| 1. |
- Backe, Carin, et al.
(författare)
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Serially connected EAP based tape yarns for in-air actuation using textile structures
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Smart textiles that have the capability for actuation are of great interest for creating wearables and haptic devices. Through the use of textile fabric production processes electroactive polymeric materials in the form of film-based yarns can be integrated and combined with passive yarns to create soft, actuating fabrics. This way single EAP materials can be transformed into segments consisting of multiple EAP yarns working together. Furthermore, these segments can be positioned within a fabric to work individually or simultaneously in different patterns by use of incorporated conductive yarn paths. While the chase for additivity in force is a long-standing part of developing new actuator structures, so is the need for additivity in displacement motion. Here we construct an actuating textile fabric through the process of weaving that is able to operate in-air using polypyrrole-based tape yarns with choline acetate ionic liquid. Finding the balance between the weaving parameters turned out to be key. We found that in a vertically suspended arrangement, a three-segment serially connected fabric assembly demonstrated an accumulative effect in displacement and a joint-like motion behaviour. This opens up for more complicated motion patterns to be created through textile processing of EAP materials.
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| 2. |
- Baumgartner, Johanna, et al.
(författare)
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Switchable presentation of cytokines on electroactive polypyrrole surfaces for hematopoietic stem and progenitor cells
- 2018
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Ingår i: Journal of Materials Chemistry B. - Cambridge : Royal Society of Chemistry. - 2050-750X .- 2050-7518. ; 6:28, s. 4665-4675
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Tidskriftsartikel (refereegranskat)abstract
- Hematopoietic stem cells are used in transplantations for patients with hematologic malignancies. Scarce sources require efficient strategies of expansion, including polymeric biomaterials mimicking architectures of bone marrow tissue. Tissue microenvironment and mode of cytokine presentation strongly influence cell fate. Although several cytokines with different functions as soluble or membrane-bound mediators have already been identified, their precise roles have not yet been clarified. A need exists for in vitro systems that mimic the in vivo situation to enable such studies. One way is to establish surfaces mimicking physiological presentation using protein-immobilization onto polymer films. However these films merely provide a static presentation of the immobilized proteins. It would be advantageous to also dynamically change protein presentation and functionality to better reflect the in vivo conditions. The electroactive polymer polypyrrole shows excellent biocompatibility and electrochemically alters its surface properties, becoming an interesting choice for such setups. Here, we present an in vitro system for switchable presentation of membrane-bound cytokines. We use interleukin IL-3, known to affect hematopoiesis, and show that when immobilized on polypyrrole films, IL-3 is bioavailable for the bone marrow-derived FDC-P1 progenitor cell line. Moreover, IL-3 presentation can be successfully altered by changing the redox state of the film, in turn influencing FDC-P1 cell viability. This novel in vitro system provides a valuable tool for stimuli-responsive switchable protein presentation allowing the dissection of relevant mediators in stem and progenitor cell behavior.
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| 3. |
- Cao, Danfeng, 1991-, et al.
(författare)
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Soft actuators that self-create bone for biohybrid (micro)robotics
- 2022
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Ingår i: Proceedings of The 5th International Conference on Manipulation, Automation, And Robotics at Small Scales (MARSS 2022). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665459730 - 9781665459747 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Here we present a new class of variable stiffness actuators for soft robotics based on biohybrid materials that change their state from soft-to-hard by creating their own bones. The biohybrid variable stiffness soft actuators were fabricated by combining the electromechanically active polymer polypyrrole (PPy) with a soft substrate of polydimethylsiloxane or alginate gel. These actuators were functionalized with cell-derived plasma membrane nanofragments (PMNFs), which promote rapid mineralization within 2 days. These actuators were used in robotic devices, and PMNF mineralization resulted in the robotic devices to achieve a soft to stiff state change and thereby a decreased or stopped actuation. Moreover, perpendicularly and diagonally patterned actuators were prepared. The patterned actuators showed programmed directional actuation motion and could be fixated in this programmed state. Finally, patterned actuators that combined soft and rigid parts in one actuator showed more complex actuation motion. Together, these variable stiffness actuators could expand the range of applications of morphing robotics with more complex structures and functions.
