| 1. |
- Kehoe, Laura, et al.
(author)
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Make EU trade with Brazil sustainable
- 2019
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Journal article (other academic/artistic)
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| 2. |
- Gomez-Carretero, S., et al.
(author)
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Correction: Redox-active conducting polymers modulate Salmonella biofilm formation by controlling availability of electron acceptors (vol 3, article number 19, 2017)
- 2018
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In: npj Biofilms and Microbiomes. - : Nature Publishing Group. - 2055-5008. ; 4:1
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Journal article (other academic/artistic)abstract
- In the original published article, the author list did not include Karl Svennersten, Kristin Persson, Edwin Jager and Magnus Berggren. After publication, we were notified by the corresponding author that the author list did not accurately reflect the contributions made, and these authors have been added to the author list. The original “Author Contributions” stated that “S.G.C., M.R., and A.R.D. designed research; S.G.C. performed all experiments…” this has been updated to read “S.G.C., K.S., K.M.P., E.W.H.J., M.B., M.R., and A.R.D. designed research; K.S., K.M.P., and E.W.H.J. performed experiments; S.G.C. performed all reported experiments…”. The “Acknowledgements” previously read “We thank K. Svennersten, A. Kader, K. Persson, and M. Berggren for fruitful discussions, and S. Löffler for insightful comments on the manuscript…” and have been updated to state “We thank A. Kader for fruitful discussions and S. Loffler for insightful comments on the manuscript…”. The “Competing Interests” section did not require any amendments. All authors have agreed with this correction statement and authorship change.
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| 3. |
- Gomez-Carretero, S., et al.
(author)
-
Redox-active conducting polymers modulate Salmonella biofilm formation by controlling availability of electron acceptors (vol 3, article number 19, 2017)
- 2017
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In: npj Biofilms and Microbiomes. - : Springer Science and Business Media LLC. - 2055-5008. ; 3
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Journal article (peer-reviewed)abstract
- Biofouling is a major problem caused by bacteria colonizing abiotic surfaces, such as medical devices. Biofilms are formed as the bacterial metabolism adapts to an attached growth state. We studied whether bacterial metabolism, hence biofilm formation, can be modulated in electrochemically active surfaces using the conducting conjugated polymer poly(3,4-ethylenedioxythiophene) (PEDOT). We fabricated composites of PEDOT doped with either heparin, dodecyl benzene sulfonate or chloride, and identified the fabrication parameters so that the electrochemical redox state is the main distinct factor influencing biofilm growth. PEDOT surfaces fitted into a custom-designed culturing device allowed for redox switching in Salmonella cultures, leading to oxidized or reduced electrodes. Similarly large biofilm growth was found on the oxidized anodes and on conventional polyester. In contrast, biofilm was significantly decreased (52-58%) on the reduced cathodes. Quantification of electrochromism in unswitched conducting polymer surfaces revealed a bacteria-driven electrochemical reduction of PEDOT. As a result, unswitched PEDOT acquired an analogous electrochemical state to the externally reduced cathode, explaining the similarly decreased biofilm growth on reduced cathodes and unswitched surfaces. Collectively, our findings reveal two opposing effects affecting biofilm formation. While the oxidized PEDOT anode constitutes a renewable electron sink that promotes biofilm growth, reduction of PEDOT by a power source or by bacteria largely suppresses biofilm formation. Modulating bacterial metabolism using the redox state of electroactive surfaces constitutes an unexplored method with applications spanning from antifouling coatings and microbial fuel cells to the study of the role of bacterial respiration during infection.
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| 4. |
- Gomez-Carretero, Salvador, et al.
(author)
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Salmonella Biofilm Modulation with Electrically Conducting Polymers
- 2014
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Other publication (other academic/artistic)abstract
- Biofilms are ubiquitous in many human activities, constituting a threat or an advantage depending on the context of application. It is therefore of great interest to obtain new materials to study and control how biofilms are formed. Here, heparin and DBS (dodecylbenzenesulfonate) are incorporated as counter-ions to the PEDOT (poly(3,4-ethylenedioxythiophene)) backbone, forming conducting polymer thin-films. Polymer synthesis is based on electrodeposition, allowing for the adjustment, during fabrication, of properties like charge and hydrophobicity, important in bacterial adhesion. The electrochemical redox state of the polymer is of fundamental importance in Salmonella enterica Serovar Typhimurium biofilm modulation. Oxidized composites show increased levels of biofilm growth compared to reduced and pristine polymer films. As a result, biofilm formation is modulated by the application of a low electric voltage. Moreover, biofilm morphology and topology are affected by both the electrochemical redox state and the incorporated counter-ion, making these materials a useful tool in biofilm engineering.
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| 5. |
- Herland, Anna, et al.
