Unabated use of nanoplastics (<1 μm) in the consumer products and their consequent release to the marine environment poses a substantial threat to the marine ecosystem. The toxic impact of the nanoplastics on marine microalgae is yet to be explored in detail, and the role of reactive oxygen species generation remains largely unclear. The algal exudates constitute a significant part of the natural organics present in the marine system that may readily adsorb over the nanoplastics to form eco-corona. In the current work a marine alga, Chlorella sp., was considered a bioindicator organism and the effects of eco-corona formation in lessening the toxic impact of the nanoplastics was analyzed. Three differently functionalized polystyrene nanoplastics (PS NPs): Aminated (NH₂-PS NPs), Carboxylated (COOH-PS NPs) and Plain nanoplastics were aged (12, 24, and 48 h) in the EPS containing medium to facilitate eco-corona formation. Decline in cell viability, membrane integrity, and photosynthetic yield were considered to be principle toxicity indicators. The role of oxidative stress as key mode of action (MOA) was studied considering generation of overall reactive oxygen species, and specific radicals (hydroxyl and superoxide) as relevant markers. The changes in antioxidant enzyme activities (superoxide dismutase, and catalase) were also measured. The results clearly indicate a significant decline in the oxidative stress and corresponding lessening of the toxic effects due to eco-corona formation on the PS NPs. The response varied with surface charge on the NPs and ageing duration. Considering the increasing importance of the nanoplastics as one of the major emerging pollutants in marine ecosystem, this study strongly suggests that the EPS mediated eco-corona formation may substantially lessen their toxic burden.

消费产品中毫不减退地使用纳米塑料（<1μm）及其随后释放到海洋环境中，对海洋生态系统构成了重大威胁。纳米塑料对海洋微藻的毒性影响尚待详细探讨，而活性氧的产生作用仍不清楚。藻类渗出液构成了海洋系统中天然有机物的重要组成部分，这些有机物很容易吸附在纳米塑料上以形成生态电晕。在当前的工作中，海藻小球藻（Chlorella sp。）被视为生物指示生物，并且分析了电晕形成在减轻纳米塑料毒性影响方面的作用。三种功能不同的聚苯乙烯纳米塑料（PS NP）：胺化（NH ₂-PS NPs，羧化（COOH-PS NPs）和普通纳米塑料在含EPS的培养基中老化（12、24和48 h），以促进生态电晕的形成。细胞活力，膜完整性和光合产量的下降被认为是主要的毒性指标。考虑到总活性氧的产生以及特定自由基（羟基和超氧化物）作为相关标记，研究了氧化应激作为关键作用方式（MOA）的作用。还测量了抗氧化酶活性（超氧化物歧化酶和过氧化氢酶）的变化。结果清楚地表明，由于在PS NP上形成了生态电晕，氧化应激显着下降，并相应减少了毒性作用。响应随NP上的表面电荷和老化时间而变化。