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Wang C, Li T, Guo R, Ji Q, Wang J, Cao Y. [Research on the method of loading exosomes onto absorbable stents]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2024; 38:206-210. [PMID: 38385234 PMCID: PMC10882228 DOI: 10.7507/1002-1892.202310068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Objective To explore a method of loading exosomes onto absorbable stents. Methods By building a stent-(3-aminopropyl) triethoxysilane-1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol) 5000]-exosomes connection, the exosomes were loaded onto absorbable stents to obtained the exosome-eluting absorbable stents. The surface conditions of the stents and absorption of exosomes were observed by scanning electron microscope and identified through the time-of-flight mass spectrometry; the roughness of the stents' surfaces was observed by atomic force microscope; the appearances and sizes of the stents were observed by stereomicroscope; and the radial force was tested by tensile test machine. The absorbable stents were used as control. Results The scanning electron microscope observation showed that the exosome-eluting absorbable stents had some small irregular cracks on the surface where many exosomes could be seen. The atomic force microscopy observation showed that within the range of 5 μm 2, the surface roughness of the absorbable stents was ±20 nm, while the surface roughness of the exosome-eluting absorbable stents was ±70 nm. In the results of time-of-flight mass spectrometry, both the exosome-eluting absorbable stents and exosomes had a peak at the mass charge ratio of 81 (m/z 81), while the absorbable stents did not have this peak. The peak of exosome-eluting absorbable stents at m/z 73 showed a significant decrease compared to the absorbable stents. The stereomicroscope observation showed that the sizes of exosome-eluting absorbable stents met standards and the surfaces had no cracks, burrs, or depressions. The radial force results of the exosome-eluting absorbable stents met the strength standards of the original absorbable stent. Conclusion By applying the chemical connection method, the exosomes successfully loaded onto the absorbable stents. And the sizes and radial forces of this exosome-eluting absorbable stents meet the standards of the original absorbable stents.
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Affiliation(s)
- Chenchen Wang
- Jiamusi University, Jiamusi Heilongjiang, 154007, P. R. China
| | | | | | - Qinghui Ji
- Jiamusi University, Jiamusi Heilongjiang, 154007, P. R. China
| | - Jiangning Wang
- Department of Orthopedics, Shijitan Hospital Affiliated to Capital Medical University, Beijing, 100038, P. R. China
| | - Yulin Cao
- Tangyi Holdings (Shenzhen) Co., Ltd, Shenzhen Guangdong, 518000, P. R. China
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2
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Kantaros A, Ganetsos T. From Static to Dynamic: Smart Materials Pioneering Additive Manufacturing in Regenerative Medicine. Int J Mol Sci 2023; 24:15748. [PMID: 37958733 PMCID: PMC10647622 DOI: 10.3390/ijms242115748] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/26/2023] [Accepted: 10/28/2023] [Indexed: 11/15/2023] Open
Abstract
The emerging field of regenerative medicine holds immense promise for addressing complex tissue and organ regeneration challenges. Central to its advancement is the evolution of additive manufacturing techniques, which have transcended static constructs to embrace dynamic, biomimetic solutions. This manuscript explores the pivotal role of smart materials in this transformative journey, where materials are endowed with dynamic responsiveness to biological cues and environmental changes. By delving into the innovative integration of smart materials, such as shape memory polymers and stimulus-responsive hydrogels, into additive manufacturing processes, this research illuminates the potential to engineer tissue constructs with unparalleled biomimicry. From dynamically adapting scaffolds that mimic the mechanical behavior of native tissues to drug delivery systems that respond to physiological cues, the convergence of smart materials and additive manufacturing heralds a new era in regenerative medicine. This manuscript presents an insightful overview of recent advancements, challenges, and future prospects, underscoring the pivotal role of smart materials as pioneers in shaping the dynamic landscape of regenerative medicine and heralding a future where tissue engineering is propelled beyond static constructs towards biomimetic, responsive, and regenerative solutions.