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| 4. |
- Guan, Na N., et al.
(författare)
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The role of ATP signalling in response to mechanical stimulation studied in T24 cells using new microphysiological tools
- 2018
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Ingår i: Journal of Cellular and Molecular Medicine (Print). - : Wiley. - 1582-1838 .- 1582-4934. ; 22:4, s. 2319-2328
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Tidskriftsartikel (refereegranskat)abstract
- The capacity to store urine and initiate voiding is a valued characteristic of the human urinary bladder. To maintain this feature, it is necessary that the bladder can sense when it is full and when it is time to void. The bladder has a specialized epithelium called urothelium that is believed to be important for its sensory function. It has been suggested that autocrine ATP signalling contributes to this sensory function of the urothelium. There is well‐established evidence that ATP is released via vesicular exocytosis as well as by pannexin hemichannels upon mechanical stimulation. However, there are still many details that need elucidation and therefore there is a need for the development of new tools to further explore this fascinating field. In this work, we use new microphysiological systems to study mechanostimulation at a cellular level: a mechanostimulation microchip and a silicone‐based cell stretcher. Using these tools, we show that ATP is released upon cell stretching and that extracellular ATP contributes to a major part of Ca2+ signalling induced by stretching in T24 cells. These results contribute to the increasing body of evidence for ATP signalling as an important component for the sensory function of urothelial cells. This encourages the development of drugs targeting P2 receptors to relieve suffering from overactive bladder disorder and incontinence.
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| 5. |
- Herland, Anna, et al.
(författare)
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Electrochemical Control of Growth Factor Presentation To Steer Neural Stem Cell Differentiation
- 2011
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Ingår i: Angewandte Chemie International Edition. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 50:52, s. 12529-12533
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Tidskriftsartikel (refereegranskat)abstract
- Graphical Abstract Let it grow: The conjugated polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was synthesized with heparin as the counterion to form a cell culture substrate. The surface of PEDOT:heparin in the neutral state associated biologically active growth factors (see picture). Electrochemical in situ oxidation of PEDOT during live cell culture decreased the bioavailability of the growth factor and created an exact onset of neural stem cell differentiation.
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| 6. |
- Huniade, Claude, 1996-, et al.
(författare)
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EMIm-OTf Ionogel Coated Fibres - Characterisation and Development, Aiming at Ionic Smart Textiles
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ions are prevalent within bioelectronics, as they are the main charge carriers in living systems. In contrast to electronic systems, ionic ones are closer to what can be found in our body; in muscles, neurons and nerves.Textiles are a much-used biomedical material, both in vivo and in vitro due to its membrane character, highly efficient area, softness, biocompatibility and biodegradability. Modifying the physicochemical properties of the core or the surface of textile has been reported a countless number of times, but still, its use in a bioelectrical context is limited.Fibres are the building blocks of textiles and what make textiles an architected class of material. Then ionically conductive fibres are of great interest.Here, we show the preparation of iono-conductive textile fibres through the (semi-)continuous dip-coating of ionogel on the cellulose-based viscose.Ionogels are composed of salts in liquid state and a 3-dimensional solid network, in our case an ionic liquid (IL), 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, commonly named EMIm OTf or EMIm Triflate, and a thiol acrylate network, allowing the mobility of the ions within or in/out of the gel. This specific combination is a first effort towards the development of ionic textile fibres and ionic smart textiles, as a variety of ILs with different cations and anions exists, potentially allowing a large number of different combinations.We investigate how the coating of this ionogel affects the mechanical properties as well as the conductivity in AC or DC arrangement and their relation to temperature and humidity. Also, the thermal stability and sensitivity of degradation of the fibre system is studied.Moreover, we introduce different textile structures, and potential applications directed to bioelectronics.
