title: Degradation of aqueous synthesized CdTe/ZnS quantum dots in mice: differential blood kinetics and biodistribution of cadmium and tellurium.
abstract: BACKGROUND
  Quantum dots (QDs) have been used as novel fluorescent nanoprobes for various bioapplications. The degradation of QDs, and consequent release of free cadmium ions, have been suggested to be the causes of their overall toxicity. However, in contrast to sufficient investigations regarding the biological fate of QDs, a paucity of studies have reported their chemical fate in vivo. Therefore, the overall aim of our study was to understand the chemical fate of QDs in vivo and explore analytical techniques or methods that could be used to define the chemical fate of QDs in vivo.
  
  
  METHODS
  Male ICR mice were administered a single intravenous dose (0.2 μmol/kg) of aqueous synthesized CdTe/ZnS aqQDs. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to simultaneously measure the concentrations of cadmium (Cd) and tellurium (Te) in the blood and tissues over the course of a 28 day period. We compared the blood kinetic parameters and biodistributions of Cd and Te, and used the molar ratio of Cd:Te as a marker for QDs degradation.
  
  
  RESULTS
  Cd and Te display different blood kinetics and biodistribution profiles. The Cd:Te ratio in the blood did not vary significantly within the first hour compared with intact CdTe/ZnS aqQDs. The Cd:Te ratio decreased gradually over time from the 6 h time point on. Cd accumulated in the liver, kidneys, and spleen. Te was distributed primarily to the kidneys. Sharp time-dependent increases in the Cd:Te ratio were found in liver tissues.
  
  
  CONCLUSIONS
  QDs can undergo degradation in vivo. In vitro, QDs are chemically stable and do not elicit the same biological responses or consequences as they do in vivo. Our methods might provide valuable information regarding the degradation of QDs in vivo and may enable the design and development of QDs for biological and biomedical applications.
authors.forename: Na
authors.initials: N
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Mu
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Hubo
authors.initials: H
authors.lastname: Sun
authors.forename: Sihai
authors.initials: S
authors.lastname: Han
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Li
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.forename: Peili
authors.initials: P
authors.lastname: Huang
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Sun
mesh_terms: D000818:Animals; D019187:Cadmium Compounds / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics*; D007275:Injections, Intravenous; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D008813:Mice, Inbred ICR; D045663:Quantum Dots; D013154:Spleen / Q000378:metabolism; D013440:Sulfides / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics*; D013691:Tellurium / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D017967:Zinc Compounds / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics*
chemical_list: D019187:Cadmium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C031238:zinc sulfide; D013691:Tellurium; C028337:cadmium telluride
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