title: One-step fabrication of sub-10-nm plasmonic nanogaps for reliable SERS sensing of microorganisms.
abstract: 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.
authors: Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China.
authors: Jing
authors: J
authors: Chen
authors: Gaowu
authors: G
authors: Qin
authors: Jiansheng
authors: J
authors: Wang
authors: Jiangyu
authors: J
authors: Yu
authors: Bo
authors: B
authors: Shen
authors: Song
authors: S
authors: Li
authors: Yuping
authors: Y
authors: Ren
authors: Liang
authors: L
authors: Zuo
authors: Wen
authors: W
authors: Shen
authors: Biswajit
authors: B
authors: Das
mesh_terms: D001407:Bacillus / Q000737:chemistry / Q000302:isolation & purification*; D015374:Biosensing Techniques / Q000295:instrumentation; D004867:Equipment Design; D004926:Escherichia coli / Q000737:chemistry / Q000302:isolation & purification*; D049329:Nanostructures / Q000737:chemistry*; D015203:Reproducibility of Results; D012235:Rhodamines / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D013499:Surface Properties
chemical_list: D012235:Rhodamines; C026188:rhodamine 6G; D012834:Silver