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Johnson D, Kim U, Mobed-Miremadi M. Nanocomposite films as electrochemical sensors for detection of catalase activity. Front Mol Biosci 2022; 9:972008. [PMID: 36225256 PMCID: PMC9549927 DOI: 10.3389/fmolb.2022.972008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 08/23/2022] [Indexed: 11/17/2022] Open
Abstract
Cross-linked hydrogel substrates have garnered attention as they simultaneously enable oxidoreductase reactions in a control volume extended to adsorption of redox capacitors for amplification of electrochemical signals. In this study, the effect of catalase immobilization in mold-casted alginate-based thin films (1 mm × 6 mm × 10 mm) containing multi walled carbon nanotubes (MWCNT) coated with chitosan has been studied via amperometry. The amperometric response was measured as a function of peroxide concentration, at a fixed potential of −0.4 V vs. SPCE in phosphate-buffered saline (pH = 7.4). Results indicate substrate detection is not diffusion-limited by the 100 μm thick chitosan layer, if the cationic polyelectrolyte is in contact with the sensing carbon electrode, and the linear detection of the enzyme absent in solution is enabled by immobilization (R2 = 0.9615). The ferricyanide-mediated biosensor exhibited a sensitivity of 4.55 μA/mM for the optimal formulation at room temperature comparable to other nanomaterial hybrid sensing solution namely amine-functionalized graphene with an average response time of 5 s for the optimal formulation. The suitability of the optimized chitosan-coated alginate slabs nano-environment for co-encapsulation of catalase and carbon nanotubes was confirmed by cyclic voltammetry.
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Affiliation(s)
| | - Unyoung Kim
- *Correspondence: Unyoung Kim, ; Maryam Mobed-Miremadi,
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2
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Mut SR, Mishra S, Vazquez M. A Microfluidic Eye Facsimile System to Examine the Migration of Stem-like Cells. MICROMACHINES 2022; 13:mi13030406. [PMID: 35334698 PMCID: PMC8954941 DOI: 10.3390/mi13030406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 02/24/2022] [Accepted: 02/24/2022] [Indexed: 02/05/2023]
Abstract
Millions of adults are affected by progressive vision loss worldwide. The rising incidence of retinal diseases can be attributed to damage or degeneration of neurons that convert light into electrical signals for vision. Contemporary cell replacement therapies have transplanted stem and progenitor-like cells (SCs) into adult retinal tissue to replace damaged neurons and restore the visual neural network. However, the inability of SCs to migrate to targeted areas remains a fundamental challenge. Current bioengineering projects aim to integrate microfluidic technologies with organotypic cultures to examine SC behaviors within biomimetic environments. The application of neural phantoms, or eye facsimiles, in such systems will greatly aid the study of SC migratory behaviors in 3D. This project developed a bioengineering system, called the μ-Eye, to stimulate and examine the migration of retinal SCs within eye facsimiles using external chemical and electrical stimuli. Results illustrate that the imposed fields stimulated large, directional SC migration into eye facsimiles, and that electro-chemotactic stimuli produced significantly larger increases in cell migration than the individual stimuli combined. These findings highlight the significance of microfluidic systems in the development of approaches that apply external fields for neural repair and promote migration-targeted strategies for retinal cell replacement therapy.
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Affiliation(s)
- Stephen Ryan Mut
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Rd, Piscataway, NJ 08854, USA;
| | - Shawn Mishra
- Regeneron, 777 Old Saw Mill River Rd, Tarrytown, NY 10591, USA;
| | - Maribel Vazquez
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Rd, Piscataway, NJ 08854, USA;
- Correspondence:
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3
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Li W, Zhao K, Chen X, Li Y. Dielectric Analysis of Microcapsule-Immobilized Composite Capsules Suspension: Substances Release. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:966-971. [PMID: 31941280 DOI: 10.1021/acs.langmuir.9b03539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dielectric spectroscopy has unique advantages in monitoring drug release. In this work, a dielectric measurement was carried out on the release of the substances of microcapsule-immobilized composite capsules, which were fabricated by encapsulating the Perinereis aibuhitensis extract-loaded gum Arabic/gelatin microcapsules (PaE: GA/GE-MCs) in calcium alginate hydrogel (PaE: CA/GA/GE-CCs). We established the dielectric model of PaE: CA/GA/GE-CCs and got in-depth information on the systems. There are two relaxations in the dielectric spectroscopy, both of which are caused by interfacial polarization. The relaxation mechanisms correspond to the interfacial polarization of the PaE-loading core/calcium alginate shell interface and the calcium alginate shell/solution interface, respectively. Besides, the swelling of composite capsules and substance migration in the composite capsules were observed by analyzing phase parameters. Finally, the characteristic release of calcium alginate composite capsules was confirmed, and the substance release mechanism of composite capsules, namely, the swelling-diffusion mechanism, was obtained.