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Affiliation(s)
- Antreas Kantaros
- Department of Industrial Design and Production Engineering, University of West Attica, 12244 Athens, Greece
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3
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Dezianian S, Azadi M, Razavi SMJ. Topology optimization on metamaterial cells for replacement possibility in non-pneumatic tire and the capability of 3D-printing. PLoS One 2023; 18:e0290345. [PMID: 37831705 PMCID: PMC10575546 DOI: 10.1371/journal.pone.0290345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 08/05/2023] [Indexed: 10/15/2023] Open
Abstract
One of the applications of mechanical metamaterials is in car tires, as a non-pneumatic tire (NPT). Therefore, to find a suitable cell to replace the pneumatic part of the tire, three different solution methods were used, including topology optimization of the cubic unit cell, cylindrical unit cell, and fatigue testing cylindrical sample (FTCS). First, to find the mechanical properties, a tensile test was conducted for materials made of polylactic acid (PLA) and then, the optimization was done based on the weight and overhang control for the possibility of manufacturing with 3D printers, as constraints, besides, the objective of minimum compliance. In the optimization of the cubic unit cell, the sample with a minimum remaining weight of 35% was selected as the optimal sample. However, for the cylindrical unit cell, a sample with a weight limit of 20% was the most optimal state. In contrast, in the FTCS optimization, a specimen with lower remaining weight equal to 60% of the initial weight was selected. After obtaining the answer, five cells in the FTCS and two mentioned cells were evaluated under compressive testing. The samples were also subjected to bending fatigue loadings. The results demonstrated that cellular structures with 15% of lower weight than the optimized samples had the same fatigue lifetime. In the compressive test, the line slope of the specimens with cellular structures in the elastic region of the force-displacement diagram was reduced by 37%, compared to the completely solid samples. However, the weight of these samples decreased by 59%. Furthermore, the fracture surface was also investigated by field-emission scanning electron microscopy. It was observed that a weak connection between the layers was the cause of failure.
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Affiliation(s)
| | - Mohammad Azadi
- Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
| | - Seyed Mohammad Javad Razavi
- Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology, Trondheim, Norway
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Xiang Z, Zhang J, Zhou C, Zhang B, Chen N, Li M, Fu D, Wang Y. Near-Infrared Remotely Controllable Shape Memory Biodegradable Occluder Based on Poly(l-lactide- co-ε-caprolactone)/Gold Nanorod Composite. ACS APPLIED MATERIALS & INTERFACES 2023; 15:42341-42353. [PMID: 37647023 DOI: 10.1021/acsami.3c09852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Biodegradable occluders, which can efficiently eliminate the complications caused by permanent foreign implants, are considered to be the next-generation devices for the interventional treatment of congenital heart disease. However, the controllability of the deployment process of degradable occluders remains a challenge. In this work, a near-infrared (NIR) remotely controllable biodegradable occluder is explored by integrating poly(l-lactide-co-ε-caprolactone) (PLCL) with poly(ethylene glycol)-modified gold nanorods (GNR/PEG). The caprolactone structural units can effectively increase the toughness of poly(l-lactide) and reduce the shape-memory transition temperature of the occluder to a more tissue-friendly temperature. Gold nanorods endow the PLCL-GNR/PEG composite with an excellent photothermal effect. The obtained occluder can be easily loaded into a catheter for transport and spatiotemporally expanded under irradiation with near-infrared light to block the defect site. Both in vitro and in vivo biological experiments showed that PLCL-GNR/PEG composites have good biocompatibility, and the PEGylated gold nanorods could improve the hemocompatibility of the composites to a certain extent by enhancing their hydrophilicity. As a thermoplastic shape-memory polymer, PLCL-GNR/PEG can be easily processed into various forms and structures for different patients and lesions. Therefore, PLCL-GNR/PEG has the potential to be considered as a competitive biodegradable material not only for occluders but also for other biodegradable implants.
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Affiliation(s)
- Zhen Xiang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Jiayi Zhang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Chen Zhou
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Bo Zhang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Nuoya Chen
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Mingyu Li
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Daihua Fu
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China
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5
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Zhang X, Li L, Deng Z. Liquid Metal-Based Flexible Bioelectrodes for Management of In-Stent-Restenosis: Potential Application. BIOSENSORS 2023; 13:795. [PMID: 37622881 PMCID: PMC10452354 DOI: 10.3390/bios13080795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/28/2023] [Accepted: 07/30/2023] [Indexed: 08/26/2023]
Abstract
Although vascular stents have been widely used in clinical practice, there is still a risk of in-stent restenosis after their implantation. Combining conventional vascular stents with liquid metal-based electrodes with impedance detection, irreversible electroporation, and blood pressure detection provides a new direction to completely solve the restenosis problem. Compared with conventional rigid electrodes, liquid metal-based electrodes combine high conductivity and stretchability, and are more compliant with the implantation process of vascular stents and remain in the vasculature for a long period of time. This perspective reviews the types and development of conventional vascular stents and proposes a novel stent that integrates liquid metal-based electrodes on conventional vascular stents. This vascular stent has three major functions of prediction, detection and treatment, and is expected to be a new generation of cardiovascular implant with intelligent sensing and real-time monitoring.
