A biodegradable, mechanically tunable micro‐arc oxidation AZ91D‐based composite implant with calcium phosphate/chitosan coating promotes long‐term bone tissue regeneration

Abstract

Background To reduce the biodegradable rate and develop the long‐term osteogenic ability of magnesium (Mg) alloy, we prepared a new biodegradable micro arc oxidation AZ91D‐based composite implant with calcium phosphate/chitosan coating (CaP‐CS/MAO/AZ91D) and investigated its mechanical property and long‐term bone tissue regeneration ability. Main Methods and Major Results The results showed that the binding force and bioactivity of CaP‐CS/MAO/AZ91D was better when the ratio of water to ethanol was 4:6 and MAO constant current was 0.1 A cm−2. Compressive strengths of 4:6 sample were more than 1300 N when the soaking time was increased to 21 days. CaP‐CS/MAO/AZ91D extracts promoted differentiation and proliferation of rat mesenchymal stem cells (RMSC), which achieved higher proliferation rates over 16 days of culture and exhibited early alkaline phosphatase activity and late bone sialoprotein markers. Conclusions and Implications CaP‐CS/MAO/AZ91D was established to promote RMSC osteogenic differentiation within a proper range for at least 90 days through Wnt/β‐catenin pathway activation, which would allow sufficient time for bone healing. Collectively, our findings suggest that the CaP‐CS/MAO/AZ91D coating could not only reduce the corrosion rate and lead to better long‐term biocompatibility but also promote osteogenic mineralization.

Composite Nanocoatings of Biomedical Magnesium Alloy Implants: Advantages, Mechanisms, and Design Strategies

“…In addition to promoting osteogenesis by accelerating apatite formation and deposition, [36,104] nanomaterials may upregulate osteogenic signaling pathways to promote cell proliferation, differentiation, and secretion of mineralized matrix. [36,83,[124][125][126] Composite nanocoatings of Mg alloy surfaces may act on BMP/SMAD, [127] Wnt/𝛽-Catenin, [128] ERK/MAPK, [124,129] and other signaling pathways related to osteogenic differentiation. [130] These pathways regulate the key transcription factor Runx2 and the expression of major downstream osteogenic differentiation factors and genes (such as osterix, ALP, OCN, COL-1, and OPN) to facilitate bone regeneration (Figure 4).…”

The effects of electrodeposition temperature on morphology and corrosion resistance of calcium phosphorus coatings on magnesium alloy: comparative experimental and molecular dynamics simulation studies

“…11 Several techniques have been reported to deposit CaP coatings on magnesium alloys, including sol-gel process, chemical conversion methods, micro arc oxidation process, hydrothermal and electrodeposition. [12][13][14][15][16] Electrodeposition is widely used for prepare Mg-based coatings because the process involves simple, controllable and able to obtain uniform coating on the complex shape matrix. Moreover, the coating thickness, morphology, structure and component can be optimized by varying the plating parameters, temperature, pH and electrolyte composition.…”