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Goldsmith R, Tsan YC, Scissors R, Helms A, Brody M. In Vitro Assessment of Cardiac Fibroblast Activation at Physiologic Stiffness. Curr Protoc 2024; 4:e1025. [PMID: 38600839 PMCID: PMC11013569 DOI: 10.1002/cpz1.1025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Cardiac fibroblasts (CF) are an essential cell type in cardiac physiology, playing diverse roles in maintaining structural integrity, extracellular matrix (ECM) synthesis, and tissue repair. Under normal conditions, these cells reside in the interstitium in a quiescent state poised to sense and respond to injury by synthesizing and secreting collagen, vimentin, hyaluronan, and other ECM components. In response to mechanical and chemical stimuli, these "resident" fibroblasts can undergo a transformation through a continuum of activation states into what is commonly known as a "myofibroblast," in a process critical for injury response. Despite progress in understanding the contribution of fibroblasts to cardiac health and disease, much remains unknown about the signaling mediating this activation, in part owing to technical challenges in evaluating CF function and activation status in vitro. Given their role in monitoring the ECM, CFs are acutely sensitive to stiffness and pressure. High basal activation of isolated CFs is common due to the super-physiologic stiffness of traditional cell culture substrates, making assays dependent on quiescent cells challenging. To overcome this problem, cell culture parameters must be tightly controlled, and the use of dishes coated with biocompatible reduced-stiffness substrates, such as 8-kPa polydimethylsiloxane (PDMS), has shown promise in reducing basal activation of fibroblasts. Here, we describe cell culture protocol for maintaining CF quiescence in vitro to enable a dynamic range for the assessment of activation status in response to fibrogenic stimuli using PDMS-coated coverslips. Our protocol provides a cost-effective tool to study fibroblast signaling and activity, allowing researchers to better understand the underlying mechanisms involved in cardiac fibrosis. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Generation of 8-kPa polydimethylsiloxane (PDMS)/gelatin-coated coverslips for cardiac fibroblast cell culture Basic Protocol 2: Isolation of adult cardiac fibroblasts and plating onto PDMS coverslips Basic Protocol 3: Assessment of cardiac fibroblast activation by α smooth muscle actin (αSMA) immunocytochemistry.
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Affiliation(s)
- R.S. Goldsmith
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, United States
| | - Y-C Tsan
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States
| | - R.E. Scissors
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, United States
| | - A.S. Helms
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States
| | - M.J. Brody
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, United States
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States
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Hawkes W, Marhuenda E, Reynolds P, O'Neill C, Pandey P, Samuel Wilson DG, Freeley M, Huang D, Hu J, Gondarenko S, Hone J, Gadegaard N, Palma M, Iskratsch T. Regulation of cardiomyocyte adhesion and mechanosignalling through distinct nanoscale behaviour of integrin ligands mimicking healthy or fibrotic extracellular matrix. Philos Trans R Soc Lond B Biol Sci 2022; 377:20220021. [PMID: 36189804 PMCID: PMC9527911 DOI: 10.1098/rstb.2022.0021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 04/12/2022] [Indexed: 12/21/2022] Open
Abstract
The stiffness of the cardiovascular environment changes during ageing and in disease and contributes to disease incidence and progression. Changing collagen expression and cross-linking regulate the rigidity of the cardiac extracellular matrix (ECM). Additionally, basal lamina glycoproteins, especially laminin and fibronectin regulate cardiomyocyte adhesion formation, mechanics and mechanosignalling. Laminin is abundant in the healthy heart, but fibronectin is increasingly expressed in the fibrotic heart. ECM receptors are co-regulated with the changing ECM. Owing to differences in integrin dynamics, clustering and downstream adhesion formation this is expected to ultimately influence cardiomyocyte mechanosignalling; however, details remain elusive. Here, we sought to investigate how different cardiomyocyte integrin/ligand combinations affect adhesion formation, traction forces and mechanosignalling, using a combination of uniformly coated surfaces with defined stiffness, polydimethylsiloxane nanopillars, micropatterning and specifically designed bionanoarrays for precise ligand presentation. Thereby we found that the adhesion nanoscale organization, signalling and traction force generation of neonatal rat cardiomyocytes (which express both laminin and fibronectin binding integrins) are strongly dependent on the integrin/ligand combination. Together our data indicate that the presence of fibronectin in combination with the enhanced stiffness in fibrotic areas will strongly impact on the cardiomyocyte behaviour and influence disease progression. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- William Hawkes
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
- Department of Chemistry, Queen Mary University of London, London E1 4NS, UK
| | - Emilie Marhuenda
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Paul Reynolds
- School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
| | - Caoimhe O'Neill
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Pragati Pandey
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | | | - Mark Freeley
- Department of Chemistry, Queen Mary University of London, London E1 4NS, UK
| | - Da Huang
- Department of Chemistry, Queen Mary University of London, London E1 4NS, UK
| | - Junquiang Hu
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - Sasha Gondarenko
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | | | - Matteo Palma
- Department of Chemistry, Queen Mary University of London, London E1 4NS, UK
| | - Thomas Iskratsch
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
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Balseiro-Romero M, Prieto-Fernández Á, Shor LM, Ghoshal S, Baveye PC, Ortega-Calvo JJ. Chemotactic Bacteria Facilitate the Dispersion of Nonmotile Bacteria through Micrometer-Sized Pores in Engineered Porous Media. Environ Sci Technol 2022; 56:13975-13984. [PMID: 36103595 PMCID: PMC9535858 DOI: 10.1021/acs.est.2c03149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/09/2022] [Accepted: 08/20/2022] [Indexed: 06/15/2023]
Abstract
Recent research has demonstrated that chemotactic bacteria can disperse inside microsized pores while traveling toward favorable conditions. Microbe-microbe cotransport might enable nonmotile bacteria to be carried with motile partners to enhance their dispersion and reduce their deposition in porous systems. The aim of this study was to demonstrate the enhancement in the dispersion of nonmotile bacteria (Mycobacterium gilvum VM552, a polycyclic aromatic hydrocarbon-degrader, and Sphingobium sp. D4, a hexachlorocyclohexane-degrader, through micrometer-sized pores near the exclusion-cell-size limit, in the presence of motile Pseudomonas putida G7 cells. For this purpose, we used bioreactors equipped with two chambers that were separated with membrane filters with 3, 5, and 12 μm pore sizes and capillary polydimethylsiloxane (PDMS) microarrays (20 μm × 35 μm × 2.2 mm). The cotransport of nonmotile bacteria occurred exclusively in the presence of a chemoattractant concentration gradient, and therefore, a directed flow of motile cells. This cotransport was more intense in the presence of larger pores (12 μm) and strong chemoeffectors (γ-aminobutyric acid). The mechanism that governed cotransport at the cell scale involved mechanical pushing and hydrodynamic interactions. Chemotaxis-mediated cotransport of bacterial degraders and its implications in pore accessibility opens new avenues for the enhancement of bacterial dispersion in porous media and the biodegradation of heterogeneously contaminated scenarios.
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Affiliation(s)
- María Balseiro-Romero
- Instituto
de Recursos Naturales y Agrobiología de Sevilla (IRNAS), Consejo Superior de Investigaciones Científicas
(CSIC), Avda. Reina Mercedes 10, 41012 Sevilla, Spain
| | - Ángeles Prieto-Fernández
- Instituto
de Investigaciones Agrobiológicas de Galicia (IIAG), Consejo Superior de Investigaciones Científicas
(CSIC), Avda. de Vigo s/n, 15705 Santiago de Compostela, Spain
| | - Leslie M. Shor
- Department
of Chemical and Biomolecular Engineering, University of Connecticut, Castleman Building Rm. 224, Connecticut 06269-3237 Storrs, United States
| | - Subhasis Ghoshal
- Department
of Civil Engineering, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | | | - José Julio Ortega-Calvo
- Instituto
de Recursos Naturales y Agrobiología de Sevilla (IRNAS), Consejo Superior de Investigaciones Científicas
(CSIC), Avda. Reina Mercedes 10, 41012 Sevilla, Spain
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4
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Shen Y, Jing D, Zhao Z. The effect of AKT in extracellular matrix stiffness induced osteogenic differentiation of hBMSCs. Cell Signal 2022; 99:110404. [PMID: 35835331 DOI: 10.1016/j.cellsig.2022.110404] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 07/02/2022] [Accepted: 07/08/2022] [Indexed: 02/05/2023]
Abstract
Extracellular matrix (ECM) stiffness is an important biophysical factor in human bone marrow mesenchymal stem cells (hBMSCs) differentiation. Although there is evidence that Yes-associated protein (YAP) plays an important role in ECM elasticity induced osteogenesis, but the regulatory mechanism and signaling pathways have not been distinctly uncovered. In this study, hBMSCs were cultured on collagen-coated polydimethylsiloxane hydrogels with stiffness corresponding to Young's moduli of 0.5 kPa and 32 kPa, and gene chip analyses revealed the phosphoinositide 3-kinase (PI3K)-AKT pathway was highly correlated with ECM stiffness. Following western blots indicated that AKT phosphorylation was evidently affected in 5th-7th days after ECM stiffness stimulation, while PI3K showed little difference. The AKT activator SC79 and inhibitor MK2206 were utilized to modulate AKT phosphorylation. SC79 and MK2206 caused alteration in the mRNA expression and protein level of alkaline phosphatase (ALP), collagen type I alpha 1 (COL1A1) and runt related transcription factor 2 (RUNX2). On 32 kPa substrates, YAP enrichment in nucleus were significantly promoted by SC79 and remarkably decreased by MK2206. Besides, the ratio of YAP/p-YAP is upregulated by SC79 on both 32 kPa and 0.5 kPa substrates. In conclusion, these findings suggest that AKT is involved in the modulation of ECM stiffness induced osteogenesis, and AKT phosphorylation also influences the subcellular localization and activation of YAP.
