Electrochemical investigation of the interaction between topotecan and DNA at disposable graphite electrodes

• TPT–DNA interaction was investigated based on the changes at TPT and guanine signals.
• The LODs of TPT were obtained as 0.51 and 0.37 μg/mL by PGEs and SWCNT–PGEs.
• After TPT–dsDNA interaction, there was a decrease at Rct obtained by EIS technique.
• TPT–DNA interaction was investigated for the first time herein by using DPV and EIS techniques.

Topotecan (TPT) is a semisynthetic, water soluble analog of the plant alkaloid camptothecin which has been widely used for the treatment of ovarian and cervical cancers. To obtain better understanding on how it can affect DNA structure, electrochemical biosensor platforms for the investigation of TPT-double stranded DNA (dsDNA) interaction were developed for the first time in this study. The electrochemical detection of TPT, and TPT–dsDNA interaction were investigated at the surface of pencil graphite electrodes (PGEs) and single-walled carbon nanotube (SWCNT) modified PGEs by using differential pulse voltammetry (DPV). The changes at the oxidation signals of TPT and guanine were evaluated before/after each modification/immobilization step. An enhanced sensor response was obtained by using SWCNT–PGEs compared to unmodified PGEs with resulting limits of detection (LODs) for TPT as 0.51 μg/mL, 0.45 μg/mL, 0.37 μg/mL (130 pmol, 117 pmol, 96.5 pmol in a 110 μL sample, respectively) by using electrochemically pretreated PGE, unmodified PGE and SWCNT modified PGE. In addition, electrochemical impedance spectroscopy (EIS) measurements were performed for the purpose of modification of PGEs by using SWCNTs and the interaction process at the surface of SWCNT–PGEs by evaluating the changes at the charge transfer resistance (Rct).

Figure optionsDownload as PowerPoint slide