The biological interactions of graphene have been extensively investigated over the last 10 years. However, very little is known about graphene interactions with the cell surface and how the graphene internalization process is driven and mediated by specific recognition sites at the interface with the cell. In this work, we propose a methodology to investigate direct molecular correlations between the biomolecular corona of graphene and specific cell receptors, showing that key protein recognition motifs, presented on the nanomaterial surface, can engage selectively with specific cell-receptors. We consider the case of apolipoprotein A-I, found to be very abundant in the graphene protein corona, and observe that the uptake of graphene nanoflakes is somewhat increased in cells with greatly elevated expression of scavenger receptors B1, suggesting a possible mechanism of endogenous interaction. The uptake results, obtained by flow cytometry, have been confirmed using Raman microspectroscopic mapping, exploiting the strong Raman signature of graphene.

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.

The use of nanotechnology in the piezoelectric industry conveys new concerns about the environmental toxicity related to lead based nanomaterials. Perovskite structured materials are extensively used as piezoelectrics, lead zirconate titanate (PZT) being the primary choice for sensors, actuators, etc., because of its powerful electromechanical conversion. However, during the life cycle of PZT piezoelectrics lead generally leaches into the environment over time, leading to human exposure and potential environmental hazard. Lead-free bismuth based-ferroelectric materials (BNT-BT) are promising substitutes due to their ability to provide all the piezoelectric attributes without leaching toxic material. Yet, little is known about the potential toxicity and interactions of these nanomaterials with biomolecules and their subsequent intracellular localization at the nanoscale. The aim of this study was to compare the biological impact and uptake of lead and bismuth-based piezoelectric nanoparticles in order to present a suitable substitute for the piezoelectric industry. Our results show that BNT-BT and PZT nanoparticles were internalized through the endolysosomal pathway following a first order kinetic, nanoparticles were localized in the lamellar bodies without inducing cell toxicity measured by mitochondrial activity and cell membrane integrity. Furthermore, BNT-BT nanoparticles were more stable as lead-based PZT released 20% more lead ions into cell culture media. Finally, we propose bismuth-based BNT-BT as a suitable candidate for commercial use as they avoid environmental leaching, imposing less risk during manufacturing and in occupational health, beside the high biocompatibility and similar physico-chemical properties.

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