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For high corrosion resistance and extensively modified biodegradable Mg-based alloys and composites for bone implants, a new Mg-based matrix model prepared by powder metallurgy is discussed and developed. In this research, Mg-5 wt.%Zn alloys were selected as a case. And they were impacted by hot extrusion and aging treatments to construct microstructure with different characteristics. Their self-forming corrosion product layer in Ringer's solution, biodegradable behavior and corrosion mechanism were minutely investigated by in vitro degradation, electrochemical corrosion and cytocompatibility. The results demonstrated the extruded Mg-5 wt.%Zn alloy aged for 96 h showed high corrosion resistance, good biocompatibility for L929 and excellent ability of maintaining sample integrity during the immersion. Significantly, the alloy showed fine-grain microstructure and uniform distributed hundred nano-sized second phases, which promoted the formation of the uniform and smooth corrosion product layer at the beginning of immersion. The corrosion product layer was more stable in chloride containing aqueous solution and could be directly formed and repaired quickly, which effectively protected the matrix from further corrosion. In addition, an ideal model of Mg-based matrix for bone tissue engineering was tried to presume and propose by discussing the causal relationship between microstructure and bio-corrosion process. [ABSTRACT FROM AUTHOR]

Mg-6%Zn-10%Ca 3 (PO 4 ) 2 composite was prepared through powder metallurgy methods with polycaprolactone(PCL) coating on its surface. The properties of the PCL coatings on the surface of Mg-6%Zn-10%Ca 3 (PO 4 ) 2 composite, such as surface morphology, the corrosion behavior and the cytotoxicity properties were investigated. The results show that PCL coating improves the corrosion resistance of the magnesium matrix composite specimens significantly. Mg-6%Zn-10%Ca 3 (PO 4 ) 2 composite specimens with PCL coating exhibit good corrosion resistance and low pH values in SBF at 37 °C in the immersion test, as compared with uncoated specimens. The cytotoxicity tests indicate Mg-6%Zn-10%Ca 3 (PO 4 ) 2 with PCL coating is nontoxic with higher relative growth rate than that of uncoated composites against L-929 cells. [ABSTRACT FROM AUTHOR]

Abstract: In this study 5, 10 and 15% β-Ca3(PO4)2/Mg–Zn composites were prepared through powder metallurgy methods, and their corrosion behavior and mechanical properties were studied in simulated body fluid (SBF) at 37°C. The 10% β-Ca3(PO4)2/Mg–Zn composite was selected for cytocompatibility assessment and in vivo biodegradation testing. The results identified the α-Mg, MgZn and β-Ca3(PO4)2 phases in these sintered composites. The density and elastic modulus of the β-Ca3(PO4)2/Mg–6% Zn composite match those of natural bone, and the strength is approximately double that of natural bone. The 10% β-Ca3(PO4)2/Mg–6% Zn composites exhibit good corrosion resistance, as determined by a 30day immersion test and electrochemical measurements in SBF at 37°C. The 10% β-Ca3(PO4)2/Mg–6% Zn composite is safe for cellular applications, with a cytotoxicity grade of ∼0–1 against L929 cells in in vitro testing. The β-Ca3(PO4)2/Mg–6% Zn composite also exhibits good biocompatibility with the tissue and the important visceral organs the heart, kidney and liver of experimental rabbits. The composite has a suitable degradation rate and improves the concrescence of a pre-broken bone. The corrosion products, such as Mg(OH)2 and Ca5(PO4)6(OH)2, can improve the biocompatibility of the β-Ca3(PO4)2/Mg–Zn composite. [Copyright &y& Elsevier]

