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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Recent experiments have reported that the fragment of viral protein R (Vpr), Vpr13-33, can assemble and change its conformation after adsorbed on graphene oxide (GO) and then reduce its cytotoxicity. This discovery is of great importance, since the mutation of Vpr13-33 can decrease the viral replication, viral load and delay the disease progression. However, the interactions between Vpr13-33 and GO at atomic level are still unclear. In this study, we performed molecular dynamics simulation to investigate the dynamic process of the adsorption of Vpr13-33 onto GO and the conformation change after aggregating on GO surface. We found that Vpr13-33 was adsorbed on GO surface very quickly and lost its secondary structure. The conformation of peptides-GO complex was highly stable because of π-π stacking and electrostatic interactions. When two peptides aggregated on GO, they did not dimerize, since the interactions between the two peptides were much weaker than those between each peptide and GO.

Noble gases seem to have no significant effect on the anesthetic targets due to their simple, spherical shape. However, xenon has strong narcotic efficacy and can be used clinically, while other noble gases cannot. The mechanism remains unclear. Here, we performed molecular dynamics simulations on phospholipid bilayers with four kinds of noble gases to elucidate the difference of their effects on the membrane. Our results showed that the sequence of effects on membrane exerted by noble gases from weak to strong was Ne, Ar, Kr and Xe, the same order as their relative narcotic potencies as well as their lipid/water partition percentages. Compared with the other three kinds of noble gases, more xenon molecules were distributed between the lipid tails and headgroups, resulting in membrane’s lateral expansion and lipid tail disorder. It may contribute to xenon’s strong anesthetic potency. The results are well consistent with the membrane mediated mechanism of general anesthesia.

Carbon nanotubes (CNTs) have been regarded as one of the most hopeful candidates for transporting drugs to target cells because of their huge surface area, hollow structure, and enhanced cellular uptake. The idea of using their hollow channels as containers to load and unload small drug molecules has been proposed for many years. However, the encapsulation of drugs into CNTs, the internalization of CNT-drug conjugates in the cell membrane, and the successive drug release at the atomic level remain unclear. In this work, we performed molecular dynamics simulations to investigate the potential application of CNTs as a nanocarrier to transport and deliver drug molecules. Pregabalin (PRE) was selected as a model drug, as its size and polarity are suitable for transporting through CNT hollow channels. The simulation can be divided into three stages. First, PRE was encapsulated into the optimized CNT in the water solution and the PRE–CNT complex was formed, then this complex readily entered the lipid bilayer and finally PRE released one by one from CNTs into the membrane. Compared with the direct insertion of PRE in the membrane, the PRE–CNT complex can reduce the energy barrier to enter the membrane and pass the bilayer center. The fast release of PRE from CNTs benefits from its amphipathicity. The electrostatic interaction between its polar groups and lipid headgroups pull the PRE molecules out of the CNT. The results indicate that both the loading and unloading of PRE based on CNTs are energetically favorable. CNTs exhibit great potential as nanovehicles to carry and deliver particular drug molecules.