The Potential of Calcium/Phosphate Containing MAO Implanted in Bone Tissue Regeneration and Biological Characteristics

Abstract

Micro arc oxidation (MAO) is a prominent surface treatment to form bioceramic coating layers with beneficial physical, chemical, and biological properties on the metal substrates for biomaterial applications. In this study, MAO treatment has been performed to modify the surface characteristics of AZ31 Mg alloy to enhance the biocompatibility and corrosion resistance for implant applications by using an electrolytic mixture of Ca3(PO4)2 and C10H16N2O8 (EDTA) in the solutions. For this purpose, the calcium phosphate (Ca-P) containing thin film was successfully fabricated on the surface of the implant material. After in-vivo implantation into the rabbit bone for four weeks, the apparent growth of soft tissues and bone healing effects have been documented. The morphology, microstructure, chemical composition, and phase structures of the coating were identified by SEM, XPS, and XRD. The corrosion resistance of the coating was analyzed by polarization and salt spray test. The coatings consist of Ca-P compounds continuously have proliferation activity and show better corrosion resistance and lower roughness in comparison to mere MAO coated AZ31. The corrosion current density decreased to approximately 2.81 × 10−7 A/cm2 and roughness was reduced to 0.622 μm. Thus, based on the results, it was anticipated that the development of degradable materials and implants would be feasible using this method. This study aims to fabricate MAO coatings for orthopedic magnesium implants that can enhance bioactivity, biocompatibility, and prevent additional surgery and implant-related infections to be used in clinical applications.

In Vivo Degradation Behavior of Magnesium Alloy for Bone Implants with Improving Biological Activity, Mechanical Properties, and Corrosion Resistance

“…In other words, a thicker coating can be obtained with a calcium compound containing MAO. This is consistent with previous research, where more Ca 2+ and PO 4 –3 ions were added to the MAO treatment solution, which increased the coating thickness [ 40 ].…”

“…It showed lower corrosion rates for the MAOCa-coated samples than for the bare ZK60 and MAO-coated samples in the SBF solution. This is because Ca 2+ and PO 4 –3 ions can reduce the corrosion rate to protect biodegradable medical materials [ 40 , 44 , 45 , 46 ]. Figure 5 shows the thickness measurements for both MAO-coated ZK60 samples, recorded every 1 week during long-term immersion in test solutions.…”

“…Mechanical properties were measured using a biaxial servo-hydraulic machine (MTS Mini Bionix II 858). The bone screw was manufactured as a tensile specimen, followed by the design [ 40 ].…”

Microstructure, Mechanical Properties, In Vitro Biodegradability, and Biocompatibility of Mg-Zn/HA Composites for Biomedical Implant Applications

“…One practical approach is fabricating protective coatings with multi-functionalities on the magnesium substrate [ 7 ]. In recent years, several techniques for converting or depositing coatings onto Mg substrates have been explored, including chemical conversion [ 8 ], plasma electrolytic oxidation (PEO) [ 9 ], micro-arc oxidation [ 10 ], hydrothermal treatment [ 11 ], and immersion coating [ 12 ]. However, the functionality of surface coatings is limited to the early stages of immersion in physiological solutions, as only the exposed surfaces of implants can be coated, leaving the entire substrate untreated [ 13 ].…”