Anticancer drug Dacarbazine (DCB) has been used for the treatment for metastatic malignant melanoma. In our study, the biomolecular interaction between DCB and DNA was investigated electrochemically for the first time using single-walled carbon nanotube (SWCNT) modified disposable pencil graphite electrode (PGEs). The SWCNT modified PGEs were optimized for advanced DNA sensing based on the response related to changes at the guanine oxidation signal. The oxidation signals of DCB and guanine were respectively measured before/after surface confined interaction process using differantial pulse voltammetry (DPV) in the same voltammetric scale. The experimental parameters, such as DCB concentration and interaction time of DCB with fsDNA were studied. The detection of interaction between DCB and nucleic acids was also studied via electrochemical impedance spectroscopy (EIS) and gel electrophoresis. In addition, the effect of time-dependent manner from 1min to 10min on the interaction of DCB with nucleic acids was explored upon to the changes at guanine signal of fsDNA as well as PCR samples by DPV technique.