Effects of Cu x TiO y nanometer particles on biological toxicity during zebrafish embryogenesis

Abstract

This study investigated the toxicity of Cu (1, 10, 15, and 25 mol%) loaded TiO 2 and pure TiO 2 nanometersized photocatalysts during the development of zebrafish embryogenesis. The hatch rate decreased in the Cu x TiO y nanoparticles exposed groups (10, 20 ppt) compared to pure TiO 2 nano-particles (10, 20 ppt) exposed or control groups. These Cu x TiO y and TiO 2 nanoparticles led to developing mutated embryos with abnormal notochord formation, no tail, damaged eyes and abnormal heart development. Exposure to Cu x TiO y and pure TiO 2 nanoparticles led to glutathione increase, catalase activity increase, GST increase and GSR increase than control. Penetration of the Cu x TiO y and pure TiO 2 nanoparticles to the embryo was also tested. It was observed that Cu x TiO y and pure TiO 2 nanoparticles penetrated into cells. Moreover Cu x TiO y penetrated into the skin, nerve and yolk sac epithelium cells on the zebrafish larvae as aggregated particles, which may induce the direct interaction between nanoparticles and cell to cause adverse biological responses. As a result, the Cu-loaded TiO 2 nanoparticles had the toxicity of zebrafish embryo and larvae in the water environment.

Embryonic Toxicity of Nanoparticles

“…The exposure of zebrafish embryos to Culoaded TiO 2 NP revealed abnormal embryonic morphology, including edema and absence of tail and head ( table 1 ) [Yeo and Kang, 2009]. It was proposed that Cu x TiO y could enter into cells and affect their ion regulation, causing lethal injury to embryos.…”

“…Moreover, their penetration into mitochondria, activation of the immune response and changes in receptor or ion channel functions after NP incorporation must be considered. Also, interactions of NP with enzymes, potential apoptotic or necrotic factors and also induction of inflammatory processes must be taken into account [Kohen and Nyska, 2002;Yeo and Kang, 2009;Park et al, 2011Park et al, , 2013Zhao et al, 2013]. Furthermore, NP show virus-like properties, which can cause DNA damage and delays in cell proliferation [Asharani et al, 2008a].…”

The effect of nano-scale Zn-doped TiO2 and pure TiO2 particles on Hydra magnipapillata

“…The particles size of TiO 2 and Zn-doped TiO 2 was approximately 7-8 nm, smallest-size nano-scale particle to which aquatic living organisms were exposed in our previous investigation [12][13][14][15] . However, there were no critically toxic effects in the cnidarian Hydra magnipapillata, casting doubt on the hypothesis that, because small nanoparticles penetrate cells, the size of the nano-scale material is the reason for its toxicity [12][13][14][15]23 .…”

“…This finding is not in agreement with previous reports 15,23 , which showed that gene expression was altered in the nano-scale silver particle-treated zebrafish embryos, leading to phenotypic changes in the hatched larvae and reflecting increased apoptosis and incomplete formation of an axis 15 . Moreover, the major phenotypic alteration, suggesting injury from nanoparticle exposure, was inflammation, which caused apoptosis in genetically-damaged cells exposed to nano-silver or Cu-doped TiO 2 nanoparticles [12][13][14][15]23 .…”

“…Although nano-scale TiO 2 and ZnO do not penetrate human skin [9][10][11] , both enter the aquatic environment via wastewater effluent (Wiench et al, 2009). In previous reports, we investigated the toxic impacts of nano-scale particles on aquatic ecosystems using nano-silver or Cu-doped TiO 2 nanoparticles [12][13][14][15] . We found that rat and human alveolar macrophages had impaired function due to aggregation of ultrafine carbon particles, which may be linked to an increased risk of infection and inflammation of lung cells 16,17 . However, the relationship between the size effects of nano-scale materials and the biological toxicity is an inadequate explanation for the observed toxicity.…”