| 1. |
- Braun, Gabriel A., et al.
(författare)
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Deuterium-Enhanced Raman Spectroscopy for Histidine pKa Determination in a pH-Responsive Hydrogel
- 2020
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495. ; 119:9, s. 1701-1705
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Tidskriftsartikel (refereegranskat)abstract
- We report here a method for the determination of the pKa of histidine in complex or heterogeneous systems amenable to neither solid-state nor solution NMR spectroscopy. Careful synthesis of a fluorenylmethyloxycarbonyl- and trityl-protected, C2-deuterated histidine produces a vibrational-probe-equipped amino acid that can readily be incorporated into any peptide accessible by standard solid-phase methods. The frequency of the unique, Raman-active stretching vibration of this C2-D probe is a clear reporter of the protonation state of histidine. We investigate here a pH-sensitive peptide that self-assembles to form a hydrogel at neutral pH. The pKa of the lone histidine residue in the peptide, which is likely responsible for this pH-dependent behavior, cannot be investigated by NMR spectroscopy because of the supramolecular, soft nature of the gel. However, after synthesizing a C2-deuterated-histidine-containing peptide, we were able to follow the protonation state of histidine throughout a pH titration using Raman difference spectroscopy, thereby precisely determining the pKa of interest.
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| 2. |
- Engdahl, Anders, et al.
(författare)
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Microspectroscopic infrared specular reflection studies of multi-component urinary stones at beamline D7 at the MAX IV laboratory, Lund Sweden
- 2015
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Ingår i: IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves. - 9781479982721
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Konferensbidrag (refereegranskat)abstract
- At the beamline D7 at the MAX III ring at the MAX IV laboratory we have a setup for infrared microspectroscopy which is usable from 30 to 10000 cm-1. In this project specular reflection infrared microspectroscopy was used for chemical imaging of cross-sectioned urinary stones. to determine their chemical composition and morphology simultaneously. Absorption spectral bands were recovered from reflection spectra by Kramers-Kronig transform. Use of far-infrared radiation provides high-contrast images and allows more precise constituent distribution determinations than mid-infrared because band asymmetry after the transform caused by diffuse reflection is less in the far-infrared.
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| 3. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Mafla-Endara, Paola M, et al.
(författare)
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Exposure to polystyrene nanoplastics reduces bacterial and fungal biomass in microfabricated soil models
- 2023
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Ingår i: Science of the Total Environment. - 1879-1026. ; 904
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Tidskriftsartikel (refereegranskat)abstract
- Nanoplastics have been proven to induce toxicity in diverse organisms, yet their effect on soil microbes like bacteria and fungi remains largely unexplored. In this paper, we used micro-engineered soil models to investigate the effect of polystyrene (PS) nanospheres on Pseudomonas putida and Coprinopsis cinerea. Specifically, we explored the effects of increasing concentrations of 60 nm carboxylated bovine serum albumin (BSA) coated nanospheres (0, 0.5, 2, and 10 mg/L) on these bacterial and fungal model organisms respectively, over time. We found that both microorganisms could disperse through the PS solution, but long-distance dispersal was reduced by high concentrations. Microbial biomass decreased in all treatments, in which bacteria showed a linear dose response with the strongest effect at 10 mg/L concentration, and fungi showed a non-linear response with the strongest effect at 2 mg/L concentration. At the highest nanoplastics concentration, the first colonizing fungal hyphae adsorbed most of the PS nanospheres present in their vicinity, in a process that we termed the 'vacuum cleaner effect'. As a result, the toxicity effect of the original treatment on subsequently growing fungal hyphae was reduced to a growth level indistinguishable from the control. We did not find evidence that nanoplastics are able to penetrate bacterial nor fungal cell walls. Overall, our findings provide evidence that nanoplastics can cause a direct negative effect on soil microbes and highlight the need for further studies that can explain how the microbial stress response might affect soil functions.
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| 5. |
- Mafla-Endara, Paola Micaela, et al.
(författare)
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Microfluidic chips provide visual access to in situ soil ecology
- 2021
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Microbes govern most soil functions, but investigation of these processes at the scale of their cells has been difficult to accomplish. Here we incubate microfabricated, transparent ‘soil chips’ with soil, or bury them directly in the field. Both soil microbes and minerals enter the chips, which enables us to investigate diverse community interdependences, such as inter-kingdom and food-web interactions, and feedbacks between microbes and the pore space microstructures. The presence of hyphae (‘fungal highways’) strongly and frequently increases the dispersal range and abundance of water-dwelling organisms such as bacteria and protists across air pockets. Physical forces such as water movements, but also organisms and especially fungi form new microhabitats by altering the pore space architecture and distribution of soil minerals in the chip. We show that soil chips hold a large potential for studying in-situ microbial interactions and soil functions, and to interconnect field microbial ecology with laboratory experiments.
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| 6. |
- Pucetaite, Milda, et al.
(författare)
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Microspectroscopic infrared specular reflection chemical imaging of multi-component urinary stones: MIR vs. FIR
- 2014
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Ingår i: Central European Journal of Chemistry. - : Walter de Gruyter GmbH. - 1895-1066. ; 12:1, s. 44-52
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Tidskriftsartikel (refereegranskat)abstract
- Specular reflection infrared microspectroscopy was used for chemical imaging of cross-sectioned urinary stones to determine their chemical composition and morphology simultaneously. Absorption spectral bands were recovered from reflection spectra by Kramers-Kronig transform. FUse of far-infrared radiation provides high-contrast images and allows more precise constituent distribution determinations than mid-infrared because band asymmetry after the transform caused by diffuse reflection is less in the far-infrared.
