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Toong DWY, Ng JCK, Cui F, Leo HL, Zhong L, Lian SS, Venkatraman S, Tan LP, Huang YY, Ang HY. Nanoparticles-reinforced poly-l-lactic acid composite materials as bioresorbable scaffold candidates for coronary stents: Insights from mechanical and finite element analysis. J Mech Behav Biomed Mater 2021; 125:104977. [PMID: 34814078 DOI: 10.1016/j.jmbbm.2021.104977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/29/2021] [Accepted: 11/12/2021] [Indexed: 12/22/2022]
Abstract
Current generation of bioresorbable coronary scaffolds (BRS) posed thrombogenicity and deployment issues owing to its thick struts and overall profile. To this end, we hypothesize that the use of nanocomposite materials is able to provide improved material properties and sufficient radial strength for the intended application even at reduced strut thickness. The nanocomposite formulations of tantalum dioxide (Ta2O5), L-lactide functionalized (LA)-Ta2O5, hydroxyapatite (HA) and LA-HA with poly-l-lactic acid (PLLA) were evaluated in this study. Results showed that tensile modulus and strength were enhanced with non-functionalized nanofillers up until 15 wt% loading, whereas ductility was compromised. On the other hand, functionalized nanofillers/PLLA exhibited improved nanofiller dispersion which resulted higher tensile modulus, strength, and ductility. Selected nanocomposite formulations were evaluated using finite element analysis (FEA) of a stent with varying strut thickness (80, 100 and 150 μm). FEA data has shown that nanocomposite BRS with thinner struts (80-100 μm) made with 15 wt% LA-Ta2O5/PLLA and 10 wt% LA-HA/PLLA have increased radial strength, stiffness and reduced recoil compared to PLLA BRS at 150 μm. The reduced strut thickness can potentially mitigate issues such as scaffold thrombosis and promote re-endothelialisation of the vessel.
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Affiliation(s)
- Daniel Wee Yee Toong
- School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore
| | - Jaryl Chen Koon Ng
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore; Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, 117583, Singapore
| | - Fangsen Cui
- Institute of High Performance Computing, A*STAR, 1 Fusionopolis way, 138632, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, 117583, Singapore
| | - Liang Zhong
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore; Duke-NUS Medical School, 8 College Road, 169857, Singapore
| | - Shaoliang Shawn Lian
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, 117583, Singapore
| | - Subbu Venkatraman
- Department of Material Science Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore
| | - Lay Poh Tan
- School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore
| | - Ying Ying Huang
- School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore.
| | - Hui Ying Ang
- National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore; Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, 117583, Singapore; Duke-NUS Medical School, 8 College Road, 169857, Singapore.
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Zheng K, Yuan S, Hahn H, Branicio PS. Excess free volume and structural properties of inert gas condensation synthesized nanoparticles based CuZr nanoglasses. Sci Rep 2021; 11:19246. [PMID: 34584145 PMCID: PMC8478923 DOI: 10.1038/s41598-021-98494-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/31/2021] [Indexed: 11/09/2022] Open
Abstract
Nanoglass (NG) as a new structure-tunable material has been investigated using both experiments and computational modeling. Experimentally, inert gas condensation (IGC) is commonly employed to prepare metallic glass (MG) nanoparticles that are consolidated using cold compression to generate an NG. In computational modeling, various methods have been used to generate NGs. However, due to the high computational cost involved, heretofore modeling investigations have not followed the experimental synthesis route. In this work, we use molecular dynamics simulations to generate an NG model by consolidating IGC-prepared Cu64Zr36 nanoparticles following a workflow similar to that of experiments. The resulting structure is compared with those of NGs produced following two alternative procedures previously used: direct generation employing Voronoi tessellation and consolidation of spherical nanoparticles carved from an MG sample. We focus on the characterization of the excess free volume and the Voronoi polyhedral statistics in order to identify and quantify contrasting features of the glass-glass interfaces in the three NG samples prepared using distinct methods. Results indicate that glass-glass interfaces in IGC-based NGs are thicker and display higher structural contrast with their parent MG structure. Nanoparticle-based methods display excess free volume exceeding 4%, in agreement with experiments. IGC-prepared nanoparticles, which display Cu segregation to their surfaces, generate the highest glass-glass interface excess free volume levels and the largest relative interface volume with excess free volume higher than 3%. Voronoi polyhedral analysis indicates a sharp drop in the full icosahedral motif fraction in the glass-glass interfaces in nanoparticle-based NG as compared to their parent MG.
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Affiliation(s)
- Kaifeng Zheng
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 3651 Watt Way, Los Angeles, CA, 90089, USA
| | - Suyue Yuan
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 3651 Watt Way, Los Angeles, CA, 90089, USA
| | - Horst Hahn
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Paulo S Branicio
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 3651 Watt Way, Los Angeles, CA, 90089, USA.
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Abstract
The synthesis of nanomaterials, with characteristic dimensions of 1 to 100 nm, is a key component of nanotechnology. Vapor-phase synthesis of nanomaterials has numerous advantages such as high product purity, high-throughput continuous operation, and scalability that have made it the dominant approach for the commercial synthesis of nanomaterials. At the same time, this class of methods has great potential for expanded use in research and development. Here, we present a broad review of progress in vapor-phase nanomaterial synthesis. We describe physically-based vapor-phase synthesis methods including inert gas condensation, spark discharge generation, and pulsed laser ablation; plasma processing methods including thermal- and non-thermal plasma processing; and chemically-based vapor-phase synthesis methods including chemical vapor condensation, flame-based aerosol synthesis, spray pyrolysis, and laser pyrolysis. In addition, we summarize the nanomaterials produced by each method, along with representative applications, and describe the synthesis of the most important materials produced by each method in greater detail.
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Affiliation(s)
- Mohammad Malekzadeh
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Mark T Swihart
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA. and RENEW Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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