[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.

[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.

[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.

[Study of volatile organic compounds of fresh allium species using headspace combined with surface-enhanced Raman scattering].

In order to identify volatile organic compounds of fresh plants at room temperature and avoid sample pretreatment and extractions which can be labor intensive, garlic, Chinese chives and scallion were chopped into pieces. Then some of them were placed in the headspace vial and sealed. The gases were drawn from the vial with a syringe and were injected very slowly into Ag colloids for test using R-3000 portable Raman spectrometer. The spectra of volatile organic compounds of allium species, fresh garlic, Chinese chive and shallot plants were successfully.recorded for the first time. For garlic high intensity bands are present at 307, 399, 569, 711, 1,182, 1,287, 1,397 and 1,622 cm(-1). For Chinese chives the high intensity band is present at 672 cm(-1). Low intensity bands are present at 274, 412, 575, 1,185, 1,289, 1,396, 1,618 cm(-1). For shallot high intensity bands are present at 693 cm(-1). Lower intensity bands are present at 372, 888, 1,023 cm(-1). Low intensity bands are present at 1,088, 1,211 and 1,322 cm(-1). The SERS of diallyl disulfide, allyl methyl sulfide and 1-propanethiol in liquid state and gas state were also obtained. The main volatile organic compound of fresh garlic, Chinese chive and shallot are diallyl disulfide, allyl methyl sulfide and 1-propanethiol respectively, and the volatile organic compound of fresh onion, scallion, shallot and chive are all 1-propanethiol. The presented results illustrate that combining headspace and SERS is a powerful tool for volatile organic compound analysis in fresh plants. The volatile organic compound can be detected in fresh plant samples directly and quickly without extraction.

[Elementary SERS spectroscopy studies of three kinds of pathogens in Ag colloids prepared by microwave method].

The normal Raman (NR) and surface enhanced Raman spectroscopy (SERS) for Alternaria alternate, Colletotrichum musae, and fusarium suspensions were measured by a portable Raman spectrometer (785 nm). The result indicates that the silver colloid prepared by microwave method shows high enhancement of Raman scattering for the three kinds of pathogens. Comparing SERS spectrums of the three kinds of pathogens, there are some similarities. In these SERS spectrums, the peaks in the range of 500-1 000 cm(-1) are very weak. Additionally, the peaks in the range of 1 000-1 600 cm(-1) are strong. Meanwhile, the peak at 481 cm(-1) is the strongest. Although these spectrums are similar, there are some differences such as the distribution and shape of peaks. Therefore, the three kinds of pathogens can be discriminated quickly.

[Preparation and SERS activity studies on substrate of nano-silver film with broad plasma absorption band].

A highly reproducible and broad plasma absorption band nano-silver film was prepared by electrostatic self-assembly technology. The size of nano-silver particles on the surface of silver film, in the scanning electron microscopy (SEM) micrograph, is in a wide distribution from 18 to 200 nm. At the same time, the ultraviolet-visible spectrophotometer was employed to detect the nano-silver film. There is a broad plasma absorption band in the UV-Vis spectrum. To test the SERS activity of the nano-silver film, crystal violet and serum of healthy person were used as probe molecules and the high quality SERS spectra were obtained.

[SERS spectroscopy study of three pathogenic bacteria].

The SERS spectra of staphylococcus aureus, proteus, and Escherichia coli was obtained on colloidal Ag nanoparticles prepared by the microwave method with the portable Raman spectrometer. Staphylococcus aureus have obvious Raman vibrating peak at 725, 1 330 and 1 450 cm(-1), proteus have obvious Raman vibrating peaks at 650,725,950, 1 325 and 1 463 cm(-1), while E. coli have obvious Raman vibrating peaks at 650, 950, 1 125, 1 242,1 320 and 1 457 cm(-1). Each peak was assigned preliminarily. Not only the position of Raman vibration peaks but also the intensity of the three bacteria is obviously different, so SERS can be used for identification and distinction of E. coli, staphylococcus aureus and proteus.

[Analysis of surface enhanced Raman scattering spectra of oxyhemoglobin for liver cancer with combined multivariate statistics].

Investigation of surface-enhanced Raman spectra of oxyhemoglobin for 30 liver cancers and 30 normal persons based on the silver nanofilm was reported. Principal components analysis (PCA) and independent variable T test were employed to develop effective diagnostic algorithms for distinguishing liver cancer form normal. Discriminant analysis was used to evaluate the diagnostic efficiency and the result indicates that SERS spectra of the oxyhemoglobin are obviously different between normal persons and liver cancers. PCA and independent variable T test were employed to get a three-dimensional scatter plot of PC scores for the healthy and cancer groups, and it can be learned that they are distributed in separate areas. By using the method of discriminate analysis, it was fount that the diagnostic algorithm separates the two groups with sensitivity of 96.7% and diagnostic specificity of 90%, the overall diagnostic accuracy was 93.3%. By analyzing the assignations of the SERS bands, it was found that the content of asparagine, tyrosine and phenylalanine in the hemoglobin are significantly lower than healthy people. The results from this exploratory study demonstrate that SERS detection of oxyhemoglobin for liver cancers based on the method of PCA combined with independent variable T test is expected to develop into a new type of liver cancer diagnostic tool.

