Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate.

Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br(-) and I(-)), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd(2+) at 10(-8) M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface.

Approach for determination of ATP:ADP molar ratio in mixed solution by surface-enhanced Raman scattering.

The ATP:ADP molar ratio is an important physiological factor. However, in previous literatures, ATP and ADP could not be distinguished by Raman spectroscopy due to the high similarity of molecular structure. To challenge this problem, also considering that the γ phosphate group may interact with adenine group and cause a different variation of the Raman spectrum than that of ADP, a highly sensitive, low-cost, environment protecting, flexible and super-hydrophobic Au nanoparticles/cicada wing (Au/CW) substrate with three-dimension structure was fabricated and employed as an active surface-enhanced Raman scattering (SERS) substrate to detect the ATP:ADP molar ratios. The concentration as low as 10(-8)M for ATP and ADP was analyzed to determine the limit of detection. This SERS study on various ATP:ADP molar ratios demonstrates that ATP:ADP could be distinguished and the quantitative determination of ATP content was achieved. Moreover, a principle was speculated based on the molecular structures of ATP and ADP of the Raman peaks centered at ~685 and ~731cm(-1) to explain the linear relationship between the area ratio and the molar ratio. A new method has been developed for quantitative determination of ATP:ADP molar ratio based on Au/CW substrate by the SERS method.

[Determination of benzyl glucosinolate in Lepidium meyenii from different regions by HPLC].

The content of benzyl isothiocyanate (BITC) which as the enzymatic hydrolysis product of benzyl glucosinolate through thioglucosidase was determined by HPLC. The content of benzyl isothiocyanate (BITC) which as the enzymatic hydrolysis product of benzyl glucosinolate through thioglucosidase was determined by HPLC. The chromatography condition was as follows: Kaseisorb LC ODS 2000 (4.6 mm x 150 mm, 5 min) column with the mobile phase of acetonitrile(A)-water( B) under gradient elution (0-5 min, 3%-8% A; 5-9 min, 8%-48% A; 9-23 min, 48%-62% A; 23-28 min, 62%-99% A); the flow rate was 1.0 mL x min(-1) with 10 microL injection volume; detection wavelength was 246 nm and temperature of column was 40 degrees C. The content of benzyl glucosinolate was in the range of 10.76-17.91 g x L(-1). The method is simple, accurate and good reproducibility which can be used for the determination of benzyl glucosinolate in Lepidium meyenii, effectively.

Si/ZnO nanocomb arrays decorated with Ag nanoparticles for highly efficient surface-enhanced Raman scattering.

High-density ZnO nanocombs were first grown on a nanoporous silicon pillar array, and pre-prepared 3D Si/ZnO/Ag nanocomb arrays were employed as substrates for surface-enhanced Raman scattering (SERS). The finite-difference time-domain simulation result shows that two kinds of inter-Ag-NP nanogaps in the geometry create a large number of SERS "hot spots," which contributes to the detection limits for rhodamine-6G as low as 10⁻¹² M and the Raman enhancement factor as large as 109. The linear dependence between the Raman peak intensities and the concentrations of thiram provides a new calibration method for rapid and quantitative detection of trace organic molecules.

Two new flavonols from Cudrania cochinchinensis.

Two new flavonols, 6-p-hydroxybenzyl kaempferol (1) and 6-p-hydroxybenzyl quercetin (2), together with six known compounds were isolated from the roots of Cudrania cochinchinensis and their structures elucidated on the basis of spectroscopic methods. Their antioxidant capacities were evaluated by 1,1-diphenyl-2-picryl-hydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging assays. The results suggested that compounds 2, 4, and 7 showed significant radical-scavenging activities.

[Effect of the chelator Zn-DTPA on the excretion of lead in lead intoxication mice detected with ICP-MS].

To study the lead excretion effect of the chelator Zn-DTPA on the lead intoxication mice, inductively coupled plasma mass spectrometry (ICP-MS) was applied to detect the lead content of biological samples. The acute lead intoxication mice model was established by injecting lead acetate intraperitoneally with the dose of 1 mg. Zn-DTPA was administered intraperitoneally to mice once daily for five consecutive days 4 h after intoxication. Control group, model group, combination of Zn-DTPA and Ca-DTPA group were evaluated at the same time. The urine was collected every day. The mice were sacrificed in batches in the 2rd, 4th, 6th day. Biological samples including urine, whole blood, femur and brain were prepared and nitrated. Lead concentration was detected by ICP-MS. The result showed that Zn-DTPA could increase lead content in urine markedly and reduce lead content in blood, femur and brain.