Dielectric behavior of DNA solution at radio and microwave frequencies (at 20 degrees C)

Abstract

The dielectric constant and conductivity of calf thymus DNA were investigated at frequencies between 0.1 MHz and 70 GHz. This work is to investigate the dielectric properties of DNA in low gigahertz region and also to study whether the dielectric behavior of the water is affected by the presence of highly charged DNA. The results of these measurements indicate the presence of two anomalous dispersions, the one between 1 MHz and 1 GHz and the second one above 1 GHZ. The dispersion at low frequencies is likely to arise from polar groups in the DNA molecule. The relaxation behavior of unbound water in DNA solution is only slightly affected by the presence of DNA at concentrations below 1%.

Dielectric behaviour of frozen DNA in solution

“…This observed dielectric behaviour was confirmed independently by Anagnostopoulou-Konsta et al [1988], who resolved two dispersions in DNA solutions using the method of thermally stimulated depolarization currents (TSDC), and more recently by Bone et al [1996] from dielectric data in the frequency range 10 -100 MHz. Two particularly interesting features of the small disper- sion are the very high activation energy (86 Ϯ 12 kJ/mole) and the fact that Figure 7 when extrapolated to T ϭ 293 K predicts a relaxation frequency of between 80 -90 MHz, as observed in the previous work [Takashima et al, 1984] carried out at 20 ºC. In other words, this dispersion preserves its characteristics through the change of state; freezing the substance does not apparently have any effect.…”

“…The pH was adjusted to 7.0 using Tris buffer. This method of sample preparation was used in order to correspond with that of Takashima et al [1984] at 20 ºC, so that direct comparison could be made. The complex permittivity measurements were made using a Hewlett Packard model 4192A impedance analyser, using a previously described technique [Bateman et al, 1992].…”

“…Previous work by Takashima et al [1984] on calf thymus DNA had been carried out using measuring equipment spanning a frequency range 0.1 MHz -70 GHz. Aqueous solutions of concentration around 1% were measured at 20 ºC.…”

Ultralocalized thermal reactions in subnanoliter droplets-in-air

“…Previous studies have also shown that DNA-in-water solutions have a strong relaxation point in the low MHz regime (32,33). This is typically considered to be due to counter ion movement around the transverse axis of the DNA molecule (34)(35)(36). Using 10 MHz and the movement of ions around the DNA molecule allows heating of a DNA-inwater solution at a much lower frequency than a traditional microwave heater.…”

Electrical properties and dielectric relaxaction of DNA in solution

“…The measurements can be divided between those studies that measured DNA above 1 MHz and those studies that measured at low frequencies (< 1000 Hz). Higher-frequency measurements were made by a number of authors [40,[89][90][91][92]. Low-frequency measurements have been made by Takashima, Sakamoto, Hanss, and Tung [16,20,32,93].…”