State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Biology, Hunan University , Changsha, 410082, China.
Anal Chem. 2015 Mar 3;87(5):2734-40. doi: 10.1021/ac504000p. Epub 2015 Feb 9.
Although surface-enhanced Raman spectroscopy (SERS) has been featured by high sensitivity, additional signal enhancement is still necessary for trace amount of biomolecules detection. In this paper, a SERS amplified approach, featuring "ions-mediated cascade amplification (IMCA)", was proposed by utilizing the dissolved silver ions (Ag(+)) from silver nanoparticles (AgNPs). We found that using Ag(+) as linkage agent can effectively control the gaps between neighboring 4-aminobenzenethiol (4-ABT) encoded gold nanoparticles (AuNPs@4-ABT) to form "hot spots" and thus produce SERS signal output, in which the SERS intensity was proportional to the concentration of Ag(+). Inspired by this finding, the IMCA was utilized for ultrasensitive detection of single nucleotide polymorphism in human mitochondrial DNA (16189T → C). Combining with the DNA ligase reaction, each target DNA binding event could successfully cause one AgNP introduction. By detecting the dissolved Ag(+) from AgNPs using IMCA, low to 3.0 × 10(-5) fm/μL targeted DNA can be detected, which corresponds to extractions from 200 nL cell suspension containing carcinoma pancreatic β-cell lines from diabetes patients. This IMCA approach is expected to be a universal strategy for ultrasensitive detection of analytes and supply valuable information for biomedical research and clinical early diagnosis.
尽管表面增强拉曼光谱（SERS）具有高灵敏度的特点，但对于痕量生物分子的检测仍需要额外的信号增强。在本文中，我们提出了一种 SERS 放大方法，即“离子介导级联放大（IMCA）”，利用纳米银颗粒（AgNPs）中的溶解银离子（Ag(+))。我们发现，使用 Ag(+)作为连接剂可以有效地控制相邻 4-巯基苯硼酸（4-ABT）编码金纳米颗粒（AuNPs@4-ABT）之间的间隙，从而形成“热点”，从而产生拉曼信号输出，其中拉曼信号强度与 Ag(+)的浓度成正比。受此发现启发，我们利用 IMCA 对人线粒体 DNA（16189T → C）中的单核苷酸多态性进行了超灵敏检测。结合 DNA 连接酶反应，每个靶 DNA 结合事件都可以成功地引入一个 AgNP。通过 IMCA 检测 AgNPs 中的溶解 Ag(+)，可以检测到低至 3.0×10(-5)fm/μL 的靶向 DNA，相当于从糖尿病患者的胰腺癌细胞系中提取的 200nL 细胞悬浮液。这种 IMCA 方法有望成为超灵敏分析物检测的通用策略，并为生物医学研究和临床早期诊断提供有价值的信息。
