▎ 摘　　要

Previous studies reported that the differences in the toxicity of reduced graphene oxide (rGO) modified by metal nanoparticles (NPs) were mainly caused by the released metal ions, while the impact of cell surface properties and rGO nanocomposites characteristics on the toxic effects have seldom been taken into consideration. In this study, we investigated the toxicities of six rGO nanocomposites (rGO-Au, rGO-Ag, rGO-Pd, rGO-Fe3O4, rGO-Co3O4, rGO-SnO2) in two algae (Scenedesmus obliquus and Chlamydomonas reinhardni) with the aim of evaluating the role of surface properties on the different toxic effects. Results showed that C. reinhardni was sensitive to the rGO nanocomposite, but no obvious adverse effect was observed in S. obliquus. Moreover, different rGO nanocomposites showed various toxic effects in C. reinhardni. Properties including algal cell surface and rGO nano-composites were then characterized. Cells with abundant functional groups and hydrophobic surfaces exhibited more metal adsorption and interactions with the nanomaterials. In addition, heterointerfaces and released ions from rGO nanocomposites triggered various toxicities by interfering with the interactions with algal cells. However, algal surface properties were the main factors determining the different toxic effects between algal species. This study emphasizes the importance of surface properties in the process of toxicity evaluation. (C) 2020 Elsevier Ltd. All rights reserved.