New aspects related to electrochemical performance of modified carbon paste electrodes (CPE) of high analytical performance are presented in this work. We studied whether the functionalisation of graphite powder with oxygenated functional groups (graphite oxide, GrO) could affect the electrochemical features of a classical CPE. By introducing oxygen termination over the graphite surface, a remarkable improvement in electrochemical performance was verified, including enhancement of analytical signals and charge transfer kinetics, as demonstrated from electrochemical characterisation assays conducted by cyclic voltammetry and electrochemical impedance spectroscopy towards the potassium hexacyanoferrate (II/III) probe. In addition, a positive effect was noted from the anchoring of Au nanoparticles on GrOPE. In analytical terms, two biologically relevant molecules were simultaneously determined using the proposed modified electrode based on GrO and AuNPs: epinephrine (EP) and uric acid (UA). Using differential pulse voltammetry (DPV), wide linear concentration ranges were founded for the analytical curves of EP and UA, and the limits of detection of 1.0×10−7 mol L−1 (EP) and 5.0×10−8 mol L−1 (UA) were predicted, respectively. The designed electrochemical sensor showed excellent precision of measurement and appropriate applicability for the analysis of biological fluids.

中文翻译：

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氧化石墨和金纳米颗粒作为替代材料用于设计用于同时测定生物物种的高灵敏度电化学传感器

这项工作介绍了与具有高分析性能的改性碳糊电极 (CPE) 的电化学性能相关的新方面。我们研究了具有氧化官能团（氧化石墨，GrO）的石墨粉的功能化是否会影响经典 CPE 的电化学特性。通过在石墨表面引入氧终止，证实了电化学性能的显着改善，包括分析信号和电荷转移动力学的增强，正如通过循环伏安法和电化学阻抗谱对六氰基高铁酸钾 (II/III) 进行的电化学表征分析所证明的） 探测。此外，Au 纳米粒子在 GrOPE 上的锚定也产生了积极的影响。在分析方面，使用基于 GrO 和 AuNP 的改进电极同时测定两种生物相关分子：肾上腺素 (EP) 和尿酸 (UA)。使用差分脉冲伏安法 (DPV)，EP 和 UA 的分析曲线具有较宽的线性浓度范围，检测限为 1.0×10-7 mol L-1 (EP) 和 5.0×10-8 mol L- 1 (UA) 分别被预测。所设计的电化学传感器显示出优异的测量精度和对生物体液分析的适当适用性。分别预测了 0×10-7 mol L-1 (EP) 和 5.0×10-8 mol L-1 (UA)。所设计的电化学传感器显示出优异的测量精度和对生物体液分析的适当适用性。分别预测了 0×10-7 mol L-1 (EP) 和 5.0×10-8 mol L-1 (UA)。所设计的电化学传感器显示出优异的测量精度和对生物体液分析的适当适用性。