Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (10): 2258-2262.doi: 10.3866/PKU.WHXB201208281

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Influence of Ionic Strength on DNA Mediated Charge Transport——Experiments and the Related Debye-Hückel Theory

JI Zhong-Hua1, ZHU Bin1, LI Jing-Jian1, CAI Sheng-Min1, YUAN Gu2, XU Dong-Sheng1   

  1. 1 Beijing National Laboratory for Molecular Sciences, Institute of Physical Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China;
    2 Department of Chemical Biology, The Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2012-08-01 Revised:2012-08-27 Published:2012-09-26
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20573008).


The ionic strength dependence of DNA mediated charge transport was studied on a DNA binding polyamide-modified electrode by the electrochemical method. The differential pulse voltammetry (DPV) peak potential of [Ru(NH3)6]3+ shifted negatively with the increase of support electrolyte concentration. Linear relationship between peak potential and ionic strength in the solution was found at the range of moderate salt concentration, which can be interpreted with Debye-Hückel theory using formal potential as a “bridge” linked experiments results and theoretical calculated values. Under high salt concentration this linear relationship deviated from Debye-Hückel theory prediction due to its range of validity is overstep. Without added salt in the solution, fully charged DNA duplex will strongly attract the probe molecule [Ru(NH3)6]3+ to the broadened p-stack of a DNA-polyamide complex, which facilitated DNA mediated charge transport.

Key words: Ionic strength, Debye-Hü, ckel theory, DNA minor groove, Broadened π-stack