(author)
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Electrochemical Control of Growth Factor Presentation To Steer Neural Stem Cell Differentiation
- 2011
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In: Angewandte Chemie International Edition. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 50:52, s. 12529-12533
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Journal article (peer-reviewed)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. |
- Olsén, Arne, et al.
(author)
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Identification of two protein-binding and functional regions of curli, a surface organelle and virulence determinant of Escherichia coli
- 2002
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In: Journal of Biological Chemistry. - 1083-351X. ; 277:37, s. 34568-34572
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Journal article (peer-reviewed)abstract
- Curli are surface organelles of Escherichia coli. These fibrous proteins, formed by polymerization of a 15-kDa subunit, are expressed by E. coli strains associated with severe infections in humans. A remarkable property of curli is their ability to interact with a wide range of human proteins, interactions that contribute to the enhanced virulence of curli-expressing E. coli. To define the protein-binding region(s) of curli, we investigated the binding properties of overlapping synthetic peptides covering the curli subunit. Two peptides, one covering a 24-amino acid residue sequence in the NH2-terminal half of the subunit (NNS24) and one corresponding to the 26 COOH-terminal residues (VDQ26), were found to bind a number of human proteins. Physiochemical analysis revealed that NNS24 adopts a thermally stable beta-structure, and in solution the peptide forms soluble multimers, predominantly octamers. Intact curli are known to activate the proinflammatory and procoagulant contact system, and when added to human plasma, the NNS24 and VDQ26 peptides induced the release of the potent vasoactive peptide bradykinin. The results map important curli functions to the regions corresponding to the NNS24 and VDQ26 sequences.
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| 7. |
- Persson, Kristin M, et al.
(author)
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Electronic control of cell detachment using a self-doped conducting polymer
- 2011
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In: Advanced Materials. - : Wiley-Blackwell. - 0935-9648 .- 1521-4095. ; 23:38, s. 4403-4408
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Journal article (peer-reviewed)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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| 8. |
- Persson, Kristin M, et al.
(author)
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Electronic control over detachment of a self-doped water-soluble conjugated polyelectrolyte
- 2014
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In: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 30:21, s. 6257-6266
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Journal article (peer-reviewed)abstract
- Water-soluble conducting polymers are of interest to enable more versatile processing in aqueous media as well as to facilitate interactions with biomolecules. Here, we report a substituted poly(3,4-ethylenedioxythiophene) derivative (PEDOT-S:H) that is fully water-soluble and self-doped. When electrochemically oxidizing a PEDOT-S:H thin film, the film detaches from the underlying electrode. The oxidation of PEDOT-S:H starts with an initial phase of swelling followed by cracking before it finally disrupts into small flakes and detaches from the electrode. We investigated the detachment mechanism and found that parameters such as the size, charge, and concentration of ions in the electrolyte, the temperature, and also the pH influence the characteristics of detachment. When oxidizing PEDOT-S:H, the positively charged polymer backbone is balanced by anions from the electrolyte solution and also by the sulfonate groups on the side chains (more self-doping). From our experiments, we conclude that detachment of the PEDOT-S:H film upon oxidation occurs in part due to swelling caused by an inflow of solvated anions and associated water and in part due to chain rearrangements within the film, caused by more self-doping. We believe that PEDOT-S:H detachment can be of interest in a number of different applications, including addressed and active control of the release of materials such as biomolecules and cell cultures. © 2014 American Chemical Society.
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| 9. |
- Persson, Kristin M, et al.
(author)
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Selective Detachment of Human Primary Keratinocytes and Fibroblasts Using an Addressable Conjugated Polymer Matrix
- 2014
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Other publication (other academic/artistic)abstract
- Conjugated polymers have been used in several applications for electronic control of cell cultures over the last years. We have shown detachment of human endothelial cells using a thin film of a self-doped water-soluble conjugated polymer. Upon electrochemical oxidation, the film swells, cracks and finally detaches taking cells cultured on top along with it. The polymer can be patterned using standard photolithography. The detachment only occurs above a threshold potential of +0.7 V and this fact has been used to create a simple actively addressed matrix, based on a resistor network placed in an encapsulated back plane. The matrix has individually detachable pixels. In this paper we have evaluated detachment of human primary keratinocytes and fibroblasts using PEDOT-S:H. In addition, we have studied effects of serum proteins, added as nutrients to the cell culture medium, on the detachment properties. It was found that at prolonged incubation times protein adhesion effectively stopped the detachment. Using shorter incubation times before detachment, both keratinocytes and fibroblasts can be detached using a regular planar device as well as the matrix device for selective detachment. Spatial control of detachment could be of use when selecting cells for clonal expansion and in order to obtain a homogeneous starting population of cells aimed for tissue engineering purposes.
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