[NIR-SERS Spectra Detection of Cytidine on Nano-Silver Films].

The polyvinyl alcohol (PVA) protected silver glass-like nanostructure (PVA-Ag-GNS) with high surface-enhanced Raman scattering (SERS) activity was prepared and employed to detect the near-infrared surface enhanced Raman scattering (NIR-SERS) spectra of cytidine aqueous solution (10(-2)-10(-8) mol x L(-1)). In the work, the near-infrared laser beam (785 nm) was used as the excitation light source. The experiment results show that high-quality NIR-SERS spectra were obtained in the ranges of 300 to 2 000 cm(-1) and the detection limit of cytidine aqueous solution was down to 10(-7) mol x L(-1). Meanwhile, the PVA-Ag-GNS shows a high enhancement factor (EF) of -10(8). In order to test the optical reproducibility of PVA-Ag-GNS, ten samples of cytidine aqueous solution (10(-2)-10(-5) mol x L(-1)) had been dropped onto the surface of PVA-Ag-GNS respectively. Meanwhile, these samples were measured by the portable Raman spectrometer. As a result, the PVA-Ag-GNS demonstrated good optical reproducibility in the detection of cytidine aqueous solution. In addition, to explain the reason of enhancement effect, the ultraviolet-visible (UV-Vis) extinction spectrum and scanning electron microscope (SEM) of cytidine molecules adsorbed on the surface of PVA-Ag-GNS were measured. There is plasmon resonance band at 800 nm in the UV-Vis extinction Spectrum of the compound system. Therefore, when the near-infrared laser beam (785 nm) was used as excitation light source, the compound system may produce strongly surface plasmon resonance (SPR). According to the SEM of PVA-Ag-GNS, there are much interstitial between the silver nanoparticles. So NIR-SERS is mainly attributed to electromagnetic (EM) fields associated with strong surface plasmon resonance. At last, the geometry optimization and pre-Raman spectrum of cytidine for the ground states were performed with DFT, B3LYP functional and the 6-311G basis set, and the near-infrared laser with wavelength of 785 nm was employed in the pre-Raman spectrum calculation process. The calculation results without imaginary frequency and the results match pretty well with the experimental Raman spectrum. At the same time, the assignations of Raman bands and adsorption behaviors of cytidine molecules on the surface of PVA-Ag-GNS are also discussed. According to our experiment and calculations, cytidine molecules mainly adsorbed on silver nanoparticles via the ribose moiety and amino group may get close to the local electromagnetic field.

[In Situ Research on Ginger Oil Cell with Raman].

This article presents a novel and original approach to analyze the main components of the essential oils in ginger oil cell by means of Raman spectroscopy. Fresh ginger sample was prepareed with free-hand section. Under the DXR Laser confocal micro Raman spectrometer, the oil cell has 20 objective lens. As to the ginger oil cell, the Raman spectrum, all together 21 spectroscopic bands, was obtained. It has been found that the obtained Raman spectrums at different oil cells are very similar. The Raman spectrum of the commercial essential oils of ginger, together 37 spectroscopic bands, was obtained. It has been found that the 19 presented spectroscopic bands of ginger oil cell correlate very well with those obtained by the commercial essential oils. Density Functional Theory (DFT) of zingiberene calculations were performed in order to interpret the spectra of the essential oils of the ginger oil cell and essential oils of ginger. There are 31 spectroscopic bands of the essential oils of ginger, and 19 spectroscopic bands of ginger oil cell correlate very well with calculations. All these investigations are helpful tools to generate a fast and easy method to control the quality of the essential oils with Raman spectroscopic techniques in combination with DFT calculations.

[Research on volatiles of rakkyo (Allium Chinense G. Don) and Chinese chive (Allium Tuberosum Rottl. ex Sprengel) based on headspace and the molecular recognition of SERS].

The head space and the molecular recognition of surface enhanced Raman scattering (SERS) were used to research volatiles of rakkyo and Chinese chive. Their volatiles SERS spectra were obtained using nano-silver colloid as the substrate. Then, volatiles SERS spectra of rakkyo and Chinese Chive were compared respectively with the volatiles SERS spectra of liquid allyl methyl sulfide, 1-propanethiol, diallyl disulfide and all possible pairings of the three compounds. The results showed that the repeatability of volatiles SERS spectra of rakkyo and Chinese Chive were all good. The volatiles SERS spectrum of rakkyo was basically consistent with the volatiles SERS spectrum of the mixture of liquid allyl methyl sulfide and 1-propanethiol. The volatiles SERS spectrum of rakkyo included both characteristic peaks at 626 and 674 cm(-1) in volatiles SERS spectrum of allyl methyl sulfide and characteristic peaks at 702, 893, 1024,1085, 1215 and 1320 cm(-1) in volatiles SERS spectrum of 1-Propanethiol. The volatiles SERS spectrum of Chinese chive was basically consistent with the volatiles SERS spectrum of the mixture of liquid allyl methyl sulfide and diallyl disulfide. The volatiles SERS spectrum of Chinese chive included both characteristic peak at 674 cm(-1) in volatiles SERS spectrum of allyl methyl sulfide and characteristic peaks at 407, 577, 716, 1189, 1291 and 1401 cm(-1) in volatiles SERS spectrum of diallyl disulfide. These illustrated that volatiles of rakkyo contained allyl methyl sulfide and 1-Propanethiol and volatiles of Chinese chive contained allyl methyl sulfide and diallyl disulfide. The volatiles of rakkyo and Chinese chive were different, but they all contained allyl methyl sulfide. All of the above have revealed that the headspace combined with molecular recognition of SERS can be directly used to study volatiles of rakkyo and Chinese chive. The technology under room temperature, can guarantee the volatiles obtained were the primitive constituents in plant volatiles. By comparison with the standard sample, the constituents in plant volatiles can be determined.

[Discrimination of bamboo using FTIR spectroscopy and statistical analysis].

Fourier transform infrared (FTIR) spectroscopy combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to identify and classify bamboo leaves. FTIR spectra of fifty-four bamboo leaf samples belonging to six species were obtained. The results showed that the infrared spectra of bamboo leaves were similar, and mainly composed of the bands of polysaccharides, protein and lipids. The original spectra exhibit minor differences in the region of 1800-700cm-1. The second derivative spectra show apparent differences in the same region. Principal component analysis and hierarchical cluster analysis were performed on the second derivative infrared spectra in the range from 1800 to 700 cm-1. The leaf samples were separated into 6 groups with accuracy of 98% with the first three principal components, and with 100% accuracy according to the third and fourth principal components. Hierarchical cluster analysis can correctly cluster the bamboo leaf samples. It is proved that Fourier transform infrared spectroscopy combined with PCA and HCA could be used to discriminate bamboo at species level with only a tiny leaf sample.