Gold engineered nanoparticles (nAu) are increasingly detected in ecosystems, and this raises the need to establish their potential effects on aquatic organisms. Herein, cytotoxic and genotoxic effects of branched polyethylenimine (BPEI)- and citrate (cit)-coated nAu (5, 20, and 40 nm) on algae Pseudokirchneriella subcapitata were evaluated. The apical biological endpoints: growth inhibition and chlorophyll a (Chl a) content were investigated at 62.5–1000 µg/L over 168 h. In addition, the apurinic/apyrimidinic (AP) sites, randomly amplified polymorphic deoxyribonucleic acid (RAPD) profiles, and genomic template stability (GTS) were assessed to determine the genotoxic effects of nAu. The results show algal growth inhibition at 5 nm BPEI-nAu up to 96 h, and thereafter cell recovery except at the highest concentration of 1000 µg/L. Insignificant growth reduction for cit-nAu (all sizes), as well as 20 and 40 nm BPEI-nAu, was observed over 96 h, but growth promotion was apparent at all exposures thereafter except for 40 nm BPEI-nAu at 250 µg/L. A decrease in Chl a content following exposure to 5 nm BPEI-nAu at 1000 µg/L corresponded to significant algal growth reduction. In genotoxicity studies, a significant increase in AP sites content was observed relative to the control – an indication of nAu ability to induce genotoxic effects irrespective of their size and coating type. For 5 nm- and 20 nm-sized nAu for both coating types and exposure concentrations no differences in AP sites content were observed after 72 and 168 h. However, a significant reduction in AP sites was observed following algae exposure to 40 nm-sized nAu (irrespective of coating type and exposure concentration) at 168 h compared to 72 h. Thus, AP sites results at 40 nm-size suggest likely DNA damage recovery over a longer exposure period. The findings on AP sites content showed a good correlation with an increase in genome template stability and growth promotion observed after 168 h. In addition, RAPD profiles demonstrated that nAu can induce DNA damage and/or DNA mutation to P. subcapitata as evidenced by the appearance and/or disappearance of normal bands compared to the controls. Therefore, genotoxicity results revealed significant toxicity of nAu to algae at the molecular level although no apparent effects were detectable at the morphological level. Overall, findings herein indicate that long-term exposure of P. subcapitata to low concentrations of nAu may cause undesirable sub-lethal ecological effects.

黄金工程纳米颗粒（nAu）在生态系统中越来越多地被发现，这增加了确定其对水生生物潜在影响的需求。在此，支链聚乙烯亚胺（BPEI）的细胞毒性和基因毒性作用-和柠檬酸（CIT）上包被的藻类NAU（5，20和40 nm）的门Pseudokirchneriella subcapitata进行了评价。根尖的生物学终点：生长抑制和叶绿素a（Chl a168小时内，其含量为62.5–1000 µg / L。此外，评估了嘌呤/嘧啶（AP）位点，随机扩增的多态性脱氧核糖核酸（RAPD）图谱和基因组模板稳定性（GTS），以确定nAu的遗传毒性作用。结果显示，在长达96 h的5 nm BPEI-nAu处，藻类生长受到抑制，此后细胞恢复，但最高浓度为1000 µg / L。在96小时内观察到cit-nAu（所有尺寸）以及20和40 nm BPEI-nAu的生长均无明显减少，但此后所有暴露下均明显促进了生长，除了250 µg / L的40 nm BPEI-nAu以外。Chl a减少在1000 µg / L的5 nm BPEI-nAu中暴露后，藻类的含量对应于藻类生长的显着减少。在遗传毒性研究中，观察到AP位点含量相对于对照显着增加-指示nAu诱导遗传毒性作用的能力，无论其大小和涂层类型如何。对于5 nm和20 nm大小的nAu，无论是涂层类型还是暴露浓度，在72和168小时后，AP位点含量均未观察到差异。但是，藻类在168 h暴露于40 nm大小的nAu（与涂层类型和暴露浓度无关）后，与72 h相比，AP位点显着减少。因此，AP位点在40 nm大小处的结果表明，在更长的暴露时间内可能会恢复DNA损伤。AP位点含量的发现与168小时后观察到的基因组模板稳定性的增加和生长促进具有良好的相关性。此外，RAPD图谱表明，nAu可以诱导DNA损伤和/或DNA突变，从而与正常对照组相比，正常条带的出现和/或消失证明了亚次要P. capitata。因此，遗传毒性结果显示，尽管在形态学水平上未检测到明显的作用，但在分子水平上nAu对藻类具有明显的毒性。总的来说，发现本文表明，长期接触P. subcapitata低浓度NAU的可能导致不期望的亚致死生态效应。