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Affiliation(s)
- Wantong Li
- College of Chemistry , Beijing Normal University , Beijing 100875 , China
| | - Kongshuang Zhao
- College of Chemistry , Beijing Normal University , Beijing 100875 , China
| | - Xiguang Chen
- Biochemistry and Biomaterial Key Laboratory of Shandong Colleges and Universities, College of Marine Life Science , Ocean University of China , Yushan Road , Qingdao , Shandong 266003 , China
| | - Yang Li
- Biochemistry and Biomaterial Key Laboratory of Shandong Colleges and Universities, College of Marine Life Science , Ocean University of China , Yushan Road , Qingdao , Shandong 266003 , China
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4
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Konch TJ, Bora AP, Raidongia K. Disposable Fluidic Devices of Bionanochannels for Enzymatic Monitoring and Energy Harvesting. ACS APPLIED BIO MATERIALS 2019; 2:2549-2556. [PMID: 35030709 DOI: 10.1021/acsabm.9b00249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nature produces a plethora of nanochannels to carry out highly complex biological tasks in a sophisticated manner. There have been several studies to understand the characteristics of these channels; however, efforts to apply them for technological advancements are still scarce. Here, we have demonstrated that the fluidic channels of biomaterials can be harvested as nanofluidic devices to produce energy from enzymatic chemical reactions. The bionanochannel-based nanofluidic devices exhibit various nanofluidic phenomena like surface-charged-governed ionic conductivity and development of the transmembrane potential. The mobility of ions in the hydrated bionanochannels are found to be higher than that of bulk water. The cation-selective nature of the biochannels was also exploited to harvest a continuous supply of power up to 74 mW m-2 for 3 h from the enzymatic decomposition of urea. The transmembrane potential across the biochannels was also explored for label-free electrical monitoring of the enzymatic reaction inside the biological medium. Electrical monitoring on the kinetics of urease at different reaction temperatures suggested that inside biological medium the reaction goes through a pathway of lower activation energy (31.1 kJ) than that in the bulk environment (34.1 kJ). Enzyme urease was found to be more sustainable in bionanochannels than in glass vials.
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Affiliation(s)
- Tukhar Jyoti Konch
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Akash Protim Bora
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Kalyan Raidongia
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
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5
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Kajisa T, Li W, Michinobu T, Sakata T. Well-designed dopamine-imprinted polymer interface for selective and quantitative dopamine detection among catecholamines using a potentiometric biosensor. Biosens Bioelectron 2018; 117:810-817. [DOI: 10.1016/j.bios.2018.07.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 07/05/2018] [Accepted: 07/09/2018] [Indexed: 01/07/2023]
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6
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Pandimurugan R, Thambidurai S. UV protection and antibacterial properties of seaweed capped ZnO nanoparticles coated cotton fabrics. Int J Biol Macromol 2017; 105:788-795. [DOI: 10.1016/j.ijbiomac.2017.07.097] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/02/2017] [Accepted: 07/15/2017] [Indexed: 12/11/2022]
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7
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Izadifar M, Babyn P, Kelly ME, Chapman D, Chen X. Bioprinting Pattern-Dependent Electrical/Mechanical Behavior of Cardiac Alginate Implants: Characterization and Ex Vivo Phase-Contrast Microtomography Assessment. Tissue Eng Part C Methods 2017; 23:548-564. [PMID: 28726575 DOI: 10.1089/ten.tec.2017.0222] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Three-dimensional (3D)-bioprinting techniques may be used to modulate electrical/mechanical properties and porosity of hydrogel constructs for fabrication of suitable cardiac implants. Notably, characterization of these properties after implantation remains a challenge, raising the need for the development of novel quantitative imaging techniques for monitoring hydrogel implant behavior in situ. This study aims at (i) assessing the influence of hydrogel bioprinting patterns on electrical/mechanical behavior of cardiac implants based on a 3D-printing technique and (ii) investigating the potential of synchrotron X-ray phase-contrast imaging computed tomography (PCI-CT) for estimating elastic modulus/impedance/porosity and microstructural features of 3D-printed cardiac implants in situ via an ex vivo study. Alginate