The Fluorescence Study On The Reciprocities Between The Quinolones Antibiotics And Biological Molecules

In recent years, the problem caused by the antibiotics abuse has been more and more serious. The influences of the vestigtal antibiotics in environment on organism have become the important aspect to research. Specially, the study from molecule view is few.The three kinds of molecular emission spectroscopy, the synchronous fluorescence, the fluorescence queenching emission spectroscopy and the fluorescence resonance energy transfer, were used to research the reciprocity mechanism between the vestigtal antibiotics in environment and the digestive ferments which play the important part in the digestive system. The theory data on the combination of the Quinolones antibiotics and biological molecules was gotten, which afforded the theory basis for the next research which would be on the influences on the organism from antibiotics and the combination of new type environment-friendly antibiotics. The character of biological molecules to combine with the molecule emitting probe was also used to build a new determination, that made some donation for the research from microscopic view in environment.What we used in this paper was the fluorescence quenching theory, FRET theory in molecule fluorescence spectroscopy and the Enoxacin, Ofloxacin and Levofloxacin Lactate as the represent of the Quinolones antibiotics. The reciprocity between them and digestive ferments was studied under the lab conditions. The results suggested that when maintaining the consistent densities of digestive ferments, the intensities of their endogensis fluorescence fell regularly as the increase of the Quinolones antibiotics'consistencies, which the densities of OFLX and LOFL increased regularly while the one of ENX maintained. It was concluded that the Quinolones antibiotics reacted with the Try and Tyr residues and the new rigid molecule formed between the OFLX, the LOFL and the ferments to make the phenomenon of FRET happened. The further research by the fluorescence quenching theory showed that the reciprocities of the Quinolones antibiotics and the ferments belongs to the static quenching, the combining number of locus and the type of the bonding were calculated combined with the FRET and chemical thermodynamics theory.A new FRET system was built by using energy transfer from FITC to Rhodamine 6G. It was found that at the condition ofλex/λem=400nm/530nm and 0.1mol/L Tris(pH=7.0), the effective energy transfer could occur between FITC and Rhodamin 6G. The fluorescence intensity of FITC reduced and Rh6G was strengthen at the same time. But if adding the BSA to this system, the fluorescence intensities of Rh6G reduced. So this system of fluorescence resonance energy transfer was applied to the determination of BSA. The detection limit of this method was 9.5mg/L. The range of determination for nitrite was 10～35mg/L. The recoveries were 96.5%.The method has been applied to the determination of BSA in mixed samples with satisfactory results.Another new FRET system was built also by using energy transfer from Rhodamine 123 to Rhodamine B. It was found that at the condition ofλex/λem=478nm/580nm and 0.1mol/L Tris(pH=7.0), the effective energy transfer could occur between Rh123 and RhB. The fluorescence intensity of Rh123 reduced and RhB was strengthen at the same time. But if adding the BSA to this system, both of their fluorescence intensities reduced. So this system of fluorescence resonance energy transfer was applied to the determination of BSA. The detection limit of this method was 8.6mg/L. The range of determination for nitrite was 8～23mg/L. The recoveries were 92.3%.The method has been applied to the determination of BSA in mixed samples with satisfactory results.The chemical mechanism of the reciprocities between the Quinolones antibiotics and the ferments was studied initially with the fluorescence quenching theory. In this paper the basic research work was done and afforded the theory basis for the new probe to the antibiotics. Meantime we also studied the application of the FRET in the determination of biological organism maintaining their biological characters. The systems built in this paper have the practical application value which are sensitive, well-selecting, convenient, inexpensive. The mechanism of the new methods was also studied.