• Gold nanoparticle hybrid systems

Eisold, Sabine; Simon, Ulrich (Thesis advisor); Wöll, Dominik (Thesis advisor)

Aachen (2018, 2019)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2018


This work includes the synthesis and characterization of various gold nanoparticle (AuNP) hybrid systems, in solution as well as on surfaces. Different interactions were used to bind AuNP to organic molecular systems: unspecific or electrostatic interactions and programmable interactions through the use of DNA. This has enabled the development of new multifunctional structures that could potentially be applied in biomedicine, e. g. as drug delivery systems. In the first part of this thesis, the formation of a hybrid system is described, consisting of negatively charged 1.4 nm cytotoxic AuNP and positively charged microgels (μGs). It was possible to release them by external stimuli such as pH and temperature change. In the second part of the thesis, the formation of hybrid systems by programmable interactions is described by using oligonucleotides (DNA for simplification) as linkers between 12 nm AuNP and μG. Different DNA-functionalized μGs were synthesized. The μGs were pNIPAM-, pNIPMAM and pVCL-based μGs into which DNA was covalently bound via corresponding co-monomers. Complementary DNA strands and DNA-functionalized AuNP could reversibly be attached to the DNA. These hybrid systems could be imaged by SEM-T and in situ-STEM, whereby the distribution of AuNP inside the μG was analyzed. A system with defined structure was developed by using DNA strands with hairpin motifs to connect the AuNPs. Thus, these structures should also be switchable. Dimers and networks were synthesized. The networks were synthesized by control of concentration of isotropically functionalized AuNP by combination of isotropically and anisotropically functionalized AuNP. The third part of the thesis describes the immobilization of μGs via DNA hybridization on AuNP immobilized on a substrate. The interactions of the μGs with the substrate were investigated and attempts were made to minimize the interaction by using a highly fluorinated backfill. DNA hybridization allowed μGs to be reversibly immobilized, which enabled further characterization by AFM and fluorescence microscopy.