laden with human coronary artery endothelial cells was bioprinted layer by layer, forming cardiac constructs with varying architectures. The elastic modulus, impedance, porosity, and other structural features, along with the cell viability and degradation of printed implants were examined in vitro over 25 days. Two selected cardiac constructs were surgically implanted onto the myocardium of rats and 10 days later, the rat hearts with implants were imaged ex vivo by means of PCI-CT at varying X-ray energies and CT-scan times. The elastic modulus/impedance, porosity, and structural features of the implant were inferred from the PCI-CT images by using statistical models and compared with measured values. The printing patterns had significant effects on implant porosity, elastic modulus, and impedance. A particular 3D-printing pattern with an interstrand distance of 900 μm and strand alignment angle of 0/45/90/135° provided relatively higher stiffness and electrical conductivity with a suitable porosity, maintaining high cell viability over 7 days. The X-ray photon energy of 30-33 keV utilizing a CT-scan time of 1-1.2 h resulted in a low-dose PCI-CT, which provided a good visibility of the low-X-ray absorbent alginate implants. After 10 days postimplantation, the PCI-CT provided a reasonably accurate estimation of implant strand thickness and alignment, pore size and interconnectivity, porosity, elastic modulus, and impedance, which were consistent with our measurements. Findings from this study suggest that 3D-printing patterns can be used to modulate electrical/mechanical behavior of alginate implants, and PCI-CT can be potentially used as a 3D quantitative imaging tool for assessing structural and electrical/mechanical behavior of hydrogel cardiac implants in small animal models.
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Affiliation(s)
- Mohammad Izadifar
- 1 Division of Biomedical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada .,2 Department of Surgery, College of Medicine, University of Saskatchewan , Saskatoon, Canada .,3 Department of Mechanical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada
| | - Paul Babyn
- 1 Division of Biomedical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada .,4 Department of Medical Imaging, College of Medicine, University of Saskatchewan , Saskatoon, Canada
| | - Michael E Kelly
- 1 Division of Biomedical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada .,2 Department of Surgery, College of Medicine, University of Saskatchewan , Saskatoon, Canada
| | - Dean Chapman
- 1 Division of Biomedical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada .,4 Department of Medical Imaging, College of Medicine, University of Saskatchewan , Saskatoon, Canada .,5 Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan , Saskatoon, Canada
| | - Xiongbiao Chen
- 1 Division of Biomedical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada .,3 Department of Mechanical Engineering, College of Engineering, University of Saskatchewan , Saskatoon, Canada
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Bekin S, Sarmad S, Gürkan K, Yenici G, Keçeli G, Gürdağ G. Dielectric, thermal, and swelling properties of calcium ion-crosslinked sodium alginate film. POLYM ENG SCI 2013. [DOI: 10.1002/pen.23678] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Seda Bekin
- Department of Chemical Engineering; Faculty of Engineering; Istanbul University; 34320 Avcilar Istanbul Turkey
| | - Shokat Sarmad
- Department of Chemical Engineering; Faculty of Engineering; Istanbul University; 34320 Avcilar Istanbul Turkey
| | - Koray Gürkan
- Department of Electrical and Electronics Engineering; Faculty of Engineering; Istanbul University; 34320 Avcilar Istanbul Turkey
| | - Gökçen Yenici
- Department of Chemical Engineering; Faculty of Engineering; Istanbul University; 34320 Avcilar Istanbul Turkey
| | - Gönül Keçeli
- Department of Chemistry; Faculty of Engineering; Istanbul University; 34320 Avcilar Istanbul Turkey
| | - Gülten Gürdağ
- Department of Chemical Engineering; Faculty of Engineering; Istanbul University; 34320 Avcilar Istanbul Turkey
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9
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Aimé C, Coradin T. Nanocomposites from biopolymer hydrogels: Blueprints for white biotechnology and green materials chemistry. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/polb.23061] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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10
