A comparative study on cytotoxicity of different types of commercial single- and few-layer graphenes on human monocytes and macrophages

Few-layer graphene (FLG) were prepared via liquid phase exfoliation using surfactants like polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), or sodium deoxycholate (SDC). Alternatively, surfactant-free graphene water dispersions were obtained by oxidizing graphenide ( i.e ., KC 8 ) in tetrahydrofuran, mixing with water, and evaporating the solvent to yield single-layer (SLG). Immune cells are the first responders to exogenous materials, rapidly initiate immune responses, but little is known about the immune effects of commercialized FLG and SLG. This study aims to compare the impact of one SLG and three FLG on THP-1 monocytes and derived macrophages in terms of viability, apoptosis, and reactive oxygen species (ROS) generation. While no significant effects were observed on monocytes, the three FLG dose-dependently reduced macrophage viability, while no effects were observed for SLG. To further investigate the cellular interactions, transmission electron microscopy and scanning electron microscopy confirmed the uptake of FLG/PVA, FLG/SDC, and SLG, and their membrane interactions with macrophages. All three types of FLG increased IL-8 secretion in monocytes and slightly increased IL-1β secretion in macrophages and CD14 expression in monocytes, at 50 μg/mL (the maximum dose tested). FLG/SDC was found to reduce CD163 and CD206 expression in macrophages. SLG exposure (up to 50 μg/mL) caused no significant immune activation. Overall, FLG and SLG exhibited low toxicity, although the three kinds of FLG triggered little immune activation and the production of IL-8 by THP-1 monocytes.