Biopanning and Design of RGD-Modified Phage Displayed Titanium-Binding Peptides With Biofunctionality and Binding Stability

The development of multifunctional surfaces for titanium implants has become a hot research area due to their potential to elicit specific responses from various cells and infection agents. Solid-binding peptides are increasingly exhibiting their distinct advantages as a novel noncovalent surface modification method for titanium implants. In this study, titanium-binding peptide (TiBP2), a titanium-binding peptide with higher affinity for acid–alkali treatment titanium (AA) substrate, was screened using the phage display technique. The excellent affinity and stable binding of TiBP2 to the AA substrate was due to the interaction of its COO^– group with Ti⁴⁺ on the AA substrate. Linker-conjugated RGD–TiBP (TPR/TGR) was constructed, and its binding capacity and biofunctionality were analysed. RGD-TiBP exhibited high affinity and stable binding properties with AA substrate, as well as excellent biocompatibility (no toxic effect on L929 cells) and remarkable H₂O₂ scavenging ability. Notably, 40 μg/mL of TPR effectively promoted the polarisation shift of macrophages from a pro-inflammatory phenotype (M1) to an anti-inflammatory phenotype (M2). The present results indicated that TPR-based biofunctional modification of titanium implants can improve interfacial stability and immunomodulatory activity, making it a promising technique for application.