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Lin YH, Yang YW, Chen YD, Wang SS, Chang YH, Wu MH. The application of an optically switched dielectrophoretic (ODEP) force for the manipulation and assembly of cell-encapsulating alginate microbeads in a microfluidic perfusion cell culture system for bottom-up tissue engineering. LAB ON A CHIP 2012; 12:1164-73. [PMID: 22322420 DOI: 10.1039/c2lc21097e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This study reports the utilisation of an optically switched dielectrophoretic (ODEP) force for the manipulation and assembly of cell-encapsulating alginate microbeads in a microfluidic perfusion cell culture system for bottom-up tissue engineering. One of the key features of this system is the ODEP force-based mechanism, which allows a commercial projector to be coupled with a computer to manipulate and assemble cell-encapsulating microbeads in an efficient, manageable, and user-friendly manner. Another distinctive feature is the design of the microfluidic cell culture chip, which allows the patterned cell-encapsulating microbeads to be cultivated on site under culture medium perfusion conditions. For demonstrating its application in bottom-up cartilage tissue engineering, chondrocyte-encapsulating alginate microbeads varying in encapsulated cell densities were generated. The manipulation forces associated with operating the alginate microbeads were experimentally evaluated. The results revealed that the measured manipulation forces increased with increases in both the applied electric voltage and the number of cells in the alginate microbeads. Nevertheless, the observed manipulation force was found to be independent of the size of the cell-free alginate microbeads. It can be speculated that the friction force may influence the estimation of the ODEP force within the experimental conditions investigated. In this study, chondrocyte-encapsulating alginate microbeads with three different cell densities were manipulated and assembled in the proposed microfluidic system to form a compact sheet-like cell culture construct that imitates the cell distribution in the cross-section of native articular cartilage. Moreover, the demonstration case also showed that the cell viability of the cultured cells in the microfluidic system remained as high as 96 ± 2%. In this study, four sheet-like cell culture constructs were stacked to create a larger assembled cell culture construct. The cell distribution inside the cell culture construct was further confirmed by a confocal microscopy observation, which showed that the distribution was similar to that in native articular cartilage. As a whole, the proposed system holds great promise as a platform for engineering tissue constructs with easily tunable inner cell distributions.
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Affiliation(s)
- Yen-Heng Lin
- Department of Electronic Engineering, Chang Gung University, Taoyuan, Taiwan
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11
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Schneider S, Feilen P, Cramer H, Hillgärtner M, Brunnenmeier F, Zimmermann H, Weber MM, Zimmermann U. Beneficial effects of human serum albumin on stability and functionality of alginate microcapsules fabricated in different ways. J Microencapsul 2010. [DOI: 10.3109/02652040309178351] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- S. Schneider
- Schwerpunkt Endokrinologie und Stoffwechseler Krankungen, I. Medizinische Klinik und Poliklinik, Universitäts-Klinik Mainz, 55131, Mainz, Germany
| | - P. Feilen
- Schwerpunkt Endokrinologie und Stoffwechseler Krankungen, I. Medizinische Klinik und Poliklinik, Universitäts-Klinik Mainz, 55131, Mainz, Germany
| | - H. Cramer
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, 97074, Würzburg, Germany
| | - M. Hillgärtner
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, 97074, Würzburg, Germany
| | - F. Brunnenmeier
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, 97074, Würzburg, Germany
| | - H. Zimmermann
- Arbeitsgruppe Tieftemperatur-Biophysik, Fraunhofer Institut für Biomedizinische Technik (IBMT), 66386, St Ingbert, Germany
| | - M. M. Weber
- Schwerpunkt Endokrinologie und Stoffwechseler Krankungen, I. Medizinische Klinik und Poliklinik, Universitäts-Klinik Mainz, 55131, Mainz, Germany
| | - U. Zimmermann
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, 97074, Würzburg, Germany
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12
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Westhoff M, Zimmermann D, Zimmermann G, Gessner P, Wegner LH, Bentrup FW, Zimmermann U. Distribution and function of epistomatal mucilage plugs. PROTOPLASMA 2009; 235:101-105. [PMID: 19145400 DOI: 10.1007/s00709-008-0029-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Accepted: 12/17/2008] [Indexed: 05/27/2023]
Abstract
Investigation of 67 gymnosperm and angiosperm species belonging to 25 orders shows that epistomatal mucilage plugs are a widespread phenomenon. Measurements of the leaf water status by using the leaf patch clamp pressure technique suggest that the mucilage plugs are involved in moisture uptake and buffering leaf cells against complete turgor pressure loss at low humidity.
