title: A Zr-based bulk metallic glass for future stent applications: Materials properties, finite element modeling, and in vitro human vascular cell response.
abstract: Despite the prevalent use of crystalline alloys in current vascular stent technology, new biomaterials are being actively sought after to improve stent performance. In this study, we demonstrated the potential of a Zr-Al-Fe-Cu bulk metallic glass (BMG) to serve as a candidate stent material. The mechanical properties of the Zr-based BMG, determined under both static and cyclic loadings, were characterized by high strength, which would allow for the design of thinner stent struts to improve stent biocompatibility. Finite element analysis further complemented the experimental results and revealed that a stent made of the Zr-based BMG was more compliant with the beats of a blood vessel, compared with medical 316L stainless steel. The Zr-based BMG was found to be corrosion resistant in a simulated body environment, owing to the presence of a highly stable ZrO2-rich surface passive film. Application-specific biocompatibility studies were conducted using human aortic endothelial cells and smooth muscle cells. The Zr-Al-Fe-Cu BMG was found to support stronger adhesion and faster coverage of endothelial cells and slower growth of smooth muscle cells than 316L stainless steel. These results suggest that the Zr-based BMG could promote re-endothelialization and potentially lower the risk of restenosis, which are critical to improve vascular stent implantation integration. In general, findings in this study raised the curtain for the potential application of BMGs as future candidates for stent applications.
  
  
  CONCLUSIONS
  Vascular stents are medical devices typically used to restore the lumen of narrowed or clogged blood vessel. Despite the clinical success of metallic materials in stent-assisted angioplasty, post-surgery complications persist due to the mechanical failures, corrosion, and in-stent restenosis of current stents. To overcome these hurdles, strategies including new designs and surface functionalization have been exercised. In addition, the development of new materials with higher performance and biocompatibility can intrinsically reduce stent failure rates. The present study demonstrates the advantages of a novel material, named bulk metallic glass (BMG), over the benchmarked 316L stainless steel through experimental methods and computational simulations. It raises the curtain of new research endeavors on BMGs as competitive alternatives for stent applications.
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2100, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2100, USA.
authors.forename: Chao
authors.initials: C
authors.lastname: Pu
authors.affiliation: Department of Surgery, The University of Tennessee Graduate School of Medicine, Knoxville, TN 37920, USA.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Fisher
authors.affiliation: Department of Surgery, The University of Tennessee Graduate School of Medicine, Knoxville, TN 37920, USA.
authors.forename: Deidra J H
authors.initials: DJ
authors.lastname: Mountain
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2100, USA.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2100, USA.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Liaw
authors.affiliation: School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2100, USA; Department of Mechanical, Aerospace and Biomedical Engineering, The University of Tennessee, Knoxville, TN 37996-2210, USA. Electronic address: whe5@utk.edu.
authors.forename: Wei
authors.initials: W
authors.lastname: He
mesh_terms: D001011:Aorta / Q000166:cytology*; D002448:Cell Adhesion / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003343:Corrosion; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects; D020342:Finite Element Analysis; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D055595:Mechanical Phenomena / Q000187:drug effects; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects; D056951:Photoelectron Spectroscopy; D013193:Stainless Steel / Q000494:pharmacology; D015607:Stents; D013314:Stress, Mechanical; D013499:Surface Properties; D015040:Zirconium / Q000494:pharmacology*
chemical_list: D013193:Stainless Steel; D015040:Zirconium
keywords: Biocompatibility; Bulk metallic glass; Corrosion; Mechanical properties; Stent