Biodegradable Metals for Cardiovascular Stent Application: Interests and New Opportunities

Abstract

During the last decade, biodegradable metallic stents have been developed and investigated as alternatives for the currently-used permanent cardiovascular stents. Degradable metallic materials could potentially replace corrosion-resistant metals currently used for stent application as it has been shown that the role of stenting is temporary and limited to a period of 6–12 months after implantation during which arterial remodeling and healing occur. Although corrosion is generally considered as a failure in metallurgy, the corrodibility of certain metals can be an advantage for their application as degradable implants. The candidate materials for such application should have mechanical properties ideally close to those of 316L stainless steel which is the gold standard material for stent application in order to provide mechanical support to diseased arteries. Non-toxicity of the metal itself and its degradation products is another requirement as the material is absorbed by blood and cells. Based on the mentioned requirements, iron-based and magnesium-based alloys have been the investigated candidates for biodegradable stents. This article reviews the recent developments in the design and evaluation of metallic materials for biodegradable stents. It also introduces the new metallurgical processes which could be applied for the production of metallic biodegradable stents and their effect on the properties of the produced metals.

Comparative mechanical and corrosion studies on magnesium, zinc and iron alloys as biodegradable metals

“…[4][5][6][7][8][9][10] Iron is also an essential element for proper biological functions, mainly for the transfer of oxygen by blood. 13 The recommended daily value of Fe is about 10 mg. 6 Regarding the biocompatibility of iron-based alloys, there are a number of reported results, [14][15][16] but they are often controversial. In order to explain the discrepancies between biocompatibility tests, more in-vitro and in-vivo experiments are needed.…”

“…Appropriate alloying of Mg, Zn and Fe can positively modify their mechanical, corrosion and physical properties, which are important for potential medical applications. In the available literature many alloying elements are proposed for these purposes, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] but in this study Mg-RE (RE = rare earth metals, Gd, Nd, Y), Zn-Mg and Fe-Mn based alloys were selected, because all these alloying systems are generally considered as relatively safe and acceptable for a potential medical use. 3 …”

Silk-based resorbable electronic devices for remotely controlled therapy and in vivo infection abatement

“…Recent studies have demonstrated a class of completely watersoluble and fully resorbable silicon-based components (9), shedding light on biodegradable devices (10) with integrated functions that go well beyond those historically offered by resorbable sutures (11), degradable intravascular stents (12,13), and matrices for drug release (14,15). A particular challenge for medical applications is how to externally control such devices and correlate this control with device degradation time, including the electronics and biomaterial support layers.…”

Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

“…Biodegradable metals corrode and disappear after implantation. This eliminates the need for a subsequent, second surgery to remove the implant or device, as well as lowering the risk of infection and foreign body reaction [8][9][10][11][12]. Mg based implants have experienced good clinical successes in recent years [13][14][15][16][17].…”