Choice of solvent for studying the role of water in ionizing radiation action on DNA

Two buffers which are commonly used in nucleic acid chemistry for maintaining the pH near neutrality are sodium phosphate and tris(hydroxymethyl)aminomethane, or Tris for short. The possible modifying action of these buffers on the sensitivity of DNA to radiation-induced strand breaks and biological inactivation has been studied. The results show that the sensitivity of the DNA is not altered by a change in concentration of sodium phosphate buffer (pH 7.1) between 0.005 M and 0.055 M, whereas the radiosensitivity of the DNA decreases when the concentration of Tris buffer (pH 8.0) is increased from 0.005 M to 0.055 M. These results indicate that sodium phosphate is a good choice of buffer for dissolving DNA samples when performing radiation studies, since the sodium phosphate itself does not seem to influence radiosensitivity.