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Publications (5 of 5) Show all publications
Al-Farsi, H. M., Al-Adwani, S., Ahmed, S., Vogt, C., Ambikan, A. T., Leber, A., . . . Bergman, P. (2019). Effects of the Antimicrobial Peptide LL-37 and Innate Effector Mechanisms in Colistin-Resistant Klebsiella pneumoniae With mgrB Insertions. Frontiers in Microbiology, 10, Article ID 2632.
Open this publication in new window or tab >>Effects of the Antimicrobial Peptide LL-37 and Innate Effector Mechanisms in Colistin-Resistant Klebsiella pneumoniae With mgrB Insertions
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2019 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 10, article id 2632Article in journal (Refereed) Published
Abstract [en]

Background Colistin is a polypeptide antibiotic drug that targets lipopolysaccharides in the outer membrane of Gram-negative bacteria. Inactivation of the mgrB-gene is a common mechanism behind colistin-resistance in Klebsiella pneumoniae (Kpn). Since colistin is a cyclic polypeptide, it may exhibit cross-resistance with the antimicrobial peptide LL-37, and with other innate effector mechanisms, but previous results are inconclusive. Objective To study potential cross-resistance between colistin and LL-37, as well as with other innate effector mechanisms, and to compare virulence of colistin-resistant and susceptible Kpn strains. Materials/Methods Carbapenemase-producing Kpn from Oman (n = 17) were subjected to antimicrobial susceptibility testing and whole genome sequencing. Susceptibility to colistin and LL-37 was studied. The surface charge was determined by zeta-potential measurements and the morphology of treated bacteria was analyzed with electron microscopy. Bacterial survival was assessed in human whole blood and serum, as well as in a zebrafish infection-model. Results Genome-analysis revealed insertion-sequences in the mgrB gene, as a cause of colistin resistance in 8/17 isolates. Colistin-resistant (Col-R) isolates were found to be more resistant to LL-37 compared to colistin-susceptible (Col-S) isolates, but only at concentrations >= 50 mu g/ml. There was no significant difference in surface charge between the isolates. The morphological changes were similar in both Col-R and Col-S isolates after exposure to LL-37. Finally, no survival difference between the Col-R and Col-S isolates was observed in whole blood or serum, or in zebrafish embryos. Conclusion Cross-resistance between colistin and LL-37 was observed at elevated concentrations of LL-37. However, Col-R and Col-S isolates exhibited similar survival in serum and whole blood, and in a zebrafish infection-model, suggesting that cross-resistance most likely play a limited role during physiological conditions. However, it cannot be ruled out that the observed cross-resistance could be relevant in conditions where LL-37 levels reach high concentrations, such as during infection or inflammation.

Place, publisher, year, edition, pages
FRONTIERS MEDIA SA, 2019
Keywords
cross-resistance, colistin, LL-37, innate immunity, zeta potential, whole blood killing assay, serum killing assay, zebrafish
National Category
Clinical Medicine
Identifiers
urn:nbn:se:kth:diva-266309 (URN)10.3389/fmicb.2019.02632 (DOI)000501260900001 ()31803163 (PubMedID)2-s2.0-85076028573 (Scopus ID)
Note

QC 20200107

Available from: 2020-01-07 Created: 2020-01-07 Last updated: 2020-01-09Bibliographically approved
Li, Y., Shaker, K., Larsson, J. C., Vogt, C., Hertz, H. M. & Toprak, M. S. (2018). A Library of Potential Nanoparticle Contrast Agents for X-Ray Fluorescence Tomography Bioimaging. Contrast Media & Molecular Imaging, Article ID UNSP 8174820.
Open this publication in new window or tab >>A Library of Potential Nanoparticle Contrast Agents for X-Ray Fluorescence Tomography Bioimaging
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2018 (English)In: Contrast Media & Molecular Imaging, ISSN 1555-4309, E-ISSN 1555-4317, article id UNSP 8174820Article in journal (Refereed) Published
Abstract [en]

Nanoparticles (NPs) have been used as contrast agents for several bioimaging modalities. X-ray fluorescence (XRF) tomography can provide sensitive and quantitative 3D detection of NPs. With spectrally matched NPs as contrast agents, we demonstrated earlier in a laboratory system that XRF tomography could achieve high-spatial-resolution tumor imaging in mice. Here, we present the synthesis, characterization, and evaluation of a library of NPs containing Y, Zr, Nb, Rh, and Ru that have spectrally matched K-shell absorption for the laboratory scale X-ray source. The K-shell emissions of these NPs are spectrally well separated from the X-ray probe and the Compton background, making them suitable for the lab-scale XRF tomography system. Their potential as XRF contrast agents is demonstrated successfully in a small-animal equivalent phantom, confirming the simulation results. The diversity in the NP composition provides a flexible platform for a better design and biological optimization of XRF tomography nanoprobes.

