Pitt | Swanson Engineering
Ultra-High Ductility (UHD) Magnesium Alloy Based Stents

Ultra-High Ductility (UHD) Magnesium Alloy Based Stents

Magnesium alloy based stents have emerged as another biodegradable stent candidate in the past 10 years. Extensive studies that have been conducted report the exploration of different magnesium alloys as novel biodegradable metallic materials for stent application. However, the ductility limitation of magnesium alloy has been a key issue for biodegradable stents applications. Currently, no magnesium alloy based stents have demonstrated similar expansion capability to currently available permanent stents made of bio-inert metallic alloys. The goal of the proposed work was to develop a new magnesium alloy system which addresses the limited ductility of current magnesium systems and to evaluate the feasibility of the proposed magnesium alloy system in the form of prototype tracheal stent devices in clinically relevant animal models. Various biocompatible alloying elements determined by first principles theory were used to synthesize UHD alloys. Tensile test results showed that the Mg-Li alloys displayed lower strength, but higher ductility compared to AZ31 measured by elongation at fracture. Balloon expandable tracheal stents were designed using biodegradable Mg-Li (LZ61) alloys due to its excellent biomechanical and ductility properties compared to commercially available Mg alloy. Further, LZ61 exhibits low in-vivo and in-vitro corrosion rates providing sufficient mechanical support during the entire healing process eliminating pre-mature tracheal collapse, Moreover, Li, and other elements are selected as alloying elements due to their proven safety profiles.

Ultra-High Ductility (UHD) Magnesium Alloy Based Stents

Airway endoscopy images at time of stent insertion and post-implantation. 

 

  1. ACS BIOMATERIALS SCIENCE & ENGINEERING, 2018, 4(3): p. 919-932 (2018).
  2. ULTRAHIGH DUCTILITY, NOVEL Mg-Li BASED ALLOYS FOR BIOMEDICAL APPLICATIONS, WO2016094510A1, PCT/US2015/064694 (2014).
  3. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, 102(3): p. 611-620 (2014).