Surface-enhanced Raman scattering of Ethyl carbamate adsorbed on Ag20 cluster: Enhancement mechanism

Abstract

The normal and surface-enhanced Raman scattering of EC are studied by using the M06-2X functional. Different contributions to Raman enhancements of EC adsorbed on Ag 20 cluster are analyzed in detail to explore the enhancement mechanism. The adsorption of EC on Ag 20 cluster involves the static chemical enhancement with enhancements factor (EF) of 10 by forming a new EC-Ag 20 complex. The charge-transfer enhancement with EF of 10 4 is found when a 352nm wavelength, corresponding to the absorption maximum of EC-Ag 20 complex, is taken as an incident light. The electromagnetic enhancement EF of 3.6×10 6 due to the localized surface plasmon resonance (LSPR) of Ag nanosphere at the same excitation wavelength are acquired by the discrete dipole approximation (DDA) method. The combined effect of the chemical and electromagnetic enhancement results in the total relative enhancements factor up to 3.6×10 10. The enhancement mechanisms are successfully explained by the combination of ab initio calculation and discrete dipole appropriation method.

β-Amyloid Peptide 1–42-Conjugated Magnetic Nanoparticles for the Isolation and Purification of Glycoproteins in Egg White

“…The characteristic absorption peaks at 213 and 275 cm –1 were attributed to Fe–O in Fe 3 O 4 . Meanwhile, the characteristic absorption peaks of Aβ 1–42 were also observed in the Raman spectrum of Aβ 1–42 @MNP, wherein the peaks at 672, 1343, and 1572 cm –1 were attributed to the C–N, C–H, and N–H bonds, demonstrating that Aβ 1–42 @MNP had been coupled to the surface of the magnetic nanoparticles …”

“…Meanwhile, the characteristic absorption peaks of Aβ 1−42 were also observed in the Raman spectrum of Aβ 1−42 @MNP, wherein the peaks at 672, 1343, and 1572 cm −1 were attributed to the C−N, C−H, and N−H bonds, demonstrating that Aβ 1−42 @MNP had been coupled to the surface of the magnetic nanoparticles. 39 Figure 1C shows the hysteresis loops of PEI@MNP and Aβ 1−42 @MNP at room temperature. The saturation magnetization (Ms) values of Aβ 1−42 @MNP and PEI@MNP were 47.0 and 41.5 emu g −1 , respectively.…”

Rapid Determination of Ethyl Carbamate in Chinese Liquor via a Direct Injection Mass Spectrometry with Time-Resolved Flash-Thermal-Vaporization and Acetone-Assisted High-Pressure Photoionization Strategy

“…EC in Yingbin liquor was deducted as the background in the subsequent quantitative analysis. The different concentrations of ethanol solution (10,20,30,40,60,70, and 80% v/v) were prepared with ethanol and purified water. The standard stock solutions of EC (8.94 mg/L), d 5 -EC (8.94 mg/L), and EA (8944.5 mg/L) were prepared in 50% ethanol (vol ethanol /vol water = 1:1, ρ = 0.8945 g/ mL).…”

“…Surface-enhanced Raman scattering (SERS) was reported as a rapid and sensitive approach for qualitative and quantitative analysis of EC. 19,20 However, application of SERS to samples with a complex matrix, such as Chinese liquor, still needs further examination and optimization. 21 Direct injection mass spectrometry (DIMS) based on soft ionization methods is recognized as a versatile and powerful analytical technique for rapid qualitative and quantitative analysis of complex mixtures.…”

Fluorescent sensor based on quantum dots and nano‐porphyrin for highly sensitive and specific determination of ethyl carbamate in fermented food

“…A wide variety of analytical methods, including gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), 7,8 High-performance liquid chromatography (HPLC), 9 Fouriertransform infrared (FTIR) spectroscopy, 10 Raman spectrometry, 11 ratiometric fluorescence enzyme-linked immune sorbent assay (RF-ELISA), 12 and other enzymatic assays, 13 have been established for the detection of EC with high specificity and sensitivity. But the methods of GC-MS/MS, HPLC require expensive equipment and complex operational procedures, high technical requirements, and long detection time, FTIR spectroscopy and Raman spectrometry have poor specificity, and ELISA is usually expensive and complicated.…”