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Affiliation(s)
- Yu Shen
- School of Basic Medical Sciences, Chengdu University, Chengdu 610106, China
| | - Dian Jing
- Department of Orthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, China.
| | - Zhihe Zhao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
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Guo Y, Merten AL, Schöler U, Yu ZY, Cvetkovska J, Fatkin D, Feneley MP, Martinac B, Friedrich O. In vitro cell stretching technology (IsoStretcher) as an approach to unravel Piezo1-mediated cardiac mechanotransduction. Prog Biophys Mol Biol 2021; 159:22-33. [PMID: 32763257 DOI: 10.1016/j.pbiomolbio.2020.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/09/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022]
Abstract
The transformation of electrical signals into mechanical action of the heart underlying blood circulation results in mechanical stimuli during active contraction or passive filling distention, which conversely modulate electrical signals. This feedback mechanism is known as cardiac mechano-electric coupling (MEC). The cardiac MEC involves complex activation of mechanical biosensors initiating short-term and long-term effects through Ca2+ signals in cardiomyocytes in acute and chronic pressure overload scenarios (e.g. cardiac hypertrophy). Although it is largely still unknown how mechanical forces alter cardiac function at the molecular level, mechanosensitive channels, including the recently discovered family of Piezo channels, have been thought to play a major role in the cardiac MEC and are also suspected to contribute to development of cardiac hypertrophy and heart failure. The earliest reports of mechanosensitive channel activity recognized that their gating could be controlled by membrane stretch. In this article, we provide an overview of the stretch devices, which have been employed for studies of the effects of mechanical stimuli on muscle and heart cells. We also describe novel experiments examining the activity of Piezo1 channels under multiaxial stretch applied using polydimethylsiloxane (PDMS) stretch chambers and IsoStretcher technology to achieve isotropic stretching stimulation to cultured HL-1 cardiac muscle cells which express an appreciable amount of Piezo1.
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Affiliation(s)
- Yang Guo
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Cardiac Physiology and Transplantation Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia
| | - Anna-Lena Merten
- Institute of Medical Biotechnology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; School in Advanced Optical Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; Muscle Research Center Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Ulrike Schöler
- Institute of Medical Biotechnology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; School in Advanced Optical Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; Muscle Research Center Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Ze-Yan Yu
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Cardiac Physiology and Transplantation Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia
| | - Jasmina Cvetkovska
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Diane Fatkin
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia; Department of Cardiology, St Vincent's Hospital, Darlinghurst, NSW, Australia
| | - Michael P Feneley
- Cardiac Physiology and Transplantation Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia; Department of Cardiology, St Vincent's Hospital, Darlinghurst, NSW, Australia
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia.
| | - Oliver Friedrich
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Institute of Medical Biotechnology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; School in Advanced Optical Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; Muscle Research Center Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
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6
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Liu D, Yin J, Liang S, Shi W, Jiang X, Gao Y. Enzyme-Regulated Peptide-Liquid Metal Hybrid Hydrogels as Cell Amber for Single-Cell Manipulation. ACS Appl Mater Interfaces 2020; 12:45807-45813. [PMID: 32951417 DOI: 10.1021/acsami.0c13334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Current strategies to construct cell-based bioartificial tissues largely remain on a multicell level. Taking cell diversity into account, single-cell manipulation is urgently needed for delicate bioartificial tissue construction. Current single-cell isolation and profiling techniques involve invasive processes and thus are not applicable for single-cell manipulation. Here, we managed to fabricate peptide-liquid metal hybrid hydrogels as "cell ambers" which were suitable for single-cell isolation as well as further handling. The successful preparation of uniform liquid metal nanoparticles allowed the fabrication of peptide-liquid metal hydrogel with excellent recovery property upon mechanical destruction. The alkaline phosphatase-instructed supramolecular self-assembly process allowed the formation of microhydrogel post-filling in the PDMS template. The co-culture of the hydrogel precursor and mammalian cells realized the embedding of cells into elastic hydrogels which were the so-called cell ambers. The cell ambers turned out to be biocompatible and capable of supporting cell survival. Aided with the micro-operating system and a laser scanning confocal microscope, we could arrange these as-prepared 3D single-cell ambers into various patterns as desired. Our strategy provided the possibility to manipulate a single cell, which served as a prototype of cell architecture toward cell-based bioartificial tissue construction.
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Affiliation(s)
- Dongdong Liu
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiaxiang Yin
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Sen Liang
- The Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences, Beijing 100190, China
| | - Wensheng Shi
- The Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences, Beijing 100190, China
| | - Xingyu Jiang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
- Department of Biomedical Engineering, Southern University of Science & Technology, Shenzhen, Guangdong 518055, China
| | - Yuan Gao
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
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7
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Dinh Le TS, An J, Huang Y, Vo Q, Boonruangkan J, Tran T, Kim SW, Sun G, Kim YJ. Ultrasensitive Anti-Interference Voice Recognition by Bio-Inspired Skin-Attachable Self-Cleaning Acoustic Sensors. ACS Nano 2019; 13:13293-13303. [PMID: 31687810 DOI: 10.1021/acsnano.9b06354] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Human voice recognition systems (VRSs) are a prerequisite for voice-controlled human-machine interfaces (HMIs). In order to avoid interference from unexpected background noises, skin-attachable VRSs are proposed to directly detect physiological mechanoacoustic signals based on the vibrations of vocal cords. However, the sensitivity and response time of existing VRSs are bottlenecks for efficient HMIs. In addition, water-based contaminants in our daily lives, such as skin moisture and raindrops, normally result in performance degradation or even functional failure of VRSs. Herein, we present a skin-attachable self-cleaning ultrasensitive and ultrafast acoustic sensor based on a reduced graphene oxide/polydimethylsiloxane composite film with bioinspired microcracks and hierarchical surface textures. Benefitting from the synergetic effect of the spider-slit-organ-like multiscale jagged microcracks and the lotus-leaf-like hierarchical structures, our superhydrophobic VRS exhibits an ultrahigh sensitivity (gauge factor, GF = 8699), an ultralow detection limit (ε = 0.000 064%), an ultrafast response/recovery behavior, an excellent device durability (>10 000 cycles), and reliable detection of acoustic vibrations over the audible frequency range (20-20 000 Hz) with high signal-to-noise ratios. These superb performances endow our skin-attachable VRS with anti-interference perception of human voices with high precision even in noisy environments, which will expedite the voice-controlled HMIs.
