scholarly journals Surface Enhanced Raman Spectroscopy of Lactoferrin Adsorbed on Silvered Porous Silicon Covered with Graphene

Biosensors ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 34 ◽  
Author(s):  
Sergey Zavatski ◽  
Nadia Khinevich ◽  
Kseniya Girel ◽  
Sergey Redko ◽  
Nikolai Kovalchuk ◽  
...  

We registered surface enhanced Raman scattering (SERS) spectra of the human lactoferrin molecules adsorbed on a silvered porous silicon (por-Si) from 10−6–10−18 M solutions. It was found that the por-Si template causes a negative surface potential of silver particles and their chemical resistivity to oxidation. These properties provided to attract positively charged lactoferrin molecules and prevent their interaction with metallic particles upon 473 nm laser excitation. The SERS spectra of lactoferrin adsorbed from 10−6 M solution were rather weak but a decrease of the concentration to 10−10 M led to an enormous growth of the SERS signal. This effect took place as oligomers of lactoferrin were broken down to monomeric units while its concentration was reduced. Oligomers are too large for a uniform overlap with electromagnetic field from silver particles. They cannot provide an intensive SERS signal from the top part of the molecules in contrast to monomers that can be completely covered by the electromagnetic field. The SERS spectra of lactoferrin at the 10−14 and 10−16 M concentrations were less intensive and started to change due to increasing contribution from the laser burned molecules. To prevent overheating the analyte molecules on the silvered por-Si were protected with graphene, which allowed the detection of lactoferrin adsorbed from the 10−18 M solution.

2014 ◽  
Vol 12 (s1) ◽  
pp. S12401-312404 ◽  
Author(s):  
Changwu Lü Changwu Lü ◽  
Jiajia Wang Jiajia Wang ◽  
Xiaoyi Lü Xiaoyi Lü ◽  
Zhenghong Jia Zhenghong Jia

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2508
Author(s):  
Osama Nasr ◽  
Jian-Ru Jiang ◽  
Wen-Shuo Chuang ◽  
Sheng-Wei Lee ◽  
Chih-Yen Chen

In this article, we demonstrate a facile, rapid, and practical approach to growing high-quality Cu2S nanosheets decorated with Ag nanoparticles (NPs) through the galvanic reduction method. The Ag/Cu2S nanosheets were efficiently applied to the surface-enhanced Raman scattering (SERS) and photocatalytic degradation applications. The photodegradation of RhB dye with the Ag/Cu2S nanosheets composites occurred at a rate of 2.9 times faster than that observed with the undecorated Cu2S nanosheets. Furthermore, the Ag/Cu2S nanosheets displayed highly sensitive SERS detection of organic pollutant (R6G) as low as 10−9 M. The reproducibility experiments indicated that the Ag/Cu2S nanosheets composites could be used for dual functionality in a new generation of outstandingly sensitive SERS probes for detection and stable photocatalysts.


2019 ◽  
Vol 9 (22) ◽  
pp. 4806 ◽  
Author(s):  
Ibrahim Khalil ◽  
Chia-Man Chou ◽  
Kun-Lin Tsai ◽  
Steven Hsu ◽  
Wageeh A. Yehye ◽  
...  

Metallic film-coated porous silicon (PSi) has been reported as a lucrative surface-enhanced Raman scattering (SERS) substrate. The solution-based fabrication process is facile and easy; however, it requires additional reducing agent and extra chemical treatment, as well as hinders the suitability as a reproducible SERS substrate due to irregular hot spot generation via irregular deposition of metallic nanocrystallites. To address this issue, we report a unique one-step electronic beam (e-beam) physical vapor deposition (PVD) method to fabricate a consistent layer of gold (Au) nanofilm on PSi. Moreover, to achieve the best output as a SERS substrate, PSi prepared by electrochemical etching was used as template to generate an Au layer of irregular surface, offering the surface roughness feature of the PSi–Au thin film. Furthermore, to investigate the etching role and Au film thickness, Au-nanocrystallites of varying thickness (5, 7, and 10 nm) showing discrete surface morphology were characterized and evaluated for SERS effect using Rhodamine 6G (R6G). The SERS signal of R6G adsorbed on PSi–Au thin film showed a marked enhancement, around three-fold enhancement factor (EF), than the Si–Au thin film. The optimal SERS output was obtained for PSi–Au substrate of 7 nm Au film thickness. This study thus indicates that the SERS enhancement relies on the Au film thickness and the roughness feature of the PSi–Au substrate.


2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940087
Author(s):  
A. Panarin ◽  
P. Mojzes ◽  
B. Ranishenka ◽  
S. Terekhov

The degradation of the Surface-enhanced Raman scattering (SERS) signal under laser illumination during spectral measurements is typically observed. To improve the stability of the SERS spectra intensity, hybrid plasmonic structures involving graphene-based protective layers were formed. An observation of the time evolution of the characteristic peak from analyte molecules indicates that the graphene coating can be used to improve the stability of the SERS signal.


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