▎ 摘　　要

PAMAM dendrimer/reduced graphene oxide nanocomposite modified pencil graphite electrode (PAMAM/RGO/PGE) was used to fabricate an electrochemical DNA biosensor for determination of Rituxan (RTX) at low concentrations, for the first time. The fabricated biosensor was characterized with FE-SEM, EIS, and CV techniques. The ds-DNA/PAMAM/RGO/PGE was used as a working electrode to study the interaction between the RTX and salmon sperm ds-DNA by DPV technique. Because of the interaction between the drug and DNA leads to a decrease in the guanine oxidation peak current, it was used as an indicator for the determination of the RTX. Under the optimized experimental conditions, a widelinear relationshipbetween RTX concentration and guanine signal was obtained within the range of 7.0 to 60.0molL(-1) and 60.0 to 300.0molL(-1) with a low detection limit (0.56molL(-1)). To clarify the interaction mechanism between the RTX and the ds-DNA, DPV and UV-Vis measurements were used. The reproducibility, stability, and performance of the constructedbiosensor was examined by quantitative measuring RTX in pharmaceutical and human serum samples with good precision (RSD; 2.0-6.0%) and acceptable recoveries (100.04-101.95%).