As published recently in Cancer Research and in Advanced Materials, Sangeeta Bhatia, professor of Health Sciences and Technology and Professor of Electrical Engineering and Computer Science, member of the David H. Koch Institute for Integrative Cancer Research at MIT and a Howard Hughes Medical Institute investigator, and HST graduate student Geoffrey von Maltzahn have developed a new method to both target and treat tumor cells using gold nanorods. Bhatia and von Maltzahn have discovered that these tiny particles are just the right substance and size to absorb energy from near-infrared light--emitting it as heat and destroying the tumor with minimal side effects. The nanorods will also be effective in diagnosing the particular tumor cells in question.
As cited May 4, 2009 by the MIT News Office article "Targeting tumors using tiny gold particles, Gold nanorods could detect, treat cancer," cancer now affects about seven million people worldwide and that number is projected to grow to 15 million by 2020. Because chemotherapy and/or radiation, the most common approaches to treat cancerous tumor cells can cause debilitating side effects and specifically in chemotherapy only one percent of drugs administered typically reach the tumor, the gold nanorods provide the most promising alternative method to date for accurately targeting the tumors and destroying the cancerous cells.
The gold nanorods, able to absorb different frequencies of light depending on their shape, can absorb light at near infrared frequency when shaped as rods. Once injected, the nanorods have been shown to disperse uniformly throughout the bloodstream, where they are ideally suited and sized (with a protective polymer coating) to enter the tumor cells through tiny pores in the localized blood vessels surrounding the tumors. Those nanorods that don't reach the tumor have been shown in laboratory tests to be discarded by the liver and spleen within three days.
Once the nanorods are absorbed by the tumor cells, a single exposure to a near-infrared laser will heat the nanorods (and not the surrounding tissues) up to 70 degrees Celsius--killing the tumor cells. At lower temperatures the rods have been shown to aid in the work of chemotherapy -- as a kind of follow up treatment -- and in cases where surgery might have left undetected cancer cells behind.
Through surface-enhanced Raman scattering--a process which takes advantage of rods treated with light absorbing molecules of differing properties--information on multiple issues concerning the tumor can be obtained.
Ultimately Bhatia and von Maltzahn hope to commercialize this technology - though clinical trials followed by FDA approval will take a number of years. Von Maltzahn won the Lemelson-MIT Student Prize in March, in part for his work with the nanorods.
The multi-phased work on developing the gold nanorods for cancer treatment has involved a larger team from MIT and elsewhere, including: Amit Agrawal, former postdoctoral associate in HST; Nanda Kishor Bandaru and Sarit Das of the Indian Institute of Technology, Madras; Andrea Centrone, postdoctoral associate in chemical engineering; Renuka Ramanathan, undergraduate in biological engineering; Alan Hatton, the Ralph Landau professor of Chemical Engineering; and Michael Sailor and Ji-Ho Park of the University of California at San Diego.
The research was funded by the National Institutes of Health, the Whitaker Foundation and the National Science Foundation. Nanopartz Inc. supplied gold nanoparticles, gold nanowires and the precursor gold nanorods used in this work.
- "Computationally Guided Photothermal Tumor Therapy Using Long-Circulating Gold Nanorod Antennas" Cancer Res. 2009 69: 3892-3900. Abstract
- "SERS-Coded Gold Nanorods as a Multifunctional Platform for Densely Multiplexed Near-Infrared Imaging and Photothermal Heating" Abstract, Advanced Materials, Digital Object Identifier (DOI)10.1002/adma.200803464, Geoffrey von Maltzahn 1, Andrea Centrone 3, Ji-Ho Park 4, Renuka Ramanathan 1, Michael J. Sailor 4 5, T. Alan Hatton 3, Sangeeta N. Bhatia 1 2 *
- "Gold star--Geoffrey von Maltzahn awarded $30,000 Lemelson-MIT Student Prize for innovations in fight against cancer," March 3, 2009, MIT News Office article.