PEO coatings design for Mg-Ca alloy for cardiovascular stent and bone regeneration applications

Four bioactive PEO (plasma electrolytic oxidation) coatings were generated on Mg0.8Ca alloy using a Ca/P-based electrolyte and adding Si or Fas necessary. Surface characteristics, chemical composition and ion liberation of the coatings were characterized using SEM/EDS (Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy), X-ray diffraction, optical profilometry and ICP-OES (inductively coupled plasma optical emission spectrometry). Direct biocompatibility studies were performed by seeding premyoblastic, endothelial and preosteoblastic cell lines over the coatings. Biocompatibility of the coatings was also evaluated with respect to murine endothelial, preosteoblastic, preosteoclastic and premyoblastic cell cultures using extracts obtained by the immersion degradation of the PEO-coated specimens. The coatings reduced the degradation of magnesium alloy and released Mg Ca, P, Si and F. Of all the studied compositions, the Si-containing PEO coating exhibited the optimal characteristics for use in all potential applications, including bone regeneration and cardiovascular applications. Coatings with high F content negatively influenced the endothelial cells. RAW 264.7, MC3T3 and co-culture differentiation studies using extracts of PEO coated Mg0.8Ca demonstrated improved osteoclastogenesis and osteoblastogenesis processes compared to bare alloy.This work was funded by Regional Government of Madrid and EU Structural Funds (S2013/MIT-2862-CM, P2018/NMT-4411). A. Santos- Coquillat is grateful to Youth Employment Initiative (YEI) of Regional Government of Madrid and EU Social Funds for financial support (PEJD-2016/IND-3095). M. Mohedano gratefully acknowledges the support of MINECO (MAT20I5-733 55-JIN).Peer Reviewe