Previous workers have shown that high magnetic fields cause morphological changesin DNA at high concentration where it exists as the liquid crystal cholesteric phase.The aim of the present work was to identify corresponding changes in the dielectricproperties of DNA in the frequency range 20 Hz to 300 kHz, at lower magnetic fieldintensity and lower concentrations.Investigations were carried out with DNA solution on interdigitated electrodes,where the magnetic field was applied perpendicular to the electric field. Evidencewas found of reversible changes in the dielectric properties caused by magnetic fieldslower than 0.7 Tesla at high concentrations (∼170 mg/ml). Using planar electrodes,where the magnetic field was applied parallel to the electric field, reversible changesin dielectric properties due to magnetic fields of lower than 0.7 Tesla were foundin DNA solutions at lower concentrations (25−100 mg/ml). Replacement of thesodium in the DNA with other cations by dialysis produced similar results, thoughthe frequencies of the responses also varied with the cations used.
A method was developed using Matlab’s Genetic Algorithm toolbox to analyse thedifferencebetween loss spectra caused by changes in one dispersion. The methodwas able to extract the parameters of the dispersion before and after application ofthe magnetic field. Changes in these parameters with concentration, temperature,additional sodium chloride, and applied a.c.voltage are reported. Changes with tem-perature indicate that an Arrhenius-type process is responsible for the dispersion.Evidence was presented that the dispersion found to be susceptible to magnetic fieldwas caused by relaxation of the counter-ions in the condensed phase surroundingthe DNA chain.