Transformation of CuO nanoparticles by ions in the solution and their effects on copper toxicity and bioaccumulation in zebrafish embryo

• Main Authors: Lam, Chi-Cuong, 林志强
• Other Authors: Huang, Chih-pin
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/3r6fp8

碩士 === 國立交通大學 === 環境工程系所 === 107 === With the rapid development of nanotechnology in the last few decades, there have been increasing concerns over the impact of nanoparticles (NPs) to human health, when they are released into aquatic environment, especially for copper oxide NPs (CuO NPs). CuO NPs is one of the common NPs, which is widely used in many industrial and agricultural applications. Once CuO NPs are released into the aquatic environment, the transformation of CuO NPs (i.e., hydrodynamic size and solubility) may occur, leading to change in their toxicity. Apart from the pH and natural organic matter (NOM), ion concentrations (i.e., ionic strength) is one of the typical parameters that directly affect the fate and transport of CuO NPs in aquatic environment. Therefore, this study investigated transformation of CuO nanoparticles by ions in the solution and their effects on copper toxicity and bioaccumulation by monitoring the responses and uptake behaviors of zebrafish embryo. In this study, two copper sources were used, including copper nanoparticles (copper oxide nanoparticle, CuO NPs) and Cu ions. Besides, the simulated waters were prepared according to the ionic strength (IS) of surface water (SW), groundwater (GW), and wastewater (WW), which was 1.5, 15 and 54 mM, respectively. Acute toxicity & teratogenicity and bioaccumulation of CuO NPs and Cu ion were investigated using zebrafish embryo. The results showed that SW caused the transformation of CuO NPs by reducing the hydrodynamic size and increasing the solubility, and led to the changes in toxic potential. The effect of CuO-NPs was mainly contributed to delay zebrafish hatching time and increase malformation instead of the mortality. In SW, for example, the mortality of zebrafish was 20% at the concentration of 10 mg CuO/L and only 18.7% of embryos had successful hatching. At the same concentration of CuO NPs, the rise of IS enhanced the hatched embryos (18.7%, 25.6% and 30.3% for SW, GW, and WW, respectively). Similarly, the total abnormal development of embryo was reduced by the increase of IS (48.6%, 34% and 27% for SW, GW, and WW, respectively). Furthermore, the heartbeat of larvae in SW was lowered than those obtained in GW and WW with the exposure 10 mg CuO/L (27.8 ± 2.9, 28 ± 3.4 and 28.9 ± 2.4 beats/10s). In SW, approximately 15% of larvae had the heartbeat below 25 beats/10s in the concentration of 10 mg CuO/L, while this value was only around 5% in WW. Moreover, in SW, 35% of uptake copper was found in inside zebrafish embryo. In contrast, there was only 15% in WW. Besides, the small diameter of CuO NPs in SW mainly accumulated in the heart of zebrafish larvae, whereas the big size of CuO NPs in GW and WW was found abundantly in body axis and tail. In summary, the low IS solution (e.g., SW) could drop the hydrodynamic size and raise the solubility of CuO NPs. Thereby, the toxic potential of CuO NPs was enhanced in the low IS solution. The SW not only induced the reduction of hatching rate and heartbeat but also resulted in the increase of mortality and malformation. Therefore, the release of CuO NPs into low IS solutions such as surface water or groundwater would raise many concerns about their toxicity and bioaccumulation.