In this work, PtCo bimetallic nanoparticles supported on multi-walled carbon nanotubes (PtCo@MWCNTs) nanohybrid was prepared simply and used for the first time as a novel nanozyme in the colorimetric sensing of L-cysteine (L-Cys) and Cu2+. Due to its strong enzyme-like catalytic activity, the prepared PtCo@MWCNTs nanohybrid can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to form ox-TMB without H2O2. Interestingly, the oxidase-like active of PtCo@MWCNTs was effectively suppressed by L-Cys, which could reduce ox-TMB to colorless TMB and lead to a pronounced blue fading, and the absorbance at 652 nm gradually decreased with increasing L-Cys concentration. On the other hand, the nanozyme activity of PtCo@MWCNTs can be recovered due to the complexation between L-Cys and Cu2+. Therefore, a colorimetric method based on PtCo@MWCNTs nanozyme was established to detect L-Cys and Cu2+. The results show that the assay platform has simple, rapid, sensitive performance and good selectivity. The detection limits for L-Cys and Cu2+ are 0.041 μM and 0.056 μM, respectively, coupled with the linearities of 0.01 ~ 60.0 μM and 0.05 ~ 80.0 μM. The successful first application of PtCo bimetal-based nanozyme in colorimetric sensing herein opens a new direction for nanozyme and colorimetric analysis, showing great potential applications.

中文翻译：

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基于 PtCo 纳米粒子@多壁碳纳米管的 L-半胱氨酸和铜离子的纳米酶比色传感。

在这项工作中，简单地制备了多壁碳纳米管负载的PtCo双金属纳米粒子（PtCo@MWCNTs）纳米杂化物，并首次作为新型纳米酶用于L-半胱氨酸（L-Cys）和Cu2+的比色传感。由于其强大的类酶催化活性，所制备的PtCo@MWCNTs纳米杂化物可以在没有H2O2的情况下催化3,3',5,5'-四甲基联苯胺（TMB）氧化形成ox-TMB。有趣的是，PtCo@MWCNTs的类氧化酶活性被L-Cys有效抑制，可以将ox-TMB还原为无色TMB并导致明显的蓝色褪色，并且随着L-Cys浓度的增加，652 nm处的吸光度逐渐降低。另一方面，由于L-Cys和Cu2+之间的络合，PtCo@MWCNTs的纳米酶活性可以恢复。因此，建立了一种基于PtCo@MWCNTs纳米酶的比色法来检测L-Cys和Cu2+。结果表明，该检测平台简单、快速、灵敏、选择性好。L-Cys 和 Cu2+ 的检测限分别为 0.041 μM 和 0.056 μM，线性范围为 0.01 ~ 60.0 μM 和 0.05 ~ 80.0 μM。PtCo双金属基纳米酶在比色传感中的首次成功应用为纳米酶和比色分析开辟了新的方向，显示出巨大的应用潜力。