Carbon dots (CDs) with excellent optical properties are widely used in biomedicine, fluorescence sensing, and light‐emitting diodes (LEDs). However, it is still a challenge to prepare CDs that can stably emit red fluorescence in the water environment. In this study, polydopamine‐encapsulated luminescent carbon dots (CDs@PDA) with an encapsulating structure were synthesized at room temperature from p‐phenylenediamine‐derived red‐light CDs as the core and using mussel‐inspired chemical properties of polydopamine (PDA). In the binary system of water:ethanol = 1: 3 (volume ratio), the as‐prepared CDs@PDA had a dual emission of ultraviolet light (330 nm) and red light (640 nm) with the fluorescence quantum yields of 8.0 and 15.5%, respectively, at the same time under 285 nm light excitation. The as‐prepared CDs@PDA could be directly used for fluorescence selective sensing of 4‐nitrophenol (4‐NP) and Fe³⁺ through simultaneously quenching of ultraviolet and red fluorescence based on the internal filtration effect mechanism with detection limits of 3.44 and 3.75 μM, respectively. This research showed that PDA‐coated CDs can significantly improve the photoluminescence stability of CDs with new optical features. This means that the encapsulated structure of mussel chemistry is very helpful for expanding the application range of CDs in the water environment.

中文翻译：

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贻贝启发的聚多巴胺封装的碳点双发射，可检测4-硝基苯酚和Fe3 +

具有出色光学性能的碳点（CD）广泛用于生物医学，荧光传感和发光二极管（LED）。然而，制备可在水环境中稳定发射红色荧光的CD仍然是一个挑战。在这项研究中，在室温下由p合成了具有多聚结构的聚多巴胺封装的发光碳点（CDs @ PDA）。苯二胺衍生的红光CD为核心，并利用贻贝激发的聚多巴胺（PDA）的化学性质。在水：乙醇= 1：3（体积比）的二元系统中，制备的CDs @ PDA具有紫外光（330 nm）和红光（640 nm）的双重发射，荧光量子产率为8.0和同时在285 nm的光激发下分别达到15.5％。所制备的CDs @ PDA可直接用于4-硝基苯酚（4-NP）和Fe ^3+的荧光选择性传感通过基于内部过滤效应机理的紫外和红色荧光同时猝灭，检测极限分别为3.44和3.75μM。这项研究表明，涂有PDA的CD可以显着提高具有新光学功能的CD的光致发光稳定性。这意味着贻贝化学的封装结构对于扩大CD在水环境中的应用范围非常有帮助。