Reduced graphene oxide induces cytotoxicity and inhibits photosynthetic performance of the green alga Scenedesmus obliquus.
Increased use of graphene materials might ultimately lead to their release into the environment. However, only a few studies have investigated the impact of graphene-based materials on green plants. In this study, the impact of reduced graphene oxide (RGO) on the microalgae Scenedesmus obliquus was evaluated to determine its phytotoxicity. Treatment with RGO suppressed the growth of the microalgae. The 72-h IC50values of RGO evaluated using the logistic and Gompertz models were 148 and 151 mg L-1, respectively. RGO significantly inhibited Chl a and Chl a/b levels in the algal cells. Chlorophyll a fluorescence analysis showed that RGO significantly down-regulated photosystem II activity. The mechanism of how RGO inhibited algal growth and photosynthetic performance was determined by analyzing the alterations in ultrastructural morphology. RGO adhered to the algal cell surface as a semitranslucent coating. Cell wall damage and membrane integrity loss occurred in the treated cells. Moreover, nuclear chromatin clumping and starch grain number increase were noted. These changes might be attributed to the increase in malondialdehyde and reactive oxygen species levels, which might have exceeded the scavenging ability of antioxidant enzymes (including peroxidase and superoxide dismutase). RGO impaired the extra- and intra-cellular morphology and increased oxidative stress and thus inhibited algal growth and photosynthesis.
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China. Electronic address: dushaoting@zjgsu.edu.cn.
Shaoting
S
Du
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China.
Peng
P
Zhang
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China.
Ranran
R
Zhang
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China.
Qi
Q
Lu
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China.
Lin
L
Liu
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China.
Xiaowei
X
Bao
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang Province, China. Electronic address: lhj@zjgsu.edu.cn.
Huijun
H
Liu
D000975:Antioxidants / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D005453:Fluorescence; D006108:Graphite / Q000737:chemistry / Q000633:toxicity*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D010087:Oxides / Q000737:chemistry; D010544:Peroxidases / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D044444:Scenedesmus / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D010087:Oxides; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D006108:Graphite; D010544:Peroxidases; D013482:Superoxide Dismutase
Chlorophyll a fluorescence; Graphene family; Phytotoxicity; Reduced graphene oxide; Scenedesmus obliquus