In vitro and environmental toxicity of reduced graphene oxide as an additive in automotive lubricants

Despite the ground-breaking potential of nanomaterials, their safe and sustainable incorporation into an array of industrial markets prompts a deep and clear understanding of their potential toxicity for both humans and the environment. Among the many materials with great potential, graphene has shown promise in a variety of applications; however, the impact of graphene based products on living systems remains poorly understood. In this paper, we illustrate that via exploiting the tribological properties of graphene nanosheets, we can successfully improve both the frictional behaviour and the anti-wear capacity of lubricant oil for mechanical transmission. By virtue of reducing friction and enhancing lubricant lifetimes, we can forecast a reduction in friction based energy loss, in addition to a decrease in the carbon footprint of vehicles. The aforementioned positive environmental impact is further strengthened considering the lack of acute toxicity found in our extensive in vitro investigation, in which both eukaryotic and prokaryotic cells were tested. Collectively, our body of work suggests that by the use of safe nanoadditives we could contribute to reducing the environmental impact of transportation and therein take a positive step towards a more sustainable automotive sector. The workflow proposed here for the evaluation of human and environmental toxicity will allow for the study of nanosized bare graphene material and can be broadly applied to the translation of graphene-based nanomaterials into the market.