Surface-enhanced Raman spectroscopy for monitoring antibacterial activity of imidazole derivative (1-benzyl-3-(sec­butyl)-1H-imidazole-3-ium bromide) against Bacillus subtilis and Escherichia coli.

BACKGROUND: Bacterial resistance against antibiotics remains a challenge and Raman Spectroscopy (SERS) may provide critical information concerning this. OBJECTIVES: In the current study, surface enhances Raman spectroscopy (SERS) has been used to determine the biochemical changes induced during the antibacterial activity of the in house synthesized imidazole derivative (1-benzyl-3-(sec­butyl)-1H-imidazole-3-ium bromide) in comparison to commercially available drugs (fasygien) against both gram-positive and gram-negative bacteria. METHODS: For this purpose, the antibacterial activity of this compound was assessed on Bacillus subtilis and Escherichia coli. The SERS spectral changes are detected which can be associated with the biochemical changes in the bacterial cells as a result of the application of both drugs, including fasygien and the imidazole derivative drug demonstrating the technique's potential for analyzing the antibacterial activities of drug candidates. RESULTS: The chemometric techniques such as Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) were performed for the differentiation of SERS spectral data sets of unexposed, exposed with imidazole derivative and commercially available antibacterial drugs for two different bacteria including E. coli and Bacillus. CONCLUSIONS: PCA was found helpful for the qualitative differentiation of all drug-treated E. coli and Bacillus in the form of separate clusters of spectral data sets and PLS-DA discriminated the unexposed and the exposed bacteria with imidazole derivative and commercially available drug with 93% sensitivity and 96% specificity for Bacillus and with 90% sensitivity and 89% specificity for E. coli.

Surface-enhanced Raman spectroscopic analysis of centrifugally filtered blood serum samples of hepatitis C patients.

BACKGROUND: Raman spectroscopy is able to analyze non-invasively, disease related to body fluids. OBJECTIVES: For the qualitative and quantitative analysis of HCV serum samples surface-enhanced Raman spectroscopy (SERS) based method is developed. METHOD: Surface-enhanced Raman spectroscopy (SERS) technique is employed for analysis of filtrate portions of blood serum samples of hepatitis C virus (HCV) infected patients and healthy ones by using 50 kDa centrifugal filter device. The filtrate portions of the serum obtained in this way contain proteins smaller than 50 kDa and removal of bigger size protein which allows to acquire SERS spectral features of smaller proteins more effectively which are probably associated with Hepatitis C infection. Moreover, SERS spectral features of the filtrates of different level of viral load including low, medium and high viral loads are compared with SERS spectral features of the filtrate portions of healthy/control serum samples. SERS spectral data sets of different samples are further analyzed by using multivariate data analysis techniques such as principal component analysis (PCA) and partial least square regression (PLSR). Some SERS spectral features are solely observed in the filtrate portions of the serum samples of hepatitis C and their intensities are increased as the level of viral load increases and might be used for HCV diagnosis. RESULTS: PCA was found helpful for differentiation of SERS spectral data sets of filtrate portions of the serum samples of hepatitis C and healthy persons. The PLSR model helped for the quantification of viral loads in the unknown serum samples with 99% accuracy.