Abstract
Fresh two-dimensional molybdenum disulfide (MoS2) absorbs the hydrocarbon contaminations in the ambient air and makes surface aging. To understand how the surface aging influences the interactions between MoS2 and biomolecules is important in the biomedical applications. Here, employing all-atom molecular dynamics simulations, we investigated the interactions of the fresh and aged MoS2 nanosheets with the lipid membranes of different components. Our results demonstrate that both the fresh and aged MoS2 nanosheets can spontaneously insert into the bilayer membranes. However, the fresh MoS2 nanosheet displays significantly stronger interaction and then has a larger penetration depth than the aged counterpart, regardless of the lipid components. The calculations of potential mean forces through the umbrella sampling further confirm that the insertion of fresh MoS2 into the lipid membranes is more energetically favorable. Moreover, we found that the fresh MoS2 nanosheet can cause a larger damage to the integrity of lipid membranes than the aged one. This work provides insightful understandings of the surface-aging-dependent interactions of the MoS2 nanosheets with biomembranes, which could facilitate the design of novel MoS2-based nanodevices with advanced surface properties.
Highlights
Molybdenum disulfide (MoS2) is a representative transition metal dichalcogenides and has been recently attracted a significant number of interests in the scientific community
The adsorption of hydrocarbon contaminations during aging process changes the surface properties and affects the interactions between the MoS2 nanosheets and the surroundings, which can be mainly characterized by the water contact angles (WCAs) on the surface
As one of the most important surface properties, the WCA is directly associated with the surface hydrophobicity/hydrophilicity, which is influenced by the adsorption of hydrocarbon contaminations and the possible changes of the termination groups at the outermost MoS2 along the aging process
Summary
Molybdenum disulfide (MoS2) is a representative transition metal dichalcogenides and has been recently attracted a significant number of interests in the scientific community. We employed molecular dynamics (MD) simulations to study how the surface aging process of MoS2 affects its interactions with the lipid membranes of different components, e.g., 1-1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE) and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC). We found that both the MoS2 nanosheets (fresh vs aged) can insert into the lipid membranes, which is dominated by the inter-molecules van der Waals interactions. To describe the free energy changes for the insertions of fresh and aged MoS2 into the lipid membranes, the potential of mean force (PMF) along the Z-direction, which is perpendicular to the membrane surface, were calculated using umbrella sampling. The values of Schain 1, 0.5, and 0 represent perfect alignment, antialignment, and random orientation, respectively (Fu et al, 2020)
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