Titanium and platinum samples as components of bimetallic implants for the osteoregeneration process have been modified in solutions modeling biological systems and studied by means of cyclic ...voltammetry, electrochemical impedance spectroscopy and scanning probe microscopy. While aspartic and glutamic acids did not adsorb significantly on platinum in the potential region investigated, the presence of the amino acids affects oxide layer growth on the titanium surface under anodic polarization. The two studied amino acids behave differently on the titanium electrode surface due to differences in adsorption modes of these substances. The adsorption of the glutamic acid depends on the polarization potential to a large extent, and most of quantitative adsorption characteristics (EIS data, the surface roughness) undergo drastic change at the polarization potential value of 750 mV (vs. Ag/AgCl) in the presence of this substance. Equivalent circuit modeling of the surface processes has been carried out, and a scheme for aspartic and glutamic acid adsorption onto the titanium surface has proposed.
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•Glutamic acid adsorption is determined by potential applied to the titanium electrode.•Aspartic acid adsorbs on a titanium electrode surface through both carboxylic groups.•Titanium surface characteristics depend on both potential and amino acid presence.•Dicarboxylic amino acids interact strongly with a titanium electrode surface.•Aspartic and glutamic amino acids adsorption on platinum electrode is negligible.
An attempt was made to simulate the electrochemical behavior of the osteocalcin active site simple models on the platinum component of a bimetallic Ti/Pt implant. Dicarboxylic glutamic acid and ...dicarboxylic aspartic acid, and ethylmalonic acid as the third model successfully complementing the model range. The surface coverage of the platinum electrode during adsorption of model dicarboxylic acids was estimated using cyclic voltammetry and electrochemical impedance spectroscopy. All three compounds demonstrate similar trends in the surface coverage dependencies on the adsorption potential, acids' adsorption onto platinum surface is weak, and in none of cases studied amino group participates in adsorption on the platinum electrode surface. Using quantum chemical calculations, the most stable conformations of model compounds and the values of voids between adsorbed dicarboxylic acid molecules were obtained. Since all three models have a relatively low surface coverage and are participants in the outer sphere process of nonspecific adsorption on platinum, the residues of γ-carboxyglutamic acid present in osteocalcin will not be specifically adsorbed on the platinum component of the bimetallic implant, and the absence of interactions between it and the platinum electrode should have a positive effect on the dynamics of osteoregeneration.
