A wide variety of experiments have shown that nanoscale quantum dots have the potential to detect early-stage cancer and even monitor the progress of anticancer therapies.
But a new study from a team of investigators at the Center for Cancer Nanotechnology Excellence Focused (CCNE) on Therapy Response suggests that quantum dots as they currently exist may not remain in the body long enough to prove useful in human clinical applications.
Sanjiv Gambhir, M.D., Ph.D., principal investigator of the Stanford University-based CCNE, along with fellow CCNE investigators Anna Wu, Ph.D., and Xiaoyuan Chen, Ph.D., used positron emission tomography (PET) to track the fate of radioactively labeled quantum dots labeled after injection into mice. After injection, PET imaging revealed that as much as a half of the quantum dots were removed from the blood stream by the liver and spleen and that the entire dose was removed from circulation within 10 minutes of injection. Quantum dots coated with poly(ethylene glycol) (PEG), a biocompatible polymer used to extend the circulating lifetime of many types of nanoparticles, fared little better. The size of the quantum dots also had little effect on blood clearance rates.