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| 7. |
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| 8. |
- Pucetaite, Milda, et al.
(författare)
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Shining new light into soil systems : Spectroscopy in microfluidic soil chips reveals microbial biogeochemistry
- 2021
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 153
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Tidskriftsartikel (refereegranskat)abstract
- Microfluidic soil chips render optical access to the naturally opaque soil systems and enable direct investigation of microbial growth and interactions in micro-structurally and chemically controlled environments. However, chemical analyses of these interactions at high spatial and temporal resolution are still lacking. Here we propose that the use of advanced microspectroscopy techniques, namely infrared absorption, Raman scattering and synchrotron radiation based X-ray microspectroscopy, in microfluidic soil chips would make it possible to approach these phenomena. They allow monitoring biogeochemical processes in and around soil microbial cells growing in the reproducibly designed microenvironments within the chips at (sub)micrometer scale. Complementary use of several of the microspectroscopy techniques is beneficial for obtaining information about both molecular and elemental composition, oxidation states and local structure of the elements in the sample. Ultimately, we argue that microspectroscopy in microfluidic chips can lead to relevant breakthroughs in frontier research areas in soil science, such as (1) analysis of chemical responses of microbes to environmental triggers at micro-scale spatial resolution, (2) phenotypical identification and phylogenetic classification of single cells of soil microbes in situ, (3) determining spatially and time resolved effects of heavy metals and organic pollutants, including microplastics, on soils and (4) spatially resolved analysis of soil organic matter dynamics for better understanding of soil carbon storage. Tailoring the chip design to achieve optical transparency to the radiation type used by the different microspectroscopy methods is crucial to achieve this; therefore, we expect that this perspective will inspire the scientific community to use the proposed approaches and thus push both the technical development of the microspectroscopy suitable soil chips and the research frontier in soil science.
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| 9. |
- Simongini, Camilla, et al.
(författare)
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MICROPLASTICS IDENTIFICATION IN LANDFILL LEACHATES BY DIFFERENT SPECTROSCOPIC TECHNIQUES
- 2022
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Ingår i: Detritus. - : Eurowaste SRL. - 2611-4135. ; 18, s. 58-69
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Tidskriftsartikel (refereegranskat)abstract
- Discovered more than 40 years ago, microplastics have become a major environmental issue. With increasing global plastic production, microplastics are of growing concern. Landfills have been pinpointed as primary sources of microplastics to surface waters and they have, in fact, been identified and quantified as such. Due to their small size, different polymers and interfering non-plastic materials, microplastics are difficult to analyse in a complex matrix such as leachate. To elucidate the impact of pre-treatment on the performance of the most common microspectroscopical analytical methods employed, i.e., FT-IR and Raman, we re-examined previously pre-treated and analysed leachate samples. Additionally, we subjected duplicates of previously analysed samples to different concentrations of H2O2 with varied reaction times to digest and remove non-plastic organic matter. The pre-treated samples were subjected density separation and (re-)analysed by means of FT-IR and Raman microspectroscopy. Larger particles were also analysed by near-infrared (NIR) hyperspectral imaging. We found the concentration of H2O2 to impact the possibility of identifying and quantifying PET particles, with Raman scattering microspectroscopy enabling more particles to be counted than with FT-IR. This is likely due to the increased detectable particle size range, from around 50 μm for FT-IR to 1 μm for Raman scattering microspectroscopy. Optimized H2O2 concentration with subsequent density separation enabled to clearly identify numerous PE particles, but also PP, PS, and PET particles and carbon compounds with Raman scattering microspectroscopy. Hyperspectral imaging performed well for particles larger than 30 μm.
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| 10. |
- Tamosaityte, Sandra, et al.
(författare)
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Raman spectroscopy as a non-destructive tool to determine the chemical composition of urinary sediments
- 2021
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Ingår i: Comptes Rendus. Chimie. - : Cellule MathDoc/CEDRAM. - 1631-0748 .- 1878-1543. ; 24
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Tidskriftsartikel (refereegranskat)abstract
- Urolithiasis is a common disease worldwide, but its causes are still not well understood. In many cases, crystalluria provides an early indication of urinary stone formation, and characterisation of the urinary deposits could help doctors to take early preventative measures to stop their further growth. Nowadays, the gold standard for the analysis of urinary deposits is optical microscopy, but the morphology-based information it provides can often be unreliable and incomplete, particularly for deposits with no defined crystalline structure. In response to the need of a more attested method, we used Raman spectroscopy to determine the chemical composition of urinary deposits and urinary stones of 15 patients with urolithiasis in order to find out whether direct correlation between the composition of the corresponding stones and the deposits exists. We found that the main chemical compounds typically constituting urinary stones also form the deposits and that their composition correlates in eleven out of fifteen cases. However, brushite deposits that we found in two cases did not result in brushite, but mixed calciumoxalate monohydrate and phosphate stones. Overall, Raman spectroscopy is an informative and reliable method that can be used for analysis of urinary sediments for early diagnosis of urinary stone formation.
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