Advances of Polymer Stent and Coating

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Networks".

Deadline for manuscript submissions: closed (28 January 2022) | Viewed by 12973

Special Issue Editor


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Guest Editor
Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
Interests: biomedical device design; micro and nano fabrication; nanoimprint; laser machining; flexible sensor; self-expandable stent; biodegradable stent; glucose monitoring system; smartphone-based biomedical system

Special Issue Information

Dear Colleagues,

Polymers continue to evolve, with newer generation of stents aimed at improving clinical outcomes. Drug-eluting stents (DES), which have metal struts and a biodegradable polymer coating, represent the concept of combined mechanical stenosis repair and localized drug delivery. Drug-eluting stents are able to reduce the incidence of in-stent restenosis and the occurrence of neointimal hyperplasia when compared with bare-metal stents (BMS) for the treatment of coronary artery disease. Bioresorbable polymer stents or scaffolds have been developed to overcome the drawbacks of current metallic drug-eluting stents, such as late in-stent restenosis and permanent caging of the vessel. In addition to cardiovascular stents, different types of non-biodegradable and biodegradable polymer stents have been designed for other treatments of the human body, including peripheral vascular occlusive disease, endovascular aneurysm repair, obstructive colorectal cancer, cholangiocarcinoma therapy, esophageal stricture, and urinary tract obstruction.

This Special Issue will focus on the latest research in the design, fabrication, characterization, properties, and functions of polymer stents and polymer coating for stent platform, as well as applications in the design for new treatments. Special attention shall be given to studies of 3D-printed or additive manufactured polymer stents, and their applications. We invite researchers to contribute to this Special Issue with original research papers, short communications, and review articles. 

Prof. Dr. Fuh-Yu Chang
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Polymer stent
  • Drug-eluting coating
  • Bioresorbable stent
  • Biodegradable polymer
  • Cardiovascular stent
  • peripheral vascular stent
  • Biliary stent
  • Colonic stent
  • Esophageal stent
  • Ureteral Stent
  • 3D printing
  • Additive manufacturing
  • Ultrashort pulse laser

Published Papers (4 papers)

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Research

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13 pages, 2002 KiB  
Article
Polymer Coating Integrity, Thrombogenicity and Computational Fluid Dynamics Analysis of Provisional Stenting Technique in the Left Main Bifurcation Setting: Insights from an In-Vitro Model
by Marek Milewski, Chen Koon Jaryl Ng, Pawel Gąsior, Shaoliang Shawn Lian, Su Xiao Qian, Shengjie Lu, Nicolas Foin, Elvin Kedhi, Wojciech Wojakowski and Hui Ying Ang
Polymers 2022, 14(9), 1715; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091715 - 22 Apr 2022
Cited by 2 | Viewed by 1625
Abstract
Currently, the provisional stenting technique is the gold standard in revascularization of lesions located in the left main (LM) bifurcation. The benefit of the routine kissing balloon technique (KBI) in bifurcation lesions is still debated, particularly following the single stent treatment. We compared [...] Read more.
Currently, the provisional stenting technique is the gold standard in revascularization of lesions located in the left main (LM) bifurcation. The benefit of the routine kissing balloon technique (KBI) in bifurcation lesions is still debated, particularly following the single stent treatment. We compared the latest-generation drug-eluting stent (DES) with no side branch (SB) dilatation “keep it open” technique (KIO) vs. KBI technique vs. bifurcation dedicated drug-eluting stent (BD-DES) implantation. In vitro testing was performed under a static condition in bifurcation silicone vessel models. All the devices were implanted in accordance with the manufacturers’ recommendations. As a result, computational fluid dynamics (CFD) analysis demonstrated a statistically higher area of high shear rate in the KIO group when compared to KBI. Likewise, the maximal shear rate was higher in number in the KIO group. Floating strut count based on the OCT imaging was significantly higher in KIO than in KBI and BD-DES. Furthermore, according to OTC analysis, the thrombus area was numerically higher in both KIO and KBI than in the BD-DES. Scanning electron microscopy (SEM) analysis shows the highest degree of strut coating damage in the KBI group. This model demonstrated significant differences in CFD analysis at SB ostia with and without KBI optimization in the LM setting. The adoption of KBI was related to a meaningful reduction of flow disturbances in conventional DES and achieved results similar to BD-DES. Full article
(This article belongs to the Special Issue Advances of Polymer Stent and Coating)
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19 pages, 5705 KiB  
Article
A Complex In Vitro Degradation Study on Polydioxanone Biliary Stents during a Clinically Relevant Period with the Focus on Raman Spectroscopy Validation
by Jan Loskot, Daniel Jezbera, Zuzana Olmrová Zmrhalová, Martina Nalezinková, Dino Alferi, Krisztina Lelkes, Petr Voda, Rudolf Andrýs, Alena Myslivcová Fučíková, Tomáš Hosszú and Aleš Bezrouk
Polymers 2022, 14(5), 938; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14050938 - 26 Feb 2022
Cited by 9 | Viewed by 2373
Abstract
Biodegradable biliary stents are promising treatments for biliary benign stenoses. One of the materials considered for their production is polydioxanone (PPDX), which could exhibit a suitable degradation time for use in biodegradable stents. Proper material degradation characteristics, such as sufficient stiffness and disintegration [...] Read more.
Biodegradable biliary stents are promising treatments for biliary benign stenoses. One of the materials considered for their production is polydioxanone (PPDX), which could exhibit a suitable degradation time for use in biodegradable stents. Proper material degradation characteristics, such as sufficient stiffness and disintegration resistance maintained for a clinically relevant period, are necessary to ensure stent safety and efficacy. The hydrolytic degradation of commercially available polydioxanone biliary stents (ELLA-CS, Hradec Králové, Czech Republic) in phosphate-buffered saline (PBS) was studied. During 9 weeks of degradation, structural, physical, and surface changes were monitored using Raman spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and torsion tests. It was found that the changes in mechanical properties are related to the increase in the ratio of amorphous to crystalline phase, the so-called amorphicity. Monitoring the amorphicity using Raman spectroscopy has proven to be an appropriate method to assess polydioxanone biliary stent degradation. At the 1732 cm−1 Raman peak, the normalized shoulder area is less than 9 cm−1 which indicates stent disintegration. The stent disintegration started after 9 weeks of degradation in PBS, which agrees with previous in vitro studies on polydioxanone materials as well as with in vivo studies on polydioxanone biliary stents. Full article
(This article belongs to the Special Issue Advances of Polymer Stent and Coating)
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Review

