Rational design of additively manufactured Ti6Al4V implants to control Staphylococcus aureus biofilm formation

Bacterial attachment and subsequent biofilm formation on medical implants presents a serious infection risk. The precision, personalisation and superior functionality of additive manufacturing techniques, such as selective laser melting (SLM), enables the fabrication of metallic implants with patient specific customisation. An unexpected outcome of this process, however is a hitherto unachievable fine control over the bio-interface in a single manufacturing step. Here, for the first time, we report on how the SLM build inclination angle can be utilised to modify the surface topography of metallic implants for directed Staphylococcus aureus biofilm restriction. From an initial build inclination angle of 90°, lowering the angle gave metallic surfaces with lower roughness, lower hydrophobicity, higher surface energy, and fewer partially melted metal particles without altering the bulk surface chemistry. This directly correlated with significantly lower biofilm coverage and an associated reduction in biomass without compromising mammalian cell viability and attachment. This work provides a facile single step method at the manufacturing stage for the development of additively manufactured metallic implants with superior, inherent protection against implant associated infection.