The increased applications of nanomaterials in industry and biomedicine have resulted in a rising concern about their possible toxic impacts on living organisms. It has been claimed that the phytosynthesized nanomaterials have lower toxicity in comparison to their chemically synthesized counterparts. Therefore, it is important to evaluate their toxic effects on the environment. In the present study, we investigated the toxic effects of microwave-synthesized silver-reduced graphene oxide nanocomposites (MS-Ag-rGO) on Chlorella vulgaris. Algal cells were treated by 1, 2, 4 and 6 mg L-1 MS-Ag-rGO for 24 h. The obtained data with three replicates were examined using analysis of variance. Analysis of different growth parameters revealed that MS-Ag-rGO possessed significant dose-dependent toxic effect on C. vulgaris. Scanning electron microscope and fluorescence microscope images of the treated cells established morphological shrinkages and alteration in position of nucleoli. Moreover, reduction in the phenol and flavonoid contents, enhancement of H2O2 content, changes in the antioxidant enzymes activity and decreases in the growth parameters as well as photosynthetic pigments quantities confirmed the toxicity of MS-Ag-rGO to the C. vulgaris cells. Our findings revealed that MS-Ag-rGO possessed higher toxicity on C. vulgaris than Ag-rGO synthesized by hydrothermal technique.

中文翻译：

---

微波合成的银还原氧化石墨烯纳米复合材料对微藻小球藻的毒性：与水热法合成的同行比较。

纳米材料在工业和生物医学中的越来越多的应用已引起人们越来越关注它们对生物的可能的毒性影响。据称，与化学合成的对应材料相比，植物合成的纳米材料具有较低的毒性。因此，重要的是评估它们对环境的毒性作用。在本研究中，我们调查了微波合成的银还原氧化石墨烯纳米复合材料（MS-Ag-rGO）对小球藻的毒性作用。用1、2、4和6mg L-1 MS-Ag-rGO处理藻类细胞24小时。使用方差分析检查获得的具有三个重复的数据。对不同生长参数的分析表明，MS-Ag-rGO对寻常梭菌具有明显的剂量依赖性毒性作用。处理细胞的扫描电子显微镜和荧光显微镜图像确定了核仁位置的形态缩小和位置改变。此外，苯酚和类黄酮含量的减少，H2O2含量的增加，抗氧化酶活性的变化以及生长参数的降低以及光合色素的含量证实了MS-Ag-rGO对寻常梭菌的毒性。我们的研究结果表明，MS-Ag-rGO对寻常葡萄球菌的毒性高于水热技术合成的Ag-rGO。抗氧化酶活性的变化，生长参数的减少以及光合色素的数量证实了MS-Ag-rGO对寻常梭菌的毒性。我们的研究结果表明，MS-Ag-rGO对寻常葡萄球菌的毒性高于水热技术合成的Ag-rGO。抗氧化酶活性的变化，生长参数的减少以及光合色素的数量证实了MS-Ag-rGO对寻常梭菌的毒性。我们的研究结果表明，MS-Ag-rGO对寻常葡萄球菌的毒性高于水热技术合成的Ag-rGO。