The investigation of the interaction between ribavirin and bovine serum albumin by spectroscopic methods.

The interaction between ribavirin (RIB) with bovine serum albumin (BSA) has been investigated by fluorescence quenching technique in combination with UV-vis absorption and circular dichroism (CD) spectroscopies under the simulative physiological conditions. The quenching of BSA fluorescence by RIB was found to be a result of the formation of RIB-BSA complex. The binding constants and the number of binding sites were calculated at three different temperatures. The values of thermodynamic parameters ∆H, ∆S, ∆G at different temperatures indicate that hydrophobic and hydrogen bonds played important roles for RIB-BSA association. The binding distance r was obtained according to the theory of Förster's non-radiation energy transfer. The displacement experiments was performed for identifying the location of the binding site of RIB on BSA. The effects of common ions on the binding constant of RIB and BSA were also examined. Finally, the conformational changes of BSA in the presence of RIB were also analyzed by CD spectra and Synchronous fluorescence spectra.

[Comparison of ICP-MS and two other analytical methods for determination of selenium content in Cordyceps militaris].

Samples were digested by microwave digestion. The selenium content in selenium enriched Cordyceps militaris was determined by ICP-MS method, HPLC/fluorometric method, and 3,3-diaminobenzidine method separately. And the detection conditions, the lowest detection limit and the relative standard deviation (RSD) of the three determination methods were compared. The detection conditions of the three methods for the detection of selenium content in selenium enriched Cordyceps militaris were established. It was showed that the lowest detection limit of ICP-MS method, HPLC/fluorometric method, and 3,3-diaminobenzidine method was 0.260 7, 0.182 1 and 10.485 9 microg x L(-1) respectively, and this means that the lowest detection limit of ICP-MS method was the lowest and that of 3,3-diaminobenzidine method was the highest. For the same sample the relative standard deviation (RSD) of ICP-MS method was the lowest and the RSD of 3,3-diaminobenzidine method was the highest. It was recommended that selenium content is determined by ICP-MS and HPLC/fluorometric method when the selenium in the sample is very low and by 3,3-diaminobenzidine method when the content is rather high.

[Study of autofluorescence spectra of protoporphyrin IX in human serum].

The fluorescence spectra of protoporphyrin IX (PPIX) solutions and human serum samples were measured and analyzed under physiological conditions. The experimental results showed that the fluorescence of PPIX in human serum was mainly derived from PPIX-serum albumin complex. Moreover, the effects of serum albumin and PPIX on the PPIX emission fluorescence were also investigated. Compared with pure PPIX solution, not only a red-shift of PPIX fluorescence peak was found for PPIX+albumin solution, but also albumin had a fluorescence enhancement effect on protoporphyrin IX. For the mixture of PPIX+albumin, with the increase of PPIX the wavelength of the PPIX emission peak will increased a little when its concentration was less than 0.8 x 10(-5) mol x L(-1), but was nearly invariable when its concentration was more than 0.8 x 10(-5) mol x L(-1).

[Preparation of nanometer TiO2 doped with upconversion luminescence agent and investigation on degradation of ethyl violet using visible light].

A novel upconversion luminescence agent 40CdF2 x 60BaF2 x 1.6Er2O3 was synthesized and the fluorescent spectrum was determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks whose wavelengths are all below 387nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nanometer TiO2 powder by ultrasonic dispersion and the doped nanometer TiO2 photocatalyst utilizing visible light was prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was checked through the photocatalytic degradation of ethyl violet dye as a model compound under the visible light irradiation emitted by three basic color lamp. Otherwise, in order to compare the photocatalytic activities the same experiment was carried out for undoped photocatalytic TiO2 powder. The degradation ratio of ethyl violet dye in the presence of doped nanometer TiO2 powder reached 99.68% under visible light irradiation at 12.0 h which was obviously higher than the corresponding degradation ratio in the presence of undoped nanometer TiO2 powder, which indicate that the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights which are absorbed by nanometer TiO2 particles and produce the electron-cavity pairs.

Degradation of dyestuff wastewater using visible light in the presence of a novel nano TiO2 catalyst doped with upconversion luminescence agent.

A new upconversion luminescence agent, 40CdF2 x 60BaF2 x 0.8Er2O3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.