The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China.
ACS Sens. 2024 Aug 23;9(8):4295-4304. doi: 10.1021/acssensors.4c01539. Epub 2024 Aug 14.
Plasmonic Au-Ag nanostars are excellent surface-enhanced Raman scattering (SERS) probes due to bimetallic coupling and the tip effect. However, the existing preparation methods of AuAg nanostars cannot achieve controlled growth of the Ag layer on the branches of nanostars and so cannot display their SERS to the maximum extent, thus limiting its sensitivity in biosensing. Herein, a novel strategy "PEI (polyethylenimine)-guided Ag deposition method" is proposed for synthesizing AuAg core-shell nanostars (AuAg@Ag NS) with a tunable distribution of the Ag layer from the core to the tip, which offers an avenue for investigating the correlation between SERS efficiency and the extent of spread of the Ag layer. It is found that AuAg@Ag NS with a Ag layer coated the whole branch has the strongest SERS performance because the coupling between the tips and Ag layer is maximized. Meanwhile, as a completely closed core-shell structure, AuAg@Ag NS can confine and anchor 4-ATP inside the Ag layer to avoid an unstable SERS signal. By connecting the aptamer, a reliable internal standard nanoprobe with a SERS enhancement factor (EF) up to 1.86 × 10 is prepared. Okada acid is detected through competitive adsorption of this SERS probes, and the detection limit is 36.6 pM. The results gain fundamental insights into tailoring the nanoparticle morphologies and preparation of internal standard nanoprobes and also provide a promising avenue for marine toxin detection in food safety.
等离子体 Au-Ag 纳米星由于双金属耦合和尖端效应，是出色的表面增强拉曼散射（SERS）探针。然而，现有的 AuAg 纳米星制备方法不能控制 Ag 层在纳米星支上的生长，因此不能最大限度地发挥其 SERS 性能，从而限制了其在生物传感中的灵敏度。在此，提出了一种新颖的策略，即“PEI（聚乙烯亚胺）引导的 Ag 沉积法”，用于合成具有从核到尖端可调 Ag 层分布的 AuAg 核壳纳米星（AuAg@Ag NS），为研究 SERS 效率与 Ag 层扩展程度之间的相关性提供了途径。研究发现，Ag 层覆盖整个支的 AuAg@Ag NS 具有最强的 SERS 性能，因为尖端和 Ag 层之间的耦合最大化。同时，作为一种完全封闭的核壳结构，AuAg@Ag NS 可以将 4-ATP 限制并固定在 Ag 层内，以避免不稳定的 SERS 信号。通过连接适体，制备了具有高达 1.86×10 的 SERS 增强因子（EF）的可靠的内部标准纳米探针。通过竞争吸附这种 SERS 探针检测到冈田酸，检测限为 36.6 pM。结果深入了解了纳米颗粒形态的调整和内部标准纳米探针的制备，为食品安全中海洋毒素的检测提供了有前途的途径。
