Cysteine (Cys) is a bithiol that plays a vital role in many physiological processes. However, it is difficult to discriminate Cys from homocysteine (Hcy) and glutathione (GSH), due to their similar chemical structures and reactivity. Herein, we have developed a polymeric nanoprobe, nanoHFA, for ratiometric, highly selective, and sensitive detection of Cys based on 7-hydroxycoumarin-3-carboxylic acid (HC) and fluorescein isothiocyanate (FITC)-acrylate (FITC-A) group-functionalized lipopolymer DSPE-PEG. The probe nanoHFA showed a strong fluorescence emission peak centered at 450 nm attributed to HC and a weak fluorescence emission peak centered at 520 nm due to the photoinduced electron transfer (PET) process of FITC induced by acrylate group. In the presence of Cys, the fluorescence signal at 520 nm could be lit up and the ratio of F_520nm/F_450nm showed a good linear relationship in the range of 5–60 μM with a low detection limit of 0.37 μM. The probe also displayed excellent water solubility and high selectivity to Cys over other biothiols such as Hcy and GSH. Moreover, we further used probe nanoHFA to detect Cu²⁺ ions in the range of 100–550 nM with a detection limit of 77 nM. The nanoprobe was successfully applied for the quantitative detection of Cys in fetal bovine serum, and fluorescent strips were developed for facile and visual detection of Cys and Cu²⁺ ions.

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半胱氨酸（Cys）是一种在许多生理过程中都起着至关重要作用的Bithiol。然而，由于半胱氨酸（Hcy）和谷胱甘肽（GSH）的化学结构和反应性相似，因此很难将其与高半胱氨酸（Hcy）和谷胱甘肽（GSH）区分开。本文中，我们开发了一种聚合物纳米探针nanoHFA，用于基于7-羟基香豆素-3-羧酸（HC）和异硫氰酸荧光素（FITC）-丙烯酸酯（FITC-A）组的比例，高选择性和灵敏的Cys检测。功能化的脂聚合物DSPE-PEG。由于丙烯酸酯基团诱导的FITC的光诱导电子转移（PET）过程，探针nanoHFA显示出强集中在450nm处归因于HC的强荧光发射峰和弱集中在520nm处的弱荧光发射峰。在Cys的存在下，520 nm处的荧光信号会被照亮，且F _520nm / F _450nm在5–60μM范围内显示出良好的线性关系，而检测限为0.37μM。与其他生物硫醇（如Hcy和GSH）相比，该探针还显示出优异的水溶性和对Cys的高选择性。此外，我们还使用探针nanoHFA来检测100–550 nM范围内的Cu ²⁺离子，检测限为77 nM。纳米探针已成功用于定量检测胎牛血清中半胱氨酸，并开发了荧光条，可方便，直观地检测半胱氨酸和铜²⁺离子。

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