• Zn-0.5Ti alloy prepared by powder metallurgy has fine grain size. • The primary cell effect formed Zn-0.5Ti alloy a faster corrosion degradation rate. • The addition of Ti to Zn increases the mechanical properties. • Zn-0.5Ti alloy GBR membrane has great biocompatibility. • Zn-0.5Ti alloy GBR membrane has good osteogenic properties. The Zn-0.5Ti alloy bone regeneration membranes, prepared via powder metallurgy, hot extrusion, and hot rolling, exhibit robust mechanical properties (tensile strength: 122.5 ± 1.8 MPa, elongation: 18.3 ± 0.7 %), appropriate degradation rate (0.127 mm/year in SBF solution), and good biocompatibility (cytotoxicity grade 0–1). After 4 and 8 weeks of implantation, the alloy showed significant bone growth (bone volume ratios (BV/TV): 11.3 ± 1.8 % and 23.1 ± 3.5 %, respectively, measured by Micro-CT), indicating promising potential as a GBR membrane material. [ABSTRACT FROM AUTHOR]

In this study, 10%β-Ca 3 (PO 4 ) 2 /Mg-6%Zn (wt.%) composites with Mg-6%Zn alloy as control were prepared by powder metallurgy. After hot extrusion, the as-extruded composites were aged for 72 h at 150 °C. The effects of the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment on their microstructure, mechanical properties and corrosion resistance were investigated. The XRD results identified α-Mg, MgZn phase and β-Ca 3 (PO 4 ) 2 phase in these composites. After hot extrusion, grains were significantly refined, and the larger-sized β-Ca 3 (PO 4 ) 2 particles and coarse MgZn phases were broken into linear-distributed β-Ca 3 (PO 4 ) 2 and MgZn phases along the extrusion direction. After aging treatment, the elements of Zn, Ca, P and O presented a more homogeneous distribution. The compressive strengths of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites were approximately double those of natural bone, and their densities and elastic moduli matched those of natural bone. The immersion tests and electrochemical tests revealed that the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment could promote the formation of protective corrosion product layer on the sample surface in Ringer's solution, which improved corrosion resistance of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites. The XRD results indicated that the corrosion product layer contained Mg(OH) 2 , β-Ca 3 (PO 4 ) 2 and hydroxyapatite (HA). The cytotoxicity assessments showed the as-extruded β-Ca 3 (PO 4 ) 2 /Mg-Zn composite aged for 72 h was harmless to L-929 cells. These results suggested that the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites prepared by powder metallurgy were promising to be used for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Magnesium alloys have been regarded as potential degradable biomedical materials due to their suitable mechanical properties and excellent biocompatibility. In this study, Mg-Zn alloys were fabricated by powder metallurgy and then hot extruded. The effects of Zn concentration and heat treatment on their microstructure, mechanical properties and corrosion behavior were investigated. The compression test results showed that their mechanical properties were suitable for bone tissue engineering. The corrosion behavior of Mg-Zn alloys was analyzed by immersion tests and electrochemical tests in Ringer's solution. The results revealed that the increasing Zn concentration reduced the corrosion potential but increased corrosion current because severe micro-galvanic corrosion was caused by more large-size intermetallic phases. Although solid solution treatment could reduce intermetallic phase amounts, it caused micropores on the surface. And these micropores could resulted in the pitting corrosion and reduce the corrosion resistance. Notably, aging treatment could reduce the segregation of Zn and promote the compactness and uniformity of corrosion product layer on the surface, leading to the improvement of corrosion resistance. In addition, the as-extruded Mg-6%Zn alloy (wt.%) aged for 72 h was harmless to L-929 cells in cytotoxicity test. Consequently, the as-extruded Mg-Zn alloys prepared by powder metallurgy are promising to develop to be ideal biodegradable implants for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: A Mg-6%Zn-15%Ca3(PO4)2 composite is produced through powder metallurgy method in this study to investigate it’s in vivo biocompatibility and biodegradation in Zelanian rabbits. The metal ion concentrations in the rabbit blood are detected and the muscle, heart, liver and kidneys tissues are inspected for histomorphology analysis. The composite is implanted and fastened with the rabbit's pre-broken femoral shaft to observe the biodegradation process. The results show that The Mg2+, Zn2+, Ca2+ ions are in the normal range in the animal's blood during the whole experiment period. All the tissues are normal during the composite degradation process, which indicates the composite exhibits good biocompatibility to these visceral organs. The biodegradation of composite is benefit to stimulate the bone formation around the pre-fracture. [Copyright &y& Elsevier]