Supramolecular complexes of biopolymers based on magnetic nanoparticles play an important role in creation of biosensors, implementation of theragnos- tic and gene therapeutic methods and biosafety evalu- ation. We investigated the impact of DNA interactions with nanoparticles of nickel (nNi) on the integrity and functionality of DNA. Data obtained by mass spec- trometry, electrophoresis, TEM and AFM microscopy techniques, bacterial transformation, and real-time PCR provide evidence that ssDNA and plasmid DNA (pDNA) efficiently form complexes with nNi. AFM data suggest that the complexes are necklace-type structures, in which nanoparticles are randomly distrib- uted along the DNA chains, rather than highly entangled clot-type structures. After desorption, observed DNA characteristics in bioanalytical and biological systems remain unchanged. Only supercoiled pDNA was nicked, but remained, as well as a plasmid-nNi complex, active in expression vector assays. These results are very important for creation of new methods of DNA immobilization and controlled manipulation.