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Slavkovic V, Palic N, Milenkovic S, Zivic F, Grujovic N. Thermo-Mechanical Characterization of 4D-Printed Biodegradable Shape-Memory Scaffolds Using Four-Axis 3D-Printing System. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5186. [PMID: 37512458 PMCID: PMC10386114 DOI: 10.3390/ma16145186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023]
Abstract
This study was conducted on different models of biodegradable SMP (shape-memory polymer) scaffolds. A comparison was conducted utilizing a basic FDM (fused deposition modeling)/MEX (material extrusion) printer with a standard printing technique and a novel, modified, four-axis printing method with a PLA (poly lactic acid) polymer as the printing material. This way of making the 4D-printed BVS (biodegradable vascular stent) made it possible to achieve high-quality surfaces due to the difference in printing directions and improved mechanical properties-tensile testing showed a doubling in the elongation at break when using the four-axis-printed specimen compared to the regular printing, of 8.15 mm and 3.92 mm, respectfully. Furthermore, the supports created using this method exhibited a significant level of shape recovery following thermomechanical programming. In order to test the shape-memory effect, after the thermomechanical programming, two approaches were applied: one approach was to heat up the specimen after unloading it inside temperature chamber, and the other was to heat it in a warm bath. Both approaches led to an average recovery of the original height of 99.7%, while the in-chamber recovery time was longer (120 s) than the warm-bath recovery (~3 s) due to the more direct specimen heating in the latter case. This shows that 4D printing using the newly proposed four-axis printing is an effective, promising technique that can be used in the future to make biodegradable structures from SMP.
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Affiliation(s)
- Vukasin Slavkovic
- Faculty of Engineering, University of Kragujevac, 34000 Kragujevac, Serbia
| | - Nikola Palic
- Faculty of Engineering, University of Kragujevac, 34000 Kragujevac, Serbia
| | | | - Fatima Zivic
- Faculty of Engineering, University of Kragujevac, 34000 Kragujevac, Serbia
| | - Nenad Grujovic
- Faculty of Engineering, University of Kragujevac, 34000 Kragujevac, Serbia
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InSilc Computational Tool for In Silico Optimization of Drug-Eluting Bioresorbable Vascular Scaffolds. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2022; 2022:5311208. [PMID: 36105243 PMCID: PMC9467806 DOI: 10.1155/2022/5311208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/12/2022] [Accepted: 08/17/2022] [Indexed: 11/17/2022]
Abstract
Stents made by different manufacturers must meet the requirements of standard in vitro mechanical tests performed under different physiological conditions in order to be validated. In addition to in vitro research, there is a need for in silico numerical simulations that can help during the stent prototyping phase. In silico simulations have the ability to give the same stent responses as well as the potential to reduce costs and time needed to carry out experimental tests. The goal of this paper is to show the achievements of the computational platform created as a result of the EU-funded project InSilc, used for numerical testing of most standard tests for validation of preproduction bioresorbable vascular scaffolds (BVSs). Within the platform, an ad hoc simulation protocol has been developed based on the finite element (FE) analysis program PAK and user interface software CAD Field and Solid. Two different designs of two different stents have been numerically simulated using this integrated tool, and the results have been demonstrated. The following standard tests have been performed: longitudinal tensile strength, local compression, kinking, and flex 1-3. Strut thickness and additional pocket holes (slots) in two different scaffolds have been used as representative parameters for comparing the mechanical characteristics of the stents (AB-BVS vs. AB-BVS-thinner and PLLA-prot vs. PLLA-plot-slot). The AB-BVS-thinner prototype shows better overall stress distribution than the AB-BVS, while the PLLA-prot shows better overall stress distribution in comparison to the PLLA-plot-slot. In all cases, the values of the maximum effective stresses are below 220 MPa—the value obtained by in vitro experiment. Despite the presented results, additional considerations should be included before the proposed software can be used as a validation tool for stent prototyping.
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Cheng J, Li J, Deng D, Wu G, Zhou M, Zhao G, Ni Z. Improved mechanical properties of poly(
l
‐lactic acid) stent coated by poly(
d
,
l
‐lactic acid) and poly(
l
‐lactic‐co‐glycolic acid) biopolymer blend. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jie Cheng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Junjie Li
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Dongwen Deng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering Nanjing Forestry University Nanjing China
| | - Min Zhou
- Department of Vascular Surgery The Affiliated Drum Tower Hospital, Nanjing University Medical School Nanjing China
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
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Milosevic M, Anic M, Nikolic D, Geroski V, Milicevic B, Kojic M, Filipovic N. Application of in silico Platform for the Development and Optimization of Fully Bioresorbable Vascular Scaffold Designs. FRONTIERS IN MEDICAL TECHNOLOGY 2021; 3:724062. [PMID: 35047953 PMCID: PMC8757700 DOI: 10.3389/fmedt.2021.724062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/08/2021] [Indexed: 11/29/2022] Open
Abstract
Bioresorbable vascular scaffolds (BVS), made either from polymers or from metals, are promising materials for treating coronary artery disease through the processes of percutaneous transluminal coronary angioplasty. Despite the opinion that bioresorbable polymers are more promising for coronary stents, their long-term advantages over metallic alloys have not yet been demonstrated. The development of new polymer-based BVS or optimization of the existing ones requires engineers to perform many very expensive mechanical tests to identify optimal structural geometry and material characteristics. in silico mechanical testing opens the possibility for a fast and low-cost process of analysis of all the mechanical characteristics and also provides the possibility to compare two or more competing designs. In this study, we used a recently introduced material model of poly-l-lactic acid (PLLA) fully bioresorbable vascular scaffold and recently empowered numerical InSilc platform to perform in silico mechanicals tests of two different stent designs with different material and geometrical characteristics. The result of inflation, radial compression, three-point bending, and two-plate crush tests shows that numerical procedures with true experimental constitutive relationships could provide reliable conclusions and a significant contribution to the optimization and design of bioresorbable polymer-based stents.
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Affiliation(s)
- Miljan Milosevic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Institute for Information Technologies, University of Kragujevac, Kragujevac, Serbia
- Faculty of Information Technologies, Belgrade Metropolitan University, Belgrade, Serbia
| | - Milos Anic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Dalibor Nikolic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Institute for Information Technologies, University of Kragujevac, Kragujevac, Serbia
| | - Vladimir Geroski
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Bogdan Milicevic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Milos Kojic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX, United States
- Serbian Academy of Sciences and Arts, Belgrade, Serbia
| | - Nenad Filipovic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
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