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| 7. |
- Huniade, Claude, 1996-, et al.
(författare)
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Investigating ionic liquid-based click-ionogels by thiol-ene photopolymerisation onto textile yarns/fibres
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Electronic textiles’ primordial component are the connections that allow a circuit to be formed. As for today, the catalogue of conductive yarns is expanded to highly conductive metals such as copper, silver and steel, or electroconductive plastics composed of conductive polymers and electroconductive fillers such as metal particles or carbon allotropes.Ionic liquids are also able to carry electrical charges, and their capacity to conduct electricity has yet to be investigated as a yarn component, e.g. an ion conducting coating.Here, we report on attempts to coat ionic liquid-based click-ionogel on fibres, using thiol-ene reactions with the help of a photobase generator.Ionogel precursors, composed of plurithiol precursors, acrylate monomers and a triflate ionic-liquid, are applied on yarn and then cured by UV irradiation, initiating the Michael reaction and creating the thiol-acrylate-triflate network around the yarn.The aim of the present study is to prepare and characterise yarns coated with such ionogels, while developing a continuous yarn coating process.Several different ionogel compositions and different yarn topologies are investigated, comparing their structure, electrical conductivity, mechanical properties, thermal stability, behaviour to chemical reagents, as well as the different surface tensions and interfacial interactions.Textile processability is explored by the manufacture of simple fabrics.An application for those ionic conductive coating is the ion supply for electroactive polymers coated yarns that currently rely on electrolytes. This novel coating will render the light-weight property of textile valuable, and therefore broadening their application as wearables.
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| 8. |
- Immerstrand, Charlotte, 1974-, et al.
(författare)
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Altered impedance during pigment aggregation in Xenopus laevis melanophores
- 2003
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Ingår i: Medical and Biological Engineering and Computing. - 0140-0118 .- 1741-0444. ; 41:3, s. 357-364
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Tidskriftsartikel (refereegranskat)abstract
- Melanophores are dark-brown pigment cells located in the skin of amphibia, fish and many invertebrates. The skin colour of these organisms is regulated by the translocation of pigment organelles, and the pigment distribution can be altered by external stimuli. The ability to change colour in response to stimuli makes these cells of interest for biosensing applications. It was investigated whether pigment aggregation in Xenopus laevis melanophores can be detected by impedance measurements performed in transparent microvials. The results show that cell attachment, cell spreading and pigment aggregation all resulted in impedance changes, seen particularly at the highest frequency tested (10 kHz). The mechanisms behind the impedance changes were investigated by the addition of latrunculin or melatonin, both of which cause pigment aggregation. The latrunculin-induced aggregation was associated with cell area decrease and filamentous actin (F-actin) breakdown, processes that can influence the impedance. Lack of F-actin breakdown and an increase in cell area during melatonin-induced aggregation suggest that some other intracellular process also contributes to the impedance decrease seen for melatonin. It was shown that impedance measurements reflect not only cell attachment and cell spreading, but also intracellular events.
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| 9. |
- Inganäs, Olle, et al.
(författare)
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Electrochemomechanical devices from polymer conductors and semiconductors
- 2001. - 2
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Ingår i: Encyclopedia of materials. - Oxford : Elsevier. - 9780080431529 ; , s. 2531-2535
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Conjugated polymer (CP) actuators are devices where the volume of a CP material is changed during a change of the state of oxidation or reduction of the polymer. The volume change is extracted as a geo-metrical change in uni- or bimorphs, where the active material may be combined with the passive supporting material. In bimorphs, which have an active layer supported on a passive Ælm, bending of the assembly occurs as the dimensional change is driven by electrochemistry.
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| 10. |
- Jager, Edwin W. H.
