Nanoplastics (NPs) are growing concerns for health and the environment, being widely distributed across marine, freshwater, air, and biological systems. Analyzing NPs in real environmental samples requires pretreatment, which has traditionally been complex and often leads to underestimation in actual samples, creating a gap between real-world conditions and research findings. In this study, we propose using anodic aluminum oxide (AAO) membrane as a direct Raman substrate for particles on a filter, achieving complete recovery during separation and concentration while simplifying the pretreatment stages. Moreover, our study introduces AAO itself, without any metal coating, as a normal Raman spectroscopy substrate with strong Raman signal enhancement for NPs and an ultra-flat surface for rapid analysis. By using AAO with nanometer-sized pores, we effectively detected standard polystyrene spherical particles on the AAO membrane down to 200 nm. Our investigation extended to irregular NPs containing PP, PE, PET, PS, PMMA, and PLA, confirming the reliability of this approach. Our results suggest that employing an AAO membrane with dual functionality as both a filter and a Raman substrate effectively serves as a cost-effective, rapid, simple, and accurate tool for NP analysis in complex environments.

中文翻译：

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无金属 AAO 膜可用作纳米塑料分析的过滤器和拉曼增强剂


纳米塑料 （NP） 越来越受到健康和环境的关注，广泛分布在海洋、淡水、空气和生物系统中。分析真实环境样品中的 NP 需要预处理，这在传统上很复杂，并且经常导致实际样品中的低估，从而在真实世界条件和研究结果之间产生差距。在本研究中，我们建议使用阳极氧化铝 （AAO） 膜作为过滤器上颗粒的直接拉曼衬底，在分离和浓缩过程中实现完全回收，同时简化预处理阶段。此外，我们的研究引入了 AAO 本身，没有任何金属涂层，作为普通的拉曼光谱基底，对 NP 具有很强的拉曼信号增强和超平坦的表面，可用于快速分析。通过使用具有纳米级孔隙的 AAO，我们有效地检测了 AAO 膜上低至 200 nm 的标准聚苯乙烯球形颗粒。我们的调查扩展到含有 PP、PE、PET、PS、PMMA 和 PLA 的不规则 NP，证实了这种方法的可靠性。我们的结果表明，将具有双重功能的 AAO 膜用作滤光片和拉曼基质，可以有效地作为复杂环境中 NP 分析的一种经济高效、快速、简单和准确的工具。