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Affiliation(s)
- Truong-Son Dinh Le
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Jianing An
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Yi Huang
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Quoc Vo
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Jeeranan Boonruangkan
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Tuan Tran
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
| | - Seung-Woo Kim
- Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Science Town, Daejeon 34141 , South Korea
| | - Gengzhi Sun
- Institute of Advanced Materials (IAM) , Nanjing Tech University (NanjingTech) , 30 South Puzhu Road , Nanjing 211816 , People's Republic of China
- Institute of Flexible Electronics (IFE) , Northwestern Polytechnical University , 127 West Youyi Road , Xi'an 710072 , People's Republic of China
| | - Young-Jin Kim
- School of Mechanical and Aerospace Engineering , Nanyang Technological University (NTU) , 50 Nanyang Avenue , Singapore 639798 , Singapore
- Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Science Town, Daejeon 34141 , South Korea
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Abstract
Liquefaction and solidification of materials are the most fundamental changes observed during thermal phase transitions, yet the design of organic and polymeric soft materials showing isothermal reversible liquid-nonliquid conversion remains challenging. Here, we demonstrate that solvent-free repeatable molecular architectural transformation between liquid-star and nonliquid-network polymers that relies on cleavage and reformation of a covalent bond in hexaarylbiimidazole. Liquid four-armed star-shaped poly(n-butyl acrylate) and poly(dimethyl siloxane) with 2,4,5-triphenylimidazole end groups were first synthesized. Subsequent oxidation of the 2,4,5-triphenylimidazoles into 2,4,5-triphenylimidazoryl radicals and their coupling with these liquid star polymers to form hexaarylbiimidazoles afforded the corresponding nonliquid network polymers. The resulting nonliquid network polymers liquefied upon UV irradiation and produced liquid star-shaped polymers with 2,4,5-triphenylimidazoryl radical end groups that reverted to nonliquid network polymers again by recoupling of the generated 2,4,5-triphenylimidazoryl radicals immediately after terminating UV irradiation.The design of organic and polymeric soft materials showing isothermal reversible liquid-nonliquid conversion is challenging. Here, the authors show solvent-free repeatable molecular architectural transformation between liquid-star and non-liquid-network polymers by the cleavage and reformation of covalent bonds in the polymer chain.
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Affiliation(s)
- Satoshi Honda
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
| | - Taro Toyota
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
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9
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Abstract
Bacterial biofilms are highly tolerant to antimicrobials and play an important role in the development and spread of antibiotic resistance based on horizontal gene transfer due to close cell-to-cell contact. As an important surface property, topography has been shown to affect bacterial adhesion and biofilm formation. Here, we demonstrate that micrometer-scale surface topographies also affect horizontal gene transfer through conjugation in bacterial biofilms. Specifically, biofilm formation and associated conjugation on poly(dimethylsiloxane) (PDMS) surfaces with 10 μm tall protruding patterns were studied using fluorescently labeled donor and recipient strains of Escherichia coli. The results demonstrate that square-shaped topographic patterns with side length of 20, 50, and 100 μm and interpattern distance equal to or larger than 10 μm promote biofilm formation and conjugation compared to the smooth control. The vertical sides of these topographic features were found to be the "hot spots" for bacterial conjugation compared to the top of patterns and grooves between topographic features. The increase in conjugation frequency on the sides of topographic patterns was attributed to the high cell density of recipient cells at these locations. A motility (motB) mutant of the recipient strain exhibited defects in biofilm formation at the "hot spots" and conjugation, which were recovered by complementing the motB gene on a plasmid. These results also provided guidance for designing surface topographies that can reduce conjugation. Specifically, 10 μm tall hexagon-shaped topographic patterns with side length of 15 μm and interpattern distance of 2 μm were prepared to reduce biofilm formation on the side of protruding patterns and interrupt cell-cell interaction in the grooves. This topography exhibited 85% and 46% reduction of biofilm formation and associated conjugation, respectively, compared to the smooth control.
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Affiliation(s)
- Huan Gu
- Department of Biomedical and Chemical Engineering, ‡Syracuse Biomaterials Institute, §Department of Civil and Environmental Engineering, and ∥Department of Biology, Syracuse University , Syracuse, New York 13244, United States
| | - Kristopher W Kolewe
- Department of Biomedical and Chemical Engineering, ‡Syracuse Biomaterials Institute, §Department of Civil and Environmental Engineering, and ∥Department of Biology, Syracuse University , Syracuse, New York 13244, United States
| | - Dacheng Ren
- Department of Biomedical and Chemical Engineering, ‡Syracuse Biomaterials Institute, §Department of Civil and Environmental Engineering, and ∥Department of Biology, Syracuse University , Syracuse, New York 13244, United States
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10
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Jullok N, Martínez R, Wouters C, Luis P, Sanz MT, Van der Bruggen B. A biologically inspired hydrophobic membrane for application in pervaporation. Langmuir 2013; 29:1510-1516. [PMID: 23323794 DOI: 10.1021/la3050253] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
An artificial polydimethylsiloxane/polyphenylsulfone (PDMS/PPSU) membrane, which emulates the hydrophobic behavior of natural membranes, was synthesized. Hydrophobicity was achieved by coating the membrane surface sublayer using conventional silicon material, which imitates the character of epicuticular wax (EW) of Prunus laurocerasus L. leaves. It was then applied as a separation medium in pervaporation (PV) of diluted mixtures of ethyl acetate and aroma compounds. The membrane's biomimetic characteristics were evaluated using surface morphology analyses, that is, Fourier transform infrared (FTIR), water contact angle measurements, and SEM imaging. A comparison of properties of the membranes synthesized in this work against selected hydrophobic plant leaves indicated a good agreement. PV using these biologically inspired artificial membranes demonstrated preference for the permeation of ethyl acetate. Besides intrinsic characteristics, it was also observed that the chemical potential is highly influential in activating sorption, diffusion, and desorption of a specific compound.
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Affiliation(s)
- Nora Jullok
- Department of Chemical Engineering, Process Engineering for Sustainable Systems (ProcESS), KU Leuven, W. de Croylaan 46, B-3001 Heverlee, Belgium.
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Abstract
UNLABELLED Trimethylamine (TMA) found in some leafy vegetables, such as spinach, cabbage, and lettuce, at alkaline pH was identified and quantified using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME and GC-MS). HS-SPME conditions were optimized at an adsorption temperature of 50 °C, equilibration time of 5 min, and adsorption time of 5 min with 65 μm of polydimethylsiloxane/divinylbenzene fiber. The TMA that was formed from spinach, cabbage, and lettuce was assayed at pH 7 to 11 for 0 to 4 h at 50 °C using HS-SPME. The results showed that the amount of TMA formed was dependent on pH. The amount of TMA formed increased dramatically at a pH greater than 9. TMA was not formed at a pH lower than 7. Spinach produced a higher amount of TMA than cabbage or lettuce. TMA was formed at alkaline pH from choline, betaine, and carnitine, which are TMA precursors. To confirm the SPME results, TMA was quantitated using the AOAC official method. Data obtained from chemical analysis were in good agreement with the SPME data. The formation mechanism of TMA is thought to be the Hofmann elimination reaction, which generates amine compounds at alkaline pH. PRACTICAL APPLICATION Fishy off-flavor in foods is associated with trimethylamine (TMA), which is frequently found in fish and seafood. In this study, TMA was identified for the first time in some leafy vegetables, such as spinach, cabbage, and lettuce, at alkaline pH. The presence of TMA in leafy vegetables under certain circumstances such as high pH and temperature may affect the sensory properties of foods containing these vegetables.
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Affiliation(s)
- Jae-Ean Shim
- Department of Food Engineering, Dankook University, Dongnam-gu, Cheonan, Korea
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12
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Wang Y, Lee D, Zhang L, Jeon H, Mendoza-Elias JE, Harvat TA, Hassan SZ, Zhou A, Eddington DT, Oberholzer J. Systematic prevention of bubble formation and accumulation for long-term culture of pancreatic islet cells in microfluidic device. Biomed Microdevices 2012; 14:419-26. [PMID: 22252566 PMCID: PMC3303988 DOI: 10.1007/s10544-011-9618-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Reliable long-term cell culture in microfluidic system is limited by air bubble formation and accumulation. In this study, we developed a bubble removal system capable of both trapping and discharging air bubbles in a consistent and reliable manner. Combined with PDMS (Polydimethylsiloxane) hydrophilic surface treatment and vacuum filling, a microfluidic perifusion system equipped with the bubble trap was successfully applied for long-term culture of mouse pancreatic islets with no bubble formation and no flow interruption. In addition to demonstrating normal cell viability and islet morphology, post-cultured islets exhibited normal insulin secretion kinetics, intracellular calcium signaling, and changes in mitochondrial potentials in response to glucose challenge. This design could be easily adapted by other microfluidic systems due to its simple design, ease of fabrication, and portability.
