Oxytocin (OXY), a peptide hormone and neurotransmitter essential for biological processes with nine distinct amino acid residues, has received significant attention due to its illegal use in food adulteration and stimulating milk ejection in cattle. Herein, for the first time, electrochemical detection of oxytocin (OXY) is reported using a novel nanocomposite consisting of a Zn–Cu metal–organic framework (Zn–Cu MOF) decorated on reduced graphene oxide (rGO). An octahedral surface morphology with a crystalline structure of 45 nm in size, formation of a metal–oxygen bond, an enhanced pore diameter of 6.8 nm, a specific surface area of 70.8 m² g⁻¹, and a pore volume of 0.08 cm³ g⁻¹ were revealed by different characterization techniques. The electro-catalytic activity of the Zn–Cu MOF/rGO nanocomposite increased substantially owing to the synergistic effect, which is evident from cyclic voltammetry (CV) when compared to those of the Zn-MOF, the Cu-MOF, Zn MOF/rGO, Cu MOF/rGO, and Zn–Cu MOF, keeping other parameters the same. Moreover, the electrochemical impedance spectroscopy (EIS) spectra reveal the excellent conductivity of the nanocomposite. The experimental parameters, viz. electrolyte pH (5), supporting electrolyte (0.1 M ABS), and volume of coating (12 μL), were optimized. The differential pulse voltammetry (DPV) technique was adopted to determine the OXY with the lowest limit of detection (LOD) of 1.1 nM (S/N = 3) with a linear range of 40–400 nM. The analytical application of the modified electrode was examined by spiking OXY in pasteurized toned milk, skimmed powder milk, animal milk, and RO water, with a good recovery range of 95–106%.

中文翻译：

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调节 Zn-Cu MOF/rGO 纳米复合材料作为新型无酶电化学传感器检测催产素激素的电催化活性


催产素 （OXY） 是一种对生物过程至关重要的肽激素和神经递质，具有 9 个不同的氨基酸残基，由于其非法用于食品掺假和刺激牛的乳汁喷射而受到广泛关注。在此，首次报道了使用一种新型纳米复合材料对催产素 （OXY） 进行电化学检测，该复合材料由装饰在还原氧化石墨烯 （rGO） 上的 Zn-Cu 金属-有机框架 （Zn-Cu MOF） 组成。通过不同的表征技术揭示了具有 45 nm 晶体结构、金属-氧键形成、6.8 nm 增强孔径、70.8 m^{2 g-1} 比表面积和 0.08 cm^{3 g-1} 孔体积的八面体表面形态。由于协同效应，Zn-Cu MOF/rGO 纳米复合材料的电催化活性显着增加，这与 Zn-MOF、Cu-MOF、Zn MOF/rGO、Cu MOF/rGO 和 Zn-Cu MOF 相比，循环伏安法 （CV） 可以明显证明，同时保持其他参数相同。此外，电化学阻抗谱 （EIS） 光谱揭示了纳米复合材料的优异导电性。优化了实验参数，即电解质 pH 值 （5）、支持电解质 （0.1 M ABS） 和涂层体积 （12 μL）。采用差分脉冲伏安法 （DPV） 技术测定 OXY，最低检测限 （LOD） 为 1.1 nM （S/N = 3），线性范围为 40–400 nM。通过在巴氏杀菌调色牛奶、脱脂奶粉、动物奶和 RO 水中加标 OXY 来检查改性电极的分析应用，具有良好的 95-106% 的回收范围。