Electromagnetic Coupling Effect for Surface-enhanced Raman Spectroscopy and Tip-enhanced Raman Spectroscopy

2010 ◽  
Author(s):  
Bin Ren ◽  
Zheng Liu ◽  
Xiang Wang ◽  
Zhi-Lin Yang ◽  
Zhong-Qun Tian ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Coupling Effect ◽  
Electromagnetic Coupling ◽  
Surface Enhanced Raman Spectroscopy ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Tip Enhanced Raman Spectroscopy

Improving Sensitivity and Reproducibility of SERS Sensing in Microenvironments Using Individual, Optically Trapped Surface-Enhanced Raman Spectroscopy(SERS) Probes

2016 ◽  
Vol 71 (2) ◽  
pp. 279-287 ◽  
Author(s):  
Pietro Strobbia ◽  
Adam Mayer ◽  
Brian M Cullum
Keyword(s):  
Raman Spectroscopy ◽  
Optical Tweezers ◽  
Surface Enhanced Raman Spectroscopy ◽  
High Signal ◽  
Specific Information ◽  
Laser Fluences ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Trapped Surface ◽  
Tip Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) sensors offer many advantages for chemical analyses, including the ability to provide chemical specific information and multiplexed detection capability at specific locations. However, to have operative SERS sensors for probing microenvironments, probes with high signal enhancement and reproducibility are necessary. To this end, dynamic enhancement of SERS (i.e., in-situ amplification of signal-to-noise and signal-to-background ratios) from individual probes has been explored. In this paper, we characterize the use of optical tweezers to amplify SERS signals as well as suppress background signals via trapping of individual SERS active probes. This amplification is achieved through a steady presence of a single “hot” particle in the focus of the excitation laser. In addition to increases in signal and concomitant decreases in non-SERS backgrounds, optical trapping results in an eightfold increase in the stability of the signal as well. This enhancement strategy was demonstrated using both single and multilayered SERS sub-micron probes, producing combined signal enhancements of 24-fold (beyond the native 106 SERS enhancement) for a three-layered geometry. The ability to dynamically control the enhancement offers the possibility to develop SERS-based sensors and probes with tailored sensitivities. In addition, since this trapping enhancement can be used to observe individual probes with low laser fluences, it could offer particular interest in probing the composition of microenvironments not amenable to tip-enhanced Raman spectroscopy or other scanning probe methods (e.g., intracellular analyses, etc.).

Bacterial detection and differentiation via direct volatile organic compound sensing with surface enhanced Raman spectroscopy

2017 ◽  
Author(s):  
Caitlin S. DeJong ◽  
David I. Wang ◽  
Aleksandr Polyakov ◽  
Anita Rogacs ◽  
Steven J. Simske ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bacterial Infections ◽  
Direct Detection ◽  
Point Of Care ◽  
Surface Enhanced Raman Spectroscopy ◽  
E Coli ◽  
Recent Emergence ◽  
Surface Enhanced ◽  
Volatile Organic ◽  
Surface Enhanced Raman

Through the direct detection of bacterial volatile organic compounds (VOCs), via surface enhanced Raman spectroscopy (SERS), we report here a reconfigurable assay for the identification and monitoring of bacteria. We demonstrate differentiation between highly clinically relevant organisms: <i>Escherichia coli</i>, <i>Enterobacter cloacae</i>, and <i>Serratia marcescens</i>. This is the first differentiation of bacteria via SERS of bacterial VOC signatures. The assay also detected as few as 10 CFU/ml of <i>E. coli</i> in under 12 hrs, and detected <i>E. coli</i> from whole human blood and human urine in 16 hrs at clinically relevant concentrations of 10<sup>3</sup> CFU/ml and 10<sup>4</sup> CFU/ml, respectively. In addition, the recent emergence of portable Raman spectrometers uniquely allows SERS to bring VOC detection to point-of-care settings for diagnosing bacterial infections.

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