Kinetics of ion-exchange binding of redox metal cations to thiolate-DNA monolayers on gold

The ion-exchange kinetics of metal cation binding to and dissociation from thiolate-DNA monolayers on gold can be monitored by a simple electrochemical protocol. The apparent first-order rate constants were obtained by analyzing the time-dependent voltammetric behavior of the redox cation [Ru(NH3)(6)](3+). It was found that the binding kinetics is dominated by the structural nature of the film; i.e., the apparent first-order rate constant (k(app)) decreases significantly upon increasing the surface density of DNA strands. Dissociation rate constants were obtained by transferring the incubated electrode into redox-free buffer solution. The kinetic data augment our fundamental understanding of metal ion-DNA interactions and are critical to ensure the accuracy and reliability of experimental DNA detection protocols.