Cross-linking of DNA monolayers by cisplatin examined using electrostatic denaturation

Abstract

This paper reports on the electrostatic denaturation of double-stranded DNA monolayers in the presence of anti-cancer drug cis-Diamminedichloroplatinum(II) (cisplatin). Cisplatin binds DNA at purine bases, effecting its thermal stability and melting temperature. Here we show for the first time how cisplatin effects the stability of DNA monolayers in the presence of high electric fields generated at the electrode/solution interface, and how this behavior is effected by the method of monolayer preparation. A slight decrease in melting rate and a large decrease in the extent of melting are observed for electrodes prepared with methods that produce homogeneous DNA surface coverage where interstrand distances are maximized. On the other hand, heterogeneous and densely-packed monolayers are found to melt much slower and to a slightly greater extent with bound cisplatin. Three procedures for preparation of the mercaptohexanol/DNA mixed monolayers are compared, demonstrating the potential application of cisplatin, along with electrostatic denaturation analysis, to interrogate surface density and surface heterogeneity in self-assembled DNA monolayers.