

HAYWARD, Calif., Jan. 5 -- Researchers have developed an improved method for performing sentinel lymph node biopsy, a crucial first step in determining whether a cancer has spread to other parts of the body. The new method depends on quantum dots, nanometer-sized crystals that emit near-infrared (NIR) light, to illuminate lymph nodes during cancer surgery. The research, resulting from collaboration between researchers at MIT, Beth Israel Deaconess Medical Center and Brigham and Women's Hospital, will be published in the January issue of Nature Biotechnology.

The new NIR quantum dots were developed and synthesized at the MIT department of chemistry in the laboratory of Professor Moungi Bawendi, a scientific co-founder and advisory board member of Quantum Dot Corp. (QDC). The novel, intraoperative NIR fluorescence imaging system was developed in the laboratory of John Frangioni, assistant professor of medicine and radiology at Harvard Medical School and an attending physician at Beth Israel Deaconess Medical Center.

The study, entitled "Near-Infrared Fluorescent Type-II Quantum Dots for Sentinel Lymph Node Mapping," by Sungjee Kim and colleagues, describes how the quantum dots were injected into live pigs and followed visually to the lymph system just beneath the skin of the animals. The new imaging technique allowed the surgeons to clearly see the target lymph nodes without cutting the animals' skin.

Sentinel lymph node (SLN) mapping, the surgical technique employed in the study, is a common procedure used to identify the presence of cancer in a single "sentinel" lymph node, thus avoiding the removal of a patient's entire lymph system. SLN mapping relies on a combination of radioactivity and organic dyes but the technique is inexact during surgery, often leading to removal of much more of the lymph system than necessary. The study reported that the new imaging system with NIR quantum dots was a significant improvement over the dye/radioactivity method currently used.

"SLN mapping has already revolutionized cancer surgery," Frangioni said. "Near-infrared quantum dots have the potential to improve this important technique even further."

Carol Lou, president of QDC, said although the technique is several years away from being a reality for patients, "this is a wonderful demonstration of the potential of quantum dot nanotechnology to significantly enhance medical care."

For more information, visit: www.qdots.com