Persistent tissue kinetics and redistribution of nanoparticles, quantum dot 705, in mice: ICP-MS quantitative assessment.
BACKGROUND
Quantum dots (QDs) are autofluorescent semiconductor nanocrystals that can be used for in vivo biomedical imaging. However, we know little about their in vivo disposition and health consequences.


OBJECTIVE
We assessed the tissue disposition and pharmacokinetics of QD705 in mice.


METHODS
We determined quantitatively the blood and tissue kinetics of QD705 in mice after single intravenous (iv) injection at the dose of 40 pmol for up to 28 days. Inductively coupled plasma-mass spectrometry (ICP-MS) measurement of cadmium was the primary method of quantification of QD705. Fluorescence light microscopy revealed the localization of QD705 in tissues.


RESULTS
Plasma half-life of QD705 in mice was short (18.5 hr), but ICP-MS analyses revealed QD705 persisted and even continued to increase in the spleen, liver, and kidney 28 days after an iv dose. Considerable time-dependent redistribution from body mass to liver and kidney was apparent between 1 and 28 days postdosing. The recoveries at both time points were near 100%; all QD705s reside in the body. Neither fecal nor urinary excretion of QD705 was detected appreciably in 28 days postdosing. Fluorescence microscopy demonstrated deposition of QD705 in the liver, spleen, and kidneys.


CONCLUSIONS
Judging from the continued increase in the liver (29-42% of the administered dose), kidney (1.5-9.2%), and spleen (4.8-5.2%) between 1 and 28 days without any appreciable excretion, QD705 has a very long half-life, potentially weeks or even months, in the body and its health consequences deserve serious consideration.
Yang
Raymond S H
RS
Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan, Taiwan.
Chang
Louis W
LW
Wu
Jui-Pin
JP
Tsai
Ming-Hsien
MH
Wang
Hsiu-Jen
HJ
Kuo
Yu-Chun
YC
Yeh
Teng-Kuang
TK
Yang
Chung Shi
CS
Lin
Pinpin
P
D000818:Animals; D007700:Kinetics; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D045663:Quantum Dots; D014018:Tissue Distribution