Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA.
Biosens Bioelectron. 2012 Jan 15;31(1):130-6. doi: 10.1016/j.bios.2011.10.006. Epub 2011 Oct 12.
Multifunctional magnetic-plasmonic Fe(3)O(4)-Au core-shell nanoparticles (Au-MNPs) were prepared for simultaneous fast concentration of bacterial cells by applying an external point magnetic field, and sensitive detection and identification of bacteria using surface-enhanced Raman spectroscopy (SERS). We demonstrated that a spread of a 10 μL drop of a mixture of 10(5) cfu/mL bacteria and 3 μg/mL Au-MNPs on a silicon surface can be effectively condensed into a highly compact dot within 5 min by applying an external point magnetic field, resulting in 60 times more concentrated bacteria in the dot area than on the spread area without concentration. Surrounded by dense uniformly packed Au-MNPs, bacteria can be sensitively and reproducibly detected directly using SERS. The principle component analysis (PCA) showed that three different Gram-negative bacterial strains can be clearly differentiated. We also demonstrated that the condensed multifunctional Au-MNPs dot can be used as a highly sensitive SERS-active substrate and a limit of detection better than 0.1 ppb was obtained in detection of small molecules such as 4-mercaptopyrine. This novel platform significantly simplifies the concentration and detection process, which holds great promise for applications in food safety, environmental monitoring, medical diagnoses, and chemical and biological threat detections.
多功能磁性等离子体 Fe(3)O(4)-Au 核壳纳米粒子（Au-MNPs）被制备用于通过施加外部点磁场同时快速浓缩细菌细胞，并使用表面增强拉曼光谱（SERS）灵敏地检测和识别细菌。我们证明，通过施加外部点磁场，将 10 μL 滴的 10(5) cfu/mL 细菌和 3 μg/mL Au-MNPs 的混合物散布在硅表面上可以有效地在 5 分钟内凝结成高度紧凑的点，从而使点区域内的细菌浓缩 60 倍比没有浓缩的散布区域。被密集均匀包裹的 Au-MNPs 包围，细菌可以直接使用 SERS 进行灵敏和可重复的检测。主成分分析（PCA）表明，可以清楚地区分三种不同的革兰氏阴性细菌菌株。我们还证明，浓缩的多功能 Au-MNPs 点可以用作高度灵敏的 SERS 活性基底，并且在检测小分子（如 4-巯基嘧啶）时可以获得优于 0.1 ppb 的检测限。这个新平台大大简化了浓缩和检测过程，在食品安全、环境监测、医疗诊断以及化学和生物威胁检测等领域具有广阔的应用前景。
