Interactions between oligopeptides and oxidised titanium surfaces detected by vibrational spectroscopy.

The interest in functionalised biomimetic materials used in prosthetic applications as bone substitutes has led to studies on regular alternating polar/non-polar oligopeptides such as EAK-16 (AEAEAKAKAEAEAKAK), first synthesised by Zhang et al. [1]. These peptides have a preferential beta-sheet structure, are resistant to proteolitic cleavage and able to self-assemble into an insoluble macroscopic membrane under physiologial conditions. Their ability to create such stable structures derive from the hydrophobic interaction between the aliphatic groups of non-ionic residues and complementary ionic bonds between acidic and basic amino acids: this stability can be enhanced by the regulation of pH and the presence of monovalent ions. In this context, we studied eight different oligopeptides derived from EAK-16, but modified in their sequence by amino acid substitution or by adding at the N-terminus of the sequence the RGD motif, present in the integrins located in the bone extracellular matrix and able to control osteoblast adhesion.