Interaction of biologically relevant ions and organic molecules with titanium oxide (rutile) surfaces: A review on molecular dynamics studies

The surface of a biomaterial can play a major role in its biological fate since the surface is the primary pathway for its interaction with the body. As the natural response of the body to a foreign material is to encapsulate it with a fibrous material, the interactions between the body and the biomaterial are mediated by this fibrous layer. Initial interactions occur between the biomaterial surface, water, ionic species and organic molecules, which then mediate further interactions with body tissues. Surface engineering can influence these interactions and hence, improve the biocompatibility of the biomaterial. Therefore, both experimental and computational studies have been interested in phenomena happening at the solid-solution interface as their mechanisms and driving forces can point to new directions for biomaterial design and evaluation. In this review, we summarize the computational work on the interaction of titanium oxide surfaces (mainly rutile) with solvated ions and organic molecules by means of molecular dynamics, with a certain relevance to bioactivity testing protocols. The primary goal of this review is to present the current state of the art and draw attention to points where further investigations are required.