Research Progress in Biodegradable Metals for Stent Application

During the last two decades, a great amount of researches have been focused on biodegradable metals. Technologies from alloy design to melting, manufacturing and processing, from microtube to stent laser processing and drug eluting coating have been improved and optimized continuously. Biodegradable metallic stent has evolved from a concept to a real product and generated three branches of material system. A large amount of animal tests and clinical tests have been carried out to investigate biodegradable magnesium stents. Results of clinical study have indicated that the magnesium stent is feasible, with favourable safety and performance outcomes. More importantly, Biotronik won CE Mark for Magmaris bioresorbable stent in 2016. Researches of biodegradable iron stents are still in the stage of animal tests. The nitrided iron stent possesses excellent mechanical properties. Results showed a good long-term biocompatibility of nitrided iron stent in rabbit and porcine model. Biodegradable zinc stent has only been introduced in recent years. Only a few in vivo studies have been reported with zinc wires implanted in rats. Results showed a good degradation behavior and biocompatibility of zinc wires. In this paper, the current research status of biodegradable metallic stents is reviewed, and the future research and development in mechanical property optimization, drug eluting and intelligence is proposed.