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Published March 8, 2018 | Published + Supplemental Material
Journal Article Open

Tube Expansion Deformation Enables In Situ Synchrotron X-ray Scattering Measurements during Extensional Flow-Induced Crystallization of Poly l-Lactide Near the Glass Transition

Abstract

Coronary Heart Disease (CHD) is one of the leading causes of death worldwide, claiming over seven million lives each year. Permanent metal stents, the current standard of care for CHD, inhibit arterial vasomotion and induce serious complications such as late stent thrombosis. Bioresorbable vascular scaffolds (BVSs) made from poly l-lactide (PLLA) overcome these complications by supporting the occluded artery for 3–6 months and then being completely resorbed in 2–3 years, leaving behind a healthy artery. The BVS that recently received clinical approval is, however, relatively thick (~150 µm, approximately twice as thick as metal stents ~80 µm). Thinner scaffolds would facilitate implantation and enable treatment of smaller arteries. The key to a thinner scaffold is careful control of the PLLA microstructure during processing to confer greater strength in a thinner profile. However, the rapid time scales of processing (~1 s) defy prediction due to a lack of structural information. Here, we present a custom-designed instrument that connects the strain-field imposed on PLLA during processing to in situ development of microstructure observed using synchrotron X-ray scattering. The connection between deformation, structure and strength enables processing–structure–property relationships to guide the design of thinner yet stronger BVSs

Additional Information

© 2018 The Author(s). Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0). Received: 11 February 2018 / Revised: 4 March 2018 / Accepted: 6 March 2018 / Published: 8 March 2018. (This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers) This research used resources of the Advanced Photon Source (APS), a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357. The authors acknowledge all the staff at beamline 5-ID-D DND-CAT of the Advanced Photon Source (APS) at the Argonne National Laboratories, especially Steven Weigand and James Rix for their support before and during the synchrotron experiments. The authors acknowledge Mary Beth Kossuth at Abbott Vascular for providing the preforms. KR and TDL are very thankful to Giuseppe Nenna at ENEA for useful discussions on ray tracing calculations. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 691238, the Jacobs Institute for Molecular Engineering for Medicine at the California Institute of Technology, and the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number F31HL137308. Author Contributions: Karthik Ramachandran and Julia A. Kornfield designed research; Karthik Ramachandran, Riccardo Miscioscia, Giovanni De Filippo, Giuseppe Pandolfi and Tiziana Di Luccio performed research; Karthik Ramachandran, Riccardo Miscioscia, Tiziana Di Luccio and Julia A. Kornfield analyzed data; and Karthik Ramachandran, Riccardo Miscioscia, Tiziana Di Luccio and Julia A. Kornfield wrote the paper. The authors declare no conflict of interest.

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Published - polymers-10-00288.pdf

Supplemental Material - polymers-10-00288-s001.pdf

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Created:
August 21, 2023
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October 18, 2023