Abstract

In this work, an electrochemical label-free DNA biosensor was developed for determination of levodopa (LD). The biosensor was constructed using reduced graphene oxide decorated with Fe₃O₄ magnetic nanoparticles (rGO–Fe₃O₄) on a carbon paste electrode (CPE) and double-stranded deoxyribonucleic acid (DNA) (DNA/rGO–Fe₃O₄-CPE). The application was related to the molecular interaction between LD and DNA. Thus, the voltammetric behavior of LD at the surface of DNA/rGO–Fe₃O₄-CPE was studied using differential pulse voltammetry (DPV) where the oxidation peak current of LD was measured as an analytical signal. A considerable increase was observed in the oxidation signal of LD at the DNA-coated electrode compared to the DNA-free electrode, indicating the pre-concentration of LD due to the interaction with the surface-confined DNA layer. Scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy confirmed the structure of the synthesized nanocomposites (electrode composition). Electrochemical studies revealed that modification of the electrode significantly increases the oxidation peak currents of LD. Under the optimum conditions, the calibration curve was linear in the range of 0.5–600 nM with a detection limit of 0.11 nM. The relative standard deviation for 200.0 nM was 4.07% (n = 5). The developed biosensor was successfully applied to the analysis of LD in human serum and urine sample.

中文翻译：

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鲑鱼精DNA和还原氧化石墨烯-Fe 3 O 4纳米复合材料修饰的碳糊电极上左旋多巴的电化学测定

摘要

在这项工作中，开发了一种无电化学标记的DNA生物传感器，用于测定左旋多巴（LD）。生物传感器由还原的氧化石墨烯构成，该氧化石墨烯在碳糊电极（CPE）上装饰有Fe ₃ O ₄磁性纳米颗粒（rGO–Fe ₃ O ₄）和双链脱氧核糖核酸（DNA）（DNA / rGO–Fe ₃ O ₄ -CPE）。该应用与LD与DNA之间的分子相互作用有关。因此，LD在DNA / rGO–Fe ₃ O ₄表面的伏安行为使用差动脉冲伏安法（DPV）研究了-CPE，其中测量了LD的氧化峰值电流作为分析信号。与不含DNA的电极相比，在DNA涂覆的电极上观察到LD的氧化信号显着增加，这表明由于与表面受限的DNA层的相互作用，LD的预浓缩。扫描电子显微镜，能量色散X射线和傅立叶变换红外光谱证实了合成的纳米复合材料的结构（电极组成）。电化学研究表明，电极的修饰显着增加了LD的氧化峰值电流。在最佳条件下，校准曲线在0.5–600 nM范围内呈线性，检出限为0.11 nM。200.0 nM的相对标准偏差为4.07％（n = 5）。研制成功的生物传感器已成功应用于人血清和尿液样品中LD的分析。