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Träfflista för sökning "WFRF:(Nilsson Christer F.) ;pers:(Strømme Maria 1970)"

Sökning: WFRF:(Nilsson Christer F.) > Strømme Maria 1970

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1.
  • 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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3.
  • 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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4.
  • Sepehri, Sobhan, et al. (författare)
  • Study of magnetic beads-DNA coils binding kinetics using a differential homogeneous magnetic assay
  • 2019
  • Ingår i: Joint European Magnetic Symposia (JEMS) 2019. - Uppsala.
  • Konferensbidrag (refereegranskat)abstract
    • The binding kinetics of magnetic nanoparticles (MNPs) to rolling circle amplification products (RCPs) is investigated using a differential homogenous magnetic assay (DHMA)1. The DHMA utilizes a microfluidic device to measure the differential ac susceptibility signal between a reference and a test sample, taking advantage of the symmetry in a high-Tc SQUID gradiometer sensor2. The DHMA signal is related to the relative differences in the particle distribution of the two samples, and the background magnetic signal is thus eliminated. Therefore, minuscule changes in the nanoparticle’s concentration and size distribution of the test sample are directly detectable in the solution. This makes the DHMA a superior technique to characterize the binding interaction of the MNPs to biomolecules like RCPs specially at very low concentrations. The DHMA reveals that there is a competitive dynamic process between the MNP labelled RCPs and the unbound MNPs in the solution as a function of the RCP concentrations. The evidence of this dynamic in the signal fades as the MNP-RCP agglomerates are formed. The DHMA also shows that the smaller MNPs in the MNP size distribution take precedence over the larger MNP in immobilization on the RCPs. Comparing the DHMA responses with the turn-off detection method indicates that a full frequency range ac susceptibility observation is necessary when detecting low concentration of target RCPs. The findings are critical for understanding the underlying microscopic binding process and improving the assay performance. [1] Sepehri, S. et al, Differential homogeneous magnetic assay. Submitted. [2] Sepehri, S. et al. Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high-Tc SQUID magnetic readout. APL Bioeng. 2, 016102 (2018).
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  • Resultat 1-4 av 4

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