Interaction Between Drugs And Proteins In The Presen-ce Of Metal Ionsin Ionic Liquidaqueous Two-phase

Ionic liquid aqueous two-phase often consist of both organic cations andinorganic anions that,in contrast to common electrolytes,is liquid at low temperatures orroom temperatures.It possesses many merits compared with traditional polymer andorganic solvent aqueous two-phase,for instance,fast and high-efficiency separating of thephases、 not easily emulsified,clear phase interface,Environment friendly and easy tofacilitate recycling afer simple processing.There-fore,ionic liquid aqueous two-phase hasbeen widely used in the fields of extraction and purification.Here in this work,ionic liquidaqueous two-phase composed by in ionic liquid [Bmim]Br (1-butyl-3-methylimidazoliumbromide) and ammonium sulfate,we studyed interaction between drugs and proteins in thepresence of metal ions in this kind of ionic liquid aqueous two-phase.Fluorescencespectroscopy,UV absorption spectrometry and synchronous fluorescence spectroscopywere used to obtain some basic information of interaction between them,such as quenchingtype,the types of interaction force,the binding constants,the binding pointnumbers,conformation changes and the energy transfer between drugs and BSA.It is ofimportant significance to know the storage,transportation,metabolism and effect of drugs inthe body.This thesis is divided into five chapters:Chapter1:Brief introduction of the funcuions and features of ionic liquid aqueoustwo-phase,the nature and function of BSA,drugs and metal ions,the research methods ofinteraction between BSAand drugs in ionic liquid aqueous two-phase.Chapter2:The interaction between norfloxacin and BSA in the presence of Fe(Ⅲ) wasstudied in ionic liquid aqueous two-phase by using fluorescence spectrum and ultravioletabsorption spectroscopy.The research showed that these interactions resulted in thefluorescence quenching of BSA,which belonged to static quenching mechanism.Bycalculation the binding constants were3.56×106L mol-1(298K)and5.43×105L mol-1(288K),and the binding sites were1.17(288K)and1.08(298K).The thermodynamicparameters showed that the interaction between NFLX and BSA was mainly driven byhydrophobic force.Synchronous spectrum was used to investigate the conformational change of BSA.The shortest binding distance(r=2.00nm)between acceptor(NFLX)anddonor(BSA)were obtained by F rster snonradiative energy trans-fer mechanism.Thepresence of Fe(Ⅲ)resulted in the increase of quenching constants,binding constants andbinding sites between NFLX and BSA,the presence of Fe(Ⅲ)showed synergistic effect onthe interaction between norfloxacin and BSA.Chapter3:The interaction between ciprofloxacin (CPFX) and BSA in the presence ofCu(Ⅱ)was studied by using fluorescence spectrum,the research showed that theseinteractions resulted in the fluorescence quenching of BSA,which belonged to staticquenching mechanism.By calculation the binding constants were4.546×104L mol-1(300KK) and4.740×104L mol-1(310K),and the binding sites were0.9566(300K) and0.9899(310K).The presence of Cu(Ⅱ)resulted in the increase of quenchingconstants,binding constants and binding sites between CPFX and BSA.The thermodynamicparameters showed that the interaction between CPFX and BSA was mainly driven byhydrophobic force.The effect of CPFX on the conformation of BSA was studied by usingsynchronous fluorescence spectroscopy,CPFX showed quenching effect on both Tyrand Trp residues,however,characteristic peak of fluorescence spectra of Trp residue showedobvious red shift,the result indicates the increase of polarity and hydrophobic reduce in themicroenvironment of BSA.The binding distance between CPFX and BSA was calculatedby F rster’s nonradiative energy transfer mechanism.Chapter4:Interaction between LVFX and BSA reacted under the optimum reactionconditions in ionic liquid aqueous two-phase,the experimental results indicated that thefluorescence quenching between LVFX and BSA was a static quenching.The quenchingconstant,binding constant and binding sites of interaction between LVFX and BSAdecresed in the presence of Zn2+.The thermodynamic parameters showed that theinteraction between LVFX and BSA was mainly hydrogen bond or Vander Waalsforces.The effect of LVFX on the conformation of BSA was studied by using synchronousfluorescence spectroscopy.The binding distance between LVFX and BSA was calculatedby F rster’s nonradiative energy transfer mechanism.A new method of measuring LVFXwas established based the fluorescence quenching between LVFX and BSA,and this wasapplied into actual samples.Chapter5:Conclusion and outlook.