Functionalized titanium surfaces with anti-bacterial adhesion properties

Pure titanium and titanium alloys are the most used in dentistry and orthopedics because of their unique mechanical properties, corrosion resistance in biological media, and their good biocompatibility and osseointegration ability [1]. However, despite the outstanding mechanical and biological properties of titanium-based devices, the implant failure, mainly due to postoperative infection and/or immune responses, still remains a significant concern, leading to adverse clinical outcomes [2]. Among the different antibacterial compounds, quaternary ammonium salts (QASs) exert a strong antimicrobial activity against a wide class of microorganisms including bacteria, fungi, and viruses [3]. In this study, we investigated the possibility to develop inherent anti-bacterial medical devices by covalently inserting bioactive ammonium salts onto the surface of titanium metal substrates. Titanium discs have been modified by silane chemistry and functionalized with quaternary ammonium salts (QASs) and with oleic acid (OA). The samples have been characterized by ATR FTIR and SEM-EDX analyses and investigated for the roughness and hydrophilic behaviour. The bacterial adhesion inhibition tests performed against the Gram-negative Escherichia Coli and Gram positive Staphylococcus aureus, showed a clear anti-adhesion activity for the samples containing a long alkyl chain between the silicon atom and the ammonium functionality. The results of biological preliminary tests highlight the importance of chemical functionalization in addressing the antimicrobial activity of metal surfaces and open new perspectives in the development of antimicrobial implantable titanium medical devices.