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Organolead halide perovskites currently are the new front-runners as light absorbers in hybrid solar cells, as they combine efficiencies passing already 20% with deposition temperatures below 100 °C and cheap solution-based fabrication routes. Long-term stability remains a major obstacle for application on an industrial scale. Here, it is demonstrated that significant decomposition effects already occur during annealing of a methylammonium lead triiode perovskite at 85 °C even in inert atmosphere thus violating international standards. The observed behavior supports the view of currently used perovskite materials as soft matter systems with low formation energies, thus representing a major bottleneck for their application, especially in countries with high average temperatures. This result can trigger a broader search for new perovskite families with improved thermal stability.

Biodegradable polymers can be used in variable applications within the field of biomedical sciences such as drug delivery systems, scaffolding, sutures and other. To produce these structures a novel and efficient method is explored to synthesize new materials with superior characteristics that may replace existing polymers in the future. In this project polymer networks are synthesized using thiol-ene click step growth polymerization. The used non-radical thiol-ene Michael addition is a fast reaction with high yields, which proceeds at room temperature with small amounts of catalyst, a tertiary phosphine. For the purpose of this thiol-ene step growth polymerization a dithiol homotelechelic polystyrene polymer is synthesized via RAFT polymerization using a bifunctional RAFT-agent (BiDoPAT) and subsequent aminolysis of the RAFT end groups. The resulting polymer is successfully conjugated with acrylic linkers (Mn of 7000 and tailing towards 100000 g'mol-1). By using acrylic linkers biodegradability is introduced via its ester moieties, which are spread throughout the entire molecule. A Baylis-Hillman step growth polymerization is a different method to produce polymers containing ester and accessible vinyl functionalities. The latter can be exploited to crosslink the residual Baylis-Hillman polymers. Furthermore a preliminary study was carried out using a suspension technique to synthesize degradable particles. The characteristics of the above mentioned polymers can be further tuned depending on the product's fate

Multifunctional nanoparticles combine several properties into one stable construct, providing a very promising tool for the medical world. However, converting the theoretical designs into a usable application is a multi-step process that usually costs a lot of time, effort and money. Therefore, the aim of this thesis is to advance the research of designing multifunctional nanoparticles. The first part of the thesis covers the production of in situ surface functionalized polymer nanoparticles for targeting purposes. The second part of the thesis covers the production of fluorescent polymer nanoparticles, comprising of the conjugated polymer MDMO-PPV, for in vivo bioimaging. For the first time, these polymer nanoparticles were studied for their cytotoxicity and cell-uptake behavior using HMEC-1 cells. All the particles described in this work are synthesized using the miniemulsion technique.

The detection of specific DNA sequences is useful for the detection of specific DNA sequences in gene expression studies and for the detection of mutations in the genome. Expensive, time-consuming and multi-step techniques are currently used for detecting specific DNA sequences. Some examples are denaturation gradient gel electrophoresis (DGGE), Southern blotting and micro arrays. For these optical techniques labeling or staining is required to visualize the result. Another possible technique is surface plasmon resonance (SPR), for this technique no labeling is required, but miniaturization is hard to achieve. Therefore this research aims to create a sensitive and selective biosensor which overcomes the before mentioned drawbacks. A biosensor which can be miniaturized to a hand-held device for point-of-care testing. Nanoparticles, made by the micellar approach, are obtained by plasma etching of the metal salt loaded micelles deposited on a substrate (silicon, tantalum pentoxide and