Biomolecule−Biomaterial Interaction: A DFT-D Study of Glycine Adsorption and Self-Assembly on Hydroxylated Cr₂O₃ Surfaces

Abstract

The adsorption of glycine, the building block of amino acids, on hydroxylated (0001)-Cr2O3 model surfaces, representing the stainless steel passive film surface, was modeled by means of the GGA + U method. The roles of glycine coverage and surface termination (hydroxylated Cr- and O-terminated surfaces) on the adsorption mode and self-assembly properties were explored. The hydroxylated Cr-terminated Cr2O3 surface, which presents two types of (H)OH groups exhibiting different acidic character, is more reactive than the hydroxylated O-terminated surface, where one single type of OH group is present, for all adsorption modes and coverages considered. Outer sphere adsorption occurs in the zwitterion form, stabilized at low coverage through H-bond formation with coadsorbed water molecules, and at the monolayer coverage by glycine self-assembling. The OH substitution by glycinate is favored on the hydroxylated Cr-terminated surface and not on the O-terminated one. The inclusion of dispersion forces does not change the observed tendencies. An atomistic thermodynamics approach suggests that outer sphere adsorption is thermodynamically favored over inner sphere adsorption in the whole domain of glycine concentration. The obtained SAM's free energies of formation are rationalized in a model considering the balance between sublimation and solvation free energies, and extrapolated to other amino acids, to predict the SAMs formation above hydroxylated surfaces. It is found that hydrophobic AA tend to self-assemble at the surface, whereas hydrophilic ones do not.

Understanding small biomolecule‐biomaterial interactions: A review of fundamental theoretical and experimental approaches for biomolecule interactions with inorganic surfaces

“…Small size biomolecule (single amino acid) interactions with oxidized surfaces can now be treated with ab initio techniques 76–91. The interactions of amino‐acids with dry surfaces were studied.…”

Surface-protein interactions on different stainless steel grades: effects of protein adsorption, surface changes and metal release

“…For stainless steels, both physisorption and irreversible chemisorption of proteins may be possible [12–14]. Surface complexation between serum proteins and the surface metal hydroxide has been suggested as the main reason for metal released from stainless steel (316) powder (55 μm) at both in vitro and in vivo conditions [15].…”

Density Functional Theory Study of Monoethanolamine Adsorption on Hydroxylated Cr2O3Surfaces

“…24 The structure of the surface will be described later. In brief, the Cr that are exposed to the aqueous phase have a saturated coordination (6), as in the bulk, resulting from the adsorption of 3 water molecules per Cr atom ( Figure 1).…”

“…This is in agreement with the known nonacidic character of this surface. 24 Indeed, the possibility of interaction through a NH 3 + group is expected on acidic surfaces such as the hydroxylated silica surface. 43 The fast deprotonation of MEAH + , which corresponds to an electrochemical reduction reaction, also suggests that this cation has the ability to act as oxidizer for the global corrosion reaction.…”