Wenjing Yang

Fe has immense potential for biodegradable orthopedic applications, but it degrades slowly in the physiological environment. Inducing galvanic couple by alloying Cu to Fe using ball milling is a promising approach. However, the ductile nature of Cu leads to the cold welding of a large amount of Cu powder during ball milling, which makes it difficult to disperse uniformly in the Fe matrix. Here, a Fe-CuO implant with highly dispersed Cu particles in the matrix was developed by shift-speed ball milling and selective laser melting. Specifically, copper oxide (CuO) particles were selected as precursors and dispersed in Fe powders by ball milling since they were brittle and would not be cold-welded during ball milling. After further milling in higher energy, it was found that CuO particles reacted with Fe and generated Cu particles through a stress-activated redox reaction. Subsequently, the obtained powders were prepared into a Fe-CuO implant using selective laser melting. Microstructure examination revealed that the Cu phases in the implant were dispersed evenly in the Fe matrix, which was considered to establish a large number of galvanic couples and aggravated the galvanic corrosion tendency. Electrochemical tests indicated that the implant had improved performance in degradation behavior in terms of high corrosion current density (22.4 μA/cm²), low corrosion resistance (1319 Ω cm²), and good degradation stability. In addition, it presented antibacterial effects against Escherichia coli and Staphylococcus aureus by diffusion mechanisms with killing rates of 90.7 and 96.7%, respectively, as well as good cytocompatibility.

Background: Fe ₃ O ₄ nanoparticles are highly desired for constructing endogenous magnetic microenvironment in scaffold to accelerate bone regeneration due to their superior magnetism. However, their random arrangement easily leads to mutual consumption of magnetic poles, thereby weakening the magnetic stimulation effect. Methods: In this study, magnetic nanochains are synthesized by magnetic-field-guided interface co-assembly of Fe ₃ O ₄ nanoparticles. In detail, multiple Fe ₃ O ₄ nanoparticles are aligned along the direction of magnetic force lines and are connected in series to form nanochain structures under an external magnetic field. Subsequently, the nanochain structures are covered and fixed by depositing a thin layer of silica (SiO ₂ ), and consequently forming linear magnetic nanochains (Fe ₃ O ₄ @SiO ₂ ). The Fe ₃ O ₄ @SiO ₂ nanochains are then incorporated into poly l-lactic acid (PLLA) scaffold prepared by selective laser sintering technology. Results: The results show that the Fe ₃ O ₄ @SiO ₂ nanochains with unique core–shell structure are successfully constructed. Meanwhile, the orderly assembly of nanoparticles in the Fe ₃ O ₄ @SiO ₂ nanochains enable to form magnetic energy coupling and obtain a highly magnetic micro-field. The in vitro tests indicate that the PLLA/Fe ₃ O ₄ @SiO ₂ scaffolds exhibit superior capacity in enhancing cell activity, improving osteogenesis-related gene expressions, and inducing cell mineralization compared with PLLA and PLLA/Fe ₃ O ₄ scaffolds. Conclusion: In short, the Fe ₃ O ₄ @SiO ₂ nanochains endow scaffolds with good magnetism and cytocompatibility, which have great potential in accelerating bone repair.

Fe is considered as a potential candidate for implantmaterials, but its application is impeded by the low degradationrate. Herein, a dual-phase Fe30Mn6Si alloy was prepared bymechanical alloying (MA). During MA, the motion of dislocationsdriven by the impact stress promoted the solid solution of Mn inFe, which transformed alpha-ferrite into gamma-austenite since Mn was anaustenite-stabilizing element. Meanwhile, the incorporation of Sidecreased the stacking fault energy inside austenite grains, whichtangled dislocations into stacking faults and acted as nucleationsites for epsilon-martensite. Resultantly, Fe30Mn6Si powder had a dual-phase structure composed of 53%gamma-austenite and 47%epsilon-martensite. Afterward, the powders were prepared into implantsby selective laser melting. The Fe30Mn6Si alloy had a morenegative corrosion potential of-0.76 +/- 0.09 V and a higher corrosion current of 30.61 +/- 0.41 mu A/cm2than Fe and Fe30Mn.Besides, the long-term weight loss tests also proved that Fe30Mn6Si had the optimal degradation rate (0.25 +/- 0.02 mm/year)

Background: Fe₃O₄ nanoparticles are highly desired for constructing endogenous magnetic microenvironment in scaffold to accelerate bone regeneration due to their superior magnetism. However, their random arrangement easily leads to mutual consumption of magnetic poles, thereby weakening the magnetic stimulation effect. Methods: In this study, magnetic nanochains are synthesized by magnetic-field-guided interface co-assembly of Fe₃O₄ nanoparticles. In detail, multiple Fe₃O₄ nanoparticles are aligned along the direction of magnetic force lines and are connected in series to form nanochain structures under an external magnetic field. Subsequently, the nanochain structures are covered and fixed by depositing a thin layer of silica (SiO₂), and consequently forming linear magnetic nanochains (Fe₃O₄@SiO₂). The Fe₃O₄@SiO₂ nanochains are then incorporated into poly l-lactic acid (PLLA) scaffold prepared by selective laser sintering technology.Results: The results show that the Fe₃O₄@SiO₂ nanochains with unique core-shell structure are successfully constructed. Meanwhile, the orderly assembly of nanoparticles in the Fe₃O₄@SiO₂ nanochains enable to form magnetic energy coupling and obtain a highly magnetic micro-field. The in vitro tests indicate that the PLLA/Fe₃O₄@SiO₂ scaffolds exhibit superior capacity in enhancing cell activity, improving osteogenesis-related gene expressions, and inducing cell mineralization compared with PLLA and PLLA/Fe₃O₄ scaffolds. Conclusion: In short, the Fe₃O₄@SiO₂ nanochains endow scaffolds with good magnetism and cytocompatibility, which have great potential in accelerating bone repair.

Magnesium ion (Mg²⁺)‐based materials are known to exert osteogenic effects that can be enhanced by the bioelectrical properties of magnetic fields. In this study, we examined the effect of a medium‐strength static magnetic field (SMF), combined with a Mg²⁺‐containing medium, on the proliferation and osteogenic differentiation of mouse bone marrow mesenchymal stem cells (BMSCs). Mouse BMSCs were divided into a control group, 7.5 mM Mg²⁺ group, 15 mT SMF group, and 7.5 mM Mg²⁺ plus 15 mT SMF group. Osteoblast proliferation was measured using a Cell Counting Kit‐8 assay, whereas osteogenic differentiation was detected using alkaline phosphatase (ALP) staining and western blot analysis, respectively. The number and size of calcium nodules were determined using Alizarin Red staining. Compared with those in the control group, the ALP activity, calcium nodule formation, and osteogenic protein expression were promoted in other groups. In particular, Mg²⁺‐SMF had a significant effect after 7 days of intervention and more effectively promoted BMSC differentiation and proliferation than either Mg²⁺ or the SMF alone, suggesting that Mg²⁺‐SMF synergistically contributed to osteogenic differentiation and cell proliferation. To examine their roles in bone differentiation, the Magt1 and Creb1 genes were silenced in BMSCs, and the findings indicated that the synergistic intervention with Mg²⁺ and magnetic fields might exert osteogenic effects via the MAGT1 channel and CREB1 protein. This study provides an experimental basis for a potential Mg²⁺‐SMF synergistic artificial bone material that could be clinically applied in the treatment of bone defects.