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Porous biodegradable Mg and its alloys are considered to have a great potential to serve as ideal bone substitutes. The recent progress in additive manufacturing (AM) has prompted its application to fabricate Mg scaffolds with geometrically ordered porous structures. Extrusion-based AM, followed by debinding and sintering, has been recently demonstrated as a powerful approach to fabricating such Mg scaffolds, which can avoid some crucial problems encountered when applying powder bed fusion AM techniques. However, such pure Mg scaffolds exhibit a too high rate of in vitro biodegradation. In the present research, alloying through a pre-alloyed Mg-Zn powder was ultilized to enhance the corrosion resistance and mechanical properties of AM geometrically ordered Mg-Zn scaffolds simultaneously. The in vitro biodegradation behavior, mechanical properties, and electrochemical response of the fabricated Mg-Zn scaffolds were evaluated. Moreover, the response of preosteoblasts to these scaffolds was systematically evaluated and compared with their response to pure Mg scaffolds. The Mg-Zn scaffolds with a porosity of 50.3% and strut density of 93.1% were composed of the Mg matrix and MgZn2 second phase particles. The in vitro biodegradation rate of the Mg-Zn scaffolds decreased by 81% at day 1, as compared to pure Mg scaffolds. Over 28 days of static immersion in modified simulated body fluid, the corrosion rate of the Mg-Zn scaffolds decreased from 2.3 ± 0.9 mm/y to 0.7 ± 0.1 mm/y. The yield strength and Young's modulus of the Mg-Zn scaffolds were about 3 times as high as those of pure Mg scaffolds and remained within the range of those of trabecular bone throughout the biodegradation tests. Indirect culture of MC3T3-E1 preosteoblasts in Mg-Zn extracts indicated favorable cytocompatibility. In direct cell culture, some cells could spread and form filopodia on the surface of the Mg-Zn scaffolds. Overall, this study demonstrates the great potential of the extrusion-based AM Mg-Zn scaffolds to be further developed as biodegradable bone-substituting biomaterials.

Porous biodegradable Mg and its alloys are considered to have a great potential to serve as ideal bone substitutes. The recent progress in additive manufacturing (AM) has prompted its application to fabricate Mg scaffolds with geometrically ordered porous structures. Extrusion-based AM, followed by debinding and sintering, has been recently demonstrated as a powerful approach to fabricating such Mg scaffolds, which can avoid some crucial problems encountered when applying powder bed fusion AM techniques. However, such pure Mg scaffolds exhibit a too high rate of in vitro biodegradation. In the present research, alloying through a pre-alloyed Mg-Zn powder was ultilized to enhance the corrosion resistance and mechanical properties of AM geometrically ordered Mg-Zn scaffolds simultaneously. The in vitro biodegradation behavior, mechanical properties, and electrochemical response of the fabricated Mg-Zn scaffolds were evaluated. Moreover, the response of preosteoblasts to these scaffolds was systematically evaluated and compared with their response to pure Mg scaffolds. The Mg-Zn scaffolds with a porosity of 50.3% and strut density of 93.1% were composed of the Mg matrix and MgZn 2 second phase particles. The in vitro biodegradation rate of the Mg-Zn scaffolds decreased by 81% at day 1, as compared to pure Mg scaffolds. Over 28 days of static immersion in modified simulated body fluid, the corrosion rate of the Mg-Zn scaffolds decreased from 2.3 ± 0.9 mm/y to 0.7 ± 0.1 mm/y. The yield strength and Young's modulus of the Mg-Zn scaffolds were about 3 times as high as those of pure Mg scaffolds and remained within the range of those of trabecular bone throughout the biodegradation tests. Indirect culture of MC3T3-E1 preosteoblasts in Mg-Zn extracts indicated favorable cytocompatibility. In direct cell culture, some cells could spread and form filopodia on the surface of the Mg-Zn scaffolds. Overall, this study demonstrates the great potential of the extrusion-based AM Mg-Zn scaffolds to be further developed as biodegradable bone-substituting biomaterials. [ABSTRACT FROM AUTHOR]

The production of magnesium-zinc (Mg-Zn) alloy spherical powders is complex and expensive. As they have extensive applications in a wide variety of fields including military manufacturing, aerospace, and biomedicine, there is an urgent need to explore new production processes for Mg-Zn alloy spherical powders. In this study, 5 wt% homogenised Mg-Zn alloy spherical powder was prepared using the relative vacuum method. The effects of the insulation time, maximum temperature, and heating rate on the morphology, size distribution, and particle size of the Mg-Zn alloy spherical powder were investigated. The results indicated that the insulation time had the greatest influence on the particle size of the spherical powder, whereas the maximum temperature and heating rate had significant impacts on the alloy composition. When the insulation time was 10 min the maximum temperature was 1150 °Cand the heating rate was 15 min, the prepared Mg-Zn alloy spherical powder exhibited a full morphology without satellite particles, uniform composition, narrow size distribution, and a volume median diameter (VMD) of 17.62 μm. The research findings provide a new production process for Mg-Zn alloy spherical powders and establish a foundation for studying the specific effects of temperature on the production of Mg-Zn alloy spherical powders using the relative vacuum method. • The relative vacuum method is used to prepare Mg-Zn alloy spherical powder, with uniform composition and high sphericity, and the particle size is suitable for the preparation of high-end materials such as powder metallurgy. • The effects of holding time, maximum temperature and heating rate on the composition, size and morphology of Mg-Zn alloy spheres were investigated, and the optimal process conditions were found, including insulation time of 10 min, maximum temperature of 1150 °Cand heating ratio of 15 min. • The surface of Mg-Zn alloy spherical powder was characterized by SEM and TEM. [ABSTRACT FROM AUTHOR]

