Gold Nanoparticles: Synthesis, Surface Modification and Functionalization for Biomedical Applications
The nanoparticles (NPs) surface plays an important role in the interaction of the NPs with surrounding environments, defines their fate in the biological media and it can be engineered to provide a large number of functional groups for different applications. The main topic of this thesis is the...
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|Zusammenfassung:||The nanoparticles (NPs) surface plays an important role in the interaction of the NPs with surrounding environments, defines their fate in the biological media and it can be engineered to provide a large number of functional groups for different applications. The main topic of this thesis is the synthesis, the surface modification and the characterization of gold NPs (GNPs). The NPs were prepared with different sizes (up to 100 nm) and shapes (spherical and rods). The employed NPs were prepared originally in aqueous medium, stabilized by citric ions in case of spherical GNPs (SGNPs) and by hexadecyltrimethylammonium bromide (CTAB) in case of gold nanorods (GNRs). These ligand molecules are weakly bound to the NPs surface and thus, they are unsuitable for biomedical applications. Stabilizing of these NPs was the target of this work and then, it was achieved by exchange these ligands by other molecules with higher affinity and finally wrapping the NPs with an amphiphilic polymer (poly(isobutylene-alt-maleic anhydride) dodecylamine grafted, (PMA)). The polymer coating technique has been used over the past years for coating of NPs, which are synthesized originally, and only dispersible in organic media. The NPs obtained using this methodology are highly stable in physiological media. Aiming to use this technique in water-soluble NPs, a new round-trip process was developed using a phase transfer step before the polymer coating. The NPs were stabilized with α-metoxi-ω-thiol-poly-(ethyleneglycol)- (PEG) chains (mPEG-SH (Mw= 750 Da)) and then transferred from water to chloroform using dodecylamine (DDA). The DDA-capped NPs were coated with a modified amphiphilic polymer due to the hydrophobic interaction between the hydrophobic ligands (carbon chains) on the surface of the NPs and the hydrophobic side chains of the used polymer. The resulted polymer coated NPs were cleaned and characterized using different techniques, such as agarose gel electrophoresis, UV-Vis spectroscopy, dynamic light scattering (DLS), laser Doppler anemometry (LDA) and transmission electron microscopy (TEM). Furthermore, the surface of the polymer-coated NPs was modified using different molecular weight of PEG to provide them with higher colloidal stability and prevent the formation of the so-called protein corona. The colloidal stability of all particles was assayed against different biological media via UV-Vis spectroscopy and DLS. The toxicity of these NPs was tested in cancer and non-cancer cells lines showing no-toxicity up to 1 mg/mL concentration levels. Additionally, the effect of NPs size, shape, and surface coating on their interaction with plasma proteins and blood cells was studied.|