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Publications (10 of 78) Show all publications
Tran, B., Watts, S., Valentin, J. D. P., Raßmann, N., Papastavrou, G., Ramstedt, M. & Salentinig, S. (2024). pH-responsive virus-based colloidal crystals for advanced material platforms. Advanced Functional Materials
Open this publication in new window or tab >>pH-responsive virus-based colloidal crystals for advanced material platforms
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2024 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028Article in journal (Refereed) Epub ahead of print
Abstract [en]

Bacteriophages have a well-defined nanoscale size, shape, and surface chemistry, making them promising candidates for creating advanced biomaterials for applications including biocatalysis, drug delivery, and biosensing. This study demonstrates the self-assembly of the ≈29 nm diameter bacteriophage Qbeta (Qubevirus durum) with the synthetic polycation, poly [2-(methacryloyloxy)ethyl] trimethylammonium chloride (pMETAC), into compartmentalized colloidal crystals. The pH and the polymer chain length tune their self-assembly and the resulting structure, with the potential for further chemical modification or loading with bioactive molecules. Small angle X-ray scattering (SAXS), multi-angle dynamic light scattering (DLS), and atomic force microscopy (AFM) are used for studying the Qbeta self-assembly into the geometrically ordered aggregates. The suprastructures form at pH > 7.0 and disassemble at pH < 7.0. Zeta potential measurements and X-ray photoelectron spectroscopy (XPS) show pMETAC adsorption onto the negatively charged Qbeta surface. The colloidal crystal formation is achieved without chemically modifying the Qbeta surface. Additionally, the Qbeta/pMETAC suprastructures can be easily separated from the suspension as macroscopic aggregate, maintaining their activity. Their simple preparation allows for large-scale production of advanced materials in food and health science applications and nanotechnology. The insights from this study will further advance the tailored design and production of novel colloidal materials.

Place, publisher, year, edition, pages
John Wiley & Sons, 2024
Keywords
colloidal crystals, hybrid materials, nanostructured materials, self-assembly, virus
National Category
Materials Chemistry Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-224126 (URN)10.1002/adfm.202402257 (DOI)001208659000001 ()2-s2.0-85191537806 (Scopus ID)
Available from: 2024-05-14 Created: 2024-05-14 Last updated: 2024-05-14
Yunda, E., Phan Le, Q. N., Björn, E. & Ramstedt, M. (2023). Biochemical characterization and mercury methylation capacity of Geobacter sulfurreducens biofilms grown in media containing iron hydroxide or fumarate. Biofilm, 6, Article ID 100144.
Open this publication in new window or tab >>Biochemical characterization and mercury methylation capacity of Geobacter sulfurreducens biofilms grown in media containing iron hydroxide or fumarate
2023 (English)In: Biofilm, E-ISSN 2590-2075, Vol. 6, article id 100144Article in journal (Refereed) Published
Abstract [en]

Geobacter species are common in iron-rich environments and can contribute to formation of methylmercury (MeHg), a neurotoxic compound with high bioaccumulation potential formed as a result of bacterial and archaeal physiological activity. Geobacter sulfurreducens can utilize various electron acceptors for growth including iron hydroxides or fumarate. However, it remains poorly understood how the growth on these compounds affects physiological properties of bacterial cells in biofilms, including the capacity to produce MeHg. The purpose of this study was to determine changes in the biochemical composition of G. sulfurreducens during biofilm cultivation in media containing iron hydroxide or fumarate, and to quantify mercury (Hg) methylation capacity of the formed biofilms. Biofilms were characterized by Fourier-transform infrared spectroscopy in the attenuated total reflection mode (ATR-FTIR), Resonance Raman spectroscopy and confocal laser scanning microscopy. MeHg formation was quantified by mass spectrometry after incubation of biofilms with 100 nM Hg. The results of ATR-FTIR experiments showed that in presence of fumarate, G. sulfurreducens biofilm formation was accompanied by variation in content of the energy-reserve polymer glycogen over time, which could be cancelled by the addition of supplementary nutrients (yeast extract). In contrast, biofilms cultivated on Fe(III) hydroxide did not accumulate glycogen. The ATR-FTIR results further suggested that Fe(III) hydroxide surfaces bind cells via phosphate and carboxylate groups of bacteria that form complexes with iron. Furthermore, biofilms grown on Fe(III) hydroxide had higher fraction of oxidized cytochromes and produced two to three times less biomass compared to conditions with fumarate. Normalized to biofilm volume, the content of MeHg was similar in assays with biofilms grown on Fe(III) hydroxide and on fumarate (with yeast extract and without). These results suggest that G. sulfurreducens biofilms produce MeHg irrespectively from glycogen content and cytochrome redox state in the cells, and warrant further investigation of the mechanisms controlling this process.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Biochemistry and Molecular Biology Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-213182 (URN)10.1016/j.bioflm.2023.100144 (DOI)001061813000001 ()37583615 (PubMedID)2-s2.0-85169894143 (Scopus ID)
Funder
The Kempe Foundations, JCK-1917
Available from: 2023-08-22 Created: 2023-08-22 Last updated: 2023-09-20Bibliographically approved
Cant, D. J. H., Pei, Y., Shchukarev, A., Ramstedt, M., Marques, S. S., Segundo, M. A., . . . Minelli, C. (2023). Cryo-XPS for surface characterization of nanomedicines. Journal of Physical Chemistry A, 127(39), 8220-8227
Open this publication in new window or tab >>Cryo-XPS for surface characterization of nanomedicines
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2023 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 127, no 39, p. 8220-8227Article in journal (Refereed) Published
Abstract [en]

