Identification of Salmonella Serovars before and after Ultraviolet Light Irradiation by Fourier Transform Infrared (FT-IR) Spectroscopy and Chemometrics

CISS-Based Label-Free Novel Electrochemical Impedimetric Detection of UVC-Induced DNA Damage

“…The peak at 1647 cm –1 corresponds to the cytosine while those obtained in the range of 1515–1650 cm –1 match with C=O, C=N, C=C stretching, and exocyclic −NH 2 bending vibrations in the DNA bases. 35 − 37 Similarly, the peak observed at 1660 cm –1 corresponds to the C4=O4 vibration in thymine. 36 The characteristic peaks of the different functional groups of DNA found in the FT-IR spectra confirm the assembly of the ds-DNA monolayer on Ni/Au thin film successfully.…”

“…The difference spectra were obtained by subtracting the FT-IR spectrum of unexposed DNA from that of UVC-exposed ds-DNA to detect FT-IR marker bands that are indicative of dimerization (Figure b). After the exposure of ds-DNA to UVC radiation, two major pyrimidine photoproducts are formed in the ds-DNA, such as CPDs and 6–4PPs. ,, However, 6–4 PPs can be neglected because of very low yields in comparison to CPDs. Furthermore, UVC-exposed ds-DNA immobilized on Ni/Au thin film resulted in the emergence of numerous positive and negative differences in bands, which may be ascribed to the formation of thymine dimers.…”

“…After the exposure of ds-DNA to UVC radiation, two major pyrimidine photoproducts are formed in the ds-DNA, such as CPDs and 6–4PPs. 37 , 49 , 50 However, 6–4 PPs can be neglected because of very low yields in comparison to CPDs. Furthermore, UVC-exposed ds-DNA immobilized on Ni/Au thin film resulted in the emergence of numerous positive and negative differences in bands, which may be ascribed to the formation of thymine dimers.…”

Specific optical-based biosensor to rapid detection of Salmonella Typhimurium using FTIR: evaluation in natural orange juice, as an application in food products

“…Five differentSalmonella Typhimurium concentrations could be detected in natural orange juice samples (100, 250, 500, 750, and 1000 CFU/mL). According toGómez et al (2021) andMuntean et al, (2021), after the detection of Salmonella, a FTIR band was identified as characteristic at 1030 cm −1 , this band is related to bonds (P=O, C=O, P-O-C, and P-O-P) present in the bacterial cell membrane components like phospholipids and glycerophospholipids(Dalebroux et al, 2015); as well as the sugar phosphate backbone from DNA(Heaney and Graeff-Armas, 2018), this wavenumber value was considered to confirm the detection of the bacteria on a-Si biosensors. In Figure2, FTIR spectra corresponding to the detection of microorganism in the juice are shown; lower spectrum corresponds to a-Si biosensor prior detection, furthermore, orange juice FTIR spectrum was used as control in this study, since this food contains some compounds like vitamin C, carbohydrates (fructose, glucose, sucrose), proteins, and dietary fiber(Chanson-Rolle et al, 2016) that could interfere in the identification of the FTIR Salmonella band detection, despite this, no similar bands are observed when comparing the orange juice FTIR spectrum with the microorganism detection FTIR spectra.…”