Study on the effect and mechanism of gold nanocoated magnesium bone scaffolds for bone repair

In orthopedic patients, bone defects are often the result of infections, tumors, or trauma. Currently, bone grafting is the predominant method utilized to address these defects. Magnesium (Mg) and its alloys are commonly used in orthopedic grafting; however, their tendency to degrade rapidly poses a significant concern that must be addressed during their application. By employing microarc oxidation (MAO) technology to modify the coatings on magnesium metal surfaces, it is possible to improve the corrosion resistance of magnesium-containing implants. Nonetheless, this technique may undermine their antibacterial properties. Gold nanorods (AuNRs) exhibit exceptional antibacterial characteristics and the ability to facilitate bone regeneration. This study aims to explore the role and mechanism of a magnesium bone scaffold enhanced with gold nanoparticles in the context of bone repair.

The objective of this research was to explore the function and mechanism of a magnesium-based bone scaffold that had been enhanced with gold nanoparticles in the process of bone regeneration.

The gold nanoparticles were fixed on pure magnesium scaffolds after microarc oxidation through immersion coating and UV curing, following the screening of the appropriate concentration of AuNRs through cytotoxicity experiments. The microscopic morphology and pore structure characteristics of the magnesium bone scaffold's surface were examined using a scanning electron microscope (SEM). The gold nanocoated magnesium bone scaffold was immersed in phosphate buffer saline at a surface area/solution volume ratio of 1.25cm²/mL and subsequently placed in a 37 ℃ constant temperature incubator. The magnesium colorimetric method was employed to quantify the alterations in ion content in the supernatant on days 3, 5, 10, and 15. Simultaneously, the scaffolds were removed and weighed in weeks 1, 2, 3, and 4 to assess their biodegradability and weight loss. The antibacterial properties of the various categories of materials were assessed by counting the number of bacterial colonies on the plates, which were coated with bacterial solutions co-cultured with various materials from Staphylococcus aureus. The scaffold's in vitro activity in promoting bone and vascular migration was validated using MC3T3-E1 cells and vascular endothelial cells. The rabbit distal femoral defect model was used to assess the degradability and bone activity promotion of the porous scaffolds and porous particles in vivo. A cylindrical defect measuring Ø 2 × 5 mm was created at the femoral condyle of 24 Sprague-Dawley rats. Stent particles were inserted, and the rats were euthanized at 12 and 16 weeks to obtain femoral specimens. The samples were subsequently subjected to a variety of experiments, such as histological section analysis.

At a concentration of 15 µg/mL AuNRs, the biological properties and cell activity were satisfactory, suitable for coating preparation. The SEM results indicated that the AuNRs composite coating was effectively applied to the magnesium bone material's surface. The coating's ability to postpone the degradation of magnesium ions was demonstrated in in vitro magnesium ion release experiments. The MAO magnesium bone scaffold, which was modified with the AuNRs coating, exhibited a substantial antibacterial effect at 6 h and was capable of reducing the occurrence of preclinical infections, as indicated by the results of bacterial experiments. The MAO magnesium bone scaffold modified with the AuNRs coating exhibited favorable biological activity and osteogenic differentiation capacity, as indicated by the results of the cell culture experiments. Furthermore, animal experiments have demonstrated that the MAO magnesium bone scaffold, which has been modified with the AuNRs coating, can substantially enhance bone repair and enhance bone integration between the implant and the bone.

The biodegradation behavior in vitro and the osteogenic performance in vivo of magnesium bone scaffolds were thoroughly assessed using a variety of methods, with the corrosion resistance of these scaffolds being improved by the application of gold-infused nanocoatings on their surfaces. This research also facilitated osseointegration and enhanced the osteogenic potential of internal implants, aiding in the regeneration of bone loss areas. This study presents an innovative approach to the internal implantation treatment of patients suffering from bone defects.