Role of Interfacial Water in Protein Adsorption onto Polymer Brushes as Studied by SFG Spectroscopy and QCM

Abstract

The adsorption of large biomolecules such as proteins is of high relevance in medicine; adsorbed proteins can initiate undesirable biological reactions such as blood coagulation or immune responses, which adversely affect the human body and the functioning of medical devices. Thus, the suppression of protein adsorption onto material surfaces is essential for medical and biomedical applications. Interfacial water molecules may play a key role in protein adsorption. In this context, in this study, we prepare various types of surfaces (hydrophobic, hydrophilic, anionic, cationic, and zwitterionic) using polymer brushes with different molecular structures. We analyze the adsorption of negatively and positively charged proteins using a quartz crystal microbalance (QCM) to quantitatively investigate protein adsorption onto the polymer brush surfaces. The structure of the interface between the polymer brushes and water media is investigated using sum frequency generation (SFG) spectroscopy. Our comparison of the protein adsorption characteristics with the properties of the interfacial water molecules of each polymer brush indicates that the interfacial water molecules, which strongly interact with polymer brushes, are important for suppressing protein adsorption. The findings can significantly contribute to the functional biomaterial design.

Decoding the molecular water structure at complex interfaces through surface-specific spectroscopy of the water bending mode

“…So far, surface-specific techniques such as scanning probe microscopy, X-ray spectroscopy, attenuated total reflection-infrared (ATR-IR), and sum-frequency generation (SFG) spectroscopy have been used for investigating the molecular structure and dynamics of water at interfaces. 1 Among them, vibrational SFG spectroscopy has been demonstrated to be a powerful technique to probe the interfacial water molecules at soft (biomolecule-water) [2][3][4][5][6][7] and buried (solid-water) interfaces. [8][9][10][11][12][13][14][15][16][17] SFG spectroscopy is active only in the centrosymmetry-broken region and therefore probes those molecular responses with a non-zero net transition dipole moment along the surface normal direction.…”

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth

“…Water molecules may compete for hydrogen bonding opportunities with both the protein and surface, thereby suppressing protein adsorption. 21,22 On the other hand, dehydration of hydrophobic regions on the protein or substrate is thermodynamically favourable due to the increased entropy of the displaced waters. This serves to promote protein adsorption, especially for globular proteins that may alter their conformation and unfold upon adhesion to a surface.…”

An approach to the research on ion and water properties in the interphase between the plasma membrane and bulk extracellular solution

“…Theoretically, this method can detect the profile of submonolayer structures of the molecules in the interface [ 22 ]. The properties of a water molecule were examined by SFG spectroscopy in the interface between the medium and the substrate coated by a polymer brush, highly condensed polymer chains like a forest [ 23 ] (Fig. 4 a).…”