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Träfflista för sökning "WFRF:(Nilsson Maria 1957 ) ;hsvcat:2"

Sökning: WFRF:(Nilsson Maria 1957 ) > Teknik

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1.
  • Sepehri, Sobhan, 1986, et al. (författare)
  • Homogeneous Differential Magnetic Assay
  • 2019
  • Ingår i: Acs Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 4:9, s. 2381-2388
  • Tidskriftsartikel (refereegranskat)abstract
    • Assays are widely used for detection of various targets, including pathogens, drugs, and toxins. Homogeneous assays are promising for the realization of point-of-care diagnostics as they do not require separation, immobilization, or washing steps. For low concentrations of target molecules, the speed and sensitivity of homogeneous assays have hitherto been limited by slow binding kinetics, time-consuming amplification steps, and the presence of a high background signal. Here, we present a homogeneous differential magnetic assay that utilizes a differential magnetic readout that eliminates previous limitations of homogeneous assays. The assay uses a gradiometer sensor configuration combined with precise microfluidic sample handling. This enables simultaneous differential measurement sample containing a synthesized Vibrio cholerae target and a negative control sample, which reduces the background signal and increases the readout speed. Very low concentrations of targets down to femtomolar levels are thus detectable without any additional amplification of the number of targets. Our homogeneous differential magnetic assay method opens new possibilities for rapid and highly sensitive diagnostics at the point of care.
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2.
  • Ahrentorp, Fredrik, et al. (författare)
  • Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils
  • 2017
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 427, s. 14-18
  • Tidskriftsartikel (refereegranskat)abstract
    • We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 mu m. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 mu L) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.
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3.
  • Sepehri, Sobhan, 1986, et al. (författare)
  • Characterization of Binding of Magnetic Nanoparticles to Rolling Circle Amplification Products by Turn-On Magnetic Assay
  • 2019
  • Ingår i: Biosensors-Basel. - : MDPI AG. ; 9:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The specific binding of oligonucleotide-tagged 100 nm magnetic nanoparticles (MNPs) to rolling circle products (RCPs) is investigated using our newly developed differential homogenous magnetic assay (DHMA). The DHMA measures ac magnetic susceptibility from a test and a control samples simultaneously and eliminates magnetic background signal. Therefore, the DHMA can reveal details of binding kinetics of magnetic nanoparticles at very low concentrations of RCPs. From the analysis of the imaginary part of the DHMA signal, we find that smaller MNPs in the particle ensemble bind first to the RCPs. When the RCP concentration increases, we observe the formation of agglomerates, which leads to lower number of MNPs per RCP at higher concentrations of RCPs. The results thus indicate that a full frequency range of ac susceptibility observation is necessary to detect low concentrations of target RCPs and a long amplification time is not required as it does not significantly increase the number of MNPs per RCP. The findings are critical for understanding the underlying microscopic binding process for improving the assay performance. They furthermore suggest DHMA is a powerful technique for dynamically characterizing the binding interactions between MNPs and biomolecules in fluid volumes.
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4.
  • Montelius, Mikael, 1979, et al. (författare)
  • Identification of Potential MR-Derived Biomarkers for Tumor Tissue Response to 177Lu-Octreotate Therapy in an Animal Model of Small Intestine Neuroendocrine Tumor.
  • 2018
  • Ingår i: Translational oncology. - : Elsevier BV. - 1936-5233. ; 11:2, s. 193-204
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnetic resonance (MR) methods enable noninvasive, regional tumor therapy response assessment, but associations between MR parameters, underlying biology, and therapeutic effects must be investigated. The aim of this study was to investigate response assessment efficacy and biological associations of MR parameters in a neuroendocrine tumor (NET) model subjected to radionuclide treatment. Twenty-one mice with NETs received 177Lu-octreotate at day 0. MR experiments (day -1, 1, 3, 8, and 13) included T2-weighted, dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) and relaxation measurements (T1/T2*). Tumor tissue was analyzed using proteomics. MR-derived parameters were evaluated for each examination day and for different radial distances from the tumor center. Response assessment efficacy and biological associations were evaluated using feature selection and protein expression correlations, respectively. Reduced tumor growth rate or shrinkage was observed until day 8, followed by reestablished growth in most tumors. The most important MR parameter for response prediction was DCE-MRI-derived pretreatment signal enhancement ratio (SER) at 40% to 60% radial distance, where it correlated significantly also with centrally sampled protein CCD89 (association: DNA damage and repair, proliferation, cell cycle arrest). The second most important was changed diffusion (D) between day -1 and day 3, at 60% to 80% radial distance, where it correlated significantly also with peripherally sampled protein CATA (association: oxidative stress, proliferation, cell cycle arrest, apoptotic cell death). Important information regarding tumor biology in response to radionuclide therapy is reflected in several MR parameters, SER and D in particular. The spatial and temporal information provided by MR methods increases the sensitivity for tumor therapy response.
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5.
  • Olsson, Mattias, 1975, et al. (författare)
  • Sorption of trivalent plutonium onto UO2 and the effect of the solid phase on the Pu oxidation state
  • 2005
  • Ingår i: Radiochimica Acta. ; 93, s. 341-346
  • Tidskriftsartikel (refereegranskat)abstract
    • A problem with plutonium in sorption studiesis its tendency to occur in a mix of oxidation states. Thiswork was a study of the sorption of plutonium on the solidphase UO2 in a perchlorate medium as a function of pH where plutonium is kept in its trivalent oxidation state.Experiments also showed that uranium(IV) oxide can reducePu(IV) to Pu(III) in an acidic solution and maintain it in thatstate. It was observed at the same time that the chemicallyinert solid phases TiO2 and ThO2 possibly increase the rateof disproportionation of Pu(IV) at a pH of about 0.5. Inaccordance with previous studies MnO2 was found to have anoxidizing effect, converting Pu(IV) into Pu(VI).A comparison is made between the sorption of Th(IV),Pu(III) and Co(II) on UO2 and TiO2, and Pu(VI) on TiO2.
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