Volume 19, Issue 1 (Journaloflasersinmedicine 2022)
lmj 2022, 19(1): 25-32 |
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Eskandari V, Sharifi N. Plasmonic Sensors for Identification and Determination of Escherichia Coli Pathogenic bacterial concentration. lmj 2022; 19 (1) :25-32
URL: http://icml.ir/article-1-560-en.html
URL: http://icml.ir/article-1-560-en.html
Assistant Professor, Photonic and Plasma group, Physics Department, University of Kashan, Kashan 8731753153, Iran
Abstract: (978 Views)
Background: Surface-enhanced Raman spectroscopy (SERS) is one of the most efficient methods for small-scale detection and even single-molecule detection. When different species are close to the metal surface or are physically absorbed on the nanostructures, the Raman signal intensities increase due to the interaction of the silver surface species and plasmons. Escherichia coli is found in many foods and could easily grow so it is important to identify it in the food and agriculture industries. Escherichia coli is found in many foods and can easily grow. Therefore, the control of Escherichia coli in the food and agricultural industries is of particular interest, so that the identification of this bacterium can be suggested using the SERS technique that is relatively simple and inexpensive compared to other techniques. Since silver nanostructures improves the Raman signal from different molecules due to surface plasmon resonance and light scattering, in this study, silvery substrates have been fabricated and obtained as plasmonic sensors to detect different concentrations of Escherichia coli.
Materials and Methods: In this experimental study, for the purpose of fabricating a plasmonic sensor, silvery substrates were synthesized by a simple chemical method; and detection of Escherichia coli was performed using silvery substrates and non-destructive Raman spectroscopy.
Results: Plasmon peak at around 410 confirmed the formation of silver nanoparticles. The field emission electron microscopy (FESEM) image shows more silver nanoparticles on the silvery substrate have sizes between 1400 and 1500 nm. The roughness of the silvery substrates causes the light to be scattered. When Gelatin was put on the plasmonic substrates, the vibrations of Gelatin molecules are amplified due to the surface plasmon resonance of the smaller nanoparticles as well as the light scattering of the larger silver and gold particles. The SERS spectrum intensities of these two substrates increase with respect to their Raman spectra. Surface plasmon resonance of silver nanoparticles as well as light scattering from larger agglomerated silver particles enhance the molecular vibrations of Escherichia coli. By calibrating the intensity of molecular vibrations in terms of bacterial concentration, a linear relationship was obtained from which the concentration of the bacterial could be determined by measuring SERS spectra.
Conclusion: Raman spectroscopy improves the Raman signals of Escherichia coli due to the resonance of surface plasmons of silver nanoparticles and the light scattering from larger silver particles. As the bacterial concentration decreases, the SERS signals are attenuated by the decrease in the number of molecular vibrations in which rapid and convenient detection of Escherichia coli could be performed up to a concentration of 102 cfumL-1 using the silvery substrates. In addition, by calibration, the concentration of Escherichia coli could be determined using silvery substrates and Raman spectroscopy.
Materials and Methods: In this experimental study, for the purpose of fabricating a plasmonic sensor, silvery substrates were synthesized by a simple chemical method; and detection of Escherichia coli was performed using silvery substrates and non-destructive Raman spectroscopy.
Results: Plasmon peak at around 410 confirmed the formation of silver nanoparticles. The field emission electron microscopy (FESEM) image shows more silver nanoparticles on the silvery substrate have sizes between 1400 and 1500 nm. The roughness of the silvery substrates causes the light to be scattered. When Gelatin was put on the plasmonic substrates, the vibrations of Gelatin molecules are amplified due to the surface plasmon resonance of the smaller nanoparticles as well as the light scattering of the larger silver and gold particles. The SERS spectrum intensities of these two substrates increase with respect to their Raman spectra. Surface plasmon resonance of silver nanoparticles as well as light scattering from larger agglomerated silver particles enhance the molecular vibrations of Escherichia coli. By calibrating the intensity of molecular vibrations in terms of bacterial concentration, a linear relationship was obtained from which the concentration of the bacterial could be determined by measuring SERS spectra.
Conclusion: Raman spectroscopy improves the Raman signals of Escherichia coli due to the resonance of surface plasmons of silver nanoparticles and the light scattering from larger silver particles. As the bacterial concentration decreases, the SERS signals are attenuated by the decrease in the number of molecular vibrations in which rapid and convenient detection of Escherichia coli could be performed up to a concentration of 102 cfumL-1 using the silvery substrates. In addition, by calibration, the concentration of Escherichia coli could be determined using silvery substrates and Raman spectroscopy.
Keywords: Escherichia coli, Silver nanoparticle, Silvery substrate, Plasmonic Sensor, Raman Spectroscopy
Educational: Research |
Subject:
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Received: 2022/08/5 | Accepted: 2022/09/14 | Published: 2022/10/2
Received: 2022/08/5 | Accepted: 2022/09/14 | Published: 2022/10/2
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