In this work an electrochemical label free DNA biosensor (ds-DNA) for the determination of menadione (MD) was developed. The biosensor was constructed using a modified nanocomposite consisting of Fe₃O₄ nanoparticles decorated reduced graphene oxide (Gr) on a carbon paste electrode (CPE). Scanning electron microscope (SEM), energy dispersive X-ray (EDAX) and Fourier transform infrared (FT-IR) spectroscopy confirmed the structure of the synthesized nanocomposites (electrode composition). The Gr-Fe₃O₄ nanocomposites formed a sensitive layer with large surface area. Electrochemical studies revealed that modification of the electrode surface with ds-DNA and Gr- Fe₃O₄ nanocomposite significantly increases the oxidation peak currents and reduces the peak potentials of MD. Under the optimum conditions, calibration curve was linear in the range of 0.3–100.0 nM with a detection limit of 0.13 nM. The relative standard deviation for 50.0 nM was 3.90% (n = 5). The proposed biosensor was successfully applied to the determination of MD.

在这项工作中，开发了用于测定甲萘醌（MD）的无电化学标记的DNA生物传感器（ds-DNA）。使用修饰的纳米复合材料构建生物传感器，该复合材料由在碳糊电极（CPE）上装饰有还原性氧化石墨烯（Gr）的Fe ₃ O ₄纳米颗粒组成。扫描电子显微镜（SEM），能量色散X射线（EDAX）和傅里叶变换红外（FT-IR）光谱证实了合成的纳米复合材料的结构（电极组成）。Gr-Fe ₃ O ₄纳米复合材料形成具有大表面积的敏感层。电化学研究表明，用ds-DNA和Gr-Fe ₃ O ₄修饰电极表面纳米复合材料显着增加了氧化峰值电流并降低了MD的峰值电势。在最佳条件下，校正曲线在0.3-100.0 nM范围内呈线性，检出限为0.13 nM。50.0 nM的相对标准偏差为3.90％（n  = 5）。提出的生物传感器已成功应用于MD的测定。