Study On The Interaction Between Polybrominated Diphenyl Ethers And Their Derivatives With Biological Molecules

Polybrominated Diphenyl Ethers(PBDEs)has been widely used as brominated flame retardants due to its excellent flame retardation and favourable physical properties.With the gradual increase in concentrations of PBDEs in the environment,PBDEs and their derivatives has produced a variety of influences and hazards on human health and other organisms.Thus,the understanding of the interaction between PBDEs and their derivatives with biological molecules is of great significance to the study of their biotoxicity effect.In this paper,the interaction between PBDEs and their derivatives and three kinds of biological molecules was studied using fluorescence analysis,namely,human serum albumin(HSA),protein disulfide isomerase(PDI)and glutathione(GSH).In the first chapter,we have made a brief overview of PBDEs and their hydroxy,quinone and methoxy derivatives,including the introduction of their origin,toxicity and research status.Meanwhile,the purpose and the main contents of this paper have been put forward.In the second chapter,the interaction of OH-PBDEs and HSA was investigated using 4-OH-2,2',3,4'-tetrabromodiphenyl ether(4-OH-BDE-42)as a representative.The binding constant,the number of binding sites and binding site were investigated using the endogenous fluorescent of HSA.The predominant forces of the interaction were Van der Waals and hydrogen bonds which was made clear in this chapter.We also analyzed the alterations of HSA protein secondary structure in presence of 4-OH-BDE-42.Meanwhile,equilibrium dialysis experiment was performed to study the influence of 4-OH-BDE-42 to the physiological function,mainly the transportation of micromolecules,of HSA.In the third chapter,a fluorescent sensor based on the fluorescent probe for the study of the interaction between OH-PBDEs and PDI,has been developed.The fluorescent probe F-T3 was synthesized by combining 3,3',5-triiodothyronine(T3)and fluorescein isothiocyanate(FITC).The iodine atom in T3 quenched the fluorescent of FITC.While F-T3 interacted with PDI,the iodine atom was wrapped by PDI,leading the recovery of fluorescent.OH-PBDEs have similar chemical structure with T3,and OH-PBDEs can compete with T3 to occupy the T3 binding site on PDI and result in the fluorescent reduction again.It turned out that OH-PBDEs are competitive inhibitor of the binding between T3 and PDI,and OH-PBDEs can bind to PDI in the T3 binding site.In the fourth chapter,a fluorescent sensor based on the DNA-stabilized Ag nanoclusters(DNA-AgNCs)for the study of the interaction between PBDEs quinone derivative(PBDE-Qs)and GSH.Under the protection of cytosine-rich DNA,fluorescent AgNCs were synthesized.Electron transfer can occur between PBDE-Qs and DNA-AgNCs,and lead to the fluorescence quenching.When there exists nucleophile GSH,the Michael addition reaction occurs between GSH and PBDE-Qs and hinders the electron transfer process,thus the fluorescence intensity gradually restored.This sensor can be used to study the interaction degree between GSH and PBDE-Qs via the change of fluorescence intensity,and can be used as a quantitative detection and analysis tools of PBDE-Qs and GSH.In a certain degree,it has environmental and physiological significance.