[SERS spectra of Xanthomonas oryzae pv. Oryzae (Xoo) on nano silver film prepared by electrolysis method].

The nano silver film was prepared by electrolysis method using silver nitrate and polyvinyl alcohol (PVA) in deionized water as the electrolyte, with four glass slides put in the electrolyte and two silver rods dipped into the electrolyte as the anode and cathode. A direct current was applied to the rods, then the four glass slides stayed in the silver colloids. Thus the authors got the nano silver film. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to detect the silver particles in the silver colloids and on the nano silver film. From the SEM we can see that the silver particles on the film formed different layers. In one layer, the distance between two particles was about 100 nm. The samples of Xanthomonas oryzae pv. Oryzae (Xoo) were 7 different kinds of bacterial blight, namely 1-YN1, 2-YN7, 3-YN11, 4-GD414, 5-SCYC6, 6-HEN11 and 7-FWJ. Because the silver particles in the colloids were aggregated on the film, there was large electromagnetic potentiation. So the SERS spectra of Xoo were perfect. The authors used the area analytical method to distinguish the different kinds of Xoo. The silver film prepared by electrolysis was cheap and active, the preparation time of the samples was short, and any normal chemistry lab can make it, which can find excellent application to detecting the Xoo in agriculture. On the other hand, this film is active on biomolecules and bioorganism, which may be a new kind of SERS fundus to explain the creation of the SERS. Further study was under way.

[Investigation of typical melamine urinary stones using infrared spectra].

A typical melamine kidney stone confirmed by some medicine expert was collected from the first people's hospital of Yunnan. The kidney stone was adequately determined by PE corporation spectra 100(with resolution of 1 cm(-1)). The stone samples for FTIR analysis were prepared using the KBr pellet technique, where 2 mg of the pretreated stone powder was mixed with 200 mg of analytical grade KBr using an agate pestle and mortar. The digital spectrum was then scanned in the mid-infrared region from 4 000 to 400 cm(-1) at room temperature. The appearing bands between 4 000 and 2 000 cm(-1) were 3 487, 3 325, 3 162 and 2 788 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 694, 1 555, 1 383, 1 340, 1 189 and 1 122 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 782, 748, 709, 624, 585, 565 and 476 cm(-1). It was found that the main constituent of calculi showed few comparability with cat kidney stone, which was from cats that died after consuming the contaminated food, and confirmed that these deposits were primarily composed of melamine and cyanuric acid compared to the IR spectra of calculi in literature. It was also found that the main constituent of calculi showed few comparability with popular kidney stone by comparison with the IR spectra of calculi in literature. The spectrum of calculi was 50% respectively similar with melamine and uric acid as compared with the IR spectrum. It was found that the main constituent of calculi was melamine itself and uric acid as compared with the IR spectra of calculi and melamine: (1 : 1), because the spectrum of calculi was 83. 3% similar to melamine and uric acid (1 : 1). The appearing bands of melamine and uric acid (1 : 1) between 4 000 and 2 000 cm(-1) were 3 469, 3 419, 3 333, 3 132, 3 026, 2 827 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 696, 1 656, 1 555, 1 489, 1 439, 1 350, 1 311, 1 198, 1 124 and 1 028 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 878, 814, 784, 745, 708, 619, 577 and 475 cm(-1).

[AgBr colloids prepared by electrolysis and their SERS activity research].

Ivory-white AgBr colloids were prepared by means of electrolysis. Two silver rods 1.0 cm in diameter and 10.0 cm long were respectively used as the negative and positive electrodes, the aqueous solution of hexadecyl trimethyl ammonium bromide was used as the electrolyte, and a 7 V direct current was applied on the silver rods for three hours. The obtained AgBr colloids were characterized by UV-Vis spectroscopy, transmission electron microscopy, and SERS using a 514. 5 nm laser line on Renishaw 2000 Raman spectrometer. These particles are about nanometer size and their shapes are as spherical or elliptic, with a slight degree of particle aggregation. The UV-Vis spectra exhibit a large plasmon resonance band at about 292.5 nm, similar to that reported in the literature. The AgBr colloids were very stable at room temperature for months. In order to test if these AgBr colloids can be used for SERS research, methyl orange, Sudan red and pyridine were used. It was found that AgBr colloids have SERS activity to these three molicules. For methyl orange, the intense Raman peaks are at 1 123, 1 146, 1 392, 1 448 and 1 594 cm(-1); for Sudan red, the intense Raman peaks are at 1 141, 1 179, 1 433 and 1 590 cm(-1); and for pyridine, the intense Raman peaks are at 1 003, 1 034 and 1 121 cm(-1). It is noticeable that SERS of methyl orange was observed on AgBr colloids, but not on the gray and yellow silver colloids prepared by traditional means. The possible reason was explained. One major advantage of this means is the absence of the spectral interference such as citrate, BH4- arising from reaction products of the colloids formation process. On AgBr colloids, one can get some molecular SERS impossible to get on the gray and yellow silver colloids.

