Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291-Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
ACS Appl Mater Interfaces. 2018 Jan 10;10(1):290-295. doi: 10.1021/acsami.7b16182. Epub 2017 Dec 22.
Plasmonic alloy has attracted much interest in tailoring localized surface plasmon resonance (LSPR) for recent biosensing techniques. In particular, paper-based plasmonic substrates allow capillary-driven lateral flow as well as three-dimensional metal nanostructures, and therefore they become actively transferred to LSPR-based biosensing such as surface-enhanced Raman spectroscopy (SERS) or metal-enhanced fluorescence (MEF). However, employing plasmonic alloy nanoislands on heat-sensitive substrate is still challenging, which significantly inhibits broad-range tailoring of the plasmon resonance wavelength (PRW) for superior sensitivity. Here we report paper-based plasmonic substrate with plasmonic alloy of Au/Ag nanocomposites for highly sensitive MEF and SERS biosensing applications. The nanofabrication procedures include concurrent deposition of Au and Ag below 100 °C without any damage on cellulose fibers. The Au/Ag nanocomposites feature nanoplasmonic alloy with single plasmon peak as well as broad-range tunability of PRW by composition control. This paper-based plasmonic alloy substrate enables about twofold enhancement of fluorescence signals and selective MEF after paper chromatography. The experimental results clearly demonstrate extraordinary enhancement in SERS signals for picomolar detection of folic acid as a cancer biomarker. This new method provides huge opportunities for fabricating plasmonic alloy on heat-sensitive substrate and biosensing applications.
等离子体合金在为最近的生物传感技术定制局域表面等离子体共振 (LSPR) 方面引起了广泛关注。特别是基于纸张的等离子体基底允许毛细驱动的横向流动以及三维金属纳米结构，因此它们被积极地转移到基于 LSPR 的生物传感，如表面增强拉曼光谱 (SERS) 或金属增强荧光 (MEF)。然而，在热敏基底上使用等离子体合金纳米岛仍然具有挑战性，这极大地限制了等离子体共振波长 (PRW) 的广泛调整，以实现更高的灵敏度。在这里，我们报告了一种基于纸张的等离子体基底，其具有 Au/Ag 纳米复合材料的等离子体合金，可用于高度敏感的 MEF 和 SERS 生物传感应用。纳米制造过程包括在 100°C 以下同时沉积 Au 和 Ag，而不会对纤维素纤维造成任何损坏。Au/Ag 纳米复合材料具有单等离子体峰的纳米等离子体合金以及通过成分控制实现的 PRW 的宽范围可调谐性。这种基于纸张的等离子体合金基底可使荧光信号增强约两倍，并在纸层析后选择性地进行 MEF。实验结果清楚地证明了在 picomolar 检测叶酸作为癌症生物标志物时 SERS 信号的非凡增强。这种新方法为在热敏基底上制造等离子体合金和生物传感应用提供了巨大的机会。
