Plasma-assisted fabrication of biocompatible 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 calcium phosphate-based coatings onto commercially pure Ti (grade 2) using the unipolar pulsed plasma electrolytic oxidation (PEO) method under diverse experimental conditions i.e. frequency in the range of 20 – 200 Hz and electrolyte pretreatment time ranging from 0 – 6 minutes. 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 coatings deposited at higher frequencies exhibited the characteristic PEO microstructure, while coatings deposited at lower frequencies manifested more pronounced electrochemical traits. X-ray diffraction (XRD) spectra confirmed that elevating the frequency and extending the electrolyte pre-treatment time yielded dense, phase-pure, and crystalline hydroxyapatite coatings. Furthermore, mechanical analysis revealed a substantial enhancement in surface hardness (approximately 31%) for the coatings deposited at a higher frequency (200 Hz) and subjected to a longer electrolyte pretreatment time (6 minutes). Consequently, plasma-assisted fabrication of bioactive coatings emerges as a promising approach for enhancing implant performance.