Spectroscopic characterization of biological agents using FTIR, normal Raman and surface-enhanced Raman spectroscopies

Abstract

FTIR, Raman spectroscopy and Surface Enhanced Raman Scattering (SERS) requires a minimum of sample allows fast identification of microorganisms. The use of this technique for characterizing the spectroscopic signatures of these agents and their stimulants has recently gained considerable attention due to the fact that these techniques can be easily adapted for standoff detection from considerable distances. The techniques also show high sensitivity and selectivity and offer near real time detection duty cycles. This research focuses in laying the grounds for the spectroscopic differentiation of Staphylococcus spp., Pseudomonas spp., Bacillus spp., Salmonella spp., Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, and E. coli, together with identification of their subspecies. In order to achieve the proponed objective, protocols to handle, cultivate and analyze the strains have been developed. Spectroscopic similarities and marked differences have been found for Spontaneous or Normal Raman spectra and for SERS using silver nanoparticles have been found. The use of principal component analysis (PCA), discriminate factor analysis (DFA) and a cluster analysis were used to evaluate the efficacy of identifying potential threat bacterial from their spectra collected on single bacteria. The DFA from the bacteria Raman spectra show a little discrimination between the diverse bacterial species however the results obtained from the SERS demonstrate to be high discrimination technique. The spectroscopic study will be extended to examine the spores produced by selected strains since these are more prone to be used as Biological Warfare Agents due to their increased mobility and possibility of airborne transport. Micro infrared spectroscopy as well as fiber coupled FTIR will also be used as possible sensors of target compounds.

Steel Wire Mesh as a Thermally Resistant SERS Substrate

“…As can be seen in the Figure 7 , the obtained SERS spectra of both bacteria species show major peaks at around 650, 725, 960, 1000, 1100, 1330, 1375, 1460 and 1590 cm −1 and less intense bands at around 565, 780, 850, 1030, 1275 cm −1 . The peak at around 565 cm −1 may originate from C–O–C ring deformation [ 53 ] or C–C skeletal vibration [ 54 ], while the one at 650 cm −1 —from C–S stretching in methionine [ 55 ] and/or C–C twisting mode of tyrosine [ 56 ]. The most intense band, located at 725 cm −1 , can be assigned to adenine derivatives [ 57 ].…”

“…The phosphodioxy group ( ) from nucleic acids can be observed in the spectrum in a form of the peak at 1092 cm −1 [ 62 ], while the amide III and CH 2 wagging vibrations from glycine backbone and proline sidechains can be detected as the band at 1275 cm −1 [ 63 ]. Finally, the bands at around 1333, 1375, 1460 and 1590 cm −1 can be assigned to adenine [ 64 ], COO stretching [ 65 ], CH 2 bending [ 53 ] and C=C olefinic stretching [ 60 ], respectively.…”

Highly efficient SERS-based detection of cerebrospinal fluid neopterin as a diagnostic marker of bacterial infection

“…This band is observed in many types of bacterial species like Escherichia coli, Salmonella enterica, Staphylococcus epidermidis, Staphylococcus aureus , and Bacillus megaterium [ 33 , 55 ]. This band is due to the C–N stretching mode vibration of the adenine of lipid layer in the cell wall or to the breathing mode of the purine ring [ 59 , 60 ]. Jarvis et al assigned this band to the vibration of the glycosidic ring mode from cell wall components [ 61 ].…”

“…The SERS spectrum of this bacterium also indicates peaks assigned to amide III (1252 cm −1 ) and CH 2 vibrations (1450 cm −1 ) [ 59 ]. Table S1 (see ESM) shows band assignments for N. meningitidis.…”

Photovoltaic cells as a highly efficient system for biomedical and electrochemical surface-enhanced Raman spectroscopy analysis

“…The band at 1093 cm À1 is assigned to phosphodioxy group (PO 2 À ) in nucleic acids, 80 while the amide III and CH 2 wagging vibrations from the glycine backbone and proline sidechains can be observed in the spectrum in the form of 1275 cm À1 . 81 The SERS signatures at 1333, 1382, 1450, and 1588 cm À1 originate from adenine, 82 COO stretching, 83 CH 2 bending 72 and C]C olenic stretching, 79 respectively. Fig.…”