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Sökning: WFRF:(Uvdal Peter)

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1.
  • Lindgren, Johan, et al. (författare)
  • Interpreting melanin-based coloration through deep time : A critical Review
  • 2015
  • Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : Royal Society of London. - 0962-8452 .- 1471-2954. ; 282:1813
  • Forskningsöversikt (refereegranskat)abstract
    • Colour, derived primarily from melanin and/or carotenoid pigments, is integral to many aspects of behaviour in living vertebrates, including social signalling, sexual display and crypsis. Thus, identifying biochromes in extinct animals can shed light on the acquisition and evolution of these biological traits. Both eumelanin and melanin-containing cellular organelles (melanosomes) are preserved in fossils, but recognizing traces of ancient melanin-based coloration is fraught with interpretative ambiguity, especially when observations are based on morphological evidence alone. Assigning microbodies (or, more often reported, their ‘mouldic impressions’) as melanosome traces without adequately excluding a bacterial origin is also problematic because microbes are pervasive and intimately involved in organismal degradation. Additionally, some forms synthesize melanin. In this review, we survey both vertebrate and microbial melanization, and explore the conflicts influencing assessment of microbodies preserved in association with ancient animal soft tissues.We discuss the types of data used to interpret fossil melanosomes and evaluate whether these are sufficient for definitive diagnosis. Finally, we outline an integrated morphological and geochemical approach for detecting endogenous pigment remains and associated microstructures in multimillion-year-old fossils.
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2.
  • Assenhöj, Maria, et al. (författare)
  • Protein interaction, monocyte toxicity and immunogenic properties of cerium oxide crystals with 5% or 14% gadolinium, cobalt oxide and iron oxide nanoparticles–an interdisciplinary approach
  • 2021
  • Ingår i: Nanotoxicology. - : Taylor and Francis Ltd.. - 1743-5390 .- 1743-5404. ; 15:8, s. 1035-1038
  • Tidskriftsartikel (refereegranskat)abstract
    • Metal oxide nanoparticles are widely used in both consumer products and medical applications, but the knowledge regarding exposure-related health effects is limited. However, it is challenging to investigate nanoparticle interaction processes with biological systems. The overall aim of this project was to improve the possibility to predict exposure-related health effects of metal oxide nanoparticles through interdisciplinary collaboration by combining workflows from the pharmaceutical industry, nanomaterial sciences, and occupational medicine. Specific aims were to investigate nanoparticle-protein interactions and possible adverse immune reactions. Four different metal oxide nanoparticles; CeOx nanocrystals with 5% or 14% Gd, Co3O4, and Fe2O3, were characterized by dynamic light scattering and high-resolution transmission electron microscopy. Nanoparticle-binding proteins were identified and screened for HLA-binding peptides in silico. Monocyte interaction with nanoparticle–protein complexes was assessed in vitro. Herein, for the first time, immunogenic properties of nanoparticle-binding proteins have been characterized. The present study indicates that especially Co3O4-protein complexes can induce both ‘danger signals’, verified by the production of inflammatory cytokines and simultaneously bind autologous proteins, which can be presented as immunogenic epitopes by MHC class II. The clinical relevance of these findings should be further evaluated to investigate the role of metal oxide nanoparticles in the development of autoimmune disease. The general workflow identified experimental difficulties, such as nanoparticle aggregate formation and a lack of protein-free buffers suitable for particle characterization, protein analyses, as well as for cell studies. This confirms the importance of future interdisciplinary collaborations. © 2021 The Author(s). 
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4.
  • Borgh, Annika, et al. (författare)
  • A new route to the formation of biomimetic phosphate assemblies on gold : Synthesis and characterization
  • 2006
  • Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 295:1, s. 41-49
  • Tidskriftsartikel (refereegranskat)abstract
    • A biomimetic model system based on long-chain alkanethiols tailored with serine, threonine and tyrosine side-chain groups is created as a platform for the study of phosphorylated amino acids. The phosphorylated analogues are synthesized with protective tert-butyl groups that after assembly on thin polycrystalline gold films are removed in an acidic deprotection solution to form the corresponding phosphate self-assembled monolayers (SAMs). The SAMs are thoroughly characterized with null ellipsometry, contact angle goniometry, infrared reflection–absorption spectroscopy and X-ray photoelectron spectroscopy. The assembly and the subsequent deprotection process are optimized with respect to molecular orientation and chain conformation by varying the incubation time and the exposure time to the deprotection solution. The high quality of the generated SAMs suggests that the present assembly/deprotection approach is an attractive alternative when traditional synthetic routes become demanding because of solubility problems.
