Conjugated polyelectrolytes (CP) show interesting electrical and optical properties for organic electronics as well as for life science applications. Their possibilities of supramolecular assembly with nanowire like misfolded proteins, amyloids, as well as synthetic polypeptides or DNA forming conducting or luminescent nano composites is highly interesting as being a truly bottom up approach for fabrication of OLEDs, photovoltaic’s as well as logic devices. The conformation and aggregation dependent luminescence properties from the special class of CPs, Luminescent conjugated polyelectrolytes (LCP), have been utilised and developed as sensors to follow and study biomolecular interactions, DNA hybridisation, protein-protein interactions and staining of living cell cultures and tissue slides. In this thesis we are bringing the evolution a few steps further by applying new types of experimental techniques, such as light scattering and fluorescence correlation spectroscopy, combined with standard techniques as soft lithography and different spectroscopy techniques, to gain better knowledge of the optical behaviour of LCPs and their interactions with biomolecules. We explore the optical properties and vibronic transitions of LCPs; their ability of resonance energy transfer with LCPs indicating super lightning behaviour; the opposite fluorescence shift when interacting with α- helical rich polypeptides compared to earlier reports of interactions upon staining of β-rich amyloids; and the possibility of LCPs to influence protein aggregation as well as the possibility of fabricating biochips based on LCPs and soft lithography. Here we also show fundamental limitations to patterning using macromolecular fluids, of general relevance to soft lithography and nanoimprint lithography with low viscosity polymers.