Elmiladi, Nouri Mokhtar: Proton Spin-Lattice Relaxation in Colloidal Aqueous Solutions with Resonant Ultrasound. - Bonn, 2010. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5N-22404
@phdthesis{handle:20.500.11811/4639,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5N-22404,
author = {{Nouri Mokhtar Elmiladi}},
title = {Proton Spin-Lattice Relaxation in Colloidal Aqueous Solutions with Resonant Ultrasound},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2010,
month = aug,

note = {Iron oxide nanoparticles have been extensively used in biomedical applications as a result of their magnetic properties. These magnetic nanoparticles are already used as contrast agents in magnetic resonance imaging (MRI). In this work, a method has been developed involving the application of ultrasound (US) while performing proton nuclear magnetic resonance spectroscopy to colloidal aqueous solutions. US is applied to samples of aqueous solutions containing specially prepared magnetic nanoparticles. The magnetic nanoparticles are chemically attached with antibody molecules from one side only such that their center of mass is different from their center of geometry. Two sizes of magnetic particles were used for measurements. 1.3 µm magnetic particles (MPs) were attached with IgM antibody molecules. 50 nm magnetic nanoparticles (MNPs) were attached with IgG antibody molecules. When subjected to US wave, these asymmetric particles tilted along with the vibrational movement. This behavior is effective on the change of the longitudinal relaxation rate only if the US frequency matches the proton Larmor frequency. To investigate this influence, an inversion recovery sequence was used. The amplitudes of the fast Fourier transform (FFT) of the free induction decays of the 90° read-out pulse were analyzed for different samples. No changes of the FFT amplitudes with and without US were observed for samples of distilled water and aqueous solutions of symmetric MNPs. However, a decrease in the FFT amplitudes with US turned on was observed for the aqueous solutions of asymmetric MNPs. The relative signal loss is greater for an aqueous solution containing 50 nm MNPs with IgG antibody molecules attached compared to an aqueous solution containing 1.3 µm MPs with IgM antibody molecules attached. This effect was observed particularly when the US frequency matched the proton Larmor frequency of the solvent. The measurements show that the relative signal loss with and without US depends on the power and pulse length of the applied resonant US.},
url = {http://hdl.handle.net/20.500.11811/4639}
}

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