We study the properties of the interface of water and the surfactant Hexaethylene Glycol Monododecyl Ether (C12E6)<br>with a combination of Heterodyne-Detected Vibrational Sum Frequency Generation (HD-VSFG), Kelvin-Probe measurements, and Molecular Dynamics (MD) simulations. We observe that the addition of C12E6 close to the critical micelle concentration (CMC), induces a drastic hydrogen bond strength enhancement of the water molecules close to the interface, as well as a flip in their net orientation. The mutual orientation of the water and C12E6 molecules, leads to the emergence of a broad (~ 3 nm) interface with a large electric field of ~ 1V/nm, as evidenced by the Kelvin-Probe measurements and MD simulations. Our findings may open the door for the design of novel electric-field tuned catalytic and light harvesting systems anchored at water-surfactant air interface.
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<p>Understanding the physical and chemical properties of viral infection at molecular scales is a major challenge of the scientific community in the fight against the Coronavirus (COVID-19) pandemic. We employ all-atoms molecular dynamics simulations to study the interaction between the receptor-binding domain of the SARS-CoV-2 spike protein and the surfactant lecithin in water solutions. Our microsecond simulations reveal a preferential binding of lecithin to the receptor-binding motif (RBM) of SARS-CoV-2. Furthermore, we find that the lecitin-RBM binding events are mainly dominated by the hydrophobic interactions, which are accompanied by dewetting of water molecules near the RBM. These proof-of-concept simulations provide a demonstration of the use of biodegradable phospholipids as blockers of binding of SARS-CoV-2 with the human Angiotensin-Converting Enzyme 2 (ACE2) receptor.</p>
<div><div><div><p>Understanding the physical and chemical properties of viral infections at molecular scales is a major challenge for the scientific community more so with the outbreak of global pandemics. There is currently a lot of effort being placed in identifying molecules that could act as putative drugs or blockers of viral molecules. In this work, we computationally explore the importance in antiviral activity of a less studied class of molecules, namely surfactants. We employ all-atoms molecular dynamics simulations to study the interaction between the receptor-binding domain of the SARS-CoV-2 spike protein and the phospholipid lecithin (POPC), in water. Our microsecond simulations show a preferential binding of lecithin to the receptor-binding motif of SARS-CoV-2 with binding energies significantly larger than kBT. Furthermore, hydrophobic interactions in- volving lecithin non-polar tails dominate these binding events, which are also accompanied by dewetting of the receptor binding motif. Through an analysis of fluctuations in the radius of gyra- tion of the receptor-binding domains, its contact maps with lecithin molecules, and distributions of water molecules near the binding region, we elucidate molecular interactions that may play an important role in interactions involving surfactant-type molecules and viruses. We discuss our minimal computational model in the context of lecithin-based liposomal nasal sprays as putative mitigating therapies for COVID-19.</p></div></div></div>
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