Nanophotonics and DNA: New approaches
  The aim of the present work is spectroscopic and thermodynamic study of DNA catalytic properties in the following processes: a) redox; b) formation of inter-strand cross-links; c) performing of photo-dynamic effects; d) nanoscale resonance radiationless electron excitation energy transfer. The most attention is paid to the latter, as truly nanoscale method in its origin. The nanoscale method of laser induced fluorescence resonance energy transfer (FRET) to donor (acridine orange) - acceptor (ethidium bromide) intercalator pair for quantitative and qualitative study of stability quality DNA double helix in solution in real time is offered. FRET method allows to estimate the concentration of double helix areas with high quality stability applicable for intercalation in DNA after it was subjected to stress effect. It gives the opportunity to compare various types of DNAs with 1) different origin; 2) various damage degrees; 3) being in various functional state. Alternative model and mechanisms of photodynamic effect on DNA in solutions are proposed. They are based on photoenergy degradation in solutions. The energy activates electrolytic dissociation of water molecules on H3O+ and OH- and acts as a catalyst for hydrolyse reactions of phosphordiester and glycoside linkages. 
Vasil G. Bregadze, Zaza G. Melikishvili, Tamar G. Giorgadze
physics.bio-ph