基于去合金化技术的高活性多针孔SERS探针的可控制备及其在细胞分析中的应用

Studies on Surface-enhanced Raman scattering (SERS) have shown that hot spots provide huge enhancement to Raman signals, taking advantage of which single molecule detection could be reached, and thus construction of SERS probes containing hot spots has been one of the most important parts of research on Raman spectroscopy. Pinholes with several nanometer size formed through replacement reaction between Ag and Chloroauric acid were demonstrated high efficient hot spots. In view of the fact that only one hole was generated in a single nanoparticle during the alloying process of pure Ag nanoparticles with Chloroauric acid, this project intends to synthesize porous nanoparticles by dealloying of Ag/Au alloy nanoparticles and high efficient SERS probes with optimum ratio of pore size and ligament size in the form of one nanoparticle contains several pinholes were obtained by precisely midifying the pore structure. Based on the novel multiply pinhole structure, such kind of Raman probe would exhibit 1-2 orders of magnitude lager enhancement than single pinhole probes, and consequently reduce the usage amount as well as the power of excitation light, making it especially suitable for cell analysis. Additionally, such probes were expected to improve the weak signal and poor stability of current Raman probes applied for cell analysis, obtaining the real Raman signal of intracellular biomolecules sensitively and stably and providing technical and theoretical basis for the application of SERS spectroscopy in biomedical field.

表面增强拉曼散射(SERS)研究表明热点结构对拉曼信号有巨大的增强作用，可以实现单分子检测，包含不同形式热点的SERS探针的建构已成为拉曼光谱技术研究的重要内容。其中通过银与氯金酸的置换反应形成的几个纳米的针孔结构被证实是高效的SERS热点。针对实验上利用纯银颗粒在与氯金酸反应形成合金的过程中只会形成一个针孔热点的现状，本项目采用银/金合金纳米颗粒去合金化的方法制备多孔纳米粒子，通过对多孔微观结构的精细修饰获得具有最佳孔径与连接体尺寸比的单颗粒多针孔高效SERS探针。由于该探针具有多个热点，相比于单针孔探针可获得1-2个数量级的增强，因此可以减小使用量和激发光功率，有利于在细胞分析中的应用，并有望改善目前用于细胞分析的拉曼探针信号弱、稳定性差的状况，灵敏、稳定地获得细胞内生物分子的真实信息，为SERS光谱在生物医学领域的应用提供技术基础和理论依据。

表面增强拉曼散射（SERS）效应因具有无损、高灵敏等优点在痕量检测、生物医学等领域受到越来越多的关注。构建高密度热点结构是获得高灵敏SERS基底的重要途径，因此探索具有纳米孔洞、纳米缝隙等热点结构的SERS探针的制备对拉曼光谱技术的发展具有重要意义。围绕具有高密度热点结构、高活性SERS探针的制备及用其实现细胞样品拉曼光谱检测的研究目标，本项目通过制备分形结构、去合金化、生成褶皱裂缝、不等价置换等多种手段构建高密度热点结构，并将其相结合获得具有高增强性能的SERS基底。实验结果显示，分形结构SERS基底的增强因子达到了6.7×108。通过磁控溅射对去合金化方法构建的高密度孔洞结构尺寸进行修饰，与修饰前相比，SERS基底的增强效应提高了一个数量级。在去合金化制备的多孔结构中生成褶皱裂缝，增强性能提高了6倍；多孔褶皱结构进一步经Ag生长修饰后，增强性能又提高了50倍。通过不等价置换在Au@Ag纳米颗粒上构建孔洞结构，并结合等价置换对孔洞尺寸进行调控，将此SERS探针用于体外活体大肠杆菌拉曼信号的检测，得到了明确的大肠杆菌拉曼信号。以上结果表明，本项目通过多种手段探索制备的具有高增强性能的SERS探针在痕量检测及生物样品拉曼光谱的探测等方面具有较好的应用前景。