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978-3-8439-1842-8, Reihe Physikalische Chemie
Analytische und mikroskopische Untersuchung der Interaktion von funktionalisierten Goldnanopartikeln mit dem Interleukin-6-Rezeptor
192 Seiten, Dissertation Universität Hamburg (2014), Softcover, A5
In order to increase the efficiency of therapeutical applications an elementary understanding of the interaction between pharmaceutical ligand and cellular receptor is required. Nanoparticles as optical labels allow tracking of the mobile partner and therefore the characterization of its binding behavior on the cell surface. In this thesis gold nanoparticles exhibiting diameters from few to several tens of nanometers act as a label for the antibody anti-human CD126 and the aptamer AIR-3A to visualize their binding to the Interleukin-6-receptor on the surface of mammalian cells. The aptamer-conjugates were covered with polyethylene glycols in order to obtain stable particles and to avoid unspeciﬁc uptake, while the antibody was bound via the streptavidin-biotin-system to the particle surface.
The capability of the conjugates to interact with the cellular receptor on a speciﬁc level was proven by analyzing the amount of gold in the cell suspension using inductively coupled plasma mass spectrometry. It could be shown that a supersaturation of the conjugates with additional polyethylenglycol or bovine serum albumin optimized the speciﬁc interaction of both functionalized particle variants with the cell. The antibody-conjugates showed a strong binding to the cell receptor independently from incubation temperature which was at least up to six times higher than the interaction of their passivated counterparts. However, after binding to the receptor the aptamer-conjugates additionally showed a speciﬁc uptake into the cells which was dependent on the incubation temperature. In addition, the speciﬁcity of the uptake was correlated to the size of the gold particles as well as the duration of the incubation period. Furthermore, a saturation of the particle uptake could be achieved at a aptamer concentration of 100 nm. Finally uptake rates of up to six times higher than those of completely passivated gold particles could be attained for the aptamer-presenting conjugates.
To visualize the binding events optical scattering and ﬂuorescence lifetime images were compared to images obtained from scanning electron microscopy in order to directly count the number of gold nanoparticles on the cell surface and examine the binding behavior of the particles. It could be found that the aptamer- as well as the antibody-conjugates accumulated in groups on the cell surface whereas passivated particles bound to the cells at a lower rate without any clustering.