To achieve high sensitivity and uniformity simultaneously in a surface-enhanced Raman scattering (SERS) substrate, this paper presents the preparation of a flexible and transparent three-dimensional (3D) ordered hemispherical array polydimethylsiloxane (PDMS) film. This is achieved by self-assembling a single-layer polystyrene (PS) microsphere array on a silicon substrate. The liquid-liquid interface method is then used to transfer Ag nanoparticles onto the PDMS film, which includes open nanocavity arrays created by etching the PS microsphere array. An open nanocavity assistant soft SERS sample, “Ag@PDMS,” is then prepared. For electromagnetic simulation of our sample, we utilized Comsol software. It has been experimentally confirmed that the Ag@PDMS substrate with silver particles of 50 nm in size is capable of achieving the largest localized electromagnetic hot spots in space. The optimal sample, Ag@PDMS, exhibits ultra-high sensitivity towards Rhodamine 6 G (R6G) probe molecules, with a limit of detection (LOD) of 10−15 mol/L, and an enhancement factor (EF) of ∼1012. Additionally, the substrate exhibits a highly uniform signal intensity for probe molecules, with a relative standard deviation (RSD) of approximately 6.86%. Moreover, it is capable of detecting multiple molecules and can perform real detection on non-flat surfaces.
Surface-enhanced Raman scattering (SERS) has gained widespread attention as an effective method for trace molecular detection. Herein, a bowl-structured Ag NPs@Ag-PDMS substrate was developed via a multi-step assembly strategy, where silver nanoparticles (Ag NPs) were partially embedded into the bowl-structured surface of a polydimethylsiloxane (PDMS) matrix while additional Ag NPs were incorporated into the interior. This synergistic architecture significantly amplified the local electromagnetic field, as confirmed by experiments and finite element simulations. Using rhodamine 6G (R6G) as a probe and a fiber Raman spectrometer, the optimized substrate enabled detection at 5 nM with an enhancement factor of 1.22 × 10 6 . The substrate also exhibited good signal uniformity with a relative standard deviation of 6.99 % and maintained performance after five rinsing–reuse cycles. Furthermore, it successfully detected thiram residues on apple peels, showing a linear response down to 3 ng/cm 2 . These findings highlight the high sensitivity, reproducibility, and reusability of the substrate, indicating strong potential for real-world SERS applications in food inspection, environmental analysis, and public health screening.
Heng Guo,Hongji Li,Mengyang Xu,Juan Zhou,Dan Zhang,Dandan Wang,Wei Sun
In this study, a core–shell structured bimetallic nano-cube, Au@Ag NCs, was prepared by seed-mediated growth procedure. The array structure of Au@Ag NCs was achieved at the interface through the autonomous assembly technique at the three-phase boundary. Employing polydimethylsiloxane (PDMS) as a flexible carrier, the array structure was effortlessly transferred to the PDMS membrane, bypassing the need for rigid substrates through a simple “pasting” method. This yielded a highly flexible and transparent SERS substrate with an array structure (Au@Ag NCs/PDMS membrane, AAP). In order to promote the selective detection property to the practical samples, molecularly imprinted polymers (MIPs) were coated on the surface of membrane to prepare the imprinted membrane (Au@Ag NCs/PDMS-MIMs, AAP-MIMs). It was demonstrated from the results that the AAP-MIMs exhibited high SERS sensitivity, stability, and uniformity. Furthermore, the flexible substrate possessed commendable mechanical strength, and facilitated the detection of analytes on irregular surfaces. In summary, this substrate held promising potential for practical on-site detection and analysis of specific target substances.
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