Opportunities and challenges for the biodegradable magnesium alloys as next-generation biomaterials

Abstract

In recent years, biodegradable magnesium alloys emerge as a new class of biomaterials for tissue engineering and medical devices. Deploying biodegradable magnesium-based materials not only avoids a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials are often subjected to an uncontrolled and fast degradation, acute toxic responses and rapid structural failure presumably due to a localized, too rapid corrosion process. The patented Mg–Nd–Zn–based alloys (JiaoDa BioMg [JDBM]) have been developed in Shanghai Jiao Tong University in recent years. The alloy series exhibit lower biodegradation rate and homogeneous nanophasic degradation patterns as compared with other biodegradable Mg alloys. The in vitro cytotoxicity tests using various types of cells indicate excellent biocompatibility of JDBM. Finally, bone implants using JDBM-1 alloy and cardiovascular stents using JDBM-2 alloy have been successfully fabricated and in vivo long-term assessment via implantation in animal model have been performed. The results confirmed the reduced degradation rate in vivo, excellent tissue compatibility and long-term structural and mechanical durability. Thus, this novel Mg-alloy series with highly uniform nanophasic biodegradation represent a major breakthrough in the field and a promising candidate for manufacturing the next generation biodegradable implants.

Novel Bio-functional Magnesium Coating on Porous Ti6Al4V Orthopaedic Implants: In vitro and In vivo Study

“…Importantly, it was found that magnesium could influence bone tissue growth positively, which could improve the bone healing and reconstruction2930. Witte et al .…”

Microstructure, biodegradable behavior in different simulated body fluids, antibacterial effect on different bacteria and cytotoxicity of rolled Zn–Li–Ag alloy

“…Its degradation rate is about 10-20 μm year −1 [3], which solves the problem of excessive degradation rate of magnesium alloy [4,5]. The corrosion rate of zinc is appropriate, but the mechanical properties of cast pure Zn are poor, and the tensile strength is less than 20 MPa, which is far lower than the biomedical standards [6]. The mechanical properties and corrosion resistance of pure zinc can be improved through alloying and plastic deformation to meet the requirements of medical implantable materials [7].…”

In vitro and in vivo studies on as-extruded Mg- 5.25wt.%Zn-0.6wt.%Ca alloy as biodegradable metal

“…Aluminum (Al) and rare earth elements (REEs) were usually used to elevate the strength of magnesium and to reduce the corrosion rate. Some Aland REEs-containing alloys, such as AZ91 [10], LAE442 [10,11], WZ21 [12] and Mg-Nd-Zn-Zr [13], were tested. Al is a well-known neurotoxicant and associated with dementia and Alzheimer's disease [14].…”

“…The yield strength ranged in 130-250 MPa, tensile strength ranged in 220-330 MPa and the elongation ranged in 12%-27% [23,24]. The mechanical properties meet the requirements of magnesium alloys for bone use [13]. The purpose of this study is to investigate the in vitro and in vivo corrosion as well as the biocompatibility of Mg-5.25Zn-0.6Ca alloy to take further insight into the feasibility for orthopedic application.…”