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Affiliation(s)
- Xilong Zhang
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Li
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
- Plastic Surgery Hospital, Chinese Academy of Medical Sciences, Beijing 100144, China
| | - Zhongshan Deng
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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6
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Zhang Y, Ni X, Pan C. Finite element simulation and optimization of mechanical performance of the magnesium-alloy biliary stent. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3592. [PMID: 35293160 DOI: 10.1002/cnm.3592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 01/24/2022] [Accepted: 03/12/2022] [Indexed: 06/14/2023]
Abstract
A biliary stent is used to expand the bile duct during interventional treatment of biliary stricture. To reduce the complications after stent implantation, it is necessary to understand and improve the comprehensive performance of magnesium alloy biliary stents. In this study, at first, the mechanical performance of magnesium alloy biliary stent in bile ducts with different ellipticitiesis studied, and the influence of the ellipticity of bile duct on the interaction of the stent-bile duct coupling system is better understood. Proposed results show the increment of ellipticity of the bile duct will increase the difficulty of expanding the stent. Second, to improve the mechanical performance and degradation performance of the stent simultaneously, an optimal design method based on a zero-order algorithm is used to reduce the maximum equivalent stress on the stent effectively, to make the stress distribution more uniform, and to expand the bile duct of the lesion more effectively and uniformly. The results of this analysis and optimization are useful to predict the clinical effect of stents and to design and optimize stents for both bile duct and other non-vascular.
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Affiliation(s)
- Yanhong Zhang
- School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing, Jiangsu Province, China
| | - Xiaoyu Ni
- School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing, Jiangsu Province, China
| | - Changwang Pan
- Jiangsu Key Laboratory for Design and Manufacture of Micro/Nano Biomedical Instruments Micro-Tech (Nanjing) Co., Ltd, Nanjing, Jiangsu Province, China
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7
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3D Printing of Polymeric Bioresorbable Stents: A Strategy to Improve Both Cellular Compatibility and Mechanical Properties. Polymers (Basel) 2022; 14:polym14061099. [PMID: 35335430 PMCID: PMC8954590 DOI: 10.3390/polym14061099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 12/04/2022] Open
Abstract
One of the leading causes of death is cardiovascular disease, and the most common cardiovascular disease is coronary artery disease. Percutaneous coronary intervention and vascular stents have emerged as a solution to treat coronary artery disease. Nowadays, several types of vascular stents share the same purpose: to reduce the percentage of restenosis, thrombosis, and neointimal hyperplasia and supply mechanical support to the blood vessels. Despite the numerous efforts to create an ideal stent, there is no coronary stent that simultaneously presents the appropriate cellular compatibility and mechanical properties to avoid stent collapse and failure. One of the emerging approaches to solve these problems is improving the mechanical performance of polymeric bioresorbable stents produced through additive manufacturing. Although there have been numerous studies in this field, normalized control parameters for 3D-printed polymeric vascular stents fabrication are absent. The present paper aims to present an overview of the current types of stents and the main polymeric materials used to fabricate the bioresorbable vascular stents. Furthermore, a detailed description of the printing parameters' influence on the mechanical performance and degradation profile of polymeric bioresorbable stents is presented.
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8
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Chen N, Dong X, Ma Y. Evaluation on the Seal Performance of SMP-Based Packers in Oil Wells. Polymers (Basel) 2022; 14:polym14040836. [PMID: 35215747 PMCID: PMC8963099 DOI: 10.3390/polym14040836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/12/2022] [Accepted: 02/18/2022] [Indexed: 02/04/2023] Open
Abstract
Packers based on shape memory polymers (SMPs) are an emerging technology that have the advantages of compact structure, easy manufacture, and adaptability to complex wells. This paper proposes a finite element model to simulate the setting process and mechanical response of an SMP packer. The investigated material is an epoxy-based thermal responsive SMP, whose relaxation modulus and thermal expansion coefficient were measured at different temperatures. Based on the experimental data, the model describes the viscoelastic behavior of the SMP using the generalized Maxwell model. The results show that the SMP packer could provide sufficient contact stress under downhole conditions, even after the stress was relaxed. A further parametric study revealed that the most significant factor in sealing effects is the wellbore pressure, followed by the interference between the packer and the annular, the seal length, the pre-compression, and the setting temperature. High downhole pressures require more significant contact stress and increase the risk of slip between the packer and casing wall by promoting shear stress. Increasing the seal length and interference enhances the contact stress and mitigates the shear stress to improve the seal performance. Pre-compression and setting temperatures are minor factors that have little influence on sealability.
