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Gao T, McNeill JM, Oliver VA, Xiao L, Mallouk TE. Geometric and Scaling Effects in the Speed of Catalytic Enzyme Micropumps. ACS APPLIED MATERIALS & INTERFACES 2022; 14:39515-39523. [PMID: 35984896 DOI: 10.1021/acsami.2c09555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Self-powered, biocompatible pumps in the nanometer to micron length scale have the potential to enable technology in several fields, including chemical analysis and medical diagnostics. Chemically powered, catalytic micropumps have been developed but are not able to function well in biocompatible environments due to their intolerance of salt solutions and the use of toxic fuels. In contrast, enzymatically powered catalytic pumps offer good biocompatibility, selectivity, and scalability, but their performance at length scales below a few millimeters, which is important to many of their possible applications, has not been well tested. Here, urease-based enzyme pumps of millimeter and micrometer dimensions were fabricated and studied. The scaling of the pumping velocity was measured experimentally and simulated by numerical modeling. Pumping speeds were analyzed accurately by eliminating Brownian noise from the data using enzyme patches between 5 mm and 350 μm in size. Pumping speeds of microns per second could be achieved with urease pumps and were fastest when the channel height exceeded the width of the catalytic pump patch. In all cases, pumping was weak when the dimensions of the patch were 100 μm or less. Experimental and simulation results were consistent with a density-driven pumping mechanism at all sizes studied and served as a framework for the in silico study of more complex two-dimensional (2D) and three-dimensional (3D) geometries. Attempts to create directional flow by juxtaposing inward and outward pumps were unsuccessful because of the symmetry of convection rolls produced by millimeter-size pump patches and the slow speeds of smaller pumps. However, simulations of a corrugated ratchet structure showed that directional pumping could be achieved with pump patches in the millimeter size range.
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Affiliation(s)
- Tianyue Gao
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jeffrey M McNeill
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Vincent A Oliver
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Langqiu Xiao
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Goodin MS, Horvath DJ, Kuban BD, Polakowski AR, Fukamachi K, Flick CR, Karimov JH. Computational Fluid Dynamics Model of Continuous-Flow Total Artificial Heart: Right Pump Impeller Design Changes to Improve Biocompatibility. ASAIO J 2022; 68:829-838. [PMID: 34560715 PMCID: PMC8934311 DOI: 10.1097/mat.0000000000001581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cleveland Clinic is developing a continuous-flow total artificial heart (CFTAH). This novel design operates without valves and is suspended both axially and radially through the balancing of the magnetic and hydrodynamic forces. A series of long-term animal studies with no anticoagulation demonstrated good biocompatibility, without any thromboemboli or infarctions in the organs. However, we observed varying degrees of thrombus attached to the right impeller blades following device explant. No thrombus was found attached to the left impeller blades. The goals for this study were: (1) to use computational fluid dynamics (CFD) to gain insight into the differences in the flow fields surrounding both impellers, and (2) to leverage that knowledge in identifying an improved next-generation right impeller design that could reduce the potential for thrombus formation. Transient CFD simulations of the CFTAH at a blood flow rate and impeller rotational speed mimicking in vivo conditions revealed significant blade tip-induced flow separation and clustered regions of low wall shear stress near the right impeller that were not present for the left impeller. Numerous right impeller design variations were modeled, including changes to the impeller cone angle, number of blades, blade pattern, blade shape, and inlet housing design. The preferred, next-generation right impeller design incorporated a steeper cone angle, a primary/splitter blade design similar to the left impeller, and an increased blade curvature to better align the incoming flow with the impeller blade tips. The next-generation impeller design reduced both the extent of low shear regions near the right impeller surface and flow separation from the blade leading edges, while maintaining the desired hydraulic performance of the original CFTAH design.