Gelatin methacryloyl (GelMA) has been widely used in bone engineering. It can also be filled into the calvarial defects with irregular shape. However, lack of osteoinductive capacity limits its potential as a candidate repair material for calvarial defects. In this study, we developed an injectable magnesium–zinc alloy containing hydrogel complex (Mg-IHC), in which the alloy was fabricated in an atomization process and had small sphere, regular shape, and good fluidity. Mg-IHC can be injected and plastically shaped. After cross-linking, it contents the elastic modulus similar to GelMA, and has inner holes suitable for nutrient transportation. Furthermore, Mg-IHC showed promising biocompatibility according to our evaluations of its cell adhesion, growth status, and proliferating activity. The results of alkaline phosphatase (ALP) activity, ALP staining, alizarin red staining, and real-time polymerase chain reaction (PCR) further indicated that Mg-IHC could significantly promote the osteogenic differentiation of MC3T3-E1 cells and upregulate the genetic expression of collagen I (COL-I), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2). Finally, after applied to a mouse model of critical-sized calvarial defect, Mg-IHC remarkably enhanced bone formation at the defect site. All of these results suggest that Mg-IHC can promote bone regeneration and can be potentially considered as a candidate for calvarial defect repairing.

A magnesium-zinc alloy rod was implanted into the marrow cavity of the distal femur in New Zealand rabbits. The femur with the implanted alloy was compared with the contralateral femur in which a bone tunnel without implant was formed as a control. Degradation of the magnesium-zinc alloy was analyzed via X-ray, scanning electron microscopy, and element energy spectrum analysis. Serum magnesium, liver and kidney function tests, and myocardial enzymes were measured. Heart, liver, kidney and spleen were sectioned for pathological analysis, and the effects of the implanted material on the histology and function of important organs were analyzed. Magnesium-zinc alloy was resorbed from the bone marrow cavity of the femur; 87% of the alloy was degraded within 14 weeks after the surgery. There were no significant differences in serum magnesium, liver or kidney function tests, or myocardial enzymes before the surgery and after degradation of the magnesium-zinc alloy. Histology of the heart, liver, kidney, and spleen did not change. This study demonstrated that magnesium-zinc alloy can be resorbed in bone, and that the degradation products have good biocompatibility with heart, liver, kidney, and spleen. [ABSTRACT FROM AUTHOR]

Zn is an eco-friendly element with high solid solubility (6.2 wt%) in Mg. In this research, four hypoeutectic Mg-xZn (x = 2, 4, 6, and 15 wt%) binary alloys are systematically investigated as anode materials for Magnesium-air (Mg-air) battery. The self-corrosion and battery discharge behavior of these four hypoeutectic Mg–Zn alloys are analyzed by electrochemical measurements and half-cell discharge tests. The results show that the addition of 2 wt% Zn significantly improves the anodic efficiency and specific capacity of Mg, while addition of 6 wt% and 15 wt% Zn reduces its discharge properties. It is due to the large volume fraction of Mg 7 Zn 3 and Mg 4 Zn 7 intermetallic phases act as cathode accelerating the self-corrosion of alloy anode. Mg-2 wt.% Zn alloy anode has the best battery performance with 54.42% utilization efficiency and 1185.50 mA h g−1 specific capacity at 10 mA cm−2, and has the highest specific energy density 1140.1 mW h g−1 at 2 mA cm−2. • Effect of Zn on microstructure and discharge properties of Mg anode in Mg-air battery was investigated. • Addition of 2 wt% Zn significantly improves the anodic efficiency and specific capacity of Mg anode. • Battery performance of Mg-Zn alloy anodes depend on Mg x Zn y intermetallic phase. [ABSTRACT FROM AUTHOR]

Gelatin methacryloyl (GelMA) has been widely used in bone engineering. It can also be filled into the calvarial defects with irregular shape. However, lack of osteoinductive capacity limits its potential as a candidate repair material for calvarial defects. In this study, we developed an injectable magnesium-zinc alloy containing hydrogel complex (Mg-IHC), in which the alloy was fabricated in an atomization process and had small sphere, regular shape, and good fluidity. Mg-IHC can be injected and plastically shaped. After cross-linking, it contents the elastic modulus similar to GelMA, and has inner holes suitable for nutrient transportation. Furthermore, Mg-IHC showed promising biocompatibility according to our evaluations of its cell adhesion, growth status, and proliferating activity. The results of alkaline phosphatase (ALP) activity, ALP staining, alizarin red staining, and real-time polymerase chain reaction (PCR) further indicated that Mg-IHC could significantly promote the osteogenic differentiation of MC3T3-E1 cells and upregulate the genetic expression of collagen I (COL-I), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2). Finally, after applied to a mouse model of critical-sized calvarial defect, Mg-IHC remarkably enhanced bone formation at the defect site. All of these results suggest that Mg-IHC can promote bone regeneration and can be potentially considered as a candidate for calvarial defect repairing., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Wang, Wang, Zhao, Yan, Huang, Yin, Huang, Chen and Zhu.)