Gold nanoparticles have been investigated in a number of cell lines and organisms in terms of their absorption and toxicity. These studies show that gold particles are taken up into cells and organisms, but are not or only slightly toxic.

 

Water fleas take up their food by filtering water. If the water contains gold nanoparticles, they are detected within a short time in the intestines of animals. However, they are not absorbed from the intestine into the surrounding tissue. If the fleas are then kept in particle-free water, the particles are transported through the intestine and excreted [1]. Only very high concentrations caused a mortality in water fleas, reproduction and embryo development was not affected by nanoscale gold [2]. However, particles were observed to adhere to the carapaceof the animals, affecting both the swimming behavior and the molting rate.

 

Gold nanoparticles (3, 10, 50 and 100 nm) were demonstrated to be incorporated into zebrafish embryos, but did not lead to malformations or to increased mortality [3]. Gold nanoparticles with a size of 12 nm can pass through the pores which are also used for the transport of other substances into the zebrafish embryo [4]. The particle transport is carried out passively and concentration-dependent, i.e. the more particles are present in the vicinity of the embryo, the higher is the concentration in the embryo. The uptake of particles is accompanied by a small increase in mortality compared to control, and a likewise small increase in the number of malformations of the developing fish.

In gold-nanoparticle-exposed liver cells of rainbow trout, the formation of reactive oxygen species was observed. However, these had no effects on the viability of the cells. Gold nanoparticles and gold ions in the same concentrations had similar effects on the cells. This shows that probably not the nanoparticulate form, but the element gold causes the observed effects. A simultaneous exposure to dissolved organic materials, as those found in normal surface water, does not change the effect of the nanoparticles [5].

 

Blue mussels accumulated gold nanoparticles almost exclusively in their digestive glands. In addition, the particles triggered oxidative stress in the glands, but not in the gill and mantle tissue [6]. These results were confirmed for two different particle sizes (~5 and ~13 nm) [7]. For another shell species, the basket shell, similar findings have been described [8].

 

In a study of bacteria, cucumber and lettuce plants 10 nm gold nanoparticles exerted no toxic effects [9]. For the solvent used much stronger effects were observed than for the nanoparticles alone. Gold nanoparticles had a positive influence on the growth of lettuce plants, as an increase in shoot growth was observed after 15 days of exposure [10]. Amine-coated gold nanoparticles adhered to the surface of algal cells, as a consequence a concentration-dependent growth reduction of 20-50 % was observed. However, no particles were incorporated into the algal cells [8].

 

Luminescent bacteria treated with nanoscale gold took up the particles and showed a decrease in their luminosity [11]. The change of this parameter was caused by a slowdown of cell metabolism, but not with increased mortality. No influence on bacterial growth behavior was observed for gold nanoparticles coated with polyethylene glycol (PEG) (30 nm) [12]. The number of microorganisms in the soil was reduced by gold nanoparticles, but only a very small extent [10].

 

In summary, despite an uptake of nanoscale gold in the cells or the intestines of many organisms, little toxic effects were observed. Comparing the organisms studied, algae reacted the most sensitive to exposure to gold nanoparticles.

 

Literatur arrow down

  1. Lovern, SB et al. (2008), Nanotoxicology, 2(1): 43-48.
  2. Li, T et al. (2010), Anal Bioanal Chem, 398(2): 689-700.
  3. Bar-Ilan, O et al. (2009), Small, 5(16): 1897-1910.
  4. Browning, LM et al. (2009), Nanoscale, 1(1): 138-152.
  5. Farkas, J et al. (2010), Aquat Toxicol, 96(1): 44-52.
  6. Tedesco, S et al. (2010), Aquat Toxicol, 100(2): 178-186.
  7. Tedesco, S et al. (2010), Comp Biochem Physiol C Toxicol Pharmacol, 151(2): 167-174.
  8. Renault, S et al. (2008), Gold Bulletin, 41(2): 116-126.
  9. Barrena, R et al. (2009), Chemosphere, 75(7): 850-857.
  10. Shah, V et al. (2008), Water, Air, and Soil Pollution, 197(1-4): 143-148.
  11. Zheng, HZ et al. (2010), Anal Sci, 26(1): 125-128.
  12. Williams, DN et al. (2006), J Nanobiotechnology, 4 3.

 

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