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Affiliation(s)
- M Westhoff
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
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13
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Zimmermann D, Westhoff M, Zimmermann G, Gessner P, Gessner A, Wegner LH, Rokitta M, Ache P, Schneider H, Vásquez JA, Kruck W, Shirley S, Jakob P, Hedrich R, Bentrup FW, Bamberg E, Zimmermann U. Foliar water supply of tall trees: evidence for mucilage-facilitated moisture uptake from the atmosphere and the impact on pressure bomb measurements. PROTOPLASMA 2008; 232:11-34. [PMID: 18176835 DOI: 10.1007/s00709-007-0279-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 06/05/2007] [Indexed: 05/25/2023]
Abstract
The water supply to leaves of 25 to 60 m tall trees (including high-salinity-tolerant ones) was studied. The filling status of the xylem vessels was determined by xylem sap extraction (using jet-discharge, gravity-discharge, and centrifugation) and by (1)H nuclear magnetic resonance imaging of wood pieces. Simultaneously, pressure bomb experiments were performed along the entire trunk of the trees up to a height of 57 m. Clear-cut evidence was found that the balancing pressure (P(b)) values of leafy twigs were dictated by the ambient relative humidity rather than by height. Refilling of xylem vessels of apical leaves (branches) obviously mainly occurred via moisture uptake from the atmosphere. These findings could be traced back to the hydration and rehydration of mucilage layers on the leaf surfaces and/or of epistomatal mucilage plugs. Xylem vessels also contained mucilage. Mucilage formation was apparently enforced by water stress. The observed mucilage-based foliar water uptake and humidity dependency of the P(b) values are at variance with the cohesion-tension theory and with the hypothesis that P(b) measurements yield information about the relationships between xylem pressure gradients and height.
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Affiliation(s)
- D Zimmermann
- Abteilung für Biophysikalische Chemie, Max-Planck-Institut für Biophysik, Frankfurt am Main, Federal Republic of Germany.
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14
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Sebastián JL, Muñoz S, Sancho M, Álvarez G, Miranda JM. Electric field distribution and energy absorption in anisotropic and dispersive red blood cells. Phys Med Biol 2007; 52:6831-47. [DOI: 10.1088/0031-9155/52/23/004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Albrecht DR, Underhill GH, Mendelson A, Bhatia SN. Multiphase electropatterning of cells and biomaterials. LAB ON A CHIP 2007; 7:702-9. [PMID: 17538711 DOI: 10.1039/b701306j] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Tissues formed by cells encapsulated in hydrogels have uses in biotechnology, cell-based assays, and tissue engineering. We have previously presented a 3D micropatterning technique that rapidly localizes live cells within hydrogels using dielectrophoretic (DEP) forces, and have demonstrated the ability to modulate tissue function through the control of microscale cell architecture. A limitation of this method is the requirement that a single biomaterial must simultaneously harbor biological properties that support cell survival and function and material properties that permit efficient dielectrophoretic patterning. Here, we resolve this issue by forming multiphase tissues consisting of microscale tissue sub-units in a 'local phase' biomaterial, which, in turn, are organized by DEP forces in a separate, mechanically supportive 'bulk phase' material. We first define the effects of medium conductivity on the speed and quality of DEP cell patterning. As a case study, we then produce multiphase tissues with microscale architecture that combine high local hydrogel conductivity for enhanced survival of sensitive liver progenitor cells with low bulk conductivity required for efficient DEP micropatterning. This approach enables an expanded range of studies examining the influence of 3D cellular architecture on diverse cell types, and in the future may improve the biological function of inhomogeneous tissues assembled from a variety of modular tissue sub-units.
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Affiliation(s)
- Dirk R Albrecht
- Harvard-M.I.T. Division of Health Sciences and Technology/Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., E19-502D, Cambridge, MA, USA
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Simeonova M, Gimsa J. The influence of the molecular structure of lipid membranes on the electric field distribution and energy absorption. Bioelectromagnetics 2006; 27:652-66. [PMID: 16917873 DOI: 10.1002/bem.20259] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We consider the influence of the molecular structure of phospholipid membranes on their dielectric properties in the radio frequency range. Membranes have a stratified dielectric structure on the submolecular level, with the lipid chains forming a central hydrophobic layer enclosed by the polar headgroups (HGs) and bound water layers. In our numerical model, isotropic permittivities of 2.2 and 48.8 were assigned to the lipid chain and bound water layers, respectively. The HG region was assumed to possess an anisotropic static permittivity with 142.2 and 30.2 in the tangential and normal directions, respectively. The permittivities of the HG and bound water regions have been assumed to disperse at frequencies around 51 and 345 MHz to become 2.2 and 1.8, respectively, in both the normal and tangential directions. Electric field distribution and absorption were calculated for phospholipid vesicles with 75 nm radius as an example. Significant absorption has been obtained in the HG and bound water regions. Averaging the membrane absorption over the layers resulted in a decreased absorption below 1 GHz but a more than 10-fold increase above 1 GHz, compared to a model with a homogeneous membrane of averaged properties. We propose single particle dielectric spectroscopy by AC electrokinetics at low-bulk medium conductivities for an experimental verification of our model.