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Affiliation(s)
- Yong Wang
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
| | - Dongyoung Lee
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
- Department of Bioengineering, University of Illinois at Chicago, IL, USA
| | - Lisa Zhang
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
| | - Hyojin Jeon
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
| | - Joshua E. Mendoza-Elias
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
- Department of Bioengineering, University of Illinois at Chicago, IL, USA
| | - Tricia A. Harvat
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
| | - Sarah Z. Hassan
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
| | - Amanda Zhou
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
| | - David T. Eddington
- Department of Bioengineering, University of Illinois at Chicago, IL, USA
| | - José Oberholzer
- Department of Transplant/Surgery, University of Illinois at Chicago, IL, USA
- Department of Bioengineering, University of Illinois at Chicago, IL, USA
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13
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Grossmann G, Guo WJ, Ehrhardt DW, Frommer WB, Sit RV, Quake SR, Meier M. The RootChip: an integrated microfluidic chip for plant science. Plant Cell 2011; 23:4234-40. [PMID: 22186371 PMCID: PMC3269862 DOI: 10.1105/tpc.111.092577] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/17/2011] [Accepted: 12/03/2011] [Indexed: 05/18/2023]
Abstract
Studying development and physiology of growing roots is challenging due to limitations regarding cellular and subcellular analysis under controlled environmental conditions. We describe a microfluidic chip platform, called RootChip, that integrates live-cell imaging of growth and metabolism of Arabidopsis thaliana roots with rapid modulation of environmental conditions. The RootChip has separate chambers for individual regulation of the microenvironment of multiple roots from multiple seedlings in parallel. We demonstrate the utility of The RootChip by monitoring time-resolved growth and cytosolic sugar levels at subcellular resolution in plants by a genetically encoded fluorescence sensor for glucose and galactose. The RootChip can be modified for use with roots from other plant species by adapting the chamber geometry and facilitates the systematic analysis of root growth and metabolism from multiple seedlings, paving the way for large-scale phenotyping of root metabolism and signaling.
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Affiliation(s)
- Guido Grossmann
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Woei-Jiun Guo
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - David W. Ehrhardt
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Wolf B. Frommer
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Rene V. Sit
- Howard Hughes Medical Institute, Stanford, California 94605
- Departments of Applied Physics and Bioengineering, Stanford University, Stanford, California 94305
| | - Stephen R. Quake
- Howard Hughes Medical Institute, Stanford, California 94605
- Departments of Applied Physics and Bioengineering, Stanford University, Stanford, California 94305
| | - Matthias Meier
- Howard Hughes Medical Institute, Stanford, California 94605
- Departments of Applied Physics and Bioengineering, Stanford University, Stanford, California 94305
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14
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Abstract
Directed migration of Schwann cells (SC) is critical for development and repair of the peripheral nervous system. Understanding aspects of motility specific to SC, along with SC response to engineered biomaterials, may inform strategies to enhance nerve regeneration. Rat SC were cultured on laminin-coated microgrooved poly(dimethyl siloxane) platforms that were flat or presented repeating cellular scale anisotropic topographical cues, 30 or 60 µm in width, and observed with timelapse microscopy. SC motion was directed parallel to the long axis of the topography on both the groove floor and the plateau, with accompanying differences in velocity and directional persistence in comparison to SC motion on flat substrates. In addition, feature dimension affected SC morphology, alignment, and directional persistence. Plateaus and groove floors presented distinct cues which promoted differential motility and variable interaction with the topographical features. SC on the plateau surfaces tended to have persistent interactions with the edge topography, while SC on the groove floors tended to have infrequent contact with the corners and walls. Our observations suggest the capacity of SC to be guided without continuous contact with a topographical cue. SC exhibited a range of distinct motile morphologies, characterized by their symmetry and number of extensions. Across all conditions, SC with a single extension traveled significantly faster than cells with more or no extensions. We conclude that SC motility is complex, where persistent motion requires cellular asymmetry, and that anisotropic topography with cellular scale features can direct SC motility.
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Affiliation(s)
- Jennifer A. Mitchel
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Center for Biomedical Engineering, Brown University, Providence, Rhode Island, United States of America
| | - Diane Hoffman-Kim
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Center for Biomedical Engineering, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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15
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Abstract
Rapid prototyping of microfluidic systems using a combination of double-sided tape and PDMS (polydimethylsiloxane) is introduced. PDMS is typically difficult to bond using adhesive tapes due to its hydrophobic nature and low surface energy. For this reason, PDMS is not compatible with the xurography method, which uses a knife plotter and various adhesive coated polymer tapes. To solve these problems, a PDMS/tape composite was developed and demonstrated in microfluidic applications. The PDMS/tape composite was created by spinning it to make a thin layer of PDMS over double-sided tape. Then the PDMS/tape composite was patterned to create channels using xurography, and bonded to a PDMS slab. After removing the backing paper from the tape, a complete microfluidic system could be created by placing the construct onto nearly any substrate; including glass, plastic or metal-coated glass/silicon substrates. The bond strength was shown to be sufficient for the pressures that occur in typical microfluidic channels used for chemical or biological analysis. This method was demonstrated in three applications: standard microfluidic channels and reactors, a microfluidic system with an integrated membrane, and an electrochemical biosensor. The PDMS/tape composite rapid prototyping technique provides a fast and cost effective fabrication method and can provide easy integration of microfluidic channels with sensors and other components without the need for a cleanroom facility.
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Affiliation(s)
- Jungkyu Kim
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA.
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16
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Masuda T, Takahashi I, Anada T, Arai F, Fukuda T, Takano-Yamamoto T, Suzuki O. Development of a cell culture system loading cyclic mechanical strain to chondrogenic cells. J Biotechnol 2008; 133:231-8. [PMID: 17904677 DOI: 10.1016/j.jbiotec.2007.08.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 07/20/2007] [Accepted: 08/01/2007] [Indexed: 11/25/2022]
Abstract
Mechanical stimulation is considered to be one of the major epigenetic factors regulating the metabolism, proliferation, survival and differentiation of cells in the skeletal tissues. It is generally accepted that the cytoskeleton can undergo remodeling in response to mechanical stimuli such as tensile strain or fluid flow. Mechanically induced cell deformation is one of the possible mechanotransduction pathways by which chondrocytes sense and respond to changes in their mechanical environment. Mechanical strain has a variety of effects on the structure and function of their cells in the skeletal tissues, such as chondrocytes, osteoblasts and fibroblasts. However, little is known about the effect of the quality and quantity of mechanical strain and the timing of mechanical loading on the differentiation of these cells. The present study was designed to investigate the effect of the deformation of chondrogenic cells, and cyclic compression using a newly developed culture device, by analyzing mechanobiological response to the differentiating chondrocytes. Cyclic compression between 0 and 22% strains, at 23 microHz was loaded on chondrogenic cell line ATDC5 by seeding in a mass mode on PDMS membrane, assuming direct transfer of cyclic deformation from the membrane to the cells at the same frequency. The compressive strain, induced within the membrane, was characterized based on the analysis of the finite element modeling (FEM). The results showed that the tensile strain inhibits the chondrogenic differentiation of ATDC5 cells, whereas the compressive strain enhances the chondrogenic differentiation, suggesting that the differentiation of the chondrogenic cells could be controlled by the amount and the mode of strain. In conclusion, we have developed a unique strain loading culture system to analyze the effect of various types of mechanical stimulation on various cellular activities.
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Affiliation(s)
- Taisuke Masuda
- Division of Craniofacial Function Engineering (CFE), Tohoku University Graduate School of Dentistry, Sendai, Japan.
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17
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Xia XR, Baynes RE, Monteiro-Riviere NA, Riviere JE. A system coefficient approach for quantitative assessment of the solvent effects on membrane absorption from chemical mixtures. SAR QSAR Environ Res 2007; 18:579-93. [PMID: 17654338 DOI: 10.1080/10629360701428540] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A system coefficient approach is proposed for quantitative assessment of the solvent effects on membrane absorption from chemical mixtures. The complicated molecular interactions are dissected into basic molecular interaction forces via Abraham's linear solvation energy relationship (LSER). The molecular interaction strengths of a chemical are represented by a set of solute descriptors, while those of a membrane/chemical mixture system are represented by a set of system coefficients. The system coefficients can be determined by using a set of probe compounds with known solute descriptors. Polydimethylsiloxane (PDMS) membrane-coated fibres and 32 probe compounds were used to demonstrate the proposed approach. When a solvent was added into the chemical mixture, the system coefficients were altered and detected by the system coefficient approach. The system coefficients of the PDMS/water system were (0.09, 0.49, -1.11, -2.36, -3.78, 3.50). When 25% ethanol was added into the PDMS/water system, the system coefficients were altered significantly (0.38, 0.41, -1.18, -2.07, -3.40, 2.81); and the solvent effect was quantitatively described by the changes in the system coefficients (0.29, -0.08, -0.07, 0.29, 0.38, -0.69). The LSER model adequately described the experimental data with a correlation coefficient (r(2)) of 0.995 and F-value of 1056 with p-value less than 0.0001.
