Physico-chemical properties based differential toxicity of graphene oxide/reduced graphene oxide in human lung cells mediated through oxidative stress.

Sandeep Mittal,Renu Pasricha,Nitesh Dhiman,Lalit Kumar Singh Chauhan,Alok Kumar Pandey,Veeresh Kumar

doi:10.1038/srep39548

Abstract

Goraphene derivatives (GD) are currently being evaluated for technological and biomedical applications owing to their unique physico-chemical properties over other carbon allotrope such as carbon nanotubes (CNTs). But, the possible association of their properties with underlying in vitro effects have not fully examined. Here, we assessed the comparative interaction of three GD - graphene oxide (GO), thermally reduced GO (TRGO) and chemically reduced GO (CRGO), which significantly differ in their lateral size and functional groups density, with phenotypically different human lung cells; bronchial epithelial cells (BEAS-2B) and alveolar epithelial cells (A549). The cellular studies demonstrate that GD significantly ineternalize and induce oxidative stress mediated cytotoxicity in both cells. The toxicity intensity was in line with the reduced lateral size and increased functional groups revealed more toxicity potential of TRGO and GO respectively. Further, A549 cells showed more susceptibility than BEAS-2B which reflected cell type dependent differential cellular response. Molecular studies revealed that GD induced differential cell death mechanism which was efficiently prevented by their respective inhibitors. This is prior study to the best of our knowledge involving TRGO for its safety evaluation which provided invaluable information and new opportunities for GD based biomedical applications.

Highlights

Graphene derivatives (GD) are currently being evaluated for technological and biomedical applications owing to their unique physico-chemical properties over other carbon allotrope such as carbon nanotubes (CNTs)
The results revealed that all the samples were planar in shape and reduction of the graphene oxide (GO) further reduces the dimension of graphitic planes as shown for thermally reduced GO (TRGO) and chemically reduced GO (CRGO) (Fig. 1a)
TRGO was having smaller graphite plane ranged from 50 nm to 250 nm compared to CRGO that could be due to the sudden exfoliation of graphite sheets and removal of functional groups at higher temperature

Summary

Introduction

Graphene derivatives (GD) are currently being evaluated for technological and biomedical applications owing to their unique physico-chemical properties over other carbon allotrope such as carbon nanotubes (CNTs). Molecular studies revealed that GD induced differential cell death mechanism which was efficiently prevented by their respective inhibitors This is prior study to the best of our knowledge involving TRGO for its safety evaluation which provided invaluable information and new opportunities for GD based biomedical applications. Based on above reports it is not possible to draw a conclusion regarding their biosafety and safer use in biomedical applications This discrepancy could be due to the fact that the unique physico-chemical properties of NMs can actively interfere or manipulate biological systems as demonstrate for CNTs23. There is dearth of information regarding how the lateral dimension and functional groups of different GD dictate their differential in vitro behavior and the underlying molecular mechanism is still unknown Such information is necessary to avoid generalization and description of all GD as being toxic to human and environmental health[24]

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