Laser-Assisted Nanotexturing and Silver Immobilization on TitaniumImplant Surfaces to Enhance Bone Cell Mineralization andAntimicrobial Properties

Despite the great advancement and wide use oftitanium (Ti) and Ti-based alloys in different orthopedic implants,device-related infections remain the major complication in modernorthopedic and trauma surgery. Most of these infections are oftencaused by both poor antibacterial and osteoinductive properties of theimplant surface. Here, we have demonstrated a facile two-step lasernanotexturing and immobilization of silver onto the titanium implantsto improve both cellular integration and antibacterial properties of Tisurfaces. The required threshold laser processing power for effectivenanotexturing and osseointegration was systematically determined bythe level of osteoblast cells mineralized on the laser nanotextured Ti(LN-Ti) surfaces using a neodymium-doped yttrium aluminumgarnet laser (Nd:YAG, wavelength of 1.06 mu m). Laser processing powers above 24 W resulted in the formation of hierarchicalnanoporous structures (average pore 190 nm) on the Ti surface with a 2.5-fold increase in osseointegration as compared to thepristine Ti surface. Immobilization of silver nanoparticles onto the LN-Ti surface was conducted by dip coating in an aqueous silverionic solution and subsequently converted to silver nanoparticles (AgNPs) by using a low power laser-assisted photocatalyticreduction process. Structural and surface morphology analysis via XRD and SEM revealed a uniform distribution of Ag and theformation of an AgTi-alloy interface on the Ti surface. The antibacterial efficacy of the LN-Ti with laser immobilized silver (LN-Ti/LI-Ag) was tested against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The LN-Ti/LI-Ag surface was observed to have efficient and stable antimicrobial properties for over 6 days. In addition, it was found thatthe LN-Ti/LI-Ag maintained a cytocompatibility and bone cell mineralization property similar to the LN-Ti surface. Thedifferential toxicity of the LN-Ti/LI-Ag between bacterial and cellular species qualifies this approach as a promising candidate fornovel rapid surface modification of biomedical metal implants.