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Affiliation(s)
- Naihan Chen
- Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China;
| | - Xuelin Dong
- Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China;
- Correspondence:
| | - Yinji Ma
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China;
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9
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Characterizing the Mechanical Performance of a Bare-Metal Stent with an Auxetic Cell Geometry. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12020910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This study develops and characterizes the distinctive mechanical features of a stainless-steel metal stent with a tailored structure. A high-precision femtosecond laser was used to micromachine a stent with re-entrant hexagonal (auxetic) cell geometry. We then characterized its mechanical behavior under various mechanical loadings using in vitro experiments and through finite element analysis. The stent properties, such as the higher capability of the stent to bear upon bending, exceptional advantage at elevated levels of twisting angles, and proper buckling, all ensured a preserved opening to maintain the blood flow. The outcomes of this preliminary study present a potential design for a stent with improved physiologically relevant mechanical conditions such as longitudinal contraction, radial strength, and migration of the stent.
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10
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Jiang W, Zhao W, Zhou T, Wang L, Qiu T. A Review on Manufacturing and Post-Processing Technology of Vascular Stents. MICROMACHINES 2022; 13:mi13010140. [PMID: 35056305 PMCID: PMC8778070 DOI: 10.3390/mi13010140] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/13/2022] [Accepted: 01/14/2022] [Indexed: 02/04/2023]
Abstract
Percutaneous coronary intervention (PCI) with stent implantation is one of the most effective treatments for cardiovascular diseases (CVDs). However, there are still many complications after stent implantation. As a medical device with a complex structure and small size, the manufacture and post-processing technology greatly impact the mechanical and medical performances of stents. In this paper, the development history, material, manufacturing method, and post-processing technology of vascular stents are introduced. In particular, this paper focuses on the existing manufacturing technology and post-processing technology of vascular stents and the impact of these technologies on stent performance is described and discussed. Moreover, the future development of vascular stent manufacturing technology will be prospected and proposed.
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Affiliation(s)
- Wei Jiang
- School of Mechanical Engineering, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing 100081, China; (W.J.); (L.W.)
| | - Wenxiang Zhao
- Key Laboratory of Fundamental Science for Advanced Machining, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing 100081, China; (W.Z.); (T.Z.)
| | - Tianfeng Zhou
- Key Laboratory of Fundamental Science for Advanced Machining, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing 100081, China; (W.Z.); (T.Z.)
| | - Liang Wang
- School of Mechanical Engineering, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing 100081, China; (W.J.); (L.W.)
| | - Tianyang Qiu
- Key Laboratory of Fundamental Science for Advanced Machining, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing 100081, China; (W.Z.); (T.Z.)
- Correspondence:
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11
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Tidwell K, Harriet S, Barot V, Bauer A, Vaughan MB, Hossan MR. Design and Analysis of a Biodegradable Polycaprolactone Flow Diverting Stent for Brain Aneurysms. Bioengineering (Basel) 2021; 8:bioengineering8110183. [PMID: 34821749 PMCID: PMC8614946 DOI: 10.3390/bioengineering8110183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/31/2021] [Accepted: 11/09/2021] [Indexed: 11/21/2022] Open
Abstract
The flow diverting stent (FDS) has become a promising endovascular device for the treatment of aneurysms. This research presents a novel biodegradable and non-braided Polycaprolactone (PCL) FDS. The PCL FDS was designed and developed using an in-house fabrication unit and coated on two ends with BaSO4 for angiographic visibility. The mechanical flexibility and quality of FDS surfaces were examined with the UniVert testing machine, scanning electron microscope (SEM), and 3D profilometer. Human umbilical vein endothelial cell (HUVEC) adhesion, proliferation, and cell morphology studies on PCL FDS were performed. The cytotoxicity and NO production by HUVECs with PCL FDS were also conducted. The longitudinal tensile, radial, and bending flexibility were found to be 1.20 ± 0.19 N/mm, 0.56 ± 0.11 N/mm, and 0.34 ± 0.03 N/mm, respectively. The FDS was returned to the original shape and diameter after repeated compression and bending without compromising mechanical integrity. Results also showed that the proliferation and adhesion of HUVECs on the FDS surface increased over time compared to control without FDS. Lactate dehydrogenase (LDH) release and NO production showed that PCL FDS were non-toxic and satisfactory. Cell morphology studies showed that HUVECs were elongated to cover the FD surface and developed an endothelial monolayer. This study is a step forward toward the development and clinical use of biodegradable flow diverting stents for endovascular treatment of the aneurysm.
