Implantable biomaterials such as those used for bone replacement and tissue fixation in both dentistry and orthopedics are ought to have optimal physicochemical properties such as strength and toughness depending on the application site [1], [2], [3]. Titanium (Ti) is widely used as an implant material in these areas not only because of its metal-specific strength and toughness, but also because of its unique chemical properties including corrosion resistance and biocompatibility [4], [5].

On the other hand, implant materials utilized for hard tissue reconstruction often suffer from infections, resulting in loosening and poor fixation of the implant [6]. Therefore, research on antibacterial implant materials recently gained substantial scientific interest [7], [8]. For example, the graphene oxide coating is applied to avoid bacterial infections [9], [10]. Also, antibacterial metallic components such as silver, nickel, copper, and cobalt [11], [12], [13] are introduced in the implant materials for exhibiting antibacterial properties. Since the modification and application of these materials are complicated, additional simplified approach to obtain anti-bacterial surface is demanded.

Our previous study demonstrated that acid-treated Ti has higher adhesiveness to biological soft tissue [14]. The surface area of this acid-treated Ti increases as the surface roughness increases. By reducing the hydration layer on the surface of the acid-treated Ti, especially towards the intermediate water, this acid-treated Ti shows higher adhesion to organic molecules including collagens and polysaccharides [15]. Bacteria are also covered with an organic matrix containing polysaccharides and proteins. Here, we hypothesized that the physiochemical characteristics of acid-treated Ti have potential for trapping bacteria and hence promoting anti-bacteria properties. Therefore, the purpose of this study was to investigate the potential of the surface physicochemical properties of acid-treated Ti on the trapping and killing of bacteria.