Microalloying Design of Biodegradable Mg–2Zn–0.05Ca Promises Improved Bone-Implant Applications

Abstract

Mg and its alloys have been comprehensively studied and show huge potential for clinical orthopedic applications. However, balancing the mechanical strength and corrosion resistance of alloys is still a challenge. In light of this, micro-level contents of Zn and Ca were added to pure Mg to fabricate a Mg−2Zn−0.05Ca microalloy to expectedly enhance the mechanical strength and concurrently improve the corrosion resistance. The characteristics of the rolled Mg−2Zn−0.05Ca microalloy were explored using optical microscopy, X-ray diffraction, and tensile tests. The corrosion behavior and mechanical strength loss were explored using electrochemical and immersion tests. The effects of the microalloy extract on the proliferation, adhesion, and osteogenic differentiation of MC3T3-E1 cells were systematically studied. Moreover, implantations were done in femoral condyles of rabbits to study the degradation properties, osteogenic effect, mechanical strength loss, and biosafety of the microalloy. The ultimate tensile strength and yield strength of the rolled microalloy were found to be significantly elevated to 257 ± 2.74 and 237.6 ± 8.29 MPa, respectively. The microalloy showed a stable and gradual strength loss during degradation, both in vivo and in vitro. Concurrently, the microalloy exhibited improved corrosion resistance ability and especially, in vivo, the rolled microalloy exhibited a comparable degradation rate to that of rolled pure Mg within the initial 12 weeks of implantation. Additionally, the microalloy promoted osteogenesis, both in vitro and in vivo, and no short-and long-term toxicities of the microalloy were observed in rabbits. This study suggested that the rolled Mg−2Zn−0.05Ca microalloy effectively balanced the mechanical strength and corrosion resistance and showed potential application as bone implants.

Integrated Zr‐MOF/NH4TiOF3Bilayer Coating on Magnesium for Controllable Corrosion, Cytocompatibility, and Drug Delivery Multifunctionalities

“…The UiO/NTiF coated Mg is able to retain the long‐term mechanical integrity, owing to the highly effective corrosion protection of NTiF layer and UiO membrane, which could satisfy the requirements of most fractures, including the hand, femur, and distal radius fractures requiring mechanical support up to 3 months. [ 55 ]…”

In vivo performance of a rare earth free Mg–Zn–Ca alloy manufactured using twin roll casting for potential applications in the cranial and maxillofacial fixation devices

“…In general, all these alloys exhibit new bone formation, no sign of inflammation or adverse effects to the soft tissue adjacent to the implant or the degradation product and these alloys also promote bone healing. Among these Mg based alloys, Mg–Zn–Ca alloy shown particularly attractive characteristics as bone implant materials for the promotion osteogenesis [ 108 ] and antimicrobial properties [ 109 ]. As the degrading implant generate Mg 2+ as corrosion product, Mg 2+ could up-regulate the osteoblastic activity of osteoblasts by activating the signal pathways to promote the proliferation and osteogenic differentiation [ 110 , 111 ].…”

In Vivo Degradation Behavior of Magnesium Alloy for Bone Implants with Improving Biological Activity, Mechanical Properties, and Corrosion Resistance

“…Magnesium (Mg) alloys are used to make several artificial human body parts and implants, such as substitutes for hard tissue replacement, fracture healing aids, and fixation devices, because of their light weight, excellent mechanical properties, biocompatibility, and biodegradability [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Implanted devices often suffer from corrosion because they are exposed to the surrounding body fluids, which typically have high ionic strength.…”