Quantification and identification of microplastics (MPs) (plastics < 5 mm) remain challenging due to the current laborious, inconsistent, and time-intensive measurement techniques. A promising time- and cost-effective alternative is staining with the fluorescent dye Nile red (NR). This review covers the wide range of NR staining methods, illumination conditions, and instrumentation for fluorescence-based detection and classification that have been developed thus far, highlighting the potential of NR fluorescence imaging to distinguish plastics. Despite notable advancements in NR staining techniques and conditions that have strengthened detection capabilities, there remains a need for further development and standardization of NR staining protocols, fluorescence imaging methods, and illumination instruments. We conduct a thorough assessment of both the advantages and limitations associated with diverse fluorescence imaging instruments, image segmentation, and classification techniques employed for detecting NR fluorescence and identifying polymer species. We also highlight critical considerations that should guide future research efforts to establish NR staining as a comprehensive, standalone method for environmental monitoring. They include investigating fluorescence behavior, especially intensity and Stokes shift, to understand the impact of solvent functional groups, plastic materials, additives and color pigments, weathering and application methods on NR sorption and fluorescence. Consideration of these factors will improve the ability to accurately identify polymer types based on their fluorescent behaviors, promoting widespread adoption of fluorescence imaging as a standalone method and enhancing cross-compatibility between NR studies.

由于目前的测量技术费力、不一致且耗时，微塑料 (MP)（小于 5 毫米的塑料）的量化和识别仍然具有挑战性。一种有前途且经济高效的替代方案是使用荧光染料尼罗红 (NR) 进行染色。本综述涵盖了迄今为止已开发的各种 NR 染色方法、照明条件以及用于基于荧光的检测和分类的仪器，强调了 NR 荧光成像在区分塑料方面的潜力。尽管 NR 染色技术和条件取得了显着进步，增强了检测能力，但仍需要进一步开发和标准化 NR 染色方案、荧光成像方法和照明仪器。我们对用于检测 NR 荧光和识别聚合物种类的各种荧光成像仪器、图像分割和分类技术的优点和局限性进行了全面评估。我们还强调了应指导未来研究工作的关键考虑因素，以将 NR 染色建立为一种全面、独立的环境监测方法。其中包括研究荧光行为，特别是强度和斯托克斯位移，以了解溶剂官能团、塑料材料、添加剂和彩色颜料、耐候性和应用方法对 NR 吸附和荧光的影响。考虑这些因素将提高根据荧光行为准确识别聚合物类型的能力，促进荧光成像作为独立方法的广泛采用，并增强 NR 研究之间的交叉兼容性。