Corrosion resistance with self-healing behavior and biocompatibility of Ce incorporated niobium oxide coated 316L SS for orthopedic applications.

Ceramic oxide coatings are widely used in biomedical applications due to their ability to bond with bone and soft tissues. In the present study, we focus on improving the biocompatibility and corrosion resistance with self-healing properties of 316L SS by coating with cerium (Ce) incorporated niobium oxide (Nb 2 O 5) bioceramics synthesized by sol-gel technique. The effect of Ce concentrations in Nb 2 O 5 on the surface properties of 316L SS and its self-healing process during electrochemical corrosion in simulated body fluid (SBF) were deeply analyzed. The surface functional groups, morphology, chemical composition and phase transitions present in the coatings were analyzed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), high resolution scanning electron microscopy (HRSEM) with elemental dispersive X-ray (EDX) and X-ray diffraction (XRD) studies respectively. Chemical states of Ce and Nb in the Ce incorporated niobium oxide coating were identified by X-ray photoelectron spectroscopic (XPS) studies. Results show that Ce is present as both Ce3+ and Ce4+ oxidation states in CeO 2 form whereas Ce3+ is the main species and Nb is present as Nb5+ oxidation state exists in Nb 2 O 5 form. Ce incorporated Nb 2 O 5 coatings improved the surface roughness (R a) and hydrophilic nature of 316L SS, studied through atomic force microscopy (AFM) and water contact angle measurements. Electrochemical studies were performed for the specimens immediate and after 7 days immersions in SBF solution to evaluate the corrosion resistance with self-healing behavior. Results show that increased corrosion resistance with reduction in current density (i corr) and corrosion potential (E corr) and breakdown potential (E break) shifts towards more positive potentials from potentiodynamic polarization studies whereas increased impedance values and good capacitance behavior in the low frequency regions were measured from electrochemical impedance spectroscopic (EIS) studies for the Ce incorporated Nb 2 O 5 coated 316L SS specimens. Cell culture studies were performed on specimens using osteoblast MG 63 cells, among those Ce incorporated Nb 2 O 5 coatings were showed enhanced biocompatibility for 316L SS with improved cell adhesion, significant cell spreading, proliferation and differentiation of cells. Schematic representation of the self-healing behavior of Ce incorporated Nb 2 O 5. Unlabelled Image • Successful fabrication of functional Ce incorporated Nb 2 O 5 coating over 316L SS to best fit for implant applications. • Surface morphology and properties of 316L SS were greatly enhanced by Ce incorporated Nb 2 O 5 coatings. • Enhanced corrosion resistance with self-healing behavior by Ce incorporated Nb 2 O 5 coating over 316L SS. • The Ce incorporated Nb 2 O 5 coated 316L SS exhibited more biological activity in promoting MG 63 osteoblast cells. [ABSTRACT FROM AUTHOR]