A new electrochemical DNA biosensor based on modified carbon paste electrode using graphene quantum dots and ionic liquid for determination of topotecan

To study topotecan–DNA interaction and topotecan determination with a modified carbon paste electrode (CPE), a new electrochemical biosensor is introduced. The biosensor was prepared through modification of a CPE with ionic liquid (IL), graphene quantum dots and double stranded DNA (ds-DNA). Compared to reported conventional DNA sensors, the modified electrode displayed high sensitivity and selectivity, respectable reproducibility and satisfactory stability. Moreover, the differential-pulse voltammetric (DPV) peak current was linear to topotecan concentration in the range of 0.35–100.0 μM, with a detection limit (LOD) of 0.1 μM. Applying the proposed method to determine topotecan in blood serum and urine, the use of this screening method for analyzing real sample was studied. In general, the results indicated that this DNA biosensor could be used for the fast, simple, sensitive, and cost effective determination of topotecan in urine and serum samples. •In this study topotecan–DNA interaction was studied.•A topotecan DNA biosensor was fabricated.•Ionic liquid, graphene quantum dots and ds-DNA were used as the electrode modifiers.•The use of this biosensor for analyzing real samples was studied.