[Comparative study on SERS and stability of negative silver colloids].

Negatively charged colloidal nano-silver particles were prepared by the colloidal chemical method. A 1.7% solution of silver nitrate (2 mL) was diluted with deionized water to 100 mL. A 1% solution of tannic acid (1 mL) was added dropwise to the solution stirring, then a 1% solution of potassium carbonate anhydrous (3-4 drops) was added to the mixed solution. Finally, a red-brown silver sol was obtained. It was testified that the silver sol is a negatively charged colloid by experiment of electrophoresis. The negative silver colloids (for short, old NCS) were kept on at the room temperature two year ago in order to test its SERS and stability. The sizes of particles were determined by Hitachi H-800 transmission electron microscope. Absorption spectroscopy and SERS were used to determine the main properties. Absorption spectra were obtained with UV-2401PC. Raman spectra were recorded with RENISHAW MIK 2000 Raman micro-spectroscopy. The 514.5 nm line of an argon ion laser with about 3 mw was used. Compared with the newly prepared negative silver colloids (for short, new NCS). It was found that the mean diameter of the old NCS was larger than the new NCS; old NCS had absorption maximum at 431 nm but new NCS at 418 nm, the absorbance spectrum of old NCS had a 12 nm red shift, and the red shift rate is about 0.5 nm/month; Both strong SERS spectra were observed when cationic molecules of fuchsine basic and neutral molecules of alcidine orange adsorbed on old NCS and new NCS. For cationic molecules of methylene blue, the SERS is stronger on new NCS than old NCS; but no SERS was observed for the anionic molecule of benzoic acid both on new NCS and on old NCS.

[Nano-silver colloids prepared by electrolysis and research on its SERS activity].

Three kinds of nano-silver colloids have been prepared by electrolysis of silver rod using sodium citrate solution and AgNO3 mixed with polyvinyl alcohol solution as electrolyte and applying 7 V direct current for one hour. Nano-silver colloids have been investigated by means of TEM, absorption spectrum, electrophoresis experiment and SERS. The particle size ranges roughly from 20 nm to 25 nm (spheroid) for sample 1, from 20 nm to 35 nm (spheroid) for sample 2, and from 30 to 80 (many-sided) for sample 3, featuring absorption maximum at 404, 421 and 434 nm, respectively. The surface charge of these three kinds of colloidal silver particles is positive. In order to test if these nano-silver colloids can be used for SERS research, the cationic molecular fuchsine basic, methylene blue, anionic molecular benzoic acid, methyl orange, neutral molecular alcidine orange, and Sudan red were used. It was found that these nano-silver colloids have strong SERS activity. Furthermore, the nano-silver colloids that used AgNO3 mixed with polyvinyl alcohol solution as electrolyte has the strongest SERS activity among all the tested molecules. The SERS of methyl orange has been obtained on the nano-silver colloids, which has not been obtaind on the colloids prepared by electrolysis of silver rod using sodium citrate solution and on the gray and yellow silver colloids prepared by traditional means. The possible reason has been explained. One major advantage of this method (using AgNO3 mixed with polyvinyl alcohol solution as electrolyte) is the absence of the spectral interference.

[SERS of positive silver colloids with addition of aggregating agent].

A very strong surface-enhanced Raman scattering (SERS) spectrum was obtained when adding some aggregating agent such as HNO3 and NaNO3 in positive silver colloid reduced by citrate using 633 nm radiation. In aid of characterizing the SERS of this process, SERS from positive silver colloid with the addition of H2SO3, HCl, and NH3 recorded. It was found that the SERS come from the citrate when adding HNO3, NaNO3 and H2 SO3, from NH3 and citrate when adding NH3, and only from Ag-Cl when adding HCl through comparing the spectra. Furthermore, the surface layer of positive silver colloid particles could be Ag+ , and the diffusion layer could be citrate.

[The SERS of glycine anhydride on positive silver colloids].

The Raman spectrum and SERS of glycine anhydride in acidic and basic media on positive silver colloids were recorded. Calculations of the vibration frequencies were performed for glycine anhydride by B3LYP at 6-31g(d) level. The assignment of Raman spectrum and SERS of glycine anhydride in acidic media were obtained with the help of calculation. It was found that the glycine anhydride is physically adsorbed on the surface of silver. The SERS of glycine anhydride is very different in acidic media from that in basic media. This seems to mean that the geometry of glycine anhydride on positive silver colloid in basic media has changed.