Study on the interactions between anti-cancer drug oxaliplatin and DNA by atomic force microscopy

•AFM topographic image pUC19 DNA on HOPG surface has been characterized.•Structural features of pUC19 DNA with low concentration of oxaliplatin were studied.•Structural features of pUC19 DNA with high concentration of oxaliplatin were studied.•Platination process of pUC19DNA induced by the activated oxaliplatin was proposed.

Oxaliplatin is one of the most important anticancer drugs at present. However, the mechanism of action of oxaliplatin is still controversial. In this study, the interactions between oxaliplatin and a plasmid DNA have been studied so as to reveal the structural basis of its activity. The structural characteristic of pUC19 DNA (2 ng/μL) incubated with 100 μmol/L and 1000 μmol/L of oxaliplatin for the different time on a freshly cleaved highly ordered pyrolytic graphite (HOPG) surface was investigated by atomic force microscopy (AFM). High resolution AFM observation indicated that oxaliplatin can induce pUC19 DNA molecules change from the extended conformation to the entangled structures with many nodes, and finally to the compact particles. The present AFM results provide structural evidence about the interactions between oxaliplatin and circular duplex DNA containing multiple targets.