Aminopyrine Raman spectral features characterised by experimental and theoretical methods: toward rapid SERS detection of synthetic antipyretic–analgesic drug in traditional Chinese medicine
“…S2 c. It can be observed that SERS intensity of the peak at 1572 cm −1 remained unchanged within 1 day, and the peak intensity decreased to 50 % on the 5th day and 10 % on the 7th day. Thus, Au@AgNPs had good stability for SERS measurements within 1 day, which was consistent with the previous study ( Zheng et al, 2014 ). Fig.…”
“…S2 c. It can be observed that SERS intensity of the peak at 1572 cm −1 remained unchanged within 1 day, and the peak intensity decreased to 50 % on the 5th day and 10 % on the 7th day. Thus, Au@AgNPs had good stability for SERS measurements within 1 day, which was consistent with the previous study ( Zheng et al, 2014 ). Fig.…”
“…is considered, 36 where Cnorm and CSERS are the concentration of carbofuran used in the normal Raman and SERS measurements, respectively. ISERS and Inorm are the intensity of the peak at 1201 cm -1 from SERS and normal Raman, respectively.…”
Section: Diazo-coupling Based Sers For Carbofuran Detectionmentioning
In this research, a sensitive and selective method for detecting one of the most toxic insecticides, "carbofuran", in rice and soybean is presented. This method is based on the coupling reaction of diazonium ion combined with a surface-enhanced Raman scattering technique. Diazonium ion produced from p-aminothiophenol reacts specifically with carbofuran phenol from the hydrolysis of carbofuran. The generated azo compounds attach to the surface of silver nanoparticles via the Ag-S bond. Therefore, a strong Raman intensity can be obtained. The concentration of carbofuran can be determined by following the intensity of the peak at 1201 cm -1 , attributed to the C-N stretching vibration of the azo compound. The result shows a good linear correlation (R 2 = 0.9786) against carbofuran concentrations (0.1 -5 ppm) with a detection limit of 0.452 ppm. Our proposed protocol is insignificantly influenced by various common interferences. Moreover, this method has been successfully validated to determine carbofuran concentrations in rice and soybean with detection limits of 0.446 and 0.520 ppm, respectively.
“…The characteristic peaks of R6G at 614 and 1310 cm −1 corresponded to the in-plane C–C–C bending and C–O–C bending, respectively, and the peaks at 771 and 1125 cm −1 could be assigned to C–H out-of-plane and in-plane bending modes. 52 For comparison, the performance of the prepared substrate was calculated in terms of enhancement factor (EF) using the following formula: 53 , 54 where I SERS and I Normal are the intensities of the characteristic peaks of R6G from SERS and normal Raman spectra and C SERS and C Normal are the corresponding concentrations, respectively. The EF for core-shell nanoparticles was calculated to be 3.7 × 10 6 , which was 200 times higher than gold nanoparticles (1.837 × 10 4 ).…”
Detection of bioactive metabolites produced by bacteria is important for identifying biomarkers for infectious diseases. In this study, a surface-enhanced Raman spectroscopy-based technique was developed for the detection of bioactive metabolite indole produced by Escherichia coli in biological media. The use of highly sensitive Au@Ag core-shell nanoparticles resulted in the detection of indole concentration as low as 0.0886 mM in standard solution. The supplementation of growth media with 5 mM of exogenous tryptophan resulted in the production of a maximum yield of indole of 3.139 mM by E. coli O157:H7 at 37 °C. The growth of bacterial cells was reduced from 47.73 × 108 to 1.033 × 106 CFU/mL when the cells were grown in 0 and 10 mM exogenous tryptophan, respectively. The amount of indole in the Luria-Bertani (LB) media had an inverse correlation with the growth of cells, which resulted in a 3-log reduction in the colony-forming unit when the indole concentration in the media was 20 times higher than normal. This work demonstrates that surface-enhanced Raman spectroscopy is an effective and highly sensitive method for rapid detection of bioactive metabolites in biological matrix.
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