Quantum Dots may consist of toxic metal compounds such as Cadmium-Telluride and Cadmium-Selenide. Toxic effects of Quantum Dots have been described due to the leaching of metal compounds. The coating of Quantum Dots also affects their toxicity. Numerous surface modifications were developed to prevent the leaching of toxic metals. Also the light quality and quantity play a role for the effect, UV-B irradiation toxifies the particles.

 

Water flea with ingested fluorescent quantum dots (pink colour). © Lewinski et al., 2010.Water flea with ingested fluorescent quantum dots (pink colour). © Lewinski et al., 2010.

Different amounts of Quantum Dots with different coatings are ingested by water fleas; accordingly the excretion differs depending on the type of coating [1]. The size was found to have no effect on the uptake [2]. For various bacteria and water fleas, certain groups of Quantum Dots are toxic, although here, too, the type of coating and UV-light has an influence on the strength of the effect [3,4,5,6]. The more heavy metals leach out, the greater the toxic effect [3,4,7]. In the presence of environmentally relevant compounds binding to heavy metals, the toxic effects are reduced [5,8]. Some Quantum Dots are able to slow down the microbial decomposition of dead organic materials in the environment [9], i.e. they inhibit the activity of the bacteria.

 

Certain groups of Quantum Dots suspended in aqueous solutions proved to be toxic to algae [10]. There was an inhibition of the photosynthetic performance of algae, i.e. the use of light for nutrition was limited [11]. An uptake of the particles into algal cells was not observed. Instead, the particles adhered to the algal cell wall. When Quantum Dot-exposed algae were fed to water fleas, the Quantum Dots could be detected in the fleas. Hence, a transfer of Quantum Dots through the food chain from lower to higher organisms takes place [12]. To diatoms, cadmium-containing quantum dots were cytotoxic depending on the release of the cadmium ions [13]. This toxicity can be reduced by a surface coating, which prevents the release of cadmium ions.

 

In rainbow trout, the exposure to certain groups pf Quantum Dots had a negative influence on the immune system [14]. Liver cells of rainbow trout were also damaged, depending on the release of cadmium [15]. In zebrafish embryos, negative effects were observed. These were due to the various metal components of the Quantum Dots, which dissolve in small amounts, but also partly to the type of surface coating [16].

 

In summary, intact Quantum Dots, in particular those that do not emit toxic metal ions, are considered to be of low toxicity. Generally, for assessment of the toxicity of Quantum Dots, the type of surface coating has to be considered. With an extended persistence in the environment, increased release of toxic metals  from heavy metal-containing quantum dots is associated, which have a toxic effect on organisms in the environment. However, a number of organic compounds in the environment, provided they are present, may bind the metal ions.

 

Literatur arrow down

  1. Lewinski, NA et al. (2010), Environ Sci Technol, 44(5): 1841-1846.
  2. Jackson, BP et al. (2009), Anal Bioanal Chem, 394(3): 911-917.
  3. Kim, J et al. (2010), Aquat Toxicol, 97(2): 116-124.
  4. Lee, J et al. (2010), Environ Toxicol, 25(6): 593-600.
  5. Mahendra, S et al. (2008), Environ Sci Technol, 42(24): 9424-9430.
  6. Pereira, R et al. (2011), J Hazard Mater, 194 345-354.
  7. Pace, HE et al. (2010), Environ Toxicol Chem, 29(6): 1338-1344.
  8. Lee, S et al. (2011), J Nanopart Res, 13(7): 3051-3061.
  9. Gao, J et al. (2011), J Hazard Mater, 186(1): 940-945.
  10. Wang, J et al. (2008), Chemosphere, 73(7): 1121-1128.
  11. Lin, SJ et al. (2009), J Phys Chem C, 113(25): 10962-10966.
  12. Bouldin, JL et al. (2008), Environ Toxicol Chem, 27(9): 1958-1963.
  13. Xu, M et al. (2010), Metallomics, 2(7): 469-473.
  14. Gagné, F et al. (2010), J Environ Monit, 12(8): 1556-1565.
  15. Gagné, F et al. (2008), Nanotoxicology, 2(3): 113-120.
  16. King-Heiden, TC et al. (2009), Environ Sci Technol, 43(5): 1605-1611.

 

 

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