Herein, novel intrinsic dual-emitting carbon dots (CDs) are prepared through a one-step hydrothermal treatment of glucose and 3-nitroaniline in sulfuric acid solution and utilized for ratiometric determination of Cu2+ and aspartic acid (Asp). The CDs exhibited an interesting pH-switchable emission behavior displaying an intrinsic dual-emitting peak with emission maxima at 400 and 610 nm at pH 4.0-5.0. The presence of Cu2+ intensively quenched the first emission peak at 400 nm, but it had a negligible effect on the second emission peak. The ratiometric signal displayed a high selectively for Cu2+ over other metal ions and provided a linear response over the concentration range of 0.01-1.00 μM with a detection limit of 7.0 nM. Moreover, at pH 4.0, Asp was able to restore the quenched fluorescence of the CDs-Cu2+ system with a much more successful performance than other amino acids. This on-off-on fluorescence behavior provided a selective ratiometric fluorescence method for the determination of Asp in the concentration range of 0.2-15 μM. The acceptable detection results for Cu2+ in a river water sample (compared to Inductively Coupled Plasma (ICP) method) and for Asp in human serum samples confirmed the potential application of this ratiometric nanoprobe for sensing in real samples.

中文翻译：

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用于有效比例检测 Cu2+ 和天冬氨酸的本征双发射碳点

在此，通过葡萄糖和 3-硝基苯胺在硫酸溶液中的一步水热处理制备了新型本征双发射碳点 (CD)，并将其用于 Cu2+ 和天冬氨酸 (Asp) 的比例测定。CD 表现出有趣的 pH 可切换发射行为，显示出固有的双发射峰，发射最大值在 400 和 610 nm，pH 值为 4.0-5.0。Cu2+ 的存在强烈淬灭了 400 nm 处的第一个发射峰，但它对第二个发射峰的影响可以忽略不计。与其他金属离子相比，比例信号显示出对 Cu2+ 的高选择性，并在 0.01-1.00 μM 的浓度范围内提供线性响应，检测限为 7.0 nM。此外，在 pH 4.0 时，Asp 能够以比其他氨基酸更成功的性能恢复 CDs-Cu2+ 系统的淬灭荧光。这种开关荧光行为为测定 0.2-15 μM 浓度范围内的 Asp 提供了一种选择性的比率荧光方法。河水样品中 Cu2+ 的可接受检测结果（与电感耦合等离子体 (ICP) 方法相比）和人血清样品中的 Asp 证实了这种比率纳米探针在实际样品中传感的潜在应用。