Nanoparticles used for medical applications commonly possess coatings or surface functionalities intended to provide specific behavior in vivo, for example, the use of PEG to provide stealth properties. Direct, quantitative measurement of the surface chemistry and composition of such systems in a hydrated environment has thus far not been demonstrated, yet such measurements are of great importance for the development of nanomedicine systems. Here we demonstrate the first use of cryo-XPS for the measurement of two PEG-functionalized nanomedicines: a polymeric drug delivery system and a lipid nanoparticle mRNA carrier. The observed differences between cryo-XPS and standard XPS measurements indicate the potential of cryo-XPS for providing quantitative measurements of such nanoparticle systems in hydrated conditions.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Analytical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-215315 (URN)10.1021/acs.jpca.3c03879 (DOI)001070270700001 ()37733882 (PubMedID)2-s2.0-85173556161 (Scopus ID)
Funder
EU, Horizon 2020, 825828
Available from: 2023-10-17 Created: 2023-10-17 Last updated: 2023-11-06Bibliographically approved
Yunda, E., Gutensohn, M., Ramstedt, M. & Björn, E. (2023). Methylmercury formation in biofilms of Geobacter sulfurreducens. Frontiers in Microbiology, 14, Article ID 1079000.
Open this publication in new window or tab >>Methylmercury formation in biofilms of Geobacter sulfurreducens
2023 (English)In: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 14, article id 1079000Article in journal (Refereed) Published
Abstract [en]

Introduction: Mercury (Hg) is a major environmental pollutant that accumulates in biota predominantly in the form of methylmercury (MeHg). Surface-associated microbial communities (biofilms) represent an important source of MeHg in natural aquatic systems. In this work, we report MeHg formation in biofilms of the iron-reducing bacterium Geobacter sulfurreducens.

Methods: Biofilms were prepared in media with varied nutrient load for 3, 5, or 7 days, and their structural properties were characterized using confocal laser scanning microscopy, cryo-scanning electron microscopy and Fourier-transform infrared spectroscopy.

Results: Biofilms cultivated for 3 days with vitamins in the medium had the highest surface coverage, and they also contained abundant extracellular matrix. Using 3 and 7-days-old biofilms, we demonstrate that G. sulfurreducens biofilms prepared in media with various nutrient load produce MeHg, of which a significant portion is released to the surrounding medium. The Hg methylation rate constant determined in 6-h assays in a low-nutrient assay medium with 3-days-old biofilms was 3.9 ± 2.0 ∙ 10−14  L ∙ cell−1 ∙ h−1, which is three to five times lower than the rates found in assays with planktonic cultures of G. sulfurreducens in this and previous studies. The fraction of MeHg of total Hg within the biofilms was, however, remarkably high (close to 50%), and medium/biofilm partitioning of inorganic Hg (Hg(II)) indicated low accumulation of Hg(II) in biofilms.

