Autophagy in RAW264.7 Cells Treated with Surface-Functionalized Graphene Oxides

Abstract

This study investigated cytotoxicity, particularly autophagy, in RAW264.7 cells exposed to graphene oxide (GO) and its derivatives (dodecylamine-GO (DA-GO), reduced GO (rGO), and sodium dodecyl sulfate-rGO (SDS-rGO)). Appearance of amine stretching bands, out-of-plane C-H stretching vibrations, and S=O stretching bands in infrared spectra indicated the formation of DA-GO, rGO, and SDS-rGO, respectively. Light microscopy and microculture tetrazolium assay showed that all the GO types exerted cytotoxic effects on RAW264.7 cells in a concentration-dependent manner. Higher concentrations of the GO types downregulated the expression of PU.1, a unique transcription factor in monocytes and macrophages, and decreased the conversion of LC3A/B-I to LC3A/B-II, suggesting that PU.1 was associated with autophagy in RAW264.7 cells. These results suggested that surface-functionalized GOs exerted cytotoxic effects in a concentration-dependent manner by changing the expression of critical genes and inducing autophagy in macrophages.