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    Optical concentration of gold nanoparticles as a new concept of analytical sensitivity

    , Article Instrumentation Science and Technology ; 2020 Vaziri Heshi, S ; Shokoufi, N ; Seyed Reihani, S. N ; Sharif University of Technology
    Bellwether Publishing, Ltd  2020
    Concentration procedures have always been implemented when trace analysis of compounds in real matrices is contemplated. A variety of concentration strategies have been reported aiming at decreasing the limits of detection (LODs). The optical concentration of the substance in solution is one of the novel concepts for the enhancement of the analytical sensitivity. In this study, the optical concentration has been measured by the trapping of gold nanoparticles ((Formula presented.) nm) dispersed in water at low-concentrations at the focal volume of the laser beam. The influence of factors such as the time of gold nanoparticle trapping, the size of the nanoparticles, the intensity of the laser... 

    Dynamics of membrane nanotubes coated with I-BAR

    , Article Scientific Reports ; Volume 6 , 2016 ; 20452322 (ISSN) Barooji, Y. F ; Rørvig Lund, A ; Semsey, S ; Seyed Reihani, S. N ; Bendix, P. M ; Sharif University of Technology
    Nature Publishing Group  2016
    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes.... 

    Stochastic analysis of time series for the spatial positions of particles trapped in optical tweezers

    , Article Scientific Reports ; Volume 7, Issue 1 , 2017 ; 20452322 (ISSN) Mousavi, S. M ; Seyed Reihani, S. N ; Anvari, G ; Anvari, M ; Alinezhad, H. G ; Rahimi Tabar, R. M ; Sharif University of Technology
    We propose a nonlinear method for the analysis of the time series for the spatial position of a bead trapped in optical tweezers, which enables us to reconstruct its dynamical equation of motion. The main advantage of the method is that all the functions and parameters of the dynamics are determined directly (non-parametrically) from the measured series. It also allows us to determine, for the first time to our knowledge, the spatial-dependence of the diffusion coefficient of a bead in an optical trap, and to demonstrate that it is not in general constant. This is in contrast with the main assumption of the popularly-used power spectrum calibration method. The proposed method is validated...