Transport at Nanoscale Interfaces Laboratory

Release of graphene-related materials from epoxy-based composites: characterization, quantification and hazard assessment in vitro

Netkueakul W,   Korejwo D,   Hammer T,   Chortarea S,   Rupper P,   Braun O,   Calame M,   Rothen-Rutishauser B,    Buerki-Thurnherr T,   Wick  P and  Wang J

Nanoscale, (2020)

https://doi.org/10.1039/C9NR10245K

Abstract
Due to their mechanical strength, thermal stability and electrical conductivity, graphene-related materials (GRMs) have been extensively explored for various applications. Moreover, GRMs have been studied and applied as fillers in polymer composite manufacturing to enhance polymer performance. With the foreseen growth in GRMs production, occupational and consumer exposure is inevitable, thus raising concerns for potential health risks. Therefore, this study aims 1) to characterize aerosol particles released after mechanical abrasion on GRM-reinforced epoxy composites, 2) to quantify the amounts of protruding and free-standing GRMs in the abraded particles and 3) to assess potential effects of the pristine GRMs as well as the abraded particles on human macrophages differentiated from the THP-1 cell line in vitro. GRMs used in this study included graphene nanoplatelets (GNPs), graphene oxide (GO), and reduced graphene oxide (rGO). All types of pristine GRMs tested induced a dose-dependent increase in reactive oxygen species formation, but a decrease in cell viability was only detected for large GNPs at high concentrations (20 and 40 μg/mL). The particle modes measured by the scanning mobility particle sizer (SMPS) were 300-400 nm and by the aerodynamic particle sizer (APS) were between 2-3 µm, indicating the release of respirable particles. A significant fraction (51% to 92%) of the GRMs embedded in the epoxy composites were released in the form of free-standing or protruding GRMs in the abraded particles. The abraded particles did not induce any acute cytotoxic effects.