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Affiliation(s)
| | | | - Barry D. Kuban
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Anthony R. Polakowski
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Kiyotaka Fukamachi
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
- Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic, Cleveland, OH
| | - Christine R. Flick
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Jamshid H. Karimov
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
- Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic, Cleveland, OH
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On the understanding of dielectric elastomer and its application for all-soft artificial heart. Sci Bull (Beijing) 2021; 66:981-990. [PMID: 36654255 DOI: 10.1016/j.scib.2020.12.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 01/20/2023]
Abstract
Although dielectric elastomer (DE) with substantial actuated strain (AS) has been reported 20 years ago, its scientific understanding remains unclear. The most accepted theory of DE, which is proposed in 2000, holds the view that AS of DE is induced by the Maxwell stress. According to this theory, materials have similar ratios of permittivity and Young's modulus should have similar AS, while the experimental results are on contrary to this theory, and the experimental AS has no relationship with ideal AS. Here, a new dipole-conformation-actuated strain cross-scale model is proposed, which can be generally applied to explain the AS of DE without pre-strain. According to this model, several characteristics of an ideal DE are listed in this work and a new DE based on polyphosphazene (PPZ) is synthesized. The AS of PPZ can reach 84% without any pre-strain. At last, a PPZ-based all soft artificial heart (ASAH) is built, which works in the similar way with natural myocardium, indicating that this material has great application potential and possibility in the construction of an ASAH for heart failure (HF) patients.
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Bui TVA, Hwang JW, Lee JH, Park HJ, Ban K. Challenges and Limitations of Strategies to Promote Therapeutic Potential of Human Mesenchymal Stem Cells for Cell-Based Cardiac Repair. Korean Circ J 2021; 51:97-113. [PMID: 33525065 PMCID: PMC7853896 DOI: 10.4070/kcj.2020.0518] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022] Open
Abstract
Mesenchymal stem cells (MSCs) represent a population of adult stem cells residing in many tissues, mainly bone marrow, adipose tissue, and umbilical cord. Due to the safety and availability of standard procedures and protocols for isolation, culturing, and characterization of these cells, MSCs have emerged as one of the most promising sources for cell-based cardiac regenerative therapy. Once transplanted into a damaged heart, MSCs release paracrine factors that nurture the injured area, prevent further adverse cardiac remodeling, and mediate tissue repair along with vasculature. Numerous preclinical studies applying MSCs have provided significant benefits following myocardial infarction. Despite promising results from preclinical studies using animal models, MSCs are not up to the mark for human clinical trials. As a result, various approaches have been considered to promote the therapeutic potency of MSCs, such as genetic engineering, physical treatments, growth factor, and pharmacological agents. Each strategy has targeted one or multi-potentials of MSCs. In this review, we will describe diverse approaches that have been developed to promote the therapeutic potential of MSCs for cardiac regenerative therapy. Particularly, we will discuss major characteristics of individual strategy to enhance therapeutic efficacy of MSCs including scientific principles, advantages, limitations, and improving factors. This article also will briefly introduce recent novel approaches that MSCs enhanced therapeutic potentials of other cells for cardiac repair.
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Affiliation(s)
- Thi Van Anh Bui
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong SAR, China
| | - Ji Won Hwang
- Department of Biomedicine & Health Sciences, The Catholic University of Korea, Seoul, Korea.,Division of Cardiology, Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea
| | - Jung Hoon Lee
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
| | - Hun Jun Park
- Department of Biomedicine & Health Sciences, The Catholic University of Korea, Seoul, Korea.,Division of Cardiology, Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.,Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea.
| | - Kiwon Ban
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong SAR, China.
