In this report, we successfully engineered a novel probe based on an acceptor–donor–acceptor (A–D–A) architecture featuring dicyanovinyl-substituted thieno[3,2-b]thiophene, termed DCVTT. The designed probe self-assembles into luminous nanoparticles (DCVTT NPs) upon introducing mixed aqueous solutions. These fluorescent nanostructures served as a ratiometric probe for detecting cyanide (CN⁻) ions in aqueous-based environments, owing to the robust Intramolecular Charge Transfer (ICT) characteristics of DCVTT. The A–D–A substituents in DCVTT significantly enhanced ICT behavior by promoting more efficient electron transfer between the donor and acceptor groups. This improved electron transfer process leads to heightened sensitivity in detection applications. In the case of cyanide (CN) sensing, this enhanced ICT behavior manifests as a strong colorimetric response, allowing for a visible color change before and after interaction with cyanide. Speculation regarding the interaction mechanism between DCVTT and CN⁻ is proposed based on the findings of various experimental analyses. The detection limit (LOD) for DCVTT in identifying CN⁻ is 0.83 nM, significantly lower than the CN⁻ concentration thresholds deemed safe by the World Health Organization (WHO) and the United States Environmental Protection Agency (EPA). Time-Dependent Density Functional Theory (TD-DFT) has been utilized to theoretically analyze the optical properties of DCVTT both before and after the introduction of the CN⁻ ions. A paper-based test strip was developed to demonstrate its practical application to enable efficient qualitative CN⁻ detection by visual inspection. Furthermore, this sensing platform demonstrates highly accurate quantitative detection of CN⁻ in apple seeds. No prior reports have utilized fluorescence techniques to estimate apple seeds’ CN levels.

中文翻译：

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基于 ICT 的荧光纳米颗粒用于苹果种子中的选择性氰离子检测和定量


在本报告中，我们成功设计了一种基于受体-供体-受体 （A-D-A） 结构的新型探针，其特点是二亚诺维尼取代的噻吩并[3,2-b]噻吩，称为 DCVTT。设计的探针在引入混合水溶液后自组装成发光纳米颗粒 （DCVTT NPs）。由于 DCVTT 强大的分子内电荷转移 （ICT） 特性，这些荧光纳米结构用作在水基环境中检测氰化物 （CN⁻） 离子的比率探针。DCVTT 中的 A-D-A 取代基通过促进供体和受体组之间更有效的电子转移，显着增强了 ICT 行为。这种改进的电子转移过程提高了检测应用的灵敏度。在氰化物 （CN） 传感的情况下，这种增强的 ICT 行为表现为强烈的比色响应，允许在与氰化物相互作用之前和之后出现可见的颜色变化。根据各种实验分析的结果，提出了关于 DCVTT 和 CN⁻ 之间相互作用机制的推测。DCVTT 鉴定 CN⁻ 的检测限 （LOD） 为 0.83 nM，明显低于世界卫生组织 （WHO） 和美国环境保护署 （EPA） 认为安全的 CN⁻ 浓度阈值。时间依赖性密度泛函理论 （TD-DFT） 已被用于理论分析引入 CN⁻ 离子之前和之后 DCVTT 的光学特性。 开发了一种纸质试纸来展示其实际应用，以便通过目视检查实现高效的定性 CN⁻ 检测。此外，该传感平台还展示了苹果种子中 CN⁻ 的高精度定量检测。之前没有报道使用荧光技术来估计苹果种子的 CN 水平。