Discussion: These findings suggest a high Hg(II) methylation capacity of G. sulfurreducens biofilms and that Hg(II) transfer to the biofilm is the rate-limiting step for MeHg formation in this systems.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2023
Keywords
methylmercury, biofilms, Geobacter sulfurreducens, mercury methylation, methylation rate
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-204111 (URN)10.3389/fmicb.2023.1079000 (DOI)000920863400001 ()2-s2.0-85147124881 (Scopus ID)
Funder
The Kempe Foundations, JCK-1917
Available from: 2023-01-27 Created: 2023-01-27 Last updated: 2024-01-17Bibliographically approved
Ramstedt, M. & Shchukarev, A. (2023). XPS spectra from nucleobases, DNA, and RNA. Surface Science Spectra, 30(1), Article ID 014011.
Open this publication in new window or tab >>XPS spectra from nucleobases, DNA, and RNA
2023 (English)In: Surface Science Spectra, ISSN 1055-5269, E-ISSN 1520-8575, Vol. 30, no 1, article id 014011Article in journal (Refereed) Published
Abstract [en]

X-ray photoelectron spectroscopy was used to analyze commercially available powders of thymine, uracil, cytosine, guanine, adenine, as well as DNA isolated from salmon testes and RNA from torula yeast. The powders were pressed onto a sample holder and analyzed as received from the manufacturer. Survey spectra and high-resolution spectra of O 1s, N 1s, C 1s of all nucleobases are reported, including a small Na 1s contamination in cytosine. Spectra of DNA and RNA are also included for comparison. Furthermore, the presented data are compared with previously published results, as well as theoretical values, and differences are discussed.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2023
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-208283 (URN)10.1116/6.0002368 (DOI)000988472100001 ()2-s2.0-85159787197 (Scopus ID)
Available from: 2023-05-16 Created: 2023-05-16 Last updated: 2023-06-21Bibliographically approved
Nakao, R., Kobayashi, H., Iwabuchi, Y., Kawahara, K., Hirayama, S., Ramstedt, M., . . . Ohnishi, M. (2022). A highly immunogenic vaccine platform against encapsulated pathogens using chimeric probiotic Escherichia coli membrane vesicles. npj Vaccines, 7(1), Article ID 153.
Open this publication in new window or tab >>A highly immunogenic vaccine platform against encapsulated pathogens using chimeric probiotic Escherichia coli membrane vesicles
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2022 (English)In: npj Vaccines, E-ISSN 2059-0105, Vol. 7, no 1, article id 153Article in journal (Refereed) Published
Abstract [en]

Vaccines against infectious diseases should elicit potent and long-lasting immunity, ideally even in those with age-related decline in immune response. Here we report a rational polysaccharide vaccine platform using probiotic Escherichia coli-derived membrane vesicles (MVs). First, we constructed a probiotic E. coli clone harboring the genetic locus responsible for biogenesis of serotype 14 pneumococcal capsular polysaccharides (CPS14) as a model antigen. CPS14 was found to be polymerized and mainly localized on the outer membrane of the E. coli cells. The glycine-induced MVs displayed the exogenous CPS14 at high density on the outermost surface, on which the CPS14 moiety was covalently tethered to a lipid A-core oligosaccharide anchor. In in vivo immunization experiments, CPS14+MVs, but not a mixture of free CPS14 and empty MVs, strongly elicited IgG class-switch recombination with a Th1/Th2-balanced IgG subclass distribution without any adjuvant. In addition, CPS14+MVs were structurally stable with heat treatment and immunization with the heat-treated MVs-elicited CPS14-specific antibody responses in mouse serum to levels comparable to those of non-treated CPS14+MVs. Notably, the immunogenicity of CPS14+MVs was significantly stronger than those of two currently licensed vaccines against pneumococci. The CPS14+MV-elicited humoral immune responses persisted for 1 year in both blood and lung. Furthermore, the CPS14+MV vaccine was widely efficacious in mice of different ages. Even in aged mice, vaccination resulted in robust production of CPS14-specific IgG that bound to the pneumococcal cell surface. Taken together, the present probiotic E. coli MVs-based vaccine platform offers a promising, generalizable solution against encapsulated pathogens.

