Effects of Self-Healing Coating on Magnesium Alloys for Bone Implant

Objectives: Magnesium(Mg) alloys are considered as potential candidates in oral and maxillofacial fields, due to their biodegradability, biocompatibility and osteogenic property. However, the rapid degradation rate hinders its clinical application. Herein, we developed a self-healing coating to reduce the degradation rate of Mg alloys.
Methods: A spin coating method was used to prepare the coating on Mg alloy surface. Electrochemical tests and immersion tests were carried out to measure the degradation behavior of Mg alloys. The cytocompatibility of samples were evaluated by CCK-8 tests. The related expression of ALP, RUNX2 and OCN in human bone marrow mesenchymal stem cells (hBMMSCs) was detected by real-time quantitative PCR. Then, the coated and uncoated samples were implanted into rat femora. After 12 weeks, specimens were scanned by micro-computed tomography (Micro-CT). Hard tissue sections were stained with methylene-blue/acid fuchsin.
Results: The fabricated coating exhibited fast self-healing response and slow down the corrosion rate of Mg alloys. The coated group showed better biocompatibility and a higher level of gene expression compared with the untreated group. At 12 weeks, Micro-CT reconstruction results showed that the degradation of the coated group was uniform and mild, while the untreated group went through a large area of corrosion pits. Histological analysis of rat femora section demonstrate enhanced osseointegration for the coated group.
Conclusions: Self-healing coating is an effective mean to control the degradation rate and promote osteogenesis of Mg alloys. The deleloped coating show great potential for oral and maxillofacial application.