Synthesis and Surface Modification of Inorganic Nanoparticles for Application in Physics and Medicine
The core focus of this cumulative thesis is the synthesis, the characterization, and the polymer coating or the surface modification of different types of inorganic nanoparticles (NPs), e.g., semiconductor, magnetic, plasmonic, and titanium oxide NPs. These NPs are used in the field of physics, biot...
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|The core focus of this cumulative thesis is the synthesis, the characterization, and the polymer coating or the surface modification of different types of inorganic nanoparticles (NPs), e.g., semiconductor, magnetic, plasmonic, and titanium oxide NPs. These NPs are used in the field of physics, biotechnology, and in nanomedicine or life sciences for both diagnosis and therapy. The applications of these NPs depend on their unique properties, which are correlated to their size, shape, and the material composition.
The colloidal stability of these nanocrystals or NPs in different media (e.g. organic, water, cell culture media) was achieved by means of capping agents or by wrapping suitable ligands or surfactants around the core of the NPs. The colloidal NPs that were synthesised during this research work were capped with hydrophobic ligands (e.g. oleic acid, oleylamine, etc.) to keep them stable in the organic media, e.g., toluene, chloroform, etc. The phase transfer from organic to aqueous is a mandatory step prior to their use in the few desired applications, especially when these NPs are exposed to aqueous medium or cell media. This is carried out by wrapping the NPs with an amphiphilic polymer, i.e., poly(isobutylene-alt-maleic anhydride) (Mw= 6000 Da) that is grafted with hydrophobic side chains of dodecylamine.
The mentioned four types of produced NPs were: (i) Semiconductor NPs which include the hydrophobic cadmium sulfide (CdS) quantum dots (QDs) that are used: for organic scintillation neutrino detection experiments; for PPO (2, 5-diphenyloxazole) styrene based plastic scintillator detectors; for time resolved spectral measurement, and for fluorescence studies with different surface coatings; additionally, water soluble CdS, manganese doped CdS, and zinc sulphide (ZnS) with and without manganese doping were synthesized and engineered to run several experiments on nanomaterials’ (NMs) behavior in environmental media, e.g., river and lake water; (ii) magnetic NPs (MNPs) that include core only (iron oxide, e.g. magnetite) and core shell composite iron oxide magnetic NPs combined with cobalt and manganese ferrites; (iii) plasmonic NPs such as gold and silver NPs that were used in combination with iron-oxide NPs (4 nm each) for toxicity screening and dose determination assays, and (vi) titanium dioxide
(TiO2) NPs with different sizes and shapes (i.e. cube, rods, plates, and bipyramids), which were used for in vivo experiments: To evaluate the bio-distribution, organ accumulation, biological barrier passage, and potential organ toxicity after a single intravenous administration of TiO2 NPs, and to assess the influence of the TiO2 NPs shape and geometry on the mentioned effects. Furthermore TiO2 NPs were also used to perform few more in vivo studies to investigate: (i) The effect of biological environment (e.g. lung lining liquid, saliva, gastric/intestinal fluids) on NPs’ behaviour and toxicity, using complex co-culture systems for the intestine and alveoli, (ii) the effect of NPs on the activation of the inflammasome, and (iii) the influence of NPs on the maturation and activation of dendritic cells.
In addition to above mentioned experiments for synthesis and surface modification another study was carried out with the aim to transfer three different types of NPs (i.e. plasmonic, fluorescent and magnetic) in aqueous phase to be employed in hydrogels, aerogels, and heterogels applications. In this study bimetallic (gold-copper) plasmonic nanocubes, fluorescent (cadmium selenide/CdS) core shell nanorods and magnetic iron oxide (Fe3O4) nanospheres were successfully transferred to the aqueous phase irrespective of their different sizes ranging from 5-40 nm in at least one dimension.
All water soluble NPs were cleaned by means of gel electrophoresis or by ultracentrifugation to get rid of micelles (empty polymer) followed by sterilization for all in vivo studies. The qualitative and quantitative analyses all of these NPs were performed by means of different characterization techniques, e.g., ultraviolet-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering, zeta potential measurements gel electrophoresis, transmission electron microscopy, inductively coupled plasma mass spectrometry, and the X-ray diffraction analysis.