Abstract The optimal conditions for fabricating a screen-printed diamond electrode for the sensitive detection of L-cysteine (Cys), a non-essential amino acid, were investigated. As-grown (AG-), hydrogen-terminated (H-) and oxygen-terminated boron-doped diamond powders (O-BDDP) were prepared, and BDDP-printed electrodes were fabricated using BDDP-containing inks. Comparing the linear sweep voltammograms of Cys at AG-BDDP-, H-BDDP-, and O-BDDP-printed electrodes, among the three samples, the H-BDDP-printed electrode was found to be the most suitable for the sensitive detection of Cys at low concentrations, showing a steep slope in its calibration curve and a low background current density. In addition, the H-BDDP-printed electrode exhibited a lower limit of detection (0.617 μM) and a more negative oxidation peak potential (+0.663 V vs. Ag/AgCl) and wider linear concentration range (1–194 μM) than a H-boron-doped diamond (BDD) thin-film electrode. It is thought that a slight amount of sp2 carbon on the BDDP contributed to these optimal properties. Using the H-BDDP-printed electrode, Cys was detected in a solution containing electroactive interferents (glutathione and methionine) with a recovery of 86–104%. Therefore, it was concluded that the H-BDDP-printed electrode can be used as a highly sensitive and disposable electrochemical sensor for Cys detection.

中文翻译：

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L-半胱氨酸在丝网印刷金刚石电极上的灵敏电化学检测

摘要 研究了制备用于灵敏检测非必需氨基酸 L-半胱氨酸 (Cys) 的丝网印刷金刚石电极的最佳条件。制备了生长态 (AG-)、氢封端 (H-) 和氧封端的掺硼金刚石粉末 (O-BDDP)，并使用含 BDDP 的墨水制造了 BDDP 印刷电极。比较 AG-BDDP-、H-BDDP- 和 O-BDDP 印刷电极上 Cys 的线性扫描伏安图，在三个样品中，发现 H-BDDP 印刷电极最适合于敏感检测低浓度的 Cys，显示其校准曲线的陡峭斜率和低背景电流密度。此外，H-BDDP 印刷电极表现出检测下限（0.617 μM）和更负的氧化峰电位（+0.663 V vs. Ag/AgCl) 和比掺氢金刚石 (BDD) 薄膜电极更宽的线性浓度范围 (1–194 μM)。据认为，BDDP 上的少量 sp2 碳有助于这些最佳性能。使用 H-BDDP 印刷电极，在含有电活性干扰物（谷胱甘肽和甲硫氨酸）的溶液中检测到 Cys，回收率为 86-104%。因此，得出的结论是，H-BDDP 印刷电极可用作高灵敏度和一次性电化学传感器，用于 Cys 检测。在含有电活性干扰物（谷胱甘肽和蛋氨酸）的溶液中检测到半胱氨酸，回收率为 86-104%。因此，得出的结论是，H-BDDP 印刷电极可用作高灵敏度和一次性电化学传感器，用于 Cys 检测。在含有电活性干扰物（谷胱甘肽和蛋氨酸）的溶液中检测到半胱氨酸，回收率为 86-104%。因此，得出的结论是，H-BDDP 印刷电极可用作高灵敏度和一次性电化学传感器，用于 Cys 检测。