组成图示
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传感器类型
电化学生物传感器
检测对象
多巴胺（dopamine, DA）、抗坏血酸/维生素C（ascorbic acid, AA）、尿酸（uric acid, UA）；样品基质：0.1 M KHP缓冲液（pH 4.0）、多巴胺注射液、维生素C片、人尿。
检测原理
在pH 4.0的KHP缓冲液中，DA、AA和UA扩散至PtAu混合膜修饰的GC电极表面。Pt颗粒和nanoAu颗粒提供高比表面积与活性位点，降低三种物质的氧化过电位并促进电子转移；Au的氧化态还可介导DA、AA和UA的氧化。由于PtAu膜的多价态催化作用，原本在裸电极上重叠的阳极峰被分离为AA、DA和UA三个清晰峰，峰电位分别约为0.20–0.25 V、0.35–0.37 V和0.52–0.54 V（vs Ag/AgCl）。被测物浓度升高时，界面氧化反应速率和电子转移量增加，CV或DPV阳极峰电流随之线性增大，从而通过峰电流定量。
检测灵敏度
LOD: 0.103, 0.024 and 0.021 mM (原文: lower limit of detection of AA, DA and UA was estimated to be in the order of 0.103, 0.024 and 0.021 mM respectively)；线性范围(DPV): AA 0.103–1.65 mM, DA 0.024–0.384 mM, UA 0.021–0.336 mM；线性范围(CV): AA 0.069–1.384 mM, DA 0.022–0.44 mM, UA 0.062–2.499 mM；灵敏度斜率: 0.0083, 0.05 and 0.0152 μA μM−1 for AA, DA and UA；R^2 = 0.9906, 0.9983 and 0.9875。
效应效果
PtAu膜将DA、AA和UA重叠峰解析为三个分离峰，三者之间无明显干扰；在高浓度AA存在下仍可测定DA和UA，在高浓度UA存在下仍可测定AA和DA。DPV重现性良好，AA（1.65 mM）、DA（0.384 mM）和UA（0.336 mM）的RSD分别为1.363%、1.207%和1.88%（n=10）。实际样品加标回收率为：多巴胺注射液94.8–105.0%，维生素C片94.20–103.33%，人尿95.16–102.0%。与文献修饰电极相比，该电极峰电位为0.20、0.35和0.54 V，适用于生物样品中DA、AA和UA的同时测定。
传感器的构成
- 基底/换能器电极：玻碳电极（GC），作为工作电极与电子传导基底；金电极/ITO用于EQCM、SEM、AFM和XRD表征。
- 纳米材料修饰层：PtAu混合膜，由K2PtCl6、KAuCl4·3H2O在0.5 M H2SO4中电沉积形成，提供电催化活性位点。
- 颗粒组成：Pt颗粒（200–300 nm）与nanoAu颗粒（50–80 nm）共沉积单层膜，降低过电位并分离氧化峰。
- 成膜助剂：L-半胱氨酸（L-Cys，100 μM），促进Pt和nanoAu颗粒稳定附着并形成混合膜。
- 识别元件：无特异性生物识别元件，直接利用PtAu膜对DA、AA、UA的电催化氧化实现检测。
- 电解液/介质：0.1 M KHP缓冲液（pH 4.0），提供反应介质并维持pH。
- 信号标记物：无外源标记物，氧化电流直接作为检测信号。
中文摘要
本文通过循环伏安电沉积法，在玻碳电极表面制备了由铂颗粒、金纳米颗粒（nanoAu）和L-半胱氨酸组成的PtAu混合膜修饰电极。SEM、AFM和XRD表明nanoAu粒径为50–80 nm，Pt粒径为200–300 nm；该混合膜也可沉积于金电极和透明ITO电极，用于电化学石英晶体微天平（EQCM）、扫描电镜、原子力显微镜、X射线衍射及电化学研究。在pH 4.0的KHP缓冲液中，PtAu膜对多巴胺（DA）、抗坏血酸（AA）和尿酸（UA）的电催化氧化表现出良好活性，循环伏安（CV）和差分脉冲伏安（DPV）将三者重叠的阳极峰解析为三个清晰峰。峰电流随浓度线性增加，AA、DA和UA的相对标准偏差（n=10）小于2.0%。DPV下AA、DA和UA的测定范围分别为0.103–1.65、0.024–0.384和0.021–0.336 mM。该电极还用于多巴胺注射液、维生素C片和人尿样品中DA、AA和UA的测定，结果令人满意。
英文摘要
A novel biosensor was fabricated by electrochemical deposition of platinum and gold nanoparticles (nanoAu) with l-Cysteine on glassy carbon electrode. It was found that the nanoAu particle size distribution range was (50-80 nm), and the platinum particle size range was (200-300 nm). The hybrid film could be produced on gold and transparent indium tin oxide electrodes for different kind of studies such as electrochemical quartz crystal microbalance (EQCM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) and electrochemical studies. The PtAu hybrid film was applied to the electro catalytic oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) at pH 4.0 using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode was quite effective not only to detect DA, AA and UA individually but also in simultaneous determination of these species in a mixture. The overlapping anodic peaks of DA, AA and UA were resolved into three well-defined voltammetric peaks in CV and DPV. The catalytic peak currents obtained from CV and DPV increased linearly with concentration. The relative standard deviation (% R.S.D., n=10) for AA, DA and UA were less than 2.0% and DA, AA and UA can be determined in the ranges of 0.103-1.65, 0.024-0.384 and 0.021-0.336 mM, respectively. In addition, the modified electrode also shows good sensitivity, and stability. Satisfactory results were achieved for the determination of DA, AA and UA in dopamine injection solution, vitamin C tablets and human urine samples.