Balofloxacin-rare Earth Complex Fluorescent System And Its Application

The quinolones(pyridone acids)are a family of synthesized antibiotics,which are named because of the quinolone structure in the organic compound.The number of drug varieties has increased greatly since the first quinolones drug,nalidixic acid discovered in 1962.The action mechanism of fluoroquinolone drugs is inhibitting bacterial DNA helix enzyme and(or)topisomeraseâ…£,affecting the normal morphology and function of the bacterial,impeding the normal DNA replication, transit and reorganization,and which enable they have resulting in the rapid germicidal effect.The quinolones which are applied widely in clinic,have many advantages such as broad antibiotical spectrum,good oral absorption,high plasma concentration,less drug-resistant strains,rapid distribution to various organizations and long half-time,and etc.The quinolones have the strcture ofα-ketoacid,which can form complex with rare earth ions in certain conditions.The complex absorbed ultraviolet light energy,emited the characteristic fluorescence of the core ion via inter-system crossing.The fluorescence spectroscopy of rare earth ions is a sharp lines spectrum,with high selectivity.Its luminous intensity will be greatly enhanced when combined with appropriate organic ligands.The research about the fluorescence charactistics and the application of the complex has developed greatly in recent years.There is considerable interest in the study on these complexes because of their potential application for determination of the rare earth elements,or conversely,for determination of the organic ligands,or as fluorescent probes in clinical chemistry, molecular biology,environmental sciences,and etc.In this thesis,the fluorescence characteristics of the BLFX-Eu³⁺and BLFX-Tb³⁺ complex are studied.The fluorescence system is optimized by introducing of surfactant and altering pH conditions.The above fluorescence system is applied to determine the BLFX in pharmaceutical samples and biological samples with satisfactory results.The determination results of this method are compared with that of the HPLC method.And the sensitization mechanism of these systems is also studied by sereral measures.In the first chapter,we summarize the mechanism and progress of fluorescent probe of rare earth ions and the main determination methods of fluoroquinolones.In the second chapter,the BLFX-Eu³⁺fluorescence system is studied in detail,and the BLFX-Eu³⁺-SDBS fluorescence system is set up.It is found that the anionic surfactant SDBS can greatly increase the fluorescence of the system.The excitation and emission wavelengths are determined as 335 nm and 618 nm,respectively.Under the optimum conditions,a linear relationship is obtained between the fluorescence intensity and europium ion concentration in the range of 1.0×10^-8～8.0×10^-7mol/L. The correlation coefficient(r)is equal to 0.9994 and the detection limit of BLFX is 2.0×10^-9mol/L.The method is successfully applied to the determination of balofloxacin in pharmaceutical samples and human urine/serum samples.The comparison between results of this method and that of the HPLC method show that the two methods have no significant difference,and can be replaced by each other. The mechanism of fluorescence system is studied from the following aspects:the formation and the structure of complex,the role of surfactant and action mechanism.In the third chapter,the BLFX-Tb³⁺fluorescence system is studied in detail,and the BLFX-Tb³⁺-SDBS fluorescence system is set up.The complex of BLFX-Tb³⁺can emit intrinsic fluorescence of Tb³⁺.It is found that the anionic surfactant SDBS can greatly increase the fluorescence of the system.The excitation and emission wavelengths are determined as 335 nm and 547 nm,respectively.Under the optimum conditions,a linear relationship is obtained between the fluorescence intensity and europium ion concentration in the range of 8.0×10^-9～5.0×10^-7mol/L.The correlation coefficient(r)is equal to 0.9993 and the detection limit of BLFX is 7.0×10^-11mol/L. The method was successfully applied to the determination of balofloxacin in pharmaceutical samples and human urine/serum samples.More researches have been done on the action mechanism of BLFX-Tb³⁺-SDBS.The main characteristics of this thesis are as follows:1.The new BLFX-Eu³⁺and BLFX-Tb³⁺fluorescence system are set up and used for determination of BLFX in biological samples and pharmaceutical samples. 2.The sensitivity and selectivity of the fluorescence system is greatly increased by defferent measures.3.The mechanism of fluorescence enhancement effect has been discussed.The research above is of potential value in determination of rare earth ions,drugs and biomoleculars and is of great benefit to interrelated study of rare earth ionfluoroquinolones complex.