Effects of hydroxyapatite coatings on enhanced corrosion protection and cytocompatibility of high-purity magnesium

Magnesium (Mg) and its alloys are promising materials for temporary biomedical implants such as bone fracture fixation devices. Unfortunately, rapid degradation in the physiological environment and cytotoxicity have impeded their clinical use. Hydroxyapatite (HA) coatings synthesized via ethylenediaminetetraacetic acid calcium disodium salt hydrate (EDTA-Ca) and potassium dihydrogen phosphate (KH2PO4) have emerged as one effective strategy to enhance the corrosion resistance and biocompatibility of Mg and its alloys. However, effects of the concentrations of EDTA-Ca and KH2PO4 on the morphology, corrosion protection, and biocompatibility of HA coatings remain unclear. In this study, the morphology, thickness, corrosion protection, and cytocompatibility of the HA coatings fabricated on high-purity Mg with different concentrations of the synthetic solution are investigated. Our results show that the fabricated coatings are composed of a dome-shaped outer HA layer and an inner Mg(OH)(2) layer. With decreasing the concentrations of the synthetic solution, the HA and Mg(OH)(2) layers become thinner and thicker, respectively, and the corrosion resistance and cytocompatibility of the coated Mg become better. The formation mechanism of the prepared coatings and relationships between the concentrations of the synthetic solution and the corrosion and biological characteristics are also discussed.

Automated summary

Magnesium and its alloys have potential as temporary biomedical implants, but their rapid degradation and cytotoxicity hinder clinical use. Hydroxyapatite coatings can enhance corrosion resistance and biocompatibility. This study investigates the effects of synthetic solution concentrations on coating morphology, corrosion protection, and cytocompatibility.