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Degradation of aqueous synthesized CdTe/ZnS quantum dots in mice: differential blood kinetics and biodistribution of cadmium and tellurium.

Liu N, Mu Y, Chen Y, Sun H, Han S, Wang M, Wang H, Li Y, Xu Q, Huang P, Sun Z - Part Fibre Toxicol (2013)

Bottom Line: The Cd:Te ratio in the blood did not vary significantly within the first hour compared with intact CdTe/ZnS aqQDs.Sharp time-dependent increases in the Cd:Te ratio were found in liver tissues.In vitro, QDs are chemically stable and do not elicit the same biological responses or consequences as they do in vivo.

View Article: PubMed Central - HTML - PubMed

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.

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Characteristics of CdTe/ZnS aqQDs: (A) AFM image, (B) absorption and emission spectra. The average size was 19.3 ± 2.2 nm in diameter. The maximal emission was observed at approximately 652 nm following excitation at 350 nm.
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Figure 1: Characteristics of CdTe/ZnS aqQDs: (A) AFM image, (B) absorption and emission spectra. The average size was 19.3 ± 2.2 nm in diameter. The maximal emission was observed at approximately 652 nm following excitation at 350 nm.

Mentions: For atomic force microscopy (AFM) measurements, only the Z-dimension was used to determine the size in order to avoid probe-related artifacts. These measurements yielded a mean size of 19.3 ± 2.2 nm. The shape of the CdTe/ZnS aqQDs was approximately spherical (Figure 1A). The emission spectra of the aqQDs are presented in Figure 1B. The maximal emission was 652 nm (at λex = 350 nm). The concentration of the CdTe/ZnS aqQDs stock solution was 2.5 μmol/ml (calculated based on the molar mass of Cd). The Cd:Te ratio was 3:1, and the molar ratio of zinc (Zn) to Cd (Zn:Cd) was 1:1.


Degradation of aqueous synthesized CdTe/ZnS quantum dots in mice: differential blood kinetics and biodistribution of cadmium and tellurium.

Liu N, Mu Y, Chen Y, Sun H, Han S, Wang M, Wang H, Li Y, Xu Q, Huang P, Sun Z - Part Fibre Toxicol (2013)

Characteristics of CdTe/ZnS aqQDs: (A) AFM image, (B) absorption and emission spectra. The average size was 19.3 ± 2.2 nm in diameter. The maximal emission was observed at approximately 652 nm following excitation at 350 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750282&req=5

Figure 1: Characteristics of CdTe/ZnS aqQDs: (A) AFM image, (B) absorption and emission spectra. The average size was 19.3 ± 2.2 nm in diameter. The maximal emission was observed at approximately 652 nm following excitation at 350 nm.
Mentions: For atomic force microscopy (AFM) measurements, only the Z-dimension was used to determine the size in order to avoid probe-related artifacts. These measurements yielded a mean size of 19.3 ± 2.2 nm. The shape of the CdTe/ZnS aqQDs was approximately spherical (Figure 1A). The emission spectra of the aqQDs are presented in Figure 1B. The maximal emission was 652 nm (at λex = 350 nm). The concentration of the CdTe/ZnS aqQDs stock solution was 2.5 μmol/ml (calculated based on the molar mass of Cd). The Cd:Te ratio was 3:1, and the molar ratio of zinc (Zn) to Cd (Zn:Cd) was 1:1.

Bottom Line: The Cd:Te ratio in the blood did not vary significantly within the first hour compared with intact CdTe/ZnS aqQDs.Sharp time-dependent increases in the Cd:Te ratio were found in liver tissues.In vitro, QDs are chemically stable and do not elicit the same biological responses or consequences as they do in vivo.

View Article: PubMed Central - HTML - PubMed

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.

Show MeSH
Related in: MedlinePlus