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Affiliation(s)
- Margarita Simeonova
- Department of Biology, University of Rostock, Chair of Biophysics, Rostock, Germany
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17
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Zimmermann H, Zimmermann D, Reuss R, Feilen PJ, Manz B, Katsen A, Weber M, Ihmig FR, Ehrhart F, Gessner P, Behringer M, Steinbach A, Wegner LH, Sukhorukov VL, Vásquez JA, Schneider S, Weber MM, Volke F, Wolf R, Zimmermann U. Towards a medically approved technology for alginate-based microcapsules allowing long-term immunoisolated transplantation. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2005; 16:491-501. [PMID: 15928863 DOI: 10.1007/s10856-005-0523-2] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2004] [Accepted: 10/15/2004] [Indexed: 05/02/2023]
Abstract
The concept of encapsulated-cell therapy is very appealing, but in practice a great deal of technology and know-how is needed for the production of long-term functional transplants. Alginate is one of the most promising biomaterials for immunoisolation of allogeneic and xenogeneic cells and tissues (such as Langerhans islets). Although great advances in alginate-based cell encapsulation have been reported, several improvements need to be made before routine clinical applications can be considered. Among these is the production of purified alginates with consistently high transplantation-grade quality. This depends to a great extent on the purity of the input algal source as well as on the development of alginate extraction and purification processes that can be validated. A key engineering challenge in designing immunoisolating alginate-based microcapsules is that of maintaining unimpeded exchange of nutrients, oxygen and therapeutic factors (released by the encapsulated cells), while simultaneously avoiding swelling and subsequent rupture of the microcapsules. This requires the development of efficient, validated and well-documented technology for cross-linking alginates with divalent cations. Clinical applications also require validated technology for long-term cryopreservation of encapsulated cells to maintaining a product inventory in order to meet end-user demands. As shown here these demands could be met by the development of novel, validated technologies for production of transplantation-grade alginate and microcapsule engineering and storage. The advances in alginate-based therapy are demonstrated by transplantation of encapsulated rat and human islet grafts that functioned properly for about 1 year in diabetic mice.
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Affiliation(s)
- H Zimmermann
- Abteilung Kryobiophysik & Kryotechnologie, Fraunhofer-Institut für Biomedizinische Technik, 66386, St. Ingbert, Germany
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18
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Zimmermann H, Hillgärtner M, Manz B, Feilen P, Brunnenmeier F, Leinfelder U, Weber M, Cramer H, Schneider S, Hendrich C, Volke F, Zimmermann U. Fabrication of homogeneously cross-linked, functional alginate microcapsules validated by NMR-, CLSM- and AFM-imaging. Biomaterials 2003; 24:2083-96. [PMID: 12628829 DOI: 10.1016/s0142-9612(02)00639-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cross-linked alginate microcapsules of sufficient mechanical strength can immunoisolate cells for the long-term treatment of hormone and other deficiency diseases in human beings. However, gelation of alginate by external Ba(2+) (or other divalent cations) produces non-homogeneous cross-linking of the polymeric mannuronic (M) and guluronic (G) acid chains. The stability of such microcapsules is rather limited. Here, we show that homogeneous cross-linking can be achieved by injecting BaCl(2) crystals into alginate droplets before they come into contact with external BaCl(2). The high effectiveness of this crystal gun method is demonstrated by confocal laser scanning microscopy and by advanced nuclear magnetic resonance imaging. Both techniques gave clear-cut evidence that homogeneous cross-linkage throughout the microcapsule is only obtained with simultaneous internal and external gelation. Atomic force microscopy showed a very smooth surface topography for microcapsules made by the crystal gun method, provided that excess Ba(2+) ions were removed immediately after gelation. In vitro experiments showed greatly suppressed swelling for crystal gun microcapsules. Even alginate extracted from Lessonia nigrescens (highly biocompatible) yielded microcapsules with long-term mechanical stability not hitherto possible. Encapsulation of rat islets, human monoclonal antibodies secreting hybridoma cells and murine mesenchymal stem cells transfected with cDNA encoding for bone morphogenetic protein (BMP-4) revealed that injection of BaCl(2) crystals has no adverse side effects on cell viability and function. However, the release of low-molecular weight factors (such as insulin) may be delayed when using alginate concentrations in the usual range.
