State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu Province 210023, China.
Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources and International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China.
J Hazard Mater. 2024 Dec 5;480:135972. doi: 10.1016/j.jhazmat.2024.135972. Epub 2024 Sep 26.
Although organic matter (exudate) excreted by aquatic organisms is an important component of dissolved organic matter (DOM) in the natural environment, its potential effects on the bioaccumulation of nanoparticles (NPs) remain unclear. In the present study, we examined the effects of the exudates from the protozoan Tetrahymena thermophila on the bioaccumulation (including uptake and cell surface adsorption) of iron oxide (FeO, polyacrylate coated) and silica (SiO) NPs in T. thermophila. The exudates were mostly (93.6 %, in carbon) composed of < 1-kDa molecules (e.g., lipids). When the exudates were mixed with the NPs, significant adsorption occurred on SiO NPs but not on FeO NPs. Independent of their adsorption by the NPs, the exudates significantly inhibited the bioaccumulation of both SiO NPs and FeO NPs by T. thermophila. This inhibitory effect was shown to be mainly due to their inhibition of NP adsorption on the cell surface. By contrast, the exudates had negligible effects on the uptake of either NP type, most likely due to their low molecular weight. Since DOM in the aquatic environment is dominated by molecules < 1 kDa, the potential effects of low-molecular-weight DOM, such as exudates from aquatic organisms, on the bioaccumulation of NPs merits greater attention. ENVIRONMENTAL IMPLICATION: Nanoparticles (NPs) are hazardous materials widespread in the natural environment. Previous studies showed that dissolved organic matter (DOM) in aquatic environments determine the environmental behavior and ecological effects of NPs. Although organic matter (exudate) excreted by aquatic organisms is an important component of DOM, its potential effects on the bioaccumulation of NPs remain unclear. In the present study, we found that the exudates inhibited the cell-surface adsorption of NPs but had no effects on NP uptake, as different from the well-known effects of DOM on NP bioaccumulation. This finding merits attention during evaluations of the environmental risks of NPs.
虽然水生生物排泄的有机物（渗出物）是自然环境中溶解有机物（DOM）的重要组成部分，但它对纳米颗粒（NPs）生物累积的潜在影响尚不清楚。在本研究中，我们研究了原生动物四膜虫的渗出物对氧化铁（FeO，聚丙烯酸酯涂层）和二氧化硅（SiO）NPs 在四膜虫中的生物累积（包括摄取和细胞表面吸附）的影响。渗出物主要由<1 kDa 的分子（例如脂质）组成，占 93.6%（按碳计）。当渗出物与 NPs 混合时，SiO NPs 发生显著吸附，但 FeO NPs 没有。独立于它们被 NPs 吸附，渗出物显著抑制了 SiO NPs 和 FeO NPs 被四膜虫的生物累积。这种抑制作用主要是由于它们抑制了 NP 在细胞表面的吸附。相比之下，渗出物对两种 NP 类型的摄取几乎没有影响，这很可能是由于其分子量低。由于水生环境中的 DOM 主要由<1 kDa 的分子组成，因此，低分子量 DOM（例如水生生物的渗出物）对 NPs 生物累积的潜在影响值得更多关注。环境意义：纳米颗粒（NPs）是广泛存在于自然环境中的有害物质。先前的研究表明，水生环境中的溶解有机物（DOM）决定了 NPs 的环境行为和生态效应。虽然水生生物排泄的有机物（渗出物）是 DOM 的重要组成部分，但它对 NPs 生物累积的潜在影响尚不清楚。在本研究中，我们发现渗出物抑制了 NPs 的细胞表面吸附，但对 NP 的摄取没有影响，与 DOM 对 NP 生物累积的已知影响不同。在评估 NPs 的环境风险时，这一发现值得关注。
