Nanoconfined water can orient and cause long-range dipolar interactions with biomolecules

Abstract

Surface properties are generally determined by the top most surface layer also defining how molecules adsorb onto it. By exploring effects due to interactions with deeper subsurface layers, however, long-range interaction forces were found to also significantly contribute to molecular adsorption, in which hydration of the subsurface region is the key factor. Water molecules confined to a subsurface amphiphilic gradient are confirmed to cause these long-range dipolar interactions by preferential orientation, thus significantly changing the way how a protein interacts with the surface. These findings imply future exploitation of an additional factor to modulate adsorption processes.

Effects of the Chemical and Structural Properties of Silane Monolayers on the Organization of Water Molecules and Ions at Interfaces, from Molecular Dynamics Simulations

“…In the absence of a dipole field, and if the intermolecular distance is below 5 Å, water molecules can organize themselves into a tetrahedral network due to hydrogen-bond interactions. 3 In crystalline ice, a welldefined tetrahedral network appears, while in bulk water, only a short-range order remains. 48 Also, from the analysis of the water−water angle distribution, water molecules in the vicinity of hydrophobic surfaces were shown to exhibit a higher order than in the bulk.…”

“…This gradient is at the origin of long-range dipolar interactions governing the protein interactions with the surface. 3 Other examples show that the hydration layer plays a decisive role in the adsorption of peptides, 4 proteins, 5 DNA, 6 or RNA. 7 Owing to the crucial role of the hydration layer, several authors have focused on understanding the effect of surface chemistry, and of the surface structure, on the hydration layer.…”

Low pressure plasma modifications for the generation of hydrophobic coatings for biomaterials applications

“…Elsewhere, in vitro multiple protein adsorption tests demonstrated that the pre‐adsorbed albumin on siloxane surface could not be displaced by fibrinogen or immunoglobulin because of the small size and tenacious binding of albumins to siloxane surfaces . Recent studies albumin binding to hydration stratified pp matrix (50 nm of a silica‐like hydrophilic base layer with the dosed addition of O 2 gas, followed by a hydrophobic cover layer of HMDSO pp of varying thickness) have shown that nano‐confined hydration of the deeper silica‐like sub‐surface layers also influenced the albumin adsorption and related conformation …”

Plasma polymerization of hexamethyldisiloxane: Revisited

“…[ 30,32,33 ] Recently, nm‐thick HMDSO‐derived PPFs have been applied as surface chemistry‐defining cover layers to gain new insights into protein and bacteria adhesion. [ 34,35 ] Noteworthy, water intrusion was found to affect biomolecule adsorption, whereas the mechanical properties of the substrate material appeared to be of less importance. Furthermore, HMDSO plasma‐modified hydrogels allow for the controlled release of drugs.…”