(författare)
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Conjugated Polymers as Actuators for Medical Devices and Microsystems
- 2010. - 1
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Ingår i: Iontronics. - Boca Raton : CRC Press; Taylor & Grancis Group. - 9781439806883 - 9781439806890 ; , s. 141-161
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Bokkapitel (refereegranskat)abstract
- In conducting polymers ion transport occurs during the (electro-)chemical oxidation and reduction of the polymer. This redox change results in a change of material properties such as conductivity, electrochromism, and wettability. The ion transport during this redox switching has also been used in drug release applications. This reversible intercalation motion of the ions also results in a volume change of conducting polymers. These materials were proposed as actuator materials by Baughman et al. for their large strains and low operating potentials. The first such conducting polymer-based actuator was demonstrated in the early 90’s by Pei and Inganäs. The phenomenon was thereafter demonstrated by other laboratories and the new field of conjugated polymer actuators emerged. Initial research was focused on understanding the physical principles behind the electrochemically induced actuation and exploring the limitations.
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| 11. |
- Jager, Edwin W. H., 1973-
(författare)
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Microsystems based on polypyrrole microactuators : microrobots and cell clinics
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Conducting polymers like polypyrrole (PPy) are suitable materials for actuators. PPy undergoes a volume change, driven by redox processes accompanied by ion movement. This volume change is reversible. By combining PPy with a support and/or electrode layer into a bilayer, actuators can be made. These actuators are operated in a liquid electrolyte. The microactuators presented in this thesis are based on an Au/PPy bilayer in which the Au acts both as a structural layer and electrode. PPy doped with DBS- ( dodecylbenzenesulfonate) anions (PPy(DBS)) is used and the microactuators are operated in an aqueous salt solution, usually NaDBS. However, the microactuators function also in other biological more relevant media, like blood plasma, urine, and cell culture media, making them excellent tools for cell biology and biomedicine. The thesis is focussed on methods to microfabricate devices, and their operation and use.PPy/Au microactuators, which have all the electrodes necessary for the actuation --the working, counter, and reference electrodes -- on-chip, were developed. The microactuators' performance was as good as when standard, off-chip counter and reference electrodes were used. Specifically, the speed of actuation was the same.A novel microfabrication method based on a Ti sacrificial layer was developed in order to create individually addressable and controllable polypyrrole-gold microactuators. Using these individually controlled microactuators, a micrometer-sized manipulator or microrobotic arm was fabricated. This microrobotic arm can pick up, lift, move, and place micrometer-sized objects within an area of about 250 x 100 μm2, making the microrobot an excellent tool for single cell manipulation. Also, these individually controlled microactuators were used to obtain movements both out of and in the plane of the substrate surface. A scheme to make true three-dimensional movements is demonstrated.Finally, the development of a cell clinic is presented. This is a micromachined cavity, or microvial, that can be closed with a lid. The lid is activated by two PPy/Au microactuators. A pair of Au electrodes was placed inside the microvials in order to perform impedance studies on single or a small number of cells. Impedance measurements on Xenopus leavis melanophores are reported. A change in the impedance upon cell spreading was measured and intracellular events such as the aggregation of pigment granules were identified. The electrical data are correlated to optical microscopy.
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| 12. |
- Jager, Edwin W.H., et al.
(författare)
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The cell clinic : closable microvials for single cell studies
- 2002
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Ingår i: Biomedical microdevices (Print). - 1387-2176 .- 1572-8781. ; 4:3, s. 177-187
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Tidskriftsartikel (refereegranskat)abstract
- We present the development of a cell clinic. This is a micromachined cavity, or microvial, that can be closed with a lid. The lid is activated by two polypyrrole/Au microactuators. Inside the microvials two Au electrodes have been placed in order to perform impedance studies on single or a small number of cells. We report on impedance measurements on Xenopus leavis melanophores. We could measure a change in the impedance upon cell spreading and identify intracellular events such as the aggregation of pigment granules. The electrical data is correlated to optical microscopy.