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Affiliation(s)
- Kaitlyn Tidwell
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Seth Harriet
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Vishal Barot
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Andrew Bauer
- Department of Neurosurgery, University of Oklahoma-Health Science Center, Oklahoma City, OK 73104, USA;
| | - Melville B. Vaughan
- Department of Biology, University of Central Oklahoma, Edmond, OK 73034, USA;
- Center of Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
| | - Mohammad R. Hossan
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
- Center of Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
- Correspondence: ; Tel.: +1-405-975-5295
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12
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Computational Analysis of Mechanical Performance for Composite Polymer Biodegradable Stents. MATERIALS 2021; 14:ma14206016. [PMID: 34683608 PMCID: PMC8539075 DOI: 10.3390/ma14206016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 11/20/2022]
Abstract
Bioresorbable stents (BRS) represent the latest generation of vascular scaffolds used for minimally invasive interventions. They aim to overcome the shortcomings of established bare-metal stents (BMS) and drug-eluting stents (DES). Recent advances in the field of bioprinting offer the possibility of combining biodegradable polymers to produce a composite BRS. Evaluation of the mechanical performance of the novel composite BRS is the focus of this study, based on the idea that they are a promising solution to improve the strength and flexibility performance of single material BRS. Finite element analysis of stent crimping and expansion was performed. Polylactic acid (PLA) and polycaprolactone (PCL) formed a composite stent divided into four layers, resulting in sixteen unique combinations. A comparison of the mechanical performance of the different composite configurations was performed. The resulting stresses, strains, elastic recoil, and foreshortening were evaluated and compared to existing experimental results. Similar behaviour was observed for material configurations that included at least one PLA layer. A pure PCL stent showed significant elastic recoil and less shortening compared to PLA and composite structures. The volumetric ratio of the materials was found to have a more significant effect on recoil and foreshortening than the arrangement of the material layers. Composite BRS offer the possibility of customising the mechanical behaviour of scaffolds. They also have the potential to support the fabrication of personalised or plaque-specific stents.
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13
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Pan C, Han Y, Lu J. Structural Design of Vascular Stents: A Review. MICROMACHINES 2021; 12:mi12070770. [PMID: 34210099 PMCID: PMC8305143 DOI: 10.3390/mi12070770] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/16/2021] [Accepted: 06/24/2021] [Indexed: 11/18/2022]
Abstract
Percutaneous Coronary Intervention (PCI) is currently the most conventional and effective method for clinically treating cardiovascular diseases such as atherosclerosis. Stent implantation, as one of the ways of PCI in the treatment of coronary artery diseases, has become a hot spot in scientific research with more and more patients suffering from cardiovascular diseases. However, vascular stent implanted into vessels of patients often causes complications such as In-Stent Restenosis (ISR). The vascular stent is one of the sophisticated medical devices, a reasonable structure of stent can effectively reduce the complications. In this paper, we introduce the evolution, performance evaluation standards, delivery and deployment, and manufacturing methods of vascular stents. Based on a large number of literature pieces, this paper focuses on designing structures of vascular stents in terms of “bridge (or link)” type, representative volume unit (RVE)/representative unit cell (RUC), and patient-specific stent. Finally, this paper gives an outlook on the future development of designing vascular stents.
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Affiliation(s)
- Chen Pan
- School of Mechanical Engineering, Beijing Institute of Technology, Zhongguancun South Street No. 5, Haidian District, Beijing 100081, China; (C.P.); (J.L.)
- Institute of Engineering Medicine, Beijing Institute of Technology, Zhongguancun South Street No. 5, Haidian District, Beijing 100081, China
| | - Yafeng Han
- School of Mechanical Engineering, Beijing Institute of Technology, Zhongguancun South Street No. 5, Haidian District, Beijing 100081, China; (C.P.); (J.L.)
- Correspondence:
| | - Jiping Lu
- School of Mechanical Engineering, Beijing Institute of Technology, Zhongguancun South Street No. 5, Haidian District, Beijing 100081, China; (C.P.); (J.L.)
