Size-matching effects in quantitative detection of PS nanoplastics using controllable and reusable Ag nanoarrays SERS substrates

This study proposes a strategy for the highly sensitive detection of polystyrene nanoplastics (PS NPs) with varying particle sizes. Ag nanoarrays (AgNAs) with different inter-column spacings and heights are fabricated via thermal deposition of Ag in anodized aluminum oxide (AAO) templates. The size-matching effects between PS NPs and the parameters of the AgNAs (inter-column spacing and height) are investigated. Utilizing this size-matching effect, the AgNAs substrate enables sensitive detection of PS NPs with particle sizes of 130 nm, 180 nm, and 230 nm, with limits of detection (LODs) of 10 μg/mL. In real water samples (river water, rainwater, and tap water), the AgNAs substrate also demonstrates good performance, achieving a LOD of 10 μg/mL for detecting 130 nm PS NPs. Additionally, toluene is used to remove PS NPs from the AgNAs surface, allowing the substrate to be reused across multiple cycles. After at least 30 detection cycles, the surface-enhanced Raman scattering (SERS) performance of the AgNAs shows no significant decline, with a relative standard deviation (RSD) of 6.8 %. The AgNAs exhibit excellent stability and reusability in detecting PS NPs, indicating strong potential for practical applications.