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Affiliation(s)
- H Zimmermann
- Arbeitsgruppe Tieftemperatur-Biophysik, Fraunhofer Institut für Biomedizinische Technik (IBMT), 66386, St. Ingbert, Germany
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Weber M, Steinert A, Jork A, Dimmler A, Thürmer F, Schütze N, Hendrich C, Zimmerman U. Formation of cartilage matrix proteins by BMP-transfected murine mesenchymal stem cells encapsulated in a novel class of alginates. Biomaterials 2002; 23:2003-13. [PMID: 11996042 DOI: 10.1016/s0142-9612(01)00329-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proliferation and differentiation of wild-type, BMP-2 and BMP-4 transfected cells of C3H10T1/2, a mouse mesenchymal stem cell line that can differentiate into chondrocytes, were studied under monolayer (2D-) and encapsulation (3D-) conditions. Cells were encapsulated in a novel class of alginate. The alginate was of clinical grade (CG) because of complete removal of mitogenic and cytotoxic contaminants by chemical means. Compared to commercial alginates used so far for encapsulation it was characterized by ultra-high viscosity (UHV; viscosity of a 0.1% w/v solution of about 20 cP). In contrast to monolayer cultures, proliferation of cells was prevented when the cells were encapsulated in UHV/CG alginate at the same suspension density. As revealed by immunohistochemistry and quantitative RT-PCR, transfected and wild-type monolayer cells showed synthesis of type I collagen after transfer into differentiation medium, while culture in an alginate scaffold resulted in an upregulation of type II collagen and other hyaline cartilage proteins. BMP-4 transfected cells produced considerably more type II collagen than BMP-2 transfected and wild-type cells. BMP-4 transfected cells were also characterized by type I collagen production up to Day 10 and exhibited transient alkaline phosphatase activity levels that were much higher than the peak values observed for the other two cell lines. The coincidence of the ALP peak values with downregulation of type I collagen in BMP-4 transfected cells suggested that C3H10T1/2 cells differentiate into chondrocytes via a chondroprogenitor-like cell.
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Affiliation(s)
- M Weber
- Department of Biotechnology, University of Würzburg, Am Hubland, Biozentrum, Germany
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20
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Zimmermann U, Thürmer F, Jork A, Weber M, Mimietz S, Hillgärtner M, Brunnenmeier F, Zimmermann H, Westphal I, Fuhr G, Nöth U, Haase A, Steinert A, Hendrich C. A novel class of amitogenic alginate microcapsules for long-term immunoisolated transplantation. Ann N Y Acad Sci 2001; 944:199-215. [PMID: 11797670 DOI: 10.1111/j.1749-6632.2001.tb03833.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the light of results of clinical trials with immunoisolated human parathyroid tissue Ba2+-alginate capsules were developed that meet the requirements for long-term immunoisolated transplantation of (allogeneic and xenogeneic) cells and tissue fragments. Biocompatibility of the capsules was achieved by subjecting high-M alginate extracted from freshly collected brown algae to a simple purification protocol that removes quantitatively mitogenic and cytotoxic impurities without degradation of the alginate polymers. The final ultra-high-viscosity, clinical-grade (UHV/CG) product did not evoke any (significant) foreign body reaction in BB rats or in baboons. Similarly, the very sensitive pERK assay did not reveal any mitogenic impurities. Encapsulated cells also exhibited excellent secretory properties under in vitro conditions. Despite biocompatible material, pericapsular fibrosis is also induced by imperfect capsule surfaces that can favor cell attachment and migration under the release of material traces. This material can interact with free end monomers of the alginate polymers under formation of mitogenic advanced glycation products. Smooth surfaces, and thus topographical biocompatibility of the capsules (visualized by atomic force microscopy), can be generated by appropriate crosslinking of the UHV/CG-alginate with Ba2+ and simultaneous suppression of capsule swelling by incorporation of proteins and/or perfluorocarbons (i.e., medically approved compounds with high oxygen capacity). Perfluorocarbon-loaded alginate capsules allow long-term non-invasive monitoring of the location and the oxygen supply of the transplants by using 19F-MRI. Transplantation studies in rats demonstrated that these capsules were functional over a period of more than two years.
