Kaolin Alleviates Graphene Oxide Toxicity

Abstract

With increased interest in the practical use of graphene-based materials, concerns about the remediation of the environmental nanotoxicity of graphene and graphene-related materials have grown. In this study, we report that kaolin nanoclay significantly alleviates the toxicity of graphene oxide in aqueous environments. We employed the Paramecium caudatum protozoan to demonstrate the effects of equal concentrations of kaolin on the remediation of graphene oxide toxicity on survival and growth rates, chemotaxis, galvanotaxis, DNA complexation, and food vacuole formation. Importantly, the toxicity of graphene oxide coagulated with kaolin is reduced without the aggregated particles being removed from the environment.

Kaolin alleviates the toxicity of graphene oxide for mammalian cells

“…We found that sizes of the individual nanoparticles corresponded well to those reported earlier. 37 Nanoparticles formed well-dispersed aggregates, which could be visualized using dark-field (DF) microscopy ( Fig. 1).…”

“…The decrease in graphene toxicity even when high levels of kaolin and graphene are used coincides with the results obtained earlier. 37 There are conflicting data on the effect of graphene oxide on the viability of living organisms. 34,[46][47][48] We believe that different biological entities vary in their susceptibility to graphene oxide, so we decided to assess the effect of graphene oxide, kaolin and their combined effect on the induction of apoptosis in primary cells.…”

“…One of the probable mechanisms of alleviated graphene oxide toxic-ity in the presence of kaolin could be the sorption of graphene oxide nanosheets by kaolin plates as was proposed earlier. 37 Such sorption can decrease graphene oxide uptake by cells or prevent graphene oxide induced ROS formation in the media or inside the cells.…”

“…However, using atomic force microscopy and sedimentation analysis, earlier it was clearly demonstrated that planar kaolin nanoparticles strongly aggregated with graphene oxide plates in an aqueous medium. 37 Kaolin coagulated with graphene oxide in water, forming relatively large conglomerates, which resulted in the reduced negative effects of graphene oxide to ciliate protozoan Paramecium caudatum. 37 Moreover, kaolinite demonstrated better sorption properties towards graphene oxide (compared to montmorillonite or illite) and inhibited the transport of graphene oxide in saturated porous media.…”

Organic-nanoclay composite materials as removal agents for environmental decontamination

“…55 However, atomic force microscopy was successfully used to demonstrate that planar kaolin nanoparticles strongly aggregate with graphene oxide plates. 56 Thus, for the rst time, the authors of this work 56 describe a signicant reduction in the toxicity of graphene oxide plates using planar kaolin nanoclay in an aqueous medium. Using atomic force microscopy, it has been shown that kaolin coagulates with graphene oxide in water, forming relatively large conglomerates, which reduces the side negative effects of graphene oxide on P. caudatum ciliates, which potentially has high practical signicance in the eld of graphene materials.…”