PhD thesis on "Synthesis and studies of modified DNA: (i) development of DNA targeting molecular scissors and (ii) competitive enzymatic incorporation of base-modified nucleotides", under the supervision of Prof. Michal Hocek.The project mainly aimed to the development of site-specific artificial metallonuclease cutters of DNA, based on conjugates of triplex-forming oligonucleotides and Cu complexes of phenanthroline ligands.The project was part of the Marie-Curie “ClickGene” network, and included a one-month secondment in Prof. Tom Brown group, at the University of Oxford, Oxford, UK, and a one-month secondment in Andrew Kellett group, at the Dublin city University, Dublin, Ireland.