Simultaneous trapping-and-detecting surface-enhanced Raman spectroscopy by self-aligned hot-spots

2016 ◽  
Author(s):  
Soonwoo Hong ◽  
On Shim ◽  
Hyosung Kwon ◽  
Yeonho Choi
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nan Chen ◽  
Ting-Hui Xiao ◽  
Zhenyi Luo ◽  
Yasutaka Kitahama ◽  
Kotaro Hiramatsu ◽  
...  

Abstract Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for vibrational spectroscopy as it provides several orders of magnitude higher sensitivity than inherently weak spontaneous Raman scattering by exciting localized surface plasmon resonance (LSPR) on metal substrates. However, SERS can be unreliable for biomedical use since it sacrifices reproducibility, uniformity, biocompatibility, and durability due to its strong dependence on “hot spots”, large photothermal heat generation, and easy oxidization. Here, we demonstrate the design, fabrication, and use of a metal-free (i.e., LSPR-free), topologically tailored nanostructure composed of porous carbon nanowires in an array as a SERS substrate to overcome all these problems. Specifically, it offers not only high signal enhancement (~106) due to its strong broadband charge-transfer resonance, but also extraordinarily high reproducibility due to the absence of hot spots, high durability due to no oxidization, and high compatibility to biomolecules due to its fluorescence quenching capability.


ACS Nano ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. 528-536 ◽  
Author(s):  
Xiang Wang ◽  
Maohua Li ◽  
Lingyan Meng ◽  
Kaiqiang Lin ◽  
Jiamin Feng ◽  
...  

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1554 ◽  
Author(s):  
Yaqi Huang ◽  
Dajie Lin ◽  
Mengting Li ◽  
Dewu Yin ◽  
Shun Wang ◽  
...  

A highly sensitive immunoassay of biomarkers has been achieved using 4-mercaptobenzoic acid-labeled Ag@Au core–shell porous nanocage tags and α-fetoprotein immuno-sensing chips. The Ag@Au porous nanocages were uniquely synthesized by using an Ag core as a self-sacrificial template and reducing agent, where the slow reaction process led to the formation of a porous Au layer. The size of the remaining Ag core and surface roughness of the Au shell were controlled by adjusting the chloroauric acid concentration. The porous cage exhibited excellent surface-enhanced Raman spectroscopy (SERS) activity, presumably due to a synergetic interaction between newly generated hot spots in the rough Au shell and the retained SERS activity of the Ag core. Using α-fetoprotein as a model analyte for immunoassay, the SERS signal had a wide linear range of 0.20 ng mL−1 to 500.0 ng mL−1 with a detection limit of 0.12 ng mL−1. Without the need of further signal amplification, the as-prepared Ag@Au bimetallic nanocages can be directly used for highly sensitive SERS assays of other biomarkers in biomedical research, diagnostics, etc.


2021 ◽  
Author(s):  
Chigusa Matsumoto ◽  
Masao Gen ◽  
Atsushi Matsuki ◽  
Takafumi Seto

Abstract We report a spray-drying method to fabricate silver nanoparticle (AgNP) aggregates for application in surface-enhanced Raman spectroscopy (SERS). A custom-built system was used to fabricate AgNP aggregates of three sizes, 48, 86, and 218 nm, from drying droplets containing AgNPs atomized from an AgNP suspension. Sample solutions of Rhodamine B (RhB) at 10–6, 10–8, and 10–10 M concentrations were dropped onto the AgNP aggregates as probe molecules to examine the enhancement of the Raman signals of the RhB. The ordering of the analytical enhancement factors (AEFs) by aggregate size at a given RhB concentration was 86 nm > 218 nm > 48 nm. The AEFs of the 86 nm AgNP aggregates were higher than those of the 218-nm aggregates, although the 218-nm aggregates had more hot spots where Raman enhancement occurred. This finding was attributable to the deformation and damping of the electron cloud in the highly aggregated AgNPs, reducing the sensitivity for Raman enhancement. When RhB was premixed with the AgNP suspension prior to atomization, the AEFs at 10–8 M RhB rose ~100-fold compared to those in the earlier experiments (the post-dropping route). This significant enhancement was probably caused by the increased opportunity for the trapping of the probe molecules in the hot spots.


RSC Advances ◽  
2019 ◽  
Vol 9 (56) ◽  
pp. 32535-32543 ◽  
Author(s):  
Jemima A. Lartey ◽  
John P. Harms ◽  
Richard Frimpong ◽  
Christopher C. Mulligan ◽  
Jeremy D. Driskell ◽  
...  

Systematic combination of plasmonic nanoparticles on a paper-based substrate introduces SERS-based signal-enhancement environments via interparticle coupling and hot spots.


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