Small organic molecules with structure controlled by external stimuli, e.g. photochromic dyes capable of reversibly changing their structure upon irradiation at different wavelength, are currently in the scientific focus because of their photo-controlled biological activity. On the other hand, conjugates of proteins or peptides with various oligoDNA (protein-oligoDNA conjugates, “POC”) are intensively studied due to applications in the research of molecular recognition, bioimaging, DNA nanotechnology, and development of diagnostic tests and biosensors. In the previous HrZZ project, we developed multichromophore peptides and new fluorescent dyes, some of them controlled by a photo-switch, for various bioapplications. In this proposal, we want to use previously developed knowledge and material for the design, preparation and characterization of the peptide-CONTROL TOOL-chromophore system for biorelevant targets. One researchline is focused on new photo-controlled peptide-multichromophore systems targeting various DNA, RNA, protein or cellular organelles; while the 2nd line would be based on peptide-oligoDNA(POC)-photoswitch systems with the additional feature of signal amplification by DNAzyme, by changes in the formation rate of the coloured enzyme product. Interactions of newly prepared systems with biorelevant targets (specific DNA, RNA, protein or peptide aggregate, cells and/or cell organelles) should single out the most promising biosensors or theranostic compounds