In this study, we developed a dual-channel fluorescent dye (()--(4-(diphenylamino)benzylidene)pyrazine-2-carbohydrazide) DPC for visual detection of 8 types of microplastics (MPs; HDPE, MDPE, LDPE, PET, PU, PVC, PS, and PP) and selective PU. The intramolecular charge transfer (ICT) and aggregation-induced emission (AIE) properties of DPC were demonstrated by the spectroscopic analysis, DFT calculations, and Tyndall effect. MPs and nonplastics (cellulose, chitin, sand, shell, and wood) were stained with DPC in water and their respective fluorescence signals in the blue and green channels were analyzed. The staining procedure using DPC was optimized with the concentration of DPC and staining time as parameters. DPC was able to effectively stain 8 types of MPs and only PU in blue and green fluorescence signals, respectively. Furthermore, false positive detections of DPC were minimized through additional ethanol treatment after staining. Moreover, the effects of temperature, pH, and salinity on the staining ability of DPC were investigated. Surprisingly, DPC was able to selectively detect PU through the green fluorescence signal even in a single environment where various MPs existed. Most importantly, DPC is the first fluorescent dye capable of selectively monitoring PU in the green channel as well as staining 8 types of MPs in the blue channel. DPC showed promising potential to be used for MP monitoring on real environmental samples.

中文翻译：

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双通道荧光染料：微塑料和选择性聚氨酯的荧光颜色依赖性视觉检测

在这项研究中，我们开发了一种双通道荧光染料 (()--(4-(二苯氨基)亚苄基)吡嗪-2-碳酰肼) DPC，用于视觉检测 8 种微塑料 (MP；HDPE、MDPE、LDPE、PET) 、PU、PVC、PS 和 PP）和选择性 PU。通过光谱分析、DFT 计算和廷德尔效应证明了 DPC 的分子内电荷转移 (ICT) 和聚集诱导发射 (AIE) 特性。 MP 和非塑料（纤维素、甲壳质、沙子、贝壳和木材）在水中用 DPC 染色，并分析它们各自在蓝色和绿色通道中的荧光信号。以 DPC 浓度和染色时间为参数优化 DPC 染色程序。 DPC 能够分别有效地对蓝色和绿色荧光信号中的 8 种 MP 和 PU 进行染色。此外，通过染色后额外的乙醇处理，可以最大限度地减少 DPC 的假阳性检测。此外，还研究了温度、pH和盐度对DPC染色能力的影响。令人惊讶的是，即使在存在各种 MP 的单一环境中，DPC 也能够通过绿色荧光信号选择性地检测 PU。最重要的是，DPC 是第一种能够选择性监测绿色通道中的 PU 以及在蓝色通道中对 8 种 MP 进行染色的荧光染料。 DPC 显示出用于真实环境样品 MP 监测的巨大潜力。