Identification and binding mechanism of phage displayed peptides with specific affinity to acidalkali treated titanium

Abstract Acid⿿alkali treatment is one of means widely used for preparing bioactive titanium surfaces. Peptides with specific affinity to titanium surface modified by acid⿿alkali two⿿steps treatment were obtained via phage display technology. Out of the eight new unique peptides, titanium⿿binding peptide 54 displayed by monoclonal M13 phage at its pIII coat protein (TBP54⿿M13 phage) was proved to have higher binding affinity to the substrate. The binding interaction occurred at the domain from phenylalanine at position 1 to arginine at position 6 in the sequences of TBP54 (FAETHRGFHFSF) mainly via the reaction of these residues with the Ti surface. Together the coordination and electrostatic interactions controlled the specific binding of the phage to the substrate. The binding affinity was dependent on the surface basic hydroxyl group content. In addition, the phage showed a different interaction way with the Ti surface without acid⿿alkali treatment along with an impaired affinity. This study could provide more understanding of the interaction mechanism between the selected peptide and its specific substrate, and develop a promising method for the biofunctionalization of titanium.