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5.
  • Bunnfors, Kalle, et al. (författare)
  • Nanoparticle activated neutrophils-on-a-chip : A label-free capacitive sensor to monitor cells at work
  • 2020
  • Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 313
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutrophil granulocytes are the most abundant white blood cells in mammals and vital components of the immune system. They are involved in the early phase of inflammation and in generation of reactive oxygen species. These rapid cell-signaling communicative processes are performed in the time frame of minutes. In this work, the activity and the response of neutrophil granulocytes are monitored when triggered by cerium-oxide based nanoparticles, using capacitive sensors based on Lab-on-a-chip technology. The chip is designed to monitor activation processes of cells during nanoparticle exposure, which is for the first time recorded on-line as alteration of the capacitance. The complementary metal oxide semiconductor engineering chip design is combined with low temperature co-fired ceramic, LTCC, packaging technology. The method is label free and gently measures cells on top of an insulating surface in a weak electromagnetic field, as compared to commonly used four-point probes and impedance spectroscopy electric measurements where electrodes are in direct contact with the cells. In summary, this label free method is used to measure oxidative stress of neutrophil granulocytes in real time, minute by minute and visualize the difference in moderate and high cellular workload during exposure of external triggers. It clearly shows the capability of this method to detect cell response during exposure of external triggers. In this way, an informationally dense non-invasive method is obtained, to monitor cells at work.
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6.
  • De La Garza, Randolph Glenn, et al. (författare)
  • An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes
  • 2022
  • Ingår i: Scientific Reports. - : Nature Research. - 2045-2322. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid—unlike its scaly living descendants—combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle. © 2022, The Author(s).
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7.
  • Eriksson, Peter, 1989- (författare)
  • Cerium Oxide Nanoparticles and Gadolinium Integration : Synthesis, Characterization and Biomedical Applications
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • A challenging task, in the area of magnetic resonance imaging is to develop contrast enhancers with built-in antioxidant properties. Oxidative stress is considered to be involved in the onset and progression of several serious conditions such as Alzheimer’s and Parkinson’s disease, and the possibility to use cerium-contained nanoparticles to modulate such inflammatory response has gained a lot of interest lately. The rare earth element gadolinium is, due to its seven unpaired f-electrons and high symmetry of the electronic state, a powerful element for contrast enhancement in magnetic resonance imaging. Chelates based on gadolinium are the most commonly used contrast agents worldwide. When introducing external contrast agents there is always a risk that it may trigger inflammatory responses, why there is an urgent need for new, tailor-made contrast agents.Small sized cerium oxide nanoparticles have electronic structures that allows coexistence of oxidation states 3+ and 4+ of cerium, which correlates to applicable redox reactions in biomedicine. Such cerium oxide nanoparticles have recently shown to exhibit antioxidant properties both in vitro and in vivo, via the mechanisms involving enzyme mimicking activity.This PhD project is a comprehensive investigation of cerium oxide nanoparticles as scaffold materials for gadolinium integration. Gadolinium is well adopted into the crystal structure of cerium oxide, enabling the combination of diagnostic and therapeutic properties into a single nanoparticle. The main focus of this thesis project is to design cerium oxide nanoparticles with gadolinium integration. A stepwise approach was employed as follows: 1) synthesis with controlled integration of gadolinium, 2) material characterization by means of composition crystal structure, size, and size distribution and 3) surface modification for stabilization. The obtained nanoparticles exhibit remarkable antioxidant capability in vitro and in vivo. They deliver strongly enhanced contrast per gadolinium in magnetic resonance imaging, compared to commercially available contrast agents.A soft shell of dextran is introduced to encapsulate the cerium oxide nanoparticles with integrated gadolinium, which protects and stabilizes the hard core and to increases their biocompatibility. The dextran-coating is clearly shown to reduce formation of a protein corona and it improves the dispersibility of the nanoparticles in cell media. Functionalization strategies are currently being studied to endow these nanoparticles with specific tags for targeting purposes. This will enable guidance of the nanoparticles to a specific tissue, for high local magnetic resonance contrast complemented with properties for on-site reduced inflammation.In conclusion, our cerium oxide nanoparticles with integrated gadolinium, exhibit combined therapeutic and diagnostic, i.e. theragnostic capabilities. This type of nanomaterial is highly promising for applications in the field of biomedical imaging.
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8.
