The first dual-modality highly intensive fluorescent and colorimetric nanoprobe for Fe3+ ions and histidine is reported. The carbon dots doped by nitrogen and sulfur (N,S-CDs) prepared by the one-pot hydrothermal method have an excitation/emission wavelength of 320/420 nm with 56% quantum yield. N,S-CDs exhibit strong visible fluorescence with high stability at pH ~ 7.0. The fluorescence intensity of the N,S-CDs is quenched in the presence of Fe3+ ions which are recovered upon the addition of histidine. The addition of Fe3+ ions also induces a color change from yellow to red. Using colorimetric determination, Fe3+ and histidine exhibited linearity in the range 75–675 and 100–375 μmol L−1, respectively, while with fluorometric determinations the dynamic range was 0.1–275 and 0.1–3 μmol L−1 for Fe3+ and histidine, respectively. The limits of detection were 19 nmol L−1 and 0.03 μmol L−1 using fluorometry and 20 μmol L−1 and 24.2 μmol L−1 using colorimetry, for Fe3+ and histidine respectively. The relative standard deviations (n = 5) for Fe3+ (10 μmol L−1) and histidine (1 μmol L−1) using fluorometry were 4.6 and 7.3% and using colorimetry at 100 μmol L−1 of Fe3+ and 150 μmol L−1 of histidine were 3.2 and 5.6%, respectively. The developed fluorometric method was applied for the determination of Fe3+ and histidine in various foods and biological fluid samples as well as intracellular imaging of iron. The accuracy of the method for iron determination was confirmed by the analysis of certified reference materials (wheat flour, tomato leaves, and whole milk powder) and quality control materials (whole milk powder, serum, and urine), whereas for histidine, the accuracy was determined by recovery experiment and independent analysis. Good recovery values in ranges of 92–96% and 94–98% were achieved for Fe3+ and histidine, respectively. Graphical abstract Graphical abstract

中文翻译：

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氮和硫掺杂的碳点用于活细胞中 Fe3+ 和组氨酸的双模式比色和荧光测定以及 Fe3+ 的细胞内成像

报道了第一个针对 Fe3+ 离子和组氨酸的双模态高强度荧光和比色纳米探针。一锅水热法制备的氮硫掺杂碳点(N,S-CDs)激发/发射波长为320/420 nm,量子产率为56%。N,S-CDs 在 pH ~ 7.0 下表现出强烈的可见荧光和高稳定性。N,S-CDs 的荧光强度在 Fe3+ 离子的存在下被淬灭，Fe3+ 离子在添加组氨酸后恢复。Fe3+ 离子的加入也会导致颜色从黄色变为红色。使用比色法测定，Fe3+ 和组氨酸分别在 75-675 和 100-375 μmol L-1 范围内表现出线性，而使用荧光法测定，Fe3+ 和组氨酸的动态范围为 0.1-275 和 0.1-3 μmol L-1，分别。Fe3+ 和组氨酸的检测限分别为 19 nmol L-1 和 0.03 μmol L-1（使用荧光法）和 20 μmol L-1 和 24.2 μmol L-1（使用比色法）。使用荧光法测定 Fe3+ (10 μmol L-1) 和组氨酸 (1 μmol L-1) 的相对标准偏差 (n = 5) 分别为 4.6% 和 7.3%，并在 100 μmol L-1 Fe3+ 和 150 μmol L− 处使用比色法1 的组氨酸分别为 3.2% 和 5.6%。开发的荧光法用于测定各种食品和生物体液样品中的 Fe3+ 和组氨酸，以及铁的细胞内成像。通过对有证标准物质（小麦粉、番茄叶和全脂奶粉）和质量控制物质（全脂奶粉、血清和尿液）的分析，证实了铁测定方法的准确性，而对于组氨酸，准确度由回收率实验和独立分析确定。Fe3+ 和组氨酸分别达到了 92-96% 和 94-98% 的良好回收率。图形摘要图形摘要