Aqueous Hg(2+) associates with TiO2 nanoparticles according to particle size, changes particle agglomeration, and becomes less bioavailable to zebrafish

Aquat Toxicol. 2016 May;174:242-6. doi: 10.1016/j.aquatox.2016.02.017. Epub 2016 Feb 24.


Engineered nanoparticles (NPs) have unique physicochemistry and potential to interact with other substances in the aqueous phase. Here, gene [metallothionein 2 (mt2)] expression changes in larval zebrafish were used to evaluate the association between aqueous Hg(2+) and TiO2 (NPs and bulk particle size control) to investigate the relationship between changes in Hg(2+) behavior and TiO2 size. During 24h exposures, TiO2 agglomerates increased in size and in the presence of 25μg Hg(2+)/L, greater increases in size were observed. The concentration of Hg(2+) in suspension also decreased in the presence of TiO2-NPs. Mercury increased expression of mt2 in larval zebrafish, but this response was lessened when zebrafish were exposed to Hg(2+) in the presence of TiO2-NPs, and which suggests that TiO2-NPs alter the bioavailability of Hg(2+) to zebrafish larvae. This ameliorative effect of TiO2 was also likely due to surface binding of Hg(2+) because a greater decrease in mt2 expression was observed in the presence of 1mg/L TiO2-NPs than 1mg/L TiO2-bulk. In conclusion, the results show that Hg(2+) will associate with TiO2-NPs, TiO2-NPs that have associated Hg(2+) will settle out of the aqueous phase more rapidly, and agglomerates will deliver associated Hg(2+) to sediment surfaces.

Keywords: Mercury; Metallothionein; Sorption; Titanium dioxide nanoparticles; Zebrafish.

MeSH terms

  • Animals
  • Biological Availability
  • Gene Expression Regulation / drug effects*
  • Mercury / chemistry*
  • Mercury / toxicity
  • Metallothionein / genetics
  • Nanoparticles / chemistry*
  • Particle Size
  • Titanium / chemistry*
  • Water Pollutants, Chemical / toxicity
  • Zebrafish*


  • Water Pollutants, Chemical
  • titanium dioxide
  • Metallothionein
  • Titanium
  • Mercury