Place, publisher, year, edition, pages
Nature Publishing Group, 2022
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-201460 (URN)10.1038/s41541-022-00572-z (DOI)000888807700001 ()2-s2.0-85142614736 (Scopus ID)
Available from: 2022-12-06 Created: 2022-12-06 Last updated: 2023-09-05Bibliographically approved
Dardouri, M., Bettencourt, A., Martin, V., Carvalho, F. A., Colaço, B., Gama, A., . . . Ribeiro, I. A. C. (2022). Assuring the Biofunctionalization of Silicone Covalently Bonded to Rhamnolipids: Antibiofilm Activity and Biocompatibility. Pharmaceutics, 14(9), Article ID 1836.
Open this publication in new window or tab >>Assuring the Biofunctionalization of Silicone Covalently Bonded to Rhamnolipids: Antibiofilm Activity and Biocompatibility
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2022 (English)In: Pharmaceutics, ISSN 1999-4923, E-ISSN 1999-4923, Vol. 14, no 9, article id 1836Article in journal (Refereed) Published
Abstract [en]

Silicone-based medical devices composed of polydimethylsiloxane (PDMS) are widely used all over the human body (e.g., urinary stents and catheters, central venous catheters stents) with extreme clinical success. Nevertheless, their abiotic surfaces, being prone to microorganism colonization, are often involved in infection occurrence. Improving PDMS antimicrobial properties by surface functionalization with biosurfactants to prevent related infections has been the goal of different works, but studies that mimic the clinical use of these novel surfaces are missing. This work aims at the biofunctional assessment of PDMS functionalized with rhamnolipids (RLs), using translational tests that more closely mimic the clinical microenvironment. Rhamnolipids were covalently bonded to PDMS, and the obtained surfaces were characterized by contact angle modification assessment, ATR-FTIR analysis and atomic force microscopy imaging. Moreover, a parallel flow chamber was used to assess the Staphylococcus aureus antibiofilm activity of the obtained surfaces under dynamic conditions, and an in vitro characterization with human dermal fibroblast cells in both direct and indirect characterization assays, along with an in vivo subcutaneous implantation assay in the translational rabbit model, was performed. A 1.2 log reduction in S. aureus biofilm was observed after 24 h under flow dynamic conditions. Additionally, functionalized PDMS lessened cell adhesion upon direct contact, while supporting a cytocompatible profile, within an indirect assay. The adequacy of the biological response was further validated upon in vivo subcutaneous tissue implantation. An important step was taken towards biofunctional assessment of RLs-functionalized PDMS, reinforcing their suitability for medical device usage and infection prevention.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
rhamnolipids, PDMS, flow chamber, translational rabbit model, antimicrobial, biocompatible
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-199046 (URN)10.3390/pharmaceutics14091836 (DOI)000856970200001 ()36145584 (PubMedID)2-s2.0-85138626018 (Scopus ID)
Available from: 2022-09-01 Created: 2022-09-01 Last updated: 2023-03-24Bibliographically approved
Ramstedt, M. & Burmølle, M. (2022). Can multi-species biofilms defeat antimicrobial surfaces on medical devices?. Current Opinion in Biomedical Engineering, 22, Article ID 100370.
Open this publication in new window or tab >>Can multi-species biofilms defeat antimicrobial surfaces on medical devices?
2022 (English)In: Current Opinion in Biomedical Engineering, ISSN 2468-4511, Vol. 22, article id 100370Article in journal (Refereed) Published
Abstract [en]

Infections deriving from medical devices represent a critical problem in health care causing suffering for patients, prolonged medical care, as well as consuming both human and monetary resources. An attractive solution is physical or chemical surface modifications of devices rendering them antibacterial and/or antifouling. However, the testing of such surfaces and coatings faces a range of challenges where one important is the predictability of in vitro assays for the outcome in vivo and in clinic. In this short review, we discuss what we consider is a major obstacle for design and evaluation of antimicrobial surfaces: microbial interspecies interactions. We give examples from the urinary tract, airways and from the oral cavity of functional consequences of such interactions in microbial communities, their therapeutic application for treatment, and how multi-species biofilms may influence the successful outcome of antimicrobial or antifouling surfaces. Furthermore, we suggest a path forward for in vitro testing taking these complexities into account during research and development.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Multi-species biofilms, Colonization order, Microbial adaptation, Fungi, Bacteria, Antimicrobial, Antifouling
National Category
Microbiology
Identifiers
urn:nbn:se:umu:diva-192932 (URN)10.1016/j.cobme.2022.100370 (DOI)000789221900004 ()2-s2.0-85124816692 (Scopus ID)
Funder
Swedish Research Council, 2018- 03879
Available from: 2022-03-04 Created: 2022-03-04 Last updated: 2023-09-05Bibliographically approved
Ramstedt, M. & Shchukarev, A. (2022). Cryo-XPS spectra from bacterial reference strain Pseudomonas fluorescens DSM50090. Surface Science Spectra, 29(1), Article ID 014010.
Open this publication in new window or tab >>Cryo-XPS spectra from bacterial reference strain Pseudomonas fluorescens DSM50090
2022 (English)In: Surface Science Spectra, ISSN 1055-5269, E-ISSN 1520-8575, Vol. 29, no 1, article id 014010Article in journal (Refereed) Published
Abstract [en]

