Review of Antibacterial Activity of Titanium-based Implants Surfaces Fabricated by Micro-arc Oxidation

Abstract

Ti and its alloys are the most commonly used materials for biomedical applications. However, bacterial infection after implant placement is still one of the significant rising complications. Therefore, the application of the antimicrobial agents into implant surfaces to prevent implant-associated infection has attracted lots of attentions. Scientific papers have shown that inorganic antibacterial metal elements (e.g. Ag, Cu, Zn) can be introduced into implant surfaces with the addition of metal nanoparticles or metallic compounds into electrolyte via micro-arc oxidation (MAO) technology. In this review, the effects of the composition and concentration of electrolyte and process parameters (e.g. voltage, current density, oxidation time) on morphological characteristics (e.g. surface morphology, bonding strength), antibacterial ability and biocompatibility of MAO antimicrobial coatings were discussed in detail. Anti-infection and osseointegration can be simultaneously accomplished with the selection of the proper antibacterial elements and operating parameters. Besides, MAO assisted by magnetron sputtering (MS) to endow Ti-based implant materials with superior antibacterial ability and biocompatibility was also discussed. Finally, the development trend of MAO technology in the future was forecasted.

Use of Plasma Technologies for Antibacterial Surface Properties of Metals

“…Magnets are introduced beneath the target material to increase deposition rates, resulting in secondary electrons being bound to the near-surface region of the target. These secondary electrons further improve the intensity of ion bombardment and, therefore, also help to improve the deposition rate of coatings onto the substrate [ 90 ].…”

“…The combination of the substrate (cathode), vessel (anode), electrolyte, distance, temperature, and other parameters play a crucial role in the composition of the produced thin coating and its morphology. Technologically relevant passive films are made by combining electrode metal and electrolyte to exhibit ion conductivity while exhibiting no electron conductivity [ 90 , 92 , 93 ].…”

“…However, it is necessary to precisely control the concentration and content of the antibacterial metal elements, electrolytes as well as PEO parameters to optimize antibacterial properties and at the same time prevent cytotoxicity. It is also possible to enhance both the antibacterial properties as well as bioactivity by the simultaneous addition of antibacterial metal elements and bioactive elements, such as strontium (Sr) and silicon (Si) in the PEO electrolyte [ 90 ]. For instance, Santos-Coquillat et al [ 115 ] treated Ti 6 Al 4 V alloy with PEO using an F-containing electrolyte.…”

Surface modification of valve metals using plasma electrolytic oxidation for antibacterial applications: A review

“…At this threshold potential microdischarging occurs due to the ionization of gas bubbles, resulting in local thickening of oxide layer . When the newly evolved oxide layer can cause enough resistance in current flow the other parts with lower resistance tend to breakdown, in this way oxidation of whole surface takes place . During the early stage of oxidation, growth direction is predominantly outward, while in later stage growth is preferably inward .…”

“…Several metallic nanoparticles have been employed in literature to develop antibacterial coatings. Although these metals exhibit attractive antibacterial characteristics but their cytotoxicity, long‐term in vivo behavior and harmful environmental effects are important concerns. AgNPs and CuNPs have been employed most abundantly as antibacterial agents.…”