BIFUNCTIONAL DESIGNED PEPTIDES INDUCE MINERALIZATION AND BINDING TO TIO₂

The demand for orthopedic medical implants in humans is increasing rapidly each year. One of the major limitations in titanium implants is the rather poor bonding between the implant interface and the surrounding tissue which may lead to implant failure.

In this research we aimed at developing functional peptides to form monomolecular coatings intended to improve adhesion between the native oxide of the metal (TiO₂) and the bone with which it is in contact. Accordingly, a bifunctional peptide with a β-strand motif assumed to strongly bind to the oxide though two phosphorylated serine residues, both situated on the same face of the strand, was designed. The β-strand motif was extended by a mineralization ‘tail’ composed of consecutive acidic amino acids capable of adsorbing calcium ions. This peptide was studied together with two additional control peptides, one serving to elucidate the role of the β-strand in stabilizing bonding with the oxide, and the other demonstrating the ability of the tail to induce mineralization. The strong adsorption of the three peptides to the oxide surface was revealed by HPLC. That peptide presenting the mineralization tail showed the highest levels of adsorbed calcium and phosphate ions, as well as the largest area of cellular adherence, demonstrating its potential advantages for use with titanium implants in bone tissue.