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22 pages, 2060 KiB  
Review
Urinary Stent Development and Evaluation Models: In Vitro, Ex Vivo and In Vivo—A European Network of Multidisciplinary Research to Improve Urinary Stents (ENIUS) Initiative
by Noor Buchholz, Alberto Budia, Julia de la Cruz, Wolfgang Kram, Owen Humphreys, Meital Reches, Raquel Valero Boix and Federico Soria
Polymers 2022, 14(9), 1641; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091641 - 19 Apr 2022
Cited by 3 | Viewed by 3220
Abstract
Background: When trying to modify urinary stents, certain pre-clinical steps have to be followed before clinical evaluation in humans. Usually, the process starts as an in silico assessment. The urinary tract is a highly complex, dynamic and variable environment, which makes a [...] Read more.
Background: When trying to modify urinary stents, certain pre-clinical steps have to be followed before clinical evaluation in humans. Usually, the process starts as an in silico assessment. The urinary tract is a highly complex, dynamic and variable environment, which makes a computer simulation closely reflecting physiological conditions extremely challenging. Therefore, the pre-clinical evaluation needs to go through further steps of in vitro, ex vivo and in vivo assessments. Methods and materials: Within the European Network of Multidisciplinary Research to Improve Urinary Stents (ENIUS), the authors summarized and evaluated stent assessment models in silico, in vitro, ex vivo and in vivo. The topic and relevant sub-topics were researched in a systematic literature search in Embase, Scope, Web of Science and PubMed. Clinicaltrials.gov was consulted for ongoing trials. Articles were selected systematically according to guidelines with non-relevant, non-complete, and non-English or Spanish language articles excluded. Results: In the first part of this paper, we critically evaluate in vitro stent assessment models used over the last five decades, outlining briefly their strengths and weaknesses. In the second part, we provide a step-by-step guide on what to consider when setting up an ex vivo model for stent evaluation on the example of a biodegradable stent. Lastly, the third part lists and discusses the pros and cons of available animal models for urinary stent evaluation, this being the final step before human trials. Conclusions: We hope that this overview can provide a practical guide and a critical discussion of the experimental pre-clinical evaluation steps needed, which will help interested readers in choosing the right methodology from the start of a stent evaluation process once an in silico assessment has been completed. Only a transparent multidisciplinary approach using the correct methodology will lead to a successful clinical implementation of any new or modified stent. Full article
(This article belongs to the Special Issue Advances of Polymer Stent and Coating)
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27 pages, 3783 KiB  
Review
Advanced Metallic and Polymeric Coatings for Neural Interfacing: Structures, Properties and Tissue Responses
by Pengfei Yin, Yang Liu, Lin Xiao and Chao Zhang
Polymers 2021, 13(16), 2834; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13162834 - 23 Aug 2021
Cited by 21 | Viewed by 4657
Abstract
Neural electrodes are essential for nerve signal recording, neurostimulation, neuroprosthetics and neuroregeneration, which are critical for the advancement of brain science and the establishment of the next-generation brain–electronic interface, central nerve system therapeutics and artificial intelligence. However, the existing neural electrodes suffer from [...] Read more.
Neural electrodes are essential for nerve signal recording, neurostimulation, neuroprosthetics and neuroregeneration, which are critical for the advancement of brain science and the establishment of the next-generation brain–electronic interface, central nerve system therapeutics and artificial intelligence. However, the existing neural electrodes suffer from drawbacks such as foreign body responses, low sensitivity and limited functionalities. In order to overcome the drawbacks, efforts have been made to create new constructions and configurations of neural electrodes from soft materials, but it is also more practical and economic to improve the functionalities of the existing neural electrodes via surface coatings. In this article, recently reported surface coatings for neural electrodes are carefully categorized and analyzed. The coatings are classified into different categories based on their chemical compositions, i.e., metals, metal oxides, carbons, conducting polymers and hydrogels. The characteristic microstructures, electrochemical properties and fabrication methods of the coatings are comprehensively presented, and their structure–property correlations are discussed. Special focus is given to the biocompatibilities of the coatings, including their foreign-body response, cell affinity, and long-term stability during implantation. This review article can provide useful and sophisticated insights into the functional design, material selection and structural configuration for the next-generation multifunctional coatings of neural electrodes. Full article
(This article belongs to the Special Issue Advances of Polymer Stent and Coating)
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