Cryogenic x-ray photoelectron spectroscopy was used to analyze the cell envelope of intact and hydrated Gram-negative bacteria of the species Pseudomonas fluorescens. We used a reference strain, DSM50090, from the German microbial culture collection, which we previously have suggested would function well as a reference strain for future XPS analyses of Gram-negative bacteria. Bacteria were grown on nutrient agar plates at room temperature, collected with a cultivation loop, and washed using phosphate buffered saline. An aliquot of the cell pellet was fast-frozen on the sample holder in the sample introduction chamber to a temperature of 103 K and kept frozen throughout the measurement. Survey spectra and high-resolution spectra of Na 1s, O 1s, N 1s, C 1s, Cl 2p, S 2p, and P 2p are reported. The spectra obtained from the analyzed cells represent a combined signal from O, N, C, and S atoms in proteins, lipids, and polysaccharides at the cell surface. Furthermore, signal from P, Na, K, and Cl atoms was present both originating from processes in the cell envelope and remnants from the wash buffer.

Place, publisher, year, edition, pages
AVS Science and Technology Society, 2022
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-193343 (URN)10.1116/6.0001575 (DOI)000780202400001 ()2-s2.0-85127307826 (Scopus ID)
Available from: 2022-03-28 Created: 2022-03-28 Last updated: 2023-03-24Bibliographically approved
Hou, J., Wang, L., Alm, M., Thomsen, P., Monsen, T., Ramstedt, M. & Burmølle, M. (2022). Enhanced Antibiotic Tolerance of an In Vitro Multispecies Uropathogen Biofilm Model, Useful for Studies of Catheter-Associated Urinary Tract Infections. Microorganisms, 10(6), Article ID 1207.
Open this publication in new window or tab >>Enhanced Antibiotic Tolerance of an In Vitro Multispecies Uropathogen Biofilm Model, Useful for Studies of Catheter-Associated Urinary Tract Infections
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2022 (English)In: Microorganisms, E-ISSN 2076-2607, Vol. 10, no 6, article id 1207Article in journal (Refereed) Published
Abstract [en]

Catheter-associated urinary tract infections (CAUTI) are a common clinical concern as they can lead to severe, persistent infections or bacteremia in long-term catheterized patients. This type of CAUTI is difficult to eradicate, as they are caused by multispecies biofilms that may have reduced susceptibility to antibiotics. Many new strategies to tackle CAUTI have been proposed in the past decade, including antibiotic combination treatments, surface modification and probiotic usage. However, those strategies were mainly assessed on mono- or dual-species biofilms that hardly represent the long-term CAUTI cases where, normally, 2–4 or even more species can be involved. We developed a four-species in vitro biofilm model on catheters involving clinical strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella oxytoca and Proteus mirabilis isolated from indwelling catheters. Interspecies interactions and responses to antibiotics were quantitatively assessed. Collaborative as well as competitive interactions were found among members in our model biofilm and those interactions affected the individual species&rsquo; abundances upon exposure to antibiotics as mono-, dual- or multispecies biofilms. Our study shows complex interactions between species during the assessment of CAUTI control strategies for biofilms and highlights the necessity of evaluating treatment and control regimes in a multispecies setting.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
biofilms, CAUTI, multispecies, infections, interactions, antibiotic tolerance
National Category
Microbiology Biomaterials Science
Research subject
Microbiology
Identifiers
urn:nbn:se:umu:diva-196515 (URN)10.3390/microorganisms10061207 (DOI)000815897800001 ()2-s2.0-85131859553 (Scopus ID)
Funder
Swedish Research Council, 2018‐03879
Available from: 2022-06-14 Created: 2022-06-14 Last updated: 2023-09-05Bibliographically approved
Projects
Creation of Safe Antibacterial Surfaces- Antivirulence Gallium Complexes in Solution and at Surfaces [2011-03504_VR]; Umeå Universitynon-infective urinary catheters [2015-00193_Vinnova]; Umeå UniversityBacterial synergies in medical-device-associated infection [2018-03879_VR]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2646-8501

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