Interaction of Graphene and its Oxide with Lipid Membrane: A Molecular Dynamics Simulation Study

Abstract

Graphene nanosheet has exhibited an increasing prospect in various biomedical applications because of its extraordinary properties. Meanwhile, recent experiments have shown that graphene has antibacterial activity or cytotoxicity and can cause cell membrane damage. Therefore, it is necessary to understand the interactions between graphene and cell membrane to avoid its adverse effects. Here, we use molecular dynamics simulation to explore these interactions. The results show that pristine graphene (PG) can readily penetrate into the bilayer and has no effect on the integrity of membrane. When graphene oxide (GO) is embedded in the membrane, several lipids are pulled out of the membrane to the surface of GO, resulting in the pore formation and water molecules flowing into the membrane. The difference between PG and GO in the membrane originates from GO's oxygen-contained groups, which enhance the adsorption of the lipids on GO surface. However, the main interactions between GO and membrane are still determined by the strong dispersion interactions between its hydrophobic domains and the lipid tails of the bilayer. Therefore, the toxicity of coated GO can be weakened, since its hydrophobic domains are screened by polymers. The findings may offer new perspective for better designing GO based nanocarrier or antibiotics and other biomedical applications.

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“…Experimentally, three different stages are noted in the lipid membrane degradation process when bacterial cells are treated with GO nanosheets (Figure b) . Molecular dynamics simulation shows the vigorous extraction of phospholipid molecules from lipid membrane (outer membrane modeled by pure 1‐palmitoyl‐2‐oleoyl‐phosphatidylethanolamine) to the graphene nanosheets (Figure c); subsequent theoretical studies further confirm a similar lipid pull out/extraction effect of GO/graphene nanosheets . In the lipid extraction process, van der Waals interaction is the main driving force at first, after which, hydrophobic interactions play a dominant role in the second step.…”

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“…The possibility of stably coating mono-and few-layer graphene sheets in aqueous solution with uniform phospholipid monolayers has been demonstrated both theoretically with molecular dynamics simulations [19,20], and experimentally for both pristine graphene [15] and reduced 100 graphene oxide [16,17]. Lipid-coating of carbon nanotubes has also been shown [21][22][23].…”