Studying the interaction between CdTe quantum dots and Nile blue by absorption, fluorescence and resonance Rayleigh scattering spectra.

Thioglycolic acid (TGA) capped CdTe quantum dots (QDs) with the diameter of 2-3nm were synthesized. The interaction between CdTe QDs and Nile blue (NB) was investigated by ultraviolet-visible (UV-vis) absorption, resonance Rayleigh scattering (RRS) and fluorescence spectroscopy. UV-vis absorption spectrum of CdTe QDs and NB obviously changed, showing that CdTe QDs could associate with NB to form a new complex. At pH 6.8, NB effectively quenched the fluorescence of CdTe QDs. It was proved that the fluorescence quenching of CdTe QDs by NB was mainly result of the formation of CdTe QDs-NB complex, electrostatic attraction and hydrophobic forces played a major role in stabilizing the complex. The binding molar ratio of CdTe QDs and NB was 5:1 by a mole-ratio method. The interaction between CdTe QDs and NB lead to the remarkable enhancement of RRS and the enchantments were in proportional to the concentration of NB in a certain range. The mechanism of the interaction between CdTe QDs and NB, reasons for the enhancement of RRS intensity were also discussed. The obtained results suggested the more satisfactory mechanism for the interaction between CdTe QDs and NB.

Resonance Rayleigh scattering spectral method for the determination of raloxifene using gold nanoparticle as a probe.

When gold nanoparticles were being prepared by sodium citrate reduction method, citrate anions self-assembled on the surface of gold nanoparticles to form supermolecular complex anions with negative charges, and protonated raloxifene (Ralo) was positively charged and could bind with the complex anions to form larger aggregates through electrostatic force and hydrophobic effects, which could result in the remarkable enhancement of the resonance Rayleigh scattering intensity (RRS), and the appearance of new RRS spectra. At the same time, the second-order scattering (SOS) and frequency-doubling scattering (FDS) intensities were also enhanced. The maximum wavelengths were located near 370 nm for RRS, 520 nm for SOS, and 350 nm for FDS, respectively. Among them, the RRS method had the highest sensitivity and the detection limit was 5.60 ng mL(-1) for Ralo, and its linear range was 0.05-2.37 microg mL(-1). A new RRS method for the determination of trace Ralo using gold nanoparticles probe was developed. The optimum conditions of the reaction and influencing factors were investigated. In addition, the reaction mechanism and the reasons for the enhancement of RRS were discussed.

[Classification of Panax quinquefolium L. and Panax ginseng C. A. Mey. based on FTIR analysis with SVM].

The support vector machine (SVM) is a new learning technique based on the statistical learning theory. In the present paper, forty Panax quinquefolium L. samples were used as experimental materials. The classification models were established using Fourier transform infrared spectra(FTIR)-SVM training method with the intention of identifying whether the Panax quinquefolium L. samples are genuine or they are just Panax ginseng C. A. Mey. samples. The thirty samples in training set were identified by the classifying models with an accurate rate of 100%, while the ten estimate samples had an accurate rate of 90%. The research result shows the feasibility of establishing the models with FTIR-SVM method to identify Panax quinquefolium L. samples and Panax ginseng C. A. Mey.

A study on the sizes and concentrations of gold nanoparticles by spectra of absorption, resonance Rayleigh scattering and resonance non-linear scattering.

Liquid phase gold nanoparticles with different diameters and colors can be prepared using sodium citrate reduction method by controlling the amounts of sodium citrate. The mean diameters of gold nanoparticles are measured by transmission electron microscope (TEM). Gold nanoparticles with different sizes have specific absorption spectra. When the diameters of nanoparticles is between 12 and 41 nm, the maximum absorption peaks locate at 520-530 nm and there are red shifts gradually with the increase of diameters of gold nanoparticles. And when the size of gold nanoparticle is constant, the absorbance is proportional to the concentration of gold. Obvious resonance Rayleigh scattering (RRS) and the resonance non-linear scattering such as second-order scattering (SOS) and frequency-doubling scattering (FDS) appear at the same time as well, and the maximum scattering peaks are located at 286 nm (RRS), 480 nm (SOS) and 310 nm (FDS), respectively. When the concentration of gold is constant, absorbance and the intensities of RRS, SOS and FDS (I(RRS), I(SOS) and I(FDS)) have linear relationships with the diameters of gold nanoparticles. When the diameter of gold nanoparticle is constant, the absorbance and I(RRS), I(SOS), I(FDS) are directly proportional to the concentrations of gold nanoparticles. Therefore, it is very useful for studying the liquid phase gold nanoparticles by investigating the absorption, RRS, SOS and FDS spectra.

[Photochemical preparation of Au nanoparticles with polyethyelene glycol and its resonance scattering spectral study].

The nano-photochemical reaction of polyethyelene glycol (PEG)-Au3+ was studied by resonance scattering and absorption spectrophotometry, and transmission electron microscopy. Influence of various factors on the preparation of gold nanoparticles was considered. There is a correlation between the molecular mass of PEG and the size of gold nanoparticles. A new photochemical method was proposed for the preparation of gold nanoparticles in size of 6-60 nm, using different molecular mass of PEG. The cause of obtaining gold nanoparticle with different size is the different space effect and hydrophobic property of PEG. A reasonable nano-reaction mechanism was developed.