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Affiliation(s)
- X R Xia
- College of Veterinary Medicine, Center for Chemical Toxicology Research and Pharmacokinetics (CCTRP), North Carolina State University, Raleigh, NC, USA.
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18
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Abstract
Tissue engineering has promise as a means for repairing diseased and damaged tissues. A significant challenge in tissue construction relates to the constraints placed on tissue geometries resulting from diffusion limitations. An ability to incorporate a premade vasculature would overcome these difficulties and promote construct viability once implanted. Most in vitro microvascular fabrication strategies rely on surface-associated cell growth, manipulated cell monolayers, or random arrangement of cells within matrix materials. In contrast, we successfully suspended microvascular cells and isolated microvessel fragments within collagen and then microfluidically drove the mixtures into microfabricated network topologies. Developing within the 3D collagen matrix, patterned cells progressed into cord-like morphologies. These geometries were directed by the surrounding elastomer mold. With similar techniques, suspended fragments formed endothelial sprouts. By avoiding the addition of exogenous growth factors, we allowed constituent cells and fragments to autonomously develop within the constructs, providing a more physiologically relevant system for in vitro microvascular development. In addition, we present the first examples of directed endothelial cell sprouting from parent microvessel fragments. We believe this system may serve as a foundation for future in vivo fabrication of microvascular networks for tissue engineering applications.
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Affiliation(s)
- Carlos C Chang
- Biomedical Engineering Program, University of Arizona, Tucson, AZ 85724, USA
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19
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Guo XE, Takai E, Jiang X, Xu Q, Whitesides GM, Yardley JT, Hung CT, Chow EM, Hantschel T, Costa KD. Intracellular calcium waves in bone cell networks under single cell nanoindentation. Mol Cell Biomech 2006; 3:95-107. [PMID: 17263256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In this study, bone cells were successfully cultured into a micropatterned network with dimensions close to that of in vivo osteocyte networks using microcontact printing and self-assembled monolyers (SAMs). The optimal geometric parameters for the formation of these networks were determined in terms of circle diameters and line widths. Bone cells patterned in these networks were also able to form gap junctions with each other, shown by immunofluorescent staining for the gap junction protein connexin 43, as well as the transfer of gap-junction permeable calcein-AM dye. We have demonstrated for the first time, that the intracellular calcium response of a single bone cell indented in this bone cell network, can be transmitted to neighboring bone cells through multiple calcium waves. Furthermore, the propagation of these calcium waves was diminished with increased cell separation distance. Thus, this study provides new experimental data that support the idea of osteocyte network memory of mechanical loading similar to memory in neural networks.
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Affiliation(s)
- X Edward Guo
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
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20
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Mukhopadhyay R. E. coli stick to the right. Anal Chem 2005; 77:428A. [PMID: 16285142 DOI: 10.1021/ac053500p] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Khan GM, Frum Y, Sarheed O, Eccleston GM, Meidan VM. Assessment of drug permeability distributions in two different model skins. Int J Pharm 2005; 303:81-7. [PMID: 16102922 DOI: 10.1016/j.ijpharm.2005.07.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 06/24/2005] [Accepted: 07/02/2005] [Indexed: 11/22/2022]
Abstract
Past in vitro studies with human skin have indicated that drug permeability coefficient (Kp) distributions do not always follow a Gaussian-normal pattern. This has major statistical implications, exemplified by the fact that use of t-tests to evaluate significance is limited to normally distributed populations. Percutaneous absorption research often involves using animal or synthetic skins to simulate less readily available human skin. However, negligible work has been performed on assessing the permeability variabilities of these model membranes. This paper aims to fill this gap. To this end, four studies were undertaken representing two different drugs (caffeine and testosterone) with each drug penetrating through two different model skins (silicone membrane and pig skin). It was determined that in the silicone membrane studies, both compounds' Kp distributions could be fitted to a normal pattern. In contrast, in the pig skin studies, there were notable differences between each drug. While the testosterone Kp values could be fitted to a normal distribution, this was not possible with the caffeine Kp data, which could be fitted to a log-normal distribution. There is some evidence from the literature as well as physicochemical considerations that these outcomes may reflect general trends that are dependent upon both membrane and penetrant properties.
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Affiliation(s)
- Gul M Khan
- Department of Pharmaceutics, Faculty of Pharmacy, Gomal University, Dera Ismail Khan (NWFP), Pakistan
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22
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Caballero M, Bernal-Sprekelsen M, Calvo C, Farrè X, Quintó L, Alòs L. Polydimethylsiloxane versus polytetrafluoroethylene for vocal fold medialization: histologic evaluation in a rabbit model. J Biomed Mater Res B Appl Biomater 2004; 67:666-74. [PMID: 14528465 DOI: 10.1002/jbm.b.10061] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The objective is to study the tissue reaction of the paralyzed vocal cord in response to the injection of particulate plastics in a rabbit model. Forty-five New Zealand rabbits with surgical vocal-fold paralysis were used in the study. Histologic reactions of the larynx and the regional lymph nodes were analyzed by a single blinded pathologist at 6 weeks and 6 months after a vocal-cord injection of Teflon or of silicone elastomer. Macroscopic studies of the liver, lungs, spleen, kidney, and brain were performed. The histological study showed a greater proportion of chronic granulomatous inflammation in animals injected with silicone than in those injected with Teflon. The immunohistochemical study showed a higher degree of phagocytosis of Teflon particles than of the silicone particles. The silicone group presented a more severe fibrous reaction than the Teflon group, but the difference was not significant. No migration particles were found. It is concluded that silicone, having a greater viscosity than Teflon because of the size of its particles, induces more fibrosis and a larger proportion of foreign giant cells in the host. Due to this histological reaction, silicone particles present greater anchorage and stability.
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Affiliation(s)
- Miguel Caballero
- Department of Otorhinolaryngology, Hospital Clínic of Barcelona, Spain
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23
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Dey ES, Norrlöw O, Liu Y. Artificial carrier for oxygen supply in biological systems. Appl Microbiol Biotechnol 2004; 64:187-91. [PMID: 14593505 DOI: 10.1007/s00253-003-1454-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Revised: 09/04/2003] [Accepted: 09/07/2003] [Indexed: 11/27/2022]
Abstract
Several poly (dimethylsiloxanes) (PDMS) copolymers of dimethylsiloxane (DMS) with ethylene or propylene oxide were tested as artificial carriers for the delivery of oxygen to biological systems. Copolymers with a DMS content of 33% or lower enhanced glucose oxidation by 200% in contrast to the 25% increase produced by the same concentration of perfluorodecalin. When 0.05% of the copolymer with 18% DMS was included in the growth media of Bacillus thuriginensis, the biomass (growth rate) increased 1.5-fold. With 0.1% of this copolymer, actinorhodin production by Streptomyces coelicolor A3 (2) occurred in half the normal time and with an increased yield. In conclusion, these PDMS copolymers are a good alternative to perfluorodecalin as oxygen carriers in biotechnological processes.
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Affiliation(s)
- E S Dey
- Pure and Applied Biochemistry, Lund University, Box 124, 212 00, Lund, Sweden.
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24
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25
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Itoga K, Yamato M, Kobayashi J, Kikuchi A, Okano T. Micropatterned surfaces prepared using a liquid crystal projector-modified photopolymerization device and microfluidics. ACTA ACUST UNITED AC 2004; 69:391-7. [PMID: 15127385 DOI: 10.1002/jbm.a.30010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A commercial liquid crystal device projector was modified for photopolymerization using its on-board intense light source and a precision optical control circuit. This device projects reduced images generated by a typical personal computer onto the stage where photopolymerization on a surface occurs. This all-in-one device does not require expensive photomasks and external light sources. However, light scattering and diffraction through glass substrates resulted in undesired reactions in areas corresponding to masked (black) domains in mask patterns, limiting pattern resolution. To overcome this shortcoming, two-step surface patterning was developed. First, three-dimensional microstructures of crosslinked silicone elastomer were fabricated with this device and adhered onto silanized glass substrate surfaces, forming microchannels in patterns on the glass support. Then, acrylamide monomer solution containing photoreactive initiator was flowed into these micromold channels and reacted in situ. The resultant polyacrylamide layer was highly hydrophilic and repelled protein adsorption. Cell seeding on these patterns in serum-supplemented culture medium produced cells selectively adhered to different patterns: cells attached and spread only on unpolymerized silanized glass surfaces, not on the photopolymerized acrylamide surfaces. This technique should prove useful for inexpensive, rapid prototyping of surface micropatterns from polymer materials.
