Department of Genetics and Bioengineering, Yeditepe University, Kayişdaği/Kadiköy, Istanbul, 34755, Turkey.
Anal Bioanal Chem. 2009 Dec;395(8):2559-67. doi: 10.1007/s00216-009-3159-0. Epub 2009 Oct 2.
A simple layer-by-layer method to coat the bacterial cells with gold and silver nanoparticles (AuNPs and AgNPs) for the acquisition of surface-enhanced Raman scattering (SERS) spectra is reported. First, the bacteria cell wall is coated with poly (allylamine hydrochloride) (PAH), a positively charged polymer, and then with citrate reduced Au or AgNPs. In order to increase the stability of the coating, another layer of PAH is prepared on the surface. The SEM and AFM images indicate that the nanoparticles are in the form of both isolated and aggregated nanoparticles on the bacterial wall. The coating of bacterial cells with AgNPs or AuNPs not only serves for their preparation for SERS measurement but also helps to visualize the coated of bacterial cells under the ordinary white-light microscope objective due to efficient light-scattering properties of Au and AgNPs. A comparative study single versus aggregates of bacterial cells is also demonstrated for possible single bacterial detection with SERS. The two bacteria that differ in shape and cell wall biochemical structure, Escherichia coli and Staphylococcus cohnii, Gram-negative and -positive, respectively, are used as models. The preliminary results reveal that the approach could be used for single bacterial cell identification.
本文报道了一种简单的层层法，用于将金和银纳米粒子（AuNPs 和 AgNPs）涂覆在细菌细胞表面，以获得表面增强拉曼散射（SERS）光谱。首先，细菌细胞壁涂覆带正电荷的聚合物聚（盐酸烯丙胺）（PAH），然后涂覆柠檬酸还原的 Au 或 AgNPs。为了提高涂层的稳定性，在表面再制备一层 PAH。SEM 和 AFM 图像表明，纳米粒子在细菌壁上呈孤立和聚集纳米粒子的形式。用 AgNPs 或 AuNPs 涂覆细菌细胞不仅可用于准备 SERS 测量，还由于 Au 和 AgNPs 的高效光散射特性，有助于在普通白光显微镜物镜下可视化涂覆的细菌细胞。还对单个细菌细胞与细菌细胞聚集体的对比研究进行了演示，以便可能通过 SERS 进行单个细菌的检测。使用形状和细胞壁生化结构不同的两种细菌（分别为革兰氏阴性菌和革兰氏阳性菌的大肠杆菌和凝固酶阴性葡萄球菌）作为模型。初步结果表明，该方法可用于单个细菌细胞的鉴定。
