Department of Chemistry, Faculty of Arts and Sciences, Gaziantep University, 27310, Gaziantep, Turkey.
Nanoscale. 2023 Aug 25;15(33):13770-13783. doi: 10.1039/d3nr02602g.
Surface-enhanced Raman scattering (SERS) is an emerging spectroscopy technique for detecting and characterizing chemical or biological structures in the vicinity of plasmonic nanostructures. Colloidal, solid, and flexible nanostructures are widely used in SERS experiments to enhance the Raman intensity. The nanostructure used in SERS is one of the main influencing parameters and a growing research area. Fabrication of simple and cheap SERS substrates with a high enhancement factor is desired. In this study, we fabricated a reproducible, cheap, and flexible SERS active strip by coating natural diatomite (biosilica) with silver nanoparticles (AgNPs) using the layer-by-layer assembly method and the fabricated strip is used for the label-free identification of circulating cancer protein biomarkers. SERS active strips were fabricated having different numbers of AgNP layers on natural diatomite and comprehensive characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV/vis absorption spectrophotometry were used. SERS activities of the strips depending on the number of layers were evaluated using 4-aminothiophenol (4-ATP) and rhodamine 6G (Rh6G) molecules. We found that the SERS intensity is strongly dependent on the number of AgNP layers, with the maximum SERS intensity obtained from the strip with 5 layers of AgNPs, having a 2.0 × 10 enhancement factor. The strip with the highest SERS activity was used for the label-free identification of circulating cancer protein biomarkers (HER2, CA15-3, PSA, MUC4, and CA27-29). The results demonstrate that the fabricated strip can help in the effective label-free identification of circulating protein biomarkers and open new directions for SERS-based label-free biosensing applications.
表面增强拉曼散射（SERS）是一种新兴的光谱技术，用于检测和表征等离子体纳米结构附近的化学或生物结构。胶体、固态和柔性纳米结构广泛应用于 SERS 实验中以增强拉曼强度。在 SERS 中使用的纳米结构是主要影响参数之一，也是一个不断发展的研究领域。人们希望制备具有高增强因子的简单、廉价的 SERS 基底。在这项研究中，我们通过使用层层组装法用银纳米粒子（AgNPs）涂覆天然硅藻土（生物硅）来制备具有重现性、廉价和柔性的 SERS 活性条带，并将该条带用于无标记识别循环肿瘤蛋白生物标志物。在天然硅藻土上制备了具有不同 AgNP 层数的 SERS 活性条带，并使用了 X 射线衍射（XRD）、扫描电子显微镜（SEM）和紫外/可见吸收分光光度法等综合表征技术。使用 4-巯基苯胺（4-ATP）和罗丹明 6G（Rh6G）分子评估了条带的 SERS 活性与层数的关系。我们发现 SERS 强度强烈依赖于 AgNP 层数，其中具有 5 层 AgNPs 的条带获得了最大的 SERS 强度，增强因子为 2.0×10。具有最高 SERS 活性的条带用于无标记识别循环肿瘤蛋白生物标志物（HER2、CA15-3、PSA、MUC4 和 CA27-29）。结果表明，所制备的条带有助于有效无标记识别循环蛋白生物标志物，并为基于 SERS 的无标记生物传感应用开辟了新的方向。