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| 13. |
- Khaldi, Alexandre, 1982-, et al.
(författare)
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Patterning highly conducting conjugated polymer electrodes for soft and flexible microelectrochemical devices
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:17, s. 14978-14985
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for soft actuators in various biomedical applications in order to manipulate delicate objects such as cells and tissues. Soft actuators are able to adapt to any shape and limit the stress applied to delicate objects. Conjugated polymer actuators, especially in the so-called trilayer configuration, are interesting candidates for driving such micromanipulators. However, challenges involved in patterning the electrodes in a trilayer with individual contact have prevented further development of soft micromanipulators based on conjugated polymer actuators. To allow such patterning, two printing-based patterning techniques have been developed. First an oxidant layer is printed using either syringe-based printing or micro-contact printing, followed by vapor phase polymerization of the conjugated polymer. Sub-millimeter patterns with electronic conductivities of 800 Scm-1 are obtained. Next, laser ablation is used to cleanly cut the final device structures including the printed patterns, resulting in fingers with individually controllable digits and miniaturized hands. The methods presented in this paper will enable integration of patterned electrically active conjugated polymer layers in many types of complex 3-D structures.
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| 14. |
- Persson, Kristin M, et al.
(författare)
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Electronic control of cell detachment using a self-doped conducting polymer
- 2011
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Ingår i: Advanced Materials. - : Wiley-Blackwell. - 0935-9648 .- 1521-4095. ; 23:38, s. 4403-4408
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Tidskriftsartikel (refereegranskat)abstract
- An electronic detachment technology based on thin films of a poly(3,4-ethylene-dioxythiophene) derivative is evaluated for controlled release of human epithelial cells. When applying a potential of 1 V, the redox-responsive polymer films detach and disintegrate and at the same time release cells cultured on top in the absence of any enzymatic treatment with excellent preservation of membrane proteins and cell viability.
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| 15. |
- Simon, Daniel T, et al.
(författare)
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Organic electronics for precise delivery of neurotransmitters to modulate mammalian sensory function.
- 2009
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 8:9, s. 742-746
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Tidskriftsartikel (refereegranskat)abstract
- Significant advances have been made in the understanding of the pathophysiology, molecular targets and therapies for the treatment of a variety of nervous-system disorders. Particular therapies involve electrical sensing and stimulation of neural activity, and significant effort has therefore been devoted to the refinement of neural electrodes. However, direct electrical interfacing suffers from some inherent problems, such as the inability to discriminate amongst cell types. Thus, there is a need for novel devices to specifically interface nerve cells. Here, we demonstrate an organic electronic device capable of precisely delivering neurotransmitters in vitro and in vivo. In converting electronic addressing into delivery of neurotransmitters, the device mimics the nerve synapse. Using the peripheral auditory system, we show that out of a diverse population of cells, the device can selectively stimulate nerve cells responding to a specific neurotransmitter. This is achieved by precise electronic control of electrophoretic migration through a polymer film. This mechanism provides several sought-after features for regulation of cell signalling: exact dosage determination through electrochemical relationships, minimally disruptive delivery due to lack of fluid flow, and on-off switching. This technology has great potential as a therapeutic platform and could help accelerate the development of therapeutic strategies for nervous-system disorders.
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| 16. |
- Svennersten, Karl, et al.
