Antibacterial pathway of MoS2 nanosheets against Escherichia coli membrane via phospholipid extraction and localized phase transition.

Abstract

The rapid emergence of antimicrobial resistance among pathogens have stimulated the quest for new generation antibacterials with minimal resistance inducing capabilities such as nanomaterials. Two-dimensional molybdenum disulfide (MoS2), a transition metal chalcogenide, has recently been recognized to exhibit excellent broad-spectrum bactericidal efficiency. However, a detailed assessment of the molecular level interactions responsible for their antibacterial action is imperative to modulate their efficacy. Through an atomistic molecular dynamics study, the present study delineates the interactions happening at the nano-bio interface responsible for their antibacterial action against Escherichia coli (E. coli) membrane [Soft Matter, 2022, 18,7159-7170]. The study conveys a two-step pathway of MoS2 nanosheet interactions with the bacterial membrane; (i) spontaneous phospholipid extraction by the nanosheet via van der Waals interactions with lipid acyl tails followed by (ii) complete ingestion of the nanosheet in the bilayer hydrophobic core through a synergic effect of MoS2-lipid interactions and lipid-lipid self-interactions. The phospholipid extraction to the MoS2 surface originates cavity formation in the extracellular leaflet which in turn creates a water passage across the membrane, signifying the possibility of cytoplasmic leakage in realistic membranes. Further, on complete insertion in the bilayer, the nanosheet induces the formation of densely packed lipid layers in its vicinity and causes localized phase transition in the membrane. These structural deteriorations in the bacterial membrane can be escalated by increasing the size of the nanosheet as well as by increasing the nanosheet concentrations. Thus, the study outlines both phospholipid extraction as well as localized alterations in membrane morphology responsible for the antibacterial activity of MoS2 nanosheets against E. coli bacterial membrane.