A thiolated catechol (CA) consisting of 1,6-Hexanedithiol (HDT) and CA was modified on a gold (Au) electrode to obtain an amperometric L-cysteine sensor with detection limit of 60.6 nM. The preparation of thiolated CA was conducted via a thiol addition between HDT and electro-oxidized CA (EOCA). Briefly, the thiol addition reaction was accomplished by potential cycling of HDT/Au electrode in 0.1 M phosphate buffer (PB, pH 7.2) containing CA, and an EOCA-HDT/Au electrode was produced. The obtained EOCA-HDT/Au electrode exhibits a pair of well-defined redox peaks (at 0.22/0.10 V) of o-quinone moiety, which effectively mediates the oxidation of L-cysteine in a 0.1 M PB (pH 7.2), with an over-potential decrease by ca. 0.12 V (versus bare Au electrode). Electrochemical quartz crystal microbalance, cyclic voltammetry and surface-enhanced Raman spectra were used to study relevant processes and/or film properties. The amperometric L-cysteine sensor has good anti-interferent ability and reproducibility. It also has acceptable recovery for detection of L-cysteine in urine samples.

中文翻译：

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使用硫醇邻苯二酚修饰的金电极的电流型 L-半胱氨酸传感器

由 1,6-己二硫醇 (HDT) 和 CA 组成的硫醇化儿茶酚 (CA) 在金 (Au) 电极上进行修饰，以获得检测限为 60.6 nM 的安培 L-半胱氨酸传感器。硫醇化 CA 的制备是通过 HDT 和电氧化 CA (EOCA) 之间的硫醇加成来进行的。简而言之，硫醇加成反应是通过 HDT/Au 电极在含有 CA 的 0.1 M 磷酸盐缓冲液（PB，pH 7.2）中的电位循环来完成的，并产生了 EOCA-HDT/Au 电极。获得的 EOCA-HDT/Au 电极表现出一对明确定义的 o-醌部分的氧化还原峰（在 0.22/0.10 V），它有效地介导了 0.1 M PB（pH 7.2）中 L-半胱氨酸的氧化，与过电位减少约。0.12 V（相对于裸金电极）。电化学石英晶体微量天平，循环伏安法和表面增强拉曼光谱用于研究相关过程和/或薄膜特性。电流型L-半胱氨酸传感器具有良好的抗干扰能力和重现性。它还具有检测尿样中 L-半胱氨酸的可接受回收率。