Are biosynthesized nanomaterials toxic for the environment? Effects of perlite and CuO/perlite nanoparticles on...

The properties of nanomaterials such as perlite nanoparticles and their increased application have raised concerns about their probable toxic impacts on the aquatic ecosystems and algae. Here, a novel biochemical synthesis and immobilization of CuO is reported on perlite nanoparticles (CuO/Per-NPs) and its toxic effect on alga has been compared with nanoperlites. This biosynthesis of CuO/Per-NPs performed using phytochemicals of Haematococcus pluvialis, Sargassum angustifolium, and walnut leaves in the aqueous extract. The structural, morphological, and colloidal properties of the as-synthesized nanoparticles have been confirmed by various methods. According to the obtained results, the morphology of the synthesized CuO/Per-NPs was spherical with sizes ranging from about 13 to 24 nm. Besides, the effects of Per-NPs and CuO/Per-NPs on unicellular algae H. pluvialis were studied. The changes in the amount of chlorophyll a, chlorophyll b, and Carotenoids in the presence of different concentrations of Per-NPs (25, 50, 100 mg/L) were more than CuO/Per-NPs. Also, decreased growth rate and efficiency of photosystem II confirmed the toxic effects of Per-NPs. However, the toxicity of CuO/Per-NPs appears to be lower than that of Per-NPs, which can be due to the changes in the surface and cationic charge of modified nanoperlit. These changes lead to a decrease in the interaction of nanoparticles with H. pluvilalis and a reduction in ROS production. Finally, the results of GC-MS used to evaluate volatile compounds, indicated an increase in the number of phenolic compounds in comparison to the control samples in 25, 50, and 100 mg/L treatments of nano-perlite.