(författare)
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Electrochemical modulation of epithelia formation using conducting polymers
- 2009
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 30:31, s. 6257-6264
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Tidskriftsartikel (refereegranskat)abstract
- Conducting polymers are soft, flexible materials, exhibiting material properties that can be reversibly changed by electrochemically altering the redox state. Surface chemistry is an important determinant for the molecular events of cell adhesion. Therefore, we analyzed whether the redox state of the conducting polymer PEDOT:Tosylate can be used to control epithelial cell adhesion and proliferation. A functionalized cell culture dish comprising two adjacent electrode surfaces was developed. Upon electronic addressing, reduced and oxidized surfaces are created within the same device. Simultaneous analysis of how a homogenous epithelial MDCK cell population responded to the electrodes revealed distinct surface-specific differences. Presentation of functional fibronectin on the reduced electrode promoted focal adhesion formation, involving αvβ3 integrin, cell proliferation, and ensuing formation of polarized monolayers. In contrast, the oxidized surface harbored only few cells with deranged morphology showing no indication of proliferation. This stems from the altered fibronectin conformation, induced by the different surface chemistry of the PEDOT:Tosylate electrode in the oxidized state. Our results demonstrate a novel use of PEDOT:Tosylate as a cell-hosting material in multiple-electrode systems, where cell adhesion and proliferation can be controlled by electrochemical modulation of surface properties.
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| 17. |
- Svennersten, Karl, et al.
(författare)
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Mechanical stimulation of epithelial cells using polypyrrole microactuators.
- 2011
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 11:19, s. 3287-3293
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Tidskriftsartikel (refereegranskat)abstract
- The importance of mechanotransduction for physiological systems is becoming increasingly recognized. The effect of mechanical stimulation is well studied in organs and tissues, for instance by using flexible tissue culture substrates that can be stretched by external means. However, on the cellular and subcellular level, dedicated technology to apply appropriate mechanical stimuli is limited. Here we report an organic electronic microactuator chip for mechanical stimulation of single cells. These chips are manufactured on silicon wafers using traditional microfabrication and photolithography techniques. The active unit of the chip consists of the electroactive polymer polypyrrole that expands upon the application of a low potential. The fact that polypyrrole can be activated in physiological electrolytes makes it well suited as the active material in a microactuator chip for biomedical applications. Renal epithelial cells, which are responsive to mechanical stimuli and relevant from a physiological perspective, are cultured on top of the microactuator chip. The cells exhibit good adhesion and spread along the surface of the chip. After culturing, individual cells are mechanically stimulated by electrical addressing of the microactuator chip and the response to this stimulation is monitored as an increase in intracellular Ca(2+). This Ca(2+) response is caused by an autocrine ATP signalling pathway associated with mechanical stimulation of the cells. In conclusion, the present work demonstrates a microactuator chip based on an organic conjugated polymer, for mechanical stimulation of biological systems at the cellular and sub-cellular level.
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| 18. |
- Vagin, Mikhail Yu., et al.
(författare)
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Water-processable polypyrrole microparticle modules for direct fabrication of hierarchical structured electrochemical interfaces
- 2016
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 190, s. 495-503
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchically structured materials (HSMs) are becoming increasingly important in catalysis, separation and energy applications due to their advantageous diffusion and flux properties. Here, we introduce a facile modular approach to fabricate HSMs with tailored functional conducting polypyrrole microparticles (PPyMP). The PPyMPs were fabricated with a calcium carbonate (CaCO3) template-assisted polymerization technique in aqueous media at room temperature, thus providing a new green chemistry for producing water-processable functional polymers. The sacrificial CaCO3 template guided the polymerization process to yield homogenous PPyMPs with a narrow size distribution. The porous nature of the CaCO3 further allows the incorporation of various organic and inorganic dopants such as an electrocatalyst and redox mediator for the fabrication of functional PPyMPs. Dawson-type polyoxometalate (POM) and methylene blue (MB) were chosen as the model electrocatalyst and electron mediator dopant, respectively. Hierarchically structured electrochemical interfaces were created simply by self-assembly of the functional PPyMPs. We demonstrate the versatility of this technique by creating two different hierarchical structured electrochemical interfaces: POM-PPyMPs for hydrogen peroxide electrocatalysis and MB-PPyMPs for mediated bioelectrocatalysis. We envision that the presented design concept could be extended to different conducting polymers doped with other functional organic and inorganic dopants to develop advanced electrochemical interfaces and to create high surface area electrodes for energy storage.
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