Analytical Sciences

Abstract − Analytical Sciences, 16(5), 467 (2000).

Piezoelectric Crystal Impedance Analysis for Investigating theChanges of Interfacial Properties due to Interaction ofCobalt Salt with DNA Immobilized on Biosensor
Anhong ZHOU,* Qingji XIE,** Youyu ZHANG,** Lihua NIE,* and Shouzhuo YAO*
*College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
**Chemical Research Institute, Hunan Normal University, Changsha 410081, P. R. China
The interaction of a cobalt compound, tris(2,2'-bipyridyl)cobalt(III) perchlorate (Co(bpy)3(ClO4)3.3H2O), with DNAimmobilized on a biosensor has been investigated by using a piezoelectric impedance technique. The changes ofequivalent circuit parameters were used to characterize the changes of the interfacial properties of the piezoelectricbiosensor in the reaction system. It was found that the interaction of cobalt compound with double-strained DNA(dsDNA) could be described by a sum of two exponential functions, suggesting two corresponding kinetic steps. As fordsDNA, the change of static capacitance showed a linear correlation with time. Comparative experiments indicated thatdsDNA with double-helical structure is more easily bound with cobalt compound than single-strained DNA (ssDNA).From the frequency curve, some parameters related to this interaction, such as cross-linking ratio, binding ratio, and themaximum initial rate were roughly estimated to be 2%, 1.15, 0.72 Hz/s (or 0.12 Hz/s for ssDNA), respectively. Thelinear relationship between the frequency change and the motional resistance was verified to reflect the changes of thedensity-viscosity in the biological reaction.