Abstract
The 96 h acute toxic effects of nano-CuO (N-CuO), micro-CuO (M-CuO) and 2+ on Chlorella sp. were investigated in this paper. The results showed that toxicities decreased in an order of Cu2+＞N-CuO＞M-CuO. The 96 h EC50 of Cu2+ on Chlorella sp. was 1.06 mg /L, and of N-CuO it was 74.61 mg /L, while no pronounced toxicity was observed when the concentration of M-CuO was lower than 160 mg/L. Further experiments were carried out in order to study the toxicity mechanism of nano-CuO on Chlorella sp.. The results of Cu2+ release from N-CuO showed less than 0.2 mg/L Cu2+ were released, so the release of Cu2+ was not responsible for the toxicity. Further experiments showed N-CuO inhibited formation of Chlorophyll A. Content of Chlorophyll A in the control group was 4.75 mg/108 cells, while it declined to 2.89 mg/108 cells for 160 mg/L N-CuO after 96 h, which indicated that N-CuO could inhibit photosynthesis of Chlorella sp.. Moreover, N-CuO condensed with algal cells. It affected the activity of SOD and POD, indicating that N-CuO could cause oxidant stress to Chlorella sp.. These may be the toxicity mechanism.
Highlights
As a frontier technology, nano-science, as well as information science and life science, are the top three pillar sciences in contemporary society
Content of Chlorophyll A in the control group was 4.75 mg/108 cells, while it declined to 2.89 mg/108 cells for 160 mg/L N-CuO after 96 h, which indicated that N-CuO could inhibit photosynthesis of Chlorella sp
The TEM analysis is shown in Figure 1; M-CuO, analytical reagent,was bought from Sinopharm Chemical Reagent CO., Ltd, with average particular size of 30 μm measured via Laser Particle Size Analyzers in Figure 2; CuCl2H2O, analytical reagent, was bought from Tianjin Guangcheng Chemical Reagent CO., Ltd; Other reagents were all analytical; Chlorella sp. was obtained from the Fisheries College of Ocean University of China
Summary
Nano-science, as well as information science and life science, are the top three pillar sciences in contemporary society. Nano-CuO (N-CuO) has been applied to catalysts, superconductors, thermoelectric materials, sensor materials, glass, ceramics and other areas. It can be used as burning rate catalyzers. In a word, it is a kind of widely applied nano-material. Sensitive, having short growth cycle, easy to be cultivated separately and owning observable toxic effects directly from a cellular level, algae are often used for risk assessment as the sensitive factors to environmental toxic substances. The toxic studies on N-CuO are still limited, so we carry on this study to investigate the toxic effects of N-CuO on Chlorella sp., aiming to assess the safety of nano-material, and provide evidence for standard use of nano-material
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