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Affiliation(s)
- Kazuyoshi Itoga
- Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, CREST-JST, Kawada-cho 8-1, Shinjuku-ku, Tokyo 162-8666, Japan
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26
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Harabagiu V, Fundueanu G, Pinteala M, Constantin M, Hamaide T. Bioapplication Oriented Polymers. Micro- and Nanoparticles for Drug Delivery Systems. Advances in Experimental Medicine and Biology 2004; 553:69-82. [PMID: 15503448 DOI: 10.1007/978-0-306-48584-8_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Valeria Harabagiu
- Petru Poni Institute of Macromolecular Chemistry, 700487 Iasi, Romania
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27
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Kurian P, Kasibhatla B, Daum J, Burns CA, Moosa M, Rosenthal KS, Kennedy JP. Synthesis, permeability and biocompatibility of tricomponent membranes containing polyethylene glycol, polydimethylsiloxane and polypentamethylcyclopentasiloxane domains. Biomaterials 2003; 24:3493-503. [PMID: 12809778 DOI: 10.1016/s0142-9612(03)00189-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The synthesis of "smart" tricomponent amphiphilic membranes containing poly(ethylene glycol) (PEG), polydimethylsiloxane (PDMS) and polypentamethylcyclopentasiloxane (PD(5)) domains is described. Contact angle hysteresis indicates that in air, the surfaces of such PEG/PD(5)/PDMS membranes are enriched by the hydrophobic components, PDMS and PD(5), while in water, the surfaces are rich in the hydrophilic PEG. The oxygen permeability of a series of membranes with varying M(c,hydrophilic) (M(n,PEG)=4600, 10,000 and 20,000 g/mol) and varying PEG/PD(5)/PDMS compositions was studied. Oxygen permeability increased with the amount of PDMS in the membrane. The molecular weight cut-off (MWCO) ranges and permeability coefficients of insulin through a series of PEG/PD(5)/PDMS(=29/14/57) membranes with varying M(c,hydrophilic) were determined. Insulin permeability is directly related to M(c,hydrophilic) of the membrane. MWCO studies show that the membranes are semipermeable to, i.e., allow the transport of smaller proteins such as insulin (M(n)=5733 g/mol, R(s)=1.34 nm) and cytochrome c (M(n)=12,400 g/mol, R(s)=1.63 nm), but are barriers to larger proteins such as albumin (M(n)=66,000 g/mol, R(s)=3.62 nm). Implantation of representative membranes in rats showed them to be biocompatible. According to these studies, PEG/PD(5)/PDMS membranes may be suitable for biological applications, e.g., immunoisolation of cells.
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Affiliation(s)
- P Kurian
- Institute of Polymer Science, The University of Akron, Akron, OH 44325-3909, USA
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28
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Abstract
The role of surface microtopography in combination with different surface wettability for rat calvaria cell differentiation was examined. Mineralization and alkaline phosphatase (ALP) activity of rat calvaria cells on flat polydimethylsiloxane (PDMS) or PDMS contained pyramids which were either hydrophilic or hydrophobic were compared. ALP expressing cells were more frequent on hydrophilic PDMS contained pyramids. ALP activity, peaked at day 9, was highest for hydrophilic pyramids followed by hydrophobic pyramids and flat hydrophilic PDMS surfaces. A similar pattern was obtained with respect to mineralized nodules. These observations showed that micro-sized surface features promote differentiation of rat calvaria cells. Further, hydrophilic surfaces are more prone to stimulate differentiation in comparison with hydrophobic surfaces. The results suggest that both material surface chemistry and topography affect osteoblast differentiation.
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Affiliation(s)
- Haihong Liao
- Department of Biomaterials, Box 412, Göteborg University, SE-405 30 Göteborg, Sweden
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29
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Mata A, Boehm C, Fleischman AJ, Muschler G, Roy S. Growth of connective tissue progenitor cells on microtextured polydimethylsiloxane surfaces. J Biomed Mater Res 2002; 62:499-506. [PMID: 12221697 DOI: 10.1002/jbm.10353] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Growth of human connective tissue progenitor cells (CTPs) was characterized on smooth and microtextured polydimethylsiloxane (PDMS) surfaces. Human bone-marrow-derived cells were cultured for 9 days under conditions promoting osteoblastic differentiation on smooth PDMS surfaces and on PDMS post microtextures that were 6 microm high and 5, 10, 20, and 40 microm in diameter, respectively. Glass tissue-culture dishes were used as controls. The number of viable cells was determined, and an alkaline phosphatase stain was used as a marker for osteoblastic phenotype. CTPs attached, proliferated, and differentiated on all surfaces. Cells on the smooth PDMS and control surfaces spread and proliferated as colonies in proximity to other cells and migrated in random directions, with cell process lengths of up to 80 microm. In contrast, cells on the PDMS post microtextures grew as sparsely distributed networks of cells, with processes, occasionally up to 300 microm, that appeared to interact with the posts. Cell counts revealed that there were fewer (50%) CTPs on the smooth PDMS surface than were on the glass control surfaces. However, there were consistently more (>144%) CTPs on the PDMS post textures than on the controls. In particular, the 10-microm-in-diameter posts (268%) exhibited a significantly (p < 0.05) greater cell number than did the smooth PDMS.
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Affiliation(s)
- Alvaro Mata
- BioMEMS Laboratory, Department of Biomedical Engineering (ND20), The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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30
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Abstract
Here we describe a method for quantifying traction in cells that are physically constrained within micron-sized adhesive islands of defined shape and size on the surface of flexible polyacrylamide gels that contain fluorescent microbeads (0.2-microm diameter). Smooth muscle cells were plated onto square (50 x 50 microm) or circular (25- or 50-microm diameter) adhesive islands that were created on the surface of the gels by applying a collagen coating through microengineered holes in an elastomeric membrane that was later removed. Adherent cells spread to take on the size and shape of the islands and cell tractions were quantitated by mapping displacement fields of the fluorescent microbeads within the gel. Cells on round islands did not exhibit any preferential direction of force application, but they exerted their strongest traction at sites where they formed protrusions. When cells were confined to squares, traction was highest in the corners both in the absence and presence of the contractile agonist, histamine, and cell protrusions were also observed in these regions. Quantitation of the mean traction exerted by cells cultured on the different islands revealed that cell tension increased as cell spreading was promoted. These results provide a mechanical basis for past studies that demonstrated a similar correlation between spreading and growth within various anchorage-dependent cells. This new approach for analyzing the spatial distribution of mechanical forces beneath individual cells that are experimentally constrained to defined sizes and shapes may provide additional insight into the biophysical basis of cell regulation.
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Affiliation(s)
- Ning Wang
- Physiology Program, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
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31
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Traina SJ, Fendinger NJ, McAvoy DC, Kerr KM, Gupta S. Fate of polydimethylsilicone in biosolids-amended field plots. J Environ Qual 2002; 31:247-55. [PMID: 11837429 DOI: 10.2134/jeq2002.2470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2000] [Indexed: 05/23/2023]
Abstract
This research examined the fate of polydimethylsilicones (PDMS) in agricultural test plots amended with municipal biosolids. This 4 yr field study involved addition of 0, 15, and 100 Mg ha(-1) of municipal biosolids, which contained ambient concentrations of PDMS (1272 mg kg(-1) biosolids), to corn and soybean test plots. Soil samples collected at intermittent time intervals were analyzed for soil water, soil organic C, extractable PDMS and PDMS hydrolysis products. Above normal precipitation during the field study maintained soil water levels in excess of 100 g kg(-1) for most of the testing period of 1994-1998. Under these conditions half-lives for PDMS (based on field dissipation data) ranged from 876 to 1443 d. When biosolids amended soil samples were brought into the laboratory and subjected to more rapid drying, >80% of the PDMS was transformed to lower molecular weight hydrolysis products within 20 d. No difference in relative PDMS transformation rates were evident for soils that received PDMS in the form of a biosolids amendment or directly dosed to the soil (in the absence of biosolids) indicating little if any effect of direct PDMS-biosolids interactions on PDMS transformation rates. These results support that the overriding factor controlling the fate of PDMS in field soils is the soil moisture content.
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Affiliation(s)
- Samuel J Traina
- School of Natural Resources, The Ohio State University, Columbus 43210, USA.
