microPET-based biodistribution of quantum dots in living mice.
This study evaluates the quantitative biodistribution of commercially available CdSe quantum dots (QD) in mice.


METHODS
(64)Cu-Labeled 800- or 525-nm emission wavelength QD (21- or 12-nm diameter), with or without 2,000 MW (molecular weight) polyethylene glycol (PEG), were injected intravenously into mice (5.55 MBq/25 pmol QD) and studied using well counting or by serial microPET and region-of-interest analysis.


RESULTS
Both methods show rapid uptake by the liver (27.4-38.9 %ID/g) (%ID/g is percentage injected dose per gram tissue) and spleen (8.0-12.4 %ID/g). Size has no influence on biodistribution within the range tested here. Pegylated QD have slightly slower uptake into liver and spleen (6 vs. 2 min) and show additional low-level bone uptake (6.5-6.9 %ID/g). No evidence of clearance from these organs was observed.


CONCLUSIONS
Rapid reticuloendothelial system clearance of QD will require modification of QD for optimal utility in imaging living subjects. Formal quantitative biodistribution/imaging studies will be helpful in studying many types of nanoparticles, including quantum dots.
Schipper
Meike L
ML
Departments of Radiology and Bioengineering, Bio-X Program, Molecular Imaging Program at Stanford (MIPS), Stanford University, East 150 Clark Center, Palo Alto, CA 94305, USA.
Cheng
Zhen
Z
Lee
Sheen-Woo
SW
Bentolila
Laurent A
LA
Iyer
Gopal
G
Rao
Jianghong
J
Chen
Xiaoyuan
X
Wu
Anna M
AM
Weiss
Shimon
S
Gambhir
Sanjiv S
SS
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D019187:Cadmium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D003301:Copper Radioisotopes; D008099:Liver / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D011092:Polyethylene Glycols / Q000737:chemistry; D049268:Positron-Emission Tomography / Q000379:methods; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D013154:Spleen / Q000378:metabolism; D014018:Tissue Distribution; D017967:Zinc Compounds / Q000737:chemistry / Q000493:pharmacokinetics
D019187:Cadmium Compounds; D003301:Copper Radioisotopes; D018036:Selenium Compounds; D017967:Zinc Compounds; D011092:Polyethylene Glycols; C058667:cadmium selenide; C044696:zinc selenide
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