The method for registration of a single DNA molecule length change during interaction with a ligand is proposed. The method is tested in the case of DNA molecule interaction with intercalating YOYO-1 dye. The experimental data obtained signifies both DNA elongation and mechanical properties alteration upon YOYO-1 binding.
The proposed method can be used to study single DNA molecule interaction with different ligands, including dyes and DNA-binding proteins. Also this method can be used to study other biopolymers, including amyloid fibrils.