Impressive strides in antibacterial performance amelioration of Ti-based implants via Plasma Electrolytic Oxidation (PEO): A review of the recent advancements

• The effect of critical implant pretreatment parameters are reviewed. • Nanoparticle addition and duplex treatment dominate antibacterial PEO coatings. • Bacteria-killing methods like contact, release, trap and photocatalysis are discussed. • Photocatalytic and release killing of PEO coatings investigation is extremely needed. Ti and Ti-alloys are widely utilized as suitable biomaterials for implants, since they present good biocompatibility and mechanical properties. However, they can be an ideal substrate for bacteria attachment, promoting biofilm infections. Biomaterial-associated infections is one of the major healthcare challenges that is currently faced by humanity. This fact causes increased morbidity and distress in patients, along with high economic costs due to increased hospitalizations. There are several strategies to overcome the biofilm infection associated to implants, especially plasma electrolytic oxidation (PEO) process. PEO is highly effective in the production of hard, porous, wear- and corrosion-resistant, as well as biocompatible coatings. Additionally, this method can be applied to introduce antibacterial coatings, with the most prevalent ones being bacteria-killing and bacteria-repelling. Thus, in this review, the biofilm formation implications in implants are presented, as well as the antibacterial mechanisms presently known. The effect of PEO on the antibacterial ability of Ti and Ti-alloys will then be discussed in detail. Finally, the PEO procedure parameters and modifications that lead to high performance of antibacterial implants will be presented.