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Cordeiro TD, Sousa DL, Cestari IA, Lima AM. A physiological control system for ECG-synchronized pulsatile pediatric ventricular assist devices. Biomed Signal Process Control 2020. [DOI: 10.1016/j.bspc.2019.101752] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sarode DN, Roy S. In Vitro models for thrombogenicity testing of blood-recirculating medical devices. Expert Rev Med Devices 2019; 16:603-616. [PMID: 31154869 DOI: 10.1080/17434440.2019.1627199] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Blood-recirculating medical devices, such as mechanical circulatory support (MCS), extracorporeal membrane oxygenators (ECMO), and hemodialyzers, are commonly used to treat or improve quality of life in patients with cardiac, pulmonary, and renal failure, respectively. As part of their regulatory approval, guidelines for thrombosis evaluation in pre-clinical development have been established. In vitro testing evaluates a device's potential to produce thrombosis markers in static and dynamic flow loops. AREAS COVERED This review focuses on in vitro static and dynamic models to assess thrombosis in blood-recirculating medical devices. A summary of key devices is followed by a review of molecular markers of contact activation. Current thrombosis testing guidance documents, ISO 10993-4, ASTM F-2888, and F-2382 will be discussed, followed by analysis of their application to in vitro testing models. EXPERT OPINION In general, researchers have favored in vivo models to thoroughly evaluate thrombosis, limiting in vitro evaluation to hemolysis. In vitro studies are not standardized and it is often difficult to compare studies on similar devices. As blood-recirculating devices have advanced to include wearable and implantable artificial organs, expanded guidelines standardizing in vitro testing are needed to identify the thrombotic potential without excessive use of in vivo resources during pre-clinical development.
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Affiliation(s)
- Deepika N Sarode
- a Department of Bioengineering and Therapeutic Sciences , University of California , San Francisco , CA , USA
| | - Shuvo Roy
- a Department of Bioengineering and Therapeutic Sciences , University of California , San Francisco , CA , USA
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Kohll AX, Cohrs NH, Walker R, Petrou A, Loepfe M, Schmid Daners M, Falk V, Meboldt M, Stark WJ. Long-Term Performance of a Pneumatically Actuated Soft Pump Manufactured by Rubber Compression Molding. Soft Robot 2019; 6:206-213. [DOI: 10.1089/soro.2018.0057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- A. Xavier Kohll
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Nicholas H. Cohrs
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Roland Walker
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Anastasios Petrou
- Department of Mechanical and Process Engineering, Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - Michael Loepfe
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Marianne Schmid Daners
- Department of Mechanical and Process Engineering, Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - Volkmar Falk
- Department for Cardiothoracic and Vascular Surgery, German Heart Institute Berlin, Berlin, Germany
| | - Mirko Meboldt
- Department of Mechanical and Process Engineering, Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - Wendelin J. Stark
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
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Cohrs NH, Petrou A, Loepfe M, Yliruka M, Schumacher CM, Kohll AX, Starck CT, Schmid Daners M, Meboldt M, Falk V, Stark WJ. A Soft Total Artificial Heart-First Concept Evaluation on a Hybrid Mock Circulation. Artif Organs 2017; 41:948-958. [DOI: 10.1111/aor.12956] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 03/21/2017] [Accepted: 03/27/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Nicholas H. Cohrs
- Institute for Chemical and Bioengineering; ETH Zurich; Zurich Switzerland
| | - Anastasios Petrou
- Product Development Group Zurich, Department of Mechanical and Process Engineering; ETH Zurich; Zurich Switzerland
| | - Michael Loepfe
- Institute for Chemical and Bioengineering; ETH Zurich; Zurich Switzerland
| | - Maria Yliruka
- Institute for Chemical and Bioengineering; ETH Zurich; Zurich Switzerland
| | | | - A. Xavier Kohll
- Institute for Chemical and Bioengineering; ETH Zurich; Zurich Switzerland
| | - Christoph T. Starck
- Department for Cardiothoracic and Vascular Surgery; Deutsches Herzzentrum Berlin; Berlin Germany
| | - Marianne Schmid Daners
- Product Development Group Zurich, Department of Mechanical and Process Engineering; ETH Zurich; Zurich Switzerland
| | - Mirko Meboldt
- Product Development Group Zurich, Department of Mechanical and Process Engineering; ETH Zurich; Zurich Switzerland
| | - Volkmar Falk
- Department for Cardiothoracic and Vascular Surgery; Deutsches Herzzentrum Berlin; Berlin Germany
| | - Wendelin J. Stark
- Institute for Chemical and Bioengineering; ETH Zurich; Zurich Switzerland
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