Place, publisher, year, edition, pages
WILEY-HINDAWI, 2018
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-242269 (URN)10.1155/2018/8174820 (DOI)000455608200001 ()30686945 (PubMedID)2-s2.0-85059939967 (Scopus ID)
Note

QC 20190201

Available from: 2019-02-01 Created: 2019-02-01 Last updated: 2020-03-09Bibliographically approved
Mukherjee, S. P., Gliga, A. R., Lazzaretto, B., Brandner, B., Fielden, M., Vogt, C., . . . Fadeel, B. (2018). Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic. Nanoscale, 10(3), 1180-1188
Open this publication in new window or tab >>Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic
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2018 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 3, p. 1180-1188Article in journal (Refereed) Published
Abstract [en]

Neutrophils were previously shown to digest oxidized carbon nanotubes through a myeloperoxidase (MPO)-dependent mechanism, and graphene oxide (GO) was found to undergo degradation when incubated with purified MPO, but there are no studies to date showing degradation of GO by neutrophils. Here we produced endotoxin-free GO by a modified Hummers' method and asked whether primary human neutrophils stimulated to produce neutrophil extracellular traps or activated to undergo degranulation are capable of digesting GO. Biodegradation was assessed using a range of techniques including Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and mass spectrometry. GO sheets of differing lateral dimensions were effectively degraded by neutrophils. As the degradation products could have toxicological implications, we also evaluated the impact of degraded GO on the bronchial epithelial cell line BEAS-2B. MPO-degraded GO was found to be non-cytotoxic and did not elicit any DNA damage. Taken together, these studies have shown that neutrophils can digest GO and that the biodegraded GO is non-toxic for human lung cells.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-222253 (URN)10.1039/c7nr03552g (DOI)000423259000033 ()29271441 (PubMedID)2-s2.0-85040917284 (Scopus ID)
Note

QC 20180205

Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2020-03-09Bibliographically approved
Larsson, J. C., Vogt, C., Vågberg, W., Toprak, M., Dzieran, J., Arsenian-Henriksson, M. & Hertz, H. (2018). High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles. Physics in Medicine and Biology, 63, 164001
Open this publication in new window or tab >>High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles
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2018 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 63, p. 164001-Article in journal (Refereed) Published
Abstract [en]

Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2018
Keywords
x-ray, x-ray fluorescence, tomography, nanoparticles
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-233331 (URN)10.1088/1361-6560/aad51e (DOI)000441712300001 ()30033936 (PubMedID)2-s2.0-85052501337 (Scopus ID)
Funder
Swedish Research CouncilWallenberg Foundations
Note

QC 20180828

Available from: 2018-08-15 Created: 2018-08-15 Last updated: 2020-03-09Bibliographically approved
Akan, R., Parfeniukas, K., Vogt, C., Toprak, M. S. & Vogt, U. (2018). Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures. RSC Advances, 8(23), 12628-12634
Open this publication in new window or tab >>Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures
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2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 23, p. 12628-12634Article in journal (Refereed) Published
Abstract [en]

Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures. 

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
Keywords
Aspect ratio, Charge injection, Hydrofluoric acid, Nanocatalysts, Nanostructures, Plate metal, Processing, Silica, Silicon, X ray diffraction, Etching solutions, Metal-assisted chemical etching, Processing temperature, Reaction chemistry, Reaction parameters, Silica dissolution, Silicon interface, Silicon nano structures, Etching
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-227483 (URN)10.1039/c8ra01627e (DOI)000429450000016 ()2-s2.0-85045188242 (Scopus ID)
Funder
Swedish Research Council
Note

Export Date: 9 May 2018; Article; CODEN: RSCAC; Correspondence Address: Vogt, U.; KTH Royal Institute of Technology, Department of Applied Physics, Biomedical and X-ray Physics, Albanova University CenterSweden; email: uvogt@kth.se; Funding details: VR, Vetenskapsrådet; Funding text: This work was supported by the Swedish Research Council. We thank Adem B. Ergul for help with the cross-section images and Jussi Rahomäki for starting with MACE in our group. QC 20180516

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2020-02-19Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3095-0608

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