Quantification of trace polystyrene nanoplastics in aquatic environments using hybrid substrates of gold-loaded dendritic mesoporous silica and silver-decorated graphene nanosheets for surface-enhanced Raman scattering analysis

A homogeneous SERS platform was developed for detecting polystyrene nanoplastics (PS NPs) using an Au@DMSN/Ag@GNS substrate. This substrate combines electrostatically assembled dendritic mesoporous silica nanospheres (DMSN) functionalized with Au NPs and graphene nanosheets (GNS) decorated with Ag NPs. Systematic optimization revealed interfacial interaction mechanisms between the substrate and PS NPs, achieving enhanced detection performance. The platform demonstrated a linear response (R=0.996) for 200-500 nm PS NPs with a 3.70 × 10 enhancement factor and 0.1 μg/mL detection limit. The substrate's fingerprinting capability enabled differentiation of two-component NPs, while maintaining excellent stability and anti-interference across detection sites. Practical application in lake water samples showed 91.18 %-109.27 % recovery rates with 3.24 %-11.66 % RSDs. The system successfully detected low-concentration PS NPs with broad size distributions in diverse aqueous environments (lakes, oceans, and polluted ditch waters), effectively tackling challenges posed by moderate NP sizing heterogeneity under real-world conditions. This work advances hotspot engineering strategies for SERS substrates through rational 2D/3D structural design, offering a promising solution for environmental NP monitoring.