  • Eriksson, Peter, et al. (författare)
  • Cerium oxide nanoparticles with antioxidant capabilities and gadolinium integration for MRI contrast enhancement
  • 2018
  • Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
  • Tidskriftsartikel (refereegranskat)abstract
    • The chelating gadolinium-complex is routinely used as magnetic resonance imaging (MRI) -contrast enhancer. However, several safety issues have recently been reported by FDA and PRAC. There is an urgent need for the next generation of safer MRI-contrast enhancers, with improved local contrast and targeting capabilities. Cerium oxide nanoparticles (CeNPs) are designed with fractions of up to 50% gadolinium to utilize the superior MRI-contrast properties of gadolinium. CeNPs are well-tolerated in vivo and have redox properties making them suitable for biomedical applications, for example scavenging purposes on the tissue-and cellular level and during tumor treatment to reduce in vivo inflammatory processes. Our near edge X-ray absorption fine structure (NEXAFS) studies show that implementation of gadolinium changes the initial co-existence of oxidation states Ce3+ and Ce4+ of cerium, thereby affecting the scavenging properties of the nanoparticles. Based on ab initio electronic structure calculations, we describe the most prominent spectral features for the respective oxidation states. The as-prepared gadolinium-implemented CeNPs are 3-5 nm in size, have r(1)-relaxivities between 7-13 mM(-1) s(-1) and show clear antioxidative properties, all of which means they are promising theranostic agents for use in future biomedical applications.
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9.
  • Eriksson, Peter, et al. (författare)
  • Cerium Oxide Nanoparticles with Entrapped Gadolinium for High T-1 Relaxivity and ROS-Scavenging Purposes
  • 2022
  • Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:24, s. 21337-21345
  • Tidskriftsartikel (refereegranskat)abstract
    • Gadolinium chelates are employed worldwide today as clinical contrast agents for magnetic resonance imaging. Until now, the commonly used linear contrast agents based on the rare-earth element gadolinium have been considered safe and well-tolerated. Recently, concerns regarding this type of contrast agent have been reported, which is why there is an urgent need to develop the next generation of stable contrast agents with enhanced spin-lattice relaxation, as measured by improved T-1 relaxivity at lower doses. Here, we show that by the integration of gadolinium ions in cerium oxide nanoparticles, a stable crystalline 5 nm sized nanoparticulate system with a homogeneous gadolinium ion distribution is obtained. These cerium oxide nanoparticles with entrapped gadolinium deliver strong T-1 relaxivity per gadolinium ion (T-1 relaxivity, r(1) = 12.0 mM(-1) s(-1)) with the potential to act as scavengers of reactive oxygen species (ROS). The presence of Ce3+ sites and oxygen vacancies at the surface plays a critical role in providing the antioxidant properties. The characterization of radial distribution of Ce3+ and Ce4+ oxidation states indicated a higher concentration of Ce3+ at the nanoparticle surfaces. Additionally, we investigated the ROS-scavenging capabilities of pure gadolinium-containing cerium oxide nanoparticles by bioluminescent imaging in vivo, where inhibitory effects on ROS activity are shown.
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10.
  • Gazdzicki, Pawel, et al. (författare)
  • Adsorption of intact methanol on Ru(0001)
  • 2009
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 130:22
  • Tidskriftsartikel (refereegranskat)abstract
    • Fourier transform infrared absorption spectroscopy has been used to study the adsorption of methanol on the clean Ru(0001) surface at T <= 80 K. Thereby, clear evidence for intact adsorption has been found. This observation contradicts previous studies which suggested an OH(OD) bond scission upon adsorption of methanol on Ru(0001), even at low temperatures, as well as partial recombinative desorption at higher T. Our conclusion is based on isotopic shifts of vibrational modes associated with the OH (OD) group of adsorbed CH3OH and CH3OD. Density functional theory (B3LYP) confirms these findings, as it reproduces the observed frequencies and isotopic shifts well. Additional support for our conclusion of nondissociative adsorption of methanol on Ru(0001) is provided by thermal desorption experiments of CH3OH coadsorbed with deuterium on Ru(0001). We find that CH3OD formation is clearly below detection threshold, while desorption of CH3OH is quite prominent; a recombinative desorption of dissociated methanol and hydrogen/deuterium as suggested in the literature is therefore discarded. At very low coverages and temperatures the presence of isolated methanol molecules or dimers is suggested. With increasing density or by annealing a low coverage methanol layer, hydrogen bonding leads to cluster formation, as evidenced by an intensity loss of those vibrational modes affected by hydrogen bonds, in conjunction with a substantial line broadening. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3151674]
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