Abstract

Titanium alloys are the material of choice for many biomedical devices due to their excellent mechanical, physical, and biological performance. However, such surfaces are targets for surgical infections unless treated with antimicrobial agents like antibiotics, peptides, and/or metallic nanoparticles. In this work, a cathecol-based mussel-derived adhesive sequence was synthesized in peptidic constructs with a silver nanoparticle (AgNPs)-binding sequence, resulting in bifunctional peptides able to preserve both activities. The quartz crystal microbalance analysis allowed us to select the best construct for obtaining a stable two-step coating, in which the bifunctional peptide was added onto the titanium surface, followed by the adhesion of AgNPs to the peptide. Contact angle measurements showed that the presence of the peptide on the surface enhanced wettability, whereas the subsequent adhesion of AgNPs increased the contact angle to values slightly higher than 90°, resulting in a hydrophobic surface and indicating the formation of a two-step coating process. On the other hand, the presence of the AgNPs on the surface was corroborated by X-ray photoelectron spectroscopy, which showed characteristic silver signals, and by scanning electron microscopy, which indicated a density of 76 × 1012 particles/cm2 on the surface, with a prevalence of spherical nanoparticles with an average size of 51 ± 13 nm. Atomic force microscopy measurements corroborated these results, showing increased roughness due to silver nanoparticle adsorption. Finally, we were able to infer the presence of the NPs on the surface and the preferred orientation of the peptide 6Y system on the Ti surface using Raman spectroscopy. The antibacterial activity of the coating was measured using the ISO 22196:2011 standard for plastic and other non-porous surfaces, demonstrating that silver-nanoparticle-coated titanium surfaces exhibit antimicrobial properties against E.coli and S.aureus, killing 100 % of the bacteria after 3 and 24 hours of exposure, respectively, in comparison to the uncoated surface, with no cytotoxicity on fibroblasts. This is the first report on the immobilization of silver nanoparticles on titanium surfaces using synthetic peptides, and it could be applied to other surfaces where the catechol group has demonstrated effective adhesion for a variety of applications, including electronics, water treatment, and biomedicine. © 2025 Elsevier B.V.