Biosensors and Bioelectronics 2013-06-15

One-step fabrication of sub-10-nm plasmonic nanogaps for reliable SERS sensing of microorganisms.

Jing Chen, Gaowu Qin, Jiansheng Wang, Jiangyu Yu, Bo Shen, Song Li, Yuping Ren, Liang Zuo, Wen Shen, Biswajit Das

文献索引：Biosens. Bioelectron. 44 , 191-7, (2013)

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摘要

Nanoscale gaps in noble metal films can produce intense electromagnetic enhancement. When Raman-active molecules are positioned in these regions, their surface-enhanced Raman scattering (SERS) signals can be dramatically enhanced. However, the lack of convenient and reliable fabrication methods with ultrasmall nanogaps (<10 nm) severely block the application of SERS. Here, we propose a cost-effective and reproducible technique to fabricate the large-area Ag SERS-active substrates which are full of the high-density, sub-10-nm nanogaps by high pressure sputtering, and the enhancement factor (EF) is testified to improve by 10(3) times compared to the continuous Ag film with a smooth surface (the roughness is 0.5 nm) and without nanogaps. Since there are no chemicals used during fabrication, this substrate has a clean surface, which is crucial for acquiring reliable SERS spectra. This SERS-active substrate has then been applied to identify a series of microorganisms, and excellent, reproducible SERS spectra were obtained. Finally, a set of piecewise-linear equations is provided according to the correlation between SERS intensity and rhodamine 6G (R6G) concentration, and the detection limit is calculated to be 0.2×10(-8)M. These results suggest that the high pressure sputtering is an excellent, reliable technique for fabricating sub-10-nm plasmonic nanogaps, and the SERS-based methodology is very promising for being used in biological sensing field.Copyright © 2013 Elsevier B.V. All rights reserved.