As a noninvasive and label-free optical technique, Raman spectroscopy offers significant advantages in studying the structure and properties of biomacromolecules, as well as real-time changes in cellular molecular structure. However, its practical applications are hindered by weak scattering responses, low signal intensity, and poor spectral uniformity, which affect the subsequent accuracy of spectral analysis. To address these issues, we report a novel surface-enhanced Raman scattering (SERS) substrate based on a pyramidal pitted silicon (PPSi) array structure adhered with Au-shell Ag-core nanospheres (Au@Ag NSs). By preparing a highly uniform PPSi array substrate with controllable size and arrangement, and constructing SERS-active Au@Ag NSs on this substrate, a three-dimensional (3D) composite SERS substrate is realized. The enhancement performance and spectral uniformity of 3D composite SERS substrate were examined using crystal violet (CV) and Rhodamine 6G (R6G) molecules, achieving a minimum detectable concentration of R6G at 10−9 M and the analytical enhancement factor (AEF) of 4.2 × 108. Moreover, SERS detection of biological samples with varying concentrations of Staphylococcus aureus demonstrated excellent biocompatibility of the SERS substrate and enabled quantitative analysis of bacterial concentration (R 2 = 99.7 %). Theoretical simulations using finite-difference time-domain (FDTD) analysis were conducted to examine the electromagnetic field distribution of the three-dimensional SERS composite substrate, confirming its local electric field enhancement effect. These experimental and theoretical results indicate that the Au@Ag NSs/PPSi substrate with a regulable pyramidal pitted array is a promising candidate for sensitive, label-free SERS detection in medical and biotechnological applications.

中文翻译：

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基于金字塔形点蚀硅阵列粘附Au@Ag纳米球的三维复合衬底，用于高性能表面增强拉曼散射


作为一种无创、无标记的光学技术，拉曼光谱在研究生物大分子的结构和性质以及细胞分子结构的实时变化方面具有显著优势。然而，其实际应用受到散射响应弱、信号强度低和光谱均匀性差的阻碍，影响了后续光谱分析的准确性。为了解决这些问题，我们报道了一种基于金字塔形点蚀硅 （PPSi） 阵列结构的新型表面增强拉曼散射 （SERS） 衬底，该结构粘附在 Au 壳层 Ag 核心纳米球 （Au@Ag NSs） 上。通过制备尺寸和排列可控的高度均匀的 PPSi 阵列衬底，并在该衬底上构建 SERS 活性Au@Ag NSs，实现了三维 （3D） 复合 SERS 衬底。使用结晶紫 （CV） 和罗丹明 6G （R6G） 分子检查 3D 复合 SERS 衬底的增强性能和光谱均匀性，在 10-9 M 处达到 R6G 的最低可检测浓度和 4.2 × 108 的分析增强因子 （AEF）。此外，对具有不同浓度金黄色葡萄球菌的生物样品进行 SERS 检测，证明 SERS 底物具有出色的生物相容性，并能够定量分析细菌浓度 （R2 = 99.7 %）。使用有限差分时域 （FDTD） 分析进行了理论仿真，以检验三维 SERS 复合基板的电磁场分布，证实了其局部电场增强效果。 这些实验和理论结果表明，具有可调节金字塔点蚀阵列的 Au@Ag NSs/PPSi 底物是医学和生物技术应用中灵敏、无标记 SERS 检测的有前途的候选者。