Asymmetric Oligothiophenes : Chemical Evolution of Multimodal Amyloid Ligands

Sammanfattning: Luminescent conjugated polymers (LCPs) and luminescent conjugated oligothiophenes (LCOs) can be used as molecular probes to study diseases associated with protein aggregation. The conventionally used dyes to study and detect protein aggregates, denoted amyloid, have been Congo red (CR) and Thioflavin T (ThT). In contrast to these amyloid ligands, LCOs offer the possibility to detect aggregated proteinaceous species occurring at earlier stages of amyloid formation as well as to distinguish different morphotypes of protein aggregates. The interaction between the LCOs and the protein deposits can be studied by fluorescence spectroscopy and microscopy both in vitro and ex vivo. In this thesis we report the development of multimodal asymmetric LCOs that can be utilized with two novel techniques, Surface Plasmon Resonance (SPR) and Positron Emission Tomography (PET), to study the interaction between LCO and amyloid fibrils in real time. With SPR, we have been able to determine binding affinities between LCO and amyloid, and with PET we have shown that radiolabelled LCOs can be used as a non-invasive method to study amyloid deposits in vivo. In addition, by alteration of the backbone (change of thiophene units), and of adding different side chains functionalities, we have shown that the properties of the amyloid ligands have a huge impact of the binding to different stages or forms of protein aggregates. By making asymmetrical LCOs, which can be attached to a surface, we also foresee a methodology that will offer the possibility to create a sensitive and selective detection method, and maybe lead to a lab-on-a-chip-application.