Temperature dependence of capacitance on DNA solutions

We have measured the temperature dependence of the capacitance on the poly(dA), poly(dA)–poly(dT), and DNA solutions with both A–T and G–C base pairs to investigate the relation between the capacitance and the DNA structure. As the temperature increases, the capacitance of the single-stranded DNA solution increases, whereas that of the double-stranded one decreases with increasing the temperature and exhibits an upturn when DNA molecules are denatured. Moreover, the temperature dependence of the capacitance is found to be different depending on the DNA sequence. These results suggest that the conformational change of DNA molecules can be detected through the capacitance measurements that do not require any labeling and immobilization on a solid support.