In this study, three types of Fe(III) bipyridyl or phenanthroline (Fe(III)‐L₃) complex could directly catalyze 3,3′,5,5′‐tetramethylbenzidine (TMB) to induce blue chromogenic changes without H₂O₂. Fe(III)‐L₃ complex could induce a colour change in TMB directly after a short incubation time. Due to the high oxidase‐like activity of the Fe(III)‐L₃ complexes, superoxide anion radicals (O₂^•–) were formed in solution. Intermediates radical involving oxo‐iron species were then produced that oxidized TMB to its oxidation products (oxTMB), which had an absorbance maximum at 652 nm. Glutathione (GSH) could inhibit the oxidation reaction of the Fe(III)‐L₃ complex–TMB system, a rapidly colorimetric method was established for the specific detection of GSH that had a detection limit of 0.1 μM. Furthermore, Fe(III)‐L₃ complexes could catalyze TMB to oxTMB directly without H₂O₂. This fast and simple colorimetric method may open a new avenue for application in the point‐of‐care diagnosis field using the TMB chromogenic system.

中文翻译：

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Fe（III）联吡啶或菲咯啉配合物具有类似氧化酶的活性，用于谷胱甘肽的比色检测。

在这项研究中，三种类型的Fe（III）联吡啶或菲咯啉（Fe（III）-L ₃）络合物可以直接催化3,3'，5,5'-四甲基联苯胺（TMB）诱导蓝色发色变化，而无需H ₂ O ₂。Fe（III）-L ₃复合物可在短时间孵育后直接诱导TMB发生颜色变化。由于Fe（III）-L ₃络合物具有高氧化酶样活性，因此在溶液中形成了超氧阴离子自由基（O ₂ ^•–）。然后产生了涉及含氧铁物种的中间体自由基，该自由基将TMB氧化成其氧化产物（oxTMB），在652 nm处具有最大吸收。谷胱甘肽（GSH）可以抑制Fe（III）‐L ₃的氧化反应对于复杂的TMB系统，已建立了一种快速比色法，用于GSH的特异性检测，其检测限为0.1μM。此外，Fe（III）-L ₃络合物可以在没有H ₂ O _2的情况下直接将TMB催化为oxTMB 。这种快速，简单的比色方法可能会为使用TMB生色系统的即时诊断领域开辟新的途径。