Systematic Assessment of the Toxicity and Potential Mechanism of Graphene Derivatives In Vitro and In Vivo

Graphene is a two-dimensional crystal that is stripped from pristine graphite and made of single layer of carbon atoms. Containing numerous functional groups, graphene derivatives (GDs) could be easily modified and have aroused great attention for potential applications in biomedicine. However, pristine graphene and graphene oxide (GO) could arouse cell and animal toxicity. To screen GDs with high biocompatibility applied for biomedicine, general comparison was performed about the toxicities of six GDs with diverse types of surface modification, size, and redox state, including GO, reduced GO (rGO), graphene quantum dot (GQD), aminated GQD (GQD-NH2), carboxyl GQD (GQD-COOH), and graphene oxide quantum dot (GOQD). In contrast, it was found that large particle size, oxidation state, high concentration, and long exposure time were unfavorable factors affecting the cell viability. We further explored the mechanism of different toxicity, which could be contribute to cell membrane destruction by sharpened edges of GDs (LDH release, hemolysis), ROS production, immuno-inflammatory responses, and activation of apoptotic pathways (IKK/IB/NF-B and BAX/BCL-2). Overall, our combined data primarily explored the related biochemical and molecular mechanism underlying the biological behaviors and toxicity of GDs, and we also identified GQD, GQD-NH2, GQD-COOH, and GOQD could be safely used for biomedical application as drug carriers.