Nanobiotechnology for health-care

Blocking DNA activity on the nano-scale in ion beam therapy of cancer cells
Volkov S.N.
Laboratory of Biophysics of Macromolecules, Bogolyubov Institute for Theoretical Physics, NAS of Ukraine. Metrologichna Str. 14-b, 03143 Kiev, Ukraine.
E-mail: snvolkov@bitp.kiev.ua

A progressive method of malignant tumors treatment is the radiation therapy. The mechanisms of treatment here are associated with the formation of reactive products of water radiolysis, which can destroy the DNA macromolecule in cells. But during the radiolysis another important process is the formation of long-lived molecular products, such as hydrogen peroxide (H2O2) molecules.  In ion beam therapy these molecules can accumulate in the cell medium upon irradiation and play an important role in the blocking of DNA activity on the nano-scale in tumor. However, the role of H2O2 molecules in cancer treatment has not been determined yet. In present work the competitive binding of H2O2 and H2O molecules with the atomic groups of DNA is under consideration.
Using the approaches of atomic potential functions and density functional theory, spatial configurations and possibility to form the stable complexes of H2O2 and H2O molecules with DNA atomic groups responsible for the recognition with proteins are studied. The most probable positions of peroxide and water molecules in the complexes with nucleic bases (specific recognition sites) and backbone phosphate groups (nonspecific recognition sites) are found. The formation energy of these complexes demonstrates the advantage of H2O2 over H2O in all analyzed cases [1–4].
The forming of stable complexes of DNA atomic groups with H2O2 molecules should lead to DNA activity blocking on the nanoscale, and can be one of the important stages of genetic apparatus deactivation in the treatment of cancer. Experimental observations of DNA activity blocking by H2O2 and the possible effects of these molecules on DNA biological functioning will be discussed.

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2.	D.V. Piatnytskyi, S.N. Volkov, Biophysical Bulletin, 39 (1), 5-14 (2018).
3.	 O.O. Zdorevskyi, S.N. Volkov, submitted to UJP (2019). 
4.	O.O. Zdorevskyi, D.V. Piatnytskyi, S.N. Volkov, Proc. NASU, №7 (2019).