Plasma-assisted fabrication of antimicrobial coatings on titanium implants

Titanium (Ti) and its alloys are the most commonly used materials for the production of metallic medical implants due to their promising characteristics, including bioinertness, corrosion resistance, and biocompatibility. Nevertheless, these materials exhibit inadequate osseointegration capabilities, leading to implant failure. Additionally, Ti lacks inherent antibacterial properties, and bacterial-induced inflammation is another major contributor to implant loosening. To address these challenges, we successfully deposited zinc (Zn) doped TiO2 coatings onto commercially pure Ti (grade 2) using the unipolar pulsed plasma electrolytic oxidation (PEO) method under diverse experimental conditions i.e. Zn concentration in the range of 10 – 100 mM and treatment time of 3 and 5 min. Subsequently, the coatings were characterized microscopically, spectroscopically, and mechanically. Spectroscopic and microscopic analyses revealed that the deposition parameters have a significant influence on the coating morphology and degree of crystallinity. Scanning electron microscopy (SEM) illustrated that the increased Zn concentration likely promotes the formation of a more textured morphology and molten-like deposition with increased pore density and roughness, while increased coating time leads to larger and interconnected pores with microcracks at higher concentration. X-ray diffraction (XRD) spectra confirmed that elevating the Zn concentration and extending the treatment time yielded dense, and crystalline TiO2 coatings. Furthermore, mechanical analysis revealed a substantial enhancement in surface hardness (approximately 100% compared to the bare substrate) for the coatings deposited at a higher concentration (50 mM) and subjected to a longer treatment time (5 min). Consequently, plasma-assisted fabrication of doped bioactive coatings emerges as a promising approach for enhancing implant performance.