[Investigation of interaction between riboflavin and riboflavin binding protein by fluorescence spectroscopy].

The interaction between riboflavin and egg white riboflavin binding protein (RBP) was investigated using fluorescence spectroscopy. The binding mode, binding constants, thermodynamic parameters between riboflavin and RBP and energy transfer were studied. The experimental results showed that riboflavin has the ability to quench the intrinsic fluorescence of RBP because of a complex formed, and the quenching mechanism is static quenching. The binding constants were 5.35 x 10(8), 1.54 x 10(8), 0.56 x 10(8) L x mol(-1) at 298, 308 and 318 K, respectively. The thermodynamic parameters were calculated, which suggested hydrogen bonds and Van der Waals played a major role in the interaction. The distance and efficiency of energy transfer between riboflavin and RBP were 0.70 nm and 0.39, respectively, based on the theory of Forster nonradiative energy transfer. Furthermore, the synchronous fluorescence spectroscopy was utilized to investigate the conformational transformation.

[Effect of S-configuration transformation on the microstructure of ovalbumin].

The effect of S-configuration transformation on the microstructure of ovalbumin was studied by CD spectra, XRD spectra, ANS fluorescence probe emission spectra and UV absorption spectra. CD spectra was used to examine the changes in the secondary structure of the ovalbumin during S-ovalbumin information process. When the induction time was prolonged, the mutual transformation between alpha-helix, beta-sheet, beta-turn and the random coil was observed, and the orderliness of the secondary structure was increased with alpha-helix decreasing slightly and beta-sheet increasing correspondingly. XRD spectra analysis showed that the crystal structure content of the ovalbumin increased with prolonging the induction time and the largest data was observed at 72 h, indicating that the orderliness of the secondary structure was increased. The results were similar to CD spectra analysis. The ANS fluorescence probe emission spectra analysis demonstrated that S-configuration transformation induced an increase in surface hydrophobicity with prolonging the induction time, and the largest data was also observed at 72 h. In addition, UV absorption spectra analysis indicated that S-configuration transformation resulted in a decrease in the UV-absorption maximum value with prolonging the induction time, indicating that the aromatic amino acid was buried in the molecular interior. The results indicated that the changes in the microstructure of ovalbumin were relevant to S-configuration transformation.

[A facile colloid aqueous method for synthesis of water soluble ZnSe quantum dots with high fluorescence and stability characterization].

Highly fluorescent and stable ZnSe quantum dots were synthesized by a facile colloid aqueous phase route. It overcame the defects such as instability and low quantum yields of the quantum dots synthesized by early aqueous phase route. Optimum conditions were found. L-glutathione was used as the stabilizer, the molar ratio of L-glutathione, Se2- and Zn2+ is 5 : 1 : 5, the reaction media is pH 10.5, and the proper temperature is between 90 and 100 degrees C. Quantum yields (QYs) could reach to 50.1% without post irradiation in prime synthetical conditions. And the fluorescence intensity of ZnSe QDs almost didn't change after 3 months. Its water-soluble property is also excellent. The properties of ZnSe QDs were characterized by means of ultraviolet visible spectra, fluorescence spectra, and transmission electron microscopy. The synthesized ZnSe QDs emit blue-purple fluorescence (370 nm) when excited at 300 nm. And the excellent photochemical characteristics of the ZnSe QDs will be advantageous in the application in optothermal device manufacture and chemistry biology domain.

In situ electrostatic assembly of CdS nanoparticles onto aligned multiwalled carbon nanotubes in aqueous solution.

A simple method is described for the electrostatic assembly of CdS nanoparticles onto oxidized aligned multiwalled carbon nanotubes (MWCNTs) in aqueous solution. The method is convenient to control and allows the formation of a stable, water-soluble suspension of CdS/aligned-MWCNT heterostructures. The prepared CdS/aligned-MWCNT heterostructures are characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR). The fluorescence and UV absorption spectral properties of the hybrid material demonstrate electron transfer from CdS nanoparticles to aligned-MWCNTs, which implies its potential applications in photovoltaic cells, photocatalysis, and solar energy conversion.

[Synthesis of mixed complexes of lanthanum with 2,2-bipyridyl and 1,10-phenanthroline and study of the interaction of the complexes with DNA].

A mixed complex of La with 2,2-bipyridyl (dpy) and 1,10-phenanthroline(phen) was synthesized. Elemental analysis, IR and TGA of the complex were investigated, thus it was proved that the conformation of it was La(dpy)(phen)Cl3. The interaction of the complex with DNA has been studied also. The spectra showed that the interaction between La(dpy)(phen)Cl3 and DNA experienced intercalation of long-range self-assembly. The study made it clear that the synthesized mixed complex La(dpy)(phen)Cl3 can interact with DNA, and La(dpy)(phen)Cl3 can be used for probing a nucleic acid.