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14
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Lee J, Kang SK. Principles for Controlling the Shape Recovery and Degradation Behavior of Biodegradable Shape-Memory Polymers in Biomedical Applications. MICROMACHINES 2021; 12:757. [PMID: 34199036 PMCID: PMC8305960 DOI: 10.3390/mi12070757] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/17/2021] [Accepted: 06/24/2021] [Indexed: 11/16/2022]
Abstract
Polymers with the shape memory effect possess tremendous potential for application in diverse fields, including aerospace, textiles, robotics, and biomedicine, because of their mechanical properties (softness and flexibility) and chemical tunability. Biodegradable shape memory polymers (BSMPs) have unique benefits of long-term biocompatibility and formation of zero-waste byproducts as the final degradable products are resorbed or absorbed via metabolism or enzyme digestion processes. In addition to their application toward the prevention of biofilm formation or internal tissue damage caused by permanent implant materials and the subsequent need for secondary surgery, which causes secondary infections and complications, BSMPs have been highlighted for minimally invasive medical applications. The properties of BSMPs, including high tunability, thermomechanical properties, shape memory performance, and degradation rate, can be achieved by controlling the combination and content of the comonomer and crystallinity. In addition, the biodegradable chemistry and kinetics of BSMPs, which can be controlled by combining several biodegradable polymers with different hydrolysis chemistry products, such as anhydrides, esters, and carbonates, strongly affect the hydrolytic activity and erosion property. A wide range of applications including self-expending stents, wound closure, drug release systems, and tissue repair, suggests that the BSMPs can be applied as actuators on the basis of their shape recovery and degradation ability.
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Affiliation(s)
- Junsang Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea;
| | - Seung-Kyun Kang
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea;
- Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Korea
- Institute of Engineering Research, Seoul National University, Seoul 08826, Korea
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Actuator Behaviour of Tailored Poly(thiourethane) Shape Memory Thermosets. Polymers (Basel) 2021; 13:polym13101571. [PMID: 34068369 PMCID: PMC8153274 DOI: 10.3390/polym13101571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 11/26/2022] Open
Abstract
In this work, a new family of poly(thiourethane) shape memory thermosetting actuators was developed and characterized. These materials can be easily prepared from mixtures of two different aliphatic diisocyanates and a trithiol in the presence of a latent catalyst, allowing an easy manipulation of the formulation. Rheological studies of the curing process confirm the latent character of the formulations. The glass transition temperatures and the mechanical properties can be modified by varying the proportion of diisocyanates (hexamethylene diisocyanate, HDI, and isophorone diisocyanate, IPDI) with stoichiometric amounts of trimethylolpropane tris(3-mercaptopropionate). The shape-memory behavior was deeply investigated under three different conditions: unconstrained, partially constrained, and fully constrained. Tests were performed in single cantilever bending mode to simulate conditions closer to real complex mechanics of thermomechanical actuators under flexural performances. The complex recovery process in single cantilever bending mode was compared with that obtained using tensile mode. The results evidenced that the amount of recovery force in fully constrained conditions, or energy released during the recovery process in partially constrained, can be modulated by simply changing the proportion of both diisocyanates. A simple model based on Timoshenko beam theory was used for the prediction of the amount of work performed. The reported results are an important guideline to design shape-memory materials based on poly(thiourethane) networks, establishing criteria for the choice of the material depending on the expected application.
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Holman H, Kavarana MN, Rajab TK. Smart materials in cardiovascular implants: Shape memory alloys and shape memory polymers. Artif Organs 2020; 45:454-463. [PMID: 33107042 DOI: 10.1111/aor.13851] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/03/2020] [Accepted: 10/19/2020] [Indexed: 12/12/2022]
Abstract
Smart materials have intrinsic properties that change in a controlled fashion in response to external stimuli. Currently, the only smart materials with a significant clinical impact in cardiovascular implant design are shape memory alloys, particularly Nitinol. Recent prodigious progress in material science has resulted in the development of sophisticated shape memory polymers. In this article, we have reviewed the literature and outline the characteristics, advantages, and disadvantages of shape memory alloys and shape memory polymers which are relevant to clinical cardiovascular applications, and describe the potential of these smart materials for applications in coronary stents and transcatheter valves.
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Affiliation(s)
- Heather Holman
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC, USA
| | - Minoo Naozer Kavarana
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC, USA
| | - Taufiek Konrad Rajab
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC, USA
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