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Affiliation(s)
- U Zimmermann
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, Germany.
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21
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Sattelmacher B. The apoplast and its significance for plant mineral nutrition. THE NEW PHYTOLOGIST 2001; 149:167-192. [PMID: 33874640 DOI: 10.1046/j.1469-8137.2001.00034.x] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
It has only recently become apparent that the apoplast plays a major role in a diverse range of processes, including intercellular signalling, plant-microbe interactions and both water and nutrient transport. Broadly defined, the apoplast constitutes all compartments beyond the plasmalemma - the interfibrillar and intermicellar space of the cell walls, and the xylem, including its gas- and water-filled intercellular space - extending to the rhizoplane and cuticle of the outer plant surface. The physico-chemical properties of cell walls influence plant mineral nutrition, as nutrients do not simply pass through the apoplast to the plasmalemma but can also be adsorbed or fixed to cell-wall components. Here, current progress in understanding the significance of the apoplast in plant mineral nutrition is reviewed. The contribution of the root apoplast to short-distance transport and nutrient uptakes is examined particularly in relation to Na+ toxicity and Al3+ tolerance. The review extends to long-distance transport and the role of the apoplast as a habitat for microorganisms. In the leaf, the apoplast might have benefits over the vacuole as a site for short-term nutrient storage and solute exchange with the atmosphere. Contents Summary 167 I. Introduction 168 II. The properties of the apoplast and its implication for solute movement 168 1. The middle lamella 168 2. The primary wall 168 3. The secondary cell wall 169 III. The root apoplast - nutrient uptake and short-distance transport 170 IV. The apoplast as a compartment for long distance transport 174 V. The apoplast - habitat for microorganisms 175 VI. The apoplast of leaves - a compartment of storage and of reactions 177 1. Transport routes in the leaf apoplast 177 2. Methods of studying apoplastic solutes 177 3. Solute relations in the leaf apoplast 178 4. Concentration gradients in the leaf apoplast 179 5. Ion relations in the leaf apoplast and symptoms of deficiency and toxicity 179 6. Ion relations in the leaf apoplast - influence of nutrient supply 180 7. The leaf apoplast - compartment for transient ion storage 180 8. Ion fluxes between apoplast and symplast 181 9. Apoplastic ion balance 181 10. Leaf apoplast - interaction with the atmosphere 183 VII. Conclusions 183 Acknowledgements 183 References 183.
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Affiliation(s)
- Burkhard Sattelmacher
- Institute for Plant Nutrition and Soil Science, University Kiel, Oshausenstr. 40 D-24118 Kiel, Germany
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Nöth U, Gröhn P, Jork A, Zimmermann U, Haase A, Lutz J. 19F-MRI in vivo determination of the partial oxygen pressure in perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity and different tissues. Magn Reson Med 1999; 42:1039-47. [PMID: 10571925 DOI: 10.1002/(sici)1522-2594(199912)42:6<1039::aid-mrm8>3.0.co;2-n] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Semipermeable hydrogels formed with a biocompatible alginate solution and Ba(2+) ions protect encapsulated cells and tissues from a foreign immune system. For the viability and metabolic activity of the encapsulated materials, a sufficient oxygen supply inside the capsules is necessary. Quantitative (19)F-MRI was performed on perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity, the musculus quadriceps femoris, and beneath the kidney capsule of rats, in order to determine in vivo the partial oxygen pressure (pO(2)) inside the capsules at these implantation sites. The temporal behavior of the pO(2) values was observed for at least 3 months. The most stable values over time were observed in the kidney, where inter-rat pO(2) differences were considerable. In the muscle, the values were very high directly after implantation and decreased to nearly zero after 2 weeks. In the peritoneal cavity, values changed randomly over a wide range between different rats and over time. Magn Reson Med 42:1039-1047, 1999.
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Affiliation(s)
- U Nöth
- Physikalisches Institut, Lehrstuhl für Biophysik, Am Hubland, Würzburg, Germany
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