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32
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Berrocal MJ, Badr IH, Gao D, Bachas LG. Reducing the thrombogenicity of ion-selective electrode membranes through the use of a silicone-modified segmented polyurethane. Anal Chem 2001; 73:5328-33. [PMID: 11721937 DOI: 10.1021/ac010375i] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The susceptibility of segmented polyurethanes (SPUs) to in vivo oxidative cleavage and hydrolysis constitutes a drawback in the use of these materials in the fabrication of implantable devices. The introduction of poly(dimethylsiloxane) (PDMS) groups into the polymer main chain has been previously reported to enhance the stability of SPUs. Herein, we evaluated the use of BioSpan-S, a silicone-modified SPU, in the design of membranes for cation-selective electrodes. The resulting electrodes exhibited good potentiometric response with all of the tested ionophores (valinomycin, sodium ionophore X, and nonactin). The obtained selectivity coefficients meet the selectivity requirements for the determination of sodium and potassium in blood. Moreover, as reflected by SEM studies, membranes prepared with BioSpan-S showed less adhesion of platelets than membranes prepared with conventional poly(vinyl chloride) (PVC). These results lead to the conclusion that BioSpan-S would be an appropriate candidate for the fabrication of implantable ion-selective electrodes.
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Affiliation(s)
- M J Berrocal
- Department of Chemistry and Center of Membrane Sciences, University of Kentucky, Lexington 40506-0055, USA
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33
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Affiliation(s)
- J Hyun
- Department of Biomedical Engineering Duke University, Box 90281 Durham, North Carolina 27708-0281, USA
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34
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Abstract
Silicone polymers (PDMS = polydimethylsiloxane) are used in numerous consumer and industrial products. Our previous work showed that they will degrade in soil under laboratory conditions. This paper investigates PDMS degradation in the field. Four soil plots (each 2.44 m x 2.44 m) in Michigan were sprayed in May, 1997, with aqueous emulsion to achieve nominal soil PDMS concentrations of 0 (control), 215 (low), 430 (medium), and 860 (high) microg/g. Over the following summer, soil cores (0-5 and 5-10 cm) were collected every two weeks and analyzed for decrease in-total soil PDMS, and decrease in molecular weight of remaining PDMS. PDMS concentrations decreased 50% in 4.5, 5.3, and 9.6 weeks for the low, medium, and high treatments, respectively. Degradation rates were 0.26 (low), 0.44 (medium), and 0.44 (high) g PDMS/m2 day, indicating that degradation capacity of the soil was exceeded by the High treatment. Dimethylsilanediol (DMSD), the main degradation product, was detected in most samples at <5% of original PDMS. This is consistent with laboratory data showing biodegradation and volatilization of DMSD. Deeper sampling (to 20 cm) found only trace amounts of DMSD, and minor downward movement of the polymer. Respraying and subsequent analysis of one plot with a medium treatment in late August showed slow PDMS degradation during the cool, wet fall, followed by a 40% decrease over winter and extensive degradation during the summer of 1998. The study thus shows that PDMS will degrade under field conditions as predicted from laboratory experiments.
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Affiliation(s)
- R G Lehmann
- Health and Environmental Sciences, Dow Corning Corporation, Midland, Michigan 48686-0994, USA.
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35
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Abstract
The microbial degradation of low-molecular-weight polydimethylsiloxanes was investigated through laboratory experiments. Octamethylcyclotetrasiloxane was found to be biodegraded under anaerobic conditions in composted sewage sludge, as monitored by the occurrence of the main polydimethylsiloxane degradation product, dimethylsilanediol, compared to that found in experiments with sterilized control samples.
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Affiliation(s)
- R Grümping
- Institute of Environmental Analytical Chemistry, University of Essen, D-45177 Essen, Germany.
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36
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Abstract
Due to their insolubility in water and high adsorption coefficient, liquid polydimethylsiloxanes (PDMS) discharged as effluent will adsorb to particulate matter and, therefore, will become a component of sewage sludge during waste water treatment. The subsequent environmental fate of PDMS will depend on the fate of the sludge. Due to increasing practices of soil amendment with sewage sludge the principal environmental compartment receiving PDMS fluids is the soil. Degradation of PDMS is a common process taking place in many different types of soils. It occurs through a unique combination of environmental degradation processes. Initial hydrolysis of PDMS is catalysed by clay minerals, the principal component of soil. The primary hydrolysis product, dimethylsilanediol (DMSD), is then either biodegraded, or evaporated into the atmosphere, where it is subsequently oxidised in the presence of sunlight. The end products in both cases are expected to be CO2, SiO2 and H2O.
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Affiliation(s)
- E F Griessbach
- Health, Environmental & Regulatory Affairs, Dow Corning Europe, La Hulpe, Belgium
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37
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Kirkbride KP, Klass G, Pigou PE. Application of solid-phase microextraction to the recovery of organic explosives. J Forensic Sci 1998; 43:76-81. [PMID: 9456529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The application of solid-phase microextraction to the recovery of residues of organic explosives by headspace sampling is discussed. It was found that the technique was rapid and simple. Polydimethylsiloxane and polyacrylate resin were examined as adsorption phases and the latter was found to be more effective. It was found that non-volatile explosives (PETN, RDX, and TNT) should be extracted at about 100 degrees. Acceptable limits of detection were achieved using bench top quadrupole mass spectrometry and short extraction times (about 30 min). Increasing the extraction times to many hours resulted in significantly enhanced detection. Desorption of PETN from the solid phase was found to induce some decomposition of the explosive, but the technique was still valuable for the analysis of this compound.
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38
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Butler JE, Navarro P, Lü EP. Comparative studies on the interaction of proteins with a polydimethylsiloxane elastomer. II. The comparative antigenicity of primary and secondarily adsorbed IgG1 and IgG2a and their non-adsorbed counterparts. J Mol Recognit 1997; 10:52-62. [PMID: 9179779 DOI: 10.1002/(sici)1099-1352(199701/02)10:1<52::aid-jmr354>3.0.co;2-n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The antigenicity of bovine IgG1 and IgG2a adsorbed on a polydimethysiloxane (PEP) elastomer, on a widely used polystyrene (Imm 2, Dynatech) or immobilized as biotinylated proteins to streptavidin covalently bound to polystyrene (SA-PS) was compared using various monoclonal (mAbs) and polyclonal antibodies (pAb) to bovine IgG. The IgGs were either adsorbed as native proteins or pre-denatured with 6M Guanidine-HCl (Gu-HCl) or 6 M Gu-HCl/0.1% 2-mercaptoethanol. In special situations, bovine and human IgG was immobilized by secondary adsorption to an albumin monolayer adsorbed on either PEP or Imm 2. Results indicate that pre-denaturation of IgGs with 6 M Gu-HCl/2-mercaptoethanol destroys all antigenicity whereas those IgGs pretreated with 6 M-GuHCl are indistinguishable in their antigenicity from the IgGs adsorbed to either PEP or Imm 2 without such treatment. When immobilized on SA-PS, Gu-HCl-treated IgGs were significantly less detectable, especially when tested using mAbs. In general, IgGs adsorbed on PEP or Imm 2 were less antigenic than when immobilized on SA-PS. However, two monoclonals specific for the IgG2a(A2) allotypic variant, favored the adsorbed protein and one polyclonal best recognized the IgG2a(A1) variant adsorbed on Imm 2 rather than when adsorbed on PEP or immobilized on SA-PS. Both IgG1 and IgG2a, bound by apparent protein-protein interactions to an albumin monolayer, were significantly more detectable than when directly adsorbed on either Imm 2 or PEP. Using 125I-antibody or its Fab fragment to reduce steric hindrance in detection, we observed the same differences in detectability as when measured by enzyme-linked immunosorbent assay. Failure to identify a steric hindrance effect and the preference of some antibodies for adsorbed allotypic variants, support the concept of adsorption-induced conformational change (AICC). We conclude that proteins adsorbed as a monolayer on the PEP elastomer used to form the envelope of silicone breast implants are conformationally altered, but not necessarily to the same extent or the same manner as when adsorbed on polystyrene. The significantly great antigenicity of secondarily adsorbed IgG suggests that it may be present in near native conformation.
