Biological Effects Of Artificial Nanomaterials On Alga

In recent years, with the mass production and widespread use of nanomaterials, its biological safety aroused great concern from people. How to effective and accurate assess the toxic effects of nanomaterials which have become a spotlight. Alga took on an important role in water environment as that of the primary producer, and it used to select as model organism in toxicological study. Therefore, it was essential that the toxic effects of nanomatericals on alga were investigated. This paper focused on the toxic effects of nanomaterials on the growth of alga cells, the content of chlorophyll a and soluble protein in Chlorella vulgaris, Scenedesmus obliquus and Scenedesmus quadricanda. The sensitivity of algas to nanomaterials was also studied. The acute toxicity test of alga for detecting the toxic of nanomaterials has been established. This paper aimed to address the assessment method and provid the supporting data for the safety of nanomaterials.This paper obtained the following results:(1) Based on acute toxicity tests, the growth effects of nine nanooxides and two nanosilver on Chlorella vulgaris, Scenedesmus obliquus and Scenedesmus quadricanda were investigated. The results showed that different nanomaterials on the growth of alga were distinct. The nanomaterials accelerated (or less inhibited) the growth of alga at a lower concentration, the growth of alga was inhibited with the increasing concentration of nanomaterials. The toxicity of nZnO on three algas was higher. By contrast, nNiO,nTiO2 (rutile and anatase) and nFe3O4 indicated the lower toxicity than nZnO. And the toxicity of nSiO2,nFe2O3(γandα) and nAl2O3 was the lowest. The toxicity of nAg on three algas was the highest. And the toxicity of nAg(colorless) was much lower than that of nAg(brown). Furthermore, the toxicity of anatase was much higher than that of rutile, and the toxicity of nFe2O3(γ) was much lower than that of nFe2O3(α). In the three algas, the sensitivity of Chlorella vulgaris to nanomaterials was the highest, and that of Scenedesmus quadricanda to nanomaterials was the lowest.(2) The effects of nanomaterials on the content of chlorophyll a of different alga were studied and the toxic mechanism of nanomaterials was discussed. The results showed that the nanomaterials could promote the content of chlorophyll a at a lower concentration, which was consistent with the results of the growth inhibition test. With the increasing concentration of nanomaterials, nanomaterials exhibited toxic effects. The chloroplasts were destroyed and physiological function declined.(3) The effects of nanomaterials on content of protein on alga were detected. It turned out that nanomaterials at lower concentration could improve the content of protein in alga cells. And it could hinder the biosynthesis of protein at higher concentration.(4) The sensitive Chlorella vulgaris was select as the tested organism, the toxic effects of different nanomaterials was investigated. The toxic effects of nano zinc oxide which were the same type but different sizes and nano titanium dioxide, silver-loaded nanomaterials which were the same size but different types were also studied. It aimed to confirm the method which the acute toxicity tests of alga for detecting the toxic of nanomaterials could work well. The results indicated that the method could distinguish the toxic effects of different nanomaterials including different scale and crystal of nanomaterials.In sum, the toxic of nanomaterials impacted on the growth of alga cells, chlorophyll and protein of alga.The toxicity of nanomaterials was related to partical size, crystal form, and so on. It was feasible that the acute toxicity tests of alga could distinguish the toxicity of nanomaterials.