Study of the effect of argon glow discharge irradiation on the conformation of DNA molecules using laser spectroscopy methods

Abstract

The aim of this work is to study the photochemical processes of hydrolysis of biomacromolecules, using the example of DNA in DNA and DNA-Polyethylene glycol (model of nucleoprotein) solutions. The processes induced by the line spectrum of an argon glow discharge lamp (AGDL) (700–1800 nm, 1.7–0.7 eV) have been studied by spectrophotometry, light scattering, turbidimetry, and spectrofluorimetry. It is shown that acridine orange (AO) intercalated in DNA is a good indicator of pH, i.e. of the presence of H3O+ ions in DNA solutions. H3O+ ions quench AO fluorescence and, in addition, eject it from the DNA in the solution. Using the methods of laser spectroscopy (light scattering, fluorescence, and resonance energy transfer) and spectrophotometry, we have observed hydrolysis of water solutions and of glycosidic and phosphodiester bonds in DNA and DNA-polyethylene glycol water solutions induced by near-infrared (700–1800 nm, (AGDL)) irradiation. The method is based on the difference between cancer and healthy cells because a normal cell has a perfect DNA repair system that makes near-infrared photo-irradiation non-invasive for them and lethal for a cancer cell. Using the turbidimetry method, the average size of the DNA aggregates from the calf thymus in a 150 mg ml−1 polyethylene glycol solution was determined and it is 250 nm in approximation that the aggregate has a spherical form. Aggregated DNA macromolecules are in B-form and the aggregate contains 12 · 106 b.p.