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Affiliation(s)
- J E Butler
- Department of Microbiology, University of Iowa, Iowa City 52242-1109, USA
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39
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Butler JE, Lü EP, Navarro P, Christiansen B. Comparative studies on the interaction of proteins with a polydimethylsiloxane elastomer. I. Monolayer protein capture capacity (PCC) as a function of protein pl, buffer pH and buffer ionic strength. J Mol Recognit 1997; 10:36-51. [PMID: 9179778 DOI: 10.1002/(sici)1099-1352(199701/02)10:1<36::aid-jmr353>3.0.co;2-g] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Polydimethylsiloxane (PEP) is widely used in medical prostheses and therefore is in contact with plasma and secretory proteins. Two pair of globular proteins, lactoferrin (Lf) and transferrin (Trf), and bovine IgG1 and IgG2a, which differ substantially between pair members in their pl, were used to study the interaction of a PEP widely used in breast implants and soluble protein. Studies were done using iodinated proteins over a concentration range that resulted in an apparent protein monolayer. Secondary incubations with dilute protein solutions were needed to form the monolayer on PEP, possibly as a consequence of micro air bubbles trapped on its highly textured surface as shown by atomic force microscopy. Immunoassay quality polystyrene microtiter wells were used as controls. Adsorption studies were routinely performed at pH 4, 7 and 10 and at ionic strengths corresponding to 0.95, 9.5 and 90.0 mS. The protein capture capacity (PCC) of PEP for Lf and Trf was optimal at physiological pH and ionic strength and comparable under these conditions to that of Immulon 2 (Imm 2) microtiter wells. While increasing the ionic strength and pH further increases the PCC of Imm 2 for Lf and Trf, this markedly lowered the PCC of PEP for these proteins suggesting that initial polar interactions may precede subsequent hydrophobic bonding to PEP. This was tested using a hydrophilic variant of PEP, which when tested in a 90.0 mS buffer, showed a > five-fold lower PCC at neutral and alkaline pH. The greatly reduced PCC of the hydrophilic variant might also suggest that hydrophilic variants of silicone would be more biocompatible than those currently used. The PCC of PEP for the IgGs was less than that of Imm 2 but still optimal at physiological conditions. Consistent with the data on Lf/Trf, PCC progressively decreased with increasing ionic strength at alkaline pH. Differences in pl between the protein pairs had only a marginal effect on the PCC of PEP. Monolayer adsorption on both PEP and Imm 2 was slowly reversible and greater in the presence of free ligand (< 2% in 16 h) suggesting that the process follows Mass Law principles. However, even in the presence of non-ionic detergent and free ligand, 85-90% remained bound on either surface. Thus, desorption of proteins in the monolayer should not complicate subsequent immunochemical studies conducted on adsorbed monolayers.
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Affiliation(s)
- J E Butler
- Department of Microbiology, University of Iowa Medical School, Iowa City 52242, USA
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40
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Abstract
The biodegradation potential of [14C]dimethylsilanediol, the monomer unit of polydimethylsiloxane, in soils was investigated. Dimethylsilanediol was found to be biodegraded in all of the tested soils, as monitored by the production of 14CO2. When 2-propanol was added to the soil as a carbon source in addition to [14C]dimethylsilanediol, the production of 14CO2 increased. A method for the selection of primary substrates that support cometabolic degradation of a target compound was developed. By this method, the activity observed in the soils was successfully transferred to liquid culture. A fungus, Fusarium oxysporum Schlechtendahl, and a bacterium, an Arthrobacter species, were isolated from two different soils, and both microorganisms were able to cometabolize [14C]dimethylsilanediol to 14CO2 in liquid culture. In addition, the Arthrobacter sp. that was isolated grew on dimethylsulfone, and we believe that this is the first reported instance of a microorganism using dimethylsulfone as its primary carbon source. Previous evidence has shown that polydimethylsiloxane is hydrolyzed in soil to the monomer, dimethylsilanediol. Now, biodegradation of dimethylsilanediol in soil has been demonstrated.
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Affiliation(s)
- C L Sabourin
- Environmental Laboratory, General Electric Corporate Research and Development, Schenectady, New York 12301, USA.
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41
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Furuzono T, Kishida A, Yanagi M, Matsumoto T, Kanda T, Nakamura T, Aiko T, Maruyama I, Akashi M. Novel functional polymers: poly(dimethylsiloxane)-polyamide multiblock copolymer. V. The interaction between biomolecules and the surface of aramid-silicone resins. J Biomater Sci Polym Ed 1996; 7:871-80. [PMID: 8836833 DOI: 10.1163/156856296x00048] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Multiblock copolymers consisting of aromatic polyamide(aramid) and poly(dimethylsiloxane) (PDMS) aramid-silicone resins (PASs) were synthesized by low temperature solution polycondensation, and PAS films were prepared by casting from an N,N'-dimethylacetamide solution. In this study, we investigated bovine serum albumin (BSA) adsorption, L929 cell adhesion, and tissue reaction on the surface of PAS in order to clarify the interaction between PAS and biomolecules. It was found that the amount of adsorbed biomolecules on PAS was extremely low in contrast with those on aramid and nylon films, and it was comparable to SILASTIC 500-1 film. This suppression of adsorption of biomolecules onto PAS seemed to be due to the low surface free energy of the outermost surface of PAS, where PDMS block was condensed.
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Affiliation(s)
- T Furuzono
- Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, Japan
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42
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Anderson JM, Ziats NP, Azeez A, Brunstedt MR, Stack S, Bonfield TL. Protein adsorption and macrophage activation on polydimethylsiloxane and silicone rubber. J Biomater Sci Polym Ed 1996; 7:159-69. [PMID: 7654630 DOI: 10.1163/156856295x00670] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Static and dynamic human blood adsorption studies on polydimethylsiloxane, PDMS, and silicone rubber show that these materials are similar, but not identical, in their protein adsorption behavior. Fibrinogen, immunoglobulin G, and albumin were the predominant proteins identified on the material surfaces with fibronectin, Hageman factor (factor XII), and factor VIII/vWF adsorbing at intermediate levels. While the protein adsorption characteristics for the two materials were similar, higher levels of the respective proteins were identified on silicone rubber compared to PDMS. Monocytes/macrophages incubated on PDMS, silicone rubber and low density polyethylene, LDPE, with or without protein adsorption produced variable levels of IL-1 beta, IL-6 and TNF-alpha dependent on the polymer and adsorbed protein. PDMS showed lower levels of the cytokines when compared to the polystyrene control and polyethylene. Protein preadsorption on the PDMS, polystyrene, and LDPE surfaces showed lower levels of cytokines when compared to the respective quantities produced with no protein adsorption suggesting a passivating effect by the protein adsorption phenomenon on monocyte/macrophage activation. Preadsorption of IgG, fibrinogen or fibronectin decreased the quantitative expression of IL-1 beta but increased the functional activity in the thymocyte proliferation assay indicating the presence of monocyte/macrophage activation products which either downregulated the activity of IL-1 beta or upregulated thymocyte proliferation in an independent fashion.
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Affiliation(s)
- J M Anderson
- Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106-4907, USA
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43
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Abstract
In order to study the aging process (i.e., silicone migration, fat infiltration) of silicone (polydimethylsiloxane, PDMS) based biomaterials in living subjects by NMR imaging, a hybrid 1H selective excitation and saturation chemical shift imaging technique (IR/CHESS-CSSE) has been developed. This sequence allows selective mapping of the distribution of silicone protons in vivo, while suppressing the contributions of fat and water. Our results indicate that a combined inversion recovery and CHESS pulse, followed by a spoiler gradient, must be applied to suppress all contributions of fat protons to the NMR signal. The sensitivity of our experiments allows the detection of a chemically unchanged silicone concentration of 5% in a voxel of 0.9 mm3 at a signal/noise ratio of 2.
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Affiliation(s)
- B Pfleiderer
- Department of Radiology, Massachusetts General Hospital, Charlestown 02129
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44
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Kawakami T, Nakakamura C, Hasegawa H, Eda S. Fate of 14C-labelled dimethylpolysiloxane (silicone oil) in a root canal filling material embedded in rat subcutaneous tissues. Dent Mater 1987; 3:256-60. [PMID: 3479362 DOI: 10.1016/s0109-5641(87)80083-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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45
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Watanabe N, Nakamura T, Watanabe E, Sato E, Ose Y. Bioconcentration potential of polydimethylsiloxane (PDMS) fluids by fish. Sci Total Environ 1984; 38:167-172. [PMID: 6523120 DOI: 10.1016/0048-9697(84)90214-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The water solubilities (S), octanol/water partition coefficients (KOW) and bioconcentration factors (BCF) of four polydimethylsiloxane (PDMS) fluids covering a wide range of molecular weight were measured. It is shown that a previously described correlation between S and KOW for organic chemicals may be invalid for PDMS fluids; an alternative correlation is proposed. Some PDMS fluids tend to have a bioconcentration potential in silver carp.
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46
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Abstract
The use of correlated microscopic techniques, including the scanning electron microscopic modes of backscattered electron imaging and energy dispersive x-ray analysis, aid in defining the process of dispersion of silicon-containing material around silicone rubber (polydimethylsiloxane) prosthetic devices.
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