|The findings from this study indicate that following intravenous injection in mice, quantum dots may localize in important organs such as the kidney or liver, and they have a very long biological half-life. Such observations are important, given the potential for the use of quantum dots for biological imaging purposes in humans.|
Reviewed by Annette Santamaria, Ph.D., DABT, ENVIRON International Corporation.
- Yang R.S.H., Chang, L.W., Wu J., Tsai, M., Wang, H., Kuo, Y., Yeh, T., Yang, C.S., and Lin, P. (2007). “Persistent Tissue Kinetics and Redistribution of Nanoparticles, Quantum Dot 705, in Mice: ICP-MS Quantitative Assessment” Environmental Health Perspectives 115: 1339-1343.
Researchers are developing the use of autofluorescent quantum dot nanoparticles for biomedical imaging purposes, and it is likely that these nanoparticles will be used for these purposes in the future. However, there is concern over the lack of knowledge associated with exactly how quantum dots may localize within tissues and how they may be eliminated from the body once they are no longer needed for imaging. More research is required to evaluate tissue localization and kinetics of quantum dots in mice to understand how they may behave in humans.
To obtain information about the biopersistence of quantum dots in humans for use in biological imaging and other medical applications by (1) evaluating how quantum dots (QD705) localize in mice tissue and (2) assessing their toxicokinetic properties.
QD705 nanoparticles were injected intravenously into mice tail veins to mimic potential human medical imaging applications. Following a single injection, the quantitative blood and tissue kinetics of QD705 were evaluated in the mice for up to 28 days. In addition, two mass balance studies were conducted at 1 and 28 days after a single intravenous dose to determine if the administered dose could be recovered and to evaluate the distribution of QD705. The localization of QD705 in major target organs was also evaluated using fluorescence microscopy.
There are concerns about the potential for nanomaterials to localize in organs and tissues if they are systemically available. In addition, it is not known what the consequences of such tissue localization may be and it is not clear how biopersistent some nanomaterials may be, because little is known about they behave in the body (e.g., toxicokinetics). A few studies have reported that there is potential for quantum dots to accumulate in organs such as the kidney, which could lead to renal, and possibly, liver toxicity.
Tissue localizations of QD705 were observed in the kidneys (mainly at tissue lining parts of the liver and vessels and veins in the kidney). Initial findings revealed the persistent nature of QD705 (with regard to tissue kinetics) and predict a very long biological half-life, possibly in weeks or months, of QD705 nanoparticles in humans. The authors concluded that such long-term accumulation in organs such as the kidneys or liver could have adverse health consequences and that more thorough kinetic studies should be done on quantum dots or other nanoproducts that may be used for medical applications.