Molecular dynamics simulations reveal statistics and microscopic mechanisms of water permeation in membrane-embedded artificial water channel nanoconstructs

Abstract

Understanding water transport mechanisms at the nanoscale level remains a challenge for theoretical chemical physics. Major advances in chemical synthesis have allowed us to discover new artificial water channels, rivaling with or even surpassing water conductance and selectivity of natural protein channels. In order to interpret experimental features and understand microscopic determinants for performance improvements, numerical approaches based on all-atom molecular dynamics simulations and enhanced sampling methods have been proposed. In this study, we quantify the influence of microscopic observables, such as channel radius and hydrogen bond connectivity, and of meso-scale features, such as the size of self-assembly blocks, on the permeation rate of a self-assembled nanocrystal-like artificial water channel. Although the absolute permeation rate extrapolated from these simulations is overestimated by one order of magnitude compared to the experimental measurement, the detailed analysis of several observed conductive patterns in large assemblies opens new pathways to scalable membranes with enhanced water conductance for the future design.

Artificial Water Channels Form Precursors to Sponge-Like Aggregates in Water–Ethanol Mixtures

“…We used the force field parameters already tested in previous studies of AWCs in lipid bilayers. , We used the CHARMM general force field (CgenFF) , automatic procedure to assign the nonbonded parameters and partial charges of the ethanol molecule. In coherence with the force field for the solutes and ethanol, we used the TIP3P model for water .…”

“…At this stage, we lack a microscopic view of the aggregation process that leads to the formation of AWCs in PA membranes. In our previous work, we used molecular dynamics (MD) simulations to study the behavior of AWCs in lipid membranes by assuming their crystallographic X-ray structures − as the initial states for the AWCs. Investigation of the aggregation process can provide additional insight into the structures of functional AWCs in membranes without relying on information from the separate X-ray structure.…”

CHARMM-GUI Membrane Builder: Past, Current, and Future Developments and Applications

“…The water permeation is also studied in other artificial water channels made of carbon nanotube or aggregated polymers using MD simulations. For example, Muraoka et al designed a synthetic ion channel with multiblock amphiphiles and the ion permeation is gated by amine ligands (Figure B) .…”

A Water/Ion Separation Device: Theoretical and Numerical Investigation

“…On the other hand, carbonbased materials, such as graphene, are among the most popular choices and have been incorporated for the construction of permeable membranes due to their porous structure and wetting characteristics [15]. Recently, synthetic nano-conduits have been introduced, such as artificial water channels (AWCs), to develop highly selective membranes for water desalination [16]. In a neighboring research field with biological interest, bacterial membrane potential dynamics have been investigated for exploitation in microfluidicbased platforms [17].…”