Safer Nanoparticles Spotlight Tumors and Deliver Drugs

Last semester we spent a lab day discussing quantum dots, their promise for the future as well as the negative aspects currently associated with them such as leaving potentially harmful heavy metals in the body. Recently a research team led by Dr. Michael Sailor at the University of California, San Diego has developed miniscule flakes of silicon that glow brightly, last long enough to slowly release cancer drugs, then break down into harmless by-products. Like the quantum dots these silicon flakes can illuminate tiny tumors or precisely delivering drugs, but are unique in the fact that they are the first luminescent nanoparticles purposely designed to minimize toxic side effects, meeting the growing need for non-toxic alternatives that have a chance to make it into clinical treatment for human patients.
Like the quantum dots that we studied, the newly designed, safer luminescent particles can reveal tumors too tiny to detect by other means or allow a surgeon to be sure all of a cancerous growth has been removed. These nanoparticles could also help deliver drugs safely, by delivering the drug directly to the tumor, and releasing them into the tumor rather than other parts of the body. Targeted delivery would also allow doctors to use smaller doses of the drug, thus minimizing toxicity effects.
The ability for these safer nanoparticles to glow is a very useful property, but is also most commonly achieved by including toxic organic chemicals or quantum dots. When the researchers tested their safer nanoparticles in mice, (the first study to image tumors and organs using biodegradable silicon nanoparticles in live animals!) they saw tumors glow for several hours, then dim as the particles broke down. The levels dropped noticeably in a week and were undetectable after four weeks.This article was published in Feb 2009 on the Biomedical Engineering website EurekAlert, and can be found at http://www.eurekalert.org/pub_releases/2009-02/uoc--sns021809.php