In the present work, we report a novel colorimetric sensor array for rapid identification of heavy metal ions. The sensing mechanism is based on the competition between thiols and urease for binding with the metal ions. Due to the different metal ion-binding abilities between the thiols and urea, different percentages of urease are free of metal ions and become catalytically active in the presence of varied metal ions. The metal ion-free urease catalyzes the decomposition of urea releasing ammonia and changing the pH of the analyte solution. Bromothymol blue, the pH indicator, changes its color in response to the metal-caused pH change. Three different thiols (l-glutathione reduced, l-cysteine, and 2-mercaptoethanol) were used in our sensor array, leading to a unique colormetric repsonse pattern for each metal. Linear discriminant analysis (LDA) was employed to analyze the patterns and generate a clustering map for identifying 11 species of metal ions (Ni²⁺, Mn²⁺, Zn²⁺, Ag⁺, Cd²⁺, Fe³⁺, Hg²⁺, Cu²⁺, Sn⁴⁺, Co²⁺, and Pb²⁺) at 10 nM level in real samples. The method realizes the simple, fast (within 30 s), sensitive, and visual discrimination of metal ions, showing the potential applications in environmental monitoring.

中文翻译：

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基于三种硫醇为受体的比色传感器阵列用于水溶液中重金属离子的鉴别

在目前的工作中，我们报告了一种新型的比色传感器阵列，用于快速鉴定重金属离子。感测机制基于硫醇和脲酶之间与金属离子结合的竞争。由于硫醇与尿素之间的金属离子结合能力不同，因此不同百分比的脲酶不含金属离子，并且在存在各种金属离子的情况下具有催化活性。无金属离子的尿素酶催化尿素的分解，释放出氨并改变分析物溶液的pH。pH指示剂溴百里酚蓝响应于金属引起的pH值变化而改变其颜色。三种不同的硫醇（l-谷胱甘肽还原，l-半胱氨酸和2-巯基乙醇）用于我们的传感器阵列，从而为每种金属提供了独特的色度表观模式。使用线性判别分析（LDA）分析模式并生成聚类图，以识别11种金属离子（Ni 2 ⁺，Mn 2 ⁺，Zn 2 ⁺，Ag ⁺，Cd 2 ⁺，Fe ³⁺，Hg ²，真实样品中的10 nM浓度的⁺，Cu 2 ⁺，Sn ⁴⁺，Co ²⁺和Pb ²⁺）。该方法实现了金属离子的简单，快速（在30 s之内），灵敏和视觉识别，显示了在环境监测中的潜在应用。