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Green exfoliation of graphene; an in vitro study of toxicity and biocompatibility
* 1, 2, 3 , 1, 3 , 3, 4 , 3, 5 , 5 , 1, 3 , 3, 4 , 3, 5 , 1, 3 , 2, 3
1  1 Laboratory of Physiology, Faculty of Medicine, University of Ioannina, Ioannina, Greece
2  2 Department of Nephrology, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina, Greece
3  3 Nanomedicine and Nanobiotechnology Research Group, University of Ioannina, Ioannina, Greece
4  4 Department of Materials Science and Engineering, University of Ioannina, Ioannina, Greece
5  5 Laboratory of Biotechnology, Department of Biological Applications and Technologies, University of Ioannina, Ioannina, Greece
Academic Editor: Alfredo Berzal-Herranz (registering DOI)

Due to their unique physicochemical properties, the use of graphene-based nanomaterials in biomedical applications has attracted great interest over the last decade. Nonetheless, evaluation of the biocompatibility of a nanomaterial is a crucial prerequisite before its use in biomedical applications. Recently, green exfoliation methods have emerged as more economical and sustainable approaches for producing graphene from graphite. The aim of this study was to evaluate the toxicity and biocompatibility of graphene that has been synthesized either with chemical or green procedures. In vitro assays were performed against THP-1-derived macrophages. Cytotoxicity was assessed with MTT assay, and examination of the redox stage of cells, evaluation of apoptosis and cell cycle analysis, were performed using Flow cytometry. Chemical graphene’s exfoliation requires the use of toxic solvent DMF, and thus its toxicity assessment was limited to low doses (≤20 μg/mL). At these doses both materials weren’t cytotoxic, however green graphene’s lack of chemicals made it biocompatible even at 10x higher doses. Flow cytometry showed that none of the nanomaterials generated intracellular ROS, induced apoptotic death or cell cycle arrest. While both materials seem to be safe at low doses, green exfoliated- graphene could be used at higher doses. Moreover, it’s sustainable and economical way of production make it an ideal candidate for biomedical applications (i.e., biosensing, drug delivery etc.). Further research on the activation of molecular pathways of inflammation by green graphene could prove its value for use in such applications.

Keywords: graphene; green exfoliation; biocompatibility; toxicity; sustainability; biomedical applications