An in situ Infrared Spectroscopic Study of Glutamic Acid and of Aspartic Acid Adsorbed on TiO2: Implications for the Biocompatibility of Titanium

Aqueous Peptide–TiO2 Interfaces: Isoenergetic Binding via Either Entropically or Enthalpically Driven Mechanisms

“…The larger, softer layer formed in H2O would be prone to disruptions during washing while a smaller rigid film may not be as exposed during washing. In H2O buffer conditions, for both Ti-1 and Ti-2, dissipation energy data, Figure 2b, indicated that a secondary layer was formed during adsorption, and desorption of the peptide in the case of Ti-1 may be driven, at least in part by the presence of a large number of hydrophobic amino acid residues, which is in agreement to what was observed by McQuillan et al 18 and as was found for a purely hydrophobic peptide AFILPTG from a silica surface. 51 In summary, peptides Ti-1 and Ti-2 show different adsorption/desorption behavior in water (pH 7.4) and salt (0.15M) which can in part be ascribed to differences in their chemical properties, including the numbers of charged and hydrophobic residues.…”

“…Overall, the broad view from these experimental and simulation studies indicate that charged (R, K, D, E) and to a lesser extent polar (S, T, N, Q, Y) amino acids show the greatest degree of titania adsorption, while hydrophobic residues (V, L, I, F) exhibit negligible to zero binding affinity; simulations 19,23 suggest that these residues actually have a repulsive interaction with aqueous titania. In particular, the fact that negatively-charged amino acids, such as aspartate and glutamate, can adsorb appreciably to a negatively-charged aqueous titania interface is counter-intuitive at first glance, but has been confirmed by previous experimental studies (see for example McQuillan and co-workers 18 ), and was supported by subsequent molecular dynamics simulations that quantified the free energy of adsorption and the associated binding structures at the interface. 19 These simulation data suggested that this phenomenon could be ascribed to the nanoscale patterning of partial positive charge and negative charge, inherent to the presentation of both Ti and H, and O atoms at the surface.…”

“…Several experimental and computational studies have focused on the fundamentals of recognition between titania and amino acids, [18][19][20][21][22][23][24][25] for which much (but not all -see the work of e.g. McQuillan and co-workers 18 ) of the experimental work has been done in vacuo, which is most probably not directly relevant to aqueous conditions.…”

The effect of humic acid on the aggregation of titanium dioxide nanoparticles under different pH and ionic strengths

“…It can be associated with TiO 2 NPs through electrostatic attraction. Theoretical and experimental studies on the adsorption of various organic compounds onto TiO 2 indicate that the carboxyl and phenolic functional groups in NOM can bind to Ti or O atoms on the TiO 2 surface (Langel and Menken, 2003;Persson and Lunell, 2000;Roddick-Lanzilotta and McQuillan, 2000).…”

Surface Properties of a Nano-Quasicrystalline Forming Ti Based System

“…23) Since quasicrystal surface energy is rather low 3,24) due to their peculiar electronic structure at Fermi level, 25) their surface reactivity with respect to biomolecules may be different from those measured on ''classical'' metallic systems. [26][27][28] Adsorption of L-glutamic acid, an amino acid involved in protein adsorption, 28) has been investigated on the surface of Ti 45 Zr 38 Ni 17 ribbons by Polarisation Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS), using pure titanium and pure zirconium as references.…”