Toxic Effects and Molecular Mechanism of Different Types of Silver Nanoparticles to the Aquatic Crustacean Daphnia magna

Silver nanoparticles (AgNPs) have been assessed to have a high exposure risk for humans and aquatic organisms. Toxicity varies considerably between different types of AgNPs. This study aimed to investigate the toxic effects of AgNPs with different particle sizes (40 and 110 nm) and different surface coatings (sodium citrate and polyvinylpyrrolidone, PVP) on Daphnia magna and their mechanisms of action. The results revealed that the citrate-coated AgNPs were more toxic than PVP-coated AgNPs and that the 40 nm AgNPs were more toxic than the 110 nm AgNPs. Transcriptome analysis further revealed that the toxic effects of AgNPs on D. magna were related to the mechanisms of ion binding and several metabolic pathways, such as the “RNA polymerase” pathway and the “protein digestion and absorption” pathway. Moreover, the principal component analysis (PAC) results found that surface coating was the major factor that determines the toxicities compared to particle size. These results could help us better understand the possible mechanism of AgNP toxicity in aquatic invertebrates at the transcriptome level and establish an important foundation for revealing the broad impacts of nanoparticles on aquatic environments.

银纳米颗粒（silver nanoparticles, AgNPs）已被评估对人类及水生生物具有较高的暴露风险。不同类型的银纳米颗粒毒性差异显著。本研究旨在探究不同粒径（40 nm与110 nm）、不同表面涂层（柠檬酸钠与聚乙烯吡咯烷酮，PVP）的银纳米颗粒对大型溞（Daphnia magna）的毒性效应及其作用机制。研究结果显示，柠檬酸钠修饰的银纳米颗粒毒性强于PVP修饰的银纳米颗粒，且40 nm粒径的银纳米颗粒毒性高于110 nm粒径的银纳米颗粒。转录组分析进一步揭示，银纳米颗粒对大型溞的毒性效应与离子结合机制及多条代谢通路密切相关，例如"RNA聚合酶"通路与"蛋白质消化吸收"通路。此外，主成分分析（principal component analysis, PAC）结果表明，相较于粒径，表面涂层是决定银纳米颗粒毒性的主要因素。本研究结果有助于在转录组层面更好地理解银纳米颗粒对水生无脊椎动物的潜在毒性机制，并为阐明纳米颗粒